Дисертації з теми "Modélisation des charges"
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Hudon, Philippe. "Modélisation de puits géothermiques par charges horaires." Mémoire, École de technologie supérieure, 2012. http://espace.etsmtl.ca/1021/1/HUDON_Philippe.pdf.
Susetyo, Budi. "Modélisation de l'impédance harmonique de charges agrégées." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0027.
Vauchelet, Nicolas. "Modélisation mathématique du transport diffusif de charges partiellement quantiques." Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00135114.
mathématique du transport d'électrons confinés dans une nanostructure
dans le but d'implémenter des simulations numériques. Dans de tels
dispositifs nanométriques, les ordres de grandeurs ne jouent pas le
même rôle dans chaque direction. Les électrons peuvent être
extrêmement confinés dans une ou plusieurs directions. Un modèle
quantique est nécessaire pour décrire le confinement. Dans la
direction non confinée, le transport est supposé de nature classique.
Nous proposons alors un système couplé quantique/classique.
Les collisions intervenant lors du transport induisent un régime
diffusif des porteurs de charges. Le modèle diffusif est obtenu grâce
à une limite de diffusion d'un modèle cinétique. L'analyse
mathématique de cette limite de diffusion et du modèle diffusif couplé
sont présentées. Une simulation numérique du transport dans un
nanotransistor est obtenue avec ce modèle.
Lassoued, Rachid. "Modélisation analytique des structures unidimensionnelles et bidimensionnelles sous charges mobiles." Marne-la-Vallée, 2007. http://www.theses.fr/2007MARN0328.
Banda, Gnama Mbimbiangoye Mallys Elliazar. "Mesure et modélisation du comportement de matériaux diélectriques irradiés par faisceau d'électrons." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30208/document.
In their common uses as electrical insulators, organic solid materials are constitutive of electric power transmission cables, power control and conversion circuits as well as (micro) electronic components or embedded systems (thermal coating of satellites, batteries of accumulators, etc.). Under various constraints of use (electric field, radiation, temperature, humidity ...) they can accumulate charges in their bulk which could affect the reliability of the systems in which they are employed. One of the commonly used means to study the electrical behavior of these charges is to measure the spatiotemporal distribution of charges by subjecting the dielectrics to a continuous potential difference between two electrodes. However, this method does not always allow clearly distinguishing the contribution of charges due to generation on the one hand and the one due to transport phenomena on the other hand. This study proposes an alternative approach, consisting in generating charges (electrons) within the electrical insulation using an electron-beam under vacuum. The charges are hence deposited at a known position and in a controlled quantity. Other physical processes related to the implantation of electrons must then be taken into account in order to predict and model the behavior of these irradiated materials. Low-density polyethylene (LDPE) films, prepared by thermal molding, were irradiated by a 80 keV electron-beam with a current flux of 1 nA/cm2. Space charge measurements using the Pulsed Electro-Acoustic (PEA) method, performed first in-situ and then ex-situ under DC electrical polarization, confirm an effective localization of charges within the material. The results under electrical polarization after irradiation show an important amount of positive charges in the irradiated zone of the dielectric. The electrical characterizations of irradiated LDPE films show a completely different behavior compared to the same non-irradiated material, suggesting a modification of the chemical structure of the material. Physico-chemical measurements (infrared spectroscopy, Photoluminescence and Differential Scanning Calorimetry-DSC) on these irradiated PEbd films do not show a significant degradation of the chemical structure of the dielectric which would explain the observed electrical behavior under post-irradiation polarization. Additional measurements show the reversible behavior of the irradiated then polarized PEbd, which would be only related to the presence of the charges generated by the beam. The experimental data of this study have simultaneously fed a numerical model of charge transport, developed to take into account the irradiation constraints. This model allows reproducing the in-situ results of charge implantation by the electron beam as well as the majority of the electrical processes observed on irradiated and polarized LDPE. It confirms the impact of the electron-beam deposited charge on the behavior under polarization and allows concluding on the origin of the positive charges observed after irradiation, which would be due to injection at the electrodes as well as to the creation of electron-hole pairs by the electron-beam during irradiation
Xu, Boyang. "Compréhension et modélisation de flammes d'essence à fortes charges et fortes dilutions." Thesis, Institut polytechnique de Paris, 2019. http://www.theses.fr/2019IPPAE003.
Reducing CO2 and pollutant emission is the essential challenge when dealing with climate change problems. In the transport sector, exhaust gas recirculation (EGR) technology is often used in turbocharged gasoline spark ignition (SI) engines to increase fuel economy, inhibit knock tendency, and reduce NOx emissions. However, high EGR ratios are still difficult to achieve, as they result in reduced heat release and engine stability. As increasing turbulence level and advance spark ignition systems could not bring sufficient improvements at such extreme conditions, growing interest is cast onto the combustion chemistry under high dilution. The present work aims to understand the combustion chemistry of highly-diluted gasoline premixed flames and to establish a detailed kinetic mechanism by multi-scale modeling to predict combustion characteristics with sufficient accuracy at highly-diluted conditions.This work adopts a multi-scale modeling approach, and targets on the laminar flame speed (SL) of a gasoline surrogate, which is named toluene reference fuel with ethanol addition (TRFE) and consist of isooctane, n-heptane, toluene, and ethanol. For micro-scale modeling, the reaction between ketene and hydroxyl radical, which might be important to the SL at highly-diluted conditions, is studied theoretically using ab initio electronic structure methods for the potential energy surface (PES) and Rice–Ramsperger–Kassel–Marcus Theory coupled with Master Equation (RRKM/ME) for the rate coefficients. Detailed PES is obtained, dominant pathways are identified, and their phenomenological rate coefficients are derived to be utilized in combustion modeling. For macro-scale modeling, firstly, important kinetic, thermodynamic, and transport parameters to the laminar flame speed at highly-diluted conditions, are firstly identified using sensitivity analysis based on a starting mechanism. Sensitive reactions are found to mostly involve HO2, C2--C3 species and fuel radicals. Secondly, in the sub-mechanisms where these reactions lies, diluted flames of the corresponding fuels are studied and chemical detail of the dilution effects are explored. The starting mechanism is updated by state-of-the-art kinetics parameters found in the literature for each sub-mechanisms. Finally, a detailed mechanism suitable for laminar flame speed calculations at highly-diluted conditions is established after validation. A mathematical SL correlation is generated for the use in computational fluid dynamic (CFD) simulations
Xu, Boyang. "Compréhension et modélisation de flammes d'essence à fortes charges et fortes dilutions." Electronic Thesis or Diss., Institut polytechnique de Paris, 2019. http://www.theses.fr/2019IPPAE003.
