Orientador: Jorge Roberto Pimentel / Banca: Marcos Antonio Sanches Vieira / Banca: Ricardo Egydio de Carvalho / Resumo: O resfriamento de produtos agrícolas, em ambientes com atmosfera controlada, é uma das técnicas que tem sido utilizada por produtores e indústrias do setor, sendo importante se ter informações sobre a influência de parâmetros que atuam durante o processo. Neste trabalho, foi desenvolvido um modelo numérico unidimensional usando-se um método explícito de aproximação das derivadas de equações diferenciais por diferenças finitas, para solucionar a equação da condução de calor em sólidos com alto teor de água e de formato cilíndrico, que estejam submetidos a um fluxo de ar resfriado. Utilizando o modelo, simulou-se a influência de variáveis físicas e geométricas na distribuição das temperaturas radiais em cilindros hipotéticos, obtendo-se resultados coerentes com o comportamento previsto para tal situação. Foram feitas medidas experimentais das temperaturas em diferentes localizações radiais em alguns vegetais com formato aproximadamente cilíndrico e, os resultados dessas medidas, comparados com as previsões numéricas, revelando boa concordância dentro da faixa do erro experimental. / Abstract: Cooling in atmosphere controlled environment is one of the methods used in the food preservation and processing industry. For best process improvement information, for example, concerning the influence of different parameters on the internal temperature values are of interest. The present work deals with a simple numeric model developed using a explicit finite-differences scheme for solve the one-dimensional cylindrical transient heat equation. The equation is solved with a field temperature inicial condition, simetry center boundary condition and a pure convection surface boundary condition after normalizing the equation system. A FORTRAN program was develop to solve the resulting matricial system to obtain the transient radial temperature distribution as a function of convective heat coefficient, Fourier number, thermal diffusivity and Biot number. The experimental setup consisted of a retangular duct througt witch cooled air circulated by a blower. Inside the duct fresh approximated cylindrical shapped samples of food products have they radial temperature measured in four different location using iron-constantan thermocouples. The results show that there is a good a agreement between the experimentally measured temperature values and that computed using numeric model. / Mestre

Made available in DSpace on 2014-06-11T19:25:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-07-30Bitstream added on 2014-06-13T20:53:33Z : No. of bitstreams: 1 massoni_pr_me_rcla.pdf: 268207 bytes, checksum: 6e94a8d273c83e316e9da0bdfcaea8a1 (MD5) / O resfriamento de produtos agrícolas, em ambientes com atmosfera controlada, é uma das técnicas que tem sido utilizada por produtores e indústrias do setor, sendo importante se ter informações sobre a influência de parâmetros que atuam durante o processo. Neste trabalho, foi desenvolvido um modelo numérico unidimensional usando-se um método explícito de aproximação das derivadas de equações diferenciais por diferenças finitas, para solucionar a equação da condução de calor em sólidos com alto teor de água e de formato cilíndrico, que estejam submetidos a um fluxo de ar resfriado. Utilizando o modelo, simulou-se a influência de variáveis físicas e geométricas na distribuição das temperaturas radiais em cilindros hipotéticos, obtendo-se resultados coerentes com o comportamento previsto para tal situação. Foram feitas medidas experimentais das temperaturas em diferentes localizações radiais em alguns vegetais com formato aproximadamente cilíndrico e, os resultados dessas medidas, comparados com as previsões numéricas, revelando boa concordância dentro da faixa do erro experimental. / Cooling in atmosphere controlled environment is one of the methods used in the food preservation and processing industry. For best process improvement information, for example, concerning the influence of different parameters on the internal temperature values are of interest. The present work deals with a simple numeric model developed using a explicit finite-differences scheme for solve the one-dimensional cylindrical transient heat equation. The equation is solved with a field temperature inicial condition, simetry center boundary condition and a pure convection surface boundary condition after normalizing the equation system. A FORTRAN program was develop to solve the resulting matricial system to obtain the transient radial temperature distribution as a function of convective heat coefficient, Fourier number, thermal diffusivity and Biot number. The experimental setup consisted of a retangular duct througt witch cooled air circulated by a blower. Inside the duct fresh approximated cylindrical shapped samples of food products have they radial temperature measured in four different location using iron-constantan thermocouples. The results show that there is a good a agreement between the experimentally measured temperature values and that computed using numeric model.

