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This article proposes a multiphysics multimethod model for 3-D nonlinear magnetoelectric (ME) effects in heterogeneous composite structures made of the association of piezoelectric and magnetostrictive materials. Through the coupling of the finite element method (FEM) with the boundary element method (BEM), only the active material is explicitly considered, and thus a single mesh is used for the resolution of all the physics. A mixed formulation combining the vector potential in the volume and a scalar potential in the free space is used to model magnetic phenomena. Nonlinear constitutive laws for the magnetostrictive phase are derived from partial derivatives of a scalar invariant’s formulation of the Helmholtz free energy, while linear relations are used to describe piezoelectric behavior. The coupled problem is solved by iteratively solving single-physics problems, and the full algorithm is used to model a rotating coilless ME device which can operate as an energy harvester or as an actuator.

Cet article présente une nouvelle cellule réactive dédiée à l'étude in-situ par spectroscopie d'absorption X de catalyseurs de dépollution pour moteurs Diesel. Cet appareillage a été développé pour collecter des spectres EXAFS pendant la réaction chimique, l'échantillon étant placé sous un flux gazeux constitué des principaux gaz réactifs constitutifs des échappements de moteurs Diesel. Une attention particulière a été portée sur la forme et le matériau du porte-échantillon. En effet, une géométrie spéciale a été élaborée pour étudier le catalyseur directement dans sa forme finale, c'est-à-dire tel qu'il est dans le pot d'échappement en tenant compte des conditions réactionnelles (température et vitesse volumique horaire élevée).

Face aux difficultés pour trouver un catalyseur efficace dans la réaction de réduction de NO par les hydrocarbures en milieu oxydant dans le cadre du traitement post-combustion des moteurs Diesel, nous avons étudié l'interaction de certains des gaz concernés (NO, C3H6et O2) avec un catalyseur constitué de particules de platine à l'échelle nanométrique déposé sur un support alumine. Il est important en effet de comprendre le processus catalytique associé à cette réaction de réduction, notamment l'évolution structurale et électronique des particules pendant l'acte catalytique. Nous avons ainsi pu mettre en évidence que la présence de NO seul entraînait une augmentation importante de la taille moyenne des particules. D'autre part, l'influence de NO ou de C3H6en présence d'un excès d'oxygène est sensible au niveau de l'oxydation totale des particules : celle-ci est en effet moins importante. En présence d'un mélange complet regroupant ces trois gaz, il s'avère que les particules s'agrègent et s'oxydent.

L'analyse des dispositifs électrotechniques est souvent limitée par les sources d'alimentation. En effet, dans le cas de conducteurs massifs, la valeur de la tension est requise, alors que, dans le cas de conducteurs bobinés, le courant doit être connu. Ces restrictions sont dues à la nature des équations de champ. Une nouvelle formulation est proposée qui permet de choisir la source d'alimentation et d'autoriser tous les types de connexions entre les composants. Deux types de “conducteurs magnétiques” sont considérés : les conducteurs massifs, dans lesquels des courants de Foucault peuvent être induits et les conducteurs bobinés sans courants de Foucault. Une équation associant le potentiel vecteur magnétique, le courant et la tension est établie pour chaque type de conducteurs. Cette équation est introduite dans une méthode conventionnelle d'analyse des circuits électriques. Les équations électriques et magnétiques sont résolues simultanément. Une méthode implicite est utilisée pour discrétiser les équations dans le temps. Un algorithme de linéarisation de Newton-Raphson est utilisé pour les problèmes qui incluent des matériaux à caractéristiques non linéaires. Cette formulation a été implantée dans un logiciel commercial FLUX2D. Pour illustrer une des nombreuses applications, un contacteur électromagnétique avec spires de Frager est modélisé.

Dans cet article, nous présentons le calcul des paramètres inductifs et capacitifs d'un transformateur de puissance à l'aide de méthodes numériques utilisant les éléments finis en trois dimensions. La modélisation, basée sur un calcul par éléments finis du champ électromagnétique, permet d'aborder sous un nouvel angle l'étude des phénomènes haute fréquence se propageant dans les enroulements d'un transformateur. La méthode est appliquée à un transformateur de puissance de type cuirassé à l'aide du logiciel FLUX3D.

