La première partie de la thèse est consacrée au problème de l'inversion d'opérateurs dynamiques de convolution formulé en termes de symboles diffusifs. Après avoir introduit un cadre algébrique adapté, on établit plusieurs résultats garantissant la résolubilité concrète du problème de l'inversion opératorielle, en fait mal posé au sens de Hadamard, mais régularisable. La continuité de l'opération d'inversion est en particulier obtenue pour un mode de convergence convenablement affaibli. Diverses méthodes d'inversion numérique sont ensuite proposées et testées sur quelques exemples. Dans la seconde partie, divers problèmes dynamiques sont abordés de façon originale au moyen des outils développés dans la première partie. Plus particulièrement, plusieurs techniques d'identification de modèles de Volterra basées sur la paramétrisation de l'opérateur dynamique via son symbole diffusif, sont proposées et étudiées sur la base d'exemples numériques non triviaux.

Within the past decades, wavelets and associated wavelet transforms have been intensively investigated in both applied and pure mathematics. They and the related multi-scale analysis provide essential tools to describe, analyse and modify signals, images or, in rather abstract concepts, functions, function spaces and associated operators. We introduce the concept of diffusive wavelets where the dilation operator is provided by an evolution like process that comes from an approximate identity. The translation operator is naturally defined by a regular representation of the Lie group where we want to construct wavelets. For compact Lie groups the theory can be formulated in a very elegant way and also for homogeneous spaces of those groups we formulate the theory in the theory of non-commutative harmonic analysis. Explicit realisation are given for the Rotation group SO(3), the k-Torus, the Spin group and the n-sphere as homogeneous space. As non compact example we discuss diffusive wavelets on the Heisenberg group, where the construction succeeds thanks to existence of the Plancherel measure for this group. The last chapter is devoted to the Radon transform on SO(3), where the application on diffusive wavelets can be used for its inversion. The discussion of a variational spline approach provides criteria for the choice of points for measurements in concrete applications.

Simulações acopladas do escoamento reativo e dos processos de transferência de calor para o estudo de chamas são problemas dispendiosos computacionalmente. A transferência de calor por radiação em processos de combustão, devido às elevadas temperaturas, é o processo de troca energética dominante. Ainda, o comportamento altamente irregular do coeficiente de absorção com o comprimento de onda se constitui em uma dificuldade adicional na modelagem da transferência radiativa em meios participantes. Para contornar essa dificuldade modelos espectrais foram desenvolvidos com o objetivo de simular o comportamento de um gás real. Dentre esses modelos destacam-se o gás cinza (GG: Gray Gas), o mais simples, que negligencia o comportamento espectral do coeficiente de absorção, e o modelo da soma-ponderada-de-gases-cinza (WSGG: Weighted-Sum-of-Gray-Gases) onde a integração sobre todo o espectro é substituída por um número finito de gases cinza. Com o avanço de ferramentas computacionais, principalmente códigos CFD (Computational Fluid Dynamics), abordagens computacionais se tornaram atrativas frente ou em complemento às abordagens experimentais. Desse modo, o presente trabalho tem por objetivo a aplicação dos modelos WSGG e GG com novas correlações na simulação detalhada de chamas difusivas laminares de metano diluído com dióxido de carbono e nitrogênio com o código CFD comercial ANSYS/Fluent. Foram desenvolvidas rotinas de usuário (UDF: User-Defined Functions) para o acoplamento dos modelos espectrais ao código CFD. A verificação das rotinas de usuário foi realizada comparando os resultados obtidos via simulação Fluent com dados obtidos pelo modelo WSGG com um código FORTRAN próprio desenvolvido pelo grupo de pesquisa do Laboratório de Radiação Térmica (LRT/UFRGS) para o problema unidimensional de superfícies negras e infinitas preenchidas por um meio não-isotérmico e não-homogêneo. Os erros encontrados para o fluxo de calor radiativo nas superfícies e para o termo fonte radiativo ao