The goal of the master thesis is the design and construction of a device for capturing video sequences of the cardiovascular system of the finger of a human hand and the subsequently design and implementation of a method of data extraction for its reconstruction into a 3D model.

Neue elektrische Antriebskonzepte ermöglichen es, eine hohe Funktionalität in einem eingeschränkten Bauraum unterzubringen. Damit steigt auch in der Landwirtschaft das Interesse an elektrischen Antrieben. Die Projektgruppe Elektrische Maschinen und Antriebe der HTW Dresden beteiligt sich mit der TU Dresden an einem Projekt, bei dem beginnend mit der elektrisch angetriebenen Dreschtrommel umfassend an einem Mähdrescher untersucht wird, wie diese Antriebe in einzelne Funktionselemente integriert werden können. Neben der Auslegung der Antriebe werden Verfahren erarbeitet, die Verluste im Motor mit hoher Genauigkeit zu berechnen. So können in Zukunft passgenaue Kühlkonzepte für diese Antriebstechnik entwickelt werden. Anforderungen gerade im Bereich der Elektromobilität fordern den Blick für neue Materialien, deren elektromagnetisches und thermisches Verhalten werden in ihrem Einfluss auf die Erwärmung untersucht. Analytische und kombinierte Berechnungsmethoden in 2D-FEM gestatten die vereinfachte Rechnung unter Berücksichtigung von Grundwelle und entstehenden Harmonischen zu qualifizieren. Verlustberechnungen aus der transienten FEM-Rechnung ermöglichen diese Verbesserung. Die Methode wird am Beispiel der elektrischen Dreschtrommel mit den berechneten Verlustverteilungen beschrieben. Neue Methoden der 3D-FEM, wie sie die Software Ansys bietet, werden für die Nutzung von Einflüssen der Wirbelstromeffekte und in Auswertung für die Segmentierung von Permanentmagneten dargestellt. Die exemplarisch gewonnenen Erkenntnisse liefern einen Beitrag für weitere Schneidwerksantriebe am Mähdrescher, aber auch darüber hinaus in Projekten mit Herstellern elektrischer Maschinen. / New concepts for electrical drives make it possible to put a high functionality into a restricted structural form. Thereby the interest in electrical drives increases also in the farming. The project team Electrical machines and drives of the HTW Dresden participates together with the TU Dresden in a project, where starting with the electrically driven threshing cylinder is comprehensively examined at a combine harvester, how these drives can be integrated into single function elements. Besides the dimensioning of the drives are developed methods to calculate losses in the engine with high precision. So custom-fit cooling concepts can be developed for this drive technology in future. Requirements just in the area of the electric mobility call looking for new materials, whose electromagnetic and thermic behavior are examined in her influence on the warming. Analytical and combined computation methods in 2D-FEM allow the simplified calculation under consideration of the fundamental wave and the arising harmonic ones. Loss calculations by means of the transient FEM calculation make possible this improvement. The method is described at the example of the electrical threshing cylinder with the calculated loss distributions. New methods of the 3D-FEM, as the software of Ansys offers, are presented for the use of influences of the eddy current effects and in evaluation for the segmentation of permanent magnets. The exemplarily got knowledge provides a contribution for further cut header drives at the combine but also furthermore in projects together with manufacturers of electrical machines.