l'absorption X est une technique puissante pour l'étude de catalyseurs trois voies à très faibles teneurs en metaux précieux (Pt, Rh). Il a été montré l'existence de distances interatomiques dPtOet dRhOcontractées par comparaison aux oxydes massiques PtO2et Rh2O3attribuées à un effet de taille de particule à température inférieure à 800 °C, alors qu'à 1600°C les distances dPtO, dRhOsont anormalement grandes dues à une très forte interaction des métaux avec le support Al2O3. La mise en évidence de phases alliages, à T > 800 °C conforte nos résultats antérieurs. L'allure des transformées de Fourier (T.F.) est alors très particulière, confirmée par une modélisation des modules de la T.F. pour Pt xRh1-x(0

Highly magnetostrictive materials such as Tb-3Dy7Fe2, commercially known as Terfenol-D, have been used to date in a variety of devices such as high power actuators and linear motors. The authors are investigating a finite element model devoted to Computer Aided Design (CAD) of a direct micro-stepping rotary motor. Such a motor would be a high torque micro-radian stepper, capable of precision movements and self-braking in the power off state. The thrust of this paper is to test the validity of the so-called "weak coupling" approach on a motor based on the proven inch worm technique. Comparison between numerical outputs from the model and test results on prototype hardware will be presented.

Light scattering methods are often used to study the stability of suspensions or emulsions and to estimate the dispersed phase properties such as particle size and volume fraction. However, such optical methods often require a previous dilution of the dispersion because of a limited measurement range, and are then unable to give information about the real physical state of dense heterogeneous media. A new technology based on multiple light scattering analysis and called Turbiscan has been recently developed by a French company, Formulaction, to fill this gap and to characterize both diluted and concentrated dispersions. In the first part, we review the physical concepts of multiple light scattering by dispersions. In relation to the optical analyser Turbiscan, we present physical and statistical models for the radiative transfer in dense suspensions. In the second part, we investigate the influence of particle volume fraction and particle size (polystyrene latex bead suspensions) on the backscattered and transmitted light fluxes measured by Turbiscan. The experimental data are compared with results from the physical models. In the last section, we use the optical analyser Turbiscan Lab to detect and characterize various concentrated dispersions destabilization (coalescence, flocculation, creaming and sedimentation), and then the Turbiscan On Line to monitor and characterize an emulsification process under ultrasonic agitation. Copyright © 2004 Society of Chemical Industry

Most new ships are electrically driven. However, some military or oceanographic ships require low magnetic stray fields. Thus, electrical machines for propulsion have to be magnetically silent. The calculation of magnetic stray fields far from an electromagnetic device by standard finite-element method (Flux3d) may be inaccurate. Numerical noise may appear that can be as high as the weak magnetic induction to be computed. Consequently the calculation of low fields requires a specific model. A model has been developed in the Flux3d post processing. The principle is to use the magnetisation of the ferromagnetic parts of the device. The magnetisation is well computed by Flux3d (high field values). This magnetisation allows one to analytically calculate the induction outside the device by using the magnetic moment equivalence. Finally, the magnetic noise is eradicated and the model is able to calculate low field values. To validate our model, a comparison with measurements on a synchronous permanent magnet machine has been made. Experiments give good results and the validation is satisfactory. The effects of each magnetic source (rotor magnets and stator coils) of the machine are well calculated. The model is mainly static. Its application to the computation of the stray fields while the motor is rotating is presented.

Meshless methods are new numerical simulation methods. Meshless methods are based on a simple set of nodes that has to be optimized to obtain a good convergence of the approximation. For these reasons, in this paper, we have developed a new procedure in order to generate the initial set of nodes. This approach does not rely on any existing meshing technique, such as Delaunay or advancing front. It is based on a map density of nodes and a regularization procedure.

Meshless methods are new numerical simulation methods. Meshless methods are based on a simple set of nodes that has to be optimized to obtain a good convergence of the approximation. For these reasons, in this paper, we have developed a new procedure in order to generate the initial set of nodes. This approach does not rely on any existing meshing technique, such as Delaunay or advancing front. It is based on a map density of nodes and a regularization procedure.

The 3D modeling of thin structures by the finite element method leads to a high number of elements or elements of bad quality, which yields to badly conditioned problems. For the thin plates, shell formulations have been used by several authors. In the case of thin wires, we use a model of unmeshed conductor in which the current is unknown. Physics characteristics: resistance, inductance are integrated in the circuit equation. This article presents a method that extracts the inductance computation which introduced a singularity in the case of thin wires.

The 3D modeling of thin structures by the finite element method leads to a high number of elements or elements of bad quality, which yields to badly conditioned problems. For the thin plates, shell formulations have been used by several authors. In the case of thin wires, we use a model of unmeshed conductor in which the current is unknown. Physics characteristics: resistance, inductance are integrated in the circuit equation. This article presents a method that extracts the inductance computation which introduced a singularity in the case of thin wires.