longo do meio foram da ordem de 1% indicando o funcionamento correto das rotinas UDF acopladas ao Fluent. Por fim, as rotinas foram aplicadas na simulação numérica para chamas de potência constante com diluição dos reagentes e os dados obtidos com a solução numérica foram comparados com dados experimentais para a fração radiante e fluxo de calor radiativo. Os desvios médios encontrados para o fluxo de calor radiativo ficaram em torno de 10% para todas as chamas, excetuando as chamas com diluição de CO2 de 30%, 40% e 50%, em volume, para as quais os desvios médios ficaram em torno de 15%. O termo fonte para as chamas apontou para a predominância da emissão do meio em relação à absorção. Todas as chamas estudadas se encontram no regime opticamente fino (optically thin) para o qual, segundo apontam estudos da literatura, a escolha do modelo espectral possui impacto pequeno em resultados globais da chama como a temperatura e a concentração das espécies na mistura. Nesse aspecto os resultados encontrados concordaram com a previsão da literatura, entretanto para a transferência radiativa, o modelo GG se mostrou sensivelmente menos preciso em comparação ao modelo WSGG, principalmente para a fração radiante e para o fluxo radiativo na região da pluma aquecida, indicando a dependência do modelo espectral adotado. / Coupled simulations of the reactive flow with the heat transfer processes for flame studying are computationally demanding problems. The radiative transfer in combustion processes is the main heat transfer mechanism due to the high temperatures involved. However, the highly irregular behavior o f the absorption coefficient with the wavenumber composes in an additional difficulty on modeling the radiative transfer in participating media. In order to overcome this issue, spectral models were developed with the objective of simulate the behavior of real gases. Some of the most known models are the gray gas (GG) for which the spectral behavior of the radiative properties of the medium is neglected and the weighted-sum-of-gray-gases (WSGG) for which the integration over the entire spectrum is replaced by a summation over a finite number of gray gases with constant absorption coefficients. With the development of computational tools, mainly Computational Fluid Dynamics (CFD) codes, numerical approaches became attractive instead or in complement of experimental set ups. In this way, the present work aims to couple the WSGG and the GG models with new correlations in a detailed simulation of diffusive laminar flames of methane diluted with carbon dioxide and nitrogen with the commercial CFD code ANSYS/Fluent. User-defined functions (UDF) were developed to the coupling of the spectral models. The verification was carried out through the WSGG model by comparing the Fluent solution with a solution obtained with a FORTRAN code developed by the Thermal Radiation Laboratory (LRT/UFRGS) research group for the one-dimensional system of black surfaces filled with a non-homogeneous and non-isothermal medium. The deviations for the radiative heat flux for the walls and the radiative heat source along the domain were of 1% or less, indicating the correct coupling between the UDF routines and the CFD code. Finally, the UDF were applied in the solution of constant power flames with fuel diluted with carbon dioxide and nitrogen. The obtained data was then compared with experimental measurements for the radiant fraction and the radiative heat flux along the flame axis. The average deviations found were in order of 10% for all flames, except for the flames with 30%, 40% and 50% of CO2 dilution, in volume, for which the deviatioms found were in order of 15%. The radiative heat source was plotted and indicated for the medium emission predominance in comparison with the medium absorption. All flames studied were optically thin flames for which, studies pointed, the spectral model have minor impact over global results as flame temperature and mixture concentration. For this aspect the results found showed agreement with the literature studies predictions, however the GG model showed itself less accurate in comparison with the WSGG model for the radiant fraction and the radiative heat flux computations. So the spectral models have influence on the radiative transfer even if its effect on flame structure can be negligible.

