Sur des approches logicielles avancées pour le traitement de multiphysiques couplées en mécanique

Les couplages multiphysiques, en particulier dans les matériaux poreux, couvrent de nos jours de plus en plus de domaines d'application. Ces problématiques font en général intervenir de nombreux champs couvrant plusieurs physiques à des échelles de temps et d'espace très différentes. Un des enjeux cruciaux des aspects liés à la modélisation est de facilement et rapidement intégrer les nouveaux modèles dans des logiciels de simulation, afin d'une part de valider les approches, et d'autre part, de proposer en un temps raisonnable des solutions logicielles prédictives adaptées au milieu industriel. Le but de cette communication est de mettre en perspective deux approches de développement logiciel dans le cadre de la modélisation de systèmes multiphysiques complexes, l'une classique et l'autre avancée en orientée objet

Compensating for Electrode Polarization in Dielectric Spectroscopy Studies of Colloidal Suspensions: Theoretical Assessment of Existing Methods

International audienceDielectric spectroscopy can be used to determine the dipole moment of colloidal particles from which important interfacial electrokinetic properties, for instance their zeta potential, can be deduced. Unfortunately, dielectric spectroscopy measurements are hampered by electrode polarization (EP). In this article, we review several procedures to compensate for this effect. First EP in electrolyte solutions is described: the complex conductivity is derived as function of frequency, for two cell geometries (planar and cylindrical) with blocking electrodes. The corresponding equivalent circuit for the electrolyte solution is given for each geometry. This equivalent circuit model is extended to suspensions. The complex conductivity of a suspension, in the presence of EP, is then calculated from the impedance. Different methods for compensating for EP are critically assessed, with the help of the theoretical findings. Their limit of validity is given in terms of characteristic frequencies. We can identify with one of these frequencies the frequency range within which data uncorrected for EP may be used to assess the dipole moment of colloidal particles. In order to extract this dipole moment from the measured data, two methods are reviewed: one is based on the use of existing models for the complex conductivity of suspensions, the other is the logarithmic derivative method. An extension to multiple relaxations of the logarithmic derivative method is proposed

Compensating for electrode polarization in dielectric spectroscopy studies of colloidal suspensions: Theoretical assessment of existing methods

Dielectric spectroscopy can be used to determine the dipole moment of colloidal particles from which important interfacial electrokinetic properties, for instance their zeta potential, can be deduced. Unfortunately, dielectric spectroscopy measurements are hampered by electrode polarization (EP). In this article, we review several procedures to compensate for this effect. First EP in electrolyte solutions is described: the complex conductivity is derived as function of frequency, for two cell geometries (planar and cylindrical) with blocking electrodes. The corresponding equivalent circuit for the electrolyte solution is given for each geometry. This equivalent circuit model is extended to suspensions. The complex conductivity of a suspension, in the presence of EP, is then calculated from the impedance. Different methods for compensating for EP are critically assessed, with the help of the theoretical findings. Their limit of validity is given in terms of characteristic frequencies. We can identify with one of these frequencies the frequency range within which data uncorrected for EP may be used to assess the dipole moment of colloidal particles. In order to extract this dipole moment from the measured data, two methods are reviewed: one is based on the use of existing models for the complex conductivity of suspensions, the other is the logarithmic derivative method. An extension to multiple relaxations of the logarithmic derivative method is proposed.Environmental Fluid MechanicsChemE/Algemee

La draperie en Normandie du XIIIe siècle au XXe siècle

Né des rencontres suscitées par les euroconférences de 2001 et 2002 consacrées à l'histoire de la laine, cet ouvrage réunit une quinzaine de contributions de chercheurs normands mais aussi parisiens et étrangers. De l'époque médiévale à la particularisation actuelle, en passant par l'apogée des xviiie et xixe siècles, les auteurs analysent la production des différents centres normands, les réseaux de commercialisation et d'exportation, les mécanismes des transferts de technologie. Se recoupant et se répondant les unes aux autres, ces études éclairent l'histoire de l'une des principales activités industrielles de la région

Composite and sequential lymphoma between classical Hodgkin lymphoma and primary mediastinal lymphoma/diffuse large B‐cell lymphoma, a clinico‐pathological series of 25 cases

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