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See detailThe harmonic balance method for bifurcation analysis of large-scale nonlinear mechanical systems
Detroux, Thibaut ULg; Renson, Ludovic ULg; Masset, Luc ULg et al

in Computer Methods in Applied Mechanics and Engineering (2015), 296

The harmonic balance (HB) method is widely used in the literature for analyzing the periodic solutions of nonlinear mechanical systems. The objective of this paper is to exploit the method for bifurcation ... [more ▼]

The harmonic balance (HB) method is widely used in the literature for analyzing the periodic solutions of nonlinear mechanical systems. The objective of this paper is to exploit the method for bifurcation analysis, i.e., for the detection and tracking of bifurcations of nonlinear systems. To this end, an algorithm that combines the computation of the Floquet exponents with bordering techniques is developed. A new procedure for the tracking of Neimark–Sacker bifurcations that exploits the properties of eigenvalue derivatives is also proposed. The HB method is demonstrated using numerical experiments of a spacecraft structure that possesses a nonlinear vibration isolation device. [less ▲]

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See detailCahiers d'Etudes Germaniques : Lecteurs/spectateurs d'Alexander Kluge
Cormann, Grégory ULg; Hamers, Jérémy ULg; Letawe, Céline ULg

Book published by Université de Provence (2015)

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See detailAvant-propos
Cormann, Grégory ULg; Hamers, Jérémy ULg; Letawe, Céline ULg

in Cahiers d'Etudes Germaniques (2015)

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See detailTentative insight into the multiplicity of the persistent dust maker WR 106 from X-ray observations
De Becker, Michaël ULg

in New Astronomy (2015), 41

This paper presents the results of the analysis of the very first dedicated X-ray observation with XMM-Newton of WR 106. This carbon-rich WC9d Wolf–Rayet star belongs to the category of persistent dust ... [more ▼]

This paper presents the results of the analysis of the very first dedicated X-ray observation with XMM-Newton of WR 106. This carbon-rich WC9d Wolf–Rayet star belongs to the category of persistent dust makers (WCd stars). The issue of the multiplicity of these dust makers is pivotal to understand the dust formation process, and in this context X-ray observations may allow to reveal an X-ray emission attributable to colliding-winds in a binary system. The main result of this analysis is the lack of detection of X-rays coming from WR 106. Upper limits on the X-ray flux are estimated, but the derived numbers are not sufficient to provide compelling constraints on the existence or not of a colliding-wind region. Detailed inspection of archive data bases reveals that persistent dust makers have been poorly investigated by the most sensitive X-ray observatories. Certainly, the combination of several approaches to indirectly constrain their multiplicity should be applied to lift a part of the veil on the nature of these persistent dust makers. [less ▲]

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See detailLe pouvoir des sentiments : Kluge, Adorno, Ferenczi
Hamers, Jérémy ULg; Cormann, Grégory ULg

in Cahiers d'Etudes Germaniques (2015)

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See detailDerivation and Application of Sensitivities to Assess Transient Voltage Sags caused by Rotor Swings
Weckesser, Tilman; Johannsson, Hjortur; Ostergaard, Jacob et al

in International Journal of Electrical Power & Energy Systems (2015), 72

The paper introduces an approach to investigate voltage sags, which are caused by large generator rotor swings following a transient disturbance. Therefore, the method exploits sensitivities derived from ... [more ▼]

The paper introduces an approach to investigate voltage sags, which are caused by large generator rotor swings following a transient disturbance. Therefore, the method exploits sensitivities derived from the algebraic network equations. These provide information on the impact of a generator on the voltage magnitude at a load bus and the e ffect of load variation on the generator's power injection. It is shown that these sensitivities give valuable information to identify critical generator-load pairs and locations for applying preventive control measures. [less ▲]

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See detailA Parallel Processing Approach to Dynamic Simulations of Combined Transmission and Distribution Systems
Aristidou, Petros ULg; Van Cutsem, Thierry ULg

in International Journal of Electrical Power & Energy Systems (2015), 72

Simulating a power system with both transmission and distribution networks modeled in detail is a huge computational challenge. In this paper, a Schur-complement-based domain decomposition algorithm is ... [more ▼]