Reducing CO2 and pollutant emission is the essential challenge when dealing with climate change problems. In the transport sector, exhaust gas recirculation (EGR) technology is often used in turbocharged gasoline spark ignition (SI) engines to increase fuel economy, inhibit knock tendency, and reduce NOx emissions. However, high EGR ratios are still difficult to achieve, as they result in reduced heat release and engine stability. As increasing turbulence level and advance spark ignition systems could not bring sufficient improvements at such extreme conditions, growing interest is cast onto the combustion chemistry under high dilution. The present work aims to understand the combustion chemistry of highly-diluted gasoline premixed flames and to establish a detailed kinetic mechanism by multi-scale modeling to predict combustion characteristics with sufficient accuracy at highly-diluted conditions.This work adopts a multi-scale modeling approach, and targets on the laminar flame speed (SL) of a gasoline surrogate, which is named toluene reference fuel with ethanol addition (TRFE) and consist of isooctane, n-heptane, toluene, and ethanol. For micro-scale modeling, the reaction between ketene and hydroxyl radical, which might be important to the SL at highly-diluted conditions, is studied theoretically using ab initio electronic structure methods for the potential energy surface (PES) and Rice–Ramsperger–Kassel–Marcus Theory coupled with Master Equation (RRKM/ME) for the rate coefficients. Detailed PES is obtained, dominant pathways are identified, and their phenomenological rate coefficients are derived to be utilized in combustion modeling. For macro-scale modeling, firstly, important kinetic, thermodynamic, and transport parameters to the laminar flame speed at highly-diluted conditions, are firstly identified using sensitivity analysis based on a starting mechanism. Sensitive reactions are found to mostly involve HO2, C2--C3 species and fuel radicals. Secondly, in the sub-mechanisms where these reactions lies, diluted flames of the corresponding fuels are studied and chemical detail of the dilution effects are explored. The starting mechanism is updated by state-of-the-art kinetics parameters found in the literature for each sub-mechanisms. Finally, a detailed mechanism suitable for laminar flame speed calculations at highly-diluted conditions is established after validation. A mathematical SL correlation is generated for the use in computational fluid dynamic (CFD) simulations
Wanderley, Cavalcanti Marco Antonio. "Etude expérimentale des performances d'un thermosiphon diphasique et modélisation." Lyon, INSA, 1998. http://www.theses.fr/1998ISAL0069.
This theoretical and experimental study aims to determine the effect of various parameters - heat transfer rate, fill charge, tilt angle, operating temperature - on the global thermal resistance of a two-phase closed thermosyphon. The experimental set-up is made of a cylindrical copper tube, filled with R-113. The heat flux supplied to the evaporator section vanes between 0 and 10 W/cm2. The condenser section is cooled by a forced convective water flow. The performances are better. For high operating temperatures and, at a fixed temperature, the global thermal resistance exhibits an optimum value as the heat transfer rate increases An optimum tilt angle was found. A thermosyphon model was developed. The condenser section is divided into elliptical sub volumes, corresponding to the intersection of the tilted tube with vertical planes. The local heat transfer coefficient is calculated using the Nüsselt theory, modified to take into account the elliptical geometry and the way film flow. The heat transfer coefficient of the evaporator is calculated using various correlations from the literature. A comparison between the theoretical experimental results was carried out. Although the model does not well predict the transition from the laminar to the turbulent flow of the condensate film, the heat transfer rate and the global thermal resistance predicted by the model are m good agreement with the experimental results
Ferreira, Cristina. "Modélisation de l'hydrotraitement de résidus pétroliers en lit fixe : étude de la réactivité de charges." Lyon, Ecole normale supérieure, 2009. http://www.theses.fr/2009ENSL0551.
To react to the continual changes in the energetic demand, it is necessary to convert petroleum residues into high value fractions. To upgrade the heaviest part of the crude oil the removal of impurities, as sulfur or metals, is a necessary step. Residue hydrotreatment in fixed bed, under high hydrogen pressure achieves high removal performances, with a industrial catalysts optimized staging. This work presents an insight on different geographical origin residues reactivities. A hydrotreatment kinetic model was developed attemping to simulate the different residues performances. Despite the recent improvements, residues remain very difficult to describe and characterize in details. The comparison of different residues rea ctivities has shown a specific behaviour for each residue. One of the key reactivity parameters seems to be the residues molecules size. Small size residues react easier because more molecules access the catalytic sites. The developed model shows the interest of considering diffusion and steric hindrance inside the catalysts and the importance of a residue description in fractions allowing to consider a complex kinetic network. Finally, this new model is able to take into differences in terms of residues characteristics and then leads to fairly good simulations of residues performances
Pereira, De Oliveira Luís Carlos. "Développement d'une méthodologie de modélisation cinétique de procédés de raffinage traitant des charges lourdes." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2013. http://tel.archives-ouvertes.fr/tel-00839871.
Mohamed, Massoud Abdelaal Magdy. "Modélisation et caractérisation de la densité de puissance électromagnétique déposée dans des charges mobiles." Toulouse, INPT, 1999. http://www.theses.fr/1999INPT022H.
Soyez, Laurent. "Contribution à l'étude du comportement des ouvrages de soutènement en sol renforcé, soumis à des charges d'exploitation ferroviaire (charges dynamiques et cycliques)." Phd thesis, Ecole Nationale des Ponts et Chaussées, 2009. http://tel.archives-ouvertes.fr/tel-00596015.
Mouhammad, Al Anfaf Mohamed Mladjao. "Contribution à la modélisation et à l’optimisation de systèmes énergétiques multi-sources et multi-charges." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0127/document.
