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See detailComparison of experimental results and numerical modelling of unreinforced load-bearing masonry structures subjected to earthquake loading
Mordant, Christophe ULg; Denoël, Vincent ULg; Degée, Hervé

in Proceedings of the SECED 2015 Conference: Earthquake Risk and Engineering towards a Resilient World (2015, July)

This paper presents a comparison of experimental tests results on unreinforced load-bearing masonry structures subjected to earthquake loading with numerical predictions. First, simple walls are submitted ... [more ▼]

This paper presents a comparison of experimental tests results on unreinforced load-bearing masonry structures subjected to earthquake loading with numerical predictions. First, simple walls are submitted to cyclic and shaking table tests. Some of them include soundproofing devices in order to investigate their influence on the general behaviour in static and dynamic conditions. Additional walls with an opening and T-shaped walls are then tested under cyclic loading. The study is focused on the frame effect, the contribution of the perpendicular wall to the global strength and the efficiency of the connection. These aspects are also studied through shaking table tests on two masonry frames with T- or L-shaped piers. The main information is expressed in terms of force-displacement curves, mechanical properties and energy dissipation for the cyclic tests. The shaking table tests provide results in terms of dynamic and mechanical properties. Comparison of the results with numerical predictions is finally performed thanks to the software TREMURI. [less ▲]

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See detailIntergenerational physical activity: Effects of a three-month intervention bringing together older adults and elementary school children
Mouton, Alexandre ULg; Renier, Tom ULg; Cloes, Marc ULg

in Revista Espaňola de Educación Física y Deportes (2015, July), 410-S

For the first time in history, children are projected to have a shorter life expectancy than their parents (Olshansky et al., 2005). Besides, older adults are the less active population group (Sun et al ... [more ▼]

For the first time in history, children are projected to have a shorter life expectancy than their parents (Olshansky et al., 2005). Besides, older adults are the less active population group (Sun et al., 2013). Intergenerational PA has the potential to increase PA and quality of life (QoL) among those two age-groups but research in the field is still very limited (Flora & Faulkner, 2007). Accordingly, the aim of this study was to examine the impact of an intergeneration PA intervention on self-reported PA and Qol among older adults and elementary school children. At baseline, two intergenerational groups were formed: (Gr1) 11 older adults (63.91±7.62 years) and a class of 18 children (4.81±0.37 years); (Gr2) 9 older adults (68.67±7.25) and a class of 13 children (7.16±0.38years). Those groups took part in a three-month intergenerational intervention including one weekly session of PA practiced in the school context. Assessments were performed before (T0), during (satisfaction level), after the intervention (T1) and after a three months’ follow-up period (T2). PA and Qol were respectively assessed with the QAPPA and the SF-36 among older adults, and with adapted versions of the PAQ-C and the AUQUEI among children. Older adults’ physical fitness was also assessed with the SFT battery test. Participation rate was relatively high in both groups during PA sessions (Gr1: 81.48% older adults and 93.21% children; Gr2: 83.33% older adults and 91.45% children). At T1, Only 1 older adult (Gr1) dropped out of the study, as 9 children (group 1) and 6 children (group 2) dropped out due to the failure of the parents to complete and return the children’s questionnaires. Preliminary results of the SFT exposed significant improvements of the upper limbs strength in both groups (p<0.05). Further analyses will inform about effects on PA and Qol. [less ▲]

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See detailSemi-empirical correlation to model heat losses along solar parabolic trough collectors
Dickes, Rémi ULg; Lemort, Vincent ULg; Quoilin, Sylvain ULg

Conference (2015, July)

Solar thermal power plants convert sunshine energy into useful heat and electricity by means of solar collectors and a thermodynamic cycle. Among the different solar collector technologies, parabolic ... [more ▼]

Solar thermal power plants convert sunshine energy into useful heat and electricity by means of solar collectors and a thermodynamic cycle. Among the different solar collector technologies, parabolic troughs are nowadays the most widespread together with solar towers. In order to improve the computation speed required to simulate the temperature profile along solar parabolic trough collectors, a correlation estimating the effective heat losses of the receiver is an essential tool. However, the relations found in the literature lack accuracy and do not translate effectively the effects of the operating conditions in all cases. In this work, an alternative correlation is proposed and calibrated with the results of a deterministic model. Better fitting performance is demonstrated when compared to the prediction of the pre-existing correlations. The benefits and limitations of the new correlation are finally assessed. [less ▲]

