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See detailA New Wavelet-Based Mode Decomposition for Oscillating Signals and Comparison with the Empirical Mode Decomposition
Deliège, Adrien ULg; Nicolay, Samuel ULg

in Information Technology: New Generations (2016, April)

We introduce a new method based on wavelets (EWMD) for decomposing a signal into quasi-periodic oscillating components with smooth time-varying amplitudes. This method is inspired by both the “classic” ... [more ▼]

We introduce a new method based on wavelets (EWMD) for decomposing a signal into quasi-periodic oscillating components with smooth time-varying amplitudes. This method is inspired by both the “classic” wavelet-based decomposition and the empirical mode decomposition (EMD). We compare the reconstruction skills and the period detection ability of the method with the well-established EMD on toys examples and the ENSO climate index. It appears that the EWMD accurately decomposes and reconstructs a given signal (with the same efficiency as the EMD), it is better at detecting prescribed periods and is less sensitive to noise. This work provides the first version of the EWMD. Even though there is still room for improvement, it turns out that preliminary results are highly promising. [less ▲]

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See detail[Beamer] A New Wavelet-Based Mode Decomposition for Oscillating Signals and Comparison with the Empirical Mode Decomposition
Deliège, Adrien ULg; Nicolay, Samuel ULg

Conference (2016, April)

We introduce a new method based on wavelets (EWMD) for decomposing a signal into quasi-periodic oscillating components with smooth time-varying amplitudes. This method is inspired by both the “classic” ... [more ▼]

We introduce a new method based on wavelets (EWMD) for decomposing a signal into quasi-periodic oscillating components with smooth time-varying amplitudes. This method is inspired by both the “classic” wavelet-based decomposition and the empirical mode decomposition (EMD). We compare the reconstruction skills and the period detection ability of the method with the well-established EMD on toys examples and the ENSO climate index. It appears that the EWMD accurately decomposes and reconstructs a given signal (with the same efficiency as the EMD), it is better at detecting prescribed periods and is less sensitive to noise. This work provides the first version of the EWMD. Even though there is still room for improvement, it turns out that preliminary results are highly promising. [less ▲]

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See detailMars Topography Investigated Through the Wavelet Leaders Method: a Multidimensional Study of its Fractal Structure
Deliège, Adrien ULg; Kleyntssens, Thomas ULg; Nicolay, Samuel ULg

Poster (2016, April)

This work examines the scaling properties of Mars topography through a wavelet-based formalism. We conduct exhaustive one-dimensional (both longitudinal and latitudinal) and two-dimensional studies based ... [more ▼]

This work examines the scaling properties of Mars topography through a wavelet-based formalism. We conduct exhaustive one-dimensional (both longitudinal and latitudinal) and two-dimensional studies based on Mars Orbiter Laser Altimeter (MOLA) data using the multifractal formalism called Wavelet Leaders Method (WLM). This approach shows that a scale break occurs at approximately 15 km, giving two scaling regimes in both 1D and 2D cases. At small scales, these topographic profiles mostly display a monofractal behavior while a switch to multifractality is observed in several areas at larger scales. The scaling exponents extracted from this framework tend to be greater at small scales. In the 1D context, these observations are in agreement with previous works and thus suggest that the WLM is well-suited for examining scaling properties of topographic fields. Moreover, the 2D analysis is the first such complete study to our knowledge. It gives both a local and global insight on the scaling regimes of the surface of Mars and allows to exhibit the link between the scaling exponents and several famous features of the Martian topography. These results may be used as a solid basis for further investigations of the scaling laws of the Red planet and show that the WLM could be used to perform systematic analyses of the surface roughness of other celestial bodies. [less ▲]

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See detailPrevalence and determinants of vitamin D deficiency in healthy French adults: the VARIETE study
Souberbielle; Massart, Catherine; Brailly-Tabard, Sylvie et al

in Endocrine (2016)

The U.S. Institute of Medicine considers that a serum 25-hydroxyvitamin D (25OHD) concentration >20 ng/mL corresponds to optimal vitamin D status in the general population. Old studies of vitamin D status ... [more ▼]

