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See detailExperimental validation of a thermal model of a LOx flooded ball bearing
Servais, Christophe ULg; Bozet, Jean-Luc ULg; Kreit, Patrick ULg et al

in Tribology International (2014), 80

Ball bearings of turbopumps of rocket engines work in very singular conditions; they are flooded into liquid oxygen or liquid hydrogen. Therefore, the use of any conventional lubricants (oil or grease) is ... [more ▼]

Ball bearings of turbopumps of rocket engines work in very singular conditions; they are flooded into liquid oxygen or liquid hydrogen. Therefore, the use of any conventional lubricants (oil or grease) is prescribed. Although cryogenic fluids can cool this kind of ball bearing, they cannot separate the surfaces in contact. As a result, there is a significant increase in frictional power losses. This paper presents tests performed on a cryotechnic ball bearing flooded in liquid oxygen. The test results showed that beyond a critical loading of the bearing, a sudden increase in temperature occurred. A thermal model is also put forward, in order to understand and anticipate especially the thermal instability described above. [less ▲]

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See detailLe roman pour la jeunesse: un roman éducatif qui ne dit jamais son nom
Delbrassine, Daniel ULg

in Van Beveren, Julien (Ed.) Littérature, langue et didactique. Hommages à Jean-Louis Dumortier (2014)

Démonstration du caractère éducatif du roman pour la jeunesse actuel: à travers des procédés implicites typiques du roman moderne, les auteurs continuent de dispenser un message aux lecteurs.

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See detailExplaining the CMS Higgs lepton-flavor violating
Aristizabal Sierra, Diego ULg; Vicente, Avelino ULg

in Physical Review. D : Particles and Fields (2014), 90(11), 115004

Direct searches for lepton flavor violating Higgs boson decays in the τ μ channel have been recently reported by the CMS collaboration. The results display a slight excess of signal events with a ... [more ▼]

Direct searches for lepton flavor violating Higgs boson decays in the τ μ channel have been recently reported by the CMS collaboration. The results display a slight excess of signal events with a significance of 2.5σ, which translates into a branching ratio of about 1%. By interpreting these findings as a hint for beyond the standard model physics, we show that the Type-III 2HDM is capable of reproducing such signal while at the same time satisfying vacuum stability, perturbativity, electroweak precision data, measured Higgs standard decay modes and low-energy lepton flavor violating constraints. We have found that the allowed signal strength ranges for the bb, WW* and ZZ* standard channels shrink as soon as BR(h→τμ)∼ 1% is enforced. Thus, we point out that if the excess persists, improved measurements of these channels may be used to test our Type-III 2HDM scenario. [less ▲]

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See detailInput of supercritical carbon dioxide to polymer synthesis: an overview
Boyère, Cédric; Jérôme, Christine ULg; Debuigne, Antoine ULg

in European Polymer Journal (2014), 61

The ongoing search for environmentally friendlier alternative to the organic solvents used in chemical processes has led to the development of technologies based on supercritical carbon dioxide (scCO2 ... [more ▼]

The ongoing search for environmentally friendlier alternative to the organic solvents used in chemical processes has led to the development of technologies based on supercritical carbon dioxide (scCO2), which is non-flammable, non-toxic and relatively inert fluid. Polymer chemistry does not escape this trend and last achievements in the field of polymer synthesis in scCO2 are reviewed here. Without claiming to be exhaustive, we go through and discuss the benefits of the main polymerization processes in scCO2 including homogeneous, precipitation, dispersion, suspension and emulsion systems. A particular attention is drawn to water/carbon dioxide emulsion polymerization and to the suited surface active agents. This review also underlines that heterogeneous polymerization based on CO2 is more than a strategy for reducing the ecological footprint of the polymer production but it allows structuring the polymer materials into particles or highly interconnected macroporous networks. [less ▲]

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See detailFatigue et auto-évaluation chez des patients atteints de sclérose en plaques
DELRUE, Gaël ULg; Blavier, Adelaïde ULg; HENNEN, Julie et al

Poster (2014, December)

Different fatigue scales specific for multiple sclerosis patients correlate quite differently with other psychological measures which gives rise to a necessary reflexion about the tools used in clinical ... [more ▼]

Different fatigue scales specific for multiple sclerosis patients correlate quite differently with other psychological measures which gives rise to a necessary reflexion about the tools used in clinical practice and their meanings. [less ▲]

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See detailTransient small-scale structure in the main auroral emission at Jupiter
Palmaerts, Benjamin ULg; Radioti, Aikaterini ULg; Grodent, Denis ULg et al

in Journal of Geophysical Research. Space Physics (2014), 119

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See detailWhat can we learn from asteroseismology of β Cephei stars through forward approach modelling?
Salmon, Sébastien ULg; Montalban, J.; Miglio, A. et al

Poster (2014, December)

The beta Cephei pulsating stars present a unique opportunity to test and probe our knowledge on the interior of massive stars. The information we can obtain depends on the quality and number of ... [more ▼]