Face to the difficulty to find an efficient catalyst in the reduction of NO by hydrocarbon in diesel exhaust gases, we have examined the interaction of some concerned reactant gases, NO, C3H6and O2, with a catalyst constituted of nanometer scale platinum particles deposited on alumina. Indeed, in order to understand the catalytic process, it seems essential to have information on the adsorption process and on the evolution of the structural parameters of the particles when submitted to such gases. This work has been performed on a 1% Pt/Al2O3catalyst by using in situ EXAFS measurements. We have concentrated our study, on the one hand, on the influence of NO, C3H6in the presence or not of an excess of oxygen and, on the other hand, on the influence of the total mixture. The most striking result is the growth of the platinum particles under NO. Moreover, when the catalyst is submitted either to a mixture of NO + O2or C3H6+ O2, the particles are not fully oxidised. With the total mixture, the particles both grow and are oxidised.

When performing the analysis of electromechanical transient problems with movement, it is needed to take into account the air gap deformation with time. A new remeshing procedure is proposed. It is based on node displacements coupled to a Delaunay algorithm. The node movement is described using bubbles in association with a physical model. The procedure generates high-quality meshes.

When performing the analysis of electromechanical transient problems with movement, it is needed to take into account the air gap deformation with time. A new remeshing procedure is proposed. It is based on node displacements coupled to a Delaunay algorithm. The node movement is described using bubbles in association with a physical model. The procedure generates high-quality meshes.

Residual endotoxins, commonly associated with bacterial biofilms colonizing reusable medical devices have been associated with pyrogenic reactions in patients. We have used a quantitative, sensitive and reproducible kinetic chromogenic adaptation of the Limulus Amebocyte Lysate assay to assess endotoxin recovery from an in-vitro bacterial biofilm. The ‘recovery method’ was based on a combination of physical treatment (vortexing and sonication) and chemical treatment (immersion in recovery solution). Five recovery solutions were investigated. The recovered endotoxin was greater when the biofilm was treated with a 1% SDS solution. The sensitive and reproducible method we have developed should allow the recovery and measurement of biofilm bacterial endotoxins on implanted and colonized medical devices. Moreover, the amount of endotoxin was sufficient (> 1000 endotoxin units/cm2of substrate) to enable a substantial reduction by sterilization processes, the efficiency of which on biofilm endotoxins has yet to be proven.

The precision of the classical equivalent circuit of a transformer is not sufficient for the software simulation of a high frequency power supply to be true. In this paper we show that, by adding some components to the classical circuit, eddy currents in windings can be taken into account. First, this modification was deduced from experimental results. Then, thanks to an homogeneous layer model, an analytical study was carried out. This enabled the above circuit to be justified and expressions to be derived for the supplementary components values. Finally, a more exact geometry was investigated thanks to an electromagnetic software simulation. The corresponding results agree well with analytical and experimental ones.

Notre recherche consiste à concevoir et réaliser une source de flux statique à aimants permanents générant un champ de 4 à 5 Tesla dans un volume de quelques mm3. Un des aspects novateurs de cette approche est que nous avons cherché à obtenir un champ magnétique intense (principe du dipôle ponctuel) et non pas un champ magnétique homogène (principe du dipôle infini utilisé dans les structures de Leupold/Halbach). Après optimisation du modèle analytique, nous avons discrétisé la structure de manière à obtenir un modèle réalisable à partir de pavé d'aimants réels. Une originalité du travail est la recherche d'une géométrie performante et une combinaison de divers matériaux magnétiques durs (nuances d'aimants Néodyme-Fer-Bore) et de matériau magnétique doux (Fer-Cobalt). Les configurations particulières d'aimants sont optimisées par simulation numérique grâce à des logiciels complémentaires, développés par le LEG : DIPOLE-3D (calcul analytique de champ), FLUX2D et FLUX3D (éléments finis). L'étude de faisabilité du projet a été réalisée en calculant les forces et les champs démagnétisants lors de la séquence de montage. Le modèle de source actuel fournit un champ atteignant 4,3 T dans un volume de diamètre de 6 mm pour une hauteur de 2,8 mm et ayant un diamètre extérieur de 100 mm.