Made available in DSpace on 2016-12-08T15:50:02Z (GMT). No. of bitstreams: 1 PGMS13DA015.pdf: 947168 bytes, checksum: 441cf02feb1ab108ff82cb196578a985 (MD5) Previous issue date: 2013-03-20 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Chemical modifications in the soil near fertilizer granules affect plant nutrient availability and, thus, knowing them may help to select the Best management practices for soil fertilization. This study comprised three experiments with the aim of: a- to evaluate the soil chemical composition around granules of calcium or ammonium phosphates when appled together with KCl as well as nutrient mobility in the soil; b- to quantify nutrient concentration in both soil and solution phases and soil solution P and K activity in the adjacencies of phosphate and potassium fertilizers; c- to evaluate nutrient uptake from maize seedlings after localized addition of phosphate fertilizers in the soil. It was used two acid soils, and treatments varied according to each experiment: in the first two it was compared phosphate sources in presence of KCl and liming; in the third, it was quantified nutrient uptake by maize plants as affected by phosphates, in a greenhouse. Rates of P2O5 e K2O were 100 mg kg-1in the first study; 700 and 1236 mg kg-1 for each soil, respectively, in the second experiment; and 200 mg/pot in the last study. The high doses were applied in order to simulate the concentrations in the near fertilizer granules. Near fertilizer granules of the mineral phosphate, the chemical composition of the soil is affected by different phosphorus sources, where the TSP proves more effective than DAP in the release of P. Localized application of phosphate fertilizers increases the movement of nutrients in the soil in which the phosphorus mobilization occurs up to four centimeters. The extraction method overestimates Mehlich 1 P values when applied to the soil TSP. DAP increases the concentration of HPO4- in soil solution. The MAP is shown to be an efficient source of P in the release and uptake by plants / As alterações químicas no solo ao redor dos grânulos de fertilizantes afetam a disponibilidade de nutrientes às plantas e o conhecimento das mesmas pode indicar as práticas e as fontes mais eficientes de fertilização do solo. Neste contexto, este estudo foi dividido em três experimentos. O primeiro experimento teve por objetivo avaliar a composição química do solo ao redor de grânulos de fosfatos de amônio ou de cálcio, aplicados juntamente com cloreto de potássio (KCl), e a mobilidade dos nutrientes por eles adicionados. O objetivo do segundo experimento foi quantificar as concentrações dos nutrientes na fase sólida e na solução do solo nas adjacências dos locais de aplicação dos fertilizantes fosfatados e potássico minerais, assim como as atividades de P e K em solução. O terceiro objetivou avaliar a absorção de P e demais nutrientes pelas plântulas de milho em função da aplicação localizada de fosfatos de cálcio e de amônio. Utilizaram-se dois solos ácidos catarinenses. Os tratamentos variaram entre os experimentos: no primeiro compararam-se os efeitos do superfosfato triplo (SFT) e do diamônio fosfato (DAP) na presença de cloreto de potássio (KCl), e as doses de P2O5 e K2O equivaleram a 100 mg kg-1 de solo. No segundo, também comparou-se o efeito do SFT e do DAP na presença ou não de KCl e de calcário, com doses de P2O5 e K2O iguais a 700 e 1236 mg kg-1 para o NV e CH, respectivamente. E no terceiro cultivaram-se plantas de milho avaliando-se o efeito da adição localizada de SFT, DAP, superfosfato simples (SS) e monoamônio fosfato (MAP), nos quais aplicou-se 200 mg de P/vaso. As doses aplicadas foram altas com a finalidade de simular as concentrações nas adjacências dos grânulos. Nas adjacências dos grânulos dos fertilizantes fosfatados minerais, a composição química do solo é afetada pelas diferentes fontes fosfatadas, onde o SFT mostrase mais eficaz que o DAP na liberação de P. A aplicação localizada dos fertilizantes fosfatada aumenta a movimentação dos nutrientes no solo, na qual a mobilização do fósforo ocorre até quatro centímetros. O método de extração Mehlich 1 superestima os valores de P quando aplica-se SFT ao solo. O DAP aumenta as concentrações de HPO4 - na solução do solo. O MAP mostra ser uma fonte eficiente na liberação de P e na sua absorção pelas plantas