L'objectif de cette thèse est de faciliter le diagnostic du cancer de la vessie. Durant une cystoscopie, un endoscope est introduit dans la vessie pour explorer la paroi interne de l'organe qui est visualisée sur un écran. Cependant, le faible champ de vue de l'instrument complique le diagnostic et le suivi des lésions. Cette thèse présente des algorithmes pour la création de cartes bi- et tridimensionnelles à large champ de vue à partir de vidéo-séquences cystoscopiques. En utilisant les avancées récentes dans le domaine de la minimisation d'énergies discrètes, nous proposons des fonctions coût indépendantes des transformations géométriques requises pour recaler de façon robuste et précise des paires d'images avec un faible recouvrement spatial. Ces transformations sont requises pour construire des cartes lorsque des trajectoires d'images se croisent ou se superposent. Nos algorithmes détectent automatiquement de telles trajectoires et réalisent une correction globale de la position des images dans la carte. Finalement, un algorithme de minimisation d'énergie compense les faibles discontinuités de textures restantes et atténue les fortes variations d'illuminations de la scène. Ainsi, les cartes texturées sont uniquement construites avec les meilleures informations (couleurs et textures) pouvant être extraites des données redondantes des vidéo-séquences. Les algorithmes sont évalués quantitativement et qualitativement avec des fantômes réalistes et des données cliniques. Ces tests mettent en lumière la robustesse et la précision de nos algorithmes. La cohérence visuelle des cartes obtenues dépassent celles des méthodes de cartographie de la vessie de la littérature / The aim of this thesis is to facilitate bladder cancer diagnosis. The reference clinical examination is cystoscopy, where an endoscope, inserted into the bladder, allows to visually explore the organ's internal walls on a monitor. The main restriction is the small field of view (FOV) of the instrument, which complicates lesion diagnosis, follow-up and treatment traceability.In this thesis, we propose robust and accurate algorithms to create two- and three-dimensional large FOV maps from cystoscopic video-sequences. Based on recent advances in the field of discrete energy minimization, we propose transformation-invariant cost functions, which allow to robustly register image pairs, related by large viewpoint changes, with sub-pixel accuracy. The transformations linking such image pairs, which current state-of-the-art bladder image registration techniques are unable to robustly estimate, are required to construct maps with several overlapping image trajectories. We detect such overlapping trajectories automatically and perform non-linear global map correction. Finally, the proposed energy minimization based map compositing algorithm compensates small texture misalignments and attenuates strong exposure differences. The obtained textured maps are composed by a maximum of information/quality available from the redundant data of the video-sequence. We evaluate the proposed methods both quantitatively and qualitatively on realistic phantom and clinical data sets. The results demonstrate the robustness of the algorithms, and the obtained maps outperform state-of-the-art approaches in registration accuracy and global map coherence

[Truncated abstract] Rocks, as the host to natural chains of coupled thermal, hydraulic and mechanical processes, are heterogeneous at a variety of length scales, and in their mechanical properties, as well as in the hydraulic and thermal transport properties. Rock heterogeneity affects the ultimate hydro-carbon recovery or geothermal energy production. This heterogeneity has been considered one important and difficult problem that needs to be taken into account for its effect on the coupled processes. The aim of this thesis is to investigate the effect of rock heterogeneity on multi-physical processes. A fully coupled finite element model, hereinafter referred to as a porosity-based model (PBM) was developed to characterise the thermal-hydraulic-mechanical (THM) coupling processes. The development of the PBM consists of a two-staged workflow. First, based on poromechanics, porosity, one of the inherent rock properties, was derived as a variant function of the thermal, hydraulic and mechanical effects. Then, empirical relations or experimental results, correlating porosity with the mechanical, hydraulic and thermal properties, were incorporated as the coupling effects. In the PBM, the bulk volume of the model is assumed to be changeable. The rate of the volumetric strain was derived as the difference of two parts: the first part is the change in volume per unit of volume and per unit of time (this part was traditionally considered the rate of volumetric strain); and the second is the product of the first part and the volumetric strain. The second part makes the PBM a significant advancement of the models reported in the literature. ... impact of the rock heterogeneity on the hydro-mechanical responses because of the requirement of large memory and long central processing unit (CPU) time for the 3D applications. In the 2D PBM applications, as the thermal boundary condition applied to the rock samples containing some fractures, the pore pressure is generated by the thermal gradient. Some pore pressure islands can be generated as the statistical model and the digital image model are applied to characterise the initial porosity distribution. However, by using the homogeneous model, this phenomenon cannot be produced. In the 3D PBM applications, the existing fractures become the preferential paths for the fluid flowing inside the numerical model. The numerical results show that the PBM is sufficiently reliable to account for the rock mineral distribution in the hydro-mechanical coupling processes. The applications of the statistical method and the digital image processing technique make it possible to visualise the rock heterogeneity effect on the pore pressure distribution and the heat dissipation inside the rock model. Monitoring the fluid flux demonstrates the impact of the rock heterogeneity on the fluid product, which concerns petroleum engineering. The overall fluid flux (OFF) is mostly overestimated when the rock and fluid properties are assumed to be homogeneous. The 3D PBM application is an example. As the rock is heterogeneous, the OFF by the digital core is almost the same as that by the homogeneous model (this is due to that some fractures running through the digital core become the preferential path for the fluid flow), and around 1.5 times of that by the statistical model.