Global energy demand continues to rise. The fossil fuel prices are unstable and uncertain. The liberalization of the electricity market and environmental awareness of the global leaders are levers for the development of renewable energy. These are growing at a rapid pace in the world. They reached technical maturity that enables them to become an important segment of the energy industry. Their integration in the energy mix poses new challenges compared to traditional energy sources. With an underexploited potential, photovoltaic and wind energy are advantageous economically and environmentally. However, their intermittent decreases their energy efficiency when operated. The use of hybrid systems (multi-sources) combining these renewable energy sources, the national distribution network (historical grid) and conventional storage systems, is generally regarded by all as a future solution, both efficient and reliable. Thereby, it is necessary to rethink the structure of electrical networks and energy markets, and changes in network management methods. In this context, the foreseen intake with this thesis is to contribute to the modeling and optimization of multi- load multi- source systems to power both remote sites “closeness energy” (campus, village) and large sites such as French regions through their interconnection "pooling ". Different scenarios of management and different configurations of the systems are modeled, tested and compared to analyze the effectiveness and robustness of each case. A complete technical and economic analysis is performed in order to study the feasibility of each system. To demonstrate the validation of these models, studies were performed on a French university campus, a Micro-grid in Mali and three French regions. These latter have been applied to an original interconnection model based on Petri nets for decision support in terms of network configuration and control of energy flows exchanged between interconnected producers/consumers territories without storage
Bolinches, Raphae͏̈l. "Modélisation et caractérisation des phénomènes de transport surfacique et volumique de charges électriques dans les polymères." Toulouse 3, 1997. http://www.theses.fr/1997TOU30072.
Cornet, Nadège. "Modélisation numérique et caractérisation de l'injection et du transport de charges dans des isolants céramiques multicouches." Saint-Etienne, EMSE, 2008. http://www.theses.fr/2008EMSE0045.
In industry, a constant aim is to reduce the size of the produced pieces for economic reasons. This can be possible by mastering some properties through a surface layer whose composition is different from that of the bulk material. For example, in order to retain a strong resistance to dielectric breakdowns of insulating ceramic materials, double-layered structures, formed by an insulating substrate covered by a surface layer of a chosen composition, are increasingly considered. Behaviour under injection of charges in these multi-layer materials is generally linked to the intrinsic properties of the surface material: structural, dielectric and geometrical properties. The aim of this work was to determine relationships between the microstructure of material, its behaviour during electron injection and its resistance to dielectric breakdown. This comprehension and the interpretation of the experimental results were possible through the simulation of the injection by the way of a physical model, suggested initially by HJ Fitting and developed by X. Meyza and M. Touzin. Improvements were performed on the initially developed model by taking into account : (i) the effect of the temperature through the introduction of a ‘Poole-Frenkel-like’ detrapping effect on the diffusion current, (ii) the effect of the recombination of the available charges, in particular the ones induced by the effects of detrapping and (iii) the presence of a diffusion current. The model, used until now for bulk materials, was generalized to a multi-layer system. Thus, the influence of the material surface on electron energy, was taken into account by the concept of effective thickness. Then, this model was validated by comparing measurements of output intrinsic and total emission of secondary electrons, resulting from the experimental data, with the simulated results. Finally, the model was applied to the case of double-layered materials: silica-covered alumina, and alumina whose surface was laser-treated. Simulations showed that, even for very thin deposits (comparable with the escape length of the electrons, i. E a few tens of nanometers), the behaviour of covered alumina was strongly modified. In particular, an accumulation of charges near the interface, following a bipolar distribution, was noticed. Confrontation between the simulated results and experimental measurements of electron injections by ICM method (Induced Current Method), eventually made it possible to understand the surface layer influence on the property of the dielectric breakdown behaviour of these covered materials. The surface of an alumina having undergone a laser treatment, is strongly modified and its behaviour under injection of charges as well. The charges are progressively diffusing as they are injected. This diffusive behaviour is confirmed by the simulation of injection in a 100nm-thick layer with physical properties different from that of the substrate (linked to the structural modifications: sweating of the secondary phases, fusion). On the opposite, the behaviour of initial material under charge injection is different: the charges are strongly trapped, generating a surface potential that creates a “barrier” to the injection: this trapping behaviour was highlighted in experiments. These two phenomena make it both possible to increase the dielectric rigidity of materials
Faure, Nicolas. "Modélisation électromagnétique en présence de charges d’espace : application à l’étude de tubes électroniques de type magnétron." Limoges, 2006. http://aurore.unilim.fr/theses/nxfile/default/c0847439-d574-4838-b1c8-f9b3ab431dbb/blobholder:0/2006LIMO0022.pdf.
This work deals with electromagnetic modelisation in the presence of space charges. On the one hand, we developed a Particle-In-Cell code with an algorithm of the Finite Difference Time Domain type. After realisation and validation of a 2D PIC code on a rising sun structure, we extended then validated the code in 3D. In addition, we studied the inherent static and electromagnetic aspects in the electronics tubes of magnetron type operation. This approach allowed us best encircled influence of various elements like the straps and to emit at last certain rules to optimise the synthesis of new sources. This study makes it possible to have codes to optimise or develop new sources
Pinot, Christophe. "Modélisation des diodes électroluminescentes organiques multicouches dopées. Application à de nouvelles architectures." Phd thesis, Ecole Polytechnique X, 2008. http://pastel.archives-ouvertes.fr/pastel-00005744.
Gautrand, Anne. "Étude et modélisation des phénomènes de transfert de charges dans les capteurs d'images à pixels actifs PhotoMOS." École nationale supérieure de l'aéronautique et de l'espace (Toulouse ; 1972-2007), 2000. http://www.theses.fr/2000ESAE0011.
Bedja, Abderrahim. "Modélisation de l'attachement de la décharge de foudre sur un paratonnerre, prenant en compte les charges d'espace." Ecully, Ecole centrale de Lyon, 2006. http://www.theses.fr/2006ECDL0013.
The aim of our thesis is to study the lightning attachment process in the case of the lightning rod installed upon the ground. All phases of propagation of the upward discharge initiated from the lightning rod are taken into account in our work (corona effect, transition corona-ascendant streamer, propagation of the couple streamer-leader). This study contributes to a best comprehension of the influence of the geometry of the lightning rod (height, radius of curvature) on the effectiveness of the rod to intercept the downward discharge
Grizzetti, Bruna. "Modélisation du devenir de l'azote et du phosphore d'origine ponctuelle et diffuse à l'échelle européenne." Paris 6, 2006. http://www.theses.fr/2006PA066041.
Gandois, Laure. "Dynamique et bilan des Elements Traces Métalliques (ETM) dans des écosystèmes forestiers français. Modélisation, spéciation et charges critiques." Phd thesis, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00741901.
