This work reports three reconstruction algorithms developed to address the practical issues encountered in 3D tomography diagnostics, such as the limited view angles available in many practical applications, the large scale and nonlinearity of the problems when they are in 3D, and the measurement uncertainty. These algorithms are: an algebraic reconstruction technique (ART) screening algorithm, a nonlinear iterative reconstruction technique (NIRT), and an iterative reconstruction technique integrating view registration optimization (IRT-VRO) algorithm. The ART screening algorithm was developed to enhance the performance of the traditional ART algorithm to solve linear tomography problems, the NIRT was to solve nonlinear tomography problems, and the IRT-VRO was to address the issue of view registration uncertainty in both linear and nonlinear problems. This dissertation describes the mathematical formulations, and the experimental and numerical validations for these algorithms. It is expected that the results obtained in this dissertation to lay the groundwork for their further development and expanded adaption in the deployment of tomography diagnostics in various practical applications. / Ph. D.

O cancro cítrico é uma das doenças mais temidas da citricultura devido ao seu poder de proli-feração nas fazendas, aos danos causados às plantas e aos frutos e à forma de combate adota-da pelos órgãos responsáveis através da erradicação das plantas contaminadas e de outras em sua vizinhança. No Brasil, um dos principais motivos que minimiza a eficiência da erradicação do cancro cítrico é a confirmação do diagnóstico, que necessita ser realizada em alguns laboratórios credenciados. A análise de muitas amostras em conjunto com o tempo gasto com o transporte aumenta a chance de proliferação da doença no campo. Neste trabalho aplicamos técnicas de espectroscopia da fluorescência em folhas de culturas cítricas na intenção de pro-por um método de diagnóstico do cancro cítrico a ser realizado na fazenda e com resposta em tempo real. As amostras experimentais são folhas de variedades cítricas sadias e contaminadas com cancro ou outras doenças. Iniciamos o trabalho aplicando espectroscopia da fluorescência no laboratório. Os resultados provaram a viabilidade do método, mas revelou uma enorme sobreposição de dados ao tentar discriminar o cancro de outra doença. Análises com-plementares nos revelaram que os experimentos deveriam ser feitos no campo, identificando plantas contaminadas e tomando a fluorescência de folhas sadias como referência. A espec-troscopia da fluorescência no campo foi feita com um espectrômetro portátil. O resultado nos possibilitou propor critérios de discriminação do cancro baseado em figuras de mérito. O melhor critério apresentou 79% de acertos, com 88% de sensibilidade e 68% de especificidade. Concluímos que os valores poderiam ser melhores se a espectroscopia fosse realizada com imagens, pois as variações do espectro ocorrem devido ao posicionamento da fibra na lesão do cancro. Passamos a estudar a espectroscopia das imagens da fluorescência com um sistema baseado em um espectrógrafo. Os resultados provaram a viabilidade do estudo e revelaram particularidades espaciais e espectrais das doenças. Infelizmente essa instrumentação só pode ser usada no laboratório, por isso optamos por desenvolver outro sistema mais simples e robusto, a base de uma roda de filtros com filtros passa-banda. Os re-sultados revelaram novas particularidades espaciais e espectrais das amostras, porém nos revelou a necessidade de um processamento de imagem para obter análises quantitativas. O sistema de imagens com filtro ainda foi usado em outro experimento complementar onde as imagens forneceram resultados quantitativos, provando a funcionalidade da técnica. / Citrus canker is one of the most feared diseases of citrus due to its dissemination in the farms, the damage caused to plants and fruits and how to combat adopted by national government through the eradication of infected plants and others in your neighborhood. In Brazil, one of the main reasons that minimizes the effectiveness of citrus canker`s eradication is the confir-mation of the diagnosis by specialized laboratories. The time spent to transport and to analyses many samples increases the chance of canker spreading in the field. In our work we apply spectroscopic techniques of fluorescence in leaves of citrus crops with the aim to propose a method for diagnosis of citrus canker to be held on the farm and real-time response. The expe-rimental samples are leaves of healthy citrus varieties and contaminated with canker or other diseases. We began the work by applying fluorescence spectroscopy in the laboratory. The results proved the feasibility of the method, but showed a huge overlap of data to try to dis-criminate cancer from other diseases. Further analysis revealed that those experiments should be done in the field, focusing to identify infected plants and taking the fluorescence of healthy leaves as a reference. Fluorescence spectroscopy in the field was made with a portable spectrometer. The result allowed us to propose some criteria for canker discrimination based on figures of merit. The best criteria presents 79% correct tests, with 88% sensitivity and 68% specificity. We conclude that these values could be better if the spectroscopy was performed with images, because the variations of the spectrum are due to the positioning of the fiber over the canker lesion. We study the spectroscopy of fluorescence images with a system based on a spectrograph. The results proved its feasibility and revealed spatial and spectral particular features of the diseases. Unfortunately, this instrumentation can only be used in the laborato-ry, so we decided to develop another system more simple and robust. The new system is based on a filter wheel with band-pass filters. The results revealed new spatial and spectral characteristics of the samples, but revealed the need for an image processing for quantitative analysis. This imaging system was still used in another supplementary experiment where the images have provided quantitative results, proving the functionality of the technique.

