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See detailUpdate on investigation in IPF - Clinical presentation and epidemiology in domestic animals
Clercx, Cécile ULg

in Proceedings of the Fibrosis Across Species Consortium - Louisville - EU - 27th – 29th April 2014 (2014, July)

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See detailEvent-driven integration of linear structural dynamics models under unilateral elastic constraints
Depouhon, Alexandre ULg; Detournay, Emmanuel; Denoël, Vincent ULg

in Computer Methods in Applied Mechanics & Engineering (2014), 276

This paper proposes an algorithm for the numerical simulation of linear structural dynamics problems under unilateral elastic constraints, i.e., constraints with a linear force/displacement characteristic ... [more ▼]

This paper proposes an algorithm for the numerical simulation of linear structural dynamics problems under unilateral elastic constraints, i.e., constraints with a linear force/displacement characteristic whenever active. The presented procedure relies on an event-driven strategy for the handling of the contact constraints, in combination with one-step schemes dedicated to the time integration of the second-order equations of motion. Efficiency of the procedure follows from the use of cubic Hermite interpolation to continuously extend the normal gap functions that reflect the openings of the contact interfaces. Robustness follows from the proper handling of complex numerical situations, e.g., numerical grazing or discontinuity sticking, through appropriate algorithm structure and numerical implementation. And, integration stability is guaranteed by the very nature of the algorithm and that of the one-step integration scheme. Following a detailed coverage of the integration procedure and the countermeasures to the expected numerical difficulties, three application examples are treated for illustration purposes. A MATLAB implementation of the procedure is provided online; download and usage information are given in the Appendix. [less ▲]

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See detailExcavation damaged zone modelling including hydraulic permeability evolution in unsaturated argilaceous rock
Pardoen, Benoît ULg; Levasseur, Séverine ULg; Collin, Frédéric ULg

in 6th International Conference on Unsaturated Soils (2014, July)

The drilling of galleries induces damage propagation in the surrounding medium and creates the Excavation Damaged Zone (EDZ) in which the material properties are modified. The prediction of the fracture ... [more ▼]

The drilling of galleries induces damage propagation in the surrounding medium and creates the Excavation Damaged Zone (EDZ) in which the material properties are modified. The prediction of the fracture structure and flow properties evolution within this zone are major issues especially in the context of underground nuclear waste storage. Since experimental results indicate that shear strain localisation appears prior to fractures, we model the EDZ with strain localisation in shear band mode using the coupled local second gradient model. The evolution of the intrinsic hydraulic permeability inside the fractures is taken into consideration as well as the influence of gallery ventilation on the rock desaturation. The numerical results provide information about the damaged zone extension, structure and behaviour with good correspondence to in situ measurements and observations. [less ▲]

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See detailSoil compaction resulting from different soil tillage systems
Destain, Marie-France ULg; Roisin, Christian; Mercatoris, Benoît ULg

in ASABE - CSBE/ASABE Joint Meeting Presentation (2014, July)

The effects of long-term use (8 years) of two different tillage systems were assessed on a Luvisol, under temperate climate (Belgium). The tillage treatments were (i) conventional tillage (CT) with ... [more ▼]

The effects of long-term use (8 years) of two different tillage systems were assessed on a Luvisol, under temperate climate (Belgium). The tillage treatments were (i) conventional tillage (CT) with moldboard ploughing to 27 cm depth and (ii) reduced tillage (RT) with a spring tine cultivator to 10 cm depth. The measurements included bulk density (BD) and precompression stress (Pc) chosen as indicators of mechanical strength, and the pore size distribution (PSD) measured by mercury intrusion porosimetry (MIP). The tillage systems, the depth and their interaction had a significant effect on BD, Pc and PSD. In CT, in the topsoil, the soil strength was low and the total porosity n was about 50 %. In the subsoil, n decreased to 43 %. The PSD of CT was uni-modal in topsoil and subsoil in the MIP measurement range. The mean value of the mode rmax diminished from the topsoil toward the subsoil (from 2.5 microns to 1.9 microns). In RT, in the topsoil, the soil strength was higher than CT. BD did not vary much according to the depth. The total porosity n of RT was comprised between 40-45 % in the soil profile. The PSD was uni-modal and rmax increased from topsoil (around 2 microns) to subsoil (> 3 microns). This suggested the agglomeration of fine particles under the long-term action of mechanical loads, climatic agents, biological organisms or clay minerals acting as cementing agents. These phenomena could be at the origin of the increase of Pc with the depth without significant modification of BD. Such high values of Pc could be responsible of negative effects on root-growth leading to a more superficial root lateral development. [less ▲]

