Radioisótopos de gálio são estudados e avaliados para aplicações médicas desde 1949. Nos últimos 50 anos 67Ga tem sido amplamente utilizado no diagnóstico de diversas patologias, incluindo lesões inflamatórias crônicas e agudas, bacterianas ou estéreis e diversos tipos de tumores. No Brasil 30% das clinicas que prestam serviços de Medicina Nuclear utilizam o Citrato de 67Ga com uma demanda de distribuição no IPEN-CNEN/SP de 37 GBq (1 Ci) por semana. O 67Ga apresenta meia-vida física de 3,26 dias (78 horas) e decai 100% por captura eletrônica para o 67Zn estável. Seu decaimento inclui a emissão de raios γ com energias de 93,3 keV (37%), 184,6 keV (20,4%), 300,2 keV (16,6%) e 888 keV (26%). No IPEN o 67Ga era produzido a partir da reação 68Zn(p, 2n)67Ga. Após a irradiação, o alvo era totalmente dissolvido em HCl concentrado e a solução percolada em resina catiônica DOWEX 50W-X8, 200-400 mesh, condicionada em HCl 10 mol L-1. Zinco, níquel e cobre eram eluídos em HCl 10 mol L-1 e o 67Ga em HCl 3,5 mol L-1. O produto final era obtido na forma de citrato de 67Ga. Este trabalho apresenta um método inédito, rápido, direto e eficiente de separação química e obtenção de 67GaCl3 a partir da difusão térmica (aquecimento do alvo) aliada à extração em ácido acético concentrado. A purificação foi realizada por cromatografia de troca iônica. Realizou-se a eletrodeposição do zinco natural em placas de cobre niquelado como substrato e os depósitos de zinco obtidos foram aderentes ao substrato, levemente brilhantes e uniformes. Os alvos foram irradiados com prótons de 26 MeV e corrente integrada de 10 μA.h. Após a irradiação, os alvos foram aquecidos a 300 °C por 2 horas e colocados em contato com ácido acético concentrado por 1 hora. O rendimento médio de extração de 67Ga obtido foi de (72±10)%. Esta solução foi evaporada e o resíduo foi retomado em NH4OH 0,5 mol L-1. O 67Ga foi purificado em resina catiônica Dowex 50WX8 em meio de NH4OH. A recuperação obtida foi de (98 ± 2) %, de 67Ga. O eluido foi evaporado e retomado em HCl 0,1 mol L-1. A pureza química foi verificada por ICP-OES encontrando-se (2 ± 1) μg mL -1 de zinco. As concentrações de ferro, cobre e níquel foram inferiores ao limite de detecção do método e aos limites de utilização de 67Ga. A pureza radionuclídica foi verificada por espectroscopia-γ utilizando um detector de germânio Hiper-Puro encontrando-se valor superior a (99,9%). Este método inédito permite a obtenção de 67Ga com alta pureza química, radioquímica e radionuclídica em condições de processamento menos agressivas e corrosivas que o método comumente utilizado. / Radioisotopes of gallium have been studied and evaluated for medical applications since 1949. Over the past 50 years 67Ga has been widely used in the diagnosis of various diseases, including acute and chronic inflammatory lesions, bacterial or sterile and several types of tumors. In Brazil 30% of clinics that provide services for Nuclear Medicine use 67Ga citrate and the demand for 67Ga at IPEN-CNEN/SP is 37 GBq (1 Ci)/week. The 67Ga presents physical half-life of 3.26 days (78 hours) and decays 100% by electron capture to stable 67Zn. Its decay includes the emission of γ rays with energies of 93.3 keV (37%), 184.6 keV (20.4%), 300.2 keV (16.6%) and 888 keV (26%). In the past 67Ga was produced by the reaction 68Zn (p, 2n) 67Ga at IPEN-CNEN/SP. After irradiation, the target was dissolved in concentrated HCl and the solution percolated through a cationic resin DOWEX 50W-X8, 200-400 mesh, conditioned with 10 mol L -1 HCl. Zinc, nickel and copper were eluted in 10 mol L-1 HCl and 67Ga 3.5 mol L-1 HCl. The final product was obtained as 67Ga citrate. This work presents a new, fast, direct and efficient method for the chemical separation of 67Ga by thermal diffusion (heating of the target) combined with concentrated acetic acid extraction. Purification was performed by ion exchange chromatography. Natural zinc electrodeposition was performed on nickel/copper plates as substrate and the zinc deposits were adherent to the substrate, slightly shiny and uniform. The targets were irradiated with 26 MeV protons and integrated current of 10 μA.h. After irradiation, the targets were heated at 300 °C for 2 hours and placed in contact with concentrated acetic acid for 1 hour. The average yield of extraction of 67Ga was (72 ± 10)%. This solution was evaporated and the residue was taken up in 0.5 mol L-1 NH4OH. The 67Ga was purified on cationic resin Dowex 50WX8 in NH4OH medium. The 67Ga recovery was (98 ± 2)%. This solution was evaporated and taken up in 0.1 mol L-1 HCl. The chemical purity was evaluated by ICP-OES that resulted in (2 ± 1) μg mL-1 of zinc. The concentration of iron, copper and nickel was lower than the detection limits and also than the utilization limits for 67Ga. The radionuclidic purity was greater than (99.9%). This method showed to be suitable to obtain high purity 67Ga in less aggressive chemical conditions than before.