Made available in DSpace on 2015-02-24T19:48:43Z (GMT). No. of bitstreams: 1 PedroXN_ate_cap4.pdf: 4119464 bytes, checksum: afcae765da030e3171f973a2422290fb (MD5) Previous issue date: 2006-05-05 / In Fazenda Bel?m oil field (Potiguar Basin, Cear? State, Brazil) occur frequently sinkholes and sudden terrain collapses associated to an unconsolidated sedimentary cap covering the Janda?ra karst. This research was carried out in order to understand the mechanisms of generation of these collapses. The main tool used was Ground Penetrating Radar (GPR). This work is developed twofold: one aspect concerns methodology improvements in GPR data processing whilst another aspect concerns the geological study of the Janda?ra karst. This second aspect was strongly supported both by the analysis of outcropping karst structures (in another regions of Potiguar Basin) and by the interpretation of radargrams from the subsurface karst in Fazenda Bel?m. It was designed and tested an adequate flux to process GPR data which was adapted from an usual flux to process seismic data. The changes were introduced to take into account important differences between GPR and Reflection Seismic methods, in particular: poor coupling between source and ground, mixed phase of the wavelet, low signal-to-noise ratio, monochannel acquisition, and high influence of wave propagation effects, notably dispersion. High frequency components of the GPR pulse suffer more pronounced effects of attenuation than low frequency components resulting in resolution losses in radargrams. In Fazenda Bel?m, there is a stronger need of an suitable flux to process GPR data because both the presence of a very high level of aerial events and the complexity of the imaged subsurface karst structures. The key point of the processing flux was an improvement in the correction of the attenuation effects on the GPR pulse based on their influence on the amplitude and phase spectra of GPR signals. In low and moderate losses dielectric media the propagated signal suffers significant changes only in its amplitude spectrum; that is, the phase spectrum of the propagated signal remains practically unaltered for the usual travel time ranges. Based on this fact, it is shown using real data that the judicious application of the well known tools of time gain and spectral balancing can efficiently correct the attenuation effects. The proposed approach can be applied in heterogeneous media and it does not require the precise knowledge of the attenuation parameters of the media. As an additional benefit, the judicious application of spectral balancing promotes a partial deconvolution of the data without changing its phase. In other words, the spectral balancing acts in a similar way to a zero phase deconvolution. In GPR data the resolution increase obtained with spectral balancing is greater than those obtained with spike and predictive deconvolutions. The evolution of the Janda?ra karst in Potiguar Basin is associated to at least three events of subaerial exposition of the carbonatic plataform during the Turonian, Santonian, and Campanian. In Fazenda Bel?m region, during the mid Miocene, the Janda?ra karst was covered by continental siliciclastic sediments. These sediments partially filled the void space associated to the dissolution structures and fractures. Therefore, the development of the karst in this region was attenuated in comparison to other places in Potiguar Basin where this karst is exposed. In Fazenda Bel?m, the generation of sinkholes and terrain collapses are controlled mainly by: (i) the presence of an unconsolidated sedimentary cap which is thick enough to cover completely the karst but with sediment volume lower than the available space associated to the dissolution structures in the karst; (ii) the existence of important structural of SW-NE and NW-SE alignments which promote a localized increase in the hydraulic connectivity allowing the channeling of underground water, thus facilitating the carbonatic