WorldCat Identities

Laboratoire AMPERE (Ecully, Rhône)

Overview
Works: 82 works in 107 publications in 2 languages and 110 library holdings
Roles: Other, 981
Publication Timeline
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Most widely held works by Rhône) Laboratoire AMPERE (Ecully
Etude des caractéristiques statiques des structures thyristor commandées par grille isolée : le thymos by Eric Baudelot( Book )

1 edition published in 1983 in French and held by 3 WorldCat member libraries worldwide

Cette étude porte sur le comportement statique, par opposition à la commutation, d'un nouveau composant de puissance, constitué de quatre couches de types alternés, comme un thyristor, mais commandé par une grille isolée du type MOS, que nous nommons THYMOS. Ses caractéristiques électriques sont analysées. Les différents modes de fonctionnement sont interprétés et leurs avantages et inconvénients respectifs sont présentés et comparés avec ceux des transistors DMOS de puissance. Enfin, les paramètres physiques et géométriques permettant l'optimalisation du mode de fonctionnement le plus intéressant sont déduits d'une modélisation du dispositif et de nouveaux axes de travail pour développer le THYMOS sont proposés
Modélisation par approche quadripolaire des courants de mode commun dans les associations convertisseurs-machines en aéronautique optimisation du filtrage by Chaiyan Jettanasen( Book )

2 editions published in 2009 in French and held by 2 WorldCat member libraries worldwide

In power electronics field, in order to improve the efficiency of functioning of converter-machine associations, the semiconductors used in PWM inverters operate at higher switching frequencies; this has generated restrictive electromagnetic interference (EMI). During this study, we are particularly interested in common mode (CM) conducted noise emissions that are the most disturbing in this kind of system. These disturbances will not only deteriorate motor bearings but also propagate to electrical network and generate radiated emissions that could create malfunctions in sensitive avionic surrounding equipments, especially the embedded electronics. These disturbances, which are a part of Electromagnetic Compatibility (EMC) problems, are increasingly attracting the attention of industry, particularly in the aeronautical field that is moving towards a generation of “more electric” aircraft. To ensure the reliability of the entire system, EMC standards (ex. DO-160D in aeronautics) have to be respected. The system modelling is the starting point of this work. The chosen approach, called “two-port network”, is based on specific measurements of the CM voltage generated by the inverter, and of equivalent CM impedances of each component of the system, which is represented by a two-port network associated with an impedance matrix [Z]. This simple, efficient and versatile modelling approach enables us to estimate or calculate directly CM currents and CM voltages at various parts of the system in the frequency domain. The comparison with experimental results shows the validity of the model on a wide frequency range. This model is then used for sensitivity studies and finding solutions to reduce CM disturbances. Finally, a model, taking into account the CM currents flowing through the ground plan, has proposed a modelling close to a real variable-speed drive system installed in industry or on an airplane
Modélisation de l'interaction champ électrique-particules diélectriques entre effets électromécaniques et aspects électrocinétiques : application aux cellules biologiques by Abdellah Ogbi( Book )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

In this work, we investigate about the interaction between electrical fields and dielectric particles in the dielectrophoretic phenomena, in theorical and numerical ways. The long-term application are related to electromanipulation and caracterisation of biological cells. Understanding these phenomena requires a complete modeling of polarization mechanisms governing the field-particle interaction and implements electromechanical and electrokinetic models. After introducing the necessary concepts and phenomena, we address polarization modeling using potential theory and suggest an approach for a numerical determination of polarization coefficients. We show that if the multipolar expansion can be reduced to the first order for the case of a spherical particle immersed in a uniform field, the higher orders are needed for nonspherical particles. We show also how a homogenization process allows the study of multilayered particles configurations using this approach. As part of the electromechanical study of dielectrophoretic phenomena, we implement the multipolar approach for two applications numerically treated. We show the relevance of this approach to calculate the force and torque exerted on a particle in situations where the applied field has strong non-uniformities, where the classical dipole approach turn out to be much less efficient. The particle and the suspending medium are in reality two media in contact but not independent as some electrokinetic phenomena occur at the interface. These interfacial effects are addressed in order to be taken into account in the electrorotation phenomenon of a biological cell. The model dealing with the whole problem of a charged spherical particle immersed in a suspension medium and subjected to a rotating field and taking into account the electroosmotic effects is treated. The resolution of the corresponding coupled problem using the finite element method shows the relevance of this approach
Etude du comportement de la jonction émetteur-base d'un transistor silicium à très haute densité d'intégration by Dominique Sebille( Book )

