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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
401

Tvorba a estimace modelu malé vodní elektrárny v programu PSCAD / Creation and estimation of small hydro power plant model in PSCAD

Razyapova, Aygul Unknown Date (has links)
This thesis focused on creating a model of a small hydropower plant model (SHPP) and a part of the electricity network in the simulation software "PSCAD" (basing on real sources). The model will be specified on the basis of the data obtained from the measurements to correspond with the real equipment.
402

SMÅSKALIG VATTENKRAFT OCH FLEXIBILITET I ELSYSTEMET : En kartläggning av förväntningarna på den småskaliga vattenkraftens potential att bidra med flexibilitet.

Andersson, Simon, Callin, Veronika January 2019 (has links)
No description available.
403

Bubble curtains with vertical tubes : A way to deter fish from hydro power intakes

Molin, Gustav January 2019 (has links)
This project was performed on assigment of Vattenfall R&D in Älvkarleby. The project was a first step in evaluating whether bubble curtains with vertical tubes could be suitable for diverting fish from hydro power intakes into fish passages. To determine this, prototypes were constructed, where one was tested in still water and one in running water. The tests in still water were carried out in a large cylindrical tank and the tests in running water were carried out in Kungsr¨annan in ¨Alvkarleby. A number of test variables were developed to be able to vary the tests. These test variables were hole size, number of holes, tube center-to-center distance, air flow and water velocity. The tests were carried out without fish, but a number of indicators were developed to be able to compare and evaluate the tests. For the tests in still water, these indicators were the width of the bubble curtain created by a single tube and the horizontal movement of the air bubbles, to determine whether the hydrostatic pressure from the surrounding water had any effect on the appearance of the bubble curtain. For the tests in running water, the indicators were the bubble curtain density, the curvature of the tubes and the movement of the tubes. All experiments were documented using cameras and the results were then obtained through image processing in the software MATLAB. The results showed that the width of the bubble curtain created by a single tube varied between 12 and 34 cm for pressures between 0.5 and 2.0 bar. It was concluded that the hydrostatic pressure was of minimal significance for the appearance of the bubble curtain, at least for depths up to 1.95 m. For the tests in running water, the air flow rate and tube center-to-center distance was of the greatest importance for the bubble curtain density. The curvature of the tubes were most affected by the size of the holes and the movement of the tubes were most affected by the number of holes. / Detta projekt utfördes på uppdrag av Vattenfall R&D i Älvkarleby. Projektet var ett första steg i att utvärdera om bubbelridåer med vertikala slangar skulle kunna lämpa sig för att avleda fisk från vattenkraftverk vidare mot fiskpassager. För att avgöra detta konstruerades prototyper, där en testades i stilla vatten och en i rinnande vatten. Testerna i stilla vatten utfördes i en stor cylindrisk tank och testerna i rinnande vatten utfördes i Kungsrännan i Älvkarleby. Ett antal testvariabler togs fram för att kunna variera testerna. Dessa testvariabler var hålstorlek, antal hål, avstånd mellan slangarnas centrum, luftflöde samt vattenhastighet. Testerna gjordes utan fisk, men ett antal indikatorer togs fram för att kunna jämföra och utvärdera testerna. För testerna i stilla vatten var dessa indikatorer bubbelridåns bredd skapad av en enskild slang samt luftbubblornas horisontella förflyttning, för att avgöra om det hydrostatiska trycket från omgivande vattnet hade någon effekt på bubbelridåns utseende. För testerna i rinnande vatten var indikatorerna bubbelridåns täthet, slangens krökning samt slangens rörelser. Alla experiment dokumenterades med hjälp av kameror och resultaten togs sedan fram genom bildhantering i programvaran MATLAB. Resultaten visade att bubbelridåns bredd skapad av en enskild slang varierade mellan 12 och 34 cm för tryck mellan 0,5 och 2,0 bar. Det bedömdes att det hydrostatiska trycket var av minimal betydelse för bubbelridåns utseende, åtminstone för djup upp till 1,95 m. För testerna i rinnande vatten visade resultaten att luftflödet och avståndet mellan slangarnas centrum var av störst betydelse förr bubbelridåns täthet. Slangens krökning påverkades mest av hålens storlek och slangens rörelser påverkades mest av antalet hål.
404