The beta Cephei pulsating stars present a unique opportunity to test and probe our knowledge on the interior of massive stars. The information we can obtain depends on the quality and number of observational constraints, both seismic and classical ones. The asteroseismology of beta Cephei stars proceeds by a forward approach, which often result in multiple solutions, without clear indication on the level of confidence. We seek a method to derive confidence intervals on stellar parameters obtained by forward approach and investigate how these latter behave depending the seismic data accessible to the observer. We realise forward modelling with help of a grid of pre-computed models and use Monte-Carlo simulations to build confidence intervals on the inferred stellar parameters. We apply and test this method in a series of hare and hound exercises on a subset of theoretical models simulating observed stars. Results show that a set of 5 frequencies (with knowledge of their associated angular degree) yields good seismic constraints. In particular, presence of mixed modes provides a strong diagnosis on the evolutionary state of the star. Significant errors on the determinination of the extent of the central mixed region appear when the theoretical models do not present the same chemical mixture as the observed star. [less ▲]

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See detailValidation d’un questionnaire d’ergonomie cognitive relatif au travail chez des patients atteints de sclerose en plaques
Blavier, Adelaïde ULg; DELRUE, Gaël ULg; HENNEN, Julie et al

Poster (2014, December)

We present datas validating the use of our QUIPSEP questionnaire among multiple sclerosis patients actually employed.

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See detailUn blog plutôt qu’un Word ? Retour d’expérience de l’insertion d’un cours en ligne dans un programme de formation d’enseignants du supérieur.
Jérôme, Françoise ULg; Verpoorten, Dominique ULg

in Education & Formation (2014), e-302

En 2012-2013, le CAPAES (Certificat d’Aptitude Pédagogique Approprié à l’Enseignement Supérieur) de l’Université de Liège a incorporé pour la première fois à son programme un cours entièrement en ligne ... [more ▼]

En 2012-2013, le CAPAES (Certificat d’Aptitude Pédagogique Approprié à l’Enseignement Supérieur) de l’Université de Liège a incorporé pour la première fois à son programme un cours entièrement en ligne. L’article en expose les motivations sous-jacentes, présente les outils utilisés et analyse la réception du dispositif par les étudiants. Les données récoltées font apparaitre : a) la familiarité antérieure restreinte des enseignants avec les deux outils exploités dans le cours (une plate-forme eLearning traditionnelle et un blog comme représentant du Web 2.0), b) la capacité, en dépit de cette familiarité limitée, de faire bon usage des deux outils en tant qu’apprenant, c) une satisfaction générale pour le cours en ligne mais faiblement liée à la découverte des deux outils et à la prise de conscience, en tant qu’enseignant, de leur potentiel pédagogique. (L'article fournit en annexe le questionnaire complet utilisé pour recueillir le feed-back des enseignants ayant terminé le cours en ligne). [less ▲]

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See detailOn Projection-Based Model Reduction of Biochemical Networks Part I: The Deterministic Case
Sootla, Aivar ULg; Anderson, James

in Proceedings of the 53rd IEEE Conference on Decision and Control (2014, December)

This paper addresses the problem of model reduction for dynamical system models that describe biochemical reaction networks. Inherent in such models are properties such as stability, positivity and ... [more ▼]

This paper addresses the problem of model reduction for dynamical system models that describe biochemical reaction networks. Inherent in such models are properties such as stability, positivity and network structure. Ideally these properties should be preserved by model reduction procedures, although traditional projection based approaches struggle to do this. We propose a projection based model reduction algorithm which uses generalised block diagonal Gramians to preserve structure and positivity. Two algorithms are presented, one provides more accurate reduced order models, the second provides easier to simulate reduced order models. [less ▲]

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See detailOn Projection-Based Model Reduction of Biochemical Networks Part II: The Stochastic Case
Sootla, Aivar ULg; Anderson, James

in Proceedings of the 53rd IEEE Conference on Decision and Control (2014, December)

In this paper, we consider the problem of model order reduction of stochastic biochemical networks. In particular, we reduce the order of (the number of equations in) the Linear Noise Approximation of the ... [more ▼]

In this paper, we consider the problem of model order reduction of stochastic biochemical networks. In particular, we reduce the order of (the number of equations in) the Linear Noise Approximation of the Chemical Master Equation, which is often used to describe biochemical networks. In contrast to other biochemical network reduction methods, the presented one is projection-based. Projection-based methods are powerful tools, but the cost of their use is the loss of physical interpretation of the nodes in the network. In order alleviate this drawback, we employ structured projectors, which means that some nodes in the network will keep their physical interpretation. For many models in engineering, finding structured projectors is not always feasible; however, in the context of biochemical networks it is much more likely as the networks are often (almost) monotonic. To summarise, the method can serve as a trade-off between approximation quality and physical interpretation, which is illustrated on numerical examples. [less ▲]

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See detailLe roman pour la jeunesse
Delbrassine, Daniel ULg

in Ministère de la Culture de la Fédération Wallonie Bruxelles (Ed.) Répertoire des auteurs et illustrateurs de livres pour l'enfance et la jeunesse en Wallonie et à Bruxelles (2014)

Introduction consacrée aux romans pour la jeunesse dans un ouvrage de référence diffusé par le Ministère de la Culture et Wallonie-Bruxelles International