1 edition published in 1982 in French and held by 2 WorldCat member libraries worldwide

Le but de ce travail était la caractérisation de l'effet de la réduction des dimensions d'un transistor bipolaire sur les caractéristiques électriques. Pour cela, on a utilisé une méthode de mesure du gain interne en faible multiplication. Une étude de l'interface si(p)-sio::(2) de la jonction émetteur-base a été entreprise. La modification de l'état électronique de la surface du silicium a été réalisée à l'aide d'un microscope électronique à balayage
A piecewise-affine approach to nonlinear performance by Sergio Waitman( )

2 editions published in 2018 in English and held by 2 WorldCat member libraries worldwide

When dealing with nonlinear systems, regular notions of stability are not enough to ensure an appropriate behavior when dealing with problems such as tracking, synchronization and observer design. Incremental stability has been proposed as a tool to deal with such problems and ensure that the system presents relevant qualitative behavior. However, as it is often the case with nonlinear systems, the complexity of the analysis leads engineers to search for relaxations, which introduce conservatism. In this thesis, we focus on the incremental stability of a specific class of systems, namely piecewise-affine systems, which could provide a valuable tool for approaching the incremental stability of more general dynamical systems.Piecewise-affine systems have a partitioned state space, in each region of which the dynamics are governed by an affine differential equation. They can represent systems containing piecewise-affine nonlinearities, as well as serve as approximations of more general nonlinear systems. More importantly, their description is relatively close to that of linear systems, allowing us to obtain analysis conditions expressed as linear matrix inequalities that can be efficiently handled numerically by existing solvers.In the first part of this memoir, we review the literature on the analysis of piecewise-affine systems using Lyapunov and dissipativity techniques. We then propose new conditions for the analysis of incremental L2-gain and incremental asymptotic stability of piecewise-affine systems expressed as linear matrix inequalities. These conditions are shown to be less conservative than previous results and illustrated through numerical examples.In the second part, we consider the case of uncertain piecewise-affine systems represented as the interconnection between a nominal system and a structured uncertainty block. Using graph separation theory, we propose conditions that extend the framework of integral quadratic constraints to consider the case when the nominal system is piecewise affine, both in the non-incremental and incremental cases. Through dissipativity theory, these conditions are then expressed as linear matrix inequalities.Finally, the third part of this memoir is devoted to the analysis of uncertain Lur'e-type nonlinear systems. We develop a new approximation technique allowing to equivalently rewrite such systems as uncertain piecewise-affine systems connected with the approximation error. The proposed approach ensures that the approximation error is Lipschitz continuous with a guaranteed pre-specified upper bound on the Lipschitz constant. This enables us to use the aforementioned techniques to analyze more general classes of nonlinear systems
Commande et stabilité des systèmes commutés : Application Fluid Power by Omar Ameur( Book )

2 editions published in 2015 in French and held by 2 WorldCat member libraries worldwide