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See detailComputation of damped nonlinear normal modes with internal resonances: a boundary value approach
Renson, Ludovic ULg; Touzé, Cyril; Kerschen, Gaëtan ULg

in Proceedings of the 8th European Nonlinear Dynamics Conference (ENOC 2014) (2014, July)

This paper considers the computation of nonlinear normal modes (NNMs) defined as two-dimensional manifolds in phase space. Because existing methods use explicit manifold parameterization, NNM computation ... [more ▼]

This paper considers the computation of nonlinear normal modes (NNMs) defined as two-dimensional manifolds in phase space. Because existing methods use explicit manifold parameterization, NNM computation in the presence of internal resonances requires multiple pairs of constraint coordinates. This paper investigates an alternative method for which the manifold is computed using successive boundary value problems. [less ▲]

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See detailOrthanc - Logiciel libre pour l'imagerie médicale en milieu hospitalier
JODOGNE, Sébastien ULg; LENAERTS, Eric ULg; COUCKE, Philippe ULg et al

in Communications de la Conférence Francophone en Gestion et Ingénierie des Systèmes Hospitaliers (GISEH 2014) (2014, July)

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See detailMovements of endemic and exotic fish in a large river ecosystem (Rhône, France)
Capra, Hervé; Pella, Hervé; Ovidio, Michaël ULg

in Proceedings of the 10th International Conference on Ecohydraulics (2014, July)

The aim of this study is to characterise the mobility templates of two patrimonial species of rheophilic cyprinids (Barbus barbus and Squalius cephalus) and of a species of exotic fish, the catfish ... [more ▼]

The aim of this study is to characterise the mobility templates of two patrimonial species of rheophilic cyprinids (Barbus barbus and Squalius cephalus) and of a species of exotic fish, the catfish (Silurus glanis), in an area of the upper Rhône River characterised by significant disruptions of flow and thermal regimes (caused by hydroelectric and nuclear power plants). Results reveal contrasted mobility patterns, habitat uses and home-range sizes between endemic and exogenous fish species, but with a high interindividual variability. [less ▲]

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See detailQuel système d'évaluations génétiques pour les verrats Piétrain en Wallonie
Dufrasne, Marie ULg; Piedboeuf, Maureen; Wavreille, José et al

Article for general public (2014)

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See detailValidation of a new automatic drowsiness quantification system for drivers
Wertz, Jérôme ULg; François, Clémentine ULg; Verly, Jacques ULg

Poster (2014, July)

Drowsiness is a major cause of various types of accidents, and particularly of driving accidents. Scientific studies report that drowsiness would be responsible for 20 to 30% of driving accidents ... [more ▼]

Drowsiness is a major cause of various types of accidents, and particularly of driving accidents. Scientific studies report that drowsiness would be responsible for 20 to 30% of driving accidents. Drowsiness can result from, among others, sleep deprivation, sleep disorders, alcohol, some medications, or performing a monotonous task. While all persons are likely to be drowsy at some point during the day, some persons are more prone than others to being drowsy at almost any time of the day; e.g. 6 to 11% of the population suffers from severe chronic excessive daytime sleepiness. Three main classes of methods can be used to characterize the level of drowsiness of a driver without disturbing him. These classes are respectively related to vehicle behavior (e.g. via lateral movements), driver behavior (e.g. via steering wheel movements), and driver physiological state (e.g. via eye movements). Since drowsiness is a physiological state, it seems particularly meaningful to use physiology-based methods to characterize it. Among these, the most significant ones rely on polysomnography and/or oculography. Polysomnography is viewed by some practitioners as the reference in the domain, but it is very sensitive to artifacts, and it is not very practical for use while driving. Ocular parameters are recognized to be good and reliable physiological indicators of drowsiness, and, thus, oculography seems to be the most sensible way to characterize drowsiness in practice. We have thus developed an experimental, fully automatic drowsiness monitoring system (software/algorithms) based on the physiological state of a person. This system uses ocular parameters extracted from images of the eye (i.e. photooculography) to determine a level of drowsiness on a continuous numerical scale from 0 to 10, with 0 corresponding to "very awake" (or "very vigilant") and 10 to "very drowsy". The ultimate goal of this system is to prevent drowsiness-related accidents for driving and other applications. The reported study shows that our system exhibits promising capability for road safety. Fourteen healthy volunteers (7 M, 7 F, mean age 23.7, range 21-33 years) participated in an experiment in a driving simulator, where they were asked to perform three driving sessions/runs (two of 45 minutes and one of 60 minutes) in different sleep-deprivation conditions (with up to 28 hours of complete sleep deprivation). During each session, we recorded both a high frame rate video of one eye and a set of driving parameters. Subsequently, for each successive minute in the session, we used our algorithms to extract ocular parameters from the video images and to produce a level of drowsiness, and we computed the standard deviation of lateral position (SDLP) from the driving parameters. The results show (1) that the (computed) SDLP increases when the (computed) level of drowsiness increases, and (2) that the level of drowsiness increases when the level of sleep deprivation increases. These results indicate that our algorithms for producing a level of drowsiness work in a meaningful way. The experiment protocol was approved by the Ethics Committee of our university. [less ▲]