Gandois, Laure. "Dynamique et bilan des éléments traces métalliques (ETM) dans des écosystèmes forestiers français : modélisation, spéciation et charges critiques." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/810/.
Trace Metals (TM: Cd, Co, Cu, Cr, Ni, Pb, Sb and Zn) are dispersed in the atmosphere due to both natural and anthropogenic processes. Forest ecosystems can receive atmospheric inputs, even if they are located far from direct emission sources. In fact, forest ecosystems are particularly sensitive to atmospheric inputs since forest cover can interact with atmospheric pollution. Forest ecosystems are protected from TM atmospheric inputs through the definition of Critical Loads. TM impact on forest ecosystem is linked to their dynamic at the atmosphere/vegetation and soil/solution interfaces. Indeed, forest cover modifies atmospheric inputs. Moreover, it is through soil solution that TM are available to the biosphere and can reach ground and surface waters. During this work, TM content and speciation were determined in diverse compartments of the ecosystem (open field precipitation, throughfall, soil, soil solution and vegetation) on six forested catchments. TM partitioning between total and extractable content and soil solution, was studied in relation with soil parameters. PH was the most significant parameter for most TM extractability and solubility prediction. Cu and Pb solubility was also greatly influenced by complexation with organic colloids. Atmospheric inputs are moderate and regional differences reveal a stronger atmospheric influence on the North-East of France. Forest cover greatly modifies atmospheric inputs. Some fluxes (Cd, Ni, Cu and Zn) are reduced because of direct assimilation by forest canopy. Other fluxes (Pb, Cr and Sb) are increased following dry deposition accumulation on forest canopy. Elemental budget at the plot scale depend on soil type, TM solubility in soil solution and TM mobility in trees. Critical limits and loads have been evaluated and comparison with current soil solution concentration and atmospheric inputs revealed no exceedance
Geiswiller, Johann. "Application de la méthode des distributions surfaciques de charges discrètes à la modélisation d'antennes électriques en milieu plasma." Orléans, 2001. http://www.theses.fr/2001ORLE2027.
Picard, Émilie. "Étude et modélisation du transport de petites molécules dans des nanocomposites à charges lamellaires : optimisation des propriétés barrière." Lyon 1, 2007. http://www.theses.fr/2007LYO10096.
The aim of this work is to study and to improve barrier properties of nanocomposites prepared from lamellar nanofillers and two different semi-crystalline polymers. The permeability of the nanocomposites films is relates to the state of dispersion of the fillers, to the crystalline structure of the polymer matrix and to the filler / matrix interactions. In PA6-based nanocomposites, the permeability decreases are mainly due to a tortuosity effect induced by the well-dispersed inorganic layers. A quantitative description of the states of dispersion at different filler loadings allows a precise modelling of the gas transport properties. In HDPE-based nanocomposites, the increase in barrier properties is not directly related to the nanofillers dispersion state. They greatly depend on the interactions occurring between the fillers and the compatibilizers
Meghdadi, Neyshabouri Vahid. "Contribution à l'étude des charges utiles forte capacité : Modélisation de l'étage d'amplification en puissance - Méthodes de démultiplexages numériques." Limoges, 1998. http://www.theses.fr/1998LIMO0056.
Buzon, Stéphanie Lydie Emma. "Modélisation du comportement mécanique des poutres mixtes sous charges modérées : réponse élastique et comportement au cours du temps." Université Robert Schuman (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR30020.
This thesis is concerned with the composite beams composed of a girder (steel, wood,. . . ) linked to a concrete slab by any connection system. The elastic analysis accounts for the slip at the slab-girder interface and for the slab reinforcement. The time-dependent behaviour accounts for the slip at the interface. For the time-dependent behaviour of the concrete and those of the girder (if it is composed op a viscoelastic material) according the incremental formulation of the linear viscoelasticity. The proposed approach has to main advantage to express the mechanical variables at a step-time only in function of these of the previous step-time. The computation of this model is checked by means of a numerical comparison with the general integral formulation computed by other authors. The simulations of the elastic behaviour and the time-dependent one are compared to test data. The engineering mechanical variables (stresses, strains, deflections) are accurately evaluated but the slip is always overestimated
Jamei, Mehrez. "Contribution à la modélisation du comportement plastique des sols partiellement saturés pour le calcul numérique des charges limites." Grenoble 1, 1993. http://www.theses.fr/1993GRE10150.
Pham, Cong Duc. "Cartographie de charges d'espace par méthode FLIMM / Complémentarité avec les méthodes PEA et TPT." Phd thesis, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00452132.
Lefèvre, Anthony. "Contribution à la modélisation électrique, électromagnétique et thermique des transformateurs: Application à l'étude de l'échauffement sur charges non linéaires." Phd thesis, Université de Nantes, 2006. http://tel.archives-ouvertes.fr/tel-00116335.
Une première modélisation s'appuie sur une méthode analytique et axisymétrique permettant le calcul de la distribution des densités de courant dans les enroulements. Puis, après une homogénéisation des conducteurs, une méthode de résolution par éléments finis aboutit à l'obtention de la température en régime permanent. Enfin, la méthode est vérifiée sur un transformateur de type sec et de puissance modérée, associé à un banc expérimental innovant.
Un second modèle propose une nouvelle approche analytique et numérique. Tout d'abord, une méthode des éléments finis 3D (MEF) permet le calcul du champ magnétique. Ce calcul non linéaire est alors associé aux équations de circuit. Puis, une MEF thermique 3D fournie la distribution de température. Finalement, le modèle couplé est appliqué à un transformateur de distribution de petite puissance et instrumenté pour vérifier le suréchauffement engendré par des courants non sinusoïdaux.
Lefevre, Anthony. "Contribution à la modélisation électrique, électromagnétique et thermique des transformateurs : application à l'étude de l'échauffement sur charges non linéaires." Nantes, 2006. http://www.theses.fr/2006NANT2054.