This work focuses on the control and stability analysis of an electro-pneumatic system, i.e. a linear pneumatic cylinder controlled by two servo valves regulating the mass flow entering each chamber of the actuator. The general problem is motivated by the appearance of stick-slip on the electro-pneumatic system, hardly taken into account by the current studies in automatic control. This problem, encountered throughout the years, concerns all mono- and multidimensional linear and non-linear controls systems studied at the laboratory. In pneumatic cylinders, the phenomenon consists in a displacement of the rod a while after it has come to a rest ; this is due to the fact that the force acting on the rod initially becomes smaller that the threshold which is necessary for a motion, and then this threshold is overcome later on. In this case, stick-slip is caused by the presence of dry friction and by the pressure dynamics in the chambers, which continue to evolve (integrating the net incoming mass flow from the servovalves) even after the rod has stopped. The first part of this thesis proposes a nonlinear switching control law in order to avoid stick-slip on pneumatic cylinder, taking into account with the variations of dry friction that may occur at any time causing this phenomenon. This technique is implemented and its effectiveness is recognized. The greatest part of this thesis deals with the stability analysis of the pneumatic cylinder with its switched control law. The presence of dry friction and the application of a switched control law requires an appropriate method for approaching the stability analysis ; this method is based on considering the closed-loop system as belonging to a class of switched systems called piecewise affine systems (PWA). The main difficulty in this approach lies in obtaining adequate Lyapunov functions for proving stability, which turns into an optimization problem under LMI constraints (Linear Matrix Inequality) using the S-procedure. In order to analyze the stability of a PWA system, a first method is proposed allowing the computation of a piecewise quadratic Lyapunov function through an optimization problem under LMI constraints. The methods takes into account, in contrast to conventional methods, that the states might converge not to a single point but to a set of equilibrium points. The proposed approach allows also the study of robustness with respect to parametric variations in the system. A second method is also proposed for the construction of a type of Lyapunov functions called piecewise polynomial, using the “sum of squares” and “power transformation” techniques. This approach proposes less conservative sufficient conditions than those imposed by the piecewise quadratic Lyapunov functions, yielding a more succesfull stability test when for PWA systems featuring sliding modes and parametric variations. In fact, on PWA systems with discontinuous dynamics (which can generate sliding phenomena), piecewise quadratic Lyapunov functions might prove ineffective to prove the stability. Therefore, the results on piecewise quadratic Lyapunov functions are extended in order to compute piecewise polynomial Lyapunov functions of higher order, by solving an optimization problem under LMI constraints. These functions are more general and allow less conservative conditions compared to those formerly developed in the literature. Both of these methods have been applied to the stability analysis of the set of equilibrium points of the pneumatic cylinder, considering first a friction model in saturation form and then a model in relay form with a discontinuous dynamics. The application of the methods is successful, i.e. the robust stability is proven under dry friction threshold variations, with possibility of sliding modes
Caractérisation électrique des tissus biologiques et calcul des phénomènes induits dans le corps humain par des champs électromagnétiques de fréquence inférieure au GHz by Laurent Bernard( Book )

2 editions published in 2007 in French and held by 2 WorldCat member libraries worldwide

This work is part of a process aiming at evaluating and improving the performances of existing tools for the study of the interactions between the electromagnetic fields and the human body. The tools include characterisation methods to measure the macroscopic electrical properties of biological media, and numerical methods allowing to model and compute the fields induced by electromagnetic sources in the human body. The main properties of biological tissues are first described in order to explain the difficulties of their electrical characterisation. The existing characterisation methods are presented. Their specificities and operating frequency range are emphasized. Permittivity and conductivity values found in the literature are used to show the main parameters they depend on and the lack of knowledge on their accuracy. A usual characterisation method based on four-electrode impedance measurements is then studied between 10Hz and 10MHz. The measurement system is developed and tested on ionic solutions in order to build reliable and complete models. These models are used to estimate the accuracy of the measure and to optimize the characterisation method at 10Hz and 10MHz. Various numerical methods that allow modelling and computing induced electromagnetic phenomena in the body are then presented. The difficulties of the modelling are explained and linked to the unusual electrical and geometrical properties of the human body, and to the diversity of the sources of electromagnetic fields. Formulations and boundary conditions especially developed for the problem are described. Using the finite element method, and assuming the electrical properties of the body are known, various models (mesh, formulation, boundary conditions) are studied. Their efficiency is evaluated by simulating 2D and 3D representative canonical problems. The results allow estimating the accuracy of the computation and choosing the more efficient modelling for each frequency between 10Hz and 1GHz. The work gives arguments which can be used to prove the consistency of the results when studying the interaction between the electromagnetic fields and the human body. It has also direct applications in the accurate characterisation of biological media and in the establishment of new norms on human exposure to electromagnetic fields
Développement multipolaire en harmoniques sphériques et propagation des incertitudes appliqués à la modélisation de source de rayonnement en compatibilité électromagnétique by Zhao Li( )

