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See detailL'affirmation de l'Occident (XIe-XVIIIe s.)
Jadoulle, Jean-Louis ULg; Georges, Jean

Book published by Didier Hatier - 2ème éd. (2014)

Cet ouvrage constitue la nouvelle édition du manuel scolaire édité, sous le même titre, en 2006. Il est toutefois assorti, à présent, d'un manuel numérique enrichi entièrement nouveau.

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See detailA Supervised Machine Learning Approach to Variable Branching in Branch-And-Bound
Marcos Alvarez, Alejandro ULg; Louveaux, Quentin ULg; Wehenkel, Louis ULg

E-print/Working paper (2014)

We present in this paper a new approach that uses supervised machine learning techniques to improve the performances of optimization algorithms in the context of mixed-integer programming (MIP). We focus ... [more ▼]

We present in this paper a new approach that uses supervised machine learning techniques to improve the performances of optimization algorithms in the context of mixed-integer programming (MIP). We focus on the branch-and-bound (B&B) algorithm, which is the traditional algorithm used to solve MIP problems. In B&B, variable branching is the key component that most conditions the efficiency of the optimization. Good branching strategies exist but are computationally expensive and usually hinder the optimization rather than improving it. Our approach consists in imitating the decisions taken by a supposedly good branching strategy, strong branching in our case, with a fast approximation. To this end, we develop a set of features describing the state of the ongoing optimization and show how supervised machine learning can be used to approximate the desired branching strategy. The approximated function is created by a supervised machine learning algorithm from a set of observed branching decisions taken by the target strategy. The experiments performed on randomly generated and standard benchmark (MIPLIB) problems show promising results. [less ▲]

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See detailUse of Time- and Frequency-Domain Approaches for Damage Detection in Civil Engineering Structures
Nguyen, Viet Ha; Mahowald, Jean; Maas, Stefan et al

in Shock and Vibration (2014), 2014

The aim of this paper is to apply both time- and frequency-domain-based approaches on real-life civil engineering structures and to assess their capability for damage detection. The methodology is based ... [more ▼]

The aim of this paper is to apply both time- and frequency-domain-based approaches on real-life civil engineering structures and to assess their capability for damage detection. The methodology is based on Principal Component Analysis of the Hankel matrix built from output-only measurements and of Frequency Response Functions. Damage detection is performed using the concept of subspace angles between a current (possibly damaged state) and a reference (undamaged) state. The first structure is the Champangshiehl Bridge located in Luxembourg. Several damage levels were intentionally created by cutting a growing number of prestressed tendons and vibration data were acquired by the University of Luxembourg for each damaged state. The second example consists in reinforced and prestressed concrete panels. Successive damages were introduced in the panels by loading heavy weights and by cutting steel wires. The illustrations show different consequences in damage identification by the considered techniques. [less ▲]

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See detailValidation of a SPH model for free surface flows
Goffin, Louis ULg; Erpicum, Sébastien ULg; Dewals, Benjamin ULg et al

Conference (2014)

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See detailAlchemy and Art Technology in German Medieval and Early Modern Recipe Books
Neven, Sylvie ULg

in Dupré, Sven (Ed.) Laboratory of Art (2014)

In the Middle Ages and premodern period, artisanal knowledge was transmitted via collections of recipes often grouped concomitantly with alchemical texts and instructions. Except for some very well-known ... [more ▼]

In the Middle Ages and premodern period, artisanal knowledge was transmitted via collections of recipes often grouped concomitantly with alchemical texts and instructions. Except for some very well-known artistic treatises, such as those by Eraclius or the Schedula diversarum artium, attributed to Theophilus, detection and identification of alchemical content within recipe books has been rare and fraught with difficulty. In a broad sense, alchemy could be defined as the ‘art of transmutation’, referring to the perfection of base or impure matter (often metal or stone) into perfect substances. In this context, alchemical procedures rely on artisanal or craft practices. Thus, any overlap between alchemy and art-technological procedures can be explained by the use of various identical materials and substances. Both are concerned with the description of colours—especially in regard to processes of change, the making of pigments, the production of artificial gemstones, the imitation of gold and silver and the transmutation of materials. Both require procedures involving precise and specifically defined actions, prescriptions and ingredients. So both use identical rhetorical recipe formulations that reflect a ‘step by step’ procedure. Assuming that alchemical and artistic texts have the same textual format, raises the question: did they also have the same methods of production and reception? Using a corpus of about forty manuscripts produced in Northern Europe between the fourteenth and the sixteenth centuries, this paper investigates the authorship and the context of production behind these writings, and scrutinizes the process of their compilation and dissemination. This serves, on a variety of levels, to elucidate information about their former nature and use. Finally, this paper examines the various ways alchemical and artisanal recipes were embedded within recipe books. It also proposes some clues to help in locating, identifying and demarcating this type of alchemical writing within the literature of recipes. [less ▲]