An extension of the current acetone Planar Laser-Induced Fluorescence (PLIF) was formulated for mixing studies of fluids at subcritical and supercritical conditions. The new technique, called Planar Laser-Induced Fluorescence and Phosphorescence (PLIFP), employs the difference in the mass diffusivity of the denser (liquid) to the less dense (vapor/supercritical fluid) to delineate the interface where a phase change occurs. The vapor/supercritical acetone fluorescence signal is utilized to measure of the acetone vapor density, the mixture fractions and liquid acetone phosphorescence signal to determine the location of the phase interface. The application of the technique requires the photophysical properties of vapor and liquid acetone to be known. Therefore, a series of controlled experiments were done to determine their photophysics at elevated temperatures and pressures up to T/TC = 1.2 and p/pC =1.25. The demonstration of the techniques shows it was able to provide quantitative measurements of acetone number density and the overall mixture fraction within the test chamber. Also, the size and mass of droplets that have broken off from the main jet were determined as well, though the ability is limited to small droplets (d~100 μm). In addition, the technique was able to delineate the low diffusivity (subcritical)/high diffusivity (supercritical) interface very well.

De nos jours, la combustion d'hydrocarbures est largement répandue dans de nombreuses applications, notamment la propulsion aéronautique. Toutefois, les turbomachines produisent des niveaux d'émissions d'espèces polluantes qui ne sont plus acceptés. C'est pourquoi, la compréhension des phénomènes physiques mis en jeu dans les chambres de combustion est essentielle pour aider au développement de moteurs plus propres. Dans de tels foyers, le carburant est injecté sous la forme d'un brouillard de gouttes, ce qui génère de fortes interactions avec l'écoulement d'air turbulent et la flamme. L'objectif de cette thèse est de contribuer au développement de modèles en combustion diphasique en vue d'améliorer la capacité prédictive des outils de simulation numérique. Pour cela, un nouveau moyen d'essais dédié à l'étude des flammes diphasiques turbulentes a été conçu et une base de données expérimentales a été constituée (conditions inertes et réactives). Des visualisations simultanées de la diffusion de Mie des gouttes et du taux de dégagement de chaleur ont permis de mettre en évidence une structure de flamme complexe ainsi que l'existence de différents régimes de combustion. Un autre point important de ce travail a été d'analyser statistiquement la distribution spatiale de gouttes en conditions réactives à l'aide d'une méthode de mesure originale. Cette analyse a permis de quantifier les distances inter-gouttes (plus proches voisines) en différents points de l'écoulement et d'estimer les erreurs liées au traitement des données via une approche numérique. En outre, il apparaît que la distribution spatiale des gouttes s'apparente à une loi aléatoire uniforme alors que les modèles de combustion de gouttes s'appuient souvent sur une loi régulière. / Nowadays, combustion of hydrocarbons is widespread in many engineering applications, including aeronautical propulsion. However, gas turbines produce pollutant emission levels that are no longer accepted. Therefore, understanding physical phenomena involved in combustion chambers is a major issue to help to the development of more eco-friendly engines. In aero-engine combustors, fuel is injected as a spray of droplets which generates a strong interaction with the turbulent air flow and the flame. This thesis aims at contributing to the development of two-phase combustion models to improve the predictive ability of numerical simulation tools. To do so, a new test setup dedicated to the study of two-phase turbulent flames has been designed and an experimental database has been built (non-reactive and reactive conditions). Simultaneous visualizations of Mie scattering droplets and heat release rate have highlighted a complex flame structure and the existence of different spray combustion regimes. Another important point of this work was to perform a statistical analysis of the spatial distribution of droplets under reactive conditions using an original measurement method. This analysis permitted to measure the inter-droplet distances (nearest neighbor) in different points of the flow and to assess the errors related to the processing of data through a numerical approach. It further appears that the spatial distribution of droplets is similar to an uniform random law while droplet combustion models are often based on a regular law.