Ce mémoire traite de la limitation de courant à partir de supraconducteurs HTc. L'utilisation de la transition naturelle d'un état supraconducteur vers un état dissipatif est envisagée pour limiter les courants de défaut sur les réseaux de distribution électrique. Cette application de la supraconductivité est très prometteuse puisque aucune solution conventionnelle ne réalise cette fonctionnalité pour la haute tension. Le gain réalisé par l'installaton de limiteurs de courant serait une densification des réseaux électriques et une amélioration de la qualité de l'énergie distribuée. Cette étude se scinde en deux points. Le premier concerne l'étude expérimentale du comportement de différents matériaux supraconducteurs HTc pour la limitation de courant. Cette caractérisation a été menée en régime nominal alternatif (mesures des pertes) et en régime de défaut. Dans le cadre de cette étude, le matériau YBCO mono domaine a fait l'objet d'une analyse approfondie à haute température. Un travail de modélisation numérique visant à prédire les conséquences d'une transition inhomogène et à estimer les pertes en régime assigné a également été mené. Afin de valider la faisabilité d'un appareillage haute tension, un démonstrateur 1 kV / 100 A constitué de 43 méandres d'YBCO texturé a été testé à une température de 90,5 K. Cette étude s'est également focalisée sur la dynamique de la transition des matériaux supraconducteurs. Nos expériences semblent montrer que la transition est plus homogène au voisinage de Tc. Cette observation est principalement justifiée par la faible valeur de Jc au voisinage de Tc, par des considérations thermiques (meilleure propagation du front de transition) et magnétiques (ancrage magnétique et mécanisme avalancheux de la transition différents près de Tc). Des résultats expérimentaux mettent également le doigt sur l'importance des échanges thermiques latéraux sur la transition des supraconducteurs. L'analyse menée montre que l'énergie dissipée au sein du matériau étudié semble l'être de façon localisée.

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Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2018-06-13T13:06:26Z No. of bitstreams: 1 JOÃO TAVARES NUNES - DISSERTAÇÃO PPGEA 2011..pdf: 11091920 bytes, checksum: d63185b45641e3f0c461d42c911f608b (MD5) / Made available in DSpace on 2018-06-13T13:06:26Z (GMT). No. of bitstreams: 1 JOÃO TAVARES NUNES - DISSERTAÇÃO PPGEA 2011..pdf: 11091920 bytes, checksum: d63185b45641e3f0c461d42c911f608b (MD5) Previous issue date: 2011-09 / Com o intuito de aproveitar o fruto do mandacaru produzido na região semiárida do Nordeste visando à produção de polpas e sucos, o presente trabalho teve como objetivo determinar as principais propriedades termofísicas, massa específica, condutividade térmica, difusividade térmica e calor específico, além do comportamento reológico das polpas integral e concentradas do fruto do mandacaru até os teores de 35 e 56 °Brix. A massa específica foi determinada pelo método picnométrico; para a difusividade térmica utilizou-se o método do cilindro infinito de Dickerson; o valor do calor específico foi obtido usando através do método das misturas e a condutividade térmica foi calculada por método indireto. Equações propostas em literatura também foram utilizadas para estimar as propriedades termofísicas. Os dados reológicos foram determinados utilizando-se um viscosímetro Brookfield e os modelos de Casson, Ostwald-de-Waelle e Herschel-Bulkley, ajustados aos dados experimentais, ressaltando-se que o último modelo foi o que proporcionou os melhores ajustes. As polpas com a concentração de 12 °Brix apresentaram comportamento não-newtoniano do tipo dilatante; no entanto, as polpas com concentrações de 35 e 56 °Brix apresentaram