The transformation of the antitumor drug N2-methyl-9-hydroxy-ellipticinium by a peroxidase-hydrogen peroxide system, which has been shown to occur in vivo, leads to an electrophilic quinone-imine derivative. This unstable molecule arylates in vitro purine nucleosides and nucleotides, leading to regioselective adducts substituted only at the 2'-O position of the ribose, as shown by mass spectrometry and NMR. It is likely that an important preliminary step in this reaction is a stacking process between the ellipticinium ion and the purine rings, which might explain this regioselectivity.

In this study, new amorphous molybdenum oxysulfide thin films, prepared by r.f. magnetron sputtering and which could be used as positive electrode materials in microbatteries, were analyzed by X-ray photoelectron spectroscopy. In light of the binding energies obtained for reference compounds (different molybdenum oxides and sulfides), the results have shown the existence of several environments of molybdenum atoms. In addition to environments such as in MoO3and MoS2, a new one has been identified; the closest neighbors of this molybdenum appear to be isolated “S2−”, disulfide “(S2)2−” ions, and “O2−” ions with the sulfur ions present in the same proportions as the oxygen ions.

Despite numerous reports on the N-demethylation reactions catalyzed by peroxidases, to our knowledge, O-demethylation reactions with the same enzymes seem to be still a questionable matter. Unexpectedly, a peroxidase system (horseradish peroxidase and hydrogen peroxide) is able to effect the O-demethylation of the cytotoxic agents 9-methoxyellipticine and N2-methyl-9-methoxyellipticinium acetate. The reaction leads directly to the formation of the corresponding quinone-imine derivatives with the concomitant formation of one molecule of methanol per molecule of methoxy compound. One hydrogen peroxide molecule is consumed during the process. Experiments in H218O-enriched water clearly indicate that 18O is nearly quantitatively incorporated in the carbonyl group of the generated quinone-imine compound with the concomitant elimination of the methoxy group as methanol. So this peroxidase-catalyzed apparent O-demethylation in fact implies an oxidative demethoxylation step. This enzymatic reaction exhibits normal Michaelis-Menten saturation kinetics. Like the 9-hydroxylated ellipticines, both the 9-methoxylated ellipticines show a good affinity for the peroxidase itself (Km approximately 10 microM) but are slowly transformed to the corresponding quinone-imines. The Vmax values for methoxylated ellipticines are 10(-1)-10(-3) lower than those for hydroxylated compounds. This new route for the in vitro formation of electrophilic derivatives from the cytotoxic 9-methoxyellipticine and N2-methyl-9-methoxyellipticinium might be considered as a novel possible metabolic pathway for these drugs, especially if we bear in mind the “bio-oxidative alkylation” process previously described for at least one of the corresponding hydroxylated ellipticine derivatives (see Bernadou, J., Meunier, B., Meunier, G., Auclair, C., and Paoletti, C. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 1297-1301; and Monsarrat, B., Maftouh, M., Meunier, G., Dugué, B., Bernadou, J., Armand, J. P., Picard-Fraire, C., Meunier, B., and Paoletti, C. (1983) Biochem. Pharmacol. 32, 3887-3890).

Most electromagnetic field computation programs are generally able to take into account the characteristics of magnetic materials of two kinds: (1) materials with linear characteristics which may be isotropic and possibly with residual magnetization. (2) soft isotropic nonlinear materials. The implementation of these models in a finite element package allows us to compute the magnetic field in a large number of electric devices. However, many devices are in reality made of materials with more complex characteristics. Especially those exhibiting anisotropic nonlinear phenomena, as in grain-oriented laminations, cannot be analyzed using presently available models. This paper presents two models of this kind of material in the frame of a magnetostatic analysis. They can be used for the computation of magnetic fields in configurations involving nonlinear permanent magnets and grain-oriented laminations. Furthermore we present a survey of the finite element formulations for this kind of problem with special attention to the methodology of implementation. Finally, some examples of the applications of the models are presented. These examples verify the proposed models by replicating on the computer the results of a practical experiment and demonstrate our new ability to model and predict complex magnetic phenomena.

Cet article présente le problème de la modélisation en trois dimensions des boucles d'immunisation des navires par la méthode des éléments finis. Nous montrons que ces boucles de courant sont si proches des tôles ferromagnétiques du navire que leur modélisation requiert un maillage localement très fin, ce qui est irréaliste pour la structure complexe d'un navire réel. Nous proposons une alternative à ce coûteux affinage du maillage, appelée "saut de potentiel réduit". L'idée est de résoudre au préalable le problème local par une autre méthode que les éléments finis et d'utiliser le résultat dans la modélisation globale. Nous présentons la méthode utilisée pour l'implantation de cette technique dans le logiciel d'éléments finis FLUX3D, et des résultats comparatifs sur une géométrie simple.