O cancro cítrico é uma das doenças mais temidas da citricultura devido ao seu poder de proli-feração nas fazendas, aos danos causados às plantas e aos frutos e à forma de combate adota-da pelos órgãos responsáveis através da erradicação das plantas contaminadas e de outras em sua vizinhança. No Brasil, um dos principais motivos que minimiza a eficiência da erradicação do cancro cítrico é a confirmação do diagnóstico, que necessita ser realizada em alguns laboratórios credenciados. A análise de muitas amostras em conjunto com o tempo gasto com o transporte aumenta a chance de proliferação da doença no campo. Neste trabalho aplicamos técnicas de espectroscopia da fluorescência em folhas de culturas cítricas na intenção de pro-por um método de diagnóstico do cancro cítrico a ser realizado na fazenda e com resposta em tempo real. As amostras experimentais são folhas de variedades cítricas sadias e contaminadas com cancro ou outras doenças. Iniciamos o trabalho aplicando espectroscopia da fluorescência no laboratório. Os resultados provaram a viabilidade do método, mas revelou uma enorme sobreposição de dados ao tentar discriminar o cancro de outra doença. Análises com-plementares nos revelaram que os experimentos deveriam ser feitos no campo, identificando plantas contaminadas e tomando a fluorescência de folhas sadias como referência. A espec-troscopia da fluorescência no campo foi feita com um espectrômetro portátil. O resultado nos possibilitou propor critérios de discriminação do cancro baseado em figuras de mérito. O melhor critério apresentou 79% de acertos, com 88% de sensibilidade e 68% de especificidade. Concluímos que os valores poderiam ser melhores se a espectroscopia fosse realizada com imagens, pois as variações do espectro ocorrem devido ao posicionamento da fibra na lesão do cancro. Passamos a estudar a espectroscopia das imagens da fluorescência com um sistema baseado em um espectrógrafo. Os resultados provaram a viabilidade do estudo e revelaram particularidades espaciais e espectrais das doenças. Infelizmente essa instrumentação só pode ser usada no laboratório, por isso optamos por desenvolver outro sistema mais simples e robusto, a base de uma roda de filtros com filtros passa-banda. Os re-sultados revelaram novas particularidades espaciais e espectrais das amostras, porém nos revelou a necessidade de um processamento de imagem para obter análises quantitativas. O sistema de imagens com filtro ainda foi usado em outro experimento complementar onde as imagens forneceram resultados quantitativos, provando a funcionalidade da técnica. / Citrus canker is one of the most feared diseases of citrus due to its dissemination in the farms, the damage caused to plants and fruits and how to combat adopted by national government through the eradication of infected plants and others in your neighborhood. In Brazil, one of the main reasons that minimizes the effectiveness of citrus canker`s eradication is the confir-mation of the diagnosis by specialized laboratories. The time spent to transport and to analyses many samples increases the chance of canker spreading in the field. In our work we apply spectroscopic techniques of fluorescence in leaves of citrus crops with the aim to propose a method for diagnosis of citrus canker to be held on the farm and real-time response. The expe-rimental samples are leaves of healthy citrus varieties and contaminated with canker or other diseases. We began the work by applying fluorescence spectroscopy in the laboratory. The results proved the feasibility of the method, but showed a huge overlap of data to try to dis-criminate cancer from other diseases. Further analysis revealed that those experiments should be done in the field, focusing to identify infected plants and taking the fluorescence of healthy leaves as a reference. Fluorescence spectroscopy in the field was made with a portable spectrometer. The result allowed us to propose some criteria for canker discrimination based on figures of merit. The best criteria presents 79% correct tests, with 88% sensitivity and 68% specificity. We conclude that these values could be better if the spectroscopy was performed with images, because the variations of the spectrum are due to the positioning of the fiber over the canker lesion. We study the spectroscopy of fluorescence images with a system based on a spectrograph. The results proved its feasibility and revealed spatial and spectral particular features of the diseases. Unfortunately, this instrumentation can only be used in the laborato-ry, so we decided to develop another system more simple and robust. The new system is based on a filter wheel with band-pass filters. The results revealed new spatial and spectral characteristics of the samples, but revealed the need for an image processing for quantitative analysis. This imaging system was still used in another supplementary experiment where the images have provided quantitative results, proving the functionality of the technique.