The widespread use of nonlinear loads in the industry is the source of several disturbances in the electrical network. Thus the current harmonics leads to increase the losses due to proximity and skin effects in the transformer windings. Therefore, the transformers become more sensitive to overheating. In order to avoid a dielectric failure as well as a premature ageing, the hot spot temperature must not exceed the prescribed insulating value. However, for a given nonlinear load it is difficult to predict the electromagnetic and thermal state of the transformer. The main objective of this research is to characterize the harmonic behaviour of the power transformer to prevent, at the design stage, these unexpected troubles. A first work presented in this thesis deals with an analytical and axisymétric method to compute the winding current density distribution. Then, the conductor layers are homogenised and a steady state thermal finite element calculation is applied to obtain the temperature map. Finally, the effectiveness of the proposed method is verified on a medium power dry type transformer loaded by an innovative experimental installation. A second model is based on a new analytical and numerical method. First a 3D finite element method (FEM) is applied to compute the magnetic field in the free and the iron spaces. This non-linear calculation is combined with a mixed form of the electrical circuit equation. Then a 3D thermal FEM allows to show the temperature distribution in the transformer. Finally this coupling model is applied to a small power distribution transformer with embedded sensors to verify the overheating effect of non sinusoidal currents
Amiaud, Anne-Charlotte. "Modélisation du transport électronique et de l'accumulation de la charge dans les isolants en couches minces." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS004/document.
Dielectric materials can be found in numerous devices in microelectronics. They can be subjected to significant electrical stress, which impacts their lifetime. Indeed, this electrical stress can lead to dielectric breakdown or modify the component performances by charge storage. In this work, several characterization methods and physical analysis have been used in order to study the samples and identify mechanisms involved in charge transport in silicon nitride thin films. Then a simulation code has been developed to model charge transport phenomena in insulators. This model takes into account tunnel and thermal effects in the dielectric and at the dielectric-metal interfaces. The temporal and spatial evolution of physical quantities (currents, charge, electric field) in the dielectric film are calculated. Measurement results on capacitive components can be obtained thanks to simulations. This simulation tool allows testing dielectric materials according to capacitive component reliability. It may be used to define optimal properties for materials depending on applications or to assist in device design in microelectronics
Hudebine, Damien. "Reconstruction moléculaire de coupes pétrolières." Lyon, École normale supérieure (sciences), 2003. http://www.theses.fr/2003ENSL0250.
Perez, Romero Sergio Alejandro. "Approche experimentale et numérique de la fissuration réflective des chaussées : de la chaussée instrumentée au laboratoire en passant par la modélisation." Limoges, 2008. https://aurore.unilim.fr/theses/nxfile/default/8a632270-ccc9-4e1d-b0d9-864a330063c7/blobholder:0/2008LIMO4070.pdf.
In the domain of pavement maintenance, a major problem observed is the frequent incidence of reflective cracking over the top asphalted new layer. The object of this work is to determine the internal efforts in this layer in order to define the loading protocols for the reflective cracking testing machine called MEFISTO at the Laboratoire Regional d'Autun (LRA). In a first stage, the phenomenon of reflective cracking was studied on a small track in a full scale test using the Accelerated Pavement Testing (APT) machines FABAC of the LCPC. The experimental results have been compared with numerical calculations made with the CESAR-LCPC FEA software. This comparison has lead into a validation of the calculation hypothesis and into a better comprehension of the reflective cracking failure mechanism reproduced with the LCPC APT equipment. In a second stage, the FEA calculation method was used to define the loading protocols of the MEFISTO equipement
Bortoluzzi, Edson Campanhola. "Nature des constituants, propriétés chimiques et physiques des sols : modélisation des charges superficielles dans des sols sableux au Sud du Brésil." Paris, Institut national d'agronomie de Paris Grignon, 2003. http://www.theses.fr/2003INAP0003.
Azouz, Niramson. "Modélisation des flux d'ammoniac aux échelles locale et régionale dans des paysages hétérogènes : application à l’évaluation des dépassements des charges critiques." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066030/document.
Short-range atmospheric dispersion of ammonia emitted by agricultural sources and its subsequent deposition to soil and vegetation can lead to the degradation of sensitive ecosystems as well as soil acidification. Atmospheric concentrations and dry depositions rates of NH3 are generally higher near the emission source and environmental impacts on sensitive ecosystems are often largest at these locations. To better evaluate the impacts and their extent at the agricultural landscapes scale, scientific reviews of NH3 assessment methods recommended a comparison between different types of models at different spatial scales. In this context, we compared NH3 fluxes simulated by two atmospheric dispersion, transport and deposition models (CHIMERE and OPS-ST) for different theoretical and semi-real scenarios and for different grid cell sizes. The simulation results show that the averaged NH3 dry deposition over the investigated domains is comparable for grid cell sizes for which the models were designed. This implies that eulerian models with a km scale horizontal resolution can be used for studying the larger scale impact of NH3 on atmospheric composition despite an inadequate treatment of near source dry deposition, for which the models diverge. Meteorological conditions and grid cell size are the factors having the strongest effects on the results of the two models. NH3 dry deposition predictions can be used to map critical load exceedances, our results show that the detection of these exceedances near to the sources is better represented with OPS-ST than with CHIMERE, the latter showing an overestimation of the surfaces exceeding critical loads
Azouz, Niramson. "Modélisation des flux d'ammoniac aux échelles locale et régionale dans des paysages hétérogènes : application à l’évaluation des dépassements des charges critiques." Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066030.
Short-range atmospheric dispersion of ammonia emitted by agricultural sources and its subsequent deposition to soil and vegetation can lead to the degradation of sensitive ecosystems as well as soil acidification. Atmospheric concentrations and dry depositions rates of NH3 are generally higher near the emission source and environmental impacts on sensitive ecosystems are often largest at these locations. To better evaluate the impacts and their extent at the agricultural landscapes scale, scientific reviews of NH3 assessment methods recommended a comparison between different types of models at different spatial scales. In this context, we compared NH3 fluxes simulated by two atmospheric dispersion, transport and deposition models (CHIMERE and OPS-ST) for different theoretical and semi-real scenarios and for different grid cell sizes. The simulation results show that the averaged NH3 dry deposition over the investigated domains is comparable for grid cell sizes for which the models were designed. This implies that eulerian models with a km scale horizontal resolution can be used for studying the larger scale impact of NH3 on atmospheric composition despite an inadequate treatment of near source dry deposition, for which the models diverge. Meteorological conditions and grid cell size are the factors having the strongest effects on the results of the two models. NH3 dry deposition predictions can be used to map critical load exceedances, our results show that the detection of these exceedances near to the sources is better represented with OPS-ST than with CHIMERE, the latter showing an overestimation of the surfaces exceeding critical loads
Mergo, Mbeya Karrick. "Contribution à la modélisation de batteries lithium ion : optimisation des charges rapides par rapport à la réaction de dépôt de lithium métal." Thesis, Compiègne, 2021. http://www.theses.fr/2021COMP2595.
