L'intérêt croissant pour l'intensification des procédés a conduit à l'avènement d'un nombre conséquent de nouvelles technologies. Le projet ANR PROCIP qui a financé cette thèse a pour but de développer un logiciel d’aide à la décision pour aider l’utilisateur industriel dans son choix de technologie optimale pour une application donnée. La méthodologie globale de discrimination des technologies vis-à-vis d’un système réactif est basée sur l’utilisation d’une base de données technologique et sur le calcul de critères de choix. Elle nécessite une bonne connaissance du comportement hydrodynamique des appareils et de leurs performances en termes de transfert de chaleur et de matière. Dans cet objectif, les travaux présentés ici portent notamment sur l’étude du comportement hydrodynamique de milli-réacteurs échangeurs industriels. Des méthodologies expérimentales et numériques de caractérisation ont été mises au point. Elles ont permis d’obtenir des corrélations pour l’estimation des pertes de charge, des coefficients de dispersion axiale et des temps de mélange pour plusieurs milli-réacteurs en fonction des conditions opératoires et de la géométrie des appareils. En outre, une nouvelle méthode numérique est proposée pour la détermination des coefficients de dispersion axiale et des temps de mélange. Elle est appliquée pour prédire l’effet de l’extrapolation des caractéristiques géométriques des appareils sur ces propriétés. Dans une dernière partie, l’impact de la dispersion axiale sur le taux de conversion et la sélectivité de différents schémas de synthèses chimiques est discuté. / The interest for process intensification has leaded to the emergence of a wide panel of new technologies. The aim of the ANR PROCIP collaborative project which has funded this work is to develop a new software program including a methodology for process choice focused on intensified technologies. The global methodology of discrimination between the different technologies with respect to a given reactive system is based on the use of an equipment database and on the evaluation of criterion of choice. This methodology implies a good knowledge of the hydrodynamics of the different reactors and their mass and thermal transfer performances. The purpose of the present work is to develop experimental and numerical methodologies for the hydrodynamic characterization of different industrial milli-heat-exchangers reactors. Pressure drop, mixing time and axial dispersion coefficient correlations are given as function of the operating conditions and the geometrical parameters of the reactors. In particular, a new numerical method using CFD computation for the determination of axial dispersion coefficients and mixing times is presented. This method is used to predict the effect of the scale-up of the geometrical characteristics of an intensified reactor on its hydrodynamic performances. Finally, the impact of axial dispersion on the conversion rate and the selectivity for different chemical synthesis schemes is discussed

Made available in DSpace on 2015-05-14T16:53:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-11Bitstream added on 2015-05-14T16:58:57Z : No. of bitstreams: 1 000825412.pdf: 26718696 bytes, checksum: b6b3b9b1c7422cd74687af551ba4e14d (MD5) / Os materiais compósitos em fibra de carbono são largamente empregados no setor de transporte aéreo e vem crescendo em outros setores. Esses materiais, porém ainda apresentam susceptibilidade à delaminação, devido à baixa resistência a carregamentos fora do plano, tornando-se força motriz para a redução da vida em fadiga de compósitos laminados. Devido à importância desse tipo de dano, esta pesquisa visa entender os mecanismos que geram delaminações em compósitos tramados (biaxiais), utilizando-se o conceito energético de Griffith da mecânica da fratura linear elástica, como parâmetro de controle da delaminação. Portanto, o objetivo deste trabalho é entender a interação dos modos de propagação I e II, bem como as frações de cada modo na delaminação em fadiga axial tração-tração (denominado modo misto), em corpos de prova planos. Para isso, foram estudados os modos puros I (DCB) e II (ENF) de propagação de trinca nos compósitos processados, além de se comparar a região que delimita a propagação estável com o modo misto, o qual exigiu estudos de uma geometria apropriada para a obtenção de delaminação bem definida. Para a decomposição dos modos que agem na fadiga axial, foram aplicados critérios de falha nos dados experimentais. O ensaio de fadiga, para todos os modos de propagação, foi conduzido à razão de carga de 0,1, frequência de 5 Hz e os dados de taxa de propagação versus energia de deformação foram ajustados por uma lei empírica, previamente estudada e comparada com os mecanismos de delaminação por análise fractográfica. Os resultados mostraram que a força motriz para delaminação possui maior influência da tenacidade à fratura (GIc) e do carregamento máximo (Gmax), os quais foram adaptados na lei de Paris para delaminação estável. Para o modo misto, constatou-se que a geometri ... (Resumo completo, clicar acesso eletrônico abaixo) / Carbon fiber composite materials are currently widely employed in air transportation as structural components in Boeing 787 Dreamliner, which has around 80% (v/v) in composite. However these materials are susceptible to delamination due to low strength in through-the-thickness direction which is the driving force to reduce the fatigue life. Considering the importance of delamination, the aim of this research is to have a clear understanding of this type of damage in woven composites by using the Griffith energy approach of the linear elastic fracture mechanics as a delamination parameter. The aim of this work was to achieve insight into the interaction process of crack propagation modes I and II, and mainly to determine the mode fractions in the delamination process of tension-tension axial fatigue tests. For the mode decomposition process from axial fatigue tests, it was employed two failure criteria. In order to obtain it, the crack growth rate associated with pure modes I and II delamination were compared with the behavior of a specimen subjected to in-plane tension-tension cyclic loading that exhibits a mixed delamination mode for which needed an appropriate specimen geometry to generate a sharp delamination front. Fatigue test in all modes of propagation were conducted with a loading ratio of 0,1 and a frequency of 5 Hz. The crack growth rate versus energy release rate was described by an appropriate empirical power law which fits the experimental results and compared with delamination mechanisms observed by fractography. The results showed that the driving force for fatigue has major influence of GIc and Gmax based on the studied fractures, where both were considered in the Paris law. For the mixed mode, the geometry known as CLS had regions of crack propagation rate comparable to pure delamination modes in the stable propagation region which ... (Complete abstract click electronic access below)