Síntese e caracterização de hidro-esponjas de polímeros condutores / Synhesis and caracterization of conducting polymers hydro-sponges

Antonio, Jadielson Lucas da Silva 08 July 2016 (has links)
Esta tese está voltada ao estudo da síntese e caracterização de hidro-esponjas de polímeros condutores estruturados sob a ação do agente molde de alaranjado de metila. A síntese destas hidro-esponjas foi realizada tanto quimicamente quanto eletroquimicamente. Na síntese química, destacam-se as hidro-esponjas de polipirrol, onde os estudos de eletrointumescimento realizados em meio aquoso, tanto a nível macroscópico (via variação de volume) quanto a nível molecular (via FTIR-ATR), mostraram que o material se comporta como um hidrogel apresentando alta capacidade de sofrer uma expansão de volume (um aumento de até 40%) e absorver grandes quantidades de água. No que se refere à síntese eletroquímica, destacam-se os filmes finos de hidro-esponja de polipirrol e de polianilina na forma tubular. Diferenças morfológicas foram analisadas de acordo com a mudança de parâmetros de síntese. Para os filmes de polipirrol, foi realizado um estudo sobre o crescimento da estrutura tridimensional de hidro-esponja via imagens AFM, onde foi observado um aumento significativo nas propriedades eletroquímicas com o aumento da estrutura esponjosa do polipirrol, mostrando grande atividade para aplicação em um sistema supercapacitivo (1200 F.g-1). Para os filmes de polianilina, foi realizado um estudo morfológico, eletroquímico e espectroscópico identificando as mudanças de propriedades provocadas pela nanoestruturação do material. Foi observado que a forma tubular da polianilina provoca uma mudança conformacional na cadeia polimérica refletindo nas propriedades eletroquímicas, principalmente devido ao aumento na população de transportadores de cargas. / The present work is focused on the study of the synthesis and characterization of conducting polymeric hydro-sponges structured by using methyl orange template. The syntheses of the hydro-sponges were performed by both chemical and electrochemical methods. Electro-swelling studies performed were with Polypyrrole hydro-sponges chemically synthezised, at macroscopic level (by volume change) and molecular level (by FTIR-ATR analysis) showing that the material behaves as a hydrogel presenting high ability to undergo large volume changes (until 40%) and to absorb high amounts of water. Regarding the electrochemical synthesis, the hydro-sponges thin films of polypyrrole and polyaniline of nanotubular shape were prepared. Morphological differences were analyzed according to the change in the synthesis parameters. For the polypyrrole films, a study of the growth of the three-dimensional structure was performed by using AFM analysis. A significant increase in the electrochemical properties with the increase of the spongy structure of polypyrrole was observed, leading to high electroactivity opening the possibility to be applied in supercapacitors (1220 F g-1). For the polyaniline films, a morphological, electrochemical and spectroscopic study was performed identifying the change of properties caused by the nanostructuring of the material. It was noted that the tubular shape of the polyaniline causes a conformational change in the polymer chain which reflects in the electrochemical properties, mainly due to the increase in the population of the charge carriers.
405

Gestion Optimale d’une installation hybride au Vietnam / Optimal Management of a hybrid installation in Vietnam