Lithium deposition reaction is a local and undesirable phenomenon within Li-ion batteries. It is widely describe in the literature as one of the major limiting phenomena of rapid Li-ion cell loading. The control ofthis reactio in real time therefore seems to be a key factor for an optmal fast charging. This is classically studied by ve complex physical models and using experimental techniques requiring invasive tests on battery. As part of th study ofthis thesis, a methodology has been established, including a simplified modelling as well as non-invasiv experimental characterizations of Li-ion, to estimate all charging currents close to the limit of the lithiu deposition reaction. Experimental studies have been conducted on a graphite/LFP cell to validate these current and this resulted in a charging protocol where the current evolves With the load state and temperature of the cel It has been observed that these currents allow the cell to be charged ultra quickly without triggering the lithiu metal deposition reaction. For a charge at 0°, the cell has been recharged in 11 minutes between 10% and 87% of the state of charge. It has been validated that the estimated currents are close to, less than 10%, the « real » lim for triggering the lithium deposition reaction. Finally, by comparing cycling With these estimated limit curren and the charge at IC, no additional aging has been observed after more than 100 cycles at 0°
Bakulu, Natungadio Florian. "Analyse et modélisation de la dynamique de jets décollés en tuyère supersonique." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2019. http://www.theses.fr/2019ESMA0020.
This thesis, conducted in collaboration with CNES and Pprime Institut, has the objective of enhancing the dynamic phenomena understanding present in supersonic rocket nozzle. These phenomena may cause lateral loads that can damage the nozzle.The study focused on an ideal nozzle geometry and 3 operating points. The work is based on the exploitation and analysis of experimental and numerical data. The experimental data come from a campaign carried out within the Pprime Institute involving measurements of wall pressure synchronized with measurements of velocity fields by PIV. In addition, a numerical part reproducing the experimental tests using high-performance numerical simulations based on hybrid RANS/LES approaches is carried out.The experimental and numerical data show a particular organization of the wall pressure fluctuations observed in some work whose origin remains unknown. The study shows that this organisation is also present in the velocity field of the jet where links with wall pressure have been established by correlation calculations. Numerical simulations show that such a coordination of the pressure field drives the lateral force dynamics. Some scenarios on the origin of this organised fluctuation are discarded by the use of reduced flow models
Grede, Audrey. "Modélisation des chocs d'origine pyrotechnique dans les structures d'Ariane5 : développement de modèles de propagation et d'outils de modélisation." Phd thesis, Ecole Centrale Paris, 2009. http://tel.archives-ouvertes.fr/tel-00453296.
Mousseau, Sébastien. "Étude du comportement structural d'un bâtiment en béton à hautes performances sous charges sismiques par essais pseudo-dynamiques et modélisation non linéaire." Thèse, Université de Sherbrooke, 2005. http://savoirs.usherbrooke.ca/handle/11143/1782.
El, Houjeyri Imane. "Expérimentation et modélisation du comportement des assemblages en bois réalisés par des tourillons en bois densifié sous des charges monotones et cycliques." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0236.
It is a question of working on multi-layered beams (or cross-laminated wood panels assembled mechanically by densified wood dowels) Traditionally, this type of beam, called laminated beam, is obtained by gluing wooden laminates. which ensures a "perfect" connection thus leading to a multi-layer beam (or Panels) whose characteristics can be obtained by homogenization. In this work, it proposed to replace the glue by the densified wood dowels to make the assemblies. The viability of beams (or panels) assembled by densified wood dowels (more ecological) is not yet fully demonstrated and therefore remains exploratory. The analysis of this type of structure (static or dynamic) must consider the fact that the connection between the wood parts is semi-rigid. therefore, it is precisely planned to characterize this type of structure experimentally and on a large scale. The main objective of the proposed thesis is to evaluate the structural response under monotonic and cyclic loads. More particularly, the response under cyclic load is obviously a key parameter for the validation of this type of assembly under seismic load. As part of this study, it is envisaged to use numerical simulation (use of Abaqus) to reduce expensive experimental tests and optimize the chosen design choices
Grédé, Audrey. "Modélisation des chocs d’origine pyrotechnique dans les structures d’Ariane5 : développement de modèles de propagation et d'outils de modélisation." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2009. http://www.theses.fr/2009ECAP0006/document.
Reliable and efficient numerical models for the pyrotechnic shock wave propagation in structures of the Ariane5 launcher are necessary for a good understanding and a predictive analysis of the payload vibration environment. More precisely, the correct modeling of the dynamic behaviour of the honeycomb sandwich shells, the main material composing the payload adaptor, is essential to control the vibration environment of the payload and the embarked electronic equipments and so to prevent them from damages caused by the shock wave propagation. The topic is obviously a multi-scale problem from both temporal and spatial points of view : short time intervals imposed by supersonic moving loads vs. large total time interval that the slowest waves need to travel throughout the adaptor ; very short wavelengths of high frequency waves, and very small size of the honeycomb cells vs. large structure dimensions. To take into account all involved space-time scales in a reliable and efficient way, the herein study is based both on the analytical and numerical qualification of the classical homogenized models of honeycomb sandwich shells for the frequency range introduced by the pyrotechnic shock wave, and on a dynamic solver based on the well-known space-time discontinuous Galerkin method, allowing the use of adaptive remeshes for the wave propagation. The classical Mindlin-Reissner’s kinematics of thick plates being inefficient to correctly represent the dynamic out-of-plane behaviour of the honeycomb sandwich plates, two kinds of its enrichment are considered : One-layered models based on an enrichment of the kinematics by adding degrees of freedom in the thickness, and multi-layered models composed of a superposition of three plates with separated material homogenisations. It has been shown theoretically and numerically that, both types of enrichment allow more precise descriptions of flexure and transverse shear modes in the high frequency range. However, the multi-layered models give much more promising results, as the important role played by the honeycomb core for the transverse shear behaviour of the whole sandwich is not “smeared” in a one-layered homogenized model. All the numerical studies were conducted with a finite element code which uses a dynamic solverbased on the time discontinuous space-time Galerkin method. The built-in numerical damping of this solver can interfere with a physical damping potentially introduced by the numerical model and results in a global damping totally unexpected. This interaction has been analysed and underlined in this work thanks to the introduction of the Rayleigh damping in the shock wave propagation models. Theoretical and numerical tools and propagating models thus developed have been validated on several academic and industrial structures. Comparison with experimental data on large size industrial structures, especially a real size payload adaptor, is performed and emphasizes the coherence of our approach and the reliability and the efficiency of the proposed propagating models
Artola, Laurent. "Étude et modélisation des mécanismes de transport et de collection de charges dédiées à la prédiction de SEE dans les technologies fortement intégrées." Toulouse, ISAE, 2011. http://www.theses.fr/2011ESAE0025.