In the family of ellipticine derivatives, those with an amino-phenol or a masked amino-phenol structure are among the most cytotoxic compounds. Preliminary studies on 9-hydroxy- or 9-methoxyellipticines have shown that these molecules behave as "pro-alkylating" agents. In order to rationalize the "biooxidative alkylation" process for various ellipticine derivatives, we report in the present article (i) their electrochemical oxidation parameters, (ii) their biochemical oxidation, (iii) the ability of the oxidized forms to form adducts with nucleophiles, (iv) the biological activities, and (v) the electronic properties of oxidized forms. We present some possible correlations between the oxidizability, the electrophilicity of the oxidized derivatives, and the biological activities of the corresponding drugs.

So as to compute the electric potential and the flux density generated by the electrical activity of the brain, numerical methods based on the Finite Element Method have been developed. These methods, which can treat realistic head models and can take into account anisotropy of conductivity, for instance in the skull, are presented. Then two numerical examples are described: a spherical model and a realistic head model. Afin de calculer le potentiel ?lectrique et l'induction cr??s par l'activit? ?lectrique du cerveau, nous avons d?velopp? des m?thodes utilisant la M?thode des ?l?ments Finis. Ces m?thodes, qui peuvent s'appliquer ? des mod?les r?alistes de t?te et qui permettent de tenir compte de la conductivit? anisotrope de certains tissus comme l'os, sont pr?sent?es. Puis deux exemples num?riques sont d?crits : un mod?le de sph?res concentriques et un mod?le r?aliste de t?te.

In this paper, we present the inductive and capacitive parameters computation of a power transformer with numerical methods using the finite elements in three dimensions. The modeling, based on the computation of the 3D electromagnetic field allows for a new approach to the study of the high frequency phenomena that propagates along the transformer windings. The method is applied to a power shell form transformer using the 3D package FLUX3D. Dans cet article, nous pr?sentons le calcul des param?tres inductifs et capacitifs d'un transformateur de puissance ? l'aide de m?thodes num?riques utilisant les ?l?ments finis en trois dimensions. La mod?lisation, bas?e sur un calcul par ?l?ments finis du champ ?lectromagn?tique, permet d'aborder sous un nouvel angle l'?tude des ph?nom?nes haute fr?quence se propageant dans les enroulements d'un transformateur. La m?thode est appliqu?e ? un transformateur de puissance de type cuirass? ? l'aide du logiciel FLUX3D.

This paper deals with 3D electromagnetic modelling of a transformer so as to evaluate eddy current losses in the tank. In this purpose, several numerical methods have been used with two 3D softwares, FLUX3D (LEG) and TRIFOU (EDF). These methods use either nodal finite elements with the magnetic vector potential (FLUX3D), or the edge finite elements with the magnetic field as the state variable (TRIFOU). Classical volume elements and several special elements have been used : shell elements with the magnetic vector potential for the modelling of thin conducting regions, and surface elements for conducting regions with a small skin depth. The results given by these methods with several characteristics of the tank and magnetic core have been compared and their validity domain has been verified. The shell elements suit well when the skin depth is larger than the tank thickness, whereas in the opposite case, the surface elements for thin skin depth regions are well adapted. Nous pr?sentons la mod?lisation tridimensionnelle d'un transformateur pour la d?termination des pertes par courants de Foucault dans sa cuve. Pour cela, plusieurs m?thodes num?riques ont ?t? utilis?es ? l'aide de deux codes de calcul tridimensionnels : FLUX3D (LEG) et TRIFOU (EDF). Ces m?thodes utilisent soit les ?l?ments finis nodaux avec le potentiel vecteur magn?tique (FLUX3D), soit les ?l?ments finis d'ar?te avec le champ magn?tique comme variable d'?tat (TRIFOU). Outre l'utilisation des ?l?ments volumiques, nous avons employ? des ?l?ments surfaciques de type coque en potentiel vecteur magn?tique pour la mod?lisation de regions conductrices minces, ainsi que des ?l?ments surfaciques pour les r?gions conductrices pr?sentant une faible ?paisseur de peau. Les r?sultats obtenus avec ces m?thodes pour diff?rentes caract?ristiques du mat?riau de la cuve et du circuit magn?tique ont permis de v?rifier leur domaine de validit?. Les ?l?ments de type coque conviennent lorsque l'?paisseur de peau est largement plus grande que l'?paisseur de la cuve, alors que dans le cas contraire, ce sont les ?l?ments surfaciques pour les r?gions ? faible profondeur de p?n?tration qui sont le mieux adapt?s.