abstract: Gas turbine efficiency has improved over the years due to increases in compressor pressure ratio and turbine entry temperature (TET) of main combustion gas, made viable through advancements in material science and cooling techniques. Ingestion of main combustion gas into the turbine rotor-stator disk cavities can cause major damage to the gas turbine. To counter this ingestion, rim seals are installed at the periphery of turbine disks, and purge air extracted from the compressor discharge is supplied to the disk cavities. Optimum usage of purge air is essential as purge air extraction imparts a penalty on turbine efficiency and specific fuel consumption. In the present work, experiments were conducted in a newly constructed 1.5-stage axial flow air turbine featuring vanes and blades to study main gas ingestion. The disk cavity upstream of the rotor, the 'front cavity', features a double seal with radial clearance and axial overlap at its rim. The disk cavity downstream of the rotor, the 'aft cavity', features a double seal at its rim but with axial gap. Both cavities contain a labyrinth seal radially inboard; this divides each disk cavity into an 'inner cavity' and a 'rim cavity'. Time-averaged static pressure at various locations in the main gas path and disk cavities, and tracer gas (CO2) concentration at different locations in the cavities were measured. Three sets of experiments were carried out; each set is defined by the main air flow rate and rotor speed. Each of the three sets comprises of four different purge air flow rates, low to high. The mass flow rate of ingested main gas into the front and aft rim cavities is reported at the different purge air flow rates, for the three experiment sets. For the present stage configuration, it appears that some ingestion persisted into both the front and aft rim cavities even at high purge air flow rates. On the other hand, the front and aft inner cavity were completely sealed at all purge flows. / Dissertation/Thesis / Masters Thesis Engineering 2015

La tomographie par émission de positrons est une technique d’imagerie nucléaire utilisant des noyaux radioactifs. Elle est utilisée dans le domaine clinique et préclinique. Cette dernière nécessite l’utilisation de petits animaux, comme la souris. Comme en imagerie clinique, l’objectif est d’obtenir le meilleur signal avec la meilleure précision spatiale possible. Cependant, un rapport d’échelle homme-souris suggère une résolution inférieure à 1 mm3. Un imageur conventionnel est constitué de modules de détection entourant le patient, orientés radialement. Cette approche lie efficacité et résolution spatiale. Ce travail concerne l’étude de la géométrie axiale. Les éléments de détection sont ici orientés parallèlement à l’objet. Ceci limite la corrélation entre efficacité de détection et résolution spatiale, et ainsi permet d’obtenir une haute résolution et haute sensibilité. La simulation de prototypes a permis d’envisager une résolution spatiale moyenne inférieure au millimètre et une efficacité de 15 ou 40% selon l’extension axiale. Ces résultats permettent de présager de bonnes perspectives en imageries préclinique et clinique. / Positrons emission tomography is a nuclear imaging technics using nuclear decays. It is used both in clinical and preclinical studies. The later requires the use of small animals such as the mouse. The objective is to obtain the best signal with the best spatial resolution. Yet, a weight ratio between humans and mice indicates the need of a sub-millimeter resolution. A conventional scanner is based on detection modules surrounding the object to image and arranged perpendicularly. This implies a strong relationship between efficiency and spatial resolution. This work focuses on the axial geometry in which detection modules are arranged parallel to the object. This limits the relationship between the figures of merit, leading to both high spatial resolution and efficiency. The simulations of prototypes showed great perspectives in term of sub-millimeter resolution with efficiencies of 15 or 40% according to the scanner’s axial extension. These results indicate great perspectives for both clinical and preclinical imaging.