2 editions published in 2017 in French and held by 2 WorldCat member libraries worldwide

With the advances in technology, the power density of electrical equipment is increasing, which leads to an increase in electromagnetic interference between two power electronic systems. This interference may cause the electronic equipment to malfunction. In order to avoid such problems, a large number of experimental verifications are necessary after the development of a prototype, which leads to a significant additional cost in its industrial cycle. This thesis aims at taking into account the problems of near-field electromagnetic compatibility in the design phase of a product. The method is based on the development in spherical harmonics of the parasitic radiation generated by the devices or the components of the device. The harmonic coefficients of a device make it possible not only to model its near field by a punctual source, but also to determine the inductive coupling with the others. In this context, the multipole expansion method is studied theoretically, numerically (by the software Flux3D) and experimentally in this work. In this document, the new automated measuring system is presented and different approaches related to the solution of this problem are then studied, such as the optimal choice of the development origin, the error compensation of the measurements due to the secondary sources, the study of the propagation of uncertainty in the inverse problem and how to take into account the a priori information, etc
Analyse spatiale et multi-échelle de la distribution des bactéries dans le sol et les sédiments by Jean-Sébastien Beaulne( Book )

2 editions published in 2015 in French and held by 2 WorldCat member libraries worldwide

The bacteria have colonized all the niches of the planet. Specifically, soils are home of the largest terrestrial biodiversity, microbial fauna. This great diversity of bacteria and their relative ubiquity make it difficult to idendified variables driving the spatial distribution of bacteria living in the soil. As soil bacteria play a significant role in the main global biogeochemical cycles, it is important to better understand the variables that can influence bacterial composition of soils. In this thesis, we hypothesize that heterogeneity of the bacterial community composition appears at the same scale level as the heterogeneity of soil physicochemical properties. In order to understand the relationship of bacterial composition of soils (from core experiment to field study in large region in the northern France) and soil factors at different spatial scales, we will use an approach coupling GIS tools, soil physico-chemical analysis and 16S rRNA gene NGS. With Three set of experiment we will answer three questions: Can a uniform environmental pressure at a larger scale (cm) overcome microbial micro-scale heterogeneity? Are geographical gradients strong drivers of the microbial community structure at the scale of the gradient? Do large-scale geographical features that integrate groups of parameters model the differences in microbial community structure for an entire region?
Nouvelle approche de décryptage de la diversité bactérienne environnementale par capture magnétique de populations spécifiques de bactéries au sein de microbiotes complexes by David Royet( )

2 editions published in 2017 in French and held by 2 WorldCat member libraries worldwide