comportamento não newtoniano do tipo pseudoplástico. A viscosidade foi influenciada pela concentração e temperatura. A polpa integral do fruto do mandacaru foi considerada um alimento ácido, com baixo conteúdo mineral, alto teor de umidade e de atividade de água, com predominância da intensidade de amarelo. As propriedades termofísicas se mantiveram em faixa esperada para polpas de frutas. A massa específica aumentou com o aumento do teor de sólidos solúveis totais e o calor específico e a difusividade térmica diminuíram com o aumento da concentração. Das equações utilizadas para estimar a massa específica, calor específico, difusividade térmica e condutividade térmica, apenas as referentes a massa específica podem ser consideradas razoáveis para todas as amostras, com erros abaixo de 20%. / In order to make better use of mandacaru fruit grown in the semiarid Northeast of Brazil for pulp and fruit production, this study sought to determine the main thermophysical properties, density, thermal conductivity and specific heat capacity, in addition to rheological behavior of whole and concentrated mandacaru fruit pulp up to a content of 35 and 56 °Brix. Density was determined by the pycnometric method; the Dickerson infinite cylinder method was used for thermal diffusivity; the heat capacity value was obtained by the method of mixtures and thermal conductivity by the indirect method. Equations proposed in the literature were also applied to estimate thermophysical properties. Rheological data were determined using a Brookfield viscometer and Casson, Ostwald-de-Waelle and Herschel-Bulkley models, fit to experimental data, with the last model exhibiting best fit. Pulps with a concentration of 12 °Brix showed dilatant non- Newtonian behavior; however, those with concentrations of 35 and 56 °Brix displayed pseudoplastic non-Newtonian behavior. Viscosity was influenced by concentration and temperature. Mandacaru whole fruit pulp, predominantly yellow, was considered acidic, with low mineral content, high moisture content and water activity. Thermophysical properties were in the expected range for fruit pulp. Density increased with a rise in soluble solid content, while heat capacity and thermal diffusivity decreased with increased concentrations. Of the equations used to estimate density, heat capacity, thermal diffusivity and thermal conductivity, only those related to density are adequate for ali samples, with an error of less than 20%.

Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2018-06-13T14:15:26Z No. of bitstreams: 1 JOSÉ DIVÂNIO PEREIRA DE OLIVEIRA - DISSERTAÇÃO PPGEA 2011..pdf: 15315292 bytes, checksum: e9b24518134206b0e9339d2a725d179a (MD5) / Made available in DSpace on 2018-06-13T14:15:26Z (GMT). No. of bitstreams: 1 JOSÉ DIVÂNIO PEREIRA DE OLIVEIRA - DISSERTAÇÃO PPGEA 2011..pdf: 15315292 bytes, checksum: e9b24518134206b0e9339d2a725d179a (MD5) Previous issue date: 2011-09 / O consumo de carne congelada é cada vez maior, sobretudo nas grandes cidades, tornando-se imprescindíveis estudos mais detalhados dos processos de congelamento e sua influência no produto destinado ao consumidor. O principal objetivo deste trabalho foi determinar a cinética de congelamento e avaliar as alterações físico-químicas do lombo da carne caprina e ovina, submetido a quatro temperaturas de congelamento: -22,5 e -45 °C (freezer comercial), -170 °C (vapor de nitrogénio líquido) e -196 °C (imersão no nitrogénio líquido). Foram realizadas as análises físico-químicas de teor de água, pH, acidez, cinzas e proteínas, de acordo com o Instituto Adolfo Lutz enquanto para os atributos textura, ruptura da fibra e resistência de corte, as amostras foram realizadas em texturômetro da marca TA.XT plus. O lombo da carne ovina a -22,5 e -45 °C congelou mais rapidamente que a do lombo da carne caprina, cujos tempos foram iguais a 10200 e 10800 segundos; 6240 e 6480 segundos, respectivamente; Já nas temperaturas de -170 e -196 o lombo da carne apresentou ligeira diferença no tempo de congelamento com a carne caprina congelando de maneira mais rápida em aproximadamente 1920 segundos com relação à carne ovina, que foi de 1940 segundos e 120 e 125 segundos, respectivamente. As difusividades efetivas médias (am) do lombo da carne caprina e ovina apresentaram tendência de aumento com a diminuição da temperatura de congelamento. Os maiores valores de teor de água, pH, acidez e proteínas do lombo da carne caprina foram iguais a 76,8447% (-45°C); 5,756 (-45 °C), 5,733 (-90 °C) e 5,770 (-196 °C); 0,052% (-90 °C); e 23,490% (-170 °C), respectivamente; por outro lado, teores de água, pH, acidez e proteínas, foram iguais a 71,6773% (-90 °C), 5,530 (-22,5 °C), 0,032% (-170 °C) e 18,390 (-196 °C), respectivamente. No lombo da carne caprina os maiores e menores valores para o teor de água foram iguais a 77,6433 (-22,5 °C) e 70, 5390 (-90 °C); pH iguais a 5,753 (-196 °C) e 5,610 (-22,5 °); acidez iguais a 0,047, 0,045, 0,044 % (-22,5, -45 e -170°C)e 0,040 (- 196 °C); proteínas iguais a 20,643 e 20,953 % (-45 e -90 °C) e 18,923 e 18,720 (-22,5 e - 170 °C), mas as cinzas não apresentaram alterações significativas. A redução da temperatura de congelamento proporcionou tendência de diminuição da força de corte e ruptura das fibras do lombo da carne caprina e ovina. / Frozen meat consumption has increased especially in large cities, calling for more exhaustive rescarch concerning the freezing process and its influence on consumer products. The main objective of present study is to determine the freezing kinetics and evaluate the physical and chemical changes that occur in the lamb loin and goat meat. Both the lamb loin and goat meat were exposed to four freezing temperatures, -22.5 and - 45 C (freezer trade), -170 C (liquid nitrogen vapor) and -196 ° C (immersion in liquid nitrogen). A physical-chemical water content analysis, including pH, acidity, ash and protein content was conducted in conformity with the Instituto Adolfo Lutz's, norms whereas for texture attributes of fiber rupture and resistance, samples cutting were done in brand texturometer TA . XT plus. The lamb loin -22.5 and -45 ° C froze faster than the goat meat , whose times were equal to 10200 and 10800 / 2, 6240 and 6480 / 2, respectively. At temperatures of -170 and -196 °C, the loin meat exhibited a slight difference in freezing weather, with freezing goat meat quickly, in about 1920 / 2, in relation to lamb, which was 1940 / 2 and 120 125 seconds, respectively. The mean effective diffusivities (am) of loin meat goats and sheep tended to increase with decreasing freezing temperature. The highest values of water content, pH, acidity and protein loin of goat meat were equal to 76.8447% (-45 ° C) 5.756 (-45 ° C), 5.733 (-90 C) and 5.770 (-196 ° C), 0.052% (-90 C) and 23.490% (-170 ° C), respectively. While the lower water content, pH, acidity and protein were equal to 71.6773% (-90 C), 5.530 (-22.5 C), 0.032% (-170 ° C) and 18.390 (-196 degrees C), respectively. On the back of the goat meat, the highest and lowest values for water content were equal to 77.6433 (-22.5 C) and 70, 5390 (-90 C), pH equal to 5.753 (-196 ° C) and 5.610 (-22.5 °); acidity equal to 0.047, 0.045, 0.044% (-22.5, -45 and - 170 ° C) and 0.040 (-196 ° C), protein equal to 20.643 and 20.953% (-45 and -90 C) and 18.923 and 18.720 (-22.5 and - 170 ° C), while the ash did not change significantly. The reduction of the freezing temperature gave a trend of cutting force and rupture of the fibers of the loin of lamb and goat meat.