Simulating a power system with both transmission and distribution networks modeled in detail is a huge computational challenge. In this paper, a Schur-complement-based domain decomposition algorithm is proposed to provide accurate, detailed dynamic simulations of such systems. The simulation procedure is accelerated with the use of parallel programming techniques, taking advantage of the parallelization opportunities inherent to domain decomposition algorithms. The proposed algorithm is general, portable and scalable on inexpensive, shared-memory, multi-core machines. A large-scale test system is used for its performance evaluation. [less ▲]

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See detailL'énonciation énoncée dans l'image
Dondero, Maria Giulia ULg

in Colas-Blaise, Marion; Tore, Gian Maria; Perrin, Laurent (Eds.) Le sens de l’énonciation (2015)

Le propos de cet article est de rendre compte des développements de la théorie de l’énonciation à la suite de la proposition d’Emile Benveniste d’étendre ce concept à la musique et à d’autres langages non ... [more ▼]

Le propos de cet article est de rendre compte des développements de la théorie de l’énonciation à la suite de la proposition d’Emile Benveniste d’étendre ce concept à la musique et à d’autres langages non verbaux. Un retour sur cette question se révèle aujourd’hui nécessaire pour plusieurs raisons. Certaines sont internes à la discipline et aux sciences du langage — la légitimité du visuel en tant que langage —, d’autres sont extra-disciplinaires, venant surtout des sciences de la communication et de la philosophie de l’art. Nous aborderons ici deux questions fondamentales concernant l’énonciation dans le visuel, étroitement liées entre elles. La première concerne la subjectivité inscrite dans l’image et sera approchée via la notion d’énonciation énoncée (personne/espace/temps). L’analyse énonciative de l’énoncé visuel vise en effet à décrire « d’où l’on voit », à savoir les points de vue à partir desquels l’image a été conçue et demande à être saisie par le regard de l’observateur. La deuxième question concerne la notion de métalangage. Comme l’a affirmé Jacques Fontanille, l’énonciation est « un métalangage "descriptif" car, en prédiquant l’énoncé, elle affiche sa propre activité, elle la code et en fait un événement sensible ou observable » (Sémiotique du discours, 2003, p. 283). Une première interrogation émerge alors : peut-on parler de métalangage dans le cadre du visuel, où il est d’ailleurs déjà difficile de repérer une véritable langue visuelle, dotée d’un alphabet de signes disjoints et d’une grammaire figée ? [less ▲]

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See detailCorps, psychiatrie et philosophie
Englebert, Jérôme ULg

Scientific conference (2015, October 31)

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See detailFlexible multibody system modelling: A geometric local frame approach on SE(3)
Sonneville, Valentin ULg

Scientific conference (2015, October 30)

In order to improve computational costs in the frame of flexible multibody system modelling, we propose a geometrically exact framework relying on a local frame description. Thanks to this framework ... [more ▼]

In order to improve computational costs in the frame of flexible multibody system modelling, we propose a geometrically exact framework relying on a local frame description. Thanks to this framework, geometric non-linearities are strongly reduced for two reasons. Firstly, the equations of motion can be solved without introducing a global parametrization of the motion, which also leads to a naturally singularity-free description of large rotations. Secondly, the equations of motion are expressed in a local frame, both at position and rotation level, leading to intrinsic equations. Accordingly, these equations are insensitive to large amplitude motions, such that the geometric non-linearities are naturally filtered. The mathematical developments are carried out in a Lie group setting which, albeit more abstract than classical treatments, provides generic and powerful well established tools. So far, several elements have been formulated in this framework: rigid body, kinematic joints and a flexible beam finite element. A shell finite element and a super-element are also under development. Some interesting numerical advantages are observed following the reduction of geometric non-linearities, e.g., the iteration matrix depends on relative motion within the elements only and is thus invariant under rigid body motions. [less ▲]

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See detailL'être-au-monde borderline
Englebert, Jérôme ULg

Scientific conference (2015, October 30)

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See detailBenedetto Varchi, gli artisti e l'accademia a Firenze
Geremicca, Antonio ULg

Scientific conference (2015, October 29)

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See detailInternational Classification of Primary Care in a cross-lingual terminology portal (Poster)
Jamoulle, Marc ULg; Kuehlein, Thomas; Pizzanelli, Miguel et al