Pham, Duy An 11 July 2018 (has links)
Le Vietnam est un pays en voie d’industrialisation rapide ce qui engendre une croissance élevée des besoins énergétiques. La consommation énergétique du Vietnam est en augmentation mais pas de façon égale dans tout le pays. En effet, 66.9% de la population du Vietnam vit en zone rurale en 2014. Une grande partie de la population vit encore pauvrement dans des sites isolés avec des accès très restreint aux énergies. Le Vietnam Master Power Plan VII (2011) indique que 759.986 habitations n’ont pas accès à l’électricité.Cependant, le Vietnam est un pays qui possède un grand potentiel en énergie renouvelable (l’énergie solaire, l’énergie éolienne, l’énergie hydroélectrique, l’énergie Biomasse). Le Vietnam a élaboré une stratégie de développement des énergies renouvelables, afin de mobiliser toutes les ressources pour réduire la dépendance aux combustibles fossiles. Les sites isolés se situent principalement au Nord-Ouest du Vietnam, près de la frontière avec le Laos et la Chine, où il existe un grand potentiel d’énergie hydraulique et/ou solaire. Il faut quand même signaler que ces énergies sont souvent saisonnières et, par exemple, une microcentrale hydroélectrique ne peut pas satisfaire la demande en énergie électrique lors de la saison sèche. Donc, un système utilisant deux sources d’énergies renouvelables (panneaux photovoltaïques et microcentrale hydroélectrique) est l’une des solutions optimales pour alimenter en électricité un site isolé au Vietnam. L’objectif de cette thèse est la gestion optimale de l’électricité renouvelable d'un tel système.Afin de satisfaire à une utilisation maximale, le principe de suivi du point maximum (ou Maximum Power Point Tracking – MPPT) est mis en application. Pour la chaine de conversion photovoltaïque, un contrôleur flou à une entrée est proposé afin de suivre le point de puissance maximale du panneau solaire.Pour la chaine de conversion hydroélectrique, une turbine Pelton couplée à un générateur synchrone à rotor bobiné permet d’alimenter en électricité une charge triphasée. Une plateforme d'essais est réalisée dans le laboratoire CReSTIC, IUT de Troyes pour effectuer une validation expérimentale du système de régulation d’une Microcentrale hydroélectrique.Pour la réalisation d’un système de production d’électricité hybride, un superviseur flou est conçu pour obtenir un comportement optimal du système. Après, une étude sur les avantages et inconvénients de ce type de systèmes hybrides pour un site isolé a été effectuée (amélioration de la formation des adultes, augmentation du temps de travail pendant la nuit, réduction du coût du carburant).Ce travail contribue à la connaissance d'une gestion optimale des énergies renouvelables pour site isolé en révélant les avantages et les qualités de l’utilisation des ressources d’énergie renouvelables au gouvernement et à d’autres investisseurs locaux ou internationaux au Vietnam. / As a rapidly industrializing country, the economy of Vietnam's has become very energy intensive. Thought, 66.9% of Vietnam's population lives in rural area in 2014. Many people still live in remote farming areas that are stricken with poverty. The Vietnam Master Power Plan VII (2011) indicates that still 818,947 households are not connected to the national grid, and 759,986 households do not have any access to electricity.Vietnam has high potential on renewable energy resources (Wind, Solar, Hydro, Biomass, and Geothermal). Using hybrid renewable energy system is considered to be one of the most feasible options to bring electricity to local people to improve life quality. The off-grid communities in Vietnam are located mainly in the north-west of Vietnam, near the border with Laos and China, where exist a great potential on Hydro power and/or solar power. A micro hydro power plant cannot satisfy the load demand, especially in dry season. Therefore, additional energy sources such as PV arrays have been suggested to complement power efficiency. Thus, this working discusses the pre-feasibility for small hybrid power generation system consisting of a PV generating unit with storage and a micro hydro generation unit for off-grid areas in Vietnam.The objective of this thesis is to optimize the production of renewable electricity for this type of small hybrid power generation system. For the photovoltaic conversion system, a one input fuzzy logic controller for maximum power point tracking is designed. For the Micro-hydro power plants (MHPP), a Pelton turbine is coupled to a would rotor synchronous generator to supply electricity for a three phase load. To keep the MHPP frequency and voltage outputs constant (50 Hz, 230 V) in spite of changing user loads, the controller is necessary. The experimental results of MHPP frequency and voltages control show the ability of our controller. For the realization of small hybrid power generation, a fuzzy supervisor is adapted to obtain an optimal behavior of the system. Finally, a study on the advantages of this type of hybrid system is carried out (improvement of adult training, increased night working hours, and reduction fuel costs). This thesis contributes to the knowledge of Renewable Energy (RE) by revealing the suitable usability and prospects of RE resources to the government and other local or international investors in Vietnam.
406