Les bactéries, organismes les plus abondants de notre planète, ont un rôle fondamental dans le fonctionnement des écosystèmes. En dépit de leur importance, la caractérisation des communautés bactériennes (microbiotes) demeure encore aujourd'hui très incomplète. Ceci a pour origine l'impossibilité de complètement décrypter taxonomiquement et fonctionnellement les microbiotes de ces écosystèmes et donc à appréhender la diversité bactérienne dans son ensemble que ce soit par des approches culturales (avec seulement 1% de bactéries cultivables) ou par des approches metagénomiques limitées par les biais d'extraction, de séquençage et d'analyse. Les travaux entrepris dans le cadre de cette thèse visent à développer une nouvelle voie exploratoire passant par le fractionnement des microbiotes afin d'en étudier séparément les génomes des différentes populations ou groupes de populations, leur somme devant permettre de reconstituer un metagénome complet. Cet objectif requiert le développement d'un outil pour la sélection spécifique de bactéries (sur des critères taxonomiques ou fonctionnels) et leur isolement du reste des microorganismes non ciblés. Les travaux de thèse ont porté sur le développement d'une approche de marquage magnétique des bactéries basée sur l'hybridation moléculaire (hybridation in situ) complétée par celui d'un outil de tri microfluidique. Deux méthodes ont été développées, MISH et HCR, ciblant le gène de l'ARNr 23S, chacune reposant sur la formation, lors du processus d'hybridation, d'une structure secondaire en arborescence (MISH) ou ordonnée (HCR) permettant le greffage de nanoparticules magnétiques. Les résultats obtenus illustrent le potentiel des deux approches d'abord pour le marquage spécifique de bactéries cibles (E.coli et Pseudomonas putida) en conditions de culture au laboratoire puis dans un second temps dans des échantillons de sol. Le tri microfluidique a également été optimisé par le développement d'un nouveau dispositif de tri magnétique permettant la séparation des cellules marquées sous flux continu faisant appel à l'injection d'un polymère composite magnétique pour intégrer au fond du microcanal une série de bandes parallèles magnétiques. La fonctionnalité du dispositif a été démontrée, sa simplicité de fabrication en faisant un outil de choix pour une application en routine dans les laboratoires d'écologie microbienne. En dépit de résultats prometteurs toute cette nouvelle approche d'étude de la diversité bactérienne environnementale nécessite encore de nombreuses étapes d'optimisation
Modélisation des réseaux électriques ferroviaires alimentés en courant alternatif by Pierre Fayet( Book )

2 editions published in 2008 in French and held by 2 WorldCat member libraries worldwide

The study of AC-fed railways electrical networks requires to determine the peak and mean values that may be reached by the electrical variables versus time for a given traffic running on all the lines inside the study domain. Modelling these networks leads to the determination of these physical values and gives a practical answer to the needs of the users wishing to study their sizing and running. First, a decomposition of the railway system into elementary subsystems and their modelling are detailed, emphasizing the subject specificities, especially the energy's transportation line representation. Then the integration of these models is presented in order to simulate the running of a railways network, including crossings, loop lines etc. Based on the modelling, many sensitivity studies are carried out, in order to test and validate the choices of the models and to identify the significant parameters in the networks sizing. The architecture of the software is shown, and many simulation results are obtained on typical examples. At last, some tests are carried out on a real case, the comparisons with measurements seem in satisfactory agreement
Prédiction de la structure de contrôle de bactéries par optimisation sous incertitude by Marouane Ait El Faqir( )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

L'approche de la biologie des systèmes vise à intégrer les méthodologies appliquées dans la conception et l'analyse des systèmes technologiques complexes, au sein de la biologie afin de comprendre les principes de fonctionnement globaux des systèmes biologiques. La thèse s'inscrit dans le cadre de la biologie des systèmes et en particulier dans la prolongation d'une méthode issue de ce cadre : la méthode Resource Blance Analysis (RBA). Nous visons dans cette thèse à augmenter le pouvoir prédictif de la méthode via un travail de modélisation tout en gardant un bon compromis entre représentativité des modèles issus de ce cadre et leur résolution numérique efficace. La thèse se décompose en deux grandes parties : la première vise à intégrer les aspects thermodynamiques et cinétiques inhérents aux réseaux métaboliques. La deuxième vise à comprendre l'impact de l'aspect stochastique de la production des enzymes sur le croissance de la bactérie. Des méthodes numériques ont été élaborées pour la résolution des modèles ainsi établis dans les deux cas déterministe et stochastique
Modélisation de la tenue diélectrique dans les grands intervalles d'air : application aux intervalles complexes by Lamine Boubacar Konate( )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