Poster (2015, October 23)

ICPC, reflecting the burden of family medicine, is available in the HeTOP cross-lingual terminology portal (URL: www.hetop.eu) in 19 languages, mostly European (e.g. Spanish, Portuguese) but also in ... [more ▼]

ICPC, reflecting the burden of family medicine, is available in the HeTOP cross-lingual terminology portal (URL: www.hetop.eu) in 19 languages, mostly European (e.g. Spanish, Portuguese) but also in Japanese or Mandarin. The HeTOP interface has been also translated in 10 languages by Wonca colleagues (including in Turkish, Vietnamese and Romanian). [less ▲]

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See detailEfficiency of shaft sealing for CO2 sequestration in coal mines
Bertrand, François ULg; Charlier, Robert ULg; Collin, Frédéric ULg et al

in International Workshop on Geomechanics and Energy: The Ground as Energy Source and Storage (2015, October 13)

This work examined the efficiency of a shaft sealing system for the CO2 sequestration in abandoned coal mines. The particular case of the coal mine of Anderlues was considered. The performed simulation ... [more ▼]

This work examined the efficiency of a shaft sealing system for the CO2 sequestration in abandoned coal mines. The particular case of the coal mine of Anderlues was considered. The performed simulation took into account the anisotropic behaviour of shale and the presence of coalbeds. [less ▲]

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See detailLes visages d'Alain Baczynsky
Englebert, Jérôme ULg; Séguin, Marion

Scientific conference (2015, October 10)

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See detailUnderstanding how people with MS get tired while walking
Pierard, Sébastien ULg; Phan-Ba, Rémy; Van Droogenbroeck, Marc ULg

in Multiple Sclerosis Journal (2015, October 09)

BACKGROUND. Walking impairment is frequent, appears early in the disease course of MS patients (MSP), and is perceived as the most disabling symptom. When walking, patients get tired more and differently ... [more ▼]

BACKGROUND. Walking impairment is frequent, appears early in the disease course of MS patients (MSP), and is perceived as the most disabling symptom. When walking, patients get tired more and differently than healthy people (HP) [Phan-Ba et al PLOS 2012]. This limits their walking perimeter. Understanding this phenomenon is thus important to suggest adequate therapies at the right time. OBJECTIVE. Our aim is to understand how MSP get tired while walking compared to HP. Two groups of MSP are considered: those with a low disability level (MSPL) and those with a high one (MSPH). We consider two criteria to measure the disability: the EDSS and the deceleration index (DI) [Phan-Ba et al PLOS 2012]. The limit between the groups is set at DI=0.8 and EDSS=3 (inclusive for MSPL). METHODS. Many gait characteristics (GC) have been measured with the system GAIMS along a 500m path walked as fast as possible. The dataset gathers 464 visits of HP and 70 of MSP. Some people have been assessed several times. There are 33 visits in the group MSPL with the EDSS criterion, and 25 with the DI criterion. Statistical tests (Welch) were performed on the differences and relative differences of the GC measured during the first and last 100m of the test to detect differences between HP and MSPL, and between MSPL and MSPH, as in [ECTRIMS 2012 P755]. RESULTS. Both criteria for defining the groups lead to similar conclusions. For many GC, the distributions of the variations are significantly different between MSPL and MSPH. The largest difference is for the relative difference of speed (p=0.000119 for EDSS and p=0.000021 for DI). In contrast, only the variation of the average lateral distance between the feet, which is related to the size of the base of support (and thus to the balance) shows a very significant difference between HP and MSPL (p=0.000116 for EDSS and p=0.000120 for DI). The balance does not seem to change much from MSPL to MSPH. Besides, we note that the variance decreases slightly from HP to MSPL and increases a lot from MSPL to MSPH. CONCLUSIONS. Statistically, from the motor fatigue point of view, it seems that the course of the MS disease is divided in two different stages. In the first one, MSP get more tired than HP because of a deterioration of the balance. Then, in the second one, their fatigue becomes related to a faster decrease of the walking speed. This suggests that physical therapy exercises focused on the balance could be given to MSP in the early stage of the disease. [less ▲]

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