Síntese e caracterização de hidro-esponjas de polímeros condutores / Synhesis and caracterization of conducting polymers hydro-sponges

Jadielson Lucas da Silva Antonio 08 July 2016 (has links)
Esta tese está voltada ao estudo da síntese e caracterização de hidro-esponjas de polímeros condutores estruturados sob a ação do agente molde de alaranjado de metila. A síntese destas hidro-esponjas foi realizada tanto quimicamente quanto eletroquimicamente. Na síntese química, destacam-se as hidro-esponjas de polipirrol, onde os estudos de eletrointumescimento realizados em meio aquoso, tanto a nível macroscópico (via variação de volume) quanto a nível molecular (via FTIR-ATR), mostraram que o material se comporta como um hidrogel apresentando alta capacidade de sofrer uma expansão de volume (um aumento de até 40%) e absorver grandes quantidades de água. No que se refere à síntese eletroquímica, destacam-se os filmes finos de hidro-esponja de polipirrol e de polianilina na forma tubular. Diferenças morfológicas foram analisadas de acordo com a mudança de parâmetros de síntese. Para os filmes de polipirrol, foi realizado um estudo sobre o crescimento da estrutura tridimensional de hidro-esponja via imagens AFM, onde foi observado um aumento significativo nas propriedades eletroquímicas com o aumento da estrutura esponjosa do polipirrol, mostrando grande atividade para aplicação em um sistema supercapacitivo (1200 F.g-1). Para os filmes de polianilina, foi realizado um estudo morfológico, eletroquímico e espectroscópico identificando as mudanças de propriedades provocadas pela nanoestruturação do material. Foi observado que a forma tubular da polianilina provoca uma mudança conformacional na cadeia polimérica refletindo nas propriedades eletroquímicas, principalmente devido ao aumento na população de transportadores de cargas. / The present work is focused on the study of the synthesis and characterization of conducting polymeric hydro-sponges structured by using methyl orange template. The syntheses of the hydro-sponges were performed by both chemical and electrochemical methods. Electro-swelling studies performed were with Polypyrrole hydro-sponges chemically synthezised, at macroscopic level (by volume change) and molecular level (by FTIR-ATR analysis) showing that the material behaves as a hydrogel presenting high ability to undergo large volume changes (until 40%) and to absorb high amounts of water. Regarding the electrochemical synthesis, the hydro-sponges thin films of polypyrrole and polyaniline of nanotubular shape were prepared. Morphological differences were analyzed according to the change in the synthesis parameters. For the polypyrrole films, a study of the growth of the three-dimensional structure was performed by using AFM analysis. A significant increase in the electrochemical properties with the increase of the spongy structure of polypyrrole was observed, leading to high electroactivity opening the possibility to be applied in supercapacitors (1220 F g-1). For the polyaniline films, a morphological, electrochemical and spectroscopic study was performed identifying the change of properties caused by the nanostructuring of the material. It was noted that the tubular shape of the polyaniline causes a conformational change in the polymer chain which reflects in the electrochemical properties, mainly due to the increase in the population of the charge carriers.
407

Caracterização microestrutural e mecânica de juntas soldadas com aço inoxidável duplex UNS S31803 pelo processo Friction Hydro Pillar Processing (FHPP) e Friction Taper Stitch Welding (FTSW)

