La tesis tiene la finalidad de establecer la manufacturabilidad de un veh��culo anfibio que pueda ser de uso com��n (civil), ya que la mayor��a de estos veh��culos son de uso militar. Se utiliza un veh��culo de R/C con motor de combusti��n para simular lo que ser��an los cambios a realizar en un veh��culo real, en este caso en espec��fico se toma una Humvee (H1) como el veh��culo real. Los requerimientos de primera instancia que se necesitaron para poder desarrollar este proyecto fueron varios; primero fue la elecci��n de los veh��culos el de R/C y el real, despu��s se prosigui�� con el dise��o de la carrocer��a, continuamos con el dise��o del sistema de flotaci��n y se vieron las posibles opciones del sistema propulsi��n. Despu��s de dise��ar y construir se prosigui�� a implementar todos los sistemas antes mencionados. Por ultimo se realizaron las pruebas necesarias y se sacaron los costos de los sistemas implementados a tama��o real para poder aplicar las modificaciones al veh��culo real..

El objetivo principal de esta investigaci��n fue la evaluaci��n de espec��ficas herramientas de corte dentro del taller mec��nico de LuK Puebla para tres diferentes procesos de mecanizado, mediante la aplicaci��n de los par��metros de corte implementados actualmente y con la finalidad de analizar el desgaste de los filos en el maquinado de acero D2. La evaluaci��n se realiz�� en base a una comparativa de herramientas de distintos fabricantes en conjunto con la elaboraci��n de pruebas de rendimiento apropiadas para cada proceso, desarrolladas conforme a la informaci��n recabada de las herramientas seleccionadas y bajo espec��ficos par��metros de corte. Durante el desarrollo de la investigaci��n se pudo observar la importancia que representa la evaluaci��n del desgaste en las herramientas dentro de las operaciones de mecanizado, as�� como los elementos que influyen en su aplicaci��n. / (cont.) Fue posible apreciar los diferentes puntos de vista que se han empleado en evaluaciones de torneado, fresado y taladrado, dentro de las investigaciones desarrolladas por los fabricantes de herramientas y personal especializado en el estudio del rendimiento de dichos elementos. En la observaci��n y medici��n del desgaste se presentaron algunas limitaciones producto del equipo utilizado para esta investigaci��n, pero en base al desarrollo y los recursos disponibles en el ��rea, se idearon elementos por medio de los cuales se pudo llevar a cabo la inspecci��n de las herramientas de corte probadas. Con la aplicaci��n del dise��o de experimentos y el an��lisis estad��stico realizado con Minitab��, se obtuvo un an��lisis de resultados propio a cada operaci��n de corte, para definir cuales de los factores seleccionados para la evaluaci��n influyen m��s en el rendimiento de las herramientas. Finalmente se evaluaron los beneficios econ��micos de las pruebas y algunas mejoras para favorecer el desarrollo del mecanizado de alto rendimiento. .

Shewanella spp. are model electroactive bacteria (EAB) and well-known for their broad metabolic capabilities and extracellular electron transfer (EET) properties, which allow them to utilize a diverse range of carbon substrates, such as formate, lactate, pyruvate, and amino acids. However, the majority of Shewanella spp. cannot metabolize glucose, a naturally occuring carbon and energy source. Here, we examine the electrode respiring potential of Shewanella chilikensis JC5T- and its coexistence with acetoclastic EAB, Geobacter sulfurreducens in glucose-fed microbial electrolysis cells (MECs) operated at a set anode potential condition of 0 V vs. Ag/AgCl. Chronoamperometry analysis revealed that the maximum current density was 0.04523 mA/cm2 (CE: 14.55%) in S-MEC (only S. chilikensis JC5T) and 0.299 mA/cm2 (CE: 53.85%) in CC-MEC (S. chilikensis JC5T and G. sulfurreducens) which is 6.6-folds higher in current density and 3.7-folds higher in coulombic efficiency than S-MEC. Cyclic voltammetry analysis demonstrates presence of biofilm and redox mediator for EET mechanisms. Metabolic analysis showed that S. chilikensis as a monoculture and co-culture with G. sulfurreducens can metabolize glucose and produce intermediates such as acetate, formate, and lactate. These intermediates are likely used to generate electrical current. Collectively, these results provide novel insights on electrode respiring properties of S. chilikensis and its coexistence with acetoclastic EAB, G. sulfurreducens to enhance the current density and coulombic efficiency from glucose-fed MEC.