Les travaux de cette thèse concernent l’étude des phénomènes de diffusion thermique en vue de disposer de modèles de connaissances (approche boîte blanche) pour l’analyse, la synthèse fréquentielle et la validation temporelle de commandes robustes. La Partie 1 composée du chapitre 1 se focalise sur les définitions et les interprétations de l’opérateur intégro-différentiel non entier. La problématique de la simulation, dans le domaine temporel, des SDNE est précisée. La Partie 2 intitulée "Etude analytique" regroupe deux chapitres dont l’objectif est de faire une analyse fine des comportements d’ordre non entier, d’abord dans un milieu semi-infini (chapitre 2), puis dans un milieu fini (chapitre 3). La Partie 3, intitulée "Simulation numérique des réponses temporelles" regroupant deux chapitres (4 et 5), a pour finalité la mise en oeuvre de la partie « Procédé thermique » (modèle de validation d’un milieu fini) d’un simulateur des réponses temporelles d’une boucle de régulation thermique. / The work of this thesis concerns the study of the thermal diffusion phenomena to have a model (white box approach) for the analysis, the frequency synthesis and the time validation of robust commands. The Part 1 composed of chapter 1 focuses on the definitions and the interpretations of the integro-differential non-integer operator. The simulation problem in the time domain of the fractional differential systems is specified. Part 2 entitled "Analytical Study" includes two chapters whose objective is to make a detailed analysis of the fractional order behavior, first in a semi-infinite medium (chapter 2), then in a finite medium (chapter 3). Part 3, entitled "Numerical simulation of time responses" combining two chapters (4 and 5), aims the implementation of the "thermal process" plant (model validation of a finite medium) of a simulator of the thermal control loop time responses.

This dissertation deals with the potential of thermal field-flow fractionation (ThFFF) for the multidetection-based analysis of polymers with complex topology to prove its capability in resolving polymer branching characteristics from measured thermophoretic properties. For that, not yet existent but necessary profound advances in the theory of ThFFF and as well, thermophoresis of branched polymers were generated to allow a full exploitation of the method in the elucidation of polymer topology. Exemplary, two different libraries of branched polymer model systems based on aliphatic-aromatic polyesters and on a new type of short chain branched polyethylene were investigated. On top, the potential of the optimized ThFFF theory was assessed in the context of crosslinked polymer architectures and shines light onto the so far controversially debated topic of electron beam irradiation effects on thermoplastic polyurethane.

Les conséquences liées à la présence de gradients thermiques sur le transfert de matière en milieu poreux sont encore aujourd’hui mal appréhendées, essentiellement en raison de la complexité induite par la présence de phénomènes couplés (thermodiffusion ou effet Soret). Le but de cette thèse est d’étudier et de comprendre l’influence que peut avoir un gradient thermique sur l’écoulement d’un mélange. L’objectif principal est de déterminer les coefficients effectifs modélisant les transferts de chaleur et de matière en milieux poreux, et en particulier le coefficient de thermodiffusion effectif. En utilisant la technique de changement d’échelle par prise de moyenne volumique nous avons développé un modèle macroscopique de dispersion incluant la thermodiffusion. Nous avons étudié en particulier l'influence du nombre de Péclet et de la conductivité thermique sur la thermodiffusion. Les résultats ont montré que pour de faibles nombres de Péclet, le nombre de Soret effectif en milieu poreux est le même que dans un milieu libre, et ne dépend pas du ratio de la conductivité thermique (solide/liquide). À l'inverse, en régime convectif, le nombre de Soret effectif diminue. Dans ce cas, un changement du ratio de conductivité changera le coefficient de thermodiffusion effectif. Les résultats théoriques ont montré également que, lors de la diffusion pure, même si la conductivité thermique effective dépend de la connectivité de la phase solide, le coefficient effectif de thermodiffusion est toujours constant et indépendant de la connectivité de la phase solide. Le modèle macroscopique obtenu par cette méthode est validé par comparaison avec des simulations numériques directes à l'échelle des pores. Un bon accord est observé entre les prédictions théoriques provenant de l'étude à l’échelle macroscopique et des simulations numériques au niveau de l’échelle de pores. Ceci démontre la validité du modèle théorique proposé. Pour vérifier et consolider ces résultats, un dispositif expérimental a été réalisé pour mesurer les coefficients de transfert en milieu libre et en milieu poreux. Dans cette partie, les nouveaux résultats expérimentaux sont obtenus avec un système du type « Two-Bulb apparatus ». La diffusion et la thermodiffusion des systèmes binaire hélium-azote et hélium-dioxide de carbone, à travers des échantillons cylindriques remplis de billes de différents diamètres et propriétés thermiques, sont mesurées à la pression atmosphérique. La porosité de chaque milieu a été déterminée par la construction d'une image 3D de l'échantillon par tomographie. Les concentrations sont déterminées par l'analyse en continu de la composition du mélange de gaz dans les ampoules à l’aide d’un catharomètre. La détermination des