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See detailL'entreprise comme mode de vie
Thirion, Nicolas ULg

in Autenne, Alexia; Strowel, Alain; Cassiers, Vincent (Eds.) Droit, économie, valeurs. Liber Amicorum Bernard Remiche (2014)

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See detailDes rapports entre le marché et la puissance publique: de l'Etat-Providence à l'Etat régulateur
Thirion, Nicolas ULg

in Thirion, Nicolas (Ed.) Crise et droit économique (2014)

L'étude vise à montrer le changement de philosophie sous-jacente au dispositif juridique applicable aux rapports entre le marché et l'Etat depuis la fin des Trente Glorieuses. De l'Etat-Providence, on ... [more ▼]

L'étude vise à montrer le changement de philosophie sous-jacente au dispositif juridique applicable aux rapports entre le marché et l'Etat depuis la fin des Trente Glorieuses. De l'Etat-Providence, on serait passé à l'Etat régulateur, davantage influencé par les écoles ordo-libérale et néo-libérale. [less ▲]

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See detailGeometric ferroelectricity in fluoroperovskites
Garcia-Castro, A. C.; Spaldin, Nicola A.; Romero, A. H. et al

in Physical Review B (2014), 89

We used first-principles calculations to investigate the existence and origin of the ferroelectric instability in the ABF3 fluoroperovskites. While the ground states of most ABF3 compounds are ... [more ▼]

We used first-principles calculations to investigate the existence and origin of the ferroelectric instability in the ABF3 fluoroperovskites. While the ground states of most ABF3 compounds are paraelectric (Pnma phase), we find that many fluoroperovskites have a ferroelectric instability in their high-symmetry cubic structure that is of similar amplitude to that commonly found in oxide perovskites. In contrast to the oxides, however, the fluorides have nominal Born effective charges, indicating a different mechanism for the instability.We show that the instability originates from ionic size effects, and is therefore in most cases largely insensitive to pressure and strain, again in contrast to the oxide perovskites. An exception is NaMnF3, where coherent epitaxial strain matching to a substrate with equal in-plane lattice constants destabilizes the bulk Pnma structure, leading to a ferroelectric, and indeed multiferroic, ground state with an unusual polarization/strain response. [less ▲]

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See detailShould I control or should I trust?
De Zanet, Fabrice ULg

Article for general public (2014)

Les employés sont censés agir dans l’intérêt de l’entreprise qui les emploient. Les stratégies pour s’en assurer vont du strict contrôle à la confiance absolue. Analyse.

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See detailValidation of differential drag propellantless maneuvers using 6 DoF simulations and stochastic dynamics
Dell'Elce, Lamberto ULg; Kerschen, Gaëtan ULg

in Proceedings of the 9th International ESA Conference on Guidance, Navigation & Control Systems (2014)

Differential drag is regarded as a promising technique in low-Earth orbits, since it allows to turn the often-undesired drag perturbation into a control force for relative maneuvers. Nonetheless, relevant ... [more ▼]

Differential drag is regarded as a promising technique in low-Earth orbits, since it allows to turn the often-undesired drag perturbation into a control force for relative maneuvers. Nonetheless, relevant uncertainties in drag modeling make its practical realization a challenge, especially if no other propulsive means is available to accommodate them. The main outcome of this study is the identification and characterization of the uncertainty sources affecting differential-drag-based maneuvers. This characterization is carried out by using statistical methods in conjunction with mechanical modeling considerations to infer a probabilistic model of the sources from observed data. The developments are illustrated in the framework of the QARMAN mission through high-fidelity simulations involving coupled attitude and orbital dynamics. [less ▲]