Materiais enrijecidos são encontrados cotidianamente na engenharia, como na construção de aeronaves, veículos, navios e manufaturas diversas. Na Engenharia Civil, são exemplos de materiais enrijecidos o concreto armado e o solo reforçado. A solução aproximada para esse tipo de problema pode ser encontrada pelo uso de métodos numéricos como o Método dos Elementos Finitos (MEF) e o Método dos Elementos de Contorno (MEC). Particularmente, o MEC é muito vantajoso em casos onde se tem elevados gradientes de tensão, como em problemas da mecânica da fratura, além de modelar de forma natural meios infinitos, sendo muito utilizado na análise de interação solo-estrutura ou de túneis. No entanto, como no MEC somente o contorno é discretizado, torna-se necessária a utilização de um acoplamento numérico para que o efeito mecânico dos enrijecedores seja considerado. Para esse acoplamento, podem ser utilizados diversos métodos numéricos, sendo neste trabalho realizado com o MEF e o MEC em sua forma unidimensional (MEC 1D). Dentro desse contexto, o acoplamento com o MEC 1D destaca-se por vantagens, como a compatibilidade dos métodos e a redução de aproximações. Com isso, este trabalho tem como principal objetivo o desenvolvimento e comparação de soluções numéricas para o problema de domínios enrijecidos, no âmbito do MEC aplicado a problemas bidimensionais. Os enrijecedores foram considerados como elementos de treliça, sendo realizado inicialmente na sua forma mais usual, modelando-os por meio do MEF. A seguir foi implementada nova formulação para o acoplamento, na qual os enrijecedores são modelados por meio do MEC 1D. A implementação do MEC 1D foi validada pela comparação de resultados com soluções analítica e do programa computacional FTOOL. No caso do acoplamento, os resultados de ambas formulações foram comparados com resposta do programa computacional ANSYS. Foram avaliados quatro exemplos, sendo dois isotrópicos e dois anisotrópicos. Foram aplicadas diferentes condições de carregamentos, apoios e materiais, sendo utilizadas diversas discretizações e graus de aproximação nos enrijecedores. Verificou-se os efeitos da mudança do grau de aproximação, mantendo-se constante o número de graus de liberdade. Os resultados obtidos foram similares às respostas do ANSYS, foram mecanicamente equivalentes, não havendo diferença relevante em custo computacional. O acoplamento com o MEC 1D levou a resultados estáveis e, em geral, melhores do que com o MEF. No caso de aproximação quadrática, o acoplamento com o MEF frequentemente levou a resultados instáveis. Com o aumento do grau de aproximação, os resultados de ambos métodos se aproximam, se tornando muito próximos com aproximação do quarto grau. Verificou-se que próximo às pontas dos enrijecedores ocorrem concentrações de tensão, havendo maior influência da discretização e grau de aproximação adotado nestas áreas. / The reinforced materials are commonly encountered in engineering applications, as in the construction of airplanes, vehicles, ships and general manufactures. In Civil Engineering, the reinforced concrete and the reinforced soil are examples of reinforced materials. The solution of this kind of problem can be found by the use of numerical methods as the Finite Element Method (FEM) and the Boundary Element Method (BEM). Particularly, the BEM use in cases with high stress gradients, such as in fracture mechanics problems, is very advantageous. The BEM models infinite domains in a natural way, being largely used in analysis as soil-structure interaction and tunnel modelling. However, as in the BEM only the boundary is discretized, became necessary the use of a numerical coupling to consider the mechanical effect of the stiffeners. For the coupling many numerical methods can be used, in this study it was realized with the FEM and with the BEM in its unidimensional way (BEM 1D). In this context, the coupling BEM/BEM 1D stands out for its advantages, like the compatibility between the methods and the reduction of approximations. Therefore, the main objective of this study is the development and the comparison of numerical solutions for reinforced media problems, considering the framework of the bidimensional BEM problems. The coupling was implemented considering the stiffeners as truss elements, initially it was implemented in the most usual way, by modelling the stiffeners through the FEM. In the following, a new coupling formulation was proposed, in which the stiffeners are modelled through the BEM 1D method. The