My thesis is focused on using ICT (Information and Communication Technology) for teaching about percentage and axial symmetry. Specifically I am using an interactive whiteboard to support my teaching. The thesis is divided into two parts, a theoretical and a practical part. The first part is looking into various teaching methods, use of ICT and the interactive whiteboard in teaching in general. The second part of my thesis contains a workbook I have prepared to support my teaching on the interactive whiteboard and the application of the workbook during lessons for the students on secondary school. I have concluded my thesis with evaluation of my teaching methods and reflective practice.

O objetivo deste trabalho é calcular as vibrações forçadas de uma viga longa e fina descrita pela equação de Euler-Bernoulli com a influência de uma força axial e da carga f(t, x ). Os cálculos simbólicos são realizados utilizando a base espectral clássica, obtida a partir das raízes da equação característica , e a base dinâmica, caracterizada pelas condições iniciais impulsivas. São apresentados resultados simulados da função de Green com diversas condições de contorno e das vibrações forçadas em vigas apoiadas em uma extremidade livre, fixa, deslizante e apoiada na outra, sujeitas a ação de cargas do tipo pontuais e oscilatórias. / The objective of this work isto calculate the forced vibrations of a long and fine beam described by the equation of Euler-Bernoulli with the influence of an axial force and of the load f(t,x). The symbolic calculations are accomplished using the classical spectral basis, obtained starting from the roots of the characteristic equation, and the dynamical ba.sis, characterized by the impulsive initial conditions. Simulations for the Green function and forced vibrations are presented for a beam supported at one end and free, fastened, sliding and supported at the other end and subject to the action of punctual and oscillatory loads.

O objetivo deste trabalho é calcular as vibrações forçadas de uma viga longa e fina descrita pela equação de Euler-Bernoulli com a influência de uma força axial e da carga f(t, x ). Os cálculos simbólicos são realizados utilizando a base espectral clássica, obtida a partir das raízes da equação característica , e a base dinâmica, caracterizada pelas condições iniciais impulsivas. São apresentados resultados simulados da função de Green com diversas condições de contorno e das vibrações forçadas em vigas apoiadas em uma extremidade livre, fixa, deslizante e apoiada na outra, sujeitas a ação de cargas do tipo pontuais e oscilatórias. / The objective of this work isto calculate the forced vibrations of a long and fine beam described by the equation of Euler-Bernoulli with the influence of an axial force and of the load f(t,x). The symbolic calculations are accomplished using the classical spectral basis, obtained starting from the roots of the characteristic equation, and the dynamical ba.sis, characterized by the impulsive initial conditions. Simulations for the Green function and forced vibrations are presented for a beam supported at one end and free, fastened, sliding and supported at the other end and subject to the action of punctual and oscillatory loads.