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See detailFirst-principles characterization of the P21ab ferroelectric phase of Aurivillius Bi2WO6
Djani-Ait, Hania ULg; Hermet, Patrick ULg; Ghosez, Philippe ULg

in Journal of Physical Chemistry C (2014), 118

The structural, dielectric, dynamical, elastic, piezoelectric and nonlinear optical (second-order susceptibility and Pockels tensors) properties of Bi2WO6 in its P21ab ferroelectric ground state are ... [more ▼]

The structural, dielectric, dynamical, elastic, piezoelectric and nonlinear optical (second-order susceptibility and Pockels tensors) properties of Bi2WO6 in its P21ab ferroelectric ground state are determined using density functional theory. The calculation of infrared and Raman spectra on single crystal allowed us to clarify the assignment of experimental phonon modes, considering the good agreement between the calculated and the experimental Raman spectra obtained on polycrystal. The calculation of the elastic constants con rms the elastic stability of the crystal and allow us to estimate the Young and shear moduli of polycrystalline samples. The piezoelectric constants have signi cant intrinsic values comparable to those of prototypical ABO3 ferroelectrics. The electro-optic response is strongly dominated by the ionic contribution of transverse optic modes, yielding sizable Pockels coe cients around 9 pm/V along the polar direction. [less ▲]

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See detailMicro-Computed Tomography Based Computational Fluid Dynamics for the Determination of Shear Stresses in Scaffolds Within a Perfusion Bioreactor
Zermatten, Emilie; Vetsch, Jolanda Rita; Ruffoni, Davide ULg et al

in Annals of Biomedical Engineering (2014), 42(5), 1085-1094

Perfusion bioreactors are known to exert shear stresses on cultured cells, leading to cell differentiation and enhanced extracellular matrix deposition on scaffolds. The influence of the scaffold's porous ... [more ▼]

Perfusion bioreactors are known to exert shear stresses on cultured cells, leading to cell differentiation and enhanced extracellular matrix deposition on scaffolds. The influence of the scaffold's porous microstructure is investigated for a polycaprolactone (PCL) scaffold with a regular microarchitecture and a silk fibroin (SF) scaffold with an irregular network of interconnected pores. Their complex 3D geometries are imaged by micro-computed tomography and used in direct pore-level simulations of the entire scaffold-bioreactor system to numerically solve the governing mass and momentum conservation equations for fluid flow through porous media. The velocity field and wall shear stress distribution are determined for both scaffolds. The PCL scaffold exhibited an asymmetric distribution with peak and plateau, while the SF scaffold exhibited a homogenous distribution and conditioned the flow more efficiently than the PCL scaffold. The methodology guides the design and optimization of the scaffold geometry. [less ▲]

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See detailEscherichia coli in domestic mammals and birds.
Mainil, Jacques ULg; Fairbrother, John

in Morabito, Stefano (Ed.) Pathogenic Escherichia coli : Molecular and cellular microbiology (2014)

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See detaileLearning COLEACP : un dispositif de formation au service des professionnels du secteur agricole en Afrique
Prunier, Emmanuelle; Le Hung, Florian; Schiffers, Bruno ULg

in ELearning Africa 2014 - Book of Abstracts (2014)

Le dispositif de formation à distance du COLEACP (Comité de Liaison Europe-Afrique-Caraïbes-Pacifique) est une composante d'un système complet de formation dédié au renforcement des capacités des ... [more ▼]

Le dispositif de formation à distance du COLEACP (Comité de Liaison Europe-Afrique-Caraïbes-Pacifique) est une composante d'un système complet de formation dédié au renforcement des capacités des opérateurs des filières agricoles des pays ACP (Afrique Caraïbes et Pacifique). [less ▲]

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See detailDurability of hydrophobic treatments on concrete monuments
Courard, Luc ULg; Lucquiaud, Vincent ULg; Gérard, Olivier et al

in Proceedings of 7th International Conference on Water Repellent Treatment and Protective Surface Technology for Building Materials (2014)

The protection of concrete historical structures is a challenge for the coming years. Hydrophobic treatment may induce a delay in degradations progress as well as a protection against water penetration ... [more ▼]

The protection of concrete historical structures is a challenge for the coming years. Hydrophobic treatment may induce a delay in degradations progress as well as a protection against water penetration. Existing products - mainly silane and siloxane based – have been submitted to different ageing processes including UV radiation, moistening cycles, thermal shocks, freeze-thaw cycles, carbonation and efficiency has been evaluated on the base of contact angle, vapour and chloride permeability and, capillarity absorption. Investigation results clearly show a good behaviour of hydrophobic treatments under main ageing conditions. [less ▲]