BEM 1D implementation was validated by comparing the results with analytical and numerical solutions, the last one obtained with the software FTOOL. Both coupling strategies were compared with the solution obtained by the software ANSYS. Four examples were evaluated, with two isotropic and two anisotropic domains. Different boundary conditions, supports and materials were applied, as many discretization and the approximation degree of the stiffeners were tested. The effects of changing the approximation degree in both coupling strategies keeping the degrees of freedom constant were analysed. The results obtained with the implemented algorithms were mechanically coherent, and they were similar to ANSYS results. For all examples, there is no significant computational costs differences between the two coupling strategies. However, the coupling with the BEM 1D leaded to more stable results and better approximations. It was observed that the MEF results were instable for many results, mainly in the quadratic approximations. When the approximation degree rises, the methods tend to converge to equivalent results, becoming very close in fourth degree approximation. Lastly, it was observed stress concentration in the stiffeners ends. In these regions, the discretization and the approximation degree have large influence to the numerical response.

Materiais enrijecidos são encontrados cotidianamente na engenharia, como na construção de aeronaves, veículos, navios e manufaturas diversas. Na Engenharia Civil, são exemplos de materiais enrijecidos o concreto armado e o solo reforçado. A solução aproximada para esse tipo de problema pode ser encontrada pelo uso de métodos numéricos como o Método dos Elementos Finitos (MEF) e o Método dos Elementos de Contorno (MEC). Particularmente, o MEC é muito vantajoso em casos onde se tem elevados gradientes de tensão, como em problemas da mecânica da fratura, além de modelar de forma natural meios infinitos, sendo muito utilizado na análise de interação solo-estrutura ou de túneis. No entanto, como no MEC somente o contorno é discretizado, torna-se necessária a utilização de um acoplamento numérico para que o efeito mecânico dos enrijecedores seja considerado. Para esse acoplamento, podem ser utilizados diversos métodos numéricos, sendo neste trabalho realizado com o MEF e o MEC em sua forma unidimensional (MEC 1D). Dentro desse contexto, o acoplamento com o MEC 1D destaca-se por vantagens, como a compatibilidade dos métodos e a redução de aproximações. Com isso, este trabalho tem como principal objetivo o desenvolvimento e comparação de soluções numéricas para o problema de domínios enrijecidos, no âmbito do MEC aplicado a problemas bidimensionais. Os enrijecedores foram considerados como elementos de treliça, sendo realizado inicialmente na sua forma mais usual, modelando-os por meio do MEF. A seguir foi implementada nova formulação para o acoplamento, na qual os enrijecedores são modelados por meio do MEC 1D. A implementação do MEC 1D foi validada pela comparação de resultados com soluções analítica e do programa computacional FTOOL. No caso do acoplamento, os resultados de ambas formulações foram comparados com resposta do programa computacional ANSYS. Foram avaliados quatro exemplos, sendo dois isotrópicos e dois anisotrópicos. Foram aplicadas diferentes condições de carregamentos, apoios e materiais, sendo utilizadas diversas discretizações e graus de aproximação nos enrijecedores. Verificou-se os efeitos da mudança do grau de aproximação, mantendo-se constante o número de graus de liberdade. Os resultados obtidos foram similares às respostas do ANSYS, foram mecanicamente equivalentes, não havendo diferença relevante em custo computacional. O acoplamento com o MEC 1D levou a resultados estáveis e, em geral, melhores do que com o MEF. No caso de aproximação quadrática, o acoplamento com o MEF frequentemente levou a resultados instáveis. Com o aumento do grau de aproximação, os resultados de ambos métodos se aproximam, se tornando muito próximos com aproximação do quarto grau. Verificou-se que próximo às pontas dos enrijecedores ocorrem concentrações de tensão, havendo maior influência da discretização e grau de aproximação adotado nestas áreas. / The reinforced materials are commonly encountered in engineering applications, as in the construction of airplanes, vehicles, ships and general manufactures. In Civil Engineering, the reinforced concrete and the reinforced soil are examples of reinforced materials. The