This thesis is devoted to the study of the positive discharge in large air gaps. The initial goal is to develop a model able to determine the voltage U50 and the k-factor, two important factors involved in the design of high voltage structures in complex geometries. To do this, a review of the discharge models available in the literature was done. We chose the circuit model developed by Professor Beroual's group and applied to the positive discharge and also to the negative discharge. This model is based on an equivalent circuit diagram, his parameters varying with time according to the leader channel characteristics and the geometry of the discharge. The spread of the leader is based on a criterion related to the calculation of the field at its head and where the randomness of the discharge path is taken into account. As most of models found in the literature, this model applies only to the point-plane type interval. Part of this work was to extend the domain of applicability of this model to complex geometries. A detailed study of the rod-rod gap allowed us to validate our model in its ability to simulate an example of complex geometry. Moreover, experimental tests allowed us to compare the value of the U50 voltage determined using our model and the one from experiments for to this rod-rod geometry. The results are in good agreement with a margin of error of less than 5%. Given the good agreement resulting from the confrontation model - laboratory experience and the great similarity, large spark - atmospheric discharge, a positive lightning model was developed. This model allowed us to use for the first time the circuit model to model the lightning attachment process. The results obtained allow to validate the feasibility to find, to the standard methods of protection against lightning, digital alternative based on a simulation of lightning. An estimate of the field radiated by the leader channel was performed. This opens a way for the study of the interaction of these fields radiated with engineering systems
Modélisation CEM des équipements aéronautiques : aide à la qualification de l'essai BCI by Hassan Cheaito( )

2 editions published in 2017 in French and held by 2 WorldCat member libraries worldwide

L'intégration de l'électronique dans des environnements sévères d'un point de vue électromagnétique a entraîné en contrepartie l'apparition de problèmes de compatibilité électromagnétique (CEM) entre les différents systèmes. Afin d'atteindre un niveau de performance satisfaisant, des tests de sécurité et de certification sont nécessaires. Ces travaux de thèse, réalisés dans le cadre du projet SIMUCEDO (SIMUlation CEM basée sur la norme DO-160), contribuent à la modélisation du test de qualification "Bulk Current Injection" (BCI). Ce test, abordé dans la section 20 dans la norme DO-160 dédiée à l'aéronautique, est désormais obligatoire pour une très grande gamme d'équipements aéronautiques. Parmi les essais de qualification, le test BCI est l'un des plus contraignants et consommateurs du temps. Sa modélisation assure un gain de temps, et une meilleure maîtrise des paramètres qui influencent le passage des tests CEM. La modélisation du test a été décomposée en deux parties : l'équipement sous test (EST) d'une part, et la pince d'injection avec les câbles d'autre part. Dans cette thèse, seul l'EST est pris en compte. Une modélisation "boîte grise" a été proposée en associant un modèle "boîte noire" avec un modèle "extensif". Le modèle boîte noire s'appuie sur la mesure des impédances standards. Son identification se fait avec un modèle en pi. Le modèle extensif permet d'étudier plusieurs configurations de l'EST en ajustant les paramètres physiques. L'assemblage des deux modèles en un modèle boîte grise a été validé sur un convertisseur analogique-numérique (CAN). Une autre approche dénommée approche modale en fonction du mode commun (MC) et du mode différentiel (MD) a été proposée. Elle se base sur les impédances modales du système sous test. Des PCB spécifiques ont été conçus pour valider les équations développées. Une investigation est menée pour définir rigoureusement les impédances modales. Nous avons démontré qu'il y a une divergence entre deux définitions de l'impédance de MC dans la littérature. Ainsi, la conversion de mode (ou rapport Longitudinal Conversion Loss : LCL) a été quantifiée grâce à ces équations. Pour finir, le modèle a été étendu à N-entrées pour représenter un EST de complexité industrielle. Le modèle de l'EST est ensuite associé avec celui de la pince et des câbles travaux réalisés au G2ELAB. Des mesures expérimentales ont été faites pour valider le modèle complet. D'après ces mesures, le courant de MC est impacté par la mise en œuvre des câbles ainsi que celle de l'EST. Il a été montré que la connexion du blindage au plan de masse est le paramètre le plus impactant sur la distribution du courant de MC
Implication des champignons et des bactéries dans le cycle de l'azote et la production de N2O dans le sol by Christoph Keuschnig( )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