coefficients de diffusion et de thermodiffusion est réalisée par confrontation des relevés temporels des concentrations avec une solution analytique modélisant le transfert de matière entre deux ampoules. Les résultats sont en accord avec les résultats théoriques. Cela permet de conforter l’influence de la porosité des milieux poreux sur les mécanismes de diffusion et de thermodiffusion. / A multicomponent system, under nonisothermal condition, shows mass transfer with cross effects described by the thermodynamics of irreversible processes. The flow dynamics and convective patterns in mixtures are more complex than those of one-component fluids due to interplay between advection and mixing, solute diffusion, and thermal diffusion (or Soret effect). This can modify species concentrations of fluids crossing through a porous medium and leads to local accumulations. There are many important processes in nature and industry where thermal diffusion plays a crucial role. Thermal diffusion has various technical applications, such as isotope separation in liquid and gaseous mixtures, identification and separation of crude oil components, coating of metallic parts, etc. In porous media, the direct resolution of the convection-diffusion equations are practically impossible due to the complexity of the geometry; therefore the equations describing average concentrations, temperatures and velocities must be developed. They might be obtained using an up-scaling method, in which the complicated local situation (transport of energy by convection and diffusion at pore scale) is described at the macroscopic scale. At this level, heat and mass transfers can be characterized by effective tensors. The aim of this thesis is to study and understand the influence that can have a temperature gradient on the flow of a mixture. The main objective is to determine the effective coefficients modelling the heat and mass transfer in porous media, in particular the effective coefficient of thermodiffusion. To achieve this objective, we have used the volume averaging method to obtain the modelling equations that describes diffusion and thermodiffusion processes in a homogeneous porous medium. These results allow characterising the modifications induced by the thermodiffusion on mass transfer and the influence of the porous matrix properties on the thermodiffusion process. The obtained results show that the values of these coefficients in porous media are completely different from the one of the fluid mixture, and should be measured in realistic conditions, or evaluated with the theoretical technique developed in this study. Particularly, for low Péclet number (diffusive regime) the ratios of effective diffusion and thermodiffusion to their molecular coefficients are almost constant and equal to the inverse of the tortuosity coefficient of the porous matrix, while the effective thermal conductivity is varying by changing the solid conductivity. In the opposite, for high Péclet numbers (convective regime), the above mentioned ratios increase following a power law trend, and the effective thermodiffusion coefficient decreases. In this case, changing the solid thermal conductivity also changes the value of the effective thermodiffusion and thermal conductivity coefficients. Theoretical results showed also that, for pure diffusion, even if the effective thermal conductivity depends on the particle-particle contact, the effective thermal diffusion coefficient is always constant and independent of the connectivity of the solid phase. In order to validate the theory developed by the up-scaling technique, we have compared the results obtained from the homogenised model with a direct numerical simulation at the microscopic scale. These two problems have been solved using COMSOL Multiphysics, a commercial finite elements code. The results of comparison for different parameters show an excellent agreement between theoretical and numerical models. In all cases, the structure of the porous medium and the dynamics of the fluid have to be taken into account for the characterization of the mass transfer due to thermodiffusion. This is of great importance in the concentration evaluation in the porous medium, like in oil reservoirs, problems of pollution storages and soil pollution transport. Then to consolidate these theoretical results, new experimental results have been obtained with a two-bulb apparatus are presented. The diffusion and thermal diffusion of a helium-nitrogen and helium-carbon dioxide systems through cylindrical samples filled with spheres of different diameters and thermal properties have been measured at the atmospheric pressure. The porosity of each medium has been determined by construction of a 3D image of the sample made with an X-ray tomograph device. Concentrations are determined by a continuous analysing the gas mixture composition in the bulbs with a katharometer device. A transient-state method for coupled evaluation of thermal diffusion and Fick coefficients in two bulbs system has been proposed. The determination of diffusion and thermal diffusion coefficients is done by comparing the temporal experimental results with an analytical solution modelling the mass transfer between two bulbs. The results are in good agreement with theoretical results and emphasize the porosity of the medium influence on both diffusion and thermal diffusion process. The results also showed that the effective thermal diffusion coefficients are independent from thermal conductivity ratio and particle-particle touching.

