Publications ORBi OA
Bookmark and Share    
Full Text
See detailGrammaire du compromis après la révolution tunisienne.
Verjans, Pierre ULg

Conference given outside the academic context (2017)

Le système belge a fabriqué du compromis sans les institutions de consensus identifiées par Arend Lijphart en 1830; en 2007, malgré la présence des institutions de consensus, il ne parvient à créer du ... [more ▼]

Le système belge a fabriqué du compromis sans les institutions de consensus identifiées par Arend Lijphart en 1830; en 2007, malgré la présence des institutions de consensus, il ne parvient à créer du consensus qu'après 5 ans de crises. Le référentiel compte donc au moins autant que les institutions.Par ailleurs, on peut analyser les syntagmes politiques des divers moments de la révolution tunisienne grâce à une grille d'analyse structurale. [less ▲]

Detailed reference viewed: 57 (1 ULg)
Full Text
See detailLa nature des intérêts spécifiques distingue les personnes avec et sans retard de langage.
Chiodo, Liliane ULg; Majerus, Steve ULg; Eusèbe, Sandrine et al

Poster (2017, May 20)

Detailed reference viewed: 46 (0 ULg)
Full Text
See detailAnalysing operando Mössbauer spectra of battery materials: a chemometric approach to the study of NaFeO2 as positive electrode material for Na-ion batteries
Stievano, Lorenzo; Sougrati, Moulay Tahar; Darwiche, Ali et al

Conference (2017, May 19)

Among the possible positive electrode materials for Na-ion batteries, iron-based oxides have been regarded as promising solids for the reversible insertion/deinsertion of Na on the basis of their ... [more ▼]

Among the possible positive electrode materials for Na-ion batteries, iron-based oxides have been regarded as promising solids for the reversible insertion/deinsertion of Na on the basis of their abundance in the Earth’s crust. In particular, O3-type NaFeO2, easily prepared from the reaction of iron oxide and Na2CO3 at 600°C, has been identified as the most interesting one from the viewpoint of both gravimetric and volumetric energy density.[1–3] Na/NaFeO2 cells cycle through a relatively flat potential plateau between 3.3 and 3.4 V vs. Na+/Na, commonly associated with the Fe4+/Fe3+ redox couple. However, if cycling is extended above 3.5 V, other irreversible reaction plateaux appear, which completely inactivate the material. 57Fe Mössbauer spectroscopy is thus a method of choice for the study of both (1) the cycling mechanism and (2) the irreversible reactions occurring above 3.5 V. In this work, operando 57Fe Mössbauer spectra were collected during the electrochemical cycling of NaFeO2 vs. Na metal using a specifically designed in situ cell,[4] and analysed using an alternative and innovating data analysis approach based on chemometric tools such as Principal Component Analysis (PCA) and multivariate curve resolution (MCR).[5,6] This approach, which allows the unbiased extraction of all possible information from the operando data, enabled the stepwise reconstruction of the “real” spectral components occurring during the cycling of NaFeO2. In this way, a clear description of the electrochemically active iron species could be obtained, allowing a clearer comprehension of the cycling mechanisms of this material vs. sodium. Références : [1] J. Zhao, L. Zhao, N. Dimov, O. Shigeto, T. Nishida, J. Electrochem. Soc. 160 (2013) A3077. [2] H. Yoshida, N. Yabuuchi, S. Komaba, in:, ECS Meet. Abstr. MA2012-02, ECS, Honolulu, 2011, p. 1850. [3] P. Barpanda, Chem. Mater. 28 (2016) 1006. [4] J.-B. Leriche, S. Hamelet, J. Shu, M. Morcrette, C. Masquelier, G. Ouvrard, M. Zerrouki, P. Soudan, S. Belin, E. Elkaïm, F. Baudelet, J. Electrochem. Soc. 157 (2010) A606. [5] R. Tauler, Chemom. Intell. Lab. 30 (1995) 133. [6] A. Voronov, A. Urakawa, W. van Beek, N.E. Tsakoumis, H. Emerich, M. Rønning, Anal. Chim. Acta 840 (2014) 20. [less ▲]

Detailed reference viewed: 36 (2 ULg)
Full Text
See detailFondements théoriques d’une analyse du lexique
Winand, Jean ULg

Scientific conference (2017, May 19)

Detailed reference viewed: 22 (1 ULg)
Full Text
See detailLa lecture partagée pour améliorer l’entrée dans l’écrit chez des enfants issus de population défavorisée
Maillart, Christelle ULg; Binamé, Florence ULg; Vossius, Line ULg et al

Conference (2017, May 19)