The paper presents the open boundary modelling method using transformation. This method may be summarized by the use of mappings which link the real open domain with an image closed domain. This image domain is then meshed by classical finite element. The best method to take the transformation into account is to consider that the elements of the image domain allow to define finite elements and shape functions on the real domain. This new set of finite elements, called the mapped infinite elements, are able to simulate infinite domain. The paper also presents results obtained using this method. They show the value of the method as well as its limits. L'article pr?sente la m?thode de mod?lisation ?l?ments finis de l'infini ? l'aide de transformations. Cette m?thode peut se r?sumer par l'utilisation de transformations reliant le domaine ouvert ? un domaine ferm? image, qui est alors maill? en ?l?ments finis classiques. L'application locale de la transformation sur les ?l?ments du domaine image permet de d?finir de nouveaux ?l?ments. Ces nouveaux ?l?ments, appel?s ?l?ments finis transform?s, peuvent s'?tendre jusqu'? l'infini et sont donc capables de prendre en compte les domaines ? fronti?res ouvertes. L'article pr?sente aussi les demiers r?sultats obtenus ? l'aide de cette m?thode. Les grandeurs calcul?es aux moments de l'exploitation sont les grandeurs les plus difficiles qu'ils soient, puisqu'il s'agit de grandeurs locales (champ-potentiel) dans le domaine ext?rieur ? ?tant entendu que les autres grandeurs (grandeurs globales comme les forces ou l'?nergie, ou grandeurs locales dans le domaine int?rieur) sont bonnes. Ces r?sultats montrent la valeur (ce qui signifie aussi les limites) de la m?thode propos?e.

The non-linear analysis of electrical devices is often limited by the complexity of the power supply. In effect, in the case of solid conductors, the voltage is required, while in the case of stranded conductors, the current must be known. These restrictions are due to the nature of the field equations. A new formulation is proposed which allows the possibility to choose the power supply and choose any kind of connection between components. Two types of ?magnetic conductors? are considered: solid conductors, in which eddy current can be induced and stranded conductors without eddy current. An equation combining the magnetic potential, the current and the voltage is established for each conductor. This equation is introduced into a conventional circuit analysis method. The magnetic field and circuit equations can be solved simultaneously in the resulting system. An implicit method is used to discretize the equation in time. A NewtonRaphson linearization algorithm is used to handle problems that include materials with non linear properties. This formulation is used in the commercial program FLUX2D. To illustrate one of the many applications, an A.C. electromagnet is studied. L'analyse des dispositifs ?lectrotechniques est souvent limit?e par les sources d'alimentation. En effet, dans le cas de conducteurs massifs, la valeur de la tension est requise, alors que, dans le cas de conducteurs bobin?s, le courant doit ?tre connu. Ces restrictions sont dues ? la nature des ?quations de champ. Une nouvelle formulation est propos?e qui permet de choisir la source d'alimentation et d'autoriser tous les types de connexions entre les composants. Deux types de ?conducteurs magn?tiques? sont consid?r?s : les conducteurs massifs, dans lesquels des courants de Foucault peuvent ?tre induits et les conducteurs bobin?s sans courants de Foucault. Une ?quation associant le potentiel vecteur magn?tique, le courant et la tension est ?tablie pour chaque type de conducteurs. Cette ?quation est introduite dans une m?thode conventionnelle d'analyse des circuits ?lectriques. Les ?quations ?lectriques et magn?tiques sont r?solues simultan?ment. Une m?thode implicite est utilis?e pour discr?tiser les ?quations dans le temps. Un algorithme de lin?arisation de Newton-Raphson est utilis? pour les probl?mes qui incluent des mat?riaux ? caract?ristiques non lin?aires. Cette formulation a ?t? implant?e dans un logiciel commercial FLUX2D. Pour illustrer une des nombreuses applications, un contacteur ?lectromagn?tique avec spires de Frager est mod?lis?.

In order to reach a significant comparison between measured and computed curves, we carry out a VSM hysteresis measurement and a simulation for the experimental device which measures the hysteresis loops. The aim of our paper is to present the details of such a simulation, using 2D-finite element analysis combined with a model based on a gaussian assembly of uniaxial anisotropy particles. The intrinsic hysteresis characteristics are computed and compared to the measured ones.

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