O concreto é um dos materiais de construção civil mais versáteis, podendo se adaptar a formas diversas quando em seu estado fresco e resistindo a grandes cargas de compressão em seu estado rígido. No entanto, em estruturas mais densamente armadas ou com geometrias mais complexas, pode-se apresentar dificuldades para a moldagem, causando falhas no preenchimento da forma, o que reduz a capacidade resistente da peça e sua vida útil. Neste trabalho foi utilizado o método de partículas lagrangeanas Moving Particle Semi-Implicit (MPS) como base para um simulador para o estudo do comportamento do escoamento de pastas e argamassas cujo comportamento pode se aproximado por modelos reológicos como Bingham e Herschel-Bulkley. Foram propostos módulos para a simulação da viscosidade não-newtoniana, variação térmica no processo de cura e modelagem de turbulência. Para modelar a variação de viscosidade de um fluido não-newtoniano foi utilizado o modelo de Herschel-Bulkley. O modelo de Herschel-Bulkley possui uma singularidade para taxas de deformação muito pequenas, que resulta em valores de viscosidade infinitas, dificuldade contornada pela solução proposta por Papanastasiou (1987). Na modelagem térmica foram analisados dois modelos de dissipação, sendo um original do método e outro calculado por meio do divergente do gradiente utilizando os modelos de partículas e que teria melhores resultados para o cálculo da dissipação térmica. Também foi modelada a convecção térmica, utilizando para isso a hipótese de Boussinesq. A reação de hidratação do concreto foi modelada utilizando uma equação do tipo Hill para representar a elevação de temperatura obtida por meio um ensaio adiabático. Para complementar as simulações, foi utilizado o modelo de turbulência Detached Eddy Simulation (DES), baseado no método Large Eddy Simulation (LES), que utiliza um modelo de parede para simular a interação do fluido. Para a implementação deste modelo de turbulência foi proposto um algoritmo para o cálculo da distância da partícula de fluido à parede. Este algoritmo utiliza estruturas de dados já existentes no método de partículas de modo que sua execução requer muito menos recursos que a busca binária. Apesar do trabalho ter se guiado pela simulação do concreto fresco, que é um material particularmente complexo, outros escoamentos encontrados na engenharia civil também podem ser beneficiados pelo método, como os estudos do escoamento em sistemas prediais de água e esgoto, do escoamento e prevenção de erosão em rios e córregos, do escorregamento de encostas, dos reatores para depuração de esgotos, entre outros. / The concrete is one of the more versatile civil construction materials, it can adapt to various forms when in its fresh state while resisting to high compression loads in its rigid state. However, in some cases like densely reinforced concrete structures and complex geometry concrete structures can present issues to the casting, and failure in proper form filling can occur. These failures can reduce the resistance and the lifetime of the structure. This work used a simulator based on the lagrangean particle method called Moving Particle Semi-Implicit (MPS) to study the concrete behavior in its distinctive characteristics. Also, this work proposed modules to simulate the non-Newtonian viscosity, the thermal process of concrete cure and to model the turbulent flow. To model the variation of viscosity of a non-Newtonian fluid, the Herschel-Bulkley model, which relates the shear stress with the strain rate, was applied. The Herschel-Bulkley model has a singularity at low strain rates, which results in infinite viscosities. To overcome this issue, Papanastasiou (1987) proposed a modification in the model in order to eliminate the singularity. For the thermal modeling, two models for thermal dissipation were compared, the original method and other calculated from the divergence of gradient using the differential operators for the particle model and that could present improved results for the thermal dissipation calculation. Also, the thermal convection was modeled using the Boussinesq hypothesis. The hydration reaction of the concrete was modeled using a Hill type equation to reproduce the temperature elevation. In addition, a Detached Eddy Simulation (DES) based turbulence model with a simple wall model in the interaction of wall and fluid was applied in the simulations. To improve the turbulence model, an algorithm to calculate the distance between fluid and the nearest wall particle was proposed. The algorithm uses already calculated information from particles so that the execution requires much less resources than a binary search. Although the work has been focused on to the modeling of fresh concrete simulation, which is a particularly complex material, other flows found in civil engineering can also be benefited by the method, such as studies of drainage in water and sewage systems, drainage and prevention of erosion into rivers and streams, prevention and damage mitigation of landslides, reactors for sewage treatment among many others.