As part of a continued research project for the Utah Water Research Laboratory and the State of Utah, a study of flow measurement devices is being conducted throughout the state. Initially the project included only measurement devices associated with high-risk dams, but has since been broadened to any measurement structure of interest for water users in the state. The physical dimensions, relative elevations, and flow accuracy were documented for each included device. After visiting sixteen sites, it was found that fourteen of the measuring devices had incorrect geometries. Of these fourteen, thirteen of them were originally Parshall flumes. A large percentage of Parshall flumes with geometry inaccuracies was also found from previous data collected for this project. One reoccurring issue was that the flumes had not been well maintained and had damage to the walls or floor. Some of these Parshall flumes did not have a diverging downstream section and are referred to as Montana flumes. In these cases, a standard Parshall rating curve was used to determine flow where it did not apply. Some of the flumes that were tested operated regularly under submerged conditions, and no adjustments were made for submergence. The objective of this research is to determine if Montana flumes (Parshall flumes without a diverging section) operate similarly to fully constructed Parshall flumes under both free-flow and submerged conditions. Laboratory tests were performed in the Utah Water Research Laboratory to determine corrections for submergence. Flow 3D, a computational fluid dynamics (CFD) software program, was also used to develop corrections for a submerged Montana flume. The laboratory results were compared to the computational fluid dynamics results. By using Flow 3D, a reliable numerical process was developed to determine the flow rate in a submerged Montana flume in an effort to expand the results to other seized flumes.

Le développement récent du transport ferroviaire a conduit à une forte augmentation du trafic durant la dernière décennie, augmentation qui devrait sepoursuivre dans la décennie à venir avec les futurs développements de ce mode de transport. L'augmentation du trafic se traduit pour l'infrastructure par une augmentation des sollicitations subies par les voies ferrées. La qualité des voies ferrées est garante de la performance du mode de transport ferroviaire,mais également de la sécurité des matériels roulants et des usagers de l'infrastructure. Conserver la qualité du réseau ferré est donc une priorité pour les gestionnaires d'infrastructures ferroviaires. Le ballast ferroviaire a pour rôle de répartir les efforts induits par la circulation des trains et d'assurer la bonne géométrie de l'infrastructure. La surveillance de la dégradation du ballast est donc primordiale pour assurer la qualité del'infrastructure.L'objectif de cette thèse est de proposer un outil numérique permettant d'anticiper la dégradation et le comportement d'une infrastructure ferroviaire sous trafic. Cet outil doit permettre de simuler efficacement lecomportement du ballast ferroviaire sous un grand nombre de cycles de chargements mobiles.Une première partie détaille la composition des infrastructures ferroviaires, précise les rôles du ballast et identifie les grandes lignes de son comportement.Il est fait le choix d'utiliser une méthode de représentation du ballast par élément fini et un modèle de comportement élastoplastique. Le ballast est alors traité comme un géomatériau continu répondant à des lois de comportementélastoplastique.Dans une seconde partie, les bases de la modélisation élastoplastique sont rappelées. Puis, plusieurs modèles de comportement issus de la littérature et comportant des éléments intéressants sont identifiés et étudiés.Dans une troisième partie, un nouveau modèle de comportement frottant compactant est proposé. Il est composé d’un critère nouveau et d'une loi d'écoulement originale. Enfin, le modèle est complété par la prise encompte, de la dégradation du matériau via une diminution de l'angle de frottement interne.Dans une quatrième partie, les méthodes stationnaires sont rappelées. Ces méthodes sont spécifiquement développées pour la modélisation des problèmes incluant des charges en mouvement. Les différents algorithmes sont implémentés àl'aide d'un code de calcul développé dans le logiciel Matlab et à l'aide du logiciel d'éléments finis COMSOL Multiphysics. En particulier, la méthode stationnaire à double échelle de temps, qui est un développement nouveau, permet la modélisation rapide d'un grand nombre de cycles de chargements et la prise en compte des effets d'usure du matériau.Dans une dernière partie, les deux principaux modèles tridimensionnels utilisés sont présentés. Sur un faible nombre de cycles de chargements, divers résultats sont établis selon les différents modèles de comportement utilisé. Sur un très grand nombre de cycles de chargements, les résultats obtenus montrent l'évolution des déformations irréversibles de la structure et de la dégradation du matériau. / Recent development in rail transportation has led traffic increasing during last decade, an increase which should continue in next decade due to the future developments of railway transport. Traffic growing induces infrastructure's solicitation increasing. Railways quality is warrant of rail transport performance, but also ensure security of the rolling stock and safety of the infrastructure users. Maintaining quality of the rail network is major priority for railway infrastructure managers. Purpose of rail ballast is to distribute load of the moving trains and to ensure track geometry. Monitoring