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See detailModel reduction for simulating the dynamic behavior of parabolic troughs and a thermocline energy storage in a micro-solar power unit
Dickes, Rémi ULg; Desideri, Adriano ULg; Lemort, Vincent ULg et al

Conference (2015, July)

Micro-scale concentrated solar power plants are characterized by strong transients and mostly operate in off-design working conditions. Both the sizing and the control of these systems are key challenges ... [more ▼]

Micro-scale concentrated solar power plants are characterized by strong transients and mostly operate in off-design working conditions. Both the sizing and the control of these systems are key challenges whose optimization requires powerful dynamic modeling tools. In this context, a system featuring a solar field of parabolic troughs, a thermocline thermal energy storage and a 5kWe organic Rankine cycle (ORC) power unit is modeled in the Modelica language. Model reduction methods applied to the solar field and the thermal storage are investigated and analyzed to improve the computational efficiency of the problem. Each model is described and integrated in the open-source ThermoCycle library. Results of simulation under identical operating conditions are compared and the benefits and limitations of model reduction are assessed. [less ▲]

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See detailAn XFEM/CZM implementation for massively parallel simulations of composites fracture
Vigueras, Guillermo; Sket, Federico; Samaniego, Cristobal et al

in Composite Structures (2015), 125

Because of their widely spread use in many industries, composites are the subject of many research campaigns. More particularly, the development of both accurate and flexible numerical models able to ... [more ▼]

Because of their widely spread use in many industries, composites are the subject of many research campaigns. More particularly, the development of both accurate and flexible numerical models able to capture their intrinsically multiscale modes of failure is still a challenge. The standard finite element method typically requires intensive remeshing to adequately capture the geometry of the cracks and high accuracy is thus often sacrificed in favor of scalability, and vice versa. In an effort to preserve both properties, we present here an extended finite element method (XFEM) for large scale composite fracture simulations. In this formulation, the standard FEM formulation is partially enriched by use of shifted Heaviside functions with special attention paid to the scalability of the scheme. This enrichment technique offers several benefits, since the interpolation property of the standard shape function still holds at the nodes. Those benefits include (i) no extra boundary condition for the enrichment degree of freedom, and (ii) no need for transition/blending regions; both of which contribute to maintain the scalability of the code. Two different cohesive zone models (CZM) are then adopted to capture the physics of the crack propagation mechanisms. At the intralaminar level, an extrinsic CZM embedded in the XFEM formulation is used. At the interlaminar level, an intrinsic CZM is adopted for predicting the failure. The overall framework is implemented in ALYA, a mechanics code specifically developed for large scale, massively parallel simulations of coupled multi-physics problems. The implementation of both intrinsic and extrinsic CZM models within the code is such that it conserves the extremely efficient scalability of ALYA while providing accurate physical simulations of computationally expensive phenomena. The strong scalability provided by the proposed implementation is demonstrated. The model is ultimately validated against a full experimental campaign of loading tests and X-ray tomography analyses for a chosen very large scale. [less ▲]

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See detailBilevel optimization in the context of intermodal pricing: state of art
Tawfik, Christine Maher Fouad ULg; Limbourg, Sabine ULg

Scientific conference (2015, July)

With the rising interest to stimulate intermodal transport, determining pricing strategies can be intrinsically challenging. We provide a review on the current state of research in intermodal pricing ... [more ▼]

With the rising interest to stimulate intermodal transport, determining pricing strategies can be intrinsically challenging. We provide a review on the current state of research in intermodal pricing, through which we identify a peculiar gap in optimization approaches. A suggestion to exploit the bilevel optimization technique is presented, as well as an account of its widely successful application to price setting problems. The different approaches to express the network users’ behavior, regarded as the lower level problem, are highlighted together with the particular modeling aspects of intermodal networks. [less ▲]

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See detailLe syndrome tarsien antérieur
MILANTS, Christophe ULg; WANG, François-Charles ULg; Gomulinski, Léon et al

in Revue Médicale de Liège (2015), 70(7-8), 400-404

The anterior tarsal tunnel syndrome is a rare entrapment neuropathy of the deep peroneal nerve beneath the inferior extensor retinaculum of the ankle. It is unrecognized and may lead to misdiagnosis and ... [more ▼]