dissolution; and (iii) the existence of a hydraulic barrier to the groundwater flow, associated to the A?u-4 Unity. The terrain collapse mechanisms in Fazenda Bel?m occur according to the following temporal evolution. The meteoric water infiltrates through the unconsolidated sedimentary cap and promotes its remobilization to the void space associated with the dissolution structures in Janda?ra Formation. This remobilization is initiated at the base of the sedimentary cap where the flow increases its abrasion due to a change from laminar to turbulent flow regime when the underground water flow reaches the open karst structures. The remobilized sediments progressively fill from bottom to top the void karst space. So, the void space is continuously migrated upwards ultimately reaching the surface and causing the sudden observed terrain collapses. This phenomenon is particularly active during the raining season, when the water table that normally is located in the karst may be temporarily located in the unconsolidated sedimentary cap / Esta tese apresenta resultados da pesquisa realizada no campo de petr?leo de Fazenda Bel?m-CE (Bacia Potiguar), com o objetivo de entender os mecanismos de gera??o de colapsos de terreno associados ? exist?ncia de um substrato carbon?tico intensamente fraturado e karstificado da Forma??o Janda?ra. A principal ferramenta utilizada foi o imageamento do karst soterrado com GPR (Ground Penetrating Radar). Dois eixos tem?ticos de pesquisa foram desenvolvidos: um eixo de natureza geof?sica, que consistiu no desenvolvimento de metodologias de processamento de dados de GPR, e um eixo de natureza geol?gica, que consistiu do estudo do karst Janda?ra e dos fatores condicionantes da sua evolu??o. Este segundo eixo foi fortemente apoiado no estudo de estruturas k?rsticas aflorantes e na interpreta??o de radargramas do karst soterrado. Um fluxo de processamento adequado para tratar dados de GPR ? proposto a partir da adapta??o de um fluxo usual de processamento s?smico. As principais modifica??es introduzidas est?o associadas com diferen?as fundamentais existentes entre GPR e S?smica, notadamente: pior condi??o de acoplamento entre fonte e solo, fase da wavelet (que ? mista, no GPR), grande n?vel de ru?do (inclusive a?reo), aquisi??o monocanal e maior import?ncia dos efeitos de propaga??o (principalmente dispers?o) na onda eletromagn?tica. A necessidade de um processamento adequado foi ainda mais premente em Fazenda Bel?m devido ? forte presen?a de ru?do a?reo, por se tratar de uma ?rea industrial, e grande complexidade das fei??es k?rsticas soterradas. A etapa chave do fluxo de processamento ? a corre??o dos efeitos de propaga??o. Em meios diel?tricos de perda baixa a moderada, verificou-se que a propaga??o do pulso de GPR impacta fortemente o seu espectro de amplitude, mas provoca muito pouca altera??o no seu espectro de fase. P?de-se assim corrigir os efeitos da propaga??o com uma aplica??o judiciosa de ganhos e balanceamento espectral. Os ganhos foram utilizados para recuperar a perda de amplitude e o balanceamento espectral, para recuperar as componentes da faixa superior de freq??ncia, que s?o mais fortemente afetadas pelos efeitos da propaga??o. Apesar da n?o estacionaridade do sinal do GPR, o balanceamento espectral promove um aumento de resolu??o, o que qualifica esta t?cnica como um bom substituto dos algoritmos de deconvolu??o, garantindo repetitividade e independ?ncia do meio geol?gico. A karstifica??o da plataforma carbon?tica Janda?ra est? associada a, pelo menos, tr?s eventos de exposi??o sub-a?rea relacionadas ?s discord?ncias do Turoniano, Santoniano e Campaniano. Em Fazenda Bel?m, a partir do Mioceno M?dio, o karst Janda?ra foi soterrado por sedimentos silicicl?sticos continentais. Este soterramento preencheu parte das cavidades de dissolu??o e fraturas e, assim, o desenvolvimento do processo de karstifica??o foi bastante atenuado, em compara??o com outros locais da Bacia Potiguar, onde o karst Janda?ra