O concreto é um dos materiais de construção civil mais versáteis, podendo se adaptar a formas diversas quando em seu estado fresco e resistindo a grandes cargas de compressão em seu estado rígido. No entanto, em estruturas mais densamente armadas ou com geometrias mais complexas, pode-se apresentar dificuldades para a moldagem, causando falhas no preenchimento da forma, o que reduz a capacidade resistente da peça e sua vida útil. Neste trabalho foi utilizado o método de partículas lagrangeanas Moving Particle Semi-Implicit (MPS) como base para um simulador para o estudo do comportamento do escoamento de pastas e argamassas cujo comportamento pode se aproximado por modelos reológicos como Bingham e Herschel-Bulkley. Foram propostos módulos para a simulação da viscosidade não-newtoniana, variação térmica no processo de cura e modelagem de turbulência. Para modelar a variação de viscosidade de um fluido não-newtoniano foi utilizado o modelo de Herschel-Bulkley. O modelo de Herschel-Bulkley possui uma singularidade para taxas de deformação muito pequenas, que resulta em valores de viscosidade infinitas, dificuldade contornada pela solução proposta por Papanastasiou (1987). Na modelagem térmica foram analisados dois modelos de dissipação, sendo um original do método e outro calculado por meio do divergente do gradiente utilizando os modelos de partículas e que teria melhores resultados para o cálculo da dissipação térmica. Também foi modelada a convecção térmica, utilizando para isso a hipótese de Boussinesq. A reação de hidratação do concreto foi modelada utilizando uma equação do tipo Hill para representar a elevação de temperatura obtida por meio um ensaio adiabático. Para complementar as simulações, foi utilizado o modelo de turbulência Detached Eddy Simulation (DES), baseado no método Large Eddy Simulation (LES), que utiliza um modelo de parede para simular a interação do fluido. Para a implementação deste modelo de turbulência foi proposto um algoritmo para o cálculo da distância da partícula de fluido à parede. Este algoritmo utiliza estruturas de dados já existentes no método de partículas de modo que sua execução requer muito menos recursos que a busca binária. Apesar do trabalho ter se guiado pela simulação do concreto fresco, que é um material particularmente complexo, outros escoamentos encontrados na engenharia civil também podem ser beneficiados pelo método, como os estudos do escoamento em sistemas prediais de água e esgoto, do escoamento e prevenção de erosão em rios e córregos, do escorregamento de encostas, dos reatores para depuração de esgotos, entre outros. / The concrete is one of the more versatile civil construction materials, it can adapt to various forms when in its fresh state while resisting to high compression loads in its rigid state. However, in some cases like densely reinforced concrete structures and complex geometry concrete structures can present issues to the casting, and failure in proper form filling can occur. These failures can reduce the resistance and the lifetime of the structure. This work used a simulator based on the lagrangean particle method called Moving Particle Semi-Implicit (MPS) to study the concrete behavior in its distinctive characteristics. Also, this work proposed modules to simulate the non-Newtonian viscosity, the thermal process of concrete cure and to model the turbulent flow. To model the variation of viscosity of a non-Newtonian fluid, the Herschel-Bulkley model, which relates the shear stress with the strain rate, was applied. The Herschel-Bulkley model has a singularity at low strain rates, which results in infinite viscosities. To overcome this issue, Papanastasiou (1987) proposed a modification in the model in order to eliminate the singularity. For the thermal modeling, two models for thermal dissipation were compared, the original method and other calculated from the divergence of gradient using the differential operators for the particle model and that could present improved results for the thermal dissipation calculation. Also, the thermal convection was modeled using the Boussinesq hypothesis. The hydration reaction of the concrete was modeled using a Hill type equation to reproduce the temperature elevation. In addition, a Detached Eddy Simulation (DES) based turbulence model with a simple wall model in the interaction of wall and fluid was applied in the simulations. To improve the turbulence model, an algorithm to calculate the distance between fluid and the nearest wall particle was proposed. The algorithm uses already calculated information from particles so that the execution requires much less resources than a binary search. Although the work has been focused on to the modeling of fresh concrete simulation, which is a particularly complex material, other flows found in civil engineering can also be benefited by the method, such as studies of drainage in water and sewage systems, drainage and prevention of erosion into rivers and streams, prevention and damage mitigation of landslides, reactors for sewage treatment among many others.