The anterior tarsal tunnel syndrome is a rare entrapment neuropathy of the deep peroneal nerve beneath the inferior extensor retinaculum of the ankle. It is unrecognized and may lead to misdiagnosis and delayed treatment. We report the case of a 77 years old patient complaining of anterior tarsal tunnel syndrome’s symptoms with neuropathic pain located at the dorsal part of the foot without any sensorimotor loss. The electroneuromyography was in favour of the motor impairment of the deep peroneal nerve. MRI exploration of the ankle showed a millimetric bony overgrowth of the upper pole of the navicular irritative to the deep peroneal nerve. Infiltration at overgrowth of the navicular provided a partial and temporary decrease in pain symptoms. Surgical nerve decompression was then considered. [less ▲]

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See detailLANDSLIDES IN CENTRAL AFRICA: FROM DEFORMATION MECHANISMS TO EVOLUTION PROCESSES – CASES STUDIES FROM RWANDA AND BURUNDI
Draidia, Salah ULg; Ndahimana, Hamuli; Habimana, Christophe et al

Scientific conference (2015, July)

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See detailHow bioméchanical analysis may help to identify abdominal injury causes in high level tennis
Tubez, François ULg; Forthomme, Bénédicte ULg; Croisier, Jean-Louis ULg et al

Conference (2015, July)

This research studies the case of a professional tennis player who has suffered from a medical tear on the left rectus abdominis muscle after a tennis serve. The goal of the study is to understand whether ... [more ▼]

This research studies the case of a professional tennis player who has suffered from a medical tear on the left rectus abdominis muscle after a tennis serve. The goal of the study is to understand whether the injury could be explained by an inappropriate technique. For this purpose, we analyzed the three dimensions kinematic and kinetic of the serve. We also performed isokinetic tests of the knees. We compared the player to five other professional players. We observed a possible deficit of energy transfer because of an important anterior pelvis tilt. Some compensations of the player during serve could be a possible higher abdominal contraction and a larger shoulder external rotation. These particularities could induce an abdominal overwork that would explain the first injury and may provoke a new injury. [less ▲]

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See detailImpacts of climate change on future flood damage on the river Meuse, with a distributed uncertainty analysis
Detrembleur, Sylvain; Stilmant, Frédéric ULg; Dewals, Benjamin ULg et al

in Natural Hazards (2015), 77(3), 1533-1549

Flood-risk assessments are an objective and quantitative basis for implementing harmonized flood mitigation policies at the basin scale. However, the generated results are subject to different sources of ... [more ▼]

Flood-risk assessments are an objective and quantitative basis for implementing harmonized flood mitigation policies at the basin scale. However, the generated results are subject to different sources of uncertainty arising from underlying assumptions, data availability and the random nature of the phenomenon. These sources of uncertainty are likely to bias conclusions because they are irregularly distributed in space. Therefore, this paper addresses the question of the influence of local features on the expected annual damage in different municipalities. Based on results generated in the frame of a transnational flood-risk-assessment project for the river Meuse (Western Europe) taking climate change into account, the paper presents an analysis of the relative contributions of different sources of uncertainty within one single administrative region (the Walloon region in Belgium, i.e. a river reach of approximately 150 km). The main sources of uncertainty are not only found to vary both from one municipality to the other and in time, but also to induce opposite effects on the computed damage. Nevertheless, practical conclusions for policy-makers can still be drawn. [less ▲]

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See detailDynamique et structure de la haute atmosphère de Mars
Stiepen, Arnaud ULg

Book published by Edition Européenne Universitaire (2015)

La haute atmosphère de Mars est une région clé pour notre compréhension de son évolution. Par analogie, l'étude de Mars permettra de mieux cerner les grands changements climatiques terrestres. Depuis 2003 ... [more ▼]

La haute atmosphère de Mars est une région clé pour notre compréhension de son évolution. Par analogie, l'étude de Mars permettra de mieux cerner les grands changements climatiques terrestres. Depuis 2003, la sonde Mars Express de l'ESA observe la thermosphère de Mars par le biais des traceurs de sa composition, structure et dynamique que sont les luminescences atmosphériques. Cette étude se concentre sur l'observation ultraviolette de la haute atmosphère de Mars et propose des résultats inédits concernant ses propriétés. Cet ouvrage lance aussi des pistes pour de futures observations grâce à la sonde MAVEN de la NASA. [less ▲]