The U.S. Institute of Medicine considers that a serum 25-hydroxyvitamin D (25OHD) concentration >20 ng/mL corresponds to optimal vitamin D status in the general population. Old studies of vitamin D status in the French general population have demonstrated high prevalence of insufficiency. We measured serum 25OHD, 1,25(OH)2D, PTH, calcium, phosphorus, and creatinine levels in 892 French Caucasian healthy subjects (463 men, 429 women) aged from 18 to 89 years. The 25OHD concentration was similar in men (24.1 ± 8.2 ng/mL) and women (23.4 ± 8.0 ng/mL). 25OHD concentrations of <10, <12, <20, and <30 ng/mL were found in respectively 6.3, 9.9, 34.6, and 80.3 % of subjects. Residence in northern France (odds ratio [OR] 1.91), blood sampling between January and March (OR 7.74), BMI ≥24 kg/m2 (OR 1.81), and age 60 years or more (OR 1.99) were significant determinants of hypovitaminosis D (25OHD <20 ng/mL). The serum 25OHD level correlated positively with 1,25(OH)2D and negatively with PTH. 25OHD values below 20 ng/mL were associated with lower 1,25(OH)2D levels, and 25OHD values below 27 ng/mL were associated with higher PTH levels. Many French healthy adults have a 25OHD concentration <20 ng/mL, especially during winter months. Actions to improve the vitamin D status of the French general population are urgently needed. [less ▲]

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See detailUtopie et anticipation
Stienon, Valérie ULg

Book published by Revue Textyles - Éditions Samsa (2016)

Prolifique dans les littératures de l’imaginaire, la Belgique présente pourtant une inconnue à propos du récit d’anticipation. De la fin du monde de Rosny aîné à celle de Luc Dellisse, des aventures ... [more ▼]

Prolifique dans les littératures de l’imaginaire, la Belgique présente pourtant une inconnue à propos du récit d’anticipation. De la fin du monde de Rosny aîné à celle de Luc Dellisse, des aventures spatiales de Bob Morane à la découverte des Cités obscures, du roman scientifique de Henri-Jacques Proumen aux technosciences de Gilbert Hottois, l’anticipation excède les caractéristiques de la science-fiction, croise plus d’une fois l’utopie et redéfinit les rapports entre réel et fiction en une pluralité de mondes possibles. Elle pose des questions cruciales lorsqu’on prend la peine de considérer ses réalisations dans la littérature belge francophone : quels sont les auteurs, les éditeurs et les supports concernés ? existe-t-il des thèmes spécifiques ? quels imaginaires ces fictions privilégient-elles ? comment les genres investis interfèrent-ils avec le merveilleux scientifique, le surréalisme ou le réalisme magique ? En associant des études de cas à une réflexion d’ensemble, les contributions rassemblées dans ce numéro proposent le premier état des lieux d’une production hybride encore peu considérée. Il s’agit d’éclairer la diversité qui caractérise l’anticipation belge, mais aussi de mettre en évidence les raisons de sa faible reconnaissance esthétique et de poser les jalons d’une histoire littéraire capable de saisir des dynamiques multiples de légitimation. [less ▲]

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See detailUne école belge de l’anticipation ?
Stienon, Valérie ULg

in Textyles : Revue des Lettres Belges de Langue Française (2016), 48

Prolifique dans les littératures de l'imaginaire, la Belgique présente pourtant une inconnue s'agissant du récit d'anticipation. Il suffit pour en prendre la mesure de comparer les situations respectives ... [more ▼]

Prolifique dans les littératures de l'imaginaire, la Belgique présente pourtant une inconnue s'agissant du récit d'anticipation. Il suffit pour en prendre la mesure de comparer les situations respectives de ces deux « genres » réputés voisins que sont la science-fiction et le fantastique. Celui-ci a été érigé en emblème des terres du syncrétisme et de l'étrange, tandis que celle-là a souffert d'expressions isolées et de dénis compliquant sa réception. La situation de l'anticipation est plus complexe encore : souvent rattachée à la science-fiction, dont elle constituerait une étape archaïque ou protohistorique, elle ne se confond pas tout à fait avec elle. Ne se définissant pas exclusivement par les thématiques scientifiques ou extraterrestres, ni même par la seule dimension futuriste, l'anticipation se donne pour objet une exploration imaginaire des mondes possibles. Cette exploration s'est manifestée plus d'une fois avec succès dans l'histoire des lettres belges, des fictions de Rosny aîné (Les Xipéhuz, La Force mystérieuse, Les Navigateurs de l'infini) aux mondes parallèles créés par François Schuiten et Benoît Peeters, des aventures spatiales de Bob Morane aux technosciences de Gilbert Hottois. Mais quel dénominateur commun peut-on trouver à ce corpus disparate ? Et comment faire l'archéologie d'une production qui a trouvé des expressions variées et originales malgré une généricité hybride et l'absence de représentant majeur ? [less ▲]

