Final thesis, elaborated within the master study field of Foundry technology, deals with determination of some parameters of ceramic foam filters that are necessary for using numerical simulation during foundry practice. Thesis foccuses on defining methodology, manufacturing messuring device and measuring pressure drop on several type sof ceramic foam filters in dependence on flow rate of measuring medium. Measuring medium selected is water, mening this thesis deals also with water simulation in foundry technology.

The decaying plasma was studied by the optical emission spectroscopy. DC discharge created at 45 – 200 mA in Pyrex and Quartz tubes in flowing regime was used. The emission of three nitrogen spectral systems (1st and 2nd positive and 1st negative) were studied in time evolution for pressures of 500 – 5 000 Pa at two wall temperatures – ambient and liquid nitrogen (150 K inside the decaying plasma). Results showed that all three nitrogen systems (respectively N2(B, v), N2(C, v) and N2+(B, v) states as their origins) had their population maxima called pink-afterglow in the afterglow part. These maxima decreased with the increase of pressure for all systems, and moved to the later decay time. Maxima increased with discharge current (respectively power) and moved to shorter time. Populations at temperature of 150 K were measured due to the experimental arrangement from 17 ms, only, and thus pink aftergow maximum wasn’t observed (only at 5 000 Pa some maximum was recognized). Populations were smaller at 150 K that populations measured at laboratory temperature at the middle decay time (50-100 ms). At the late time, the populations were higher at lower temperature at lower pressure. Higher shifts (in intensity and decaytime) of pink afterglow maxima were observed in Quartz tube in comparison with their values in Pyrex tube. Besides the populations, rotational temperatures of selected bands of three observed spetral systems (for 1st negative 0-0 band, 1st positive 2-0 band and for 2nd positive 0-2 band) were measured. Rotational temperatures were monitored from presumption that this kind of temperature is equal to temperature of neutral gas (at local thermodynamic equilibrium). Results from 1st negative and 1st positive system showed strong decreasing of rotational temperatures up to about 10 ms at post-discharge begin, then temperatures were constant up to 20 ms of decay time and after that they grew up. Temperatures increased with the increase of current. The part with decreased temperature correlated with pink-afterglow part of post-discharge. Unfortunately, rotational temperatures of 2nd positive system had bad reproducibility and the time profile shape was opposite. Experimental results were compared with numerical kinetic model created by group of prof. Vasco Guerra at Instituto Supetior Técnico in Portugal. Several sets of conditions for simulation at 500 and 1 000 K in active discharge were applicable for the calculation corresponding to the experiment. Comparison of numerical simulation and experimental data done for N2(B) state demonstrated that maxima populations in pink afterglow are depended on the temperature difference between active discharge and post discharge. Maxima populations were supposed in pink afterglow disappeared if the same temperatures in active and post discharges were supposed. Temperature in active discharge is higher at higher apllied power, as it was showed from rotational temperatures observation. The results clearly showed that real temperature profile must be included into the kinetic model.

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Cette thèse propose une méthodologie pour des études en simulation numérique en grande dimension. Elle se décline en différentes étapes : construction de plan d'expériences approprié, analyse de sensibilité et modélisation par surface de réponse. Les plans d'expériences adaptés à la simulation numérique sont les "Space Filling Designs", qui visent à répartir uniformément les points dans l'espace des variables d'entrée. Nous proposons l'algorithme WSP pour construire ces plans, rapidement, avec de bons critères d'uniformité, même en grande dimension. Ces travaux proposent la construction d'un plan polyvalent, qui sera utilisé pour les différentes étapes de l'étude : de l'analyse de sensibilité aux surfaces de réponse. L'analyse de sensibilité sera réalisée avec une approche innovante sur les points de ce plan, pour détecter le sous-ensemble de variables d'entrée réellement influentes. Basée sur le principe de la méthode de Morris, cette approche permet de hiérarchiser les variables d'entrée selon leurs effets. Le plan initial est ensuite "replié" dans le sous-espace des variables d'entrée les plus influentes, ce qui nécessite au préalable une étude pour vérifier l'uniformité de la répartition des points dans l'espace réduit et ainsi détecter d'éventuels amas et/ou lacunes. Ainsi, après réparation, ce plan est utilisé pour l'étape ultime : étude de surfaces de réponse. Nous avons alors choisi d'utiliser l'approche des Support Vector Regression, indépendante de la dimension et rapide dans sa mise en place. Obtenant des résultats comparables à l'approche classique (Krigeage), cette technique semble prometteuse pour étudier des phénomènes complexes en grande dimension. / This thesis proposes a methodology of study in numeric simulation for high dimensions. There are several steps in this methodology : setting up an experimental design, performing sensitivity analysis, then using response surface for modelling. In numeric simulation, we use a Space Filling Design that scatters the points in the entire domain. The construction of an experimental design in high dimensions must be efficient, with good uniformity properties. Moreover, this construction must be fast. We propose using the WSP algorithm to construct such an experimental design. This design is then used in all steps of the methodology, making it a versatile design, from sensitivity analysis to modelling. A sensitivity analysis allows identifying the influent factors. Adapting the Morris method principle, this approach classifies the inputs into three groups according to their effects. Then, the experimental design is folded over in the subspace of the influent inputs. This action can modify the uniformity properties of the experimental design by creating possible gaps and clusters. So, it is necessary to repair it by removing clusters and filling gaps. We propose a step-by-step approach to offer suitable repairing for each experimental design. Then, the repaired design is used for the final step: modelling from the response surface. We consider a Support Vector Machines method because dimension does not affect the construction. Easy to construct and with good results, similar to the results obtained by Kriging, the Support Vector Regression method is an alternative method for the study of complex phenomena in high dimensions.