Submitted by ERIK SARTORI JEUNON GONTIJO null (sartori_jg@hotmail.com) on 2017-04-20T15:59:08Z No. of bitstreams: 1 Erik Sartori Jeunon Gontijo - Tese.pdf: 6303649 bytes, checksum: e2379a13e7e45d2ce94323eddce0a8bc (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-04-25T17:47:27Z (GMT) No. of bitstreams: 1 gontijo_esj_dr_soro.pdf: 6303649 bytes, checksum: e2379a13e7e45d2ce94323eddce0a8bc (MD5) / Made available in DSpace on 2017-04-25T17:47:27Z (GMT). No. of bitstreams: 1 gontijo_esj_dr_soro.pdf: 6303649 bytes, checksum: e2379a13e7e45d2ce94323eddce0a8bc (MD5) Previous issue date: 2017-03-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Deutscher Akademischer Austauschdienst (DAAD) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O As está distribuído em diversas formas químicas em sistemas aquáticos, o que determina o seu comportamento e destino no ambiente. Nesse contexto, as substâncias húmicas (SH) têm um importante papel por serem capazes de complexar esse metaloide e alterar sua mobilidade e biodisponibilidade. O Fe também tem grande importância por poder formar complexos ternários SH-Fe-As. Apesar da química do As já ter sido bem estudada, o seu comportamento em ambientes ricos em SH e Fe ainda não é totalmente compreendido. Os objetivos desse trabalho foram investigar a distribuição do As, Al e Fe em águas superficiais de uma região mineira no sudeste do Brasil (Quadrilátero Ferrífero, QF) e entender como características de SH extraídas de diferentes regiões (Brasil e Alemanha) afetam a complexação do As(V) na presença de Fe(III). Amostras de águas foram coletadas em 12 pontos do QF, filtradas (0,45 µm) e ultrafiltradas (1 kDa) para separar as frações particulada (>0,45 µm), coloidal (<0,45 µm e >1 kDa) e livre (<1 kDa) de As, Al e Fe. A técnica de difusão em filmes finos por gradientes de concentração (DGT) foi usada em 5 dos 12 pontos para estudar a fração lábil dos elementos estudados. Carbono orgânico total (COT) e dissolvido (COD) também foram medidos. SH foram extraídas de quatro pontos (um no Brasil nas estações seca e chuvosa e três na Alemanha) para testar a influência de diferentes tipos de SH e Fe(III) na complexação do As(V). As SH foram caracterizadas e foram feitos testes de complexação utilizando sistema de ultrafiltração com membrana de 1 kDa. Todos os dados foram analisados pela rede neural de Kohonen. Os resultados mostraram que a maior parte do Al e Fe total no QF estava presente na fração particulada e o As na fração livre. A maior parte do Al e Fe dissolvido estava na fração coloidal e inerte, diferente do As que era mais lábil e potencialmente biodisponível. A maioria das amostras apresentou comportamento similar nas estações seca e chuvosa no QF. Diferenças entre os resultados de ultrafiltração e DGT foram atribuídos a distinções metodológicas e processos químicos. Os resultados de caracterização dos extratos mostraram que a maior parte do As e Fe estavam predominantemente nas frações de maior tamanho molecular. Todos os extratos de SH complexaram quantidades similares de As(V) nos testes de complexação, exceto o extrato do rio Selke, onde foi encontrado menos As(V) livre (mais complexado). Essa diferença foi atribuída ao S e à grupos N-C aromático na estrutura de SH. Isso reforça que a qualidade das SH é um importante fator capaz de influenciar o comportamento do As em ambientes ricos em matéria orgânica e Fe, que também pareceram ser fatores limitantes nas interações com o As. A rede neural de Kohonen foi uma ferramenta importante nas investigações de distribuição do As e complexação do As(V) por Fe(III) e SH. / As is distributed in different chemical forms in aquatic systems. These different forms control its behaviour and fate in the environment. The humic substances (HS) have an important role in the As cycle since they can complex this metalloid and change its mobility and bioavailability. Fe is also important because it can form ternary complexes HS-Fe-As. Although the As chemistry is well studied, the behaviour of As in HS and Fe-rich environments is not totally known. This thesis aimed to investigate the distribution of As, Al