La vitesse de flamme laminaire représente une grandeur physique clé à mesurer car elle permet d'obtenir des données fondamentales sur la réactivité, la diffusivité et l'exothermicité du carburant. Elle est également un des paramètres utilisés pour le développement et la validation des mécanismes réactionnels détaillés ainsi que pour la modélisation de la combustion turbulente. Bien que cette grandeur physique ait fait l'objet de nombreuses études expérimentales depuis plusieurs décennies, sa méconnaissance sur des carburants multi-composant dans des conditions haute-pression et haute-température similaires à celles existantes dans les chambres de combustion reste un sujet d'actualité pour les industriels des secteurs automobile et aéronautique. Au cours de cette thèse, un brûleur de configuration bec Bunsen fonctionnant avec un prémélange gazeux combustible/air a été conçu pour produire une flamme laminaire à pression élevée tout en permettant la mesure par voie optique de la vitesse de flamme laminaire de carburants multi-composant (kérosène, biocarburants de seconde génération...). La mesure est basée sur la détection du contour de flamme par diverses diagnostics optiques comme la chimiluminescence OH*, la PLIF-OH et la PLIF-acétone/aromatique. En premier lieu, les mélanges de carburants purs gazeux (CH4) ou liquide (acétone) avec de l'air ont été étudiés pour valider le brûleur expérimental et la méthodologie de mesure de la vitesse de flamme laminaire par voie optique. Les évolutions de la vitesse de flamme laminaire pour des carburants de type kérosène (composants purs, surrogate LUCHE et Jet A-1) en fonction de la pression, température de préchauffage et richesse ont été ensuite étudiées et comparées avec des simulations numériques utilisant un mécanisme réactionnel détaillé. La dernière partie de la thèse est consacrée à l'étude de l'influence des composés oxygénés présents dans un biocarburant de seconde génération de type d'essence sur la vitesse de flamme laminaire. Après avoir mesuré la vitesse de flamme laminaire de différentes molécules oxygénées, les effets d'addition de ces composés oxygénés dans le carburant ont été quantifiés / Laminar flame speed is one of the key parameters for understanding reactivity, diffusivity and exothermicity of fuels. It is also useful to validate both the kinetic chemical mechanisms as well as turbulent models. Although laminar flame speeds of many types of fuels have been investigated over many decades using various combustion methodologies, accurate measurements of laminar flame speeds of multicomponent liquid fuels in high-pressure and high-temperature conditions similar to the operating conditions encountered in aircraft/automobile combustion engines are still required. In this current study, a high-pressure combustion chamber was specifically developed to measure the laminar flame speed of multicomponent liquid fuels such as kerosene and second generation of biofuels. The architecture of the burner is based on a preheated premixed Bunsen flame burner operated in elevated pressure and temperature conditions. The optical diagnostics used to measure the laminar flame speed are based on the detection of the flame contour by using OH* chemiluminescence, OH- and acetone/aromatic- Planar laser induced fluorescence (PLIF). The laminar flame speed of gaseous CH4/air and acetone/air premixed laminar flames were first measured for validating the experimental setup and the measurement methodologies. Then, the laminar flame speeds of kerosene or surrogate fuels (neat kerosene compounds, LUCHE surrogate kerosene and Jet A-1) were investigated and compared with simulation results using detailed kinetic mechanisms over a large range of conditions including pressure, temperature and equivalence ratio. The last part of the thesis was devoted to study the effect of oxygenated compounds contained in the second generation of biofuels on the laminar flame speeds. After measuring the laminar flame speeds of various oxygenated components present in partially hydro-processed lignocellulosic biomass pyrolysis oils, the effect of these oxygenates on the flame speeds of these fuels were quantitatively investigated