solution of this kind of problem can be found by the use of numerical methods as the Finite Element Method (FEM) and the Boundary Element Method (BEM). Particularly, the BEM use in cases with high stress gradients, such as in fracture mechanics problems, is very advantageous. The BEM models infinite domains in a natural way, being largely used in analysis as soil-structure interaction and tunnel modelling. However, as in the BEM only the boundary is discretized, became necessary the use of a numerical coupling to consider the mechanical effect of the stiffeners. For the coupling many numerical methods can be used, in this study it was realized with the FEM and with the BEM in its unidimensional way (BEM 1D). In this context, the coupling BEM/BEM 1D stands out for its advantages, like the compatibility between the methods and the reduction of approximations. Therefore, the main objective of this study is the development and the comparison of numerical solutions for reinforced media problems, considering the framework of the bidimensional BEM problems. The coupling was implemented considering the stiffeners as truss elements, initially it was implemented in the most usual way, by modelling the stiffeners through the FEM. In the following, a new coupling formulation was proposed, in which the stiffeners are modelled through the BEM 1D method. The BEM 1D implementation was validated by comparing the results with analytical and numerical solutions, the last one obtained with the software FTOOL. Both coupling strategies were compared with the solution obtained by the software ANSYS. Four examples were evaluated, with two isotropic and two anisotropic domains. Different boundary conditions, supports and materials were applied, as many discretization and the approximation degree of the stiffeners were tested. The effects of changing the approximation degree in both coupling strategies keeping the degrees of freedom constant were analysed. The results obtained with the implemented algorithms were mechanically coherent, and they were similar to ANSYS results. For all examples, there is no significant computational costs differences between the two coupling strategies. However, the coupling with the BEM 1D leaded to more stable results and better approximations. It was observed that the MEF results were instable for many results, mainly in the quadratic approximations. When the approximation degree rises, the methods tend to converge to equivalent results, becoming very close in fourth degree approximation. Lastly, it was observed stress concentration in the stiffeners ends. In these regions, the discretization and the approximation degree have large influence to the numerical response.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-02-29T22:23:18Z No. of bitstreams: 1 GladstoneDeAlencarAlves_TESE.pdf: 2879555 bytes, checksum: 499f63f27c15ad2e8aa5781274c7a911 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-03-01T23:49:08Z (GMT) No. of bitstreams: 1 GladstoneDeAlencarAlves_TESE.pdf: 2879555 bytes, checksum: 499f63f27c15ad2e8aa5781274c7a911 (MD5) / Made available in DSpace on 2016-03-01T23:49:08Z (GMT). No. of bitstreams: 1 GladstoneDeAlencarAlves_TESE.pdf: 2879555 bytes, checksum: 499f63f27c15ad2e8aa5781274c7a911 (MD5) Previous issue date: 2014-09-12 / Os modelos de caminhada aleat?ria com correla??o temporal (ou seja, mem?ria) t?m despertado o interesse para o estudo sobre difus?o an?mala. A caminhada aleat?ria e suas generaliza??es v?m ocupando um lugar de destaque na caracteriza??o de fen?menos f?sicos, qu?micos e biol?gicos. A correla??o temporal ? um fator necess?rio neste modelos para provocar difus?o an?mala. Os modelos que apresentam correla??es temporais de longo-alcance s?o denominados genuinamente de n?o-Markovianos, caso contr?rio, de curto-alcance, Markovianos. Dentro deste contexto, fizemos uma revis?o dos modelos j? existentes que apresentam correla??o temporal, isto ?, mem?ria total, modelo de caminhada do elefante, ou mem?ria parcial, modelo de caminhada com alzheimer e o modelo com mem?ria com perfil gaussiano. Percebe-se que esses modelos apresentaram superdifus?o, expoente de Hurst (H > 1/2). Estudamos neste trabalho um modelo de caminhada aleat?ria superdifusivo com mem?ria exponencialmente decrescente. Esse parece ser um resultado contradit?rio, uma vez que, ? bem conhecido que a caminhada aleat?