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See detailAnticipation et mondes parallèles. Entretien avec Benoît Peeters et François Schuiten
Stienon, Valérie ULg

in Textyles : Revue des Lettres Belges de Langue Française (2016), 48

Benoît Peeters et François Schuiten ont aimablement accepté l’invitation de l’entretien, qui a eu lieu le 12 janvier 2015 au café Le Wilson en face du Palais de Chaillot où se tient l’exposition Revoir ... [more ▼]

Benoît Peeters et François Schuiten ont aimablement accepté l’invitation de l’entretien, qui a eu lieu le 12 janvier 2015 au café Le Wilson en face du Palais de Chaillot où se tient l’exposition Revoir Paris. [less ▲]

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See detailTaller trees, denser stands and greater biomass in semi-deciduous than in evergreen lowland central African forests
Fayolle, Adeline ULg; Loubota Panzou, Grâce Jopaul ULg; Drouet, Thomas et al

in Forest Ecology & Management (2016), 374

Accurate height-diameter allometry is crucial for the estimation of forest biomass and carbon stocks. Tree height measurements over a large range of diameters and species are urgently needed in the ... [more ▼]

Accurate height-diameter allometry is crucial for the estimation of forest biomass and carbon stocks. Tree height measurements over a large range of diameters and species are urgently needed in the tropics, specifically in central Africa, for the development of locally derived height-diameter allometric equations and the conversion of forest inventory data into biomass estimates, and for the validation of remotely sensed canopy height that mostly rely on a few specific field sites. In this study, we aimed to identify the variation in height-diameter allometry of tropical trees between forest types and among species in central Africa, and we examined the consequences for biomass estimation. Height and diameter were measured for a total of 521 trees over a large range of diameters in two forest types in southern Cameroon, 10–240 cm in the evergreen forest and 11–182 cm in the semi-deciduous forest. A total of ten allometric models including asymptotic and non-asymptotic models were fitted to the heightdiameter data. Measured tree diameters, grouped into 10 cm wide diameter classes up to 150, from commercial forest inventory data (0.5 ha plots, n = 2101 and n = 5152, respectively in the evergreen and in the semi-deciduous forests) were converted into biomass estimates using general allometric models with and without including our site-specific height-diameter allometry. Though debated in the literature, our results supported a saturation of tree height with tree diameter both at site and species level, with asymptotic models better depicting the height-diameter allometry. Height-diameter allometry significantly differed between forest types and these local height-diameter equations also differed from published equations. For a given diameter, trees tended to be taller in the semi-deciduous forest than in the evergreen forest, as already reported between moist and wet forests in pantropical studies. Similar trends were reported within species for the three species shared by both forest types, suggesting an environmental control of tree allometry. Because of the low performance of the bioclimatic stress variable to predict tree height and of the slight soil differences between the two forest types, the environmental determinants of height-diameter allometry remain to be explored. In addition to tree allometry variation, structural differences (basal area and density) were also identified between the two forest types using commercial forest inventory data at genus level, and both allometry and forest structure (taller trees and denser stands) contributed to the greater biomass per hectare of the semi-deciduous forest. [less ▲]

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See detailInfluence of plant roots on electrical resistivity measurements of cultivated soil columns
Maloteau, Sophie ULg; Blanchy, Guillaume ULg; Javaux, Mathieu et al

Poster (2016, April)

The goals of this experiment are to quantify the effect of plant roots on electrical resistivity of the soil subsurface and to map a plant roots system in space and time with ERT technique in a soil ... [more ▼]

The goals of this experiment are to quantify the effect of plant roots on electrical resistivity of the soil subsurface and to map a plant roots system in space and time with ERT technique in a soil column. For this research, it is assumed that roots system affect the electrical properties of the rhizosphere. Indeed the root activity (by transporting ions, releasing exudates, changing the soil structure,…) will modify the rhizosphere electrical conductivity (Lobet G. et al, 2013). This experiment is included in a bigger research project about the influence of roots system on geophysics measurements. Measurements are made on cylinders of 45 cm high and a diameter of 20 cm, filled with saturated loam on which seeds of Brachypodium distachyon (L.) Beauv. are sowed. Columns are equipped with electrodes, TDR probes and temperature sensors. Experiments are conducted at Gembloux Agro-Bio Tech, in a growing chamber with controlled conditions: temperature of the air is fixed to 20°C, photoperiod is equal to 14 hours, photosynthetically active radiation is equal to 200 µmol m-2s-1, and air relative humidity is fixed to 80 %. Columns are fully saturated the first day of the measurements duration then no more irrigation is done till the end of the experiment. [less ▲]

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See detailExposition "Magie et raison. Elisa von der Recke et l'affaire Cagliostro"
Leyh, Valérie ULg

in Culture, le Magazine Culturel de l'Université de Liège (2016)