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See detailStigmergy as a mechanism to produce collective vortex behaviours: a study case in shoveler duck
Delcourt, Johann ULg; bode, W. Nikolaï

Poster (2014, December)

Ant mill, caterpillar circle, bat donut, bacteria vortex, duck swirl and fish torus are different names for rotating circular formations of animals, where individuals turn around a common centre. Even if ... [more ▼]

Ant mill, caterpillar circle, bat donut, bacteria vortex, duck swirl and fish torus are different names for rotating circular formations of animals, where individuals turn around a common centre. Even if the ubiquity of this behavioural phenomenon might have suggested common causes or fundamental underlying principles across contexts, a variety of proximate mechanisms can give rise to vortex behaviours. Here, we investigate if stigmergic process (mechanism of self-organisation wit hout direct communication or interaction between individuals) is able to produce different collective behaviours, notably collective vortices. We present an individual-based simulation model for the movement of populations in a resource landscape that allows us to vary the strength of the interactions mentioned above. The key assumption and novelty of our model is that individuals can cause the release of additional nutrients, as well as consuming them. Our model produces clear predictions. For example, we expect more tortuous individual movement paths and higher levels of aggregation in populations occupying homogeneous environments where individual movement makes more nutrients available. We also show how observed movement dynamics could change when local nutrient sources are depleted or when the population density increases. Our predictions are testable and qualitatively reproduce the different feeding behaviours observed in filter-feeding ducks (Anas clypeata), for example. We suggest that considering two-way interactions between feeding individuals and resource landscapes could help to explain fine-scale movement dynamics. [less ▲]

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See detailDeux ans de formation et d’accompagnement techno-pédagogique à l’ULg : public, impact et perspectives
Van de Poël, Jean-François ULg; Verpoorten, Dominique ULg

in Education & Formation (2014), e-302

Cet article présente une recherche quanti-qualitative portant sur 225 enseignants ayant suivi des formations techno-pédagogiques dispensées par la Cellule eCampus (IFRES, Université de Liège, Belgique) de ... [more ▼]

Cet article présente une recherche quanti-qualitative portant sur 225 enseignants ayant suivi des formations techno-pédagogiques dispensées par la Cellule eCampus (IFRES, Université de Liège, Belgique) de 2011 à 2013. Les données récoltées sont utilisées pour : a) qualifier le public de ces formations, b) évaluer, grâce à une grille d’analyse de discours nommée CInOpTIC, leurs effets sur le développement techno-pédagogique des participants, c) étudier la demande d’accompagnement techno-pédagogique, considérée comme un effet induit par les formations. Sur base des données empiriques analysées, l’article élabore des perspectives pour la régulation des formations eLearning. [less ▲]

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See detailGérer les différences : une préoccupation commune
Blondin, Christiane ULg; Cornet, Jacques; Delvaux, Bernard

in Education et formation (2014), e-302

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See detailGenetic structure of nase, Chondrostoma nasus, and common barbel, Barbus barbus (Teleostei, Cyprinidae) populations in South Belgium rivers: toward a rational management of conservation restocking
Gennotte, Vincent ULg; Michaux, Johan ULg; Prignon, Christian ULg et al

Poster (2014, December)

Nase (Chondrostoma nasus) and common barbel (Barbus barbus) are two rheophilic cyprinid fish naturally present in the Belgian Meuse and Rhine basins. During the last decades, the construction of dams ... [more ▼]

Nase (Chondrostoma nasus) and common barbel (Barbus barbus) are two rheophilic cyprinid fish naturally present in the Belgian Meuse and Rhine basins. During the last decades, the construction of dams together with changes in hydrological regimes, modifications of riverbed morphology and water pollution have caused some local dramatic declines in their populations. However, recent improvements in terms of water quality and habitat fragmentation allow considering as realistic a rational restocking plan of locally endangered patrimonial fish species such as nase and common barbel. Restocking operations for a conservation purpose have to be based on the knowledge and the use of wild type genetic strains. Therefore, the aim of this study was to characterize the genetic structure and diversity of nase and common barbel populations in South Belgium rivers. Wild common barbels (n = 313) and nases (n = 271) were sampled by electrofishing in respectively 10 and 6 different tributaries from the Meuse and Rhine rivers. Genotyping was performed on 24 microsatellite markers for each species. Preliminary results showed, for both species, a differential genetic clustering between fish originating from the Meuse basin and those originating from the Rhine basin. Detailed analysis describing the genetic structure and diversity of South Belgium populations will be presented and will serve as a management tool to set up a breeding plan for conservation restocking. [less ▲]

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See detailFungal lipase production by solid-state fermentation
Ramos-Sanchez, L.B.; Julian-Ricardo, M.C.; Cordova, J. et al

Conference (2014, December)

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See detailSustainable Chemistry
Gillet, Sébastien ULg; Jacquet, Nicolas ULg; Richel, Aurore ULg

Learning material (2014)

1) Petrochemical and concept of biorefineries. 2) Biomass and biorefineries, 1st generation 3) Biomass and biorefineries, second generation 4) Green Chemistry and Green Engineering

Detailed reference viewed: 31 (9 ULg)