The main objective of this thesis is to determine the role of microbial communities in N2O emissions from soil, and more specifically to define to what extent fungi are involved. Therefore, their community structure at the micro scale, their behavior in reducing nitrogen and producing N2O, and their impact on nitrogen cycling communities as decomposers in soil were investigated. Analysis of soil fractions of unmanaged, pristine Rothamsted Park Grass soil showed that fungal communities change within isolated fractions in contrast to bacterial communities. Also, nitrifying, denitrifying and N2O reducing potentials were detected in all fractions and found to be linked to carbon and nitrogen chemistry. Pure culture experiments on 24 fungal strains quantifying NO and N2O production from nitrite showed that Fusarium species are true N2O producers among fungi. Monitoring NO revealed that nitrite medium is unstable under anoxic conditions and produces NO abiotically, which implies that low N2O producing strains are actually detoxifying this NO rather than respiring it, as previously assumed. The lack of a nirK - p450nor in most fungi supported this hypothesis. Interspecies relationships between fungi and bacteria were studied following community development after organic matter addition. Different organic amendments triggered distinct responses of a soil community with respect to bacterial and fungal activity. Functional signatures identified in this study corroborated our hypothesis that fungi are involved in N2O production by influencing a N-cycling bacterial community via carbohydrate degradation processes. The results from this thesis provide a basis for exploring interspecies relationships in nitrogen cycling processes in soil and mark a step towards integrating all members of the community in soil ecosystem research
Interfaces sigma-delta avancées pour capteur de champ magnétique microfluxgate by Fabrice Gayral( Book )

2 editions published between 2007 and 2009 in French and held by 2 WorldCat member libraries worldwide

The microfluxgate sensor is a miniaturized device that measures the magnetic field. Its resolutioncompared to its small size makes him a leader on the accurate micro magnetic field sensors market. For now used in electronic compass or motion capture applications, it will in the near future be a candidate for applications requiring a much higher resolution. In this context, this PhD thesis focuses on the design of an integrated analog/digital interface which will enable to take better advantage of the high performances of the microfluxgate sensor. We have developed a new functioning technique for the microfluxgate sensor, that takes advantage of the intrinsic characteristics of the miniaturized fluxgate sensor. This new method enables to enhance the sensor's performances while diminishing the constraints on the analog detection electronic, and reducing the consumption of the system. We present the design of an integrated circuit in a 0,35 micron CMOS technology, based on this new technique, that includes a low-pass Sigma-Delta detection and modulation, and a digital feedback control. Promising test results of the circuit lead to envision the design of an adjustable architecture which will enable the real-time tradeoff between consumption and resolution
Modélisation des systèmes de mise à la terre des lignes électriques soumis à des transitoires de foudre by Xavier Legrand( Book )

2 editions published in 2007 in French and held by 2 WorldCat member libraries worldwide