Figueiredo, Arlan Pacheco January 2017 (has links)
Aços inoxidáveis duplex (AID) são materiais amplamente utilizados para uma grande variedade de aplicações desde a indústria química, de alimentos, petroquímica, naval, farmacêutica, energia nuclear e em muitos outros campos devido à combinação de suas excelentes propriedades mecânicas e de resistência à corrosão. Particularmente na indústria petroquímica, os aços AID’s são muito utilizados como materiais estruturais para a construção de gasodutos que transportam altos volumes de CO2 e na confecção das camadas internas dos tubos flexíveis (oleodutos offshore), utilizadas na produção de óleo. A soldagem a arco dos AID’s pode acarretar, dependendo das taxas de resfriamento envolvidas, a formação de precipitados de segunda fase que degradam suas propriedades mecânicas. Um processo alternativo para evitar o problema de precipitação de fases indesejáveis é a utilização do processo de soldagem/reparo por fricção com pino consumível (SFPC). O objetivo do presente trabalho é a caracterização metalúrgica e mecânica de juntas de solda de aço inoxidável duplex UNS S31803 obtidas através dos processos SFPC e de soldagem de costura por fricção (SCF). Na soldagem SCF, o objetivo do estudo foi a verificação da influência do passo de soldagem na formação e alteração das estruturas e nas propriedades mecânicas. Os resultados dos ensaios foram comparados com as propriedades obtidas do material base (MB) “como recebido”. A partir das juntas soldadas obtidas por fricção, foram extraídos corpos de prova para ensaios de microtração e Charpy para avaliação da resistência mecânica e da resistência ao impacto. Análises da microestrutura em microscopia ótica (MO) e perfis de microdurezas ao longo da região de solda também foram realizadas. Verificou-se que os processos de soldagem SFPC e SCF provocam um intenso refinamento de grão na zona de mistura (região da interface entre material do pino e da base), modificando a estrutura lamelar de grãos alongados da matriz ferrítica/austenítica, ocasionado por uma ação conjunta de aquecimento e deformação plástica oriunda do processo de solda por fricção. Os resultados dos ensaios de microtração indicam que as juntas soldadas aumentaram sua resistência mecânica com relação ao material base, fato que se deve ao aumento da quantidade da ferrita na zona termomecanicamente afetada (ZTMA), à formação de nitretos de cromo no centro dos grãos ferríticos e ao refino de grão. O aumento da quantidade de ferrita na ZTMA ocorre devido às altas taxas de resfriamento envolvidas no processo de soldagem e verificados por análise térmica. As elevadas taxas de resfriamento dificultam a difusão do nitrogênio que tem um importante papel no equilíbrio de fases da estrutura duplex (ferrita-austenita), na soldagem. O nitrogênio aprisionado no interior do grão ferrítico produz nitretos de cromo deixando de agir como elemento gamagênico aumentando a quantidade da fase ferrita. As juntas soldadas verificadas apresentaram tenacidade aceitável de acordo com o exigido pela norma ASTM A923. / Duplex stainless steels (DSS) are materials widely used for a variety of applications from the chemical, food, petrochemical, marine, pharmaceutical, nuclear industry and other fields due to the combination of their excellent mechanical properties and corrosion resistance. Particularly in the petrochemical industry, the DSS’s steels are extensively used as structural materials for the construction of gas pipelines that carry high volumes of CO2 and making the inner layers of flexible pipes (pipelines offshore) used in offshore oil production. The arc welding of DSS's can lead, depending on cooling rates involved, the formation of second phase precipitates which degrade their mechanical properties. An alternative method to avoid the problem of precipitation of unwanted phase is to use the welding process Friction Hydro Pillar Processing (FHPP). The aim of this work is the metallurgical and mechanical characterization of joints welds of UNS S31803 duplex stainless steel obtained through FHPP processes and Friction Taper Stitch Welding (FTSW). In FTSW welding, the objective of the study was to verify the influence of the welding step on the formation and alteration of structures and mechanical properties. The test results were compared with the properties of the obtained base material "as received". From the welds joints obtained by friction welding, specimens for microtensile testing and charpy were extracted to evaluate the mechanical strength and toughness. Microstructural analysis in optical microscopy (OM) and scanning electron microscopy (SEM) and microhardness profiles along the weld region were also performed. It was found that the welding process FHPP and FTSW causes an intense grain refinement in bonding zone, modifying the lamellar structure of elongate grains of matrix ferritic/austenitic, caused by action of heating and plastic deformation arising from the welding process by friction. The results of the microtensile tests indicate that the welded joints increased their mechanical resistance with respect to the base material, due to the increase in the amount of the ferrite in the thermomechanically affected zone (ZTMA), the formation of chromium nitrides in the center of ferritic grains and grain refining. The increase in the amount of ferrite in the ZTMA occurs due to the high cooling rates involved in the welding process and verified by thermal analysis. The high cooling rates difficult the nitrogen diffusion, which plays an important role in the phase equilibrium of the duplex structure (ferrite-austenite) in welding. The nitrogen trapped inside the ferritic grain produces chromium nitrides ceasing to act as gamogenic element by increasing the amount of the ferrite phase. The welds joints verified also had acceptable ductility and toughness according required by standard ASTM A923.
408