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See detailUnderground Pumped Storage Hydropower using abandoned open pit mines: influence of groundwater seepage on the system efficiency
Pujades, Estanislao ULg; Bodeux, Sarah ULg; Orban, Philippe ULg et al

Poster (2016, April)

Pumped Storage Hydropower (PSH) plants can be used to manage the production of electrical energy according to the demand. These plants allow storing and generating electricity during low and high demand ... [more ▼]

Pumped Storage Hydropower (PSH) plants can be used to manage the production of electrical energy according to the demand. These plants allow storing and generating electricity during low and high demand energy periods, respectively. Nevertheless, PSH plants require a determined topography because two reservoirs located at different heights are needed. At sites where PSH plants cannot be constructed due to topography requirements (flat regions), Underground Pumped Storage Hydropower (UPSH) plants can be used to adjust the electricity production. These plants consist in two reservoirs, the upper one is located at the surface (or at shallow depth) while the lower one is underground (or deeper). Abandoned open pit mines can be used as lower reservoirs but these are rarely isolated. As a consequence, UPSH plants will interact with surrounding aquifers exchanging groundwater. Groundwater seepage will modify hydraulic head inside the underground reservoir affecting global efficiency of the UPSH plant. The influence on the plant efficiency caused by the interaction between UPSH plants and aquifers will depend on the aquifer parameters, underground reservoir properties and pumping and injection characteristics. The alteration of the efficiency produced by the groundwater exchanges, which has not been previously considered, is now studied numerically. A set of numerical simulations are performed to establish in terms of efficiency the effects of groundwater exchanges and the optimum conditions to locate an UPSH plant. [less ▲]

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See detailA first database for landslide studies in densely urbanized areas of the intertropical zone: Abidjan, Côte d’Ivoire
Gnagne, Lorng Frédéric ULg

Conference (2016, April)

A detail first database for landslide studies in densely urbanized areas have been produced in two prone-areas which are mainly affected. During rain season, landslides occurred in Abobo and Attecoube ... [more ▼]

A detail first database for landslide studies in densely urbanized areas have been produced in two prone-areas which are mainly affected. During rain season, landslides occurred in Abobo and Attecoube causing social and economic damages. Studies on landslides have been restricted or often simply lacking. Landslides were located by GPS and tentatively dated through inquiries during the survey. While 12 landslides were accurately dated that way from the main rain seasons of 2013 to 2015, newspapers analysis and municipal archive consultation allowed us to assign a part of the rest to the last decade. Field inquiries were also used to collect information about fatalities and the local conditions of landsliding. This first landslide inventory in Attecoube provides clues about the main potential controls on landsliding, natural and anthropogenic, and will help define adequately anthropogenic variables to be used in the susceptibility modelling. [less ▲]

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See detailExperimental Tests and Numerical Modelling on Slender Steel Columns at High Temperatures
Franssen, Jean-Marc ULg; Zhao, Bin; Gernay, Thomas ULg

in Journal of Structural Fire Engineering (2016), 7(1), 30-40

Purpose The purpose of this paper is to gain from experimental tests an insight into the failure mode of slender steel columns subjected to fire. The tests will also be used to validate a numerical model ... [more ▼]

Purpose The purpose of this paper is to gain from experimental tests an insight into the failure mode of slender steel columns subjected to fire. The tests will also be used to validate a numerical model. Design/methodology/approach A series of experimental fire tests were conducted on eight full-scale steel columns made of slender I-shaped Class 4 sections. Six columns were made of welded sections (some prismatic and some tapered members), and two columns were made of hot rolled sections. The nominal length of the columns was 2.7 meters with the whole length being heated. The load was applied at ambient temperature after which the temperature was increased under constant load. The load was applied concentrically on some tests and with an eccentricity in other tests. Heating was applied by electrical resistances enclosed in ceramic pads. Numerical simulations were performed with the software SAFIR® using shell elements. Findings The tests have allowed determining the appropriate method of application of the electrical heating system for obtaining a uniform temperature distribution in the members. Failure of the columns during the tests occurred by combination of local and global buckling. The numerical model reproduced correctly the failure modes as well as the critical temperatures. Originality/value The numerical model that has been validated has been used in subsequent parametric analyses performed to derive design equations to be used in practice. This series of test results can be used by the scientific community to validate their own numerical or analytical models for the fire resistance of slender steel columns. [less ▲]

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See detailEntretenir le souvenir de Charlemagne en Belgique. Regards croisés de médiévistes et de contemporanéistes
Close, Florence ULg; Lanneau, Catherine ULg