The PhD Thesis deals with the modelling of grounding systems of transmission lines with particular reference to the transient phenomena occurring when the conductors of these lines are struck by a lightning stroke. The first part presents the description of the role of grounding systems in transmission lines ; then it contains a brief summary of lightning phenomenology and of the main phenomena involved in the problem of interest. This part of the thesis serves as a base for the next developments as it is devoted to the analysis of the parameters that have the most important influence on the lightning response of the grounding system, withe particular concern on the mechanicsm of the diffusion of the current into the ground. The second part covers the response in the frequency domain of grounding system. The main models proposed in the literature are briefly analysed and one of them, the so-called electromagnetic model, is chosen as reference for the following developments. The choise is justified by thorough theoretical analysis and by comparison with experimental results obtained at the candidate's laboratory. Such a model is then employed in order to find some general criteria aimed at optimizing the structure of the grounding systems of interest. The third part of the thesis is devoted to the development of an innovative procedure ; aim of this procedure is to include the earlier mentioned reference model of grounding systems into transient analysis programs based on circuit and line theory, such as the Electromagnetic Transient Program (EMTP). The aim is to provide a "time-model" of grounding systems, to be used for transients studies. The developed approach allows the representation by means of state equations implemented in the revised version of the EMTP RV of a complex grounding system, having an arbitary number of electrical connections with the transmission system. Such a result is of particular importance for advanced insulation coordination studies and, more in general, for EMC problems involving grounding systems. The developed tool allows also, fourth part of the thesis, for analysis on the propagation of transient phenomena by ground electrodes, with the final aim of evaluating lightning deleterious effects on burien cables and on humans, with reference for this case to step and contact voltages. Cable modelling and risk evaluation for humans with reference to the problem of interest are two points dealt with too in this part of the dissertation. Finally, a part is devoted to the development of an effective numeric method to compute the so-called Pollaczek integral, used in the literature to compute the mutual impedance between an overhead and another overhead/underground conductor of the earth-return impedance of an underground cable, although they give origin to numerical complexities that often lead to use of simpligied models
Contribution à la modélisation tridimensionnelle des interactions champ électromagnétique Corps humain en basse fréqences by Le Ha Hoang( Book )

2 editions published in 2007 in French and held by 2 WorldCat member libraries worldwide

Micro-nanostructures à base de cristaux photonique pour le contrôle 3D de la lumière by Lydie Ferrier( Book )

2 editions published in 2008 in French and held by 2 WorldCat member libraries worldwide

Modélisation dynamique des décharges se propageant sur des surfaces isolantes polluées avec des dépôts discontinus sous différentes formes de tension by Simeon Diampeni Kimbakala( Book )

2 editions published in 2007 in French and held by 2 WorldCat member libraries worldwide

This work presents an antonomous and dynamic model of prediction of the characteristics of discharges propagating on polluted insulating surfaces in a discontinuous way, based on the energy balance, the equivalent electric circuits, and the physical characteristics of the arc. This model allows to determine the various parameters of the discharge until the flashover by taking into account the insulator geometry, the change of resistance during the propagation, the type of pollution band and its characteristics (conductivity, thickness, width, position compared to the electrodes). The voltage evolution at the head of arc and the voltage drop within the arc are analyzed according to the kind of applied voltage. It is shown that the location of the pollution bands with regards to the electrodes, their widths, their thicknesses and their conductivities (weakly or strongly polluted) have significant influence on the parameters of the discharge. The increase of thickness of the pollution band leads to the increase of the resistance of the arc and to the reduction of the accumulated charge and thus to the decrease of the charging current. Note that the thicker the pollution layer, the shorter the time to flashover of the insulator is. Moreover, the flashover voltage is all the smaller as the flashover time is long. The high conductivity of the pollution layers generates high currents. The higher the ratio between the conductivities of the various bands, the higher the current and the charge are ; this can be explained by the remarkable increase of the radius of the discharge channel. The evolution of velocity follows those of the currents and electrical charges
 
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Alternative Names
Centre national de la recherche scientifique (France). Unité de recherche associée (5005)

Ecole centrale de Lyon. Département Electronique Electrotechnique Automatique, EEA. Laboratoire AMPERE

Ecole centrale de Lyon. Laboratoire AMPERE

Ecully (Rhône)

Laboratoire AMPERE (Ecully, Rhône)

Languages
French (36)

English (2)