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See detailCollapsing and reswelling kinetics of thermoresponsive polymers on surfaces: a matter of confinement and constraints
Willet, Nicolas ULg; Gabriel, Sabine ULg; Jérôme, Christine ULg et al

in Soft Matter (2014), 10

We report on the collapsing and reswelling ability of grafted poly(methyl vinyl ether) chains of different molecular architectures. In order to study the influence of constraints and confinement of the ... [more ▼]

We report on the collapsing and reswelling ability of grafted poly(methyl vinyl ether) chains of different molecular architectures. In order to study the influence of constraints and confinement of the chains, the polymer was grafted onto AFM tips, as a model of a curved nano-sized surface, and onto macroscopic silicon substrates for comparison purposes. AFM-based force spectroscopy experiments were performed to characterise at the nanoscale the temperature-dependent collapsing process and the reversibility to the swollen state on both substrates. The reversible character of the thermoresponsive transition and its kinetics were shown to greatly depend on the polymer architecture and the constraints encountered by the chains. [less ▲]

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See detailExperimental modal analysis of a beam travelled by a moving mass using Hilbert Vibration Decomposition
Bertha, Mathieu ULg; Golinval, Jean-Claude ULg

Scientific conference (2014, July)

In this paper the problem of modal identification of time-varying system is investigated. To do so, a technique based on the sifting process of the Hilbert Vibration Decomposition (HVD) method is ... [more ▼]

In this paper the problem of modal identification of time-varying system is investigated. To do so, a technique based on the sifting process of the Hilbert Vibration Decomposition (HVD) method is presented. The key idea is to estimate the instantaneous frequency of the dominant mode, to extract its corresponding component by demodulation of the recorded signals and then to iterate with the subsequent dominant mode. In the case of multiple recorded signals, a source separation method is used as a preprocessing step to facilitate the identification of the instantaneous frequency for the following demodulation step. To illustrate the method, an experimental set-up consisting in a beam travelled by a non negligible mass is considered. The whole structure is randomly excited during the travel of the mass and some responses on the beam are recorded. [less ▲]

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See detailEtude des propriétés de surface et techno-fonctionnelles des fractions protéose-peptones
Karamoko, Gaoussou ULg

Doctoral thesis (2014)

The total proteose-peptone fractions are complex heterogeneous mixture of thermoresistant proteins of whey. The general objective of this work was to contribute to a better knowledge and understanding of ... [more ▼]

The total proteose-peptone fractions are complex heterogeneous mixture of thermoresistant proteins of whey. The general objective of this work was to contribute to a better knowledge and understanding of surface properties and techno-functional properties (foaming and emulsifying properties) and well as setting a relationship between the different properties. In this work, PPT fractions were extracted according to a classical approach and other industrially transposable by considering respectively the skimmed UHT milk and whey protein concentrate (WPC) as raw materials. The using of such both sources allowed to highlight the fundamental differences in the composition of the extracts of PPT. This has begotten a direct impact on the surfactant properties of the PPT. It has been therefore established that these differences at interfaces can have major consequences on their techno-functional behavior. This study also made it possible to determine the contribution of components especially non-hydrophobic and hydrophobic fractions in the interfacial behavior of PPT and the influence of pH, protein concentration, source and method of extraction. The setting in relationship of properties showed the existence of some statistically significant correlations between the interfacial parameters and, foaming and emulsifying properties. It will be therefore possible to predict the behavior of techno-functional PPT from some physico-chemical parameters. Finally, this study also showed that PPT fractions can be used as techno-functional agents in various food formulations based foams or emulsions. [less ▲]

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See detailThe Amik Lake in Southern Turkey over the last 4000 years, a new paleoseismological record of ruptures along the Northern Dead Sea Fault
Hubert, Aurelia ULg; El Ouahabi, Meriam ULg; Lebeau, Hèlène et al

Poster (2014, June 30)

The study focuses on the sedimentary record of the Amik Lake occupying the central part of a pull-apart basin. The Basin is crossed by The Dead Sea Fault (DSF), a major neotectonic structure in the Middle ... [more ▼]