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See detailThe Geoarchaeology of Utica, Tunisia: The Paleogeography of the Mejerda Delta and Hypotheses Concerning the Location of the Ancient Harbor
Delile, Hugo; Abichou; Gadhoum, Ahmed et al

in Geoarchaeology (2015), 30(4), 291-306

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See detailLong-term XMM-Newton investigation of two particle-accelerating colliding-wind binaries in NGC6604: HD168112 and HD167971
De Becker, Michaël ULg

in Monthly Notices of the Royal Astronomical Society (2015), 451(1), 5589-5599

The long-term (over more than one decade) X-ray emission from two massive stellar systems known to be particle accelerators is investigated using XMM-Newton. Their X-ray properties are interpreted taking ... [more ▼]

The long-term (over more than one decade) X-ray emission from two massive stellar systems known to be particle accelerators is investigated using XMM-Newton. Their X-ray properties are interpreted taking into account recent information about their multiplicity and orbital parameters. The two targets, HD168112 and HD167971 appear to be overluminous in X-rays, lending additional support to the idea that a significant contribution of the X-ray emission comes from colliding-wind regions. The variability of the X-ray flux from HD168112 is interpreted in terms of varying separation expected to follow the 1/D rule for adiabatic shocked winds. For HD167971, marginal decrease of the X-ray flux in September 2002 could tentatively be explained by a partial wind eclipse in the close pair. No long-term variability could be demonstrated despite the significant difference of separation between 2002 and 2014. This suggests the colliding-wind region in the wide orbit does not contribute a lot to the total X-ray emission, with a main contribution coming from the radiative shocked winds in the eclipsing pair. The later result provides evidence that shocks in a colliding-wind region may be efficient particle accelerators even in the absence of bright X-ray emission, suggesting particle acceleration may operate in a wide range of conditions. Finally, in hierarchical triple O-type systems, thermal X-rays do not necessarily constitute an efficient tracer to detect the wind-wind interaction in the long period orbit. [less ▲]

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See detailMedieval Francophone Literary Culture Outside France database
Morato, Nicola ULg; Gaunt, Simon; Gilbert, Jane et al

Textual, factual or bibliographical database (2015)

The database is the major output of the project Medieval Francophone Literary Culture Outside France (an Art and Humanities Research Council project). It contains descriptions of more than 90% of the ... [more ▼]

The database is the major output of the project Medieval Francophone Literary Culture Outside France (an Art and Humanities Research Council project). It contains descriptions of more than 90% of the manuscript witnesses of Prose Lancelot, Prose Tristan, Guiron le Courtois, Roman de Troie, Roman de Alexandre, Histoire Ancienne jusqu'à César. [less ▲]

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See detailSelective top-down control of epiphytic biomass by amphipods from Posidonia oceanica meadows: implications for ecosystem functioning
Michel, Loïc ULg; Dauby, Patrick ULg; Dupont, Alessandra et al

in Belgian Journal of Zoology (2015), 145(2), 83-93

Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipod crustaceans that graze on epiphytes. However, their actual significance for ecosystem functional ... [more ▼]

Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipod crustaceans that graze on epiphytes. However, their actual significance for ecosystem functional processes is hard to estimate, due to the lack of adequate data. Here, a field microcosm-based inclusion experiment was used to test if three of the dominant taxa of the amphipod community (Apherusa chiereghinii, Dexamine spiniventris and Gammarus spp.) could exert top-down control on seagrass leaf epiphytes. Influence of amphipod activity on nutrient availability for the host species was also investigated. All grazer taxa significantly reduced biomasses of erect macroalgae and erect sessile animals present on leaves. None of them consumed encrusting epiflora or epifauna. This selective top-down control could have important implications for the structure of the epiphytic community of P. oceanica leaves, which is one of the most diverse and abundant of all seagrass species. Grazing activity of all taxa caused higher N content of seagrass leaves, likely through amphipod excretion and/or sloppy feeding. Since P. oceanica meadows often grow in oligotrophic zones where plant growth can be nutrient-limited, this N enrichment could enhance seagrass production. Overall, the ecological interaction between P. oceanica and amphipods could be seen as a facultative mutualistic relationship. Our results suggest that amphipod mesograzers are key-elements in some of the functional processes regulating these complex and yet endangered ecosystems, which are essential components of Mediterranean coastal zones. [less ▲]