of ballast degradation is therefore essential to ensure the quality of the infrastructure.The aim of this thesis is to develop a numerical tool to anticipate the degradation and behaviour of a railway infrastructure under traffic. This tool is intended to effectively simulate the behaviour of railway ballast under numerous mobile loads cycles.A first part details the composition of railway infrastructures, specifies roles of the ballast and identifies the main lines of its behaviour.Choice is made to use finite element method to represent the ballast and an elastic-plastic behaviour model. The ballast is then treated as a continuous geomaterial responding to elastic-plastic behaviour. Therefore, in a second part, the basics of elastic-plastic modelling are exposed. Then, several existing behaviours models which present interesting elements are identified and studied.In a third part, a new behaviour model, called "frottant-compactant" is presented. It is composed with a new criterion and an original flow rule. Finally, the model is completed by taking account of materials degradation via internal friction angle decreasing.In a fourth part, the steady-states methods are exposed. These methods are specifically developed for modelling problems including moving loads. Different algorithms are implemented using Matlab coding software and using the finites elements method software COMSOL Multiphysics. Principally, the double time-scale steady-state method, newly developed, allow rapid modelling of numerous loading cycles and representation of material wear effects.In a final part, the two three-dimensional models used are presented. On a few loading cycles, various results are established depending on different behaviour models. On a very large number of load cycles, the results obtained show the evolution of plastic strains in the structure and the degradation of the material.

Este trabalho teve por finalidade simular a hidrodinâmica da Plataforma Continental Interna do Estado de São Paulo (PCISP) e da Plataforma Continental Média do Estado de São Paulo (PCMSP) no período de verão, em resposta às forçantes do gradiente de densidade, do vento climatológico e das marés, através da implementação do modelo numérico hidrodinâmico tridimensional Regional Ocean Modeling System (ROMS). Os experimentos realizados mostraram que os efeitos da distribuição de densidade sobre o comportamento geral da circulação na PCISP e PCMSP são secundários quando comparados à circulação induzida pela tensão de cisalhamento do vento. Os resultados apontam que na PCISP e na PCMSP a componente de velocidade paralela à costa é dominada por forçantes de frequência subinercial, como o vento climatológico e o gradiente de densidade, enquanto que a componente normal, na direção normal à costa, é fortemente influenciada pela forçante de maré. / The aim of this study was simulate the hydrodynamic of the Inner Continental Shelf of the State of São Paulo (PCISP) and of the Mid Continental Shelf of the State of São Paulo (PCMSP) during summer, in response to the density gradient forcing, to the climatological wind shear stress forcing and to the tide forcing, applying the tridimensional hydrodynamic numeric model Regional Ocean Modeling System (ROMS). The experiments performed showed the effects of the density distribution over the general circulation behavior in the PCISP and PCMSP are secondary compared with the induced climatological wind shear stress circulation. The results indicate that in the PCISP and in the PCMSP the component velocity parallel to the coast is dominated by subinertial frequencies forcing, as the climatological wind and the density gradient, while the component velocity perpendicular to the coast is strongly influenced by the tide forcing.

Este trabalho teve por finalidade simular a hidrodinâmica da Plataforma Continental Interna do Estado de São Paulo (PCISP) e da Plataforma Continental Média do Estado de São Paulo (PCMSP) no período de verão, em resposta às forçantes do gradiente de densidade, do vento climatológico e das marés, através da implementação do modelo numérico hidrodinâmico tridimensional Regional Ocean Modeling System (ROMS). Os experimentos realizados mostraram que os efeitos da distribuição de densidade sobre o comportamento geral da circulação na PCISP e PCMSP são secundários quando comparados à circulação induzida pela tensão de cisalhamento do vento. Os resultados apontam que na PCISP e na PCMSP a componente de velocidade paralela à costa é dominada por forçantes de frequência subinercial, como o vento climatológico e o gradiente de densidade, enquanto que a componente normal, na direção normal à costa, é fortemente influenciada pela forçante de maré. / The aim of this study was simulate the hydrodynamic of the Inner Continental Shelf of the State of São Paulo (PCISP) and of the Mid Continental Shelf of the State of São Paulo (PCMSP) during summer, in response to the density gradient forcing, to the climatological wind shear stress forcing and to the tide forcing, applying the tridimensional hydrodynamic numeric model Regional Ocean Modeling System (ROMS). The experiments performed showed the effects of the density distribution over the general circulation behavior in the PCISP and PCMSP are secondary compared with the induced climatological wind shear stress circulation. The results indicate that in the PCISP and in the PCMSP the component velocity parallel to the coast is dominated by subinertial frequencies forcing, as the climatological wind and the density gradient, while the component velocity perpendicular to the coast is strongly influenced by the tide forcing.