The study focuses on the sedimentary record of the Amik Lake occupying the central part of a pull-apart basin. The Basin is crossed by The Dead Sea Fault (DSF), a major neotectonic structure in the Middle East extending from the Red Sea in the south to the East Anatolian Fault Zone in the north. Around the Amik Basin, continuous human occupation is attested since 6000-7000 BC. Indeed the low-lying Amuq plain is covered by tell settlements first explored by Robert Braidwood in the 1930s. Our objective in this presentation is to look at major paleo-environmental changes recorded in the Amik Lake over the last 4000 years and in particular its potential paleoseimic sedimentary record. The lake has been drained and progressively dried up since the mid-50s so that it is not watered during the summer season and constitutes a unique opportunity to collect sediment records. Sediments were collected at 1 cm to 2 cm intervals in a trench and in cores up to a depth of 5 meters in the clay deposits. A diverse array of complementary methods is applied to study the records: magnetic susceptibility, grain size, organic matter and inorganic carbon (L.O.I), XRD mineralogy, XRF geochemistry, carbon geochemistry and clay mineralogy. The age of the record is constrained combining radionuclide and radiocarbon dating. The sedimentary record shows large earthquake related structural disturbances and smaller siliciclastic sedimentary events. The siliciclastic input would be related to enhanced detritical sedimentation related to earthquake shaking. The latter is further investigated looking at intensities and shake maps related to the last 19th century M>7 earthquakes in the area and landslide prone area in the lake catchment. [less ▲]

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See detailCharge Migration in the Bifunctional PENNA Cation Induced and Probed by Ultrafast Ionization: A Dynamical Study.
Mignolet, Benoît ULg; Levine, R. D.; Remacle, Françoise ULg

in Journal of Physics : B Atomic Molecular & Optical Physics (2014), 47

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See detailWorkshop on Pitch Analysis for Singing
Larrouy, Pauline ULg

Conference (2014, June 28)

Two methods are actually used in order to determine if a vocal performance is “in tune” or “out of tune”, to better understand the causes of poor-pitch singing or to evaluate the quality/progression of a ... [more ▼]

Two methods are actually used in order to determine if a vocal performance is “in tune” or “out of tune”, to better understand the causes of poor-pitch singing or to evaluate the quality/progression of a singer. The "subjective" method makes use of judges whereas the "objective" method uses computer tools to perform pitch analysis and to estimate the accuracy of sung performances. While the first method allows a rapid assessment, it lacks precision, which explains that the “objective” method seems currently preferred. However, several computer tools are available and each laboratory has its preference. In addition, the analytical procedure will depend on the purpose and data of the study. This workshop aims to provide an overview of the tools available and to discuss the advantages and limitations of existing methods. [less ▲]

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See detailPitch fluctuations in accurate and inaccurate singers: are they the same?
Larrouy, Pauline ULg; Pfordresher, Peter Q

Conference (2014, June 28)

The research presented here attempts to explore the fine-control of pitch during singing among accurate occasional singers and individuals whose singing reflects a Vocal Pitch Imitation Deficit (VPID ... [more ▼]

The research presented here attempts to explore the fine-control of pitch during singing among accurate occasional singers and individuals whose singing reflects a Vocal Pitch Imitation Deficit (VPID). Most past research addresses individual differences at the level of entire sung notes or melodies. By contrast, in the present research we addressed whether VPID singers differ from accurate singers with respect to the way to reach, maintain, and stop a sung tone. In order to describe the “scoops” at the beginning and ends of tone, as well as other forms of instability, we adapted the model of Large et al. (2002), originally designed to model entrainment of timing during synchronization. This model was applied to 1461 notes performed by 12 VPID and 17 accurate singers from the database of Pfordresher and Mantell (2014). Finally, the parameter values across the VPID and accurate singers were compared. The results showed that the model fits tones performed by accurate and VPID singers similarly well. As expected, the median pitch across the entire sung note deviated from the target to imitate for VPID singers; at the same time, the proportion of these deviations that were overshoots (“sharp”) versus undershoots (“flat”) were the same for VPID and accurate singers (2/3rd under and 1/3rd above). Thus accurate and VPID singers differ in the magnitude but not the type of overall deviation they exhibit. Whereas no difference occurred between the singers regarding the direction of the scoop (up or down) at the start and the end of the tone, the amplitude of the scoops was significantly different between VPID and accurate singers. The present study highlights the difficulty of VPID singers to reach and stop a sung tone, which supports the hypothesis of a fine motor control deficit in this population. Furthermore, the pitch fluctuations described by the model would have to be investigated in research on pitch accuracy perception. [less ▲]

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