and Fe in surface waters from a mining region in the southeast of Brazil (Quadrilátero Ferrífero, QF) and understand how characteristics of HS extracted from different regions (Brazil and Germany) affect the complexation of As(V) in the presence of Fe(III). Water samples were taken in 12 points in QF, filtered (0.45 µm) and ultrafiltered (1 kDa) to separate the fractions particulate (>0.45 µm), colloidal (<0.45 µm and >1 kDa) and free (<1 kDa) of As, Al and Fe. The technique of diffusive gradients in thin films (DGT) was used in 5 of the 12 points to study the labile fraction of the elements studied. Total organic carbon (TOC) and dissolved organic carbon (DOC) were also measured. HS were extracted from four points (one in Brazil in dry and rainy seasons and three in Germany) to analyse the influence of HS from different origins and Fe(III) on the complexation of As(V). The HS were characterised and complexation experiments were performed using an ultrafiltration system with 1 kDa membrane. All data were analysed using the Kohonen neural network. The results showed that most of total Al and Fe in QF was in the particulate fraction and As was in the free fraction. Most of the dissolved Al and Fe was in the colloidal and inert fraction, while As was more labile and potentially more bioavailable. Most samples had similar behaviour in the dry and rainy seasons in the QF. Differences between results of ultrafiltration and DGT were attributed to methodological distinctions and chemical processes. The results of characterisation of extracts showed that most of As and Fe was in the fractions of higher molecular size. All HS extracts complexed similar amounts of As(V), except Selke, where a lower amount of free As(V) was detected (more complexed). This difference was attributed to S and N-aromatic C groups in HS structure. It supports that the quality of HS is an important factor able to influence the behaviour of As in environments rich in organic matter and Fe. The Kohonen neural network was an important tool in the investigation of the distribution of As and As(V) complexation by Fe(III) and HS. / FAPESP: 2012/17727-8

Simulações acopladas do escoamento reativo e dos processos de transferência de calor para o estudo de chamas são problemas dispendiosos computacionalmente. A transferência de calor por radiação em processos de combustão, devido às elevadas temperaturas, é o processo de troca energética dominante. Ainda, o comportamento altamente irregular do coeficiente de absorção com o comprimento de onda se constitui em uma dificuldade adicional na modelagem da transferência radiativa em meios participantes. Para contornar essa dificuldade modelos espectrais foram desenvolvidos com o objetivo de simular o comportamento de um gás real. Dentre esses modelos destacam-se o gás cinza (GG: Gray Gas), o mais simples, que negligencia o comportamento espectral do coeficiente de absorção, e o modelo da soma-ponderada-de-gases-cinza (WSGG: Weighted-Sum-of-Gray-Gases) onde a integração sobre todo o espectro é substituída por um número finito de gases cinza. Com o avanço de ferramentas computacionais, principalmente códigos CFD (Computational Fluid Dynamics), abordagens computacionais se tornaram atrativas frente ou em complemento às abordagens experimentais. Desse modo, o presente trabalho tem por objetivo a aplicação dos modelos WSGG e GG com novas correlações na simulação detalhada de chamas difusivas laminares de metano diluído com dióxido de carbono e nitrogênio com o código CFD comercial ANSYS/Fluent. Foram desenvolvidas rotinas de usuário (UDF: User-Defined Functions) para o acoplamento dos modelos espectrais ao código CFD. A verificação das rotinas de usuário foi realizada comparando os resultados obtidos via simulação Fluent com dados obtidos pelo modelo WSGG com um código FORTRAN próprio desenvolvido pelo grupo de pesquisa do Laboratório de Radiação Térmica (LRT/UFRGS) para o problema unidimensional de superfícies negras e infinitas preenchidas por um meio não-isotérmico e não-homogêneo. Os erros encontrados para o fluxo de calor radiativo nas superfícies e para o termo fonte radiativo ao longo do meio foram da ordem de 1% indicando o funcionamento correto das rotinas UDF acopladas ao Fluent. Por