Natural radiative environment is known to induce functional errors in electronics. Particles, such as neutrons, protons or heavy ions are known to induce these errors in electronic devices so called SEE (Single Event Effects). It's critical for industrial and space agencies to evaluate this risk. In this context, a new methodology of prediction is proposed in order to stimate the operational error rate for integrated devices boarded in space or avionic flights. Preliminary TCAD simulations lead to identify the physical mechanisms of transport and charges collection and lead to determine the critical technological parameters which impact the behaviour of the MOS transistor. These works emphasize the necessity to take into account the dynamic modeling of ambipolar diffusion velocity. Based on these works, the ADDICT model (Advanced Dynamic Diffusion Collection Transient) has been proposed. The main part of this work is focus on the validation of the transient current model by comparisons with experimental results ans TCAD simulations. In order to study the SEU and MBU events, a new upset criterion used with ADDICT leads to propose a new prediction methodology. This methodology has been compared with experimental cross sections issued from literature and tests campaign (for various SRAM memories from 0. 25 µm to 65 nm). Finally the ADDICT model has been evaluated for operational experiments. Actually, commercial SRAM memories (90 nm Cypress) has been boarded on stratospheric balloons. This last work shows the relevant operational prediction proposed by ADDICT
Lazar, Oana. "Analyse et modélisation des mécanismes de dégradation de grille des transistors à haute mobilité électronique (HEMT) de type AlGaN/GaN." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30349.
The recent introduction of wide bandgap materials revolutionizes the RF field of power modules. Due to the high-power levels for telecommunication frequency bands, GaN technologies represent nowadays a major integrated alternative which is believed to gradually replace III-V GaAs technologies (SSPA amplifiers), and even to compete with wave tubes technologies (TWTA amplifiers). Development of GaN material in the last decade is proved by the market release of several GaN versions, such as GH50 and GH25 from UMS. These batches are issued from technological versions that feature delicate mastering of the various degradation mechanisms induced by thermal, electrical or RF stress: IDQ tests, HTRB, HTOL, etc. The complexity of the involved processes (thermal, piezoelectric, ...) often makes difficult the analysis of mechanisms that caused the identified damage, and it is necessary to establish a rigorous multi-physics study in order to identify the sensitive electrical and technological parameters. The analysis associated with this work are based on cross non-invasive measurements, in transient and spectral domains. This purely metrological approach reaches its limits insofar as the crossing between non-destructive and destructive data cannot be applied to the same components, nor before/after application of a stress. Therefore, the objective of this thesis consists in giving some key indicators which can be useful when converging from these industrial and under development technologies to more robust and more efficient processes. In this way, we will be able to improve also our knowledge concerning the multitude and poorly controlled degradation kinetics. The identified technologies for technological support are the qualified or under development dies, issued from UMS: GH50 and GH25. On each of these versions, we can identify limiting mechanisms both at instant t0, and during evolution under stress. From technology maturation point of view, we can identify sensitive areas that limit operational security zones of the devices, and enable technologists to improve the technological processes. In addition, this dual input technology will allow us to implement the working methods that we have developed in this thesis. Transient techniques (non-invasive), such as I-V-T DC and pulsed measurements, will be analyzed and correlated with low frequency noise measurements (in frequency domain), on witness (virgin) components. By the means of electrical measurements, gate lag and lag drain phenomena can be identified, which are the main limiting factors for power applications and pulsed radar applications. Low frequency noise characterizations are recognized as reliable indicators for the analysis of defects in different areas (active or not) of the devices under test. The analysis and the location of these noise sources is fundamental for the next step. Then, these associated measurements and modeling techniques are used to study stressed (aged) components. On one hand, the evolution of electric linearity characteristics allows the comprehension of the stress consequences on the operational behavior of the device. On the other hand, the evolution of noise spectra allows the access to a corpuscular view of the defect that initiates the lowering of the transistor performances. These evolutions constitute a reliable database, which can be used in order to better understand the immediate and slow changes in reversible and irreversible degradation process of the devices under test: modification of the Schottky diode, presence of acceptors traps, mobile and fixed charges, slow and fast traps phenomena
Cathelin, Julien. "Modélisation du comportement mécanique des engrenages en plastique renforcé." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0029/document.
Polymer gears present several advantages: they can be used without lubricant, their meshing is silencer, resistance to corrosion is better, weight is reduced. However they have a poor heat resistance and are limited to rotation transmission. In order to improve the gears performance, glass fibre reinforcement is being increasingly used, where their lower cost and higher strength, compared to unreinforced polyamide, offer a potential increase in gear performance. Mechanical behaviour of polymers materials is very complex; it depends on time, history of displacement, temperature and for several polymers, on humidity. Moreover, an addition of fibres can make the material properties heterogeneous and anisotropic. The particular case of Polyamide 6 + 30% glass fibres which is the most common fibre reinforced plastic is studied in this work. In the first part of this work, a mould was developed to better control the material choice and moulding conditions. Using tomographic observations, investigations were done to better understand the relation between moulding conditions, gears geometry and fibres orientation. Based on these observations and with the help of mechanical characterisation, a linear rheological generalized-Kelvin model was developed to simulate the viscoelastic behavior of the polymer material. In a second part, this model taking into account temperature, humidity and rotation speed is integrated in quasi-static load sharing computation developed by the LaMCoS laboratory. In the load sharing calculus, the displacements are obtained on a large meshing covering the entire surface of the tooth. This relation integrates the viscoelastic displacement, the fibre orientation and the geometrical influence coefficients. The method permits to obtain results such as the loaded transmission error, the instantaneous meshing stiffness, the load sharing and the root tooth stress at different temperature, humidity and rotation speeds within a reasonable computation time. Investigation have shown interesting results regarding the historic of displacements which represents up to 15% of the total displacement at the tip radius, the localization of the maximal tooth root stress, which is the same than metal gears, or the influence of the thermal expansion toward transmission error. On another hand, we have highlighted the low difference between a realistic description of the fibre orientation and an homogeneous anisotropic one. The last step concerns the validation of the numerical. The measurements are carried out on a test bench developed at the LaMCoS laboratory. It provides two experimental results: the temperature of the gear during operation, and the load transmission error using optical encoders to measure the angular positions of the pinion and the gear. This one is global enough to validate the three steps of the model: geometry, kinematics and load sharing
Richler, Kevin-Davis. "Modélisation du couplage électron-vibration dans les cellules solaires organiques : une approche par champ moyen dynamique inhomogène." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY052.