The aim of this thesis is to investigate the properties of a Radio Frequency capacitive discharge at atmospheric pressure in argon. In these conditions where the pressure x distance product is around 150 Torr.cm, the discharge usually consists of several locally hot filaments. By pulsing the RF generator with an appropriate width and period, it was found possible to control the filament to glow transition in order to obtain a diffused and stable plasma.¶ The 2 mm gap between the electrodes is open to the ambient air and fed with argon via one hundred submillimetric holes regularly spread on the surface of the top electrode. This configuration allows “on-line” surface treatment of polymer films without having to turn the discharge off between successive samples. An important and lasting improvement of the polymer wettability is quickly obtained without risk of damage. The plasma diagnostic methods are emission spectroscopy and electric measurements. The Stark broadening of the Balmer β transition line of atomic hydrogen is measured to determine a plasma density of 10^15/cm3 in the filamentary mode. The glow mode density estimation was based on power balance yielding a density of 5×10^11/cm3. Emission line ratios between neutrals and Ar+ ions are used in the Saha equation to calculate the electron temperature. It results in an approximation of 1.3 eV for the glow mode and 1.7 eV for the filaments.¶ A unidimensional self-consistent fluid model is developed to gain insight into the homogeneous discharge behaviour. Poisson’s equation for the electric field is coupled to the first moments of the Boltzmann equation (continuity equation, drift-diffusion equation and energy equation). Transport and reaction coefficients are obtained from the mean energy of the electrons.¶ The model is applied to a reduced argon kinetic with the main ionization and excitation processes. Simulation results are in agreement with experimental measurements. The atmospheric pressure RF discharge is similar to a lower pressure RF discharge for which the ionization occurs mainly inside the oscillating sheaths where electrons are the most energetic

Optical imaging methods incorporating observation of the mucosal surface of organs with narrowband filtered light are diagnostic tools with a significant development in recent years and have become an integral and inseparable part of the diagnostic process of benign and malignant pathologies of the mucosal surface of various anatomical systems of the human body. Malignant and premalignant lesions of the upper aero-digestive tract (UADT) are no exception. The present work demonstrates the benefits of evaluation of changes in microvascular architecture by narrowband imaging. Its major advantage is a more accurate diagnosis of premalignant and malignant mucosal pathologies in the head and neck region based on the identification of significant changes in superficial vascularity. There is a very strong correlation of these vascular changes with the final histopathological analysis. The present data have shown that videoendoscopic examination with narrowband imaging significantly improves the distinction between benign and malignant mucosal lesions even in the UADT pathologies with a similar tendency to neoangiogenesis (squamous cell papilloma vs. squamous cell carcinoma). It also refines the determination of surface extension of tumoral changes and helps to localize and accurately diagnose tumors of...

This master´s thesis si focused on determinig methodology of optical diagnostics of the switching arc using the high-speed camera Photron SA-X2. The thesis contains basic rules for proper setup of the measurement system and the rules to adjust the camera exposure. The experiments were performed on the prototype of a parametric switching chambre, while the majority of source materials was derived from the requirements of another study which was aimed on the movement of the electode spots. The process of the first adjustment of the camera, a record edit options for the presentation purposes and the process of the 3D model design of the switching arc in SketchUp software was stated. Paper contains a comparsion of the spectral filter effect and neutral density filter effect on the final record as well. The part of the work outputs are the 3D model of the switching arc and the supporting record editing software. The paper results show a degree of the inaccuracies in a optical diagnostics made from only one direction caused by the lack of the information about third dimension.