fim, as rotinas foram aplicadas na simulação numérica para chamas de potência constante com diluição dos reagentes e os dados obtidos com a solução numérica foram comparados com dados experimentais para a fração radiante e fluxo de calor radiativo. Os desvios médios encontrados para o fluxo de calor radiativo ficaram em torno de 10% para todas as chamas, excetuando as chamas com diluição de CO2 de 30%, 40% e 50%, em volume, para as quais os desvios médios ficaram em torno de 15%. O termo fonte para as chamas apontou para a predominância da emissão do meio em relação à absorção. Todas as chamas estudadas se encontram no regime opticamente fino (optically thin) para o qual, segundo apontam estudos da literatura, a escolha do modelo espectral possui impacto pequeno em resultados globais da chama como a temperatura e a concentração das espécies na mistura. Nesse aspecto os resultados encontrados concordaram com a previsão da literatura, entretanto para a transferência radiativa, o modelo GG se mostrou sensivelmente menos preciso em comparação ao modelo WSGG, principalmente para a fração radiante e para o fluxo radiativo na região da pluma aquecida, indicando a dependência do modelo espectral adotado. / Coupled simulations of the reactive flow with the heat transfer processes for flame studying are computationally demanding problems. The radiative transfer in combustion processes is the main heat transfer mechanism due to the high temperatures involved. However, the highly irregular behavior o f the absorption coefficient with the wavenumber composes in an additional difficulty on modeling the radiative transfer in participating media. In order to overcome this issue, spectral models were developed with the objective of simulate the behavior of real gases. Some of the most known models are the gray gas (GG) for which the spectral behavior of the radiative properties of the medium is neglected and the weighted-sum-of-gray-gases (WSGG) for which the integration over the entire spectrum is replaced by a summation over a finite number of gray gases with constant absorption coefficients. With the development of computational tools, mainly Computational Fluid Dynamics (CFD) codes, numerical approaches became attractive instead or in complement of experimental set ups. In this way, the present work aims to couple the WSGG and the GG models with new correlations in a detailed simulation of diffusive laminar flames of methane diluted with carbon dioxide and nitrogen with the commercial CFD code ANSYS/Fluent. User-defined functions (UDF) were developed to the coupling of the spectral models. The verification was carried out through the WSGG model by comparing the Fluent solution with a solution obtained with a FORTRAN code developed by the Thermal Radiation Laboratory (LRT/UFRGS) research group for the one-dimensional system of black surfaces filled with a non-homogeneous and non-isothermal medium. The deviations for the radiative heat flux for the walls and the radiative heat source along the domain were of 1% or less, indicating the correct coupling between the UDF routines and the CFD code. Finally, the UDF were applied in the solution of constant power flames with fuel diluted with carbon dioxide and nitrogen. The obtained data was then compared with experimental measurements for the radiant fraction and the radiative heat flux along the flame axis. The average deviations found were in order of 10% for all flames, except for the flames with 30%, 40% and 50% of CO2 dilution, in volume, for which the deviatioms found were in order of 15%. The radiative heat source was plotted and indicated for the medium emission predominance in comparison with the medium absorption. All flames studied were optically thin flames for which, studies pointed, the spectral model have minor impact over global results as flame temperature and mixture concentration. For this aspect the results found showed agreement with the literature studies predictions, however the GG model showed itself less accurate in comparison with the WSGG model for the radiant fraction and the radiative heat flux computations. So the spectral models have influence on the radiative transfer even if its effect on flame structure can be negligible.