Book published by Société pour le progrès des études philologiques et historiques - extrait de la Revue Belge de Philologie et d'Histoire, t. 93 (2015/3-4) (2016)

À l’heure des grandes revendications identitaires d’inspiration romantique, le jeune état belge a fermement bataillé pour asseoir et renforcer un sentiment national propre. Il a cherché dans le passé le ... [more ▼]

À l’heure des grandes revendications identitaires d’inspiration romantique, le jeune état belge a fermement bataillé pour asseoir et renforcer un sentiment national propre. Il a cherché dans le passé le plus lointain les arguments susceptibles de saper certaines accusations tendant à présenter la Belgique comme un état sans nation, une construction artificielle. Charlemagne fut l’un des maillons de la chaîne. Ce volume constitue les actes d'une journée d'étude organisée à l'occasion du 1200 anniversaire de sa mort en vue de confronter les recherches de spécialistes des temps récents aux remarques et questionnements de carolingianistes avertis. [less ▲]

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See detailLa figure de Charlemagne dans la vulgarisation historique belge. Exemples choisis
Lanneau, Catherine ULg

in Revue Belge de Philologie et d'Histoire (2016), 93(2015/3-4),

Common ancestor of the Belgians, civilizing Christian emperor, father of Europe: these are some of the political (polemical) ways used to describe Charlemagne in the Belgium. This contribution seeks to ... [more ▼]

Common ancestor of the Belgians, civilizing Christian emperor, father of Europe: these are some of the political (polemical) ways used to describe Charlemagne in the Belgium. This contribution seeks to decipher and interpret these descriptions. What do we remember, or want to remember, from the origins and actions of the Carolingian emperor to show to the Belgians? Without pretending to be complete, certain marked tendencies and manifest evolutions are pointed out, found in the popular historical books for adults and children. Two key periods are defined: the first decades of the Belgian independence and the period after 1945. The final results are mixed: Charlemagne was certainly an icon, but in each of his avatars, failed to convince or win the majority support. His best enduring memory seems to be found today in the Euregion Meuse-Rhine, mostly because of the commercial and touristic value. [less ▲]

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See detailMise au point d’une nouvelle méthode de diagnostic des allergènes du froment par Western blot 2D
BERTHOLET, Catherine ULg; GADISSEUR, Romy ULg; Quinting, Birgit

in Revue Française d'Allergologie (2016, April), 56(3), 284

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See detailClinically Relevant Optical Properties of Bifocal, Trifocal, and Extended Depth of Focus Intraocular Lenses
Gatinel, Damien; Loicq, Jerôme ULg

in Journal of Refractive Surgery (2016), 32(4), 273-280

PURPOSE: To experimentally compare the optical performance of three types of hydrophobic intraocular lenses (IOLs): extended depth of focus, bifocal, and trifocal. METHODS: The tested IOLs were: TECNIS ... [more ▼]

PURPOSE: To experimentally compare the optical performance of three types of hydrophobic intraocular lenses (IOLs): extended depth of focus, bifocal, and trifocal. METHODS: The tested IOLs were: TECNIS ZMB00 (bifocal; Abbott Medical Optics, Abbott Park, IL), TECNIS Symfony ZXR00 (extended depth of focus; Abbott Medical Optics), and FineVision GFree hydrophobic (trifocal; PhysIOL, Liège, Belgium). Their surface topography was analyzed by optical microscopy. Modulation transfer function (MTF) and spherical aberrations were determined on optical bench for variable pupil apertures and with two cornea models (0 μm and +0.28 μm). United States Air Force target imaging was analyzed for different focal points (near, intermediate, and far). Point spread function (PSF) and halos were quantified and compared. RESULTS: The three lenses presented step-like optic topography. For a pupil size of 3 mm or greater, clearly distinctive MTF peaks were observed for all lenses: two peaks for the extended depth of focus and bifocal lenses with +1.75 and +4.00 diopters (D) addition, respectively, and three peaks for the trifocal lens with +1.75 and +3.50 addition for intermediate and near vision, respectively. The extended depth of focus and bifocal lens had slightly higher MTF at best focus with the +0.28 μm cornea model than with the 0 μm model, whereas the trifocal lens was likely to be more independent of the corneal spherical aberrations.CONCLUSIONS: It appears that the three lenses rely on light diffraction for their optical performance, presenting halos with comparable intensities. For small pupil apertures (< 3 mm), the MTF peaks for the far and intermediate focal distances of the trifocal and extended depth of focus lenses overlap, but the trifocal lens presented an additional MTF peak for the near focal points. [less ▲]

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