Etude intégrée de la dynamique des flux hydrosédimentaires dans le bas cours du fleuve Orénoque (Venezuela) par mesures in-situ et télédétection / Integrated study of the dynamics of hydro-sedimentary flows in the Lower Orinoco (Venezuela) using in-situ measurements and Remote Sensing

Yépez Figueroa, Santiago Paul 18 June 2018 (has links)
L'objectif principal de cette thèse est d'étudier la dynamique des flux hydrosédimentaires dans le bas cours de l'Orénoque à partir de la mise en œuvre de diverses techniques qui combinent directement la mesure des données in situ et la modélisation par séries chronologiques d'images satellites. Cette thèse aborde pour la première fois trois méthodologies complémentaires pour analyser les flux hydrosédimentaires dans les grands fleuves : (i) un algorithme d'inversion robuste pour l'estimation de MES à l'aide de données Landsat-8(OLI)permet de suivre de façon systématique et fiable les variations spatio-temporelles des flux hydro-sédimentaires de surface, (ii) de même, il a été montré qu'il existe une forte relation entre le coefficient de rétrodiffusion du radar (images Sentinel-1) et les segments fluviaux d'écoulement turbulent. Cette nouvelle utilisation du radar en complément des approches classiques en géomorphologie et hydro-sédimentologie permet d'identifier des sections du fleuve où les MES sont homogénéisées, ce qui est fondamental pour le calcul des flux hydro-sédimentaires en suspension, enfin, (iii) une troisième méthodologie a été mise en œuvre pour mesurer durant le cycle hydrologique, les modifications géomorphologiques d'une île semi-submergée au centre du chenal principal. Grace à des séries topo-bathymétriques fines, associées à une modélisation 3D, l'on peut dorénavant quantifier le charriage de fond. Ces trois approches combinées permettent une évaluation plus précise du bilan hydro-sédimentaire en tenant compte des matières en suspension comme du charriage de fond. Ces études pourront servir aux gestionnaires du fleuve, confrontés à de complexes, lourdes et couteuses opérations de dragage périodiques pour maintenir sa navigabilité, ce qui est d'extrême importance pour les projets de développement socio-économiques de la frange pétrolière du bas cours de l'Orénoque. / The main objective of this thesis is to study the dynamics of hydro-sedimentary flows in the lower Orinoco from the implementation of various techniques that directly combine the measurement of in situ data and the modelling of time series of satellite images. This thesis addresses for the first time three complementary methodologies for the analysis of hydro-sedimentary flows in large rivers: i) a robust inversion algorithm for estimating suspended sediment concentration (SSC) using Landsat-8 (OLI) satellite data allows a systematic and reliable monitoring of spatial and temporal variations of surface hydro-sedimentary flows, (ii) it was shown that there is a strong relationship between the radar backscatter coefficient (Sentinel-1 images) and the turbulent flow segments in the river. This new use of radar, in addition to traditional geomorphological and hydro- sedimentological approaches, allows the identification of river sections in which suspended sediments are homogenized, which is fundamental for the calculation of suspended hydro-sedimentary flows, and finally (iii) a third methodology has been implemented to measure during the hydrological regime the geomorphological modifications of a semi-submerged island in the center of the mainstream. Thanks to a high spatial resolution topo-bathymetric series, combined with 3D modeling, it is now possible to quantify and to gain better understanding of river bed transport. These three combined approaches allow a more accurate evaluation of the hydro-sedimentary equilibrium taking into account suspended solids as well as bedload. These studies can be used by those responsible for river management, who face complex, heavy and costly periodic dredging operations to maintain their navigability, which is of extreme importance for socio-economic development projects in the Orinoco oil belt in the lower Orinoco.
409