Afin de permettre l’utilisation de hautes fréquences dans le domainedu chauffage par induction industriel, l’emploi d’inducteurs multibrins est envisagé.Or, les pertes occasionnées dans ces inducteurs peuvent être importantes etdépendent fortement de leur géométrie interne qui est complexe. Pour faciliter laconception d’inducteurs multibrins à faibles pertes, il est nécessaire d’en comprendrele comportement électromagnétique. Dans cette thèse, nous présentons ledéveloppement d’un logiciel de calcul parallèle dévolu à la modélisation électromagnétique3D d’inducteurs multibrins. Nous décrivons une méthode originale deconstruction de la géométrie des inducteurs. Ce logiciel est basé sur une méthodenumérique de type intégrale ayant l’avantage de ne pas nécessiter le maillage desespaces entre les brins. L’emploi du calcul parallèle est une des grandes forces de celogiciel. Les études réalisées montrent l’impact de la géométrie sur le comportementde ce type d’inducteur. / In order to enable to use high frequencies in the domain of the industrialinductive heating, the use of multi-wires inductors is considered. But, lossesoccurring into that inductors can be important and strongly depend on their complexinternal geometry. To facilitate the design of lossless multi-wires inductors, it isnecessary to under stand their electromagnetic behavior. In this thesis, we presentthe development of a software of parallel computation intended to the 3D electromagneticmodeling of multi-wires inductors. We describe an original method ofbuilding of the geometry of that inductors. This software is based on an integralmethod in which the meshing of spaces between the wires is unnecessary. The useof parallel computing is one of the great forces of this software. The studies werealized show the impact of the geometry on the behavior of that type of inductor.

Made available in DSpace on 2015-02-24T19:48:45Z (GMT). No. of bitstreams: 1 MariaFAM_TESE_Capa_ate_pag45.pdf: 2486179 bytes, checksum: 1280b90e85a5ab287bf116c2bf019536 (MD5) Previous issue date: 2013-11-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This thesis presents the results of application of SWAN Simulating WAves Nearshore numerical model, OF third generation, which simulates the propagation and dissipation of energy from sea waves, on the north continental shelf at Rio Grande do Norte, to determine the wave climate, calibrate and validate the model, and assess their potential and limitations for the region of interest. After validation of the wave climate, the results were integrated with information from the submarine relief, and plant morphology of beaches and barrier islands systems. On the second phase, the objective was to analyze the evolution of the wave and its interaction with the shallow seabed, from three transverse profiles orientation from N to S, distributed according to the parallel longitudinal, X = 774000-W, 783000-W e 800000-W. Subsequently, it was were extracted the values of directional waves and winds through all the months between november 2010 to november 2012, to analyze the impact of these forces on the movement area, and then understand the behavior of the morphological variations according to temporal year variability. Based on the results of modeling and its integration with correlated data, and planimetric variations of Soledade and Minhoto beach systems and Ponta do Tubar?o and Barra do Fernandes barrier islands systems, it was obtained the following conclusions: SWAN could reproduce and determine the wave climate on the north continental shelf at RN, the results show a similar trend for the measurements of temporal variations of significant height (HS, m) and the mean wave period (Tmed, s); however, the results of parametric statistics were low for the estimates of the maximum values in most of the analyzed periods compared data of PT 1 and PT 2 (measurement points), with alternation of significant wave heights, at times overrated with occasional overlap of swell episodes. By analyzing the spatial distribution of the wave climate and its interaction with the underwater compartmentalization, it was concluded that there is interaction of wave propagation with the seafloor, showing change in significant heights whenever it interacts with the seafloor features (beachrocks, symmetric and asymmetric longitudinal dunes, paleochannel, among others) in the regions of outer, middle and inner shelf. And finally, it is concluded that the study of the stability areas allows identifications of the most unstable regions, confirming that the greatest range of variation indicates greater instability and consequent sensitivity to hydrodynamic processes operating in the coastal region, with positive or negative variation, especially at Ponta do Tubar?o and Barra do Fernandes barrier islands systems, where they are more susceptible to waves impacts, as evidenced in retreat of the