In this thesis, we have developed an inhomogeneous dynamical mean-field theory (I-DMFT) that is suitable to investigate electron-phonon interactions in non-translationally invariant and/or inhomogeneous systems. The presented approach, whose only assumption is that of a local, site-dependent self-energy, recovers both the exact solution of an electron for a generic random tight-binding Hamiltonian in the non-interacting limit and the DMFT solution for the small polaron problem in translationally invariant systems. To illustrate its full apabilities, we have applied I-DMFT to study polaron formation in the presence of isolated impurities, where we have found that I-DMFT is more accurate than the inhomogeneous momentum average approximation (IMA) and gives quantitative accurate results when compared to the approximation free diagrammatic Monte Carlo calculations. We then use I-DMFT to study the effect of defects embedded on a two-dimensional surface. The computed maps of the local density of states reveal Friedel oscillations, whose periodicity is determined by the polaron mass. This can be of direct relevance for the interpretation of scanning-tunneling microscopy (STM) experiments on systems with sizable electron-lattice interactions. Next, we have focused on the interfacial electron-hole separation mechanism in prototypical organic photovoltaic donor-acceptor systems. Using I-DMFT, we present a fully quantum dynamical simulation of the charge carrier dynamics that considers the interplay of electron-vibration interactions, static-disorder, and electrostatic fields. In particular, these simulations provide the possibility to compute the charge injection rate at the donor-acceptor interface, a quantity of fundamental experimental interest, presenting one first step forward to a long-standing cumbersome challenge in OPV, thereby bridging between chemistry and physics. As a first step, we have applied the I-DMFT to a generic one-dimensional model Hamiltonian, whose parameters model the charge carrier dynamics in prototypical Phenyl- C61-butyric acid methyl ester (PCBM) or C60 acceptor systems. Our results show that dynamic potentials (related to polaron formation), when compared to random static po- tentials, can present the main detrimental lose mechanism in OPVs devices. From this perspective, organic molecules with moderate reorganization energies should be used pref- erentially in next-generation materials since increasing the electron-phonon interaction hinders the range of suitable incoming electron energies due to the fragmentation of the local density of states into narrow polaronic sub-bands. As a final step, we have applied the I-DMFT to a generic three-dimensional model Hamiltonian, whose parameters model charge splitting force fields at three-dimensional PCBM and C60 acceptor systems. These fields are sharply peaked over a narrow interphase stemming from the protrusion of small fullerene molecules into the donor domain. We then show that such fields, when dimensioned sufficiently and poled correctly, can provide an uplifting influence on the charge separation efficiency across organic interfaces. From this perspective, materials that present sufficiently and correctly poled strong electrostatic, mesoscale fields should be probed in the design of next-generation OPV devices since such fields extend the range of suitable incoming electron energies and increase the quantum yield. Overall, the easy numerical implementation of I-DMFT and its successful application in treating the charge carrier dynamics at prototypical three-dimensional donor-acceptor systems allows one to study accurately and without further difficulties problems that were previously difficult to access
Sareni, Bruno. "Méthodes d'optimisation multimodales associées à la modélisation numérique en électromagnétisme." Phd thesis, Ecole Centrale de Lyon, 1999. http://tel.archives-ouvertes.fr/tel-00139202.
BERNARDINI, Sandrine. "Modélisation des structures Métal-Oxyde-Semiconducteur (MOS) : Applications aux dispositifs mémoires." Phd thesis, Université de Provence - Aix-Marseille I, 2004. http://tel.archives-ouvertes.fr/tel-00007764.
Breton, Jean. "Modélisation thermique et simulation numérique en régime variable de parois à lame d'air insole et/ou ventilée : intégration dans un code de calcul de charges thermiques de bâtiments." Lyon, INSA, 1986. http://www.theses.fr/1986ISAL0014.
In our present work we develop detailed numerical software of the thermal behaviour of walls containing a vertical air slab and used as solar or internal gains collectors(Trombe wall, green house effect wall. . . ). The first part is devoted to a bibliographic analysis of convective behaviour of large aspect ratio cavities. In a second part we define the hypothesis and describe the numerical mode is used for each wal1 and their coupling with a detailed software of the thermal behaviour of buildings. The third part presents parametric studies of physical or technological characteristics of the walls. We use here an original criteria for the energetic performance (the Solar Gain Ratio) which enable us to show the main influence of the aeraulic and thermal couplings between the wall and the dwelling cell. Finally we propose simplified mode is which respect this last point and accept a more general description of the physical phenomena inside the walls
Galloy-Gimenez, Lucie. "Réalisation d'une cellule électroacoustique pulsée à haute résolution spatiale en vue de l'étude spatio-temporelle de la répartition de la charge d'espace dans les diélectriques spatiaux soumis à un environnement chargeant." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2516/.
Dielectric materials are frequently used in satellite structures as thermal blankets. Various aspects of the space environment can cause orbit satellite anomalies. One of these aspects is charge accumulation due to the flux of space charged particles. To get a better control of the discharge it is necessary to clarify the nature and the time evolution of position and quantity of stored space charges and to understand the dynamics of the charge transport in solid dielectrics used in outer space. Dielectrics materials for space application are typically thin, less than 50 µm. Therefore; the pulsed electro-acoustic - PEA - method, which is used to recover charges within this type of material, is no longer sufficiently precise, i. E. The spatial resolution is on the order of ten µm. We developed an electrical model of the PEA cell and we note that the piezoelectric losses and impedance matching between the different materials of the PEA cell have a significant influence on the quality of the transducer output voltage. Then, we present a high resolution PEA prototype, used to perform first ever; to our knowledge, measurements on the 50 µm thick PTFE with a special resolution of 1µm