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See detailThe French language runs throughout the world
Morato, Nicola ULg; Gaunt, Simon

E-print/Working paper (2015)

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See detailL'éveil de la matrix-gla-protéine sonnera le glas des calcifications vasculaires
DELANAYE, Pierre ULg; Liabeuf, Sophie; BOUQUEGNEAU, Antoine ULg et al

in Néphrologie & Thérapeutique (2015), 11(4), 191-200

La matrix-gla-protéine (MGP) est principalement sécrétée par les chondrocytes et les cellules musculaires lisses des parois vasculaires. Son rôle est d’inhiber localement le développement des ... [more ▼]

La matrix-gla-protéine (MGP) est principalement sécrétée par les chondrocytes et les cellules musculaires lisses des parois vasculaires. Son rôle est d’inhiber localement le développement des calcifications vasculaires. MGP doit bénéficier de deux processus post-transcriptionnels avant d’être pleinement active : une phosphorylation de résidus sérine et une carboxylation de résidus glutamate. Cette carboxylation ne peut se faire qu’en présence de quantité suffisante de vitamine K. Plusieurs formes de MGP circulent donc dans le plasma, certaines étant totalement inactives (la MGP déphosphorylée et décarboxylée), d’autres possédant une activité biologique variable en fonction du nombre de sites carboxylés ou phosphorylés. Il existe un lien théorique étroit entre MGP, vitamine K, calcifications vasculaires et maladies cardiovasculaires et ce, particulièrement chez les patients souffrant d’insuffisance rénale chronique, a fortiori s’ils sont dialysés. Si l’existence de ce lien a été démontrée via de nombreuses et solides données fondamentales, les données cliniques restent, à ce jour, observationnelles et doivent donc être interprétées avec prudence. Mesurer une fraction de MGP dans le plasma pour estimer le degré de calcification d’un patient donné n’est pas encore d’actualité . La forme inactive pourrait être utile pour juger des réserves en vitamine K au niveau vasculaire. Dans cet article de revue, nous reviendrons sur les bases théoriques du rôle de MGP dans le processus de calcification vasculaire, sur le défi analytique que représente sa détermination dans le plasma, ainsi que sur les liens entre MGP, vitamine K et calcifications vasculaires en population géne´ rale et chez les patients insuffisants rénaux. [less ▲]

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See detailSpectroscopic survey of Kepler stars. I. HERMES/Mercator observations of A- and F-type stars
Niemczura, E.; Murphy, S. J.; Smalley, B. et al

in Monthly Notices of the Royal Astronomical Society (2015), 450

The Kepler space mission provided near-continuous and high-precision photometry of about 207,000 stars, which can be used for asteroseismology. However, for successful seismic modelling it is equally ... [more ▼]

The Kepler space mission provided near-continuous and high-precision photometry of about 207,000 stars, which can be used for asteroseismology. However, for successful seismic modelling it is equally important to have accurate stellar physical parameters. Therefore, supplementary ground-based data are needed. We report the results of the analysis of high-resolution spectroscopic data of A- and F-type stars from the Kepler field, which were obtained with the HERMES spectrograph on the Mercator telescope. We determined spectral types, atmospheric parameters and chemical abundances for a sample of 117 stars. Hydrogen Balmer, Fe I, and Fe II lines were used to derive effective temperatures, surface gravities, and microturbulent velocities. We determined chemical abundances and projected rotational velocities using a spectrum synthesis technique. The atmospheric parameters obtained were compared with those from the Kepler Input Catalogue (KIC), confirming that the KIC effective temperatures are underestimated for A stars. Effective temperatures calculated by spectral energy distribution fitting are in good agreement with those determined from the spectral line analysis. The analysed sample comprises stars with approximately solar chemical abundances, as well as chemically peculiar stars of the Am, Ap, and Lambda Boo types. The distribution of the projected rotational velocity, Vsini, is typical for A and F stars and ranges from 8 to about 280 km/s, with a mean of 134 km/s. [less ▲]

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