est? exposto. Nas condi??es vigentes em Fazenda Bel?m, identificou-se que os principais fatores condicionantes do surgimento das dolinas e do colapso de terreno s?o: (i) exist?ncia de uma cobertura inconsolidada espessa o suficiente para encobrir o calc?rio, por?m delgada o suficiente para que o seu volume possa ser acomodado nos espa?os vazios dessas estruturas; (ii) ocorr?ncia da interse??o de lineamentos estruturais SW-NE e NW-SE, que promovem um aumento localizado da condutividade hidr?ulica e condicionam a canaliza??o do fluxo hidr?ulico subterr?neo, facilitando a dissolu??o dos carbonatos; e (iii) exist?ncia de uma barreira hidr?ulica vertical, associada ? Unidade A?u-4, que condiciona a circula??o da ?gua subterr?nea a ser predominantemente lateral. Os colapsos de terreno em Fazenda Bel?m seguem o seguinte processo de evolu??o temporal. O fluxo de ?gua se infiltra atrav?s da cobertura sedimentar inconsolidada e promove sua mobiliza??o para o espa?o vazio das estruturas de dissolu??o na Forma??o Janda?ra. Este efeito ? iniciado na base da cobertura sedimentar, onde o fluxo aumenta o seu poder de abras?o, devido ? mudan?a brusca do regime laminar para o regime turbulento, ao entrar no karst. O material remobilizado vai preenchendo, as cavidades intra-acamamento e geram espa?o, de forma remontante, na cobertura sedimentar acima situada, que vai se afinando at? o ponto de colapso, quando ent?o ocorrem as dolinas. Este fen?meno ? especialmente ativo durante a esta??o chuvosa, quando o n?vel est?tico da ?gua, que normalmente est? situado dentro do calc?rio, pode estar temporariamente localizado dentro da cobertura sedimentar

Through our whole work we study the XY model with all its entirety, a particular spin model where spins are confined in a plane. We try to bring out a good understanding of this model with all different types of phases and phase transition, it undergoes in critical situations. We conceive of these external conditions from very different physical models like High Tc Superconductor, Ultracold atoms in optical lattice which are in focus of recent research. Firstly we model high Tc Superconductors with very simple 2D XY model to get an idea about the diamagnetic response exhibited by these materials when kept in a external magnetic field. This modeling is reasonable because most of the physics of cuprate High Tc Superconductors are governed by their 2D copper oxide planes which insists us to consider 2D models. Later we shifted to a more realistic 3D anisotropic XY model , as the coupling between cuprates plane may have a considerable role in devising physics of those materials. We particularly focus on the 2D to 3D crossover effect on magnetisation showed by these models, with keeping an eye on how all these can be relate to the experimentally acquired magnetisation profile of High Tc Supercondutors. On the second project we investigate on the phase diagram of a fully frustrated 2-leg ladder Bose Hubbard model. After mapping it properly to a classical model, a bi-layer Fully Frustrated XY model on square lattice, we found that the frustration leads to the emergence of a new phase "Chiral Mott insulator(CMI)" sandwiched between "Chiral Superfluid(CSF)" and "regular Mott insulator(MI)" phase. We divide the whole report into four parts. The first chapter is basically contain-ing introductory part comprising the motivation. In the second chapter we discuss various types of phases and phase transitions of the 2D & 3D XY models. We try to address their critical behaviors. In the third chapter and onwards we consider our model in external magnetic field and observe magnetisation in these systems. Here we specially focus on 2D to 3D crossover effect on magtisation measurement. Lastly in the fourth chapter we bring out a correspondence of XY model with the 2 leg ladder fully frustrated Bose Hubbard Model. There we report the emergence of a new phase, Chiral Mott Insulator(CMI) due to frustration in system.

No description available.