O proposito deste trabalho é apresentar uma metodologia para projeto de uma turbina axial para micro aproveitamentos hidráulicos com ênfase no projeto das geometrias do rotor e distribuidor, incluindo os resultados analíticos e numéricos através do método dos painéis. Comparações do projeto analítico com testes de campo são também apresentadas. A metodologia analítica utilizada foi a teoria do escoamento não-viscoso de Wenig que avalia os fatores de interferência para modelar o quanto as características de sustentação e arrasto de uma cascata de perfis são relacionadas com as de um perfil isolado. Foi verificado que a teoria de Wenig fornece uma boa previsão do fator de interferência se o ângulo de ataque for relativamente baixo e a espessura das pás for relativamente pequena quando comparada com a distância entre as pás. A metodologia numérica usando o método de vorticidade superficial proposto por Martensen para uma cascata de perfis e para um perfil isolado foi utilizada para se ter uma comparação com os coeficientes analíticos de sustentação e arrasto. Testes de campo foram realizados em um protótipo de 20 kW de acordo com a norma IEC-60041 e sua comparação com o método analítico e por consequência o método numérico validou o método empregado para confecção das pás do rotor e distribuidor. / The purpose of this work is to present a methodology to design a small axial hydraulic turbine with emphasis on the project of the profiles of the runner and wicket gate, including both analytical and numerical results from a cascade panel method. Comparisons with field test measurements of a prototype are also presented. The analytical methodology used is the Wenigs inviscid flow theory which requires the evaluation of interference factors to model how lift and drag characteristics of the turbine cascade of blades are related to those of a single isolated airfoil. It is found that the Wenigs theory provides a reasonable prediction of the lift interference factor if both the angle of attack is relatively low and the thickness of the blades is relatively small when compared to the distance between the blades. The numerical methodology that relies the Hess and Smiths 2-D panel method for a cascade of blades and for an isolated airfoil was used in order to have a comparison with the analytical lift and drag. Prototype field test measurements of the turbine power output, in agreement with IEC-60041 standards, were carried out to evaluate the results using the analytical and numerical methods.

Como conseqüência do atual desenvolvimento tecnológico dos materiais aço e concreto, várias pesquisas têm surgido com vistas a um melhor aproveitamento da capacidade desses dois materiais, exigindo um maior conhecimento sobre o comportamento dos elementos, inclusive sobre sua vulnerabilidade a estados limites últimos. Sendo a instabilidade um estado limite último possível de ocorrer em configurações de equilíbrio de peças de concreto armado submetidas a determinadas solicitações normais, seu estudo torna-se fundamental para que seja possível propor soluções estruturais seguras e economicamente viáveis. Este trabalho apresenta a análise de alguns aspectos que interferem no estudo da estabilidade de pilares esbeltos de concreto armado, através de uma abordagem envolvendo aspectos teóricos, como também aspectos práticos oriundos da resolução de exemplos. O estudo é feito com base nos métodos geral e do equilíbrio, com os processos exato e do pilar padrão, através de um software (SISTEMA FLEXOR), desenvolvido por CADAMURO Jr. (1997). O objetivo é testar a viabilidade desses métodos a fim de propor soluções e, com isso, tornar mais amplo e acessível o uso de pilares esbeltos de concreto armado, incentivando a adoção de projetos mais arrojados sem subutilização dos materiais. / As a consequence of the actual technological development of the materials steel and concrete, many researches have come up with proposal of better use of these two materials capacity, demanding a bigger knowledge about the behaviour of the elements, included your vulnerability to ultimate limit states. Being the instability a possible ultimate limit state of reinforced concrete columns equilibrium configuration, this study has been fundamental to make possible to propose safe and economically reasonable structural solutions. This work presents the analysis of some aspects that interfere in the study of slender reinforced concrete columns stability, through an approach involving theoretical and practical aspects derived from numerical solutions. The scheme is based in the General and Equilibrium Methods with the Exact Process and Model Column Method, through a software (SISTEMA FLEXOR) developed by CADAMURO Jr. (1997). The objective is to testify the practicability of these methods, to propose solutions and to render wider and more practical the use of slender reinforced concrete columns, stimulating the adoption of projects bolders without underutilisation of the materials.

Submitted by Marcele Costal de Castro (costalcastro@gmail.com) on 2017-09-27T18:55:51Z No. of bitstreams: 1 ROGERIO CHAFFIN NUNES D.PDF: 1775171 bytes, checksum: 6c9663bc03e326ae36a3c1663a42812c (MD5) / Made available in DSpace on 2017-09-27T18:55:51Z (GMT). No. of bitstreams: 1 ROGERIO CHAFFIN NUNES D.PDF: 1775171 bytes, checksum: 6c9663bc03e326ae36a3c1663a42812c (MD5) Previous issue date: 2006-04 / Neste trabalho a equação de transferência radiativa bidimensional é resolvida numericamente considerando-se projeções no eixo axial, a aproximação axial, para os casos com meio isotrópico e ansiotrópico. Resolver esse problema necessita-se de uma formulação matemática que aproxime angularmente a equação de transferência radiativa por um método de ordenadas discretas, resultado dessa operação é um sistema de equações diferenciais parciais de 1ª ordem com condições de contorno prescritas no fluxo incidente que é aproximado por uma malha de pixels, que são obtidos com a utilização de uma base natural e