[pt] A superfície da terra é formada por processos geológicos que geram as rochas, assim como por processos naturais de degradação e de erosão. A erosão destrói as estruturas que compõem o solo e seu transporte é feito pela ação da água da chuva, do vento, da gravidade e até do gelo. A origem e evolução das bacias sedimentares, dentre outros fenômenos, é estudada pela geologia sedimentar, a qual trata do estudo dos processos físicos, químicos e biológicos atuantes na superfície da terra desde o seu início até os dias atuais. Na atualidade, o uso de modelos que permitem analisar processos de escoamento superficial, desprendimento de partículas e de transporte e deposição de sedimentos em bacias hidrográficas é cada vez mais frequente. O uso e análise desses modelos demonstra que, para escalas relativamente pequenas e áreas não muito extensas, o rebaixamento do perfil dos rios está diretamente ligado aos processos de deformação tectônica. Por outro lado, modelos de previsão de evolução do relevo associados com intemperismo, erosão e deposição de sedimentos, considerando escalas espaciais do tipo regional ou continental e escalas de tempo relativamente grandes (maior que 10(5) anos) devem ser desenvolvidos acoplando tanto efeitos tectônicos como morfológicos. Neste trabalho é apresentado um modelo computacional que permite analisar a evolução na mudança do relevo de bacias hidrográficas, em pequena e grande escala, assim como estimar a produção de sedimento resultante do processo erosivo. O algoritmo de análise é escrito na linguagem de programação Cmais mais e considera a simulação de diferentes cenários, que incluem deformação tectônica, processos de encosta (difusão e movimentos de massa) e processos de incisão fluvial, dando-se particular atenção à formação e evolução da rede fluvial de drenagem. Para a análise de resultados, o programa oferece a visualização 3D de diferentes superfícies: distribuição dos sedimentos, evolução da rede fluvial, mudanças topográficas do relevo, etc. / [en] The surface of the earth is formed by geological processes that originate the rocks, as well as for natural processes of degradation and erosion. The erosion destroys the soil structures and the transport of sediments is made by the action of the rain water, wind, gravity and, in some cases, ice. The origin and evolution of sedimentary basins, amongst other phenomena, are studied by the sedimentary geology, which deals with the analysis of physical, chemical and biological processes that act directly on earth surface since its origin until the current days. Nowadays, the use of runoff - erosion models that analyze processes such as detachment of particles and transport and deposition of sediment in drainage basins is every time more frequent. The use of these models demonstrates that, for relatively small scales and not very extensive areas, relief changes are directly related to tectonic processes. On the other hand, landscape evolution models and associated weathering, erosion and deposition with parameterization for regional or continental spatial scales and large time scales (more than 10(5) years), must be developed to adequately couple tectonics and geomorphology. Is presented in this work a computational model to analyze the landscape evolution in hydrographic basins, considering small and large scales, as well as evaluate the production of sediment resultant of the erosive process. The algorithm is written in the programming language C++ and considers the simulation of different scenes, that include tectonics, hillslope processes (diffusion and landslides) and bedrock incision, giving particular attention to the channel network evolution. For the analysis process the program offers the visualization of different 3D surfaces: sediment distribution, drainage network, topographical relieves etc.