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See detailLight modulation of human sleep depends on a polymorphism in the clock gene Period3.
Chellappa, Sarah Laxhmi ULg; Viola, Antoine U.; Schmidt, Christina ULg et al

in Behavioural brain research (2014), 271

Non-image-forming (NIF) responses to light powerfully modulate human physiology. However, it remains scarcely understood how NIF responses to light modulate human sleep and its EEG hallmarks, and if there ... [more ▼]

Non-image-forming (NIF) responses to light powerfully modulate human physiology. However, it remains scarcely understood how NIF responses to light modulate human sleep and its EEG hallmarks, and if there are differences across individuals. Here we investigated NIF responses to light on sleep in individuals genotyped for the PERIOD3 (PER3) variable-number tandem-repeat (VNTR) polymorphism. Eighteen healthy young men (20-28 years; mean+/-SEM: 25.9+/-1.2) homozygous for the PER3 polymorphism were matched by age, body-mass index, and ethnicity. The study protocol comprised a balanced cross-over design during the winter, during which participants were exposed to either light of 40lx at 6500K (blue-enriched) or light at 2500K (non-blue enriched), during 2h in the evening. Compared to light at 2500K, light at 6500K induced a significant increase in all-night NREM sleep slow-wave activity (SWA: 1.0-4.5Hz) in the occipital cortex for PER3(5/5) individuals, but not for PER3(4/4) volunteers. Dynamics of SWA across sleep cycles revealed increased occipital NREM sleep SWA for virtuallyall sleep episode only for PER3(5/5) individuals. Furthermore, they experienced light at 6500K as significantly brighter. Intriguingly, this subjective perception of brightness significantly predicted their increased occipital SWA throughout the sleep episode. Our data indicate that humans homozygous for the PER3(5/5) allele are more sensitive to NIF light effects, as indexed by specific changes in sleep EEG activity. Ultimately, individual differences in NIF light responses on sleep may depend on a clock gene polymorphism involved in sleep-wake regulation. [less ▲]

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See detailKeping Tabs on Dioxins
Focant, Jean-François ULg

in The Analytical Scientist (2014), 15

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See detailChemical and biological evaluation of the nutritive value of Algerian green seaweed Ulva lactuca using in vitro gas production technique fior ruminant animals
Zitouni, Hind; Arhab, Rabah; Boudry, Christelle ULg et al

in International Journal of Advanced Research (2014), 2(4), 916-925

This study aimed to determine the nutritive value of seaweed Ulva lactuca collected from the Algerian coast by estimation of its chemical composition and fermentation characteristics, comparatively to ... [more ▼]

This study aimed to determine the nutritive value of seaweed Ulva lactuca collected from the Algerian coast by estimation of its chemical composition and fermentation characteristics, comparatively to vetch-oat hay (control), using in vitro gas production technique. Seaweed and control were incubated with rumen liquor taken from fistulated and non lactating cows. Gas production was recorded at: 2, 4, 6, 8, 12, 24, 48 and 72h. The in vitro rumen fermentation parameters were measured after 24h and 72h of fermentation. Proteins degradability was investigated by the enzymatic technique using a protease extracted from Streptomyces griseus. The results showed a wide variation between the chemical components of seaweed and conventional fodder used as control. The main constituents in Ulva lactuca were ashes (39.1% DM), fibers (22.8 % DM) and proteins (15.3% DM). The gas production profile of seaweed during 72h of incubation showed a slow and low gas production. Cumulative gas production obtained after 24h for seaweed (42 ml/g OM) was significantly lower than control (128.4 ml/g OM) (P<0.001). pH, ammonia, volatile fatty acids (VFAs), apparent digestibility of dry matter (DDM), organic matter digestibility (OMD) and metabolizable energy (ME) were significantly different between seaweed and vetch-oat hay (6.86, 290.1 mg/ml, 1.25 mmol/g DM, 38.3%, 29.2%, 3.81MJ/Kg DM respectively for seaweed). Protein degradability measurement indicates the weak hydrolysis of seaweed crude protein which is beneficial for ruminants. This study showed that the use of Ulva lactuca as non conventional feed in ruminant nutrition can be considered under certain conditions. [less ▲]

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