L'automobile nécessite l'utilisation d'échangeurs thermiques permettant d'assurer au moteur des conditions de fonctionnement en température acceptables (autour de 90°C). La fiabilité de ces échangeurs ne peut être négligée car ils peuvent être à l'origine de complications mécaniques importantes en cas de dysfonctionnement. La maîtrise des divers modes d'endommagement des échangeurs thermiques liés aux conditions d’utilisation devient dès lors un enjeu incontestable pour les industriels en charge de leur production, tant du point de vue matériaux, que du comportement général de la structure en service (influence du procédé d'assemblage, design,...). Les échangeurs thermiques présentent aujourd’hui une sensibilité accrue aux sollicitations thermomécaniques cycliques induites en service, du fait, essentiellement, d’une constante diminution des épaisseurs des composants. Celle-ci est responsable d’une augmentation significative des contraintes internes pour des conditions en service identiques, pouvant avoir pour conséquence directe et irréversible la rupture d’un tube, témoin d’une incompatibilité matière/design/process. Deux configurations matières industrielles ont ici été étudiées. Il s’agit de structures tri-couches colaminées de type tube, constituées respectivement de deux et trois alliages d’aluminium distincts (4xxx/3xxx/4xxx ou 4xxx/3xxx/7xxx), pour une épaisseur totale de 270µm. Ces dernières ont été développées pour permettre l’utilisation du procédé de brasage comme procédé d’assemblage (alliage 4xxx). Toutefois, une telle architecture, combinée à un procédé thermique d’assemblage sévère (600°C), est responsable d’une modification profonde de la microstructure avec l’apparition de structures de solidification, responsables entre autres de nombreuses irrégularités de surface (appelées Gouttes de Placage Résiduelles - GPR) ainsi que d’importants gradients de propriétés mécaniques dans l’épaisseur. Ces travaux de recherche s’appuient sur une approche expérimentale et numérique développée pour étudier les mécanismes d'endommagement en fatigue relatifs à de telles structures fines hétérogènes. Associant diverses techniques expérimentales telles que la corrélation d’images numériques (2D-3D) ou la tomographie à rayons X (de laboratoire ou à l’ESRF), elle permet une analyse précise des mécanismes d’amorçage et de propagation des fissures de fatigue (sur éprouvette de fatigue classique ou de type échangeur thermique). Le rôle des différents placages dans chacune des phases de l’endommagement a ainsi été mis en évidence (4xxx : amorçage, 7xxx : propagation des fissures). Des simulations par la méthode des éléments finis nous ont permis de compléter ces observations en proposant une quantification précise de l’influence de l’état de surface (GPR) sur la tenue en fatigue des éprouvettes testées. Enfin, des essais de fatigue réalisés directement sur échangeurs thermiques ont permis de corroborer les résultats obtenus sur éprouvettes modèles. / The automotive industry, like many other industrial fields, requires the use of heat thermal exchangers to allow optimal thermal service conditions of the engine (around 90°C for a car engine). The exchangers’ reliability has to be guaranteed to avoid a decrease of the engine efficiency or detrimental mechanical damage resulting from too high service temperatures. It is therefore necessary to control the different damage modes of such thermal heat exchangers according to the conditions of use. Thanks to their good thermal, corrosion and mechanical properties, aluminium alloys have steadily replaced copper alloys and brass for manufacturing heat exchangers in cars or trucks. Such components have been constantly optimized in terms of exchange surface area and, nowadays, this has led to Al components in heat exchangers with a typical thickness of the order of 0.2 to 1.5 mm. With such small thicknesses, the load levels experienced by heat exchangers components has drastically increased leading to an important research effort in order to improve the resistance to damage development during service life. Two industrial materials made of 3 co-rolled aluminium alloys (total thickness 0.27 mm) have been studied. In spite of their small thickness, the materials exhibit a composite structure comprising a core material (3xxx alloy) and 2 clads (4xxx and/or 7xxx alloys according to material configuration: 4xxx/3xxx/4xxx or 4xxx/3xxx/7xxx). The lower melting point 4xxx alloy is used for producing the heat exchanger assembly during a brazing process while the 7xxx alloy improves internal corrosion resistance. Such complex architecture, combined to the severe brazing thermal treatment, leads to important microstructural modifications, mainly characterized by the formation of brazing joints or Clad Solidification Drops (CSD) on the surface. Both of them are responsible for significant gradients of the mechanical properties on the thickness. The present study is based on an original experimental and numerical approach developed to characterise the different fatigue damage mechanisms operating in such thin heterogeneous structures. Digital image correlation (2D-3D) and X-rays tomography (at different resolutions) have been used to analyze the crack initiation and propagation mechanisms, highlighting the impact of each clad on each damage step. While the 4xxx clad corresponds to preferential crack initiation zones, the 7xxx clad seems to affect significantly the crack propagation phase. Finite Elements simulations have been carried out to complete these experimental observations, putting forward an accurate quantification of the surface state influence (through the CSD). All the different results and observations made on fatigue samples with a simplified geometry have been finally confirmed by fatigue tests on thermal exchanger configurations.