Les enfants issus de populations défavorisées sont à risque de présenter des difficultés d’apprentissage en lecture. Sans intervention appropriée, le décalage entre les performances de ces enfants et leur ... [more ▼]

Les enfants issus de populations défavorisées sont à risque de présenter des difficultés d’apprentissage en lecture. Sans intervention appropriée, le décalage entre les performances de ces enfants et leur pairs persiste voire se creuse avec le temps (Lonigan et al., 2015). Cette communication présente les résultats d’une étude en intervention ciblant la littératie émergente chez de jeunes enfants scolarisés en fin de maternelle. Elle fait partie d’un projet plus large comparant les effets de différentes interventions ciblées 1) sur les précurseurs du calcul, 2) sur des activités psychomotrices ou 3) sur la littératie émergente chez trois groupes d’enfants prése. Pour cette dernière intervention, un groupe de 10 enfants d’âge préscolaire âgés de 51 mois à 70 mois, tous issus d’une école accueillant des enfants issus de milieux socio-économiques faibles, ont participé à une intervention en lecture partagée pendant dix semaines, trente minutes par jour, cinq fois par semaine. La lecture partagée est considérée comme une « bonne pratique » pour le développement de la littératie émergente (National Early Literacy Panel, 2008). Elle cible à la fois des aptitudes concernant le code (conscience phonologique ou connaissance de l’alphabet) et le sens (vocabulaire, syntaxe, grammaire narrative) (Piasta, 2016). Les performances des enfants dans les différentes mesures langagières ou de lecture, évaluées avant et après l’intervention, ont été comparées aux performances obtenues par des enfants ayant participé aux deux autres interventions. Les effets à court terme (pré, post intervention) mais aussi à long terme sur le développement du langage écrit seront présentés, permettant de distinguer des effets d’entrainement spécifique ou plus de stimulation plus globale. [less ▲]

Detailed reference viewed: 26 (0 ULg)
Full Text
See detailDes jeux de doigts pour renforcer les précurseurs des apprentissages scolaire
Dauvister, Estelle; Vossius, Line ULg; Rousselle, Laurence ULg

Poster (2017, May 19)

Detailed reference viewed: 13 (0 ULg)
Full Text
See detailMétacognition lors de la récupération en mémoire chez les patients Alzheimer
Genon, Sarah ULg

Scientific conference (2017, May 19)

Detailed reference viewed: 25 (2 ULg)
Full Text
Peer Reviewed
See detailHealing Effect of Controlled Anti-Electromigration on Conventional and High-Tc Superconducting Nanowires
Baumans, Xavier ULg; Lombardo, Joseph ULg; Brisbois, Jérémy ULg et al

in Small : Nano Micro (2017), 1700384

The electromigration process has the potential capability to move atoms one by one when properly controlled. It is therefore an appealing tool to tune the cross section of monoatomic compounds with ... [more ▼]

The electromigration process has the potential capability to move atoms one by one when properly controlled. It is therefore an appealing tool to tune the cross section of monoatomic compounds with ultimate resolution or, in the case of polyatomic compounds, to change the stoichiometry with the same atomic precision. As demonstrated here, a combination of electromigration and anti-electromigration can be used to reversibly displace atoms with a high degree of control. This enables a fine adjustment of the superconducting properties of Al weak links, whereas in Nb the diffusion of atoms leads to a more irreversible process. In a superconductor with a complex unit cell (La 2−x Ce x CuO 4 ), the electromigration process acts selectively on the oxygen atoms with no apparent modification of the structure. This allows to adjust the doping of this compound and switch from a superconducting to an insulating state in a nearly reversible fashion. In addition, the conditions needed to replace feedback controlled electromigration by a simpler technique of electropulsing are discussed. These findings have a direct practical application as a method to explore the dependence of the characteristic parameters on the exact oxygen content and pave the way for a reversible control of local properties of nanowires. [less ▲]

Detailed reference viewed: 7 (2 ULg)
Full Text
Peer Reviewed
See detailAller au spectacle
Brahy, Rachel ULg

Conference (2017, May 18)

Detailed reference viewed: 17 (0 ULg)
Full Text
See detailMécanismes de vieillissement des anodes à base de FeSn2 pour batteries Li-ion
Chamas, Mohamad; Mahmoud, Abdelfattah ULg; Tang, junlei et al

Poster (2017, May 18)

Les intermétalliques d’étain ont été proposés comme matériaux d’anode pour batteries Li-ion à forte densité d’énergie car leur capacité spécifique est bien supérieure à celle des anodes commerciales à ... [more ▼]