shoreline / Esta tese apresenta os resultados da aplica??o do modelo num?rico SWAN Simulating WAves Nearshore, de terceira gera??o, que a simula propaga??o e dissipa??o da energia das ondas do mar, na plataforma continental setentrional do Rio Grande do Norte, com vista a determinar o clima de ondas, calibrar e validar o modelo e aferir suas potencialidades e limita??es para a regi?o de interesse. Ap?s a valida??o do clima de ondas os resultados foram integrados com as informa??es do relevo submarino e morfologia em planta dos sistemas de praias e ilhas barreiras. Nesta segunda fase, o objetivo foi analisar a evolu??o da onda e sua intera??o com o fundo marinho raso a partir de tr?s perfis transversais de orienta??o de N para S, distribu?dos conforme as paralelas longitudinais, X = 774000-W, 783000-W e 800000-W. Posteriormente, extra?ram-se os valores direcionais de ondas e ventos ao longo de todos os meses compreendidos entre novembro de 2010 a novembro de 2012, para analisar a incid?ncia destas for?antes sobre a movimenta??o de ?rea para entender o comportamento das varia??es morfol?gicas de acordo com a variabilidade temporal anual. Com base nos resultados da modelagem e da sua integra??o com os dados correlacionados e das varia??es planim?tricas dos sistemas praiais de Soledade e Minhoto e das ilhas barreiras Ponta do Tubar?o e Barra do Fernandes, obteve-se as seguintes conclus?es: o SWAN conseguiu reproduzir e determinar o clima de ondas para o litoral setentrional do RN, os resultados mostram tend?ncia semelhante com as medidas nas varia??es temporais de altura significativa (HS, m) e per?odo m?dio de onda (Tmed, s), entretanto, os resultados param?tricos das estat?sticas mostraram-se baixos para as estimativas dos valores m?ximos, na maioria dos per?odos analisados em compara??o os dados do PT 01 e PT 02 (pontos de medi??o), com altern?ncia das alturas significativas de ondas, em alguns momentos sobrestimado com a sobreposi??o ocasional de epis?dios de ondula??o. Ao analisar a distribui??o espacial do clima de ondas e sua intera??o com a compartimenta??o submarina, concluiu-se que h? intera??o da propaga??o da onda com o fundo, evidenciando altera??o nas alturas significativas sempre quando esta interage com as fei??es de fundo (rochas praiais, dunas longitudinais sim?tricas e assim?tricas, paleocanal, dentre outros) existentes nas regi?es das zonas da plataforma externa, m?dia e interna. E finalmente notou-se que especialmente as ilhas de Ponta do Tubar?o e Barra do Fernandes, est?o mais sujeitas a incid?ncia das ondas, causando o recuo da linha de costa; o estudo das ?reas de estabilidade permitiu identificar as regi?es mais inst?veis, corroborando com o senso de que a maior amplitude de varia??o indica maior instabilidade e consequente sensibilidade aos processos hidrodin?micos atuantes na regi?o costeira, seja esta varia??o positiva ou negativa

De nos jours, la modélisation numérique constitue un outil indispensable pour le prototypage de convertisseurs électromagnétiques. Les matériaux magnétiques jouent un rôle essentiel dans la conversion de l’énergie, il est donc nécessaire de maîtriser leur comportement et leur représentation. L’objectif de ce travail s’inscrit dans ce cadre et s’attache à élaborer des lois réalistes de comportement de matériaux afin de les inclure dans des simulateurs de circuits. Concernant le comportement statique, le modèle de Jiles-Atherton a été implémenté puis adapté, simplifié et modifié afin d’en améliorer la précision et l’implémentation. La modélisation dynamique du matériau a été effectuée grâce au modèle DWM élaboré au laboratoire Ampère. Ce modèle intègre les effets dynamiques excédentaires grâce à une loi « dynamique de matériau » implémentée au sein de l’équation de diffusion magnétique. Ce modèle a été ensuite homogénéisé afin d’en améliorer son implémentation future dans un simulateur de circuit. Chacun des différents modèles a été testé et validé sur plusieurs échantillons. / Nowadays, numerical modeling is an indispensable tool for the prototyping of electromagnetic converters. Magnetic materials play an essential role into the energy conversion so it is necessary to control their behavior as well as their modeling. The objective of this work is to develop realistic laws of material behavior for circuit simulators use. Regarding the static behavior, the Jiles-Atherton model has been implemented and adapted, simplified and modified to improve accuracy and implementation. Dynamic modeling of the material was performed using the model DWM developed into the Ampere laboratory. This model incorporates the excedentary dynamic effects thanks to a "dynamical material law" implemented into the magnetic diffusion equation. Then this model was homogenized to improve its future implementation in a circuit simulator. Each of the different models has been tested and validated on several samples.