Cette thèse étudie divers aspects de la fiabilité des mémoires, notamment les tests en endurance et les tenues en rétention sur des mémoires Flash, en architectures NOR et NAND. Nous abordons différentes méthodes de programmation existantes dans la littérature, à savoir l'utilisation de signaux très courts et un algorithme de programmation intelligent, que nous avons appliquées sur nos cellules mémoires afin de réduire la dégradation qu'elles subissent lors des phases successives de programmation /effacement. Les améliorations observées n'étant pas significatives, nous n'avons pas choisi d'utiliser de tels signaux dans la suite de notre étude. Nous présentons également une théorie des signaux optimisés qui n'a pas été approfondie ici mais que nous avons étudiée dans une étude préalable à cette thèse. Nous présentons ensuite une modélisation des pertes de charges en rétention à partir d'équations simples de types Fowler-Nordheim et Poole-Frenkel qui se superposent et respectivement prépondérantes à des temps de rétention élevés (t>200h) et courts (t<200h). Nous proposons enfin une étude des perturbations intervenant dans une matrice mémoire, à la fois du point de vue des tensions électriques appliquées sur les cellules mais aussi du point de vue des capacités de couplages parasites. Nous avons dans un premier temps évalué les valeurs de perturbation de grille sur des cellules mémoires Flash en architecture NOR puis NAND avant de traiter des capacités parasites entre cellules dans une matrice. Nous avons été amenés à étudier ces capacités dans la cadre de l'étude des dégradations excessives des cellules inhibées lors de tests en endurance pour certaines conditions process non-optimisées. Nous avons pour cela développé une simulation TCAD bidimensionnelle à partir des étapes process réelles que nous avons ensuite calibrée sur des mesures sur silicium. Enfin cette simulation a été complétée par une prise en compte des capacités parasites de couplage, extraites sur une simulation tridimensionnelle d'une matrice 3x3 de cellules mémoires. Les valeurs de ces capacités ont été validées par des mesures sur des structures de test spécifiques et par calcul géométrique. Notre simulation bidimensionnelle émule donc un comportement tridimensionnel tout en restant dans une rapidité de calcul liée à une simulation 2D. Nous avons ainsi pu développer des simulations électriques permettant de visualiser le phénomène d'inhibition des cellules, tout au long de l'application des diverses polarisations sur la structure.

Nous nous intéresserons d'abord aux équations stochastiques de Navier-Stokes bidimensionnelles (NS), de Ginzburg-Landau Complexes (CGL) et de Schrödinger non-linéaires (NLS) munies d'un bruit blanc en temps et régulier pour la variable spatiale. En nous appuyant sur des méthodes de couplages, nous établirons le caractère exponentiellement (resp polynomialement) mélangeant de NS et CGL (resp NLS) lorseque le bruit recouvre un nombre suffisant de bas modes. Deux des innovations majeures de ces résultats sont le fait que l'on s'autorise à traiter des équations non-dissipatives telles que NLS et que l'on considère des bruits non additifs.<br />Dans un deuxième temps, nous considérerons les équations de Navier-Stokes stochastiques tridimensionnelles (NS3D). Nous établirons la régularité Hp et Gevrey des solutions stationnaires de NS3D et nous en déduirons des informations sur l'échelle de dissipation de Kolmogorov (K41). Puis, nous établirons le caractère exponentiellement mélangeant des solutions de NS3D lorsque le bruit est à la fois suffisament régulier et non-dégénéré.