Les intermétalliques d’étain ont été proposés comme matériaux d’anode pour batteries Li-ion à forte densité d’énergie car leur capacité spécifique est bien supérieure à celle des anodes commerciales à base de carbone. Le mécanisme électrochimique est basé sur la transformation irréversible de FeSn2 en un composite formé de nanoparticules de fer et de Li3.5Sn lors de la première lithiation, puis de réactions réversibles modifiant la composition de Li3.5Sn, les particules de fer assurant la dispersion de ces particules à base d’étain [1]. Cependant, nous avons observé que l’électrode lithiée était instable dans le temps conduisant à l’autodécharge progressive de la batterie [2]. Ce phénomène de vieillissement a été caractérisé par spectrométrie Mössbauer du 57Fe et de 119Sn, par spectroscopie d’impédance et par mesures magnétiques (Figure 1). On montre que le composite Fe/Li3.5Sn se délithie progressivement au cours du temps conduisant à un composite faiblement lithié Fe/LixSn avec x<1. Les nanoparticules de fer sont stables et ne réagissent pas avec LixSn. Les atomes de lithium libérés réagissent avec l’électrolyte et modifient la morphologie de la couche SEI (Surface Electrolyte Interphase) située à la surface des particules LixSn du composite.[1] M. Chamas, M. T. Sougrati, C. Reibel, P.E. Lippens, Chem. Mater. 25, 2410 (2015). [2] M. Chamas, A. Mahmoud, J. Tang, S. Panero, M. T. Sougrati, P. E. Lippens, J. Phys Chem. C 121, 217 (2017). [less ▲]

Detailed reference viewed: 15 (2 ULg)
Full Text
See detailStructural and Magnetic Properties of Nanosized strontium Hexaferrite Powders: Experimental and theoretical investigation
Abraime, Brahim; Ait Tamerd, Mohamed; Mahmoud, Abdelfattah ULg et al

Poster (2017, May 18)

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000°C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray ... [more ▼]

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000°C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy (MS) and superconducting quantum interference device magnetometer (SQUID) techniques were used to characterize crystal structure, phase composition, morphology and magnetic properties. TGA gives T=800 °C as beginning of suitable calcination. Hexaferrite structure of single phase is obtained according to XRD results for all samples with crystallite size between 28 nm and 35 nm. SEM images show the growth of grain size with increasing of annealing temperature. (BH)max is calculated based on SQUID results and shows an enhancement between T=800°C and T= 1000°C of 25%. The magnetic properties observed at low temperature are explained and confirmed by ab-initio calculations. [less ▲]

Detailed reference viewed: 22 (2 ULg)
Full Text
See detailApplication of wavelet transforms to geosciences: Extraction of functional and frequential information
Deliège, Adrien ULg

Doctoral thesis (2017)

It is now well-known that there exist functions that are continuous but nowhere differentiable. Still, it appears that some of them are less “irregular” than others. The pointwise regularity of a function ... [more ▼]

It is now well-known that there exist functions that are continuous but nowhere differentiable. Still, it appears that some of them are less “irregular” than others. The pointwise regularity of a function can be characterized by its Hölder exponent at each point. For the sake of practicability, it is more appropriate to determine the “size” of the sets of points sharing a same exponent, through their Hausdorff measure. By doing so, one gets the multifractal spectrum of a function, which characterizes in particular its monofractal or multifractal nature. The first part of this work is based on the so-called “wavelet leaders method” (WLM), recently developed in the context of multifractal analysis, and aims at its application to concrete situations in geosciences. First, we present the WLM and we insist particularly on the major differences between theory and practice in its use and in the interpretation of the results. Then, we show that the WLM turns out to be an efficient tool for the analysis of Mars topography from a unidimensional and bidimensional point of view; the first approach allowing to recover information consistent with previous works, the second being new and highlighting some areas of interest on Mars. Then, we study the regularity of temperature signals related to various climate stations spread across Europe. In a first phase, we show that the WLM allows to detect a strong correlation with pressure anomalies. Then we show that the Hölder exponents obtained are directly linked to the underlying climate and we establish criteria that compare them with their climate characteristics as defined by the Köppen-Geiger classification. On the other hand, the continuous version of the wavelet transform (CWT), developed in the context of time-frequency analysis, is also studied in this work. The objective here is the determination of dominant periods and the extraction of the associated oscillating components that constitute a given signal. The CWT allows, unlike the Fourier transform, to obtain a representation in time and in frequency of the considered signal, which thus opens new research perspectives. Moreover, with a Morlet-like wavelet, a simple reconstruction formula can be used to extract components. Therefore, the second part of the manuscript presents the CWT and focuses mainly on the border effects inherent to this technique. We illustrate the advantages of the zero-padding and introduce an iterative method allowing to alleviate significantly reconstruction errors at the borders of the signals. Then, we study in detail the El Niño Southern Oscillation (ENSO) signal related to temperature anomalies in the Pacific Ocean and responsible for extreme climate events called El Niño (EN) and La Niña (LN). Through the CWT, we distinguish its main periods and we extract its dominant components, which reflect well-known geophysical mechanisms. A meticulous study of these components allows us to elaborate a forecasting algorithm for EN and LN events with lead times larger than one year, which is a much better performance than current models. After, we generalize the method used to extract components by developing a procedure that detects ridges in the CWT. The algorithm, called WIME (Wavelet-Induced Mode Extraction), is illustrated on several highly non-stationary examples. Its ability to recover target components from a given signal is tested and compared with the Empirical Mode Decomposition. It appears that WIME has a better adaptability in various situations. Finally, we show that WIME can be used in real-life cases such as an electrocardiogram and the ENSO signal. [less ▲]