This thesis is part of the project undertaken to develop a diffusive acoustic confocal imaging system (DACI) that aims to differentiate between healthy and the diseased tissues in the prostate. Speed of sound is chosen as the tool to quantify the alterations in the tissues’ mechanical properties at different pathological states. The current work presents a scanning configuration that features three components: an acoustic emitter, a focusing mirror and a point receiver. The focusing mirror brings the collimated acoustic beam from the emitter into a focused probe position, which needs to be located within the bladder or at the near surface of the prostate. This position is introduced as the virtual source, where the acoustic intensity diffusively scatters into all directions and propagates through the specimen. The system design was simulated using ZEMAX and COMSOL to validate the concept of the virtual source. Lesions in a phantom prostate were found in the simulated amplitude and phase images. The speed of sound variation was estimated from the 1D unwrapped phase distribution indicating where the phase discontinuities existed. The measurements were conducted in a water aquarium using the tissue-mimicking prostate phantom. Two-dimensional projected images of the amplitude and the phase distributions of the investigating acoustic beam were measured. A USRP device was set up as the signal generation and acquisition device for the experiment. Two different signal extractions methods were developed to extract the amplitude and the phase information. The experimental results were found to generally agree with the simulation results. The proof-of-concept design was successful in measuring both the phase and the amplitude information of the acoustic signal passing through the prostate phantom. In future, the 2D/3D speed of sound variation needs to be estimated by an appropriate image reconstruction method. / Graduate / 2018-12-06

Ce travail de thèse est consacré à l’étude des déformations d’interfaces liquides par l’action d’une onde laser continue. Nous démontrons que la diffusion élastique d'une onde laser dans un milieu turbide induit une force diffusive en volume qui donne naissance à des écoulements permanents au sein du fluide. Les contraintes visqueuses associées à ces écoulements, à l’approche d’une interface liquide molle, peuvent engendrer la déformation de celle-ci jusqu’à la déstabiliser et former un jet. Dans ce manuscrit, nous présentons une étude expérimentale de ce nouveau couplage lumière-fluide complétée par des simulations numériques. Nous présentons également une étude des déformations et instabilité d'interfaces par la pression de radiation optique, due au contraste d’indice de réfraction entre les deux phases liquides en coexistence, dans des milieux transparents. Nous avons enfin analysé la combinaison de ces deux couplages dans les milieux turbides, force diffusive et pression de radiation participant différemment à la déformation d’interfaces liquides. Pour ce faire, nous avons eu recours à différents systèmes fluides turbides et transparents, ayant pour particularité principale de présenter une tension interfaciale extrêmement faible. / This thesis work is dedicated to liquid interface deformations from a continuous laser wave. We demonstrate that elastic scattering of the incident wave in turbid medium induces a scattering force density giving birth to permanent bulk flows in the fluid. Near a soft interface, viscous stresses associated to these flows can deform the interface up to instability and produce a liquid jet. In this manuscript, we report an experimental study dedicated to this new light-fluid coupling in combination with numerical simulations. We also study interface deformations and instability induced by radiation pressure, due to refractive index contrast between the two liquid phases in coexistence, in transparent fluids. We finally analyzed the combination of both couplings in turbid media, scattering force and radiation pressure which differently operate for the interface deformation. To do this, we used different turbid and transparent fluids systems, which have the main particularity to present very low interfacial tension.

Les apports d’eaux souterraines (Submarine Groundwater Discharge : SGD) peuvent constituer des apports considérables d'eau et de nutriments ou de contaminants en zone côtière. Le suivi des radio-éléments (radon, radium) dans ces zones permet de tracer les apports de SGD et leurs bilans de masse permettent de quantifier leurs flux. Cette méthode est utilisée depuis des années, mais les termes des bilans aux interfaces restent difficiles à appréhender. L'objectif de cette thèse est d'apporter des précisions sur ces termes afin de permettre une meilleure quantification des flux de SGD. Pour l'interface air-eau, les flux de dégazage du radon vers l'atmosphère ont été estimés pour différentes conditions de vent sur l’étang de Berre. Un dégazage permanent, même sans vent, a été mis en évidence. Pour l'interface sédiment-eau, nous décrivons une méthode de calcul et d’évaluation du flux diffusif du radon et proposons une nouvelle approche pour estimer celui du radium. Dans la lagune de Mar Menor, les flux de SGD estimés sont 5 à 200 fois plus élevés que les apports d'eau par les rivières et sont majoritairement causés par de la recirculation d’eau à travers les sédiments. Pour la première fois les suivis de radio-éléments ont été combinés à un modèle hydrodynamique, ce qui a permis de localiser précisément les SGD. L'étude du système karstique de la source de la calanque de Port-Miou a mis en évidence un système bicouche de la colonne d'eau. La combinaison des bilans en radio-éléments, d'eau et de sel nous a permis d'estimer un débit de la source très proche de celui mesuré par différence de pression, attestant ainsi de la fiabilité de cette méthode pour les systèmes karstiques. / Submarine Groundwater Discharges (SGD) may represent important inputs of water, nutrients as well as contaminants to the coastal zone. Monitoring radionuclides (radon, radium) in those areas allows to trace SGD inputs while their fluxes may be quantified through their mass balances. This method has been used for many years, even though the terms from the mass balance at these interfaces remain difficult to manage. The objective of this thesis is to develop methods to better describe and evaluate these terms, in order to get a better quantification of SGD fluxes. For the air-water interface, the radon atmospheric fluxes have been estimated for different wind conditions on the Berre lagoon. A permanent flux, even without wind, has been highlighted. For the sediment-water interface, new methods are proposed here in order to calculate and evaluate the radon diffusive flux, as well as a new approach for estimating the radium diffusive flux. In the Mar Menor, the estimated SGD fluxes are 5 to 200 times higher than water river inputs and are predominantly caused by lagoon water recirculation through sediments forced by tidal pumping. For the first time, the monitoring of radionuclides in this lagoon was combined to a hydrodynamic model, allowing to locate precisely the SGD inputs. The study of the karstic spring of the Port-Miou calanque shows a two-layer system in the water column. The combination of radionuclides, water and salt mass balances leads to calculate a spring flux similar to the one measured by pressure gradient, which confirms the reliability of this method for karstic systems.