Contribution à l'étude des interactions fluide-structure pour l'analyse de l'impact hydrodynamique d'un système de flottabilité d'hélicoptère

Malleron, Nicolas 07 April 2009 (has links) (PDF)
Les travaux réalisés au cours de cette thèse portent sur l'étude du phénomène d'impact hydrodynamique et sa modélisation. Une revue bibliographique des modèles pouvant être utilisés pour rendre compte de ce phénomène est proposée. Un modèle, dit modèle de Wagner généralisé, est ensuite développé. Proposé originellement par Zhao et Faltinsen en 1996 pour traiter de l'impact de formes 2D symétriques, il est ici étendu à des formes asymétriques et analysé de manière approfondie. Ce modèle est ensuite utilisé dans une approche couplée, pour rendre compte du comportement élastique de structures simples, se déformant au cours de l'impact. Enfin, les résultats de deux campagnes expérimentales sont présentés. La première campagne porte sur l'étude de l'impact d'une sphère élastique de taille réduite. La seconde traite de l'impact sur l'eau d'un système de flottabilité réel d'hélicoptère. Dans les deux cas, des modèles numériques sont utilisés pour tenter de reproduire au mieux l'évolution de chacun des systèmes.
410

Estimation des paramètres de transport en milieu hydro-géologique et analyse d'incertitudes

Migliore, Thomas 07 December 2009 (has links) (PDF)
Dans cette thèse, nous nous sommes intéressés à l'estimation des paramètres de transport de solutés dans un milieu poreux peu perméable, d'un point de vue théorique et appliqué, en lien avec le stockage des déchets nucléaires à vie longue en couche géologique profonde. La problématique de la gestion des déchets nucléaires est devenue durant ces dernières années une préoccupation importante de la société. Les modèles mathématiques utilisés pour le stockage des déchets en site profond sont basés sur les équations d'écoulement et de transport en milieu poreux. Ces modèles nécessitent de connaître les paramètres physiques des différentes couches géologiques. Ces paramètres (porosité et diffusion) n'étant pas accessibles directement, nous avons dans un premier temps étudié l'aspect identification de paramètres à zones fixées. Pour résoudre notre problème inverse, nous avons utilisé des méthodes déterministes (ou variationnelles) basées sur la minimisation d'un critère (ou fonction coût) quadratique, l'objectif étant de trouver l'ensemble des paramètres qui minimisent le critère. Nous avons décomposé le milieu en zones homogènes dans lesquelles les coefficients ont été identifiés (technique de zonation). Pour cela, nous avons différentié le code de convection-diffusion Traces avec le logiciel de différentiation automatique Tapenade afin d'obtenir le code adjoint de Traces. Dans un second temps, nous avons utilisé ce travail pour résoudre le problème d'identification de zones. On a cherché, partant d'une configuration géologique modifiée, à retrouver la configuration géologique réelle en identifiant les paramètres qui ont pour support ces zones. En regroupant ensuite par isovaleurs les coefficients identifiés, nous avons obtenu la configuration recherchée.

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