Detailed reference viewed: 67 (33 ULg)
Full Text
See detailElections présidentielles française de 2017: analyse des résultats.
Verjans, Pierre ULg

Conference given outside the academic context (2017)

A la suite d'une campagne électorale particulièrement agitée, les deux principaux partis du pays depuis des décennies ne sont pas parvenus à placer leur candidat au deuxième tour. Les résultats et leurs ... [more ▼]

A la suite d'une campagne électorale particulièrement agitée, les deux principaux partis du pays depuis des décennies ne sont pas parvenus à placer leur candidat au deuxième tour. Les résultats et leurs conséquences méritent une analyse et une réflexion collective. [less ▲]

Detailed reference viewed: 57 (1 ULg)
Full Text
See detailRencontre avec Pascal Matthey
Crucifix, Benoît ULg

Speech/Talk (2017)

Detailed reference viewed: 19 (1 ULg)
Full Text
See detailA Journey Through Julia: A dynamic and fast language
Cuvelier, Thibaut ULg

Speech/Talk (2017)

Usually, dynamic programming languages (like Python, R, or MATLAB) are quite slow when executed, which causes performance problems in many applications. Julia is a blossoming language, both dynamic and ... [more ▼]

Usually, dynamic programming languages (like Python, R, or MATLAB) are quite slow when executed, which causes performance problems in many applications. Julia is a blossoming language, both dynamic and fast, fully open source, with a syntax that is very similar to that of MATLAB. This talk presents briefly Julia and its ecosystem. [less ▲]

Detailed reference viewed: 9 (2 ULg)
Full Text
Peer Reviewed
See detailDefining thermal comfort boundaries for heating and cooling demand estimation in Iran's urban settlements
Roshan, GhR.; Farrokhzad, M.; Attia, Shady ULg

in Building & Environment (2017), 121

Iran has diverse climate variability, comfort boundaries for each geographic region must be defined in order to present current architectural design recommendations and proper mechanical systems design to ... [more ▼]

Iran has diverse climate variability, comfort boundaries for each geographic region must be defined in order to present current architectural design recommendations and proper mechanical systems design to meet building's heating and cooling energy demand. Therefore, two components of the temperature and relative humidity of 148 stations with the longest common statistical period of twenty years (1994–2014), which have been in daily scale were selected to calibrate and redefine the thermal boundary conditions in Iran. Givoni chart was used to define and visualize the bioclimatic conditions in buildings. The results of this study indicate that only 18% of the 148 stations days, falls in the thermal comfort bioclimatic conditions. After calibration of the base comfort temperature, we found that the upper threshold of this component varies from at least 22.62 °C for Ardebil to 25.94 °C for Dorudzan station and the low threshold of this component belongs to Ardebil with at least 20.13 °C up to its maximum value with 22 °C which belongs to Dorudzan. Spatial distribution of cooling and heating days show that their maximum threshold has been for cores in Northeastern half of Iran, Iran's Western half and some Central parts of Iran and the minimum threshold of these two components belongs to the beaches of north and south of the country. The findings present updated thermal comfort boundaries that can be used by architects, engineers and policy makers to achieve, in turn, more energy efficient homes and high quality indoor and outdoor living environments. [less ▲]

Detailed reference viewed: 43 (4 ULg)
Full Text
See detailFish introductions, newt decline and paedomorph extinction
Denoël, Mathieu ULg

Scientific conference (2017, May 16)

Detailed reference viewed: 21 (4 ULg)