Tato dizertační práce zkoumá vývoj techniky difúzního gradientu v tenkém filmu (DGT) pro stanovení rtuti (Hg) a dalších stopových kovů a dále rozšířené možnosti použití této techniky. Technika DGT je v této práci vyvinuta pro stanovení Hg a dalších stopových prvků v různých kapalných médiích. Dvě rozdílná sorpční média specifická pro rtuť byla testována pro použití v technice DGT – Purolite S924 a cysteinem modifikovaná aminopropyl silika (CAPS). Purolite S924 je komerčně dostupný chelatační iontoměnič, CAPS byla připravena v laboratorních podmínkách imobilizací cysteinu na 3-aminopropyl funkcionalizovanou siliku pomocí glutaraladehydu. Obě testovaná sorpční média ukázala slibný aplikační potenciál pro užití v technice DGT díky funkčnosti v roztocích o širokém rozsahu pH i iontové síly. Funkčnost DGT s novými sorpčními médii byla porovnána s technikami DGT s běžně používanými sorbenty Chelex-100 a 3-merkaptopropylfunkcionalizovanou silikou. Hlavní výhodou sorpčních médií Purolite S924 a CAPS je schopnost současného stanovení Hg a dalších stopových kovů (Cd, Pb, Co, Ni, Cu). Vzhledem k odlišným požadavkům na sorpční média používaná v technice DGT nebylo dosud současné kvantitativní stanovení Hg a dalších stopových kovů možné. Doposud byly zapotřebí dvě samostatné techniky DGT – jedna pro Hg a druhá pro další stopové kovy, což zvyšuje množství vzorků pro analýzu a množství použitého spotřebního materiálu. Technika DGT s CAPS byla použita pro stanovení koncentrací kovů v námořních přístavech v Oostende a Zeebrugge na belgickém pobřeží Severního moře. Přestože byla technika DGT původně představena pro použití v analytické chemii životního prostředí, byla v této práci zkoumáno i použití této techniky v analýze potravin. V prostředí rybí omáčky byla ověřena funkčnost techniky DGT a stanoveny difúzní koeficienty Hg a dalších stopových prvků. Technika DGT byla následně použita pro stanovení koncentrace rtuti a dalších stopových kovů v různých komerčně dostupných vzorcích rybí omáčky. Výsledky nově navrhnutého analytického postupu s použitím techniky DGT byly porovnány s výsledky přímé analýzy atomovou absorpční spektroskopií s termální dekompozicí a amalgamací zlatem (TD-AAS) a po mikrovlnném rozkladu vzorků omáčky také s výsledky sektorové hmotnostní spektrometrie s indukčně vázanou plazmou (SF-ICP-MS). Díky předkoncentrační schopnosti techniky DGT byly dosaženy nižší detekční limity ve srovnání s TD-AAS nebo SF-ICP-MS. Technika DGT díky schopnosti oddělení analytů z komplexní matrice rybí omáčky rovněž snížila opotřebení a koroze kovových částí použitých instrumentálních technik.