- ria com correla??es que decaem exponencialmente pode ser aproximada arbitrariamente bem por um processo Markoviano e que o teorema do limite central pro?be superdifus?o quando a vari?ncia do tamanho dos passos for finita. Nossa proposta para resolver o aparente paradoxo parte do princ?pio de que o modelo exponencial seja genuinamente n?o-Markoviano, devido a constante de decaimento da exponencial ser dependente de tempo. Finalmente, discutimos ideias para futuras investiga??es. / The random walk models with temporal correlation (i.e. memory) are of interest in the study of anomalous diffusion phenomena. The random walk and its generalizations are of prominent place in the characterization of various physical, chemical and biological phenomena. The temporal correlation is an essential feature in anomalous diffusion models. These temporal long-range correlation models can be called non-Markovian models, otherwise, the short-range time correlation counterparts are Markovian ones. Within this context, we reviewed the existing models with temporal correlation, i.e. entire memory, the elephant walk model, or partial memory, alzheimer walk model and walk model with a gaussian memory with profile. It is noticed that these models shows superdiffusion with a Hurst exponent H > 1/2. We study in this work a superdiffusive random walk model with exponentially decaying memory. This seems to be a self-contradictory statement, since it is well known that random walks with exponentially decaying temporal correlations can be approximated arbitrarily well by Markov processes and that central limit theorems prohibit superdiffusion for Markovian walks with finite variance of step sizes. The solution to the apparent paradox is that the model is genuinely non-Markovian, due to a time-dependent decay constant associated with the exponential behavior. In the end, we discuss ideas for future investigations.

Epithelial cell adhesion to the surrounding extracellular matrix (ECM) is necessary for their proper behaviour and function. During pregnancy and lactation mammary epithelial cells (MECs) require signals imparted by specific β1 integrin-laminin interactions for their functional differentiation in response to Prolactin (Prl) and for the correct formation of polarised secretory acini. Downstream of β1 integrin (β1Itg), the scaffold protein Integrin Linked Kinase (ILK) has been identified as the key signal transducer that is required for both Prl driven lactational differentiation and the establishment of apico-basal polarity in MECs. ILK is a multifunctional adaptor protein that links integrins to the actin cytoskeleton and Rho GTPases such as Rac1. ILK forms a ternary IPP (ILK-PINCH-Parvin) complex with PINCH and Parvins, which are central to its adaptor functions. However, it is not known which of ILKs interacting partners are important for controlling tissue-specific gene expression, or what acts downstream of the IPP complex. In this thesis I have now established that inducible ILK deletion in MECs from ILKfl/flCreER mice, prevents phosphorylation of Stat5 leading to a failure of Prl induced milk expression. In addition I have established a 3-dimensional culture model using the EpH4 mammary epithelial cell line, which respond to Prl treatment and form polarised acini similar to primary cells. In these cells knocking down β1Itg and ILK by lentiviral shRNA delivery was confirmed to have a profound effect on β-Casein production. Expression of ILK mutants that disrupt its protein-protein interactions, showed that mutation of K220 and E359 in the kinase domain also reduced milk production. This means that ILKs kinase domain is important for MEC differentiation, and suggests that Parvin binding (which is disrupted by these mutations) is key in mediating ILKs differentiation functions. Using a complimentary shRNA approach, knockdown of the βParvin binding Rac guanine nucleotide exchange factor αPix also prevented MEC differentiation. This identified for the first time that αPix is required for differentiation and suggests a route by which ILK, via it’s interaction with Parvin, can link integrins to αPix and Rac activity. Interestingly, αPix depletion did not disrupt the IPP complex or polarity, suggesting that αPix represents a differentiation specific bifurcation point in β1Itg-ILK adhesive signalling. Together, this work has helped to establish how ILK is involved in MEC differentiation and has identified a new role for the downstream Rac GEF αPix. In addition, this work contributes to our understanding of the molecular mechanisms by which cell adhesion regulates fundamental cell biological behaviours.

[pt] A introdução de solventes orgânicos em espectrômetros com plasma indutivamente acoplado (ICP) representa uma limitação à confiabilidade dos resultados pela incidência de efeitos de matriz. Estratégias de calibração como Standard Dilution Analysis (SDA) e Multi-energy Calibration (MEC) propõem contornar as interferências de matriz, reduzindo o tempo de análise, o consumo de reagentes e a geração de resíduos. Na SDA com dois padrões internos (IS), a aquisição do sinal é feita ao longo do tempo durante a mistura de duas soluções analíticas: uma formada por 50 % de amostra + 50 por cento de solução-padrão contendo os analitos e um IS (S1) e outra formada por 50 por cento de amostra + 50 por cento do branco e um segundo IS (S2). Já na calibração por MEC, que também utiliza duas soluções similares à SDA, porém, sem IS, mede-se simultaneamente sinais dos elementos em diferentes comprimentos de onda. Estes métodos foram aplicados para a determinação de Ca, K, Mg, Na, P, Si e S em amostras de biodiesel diluídas em xileno, por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES) e comparados com as calibrações por adição de analito (SA) e padronização interna (IS). Os limites de quantificação não apresentaram diferença significativa em relação aos métodos tradicionais, variando de 0,05 mg kg-1 (Ca) a 1,4 mg kg-1 (Na) para SDA e de 0,01 mg kg-1 (Mg) a 0,98 mg kg-1 (P) para MEC. A veracidade foi verificada através de testes de recuperação em amostras de biodiesel e no material padrão de referência NIST 1084a (Wear metals in lubricating oil), com recuperações de 101 ± 6 por cento para SDA e de 108 ± 8 por cento para MEC. A estabilidade do sinal analítico a longo prazo e os menores impactos econômicos e ambientais fazem a SDA e a MEC interessantes para a determinação elementar em amostras de biodiesel e óleo diluídas em xileno. / [en] Direct introduction of organic solvents into inductively coupled plasma (ICP) spectrometers represents a limitation to reliability of the results due to matrix effects. Different calibration methods, such as Standard Dilution Analysis (SDA) and Multi-energy Calibration (MEC) have been proposed to overcome this kind of interference, reducing analysis time, reagent consumption and waste generation. In SDA with two internal standards (IS), the signal is acquired over time during the mixing process of two analytical solutions: one consisting of 50 percent of sample + 50 percent of analytical standards and IS1 (S1) and the other consisting of 50 percent of sample + 50 percent of blank solution and IS2 (S2). In MEC calibration, which also uses two solutions similarly to SDA, but without IS, signals from the elements are measured simultaneously at different wavelengths. These methods were applied to the determination of Ca, K, Mg, Na, P, Si and S in biodiesel samples diluted in xylene by inductively coupled plasma optical emission spectrometry (ICP OES) and compared to calibrations by standard addition (SA) and internal standardization (IS). Limits of quantification showed no statistically significant difference compared to the traditional methods, whereas the limits found by SDA ranged from 0.05 mg kg-1 (Ca) to 1.4 mg kg-1 (Na) for SDA, and from 0.01 mg kg-1 (Mg) to 0.98 mg kg-1 (P) for MEC. The trueness was verified through recovery tests on biodiesel samples and the standard reference material NIST 1084a (Wear metals in lubricating oil), with recoveries of 101 ± 6 percent for SDA and 108 ± 8 percent for MEC. Long-term signal stability and lower economic and environmental impacts places SDA and MEC as an interesting strategy for elemental determination in biodiesel and oil samples diluted in xylene.

Purpose: The purpose of our research was to study the role and impact that ‘information and communication technologies’ and the MEC centers might have on the Uruguayan society. We want to examine how MEC and ICT usage could affect daily lives of marginalized people in Uruguay. We want to explore how it might benefit individuals living in small communities by evaluating indicators of positive impact of how ICT usage could strengthen capitals and increase freedom. Furthermore, our aim is to understand how digital literacy and the access to ICT’s can be related to democracy, and try to understand if greater individual empowerment also could enhance democracy. Method: For a period of eight weeks, from March 3rd to 28th of April 2014, we were in Montevideo and vicinity to gather material that we later have analyzed qualitatively. The material is based on observations in the field, interviews with various stakeholders, manuals and national policy documents concerning MEC, as well answers we received from an online survey. Main conclusions:We have found that the MEC centers and ICT, combined with education, could be an important tool to facilitate the inclusion of marginalized groups in the Uruguayan society. Our findings indicate that the MEC centers in Uruguay could contribute to the decentralization of the country and have a positive impact on gender- and generation equality. The result suggests that the centers could have a positive impact on democracy in Uruguay by teaching participants how to use e-governmental services as well as encouraging them to participate in online governmental websites. Furthermore, we found that MEC lets the local communities be in charge of their own development, which indicate that the sustainability of the project is increased as well as the positive development outcome. Through the MEC centers we found that both the freedom and the social capital of the participants were positively affected.

Made available in DSpace on 2015-04-14T13:59:07Z (GMT). No. of bitstreams: 1 457571.pdf: 10390298 bytes, checksum: e0a909718de3206b7518ce4a359dd921 (MD5) Previous issue date: 2014-03-31 / Gravity currents begin when two fluid bodies, with different densities, collides one against other, starting a relative movement in both. This currents are called polydisperses when the excess in density is due to the presence of more than one type of particles, which are characterized by their diameter, diluted in dispersant phase. The purpose of this research is to investigate, using Direct Numerical Simulation (DNS), how different combinations of fine and coarse particles affect the dynamics of the current when two different boundary conditions are imposed on the bottom wall of the domain. There is also interest, using 3D simulation, in investigate how the main tri-dimensional structures influences in its dynamics. Data of an experimental work are used to validate and compare the results for the final deposit profile and front evolution of the current. The suspended mass and complete energy budget are also presented. Two-dimensional simulations showed that the addition of a small amount of fine particles, into a current predominantly composed by coarse particles, affect more significantly the features of the flow than the opposite. Comparisons show us the inability of the two-dimensional simulation to reproduce accurately the intense turbulence generated in 3D, resulting an error in the dissipation term due to convective motion. / Correntes de gravidade tem in?cio quando corpos fluidos de diferentes densidade se encontram, dando in?cio ? um movimento relativo entre ambos. Estas correntes s?o ditas poli-dispersas quando o excesso na densidade acontece pela presen?a de mais de uma fra??o granulom?trica, caracterizadas pelo di?metro da part?cula, dilu?das na fase dispersante. A inten??o desta pesquisa ? investigar, atrav?s da Simula??o Num?rica Direta (DNS), como a combina??o de diferentes propor??es iniciais de duas fra??es granulom?tricas, uma dita mais fina e a outra dita mais grossa, afeta a din?mica da corrente. Outro ponto investigado ? o comportamento da corrente quando imp?e-se, na parede inferior do dom?nio de c?lculo, duas condi??es de contorno diferentes: a) fluxo de part?culas atrav?s do fundo; b) fluxo nulo de part?culas atrav?s do fundo. Busca-se tamb?m, atrav?s de simula??o 3D, determinar como as principais estruturas tridimensionais influenciam nesta din?mica. Utilizam-se os resultados de um trabalho experimental para validar e comparar os resultados obtidos para o perfil de dep?sito e evolu??o da frente da corrente. A quantidade de massa suspensa e o balan?o completo de energias s?o apresentados. Atrav?s de simula??es 2D foi poss?vel mostrar que a adi??o de pequenas quantidades de part?culas finas, em uma corrente predominantemente composta por part?culas grossas, afeta mais as caracter?sticas do escoamento do que o contr?rio. Compara??es mostram a incapacidade da simula??o bidimensional reproduzir, de forma precisa, a intensa turbul?ncia gerada em uma simula??o tridimensional, o que resulta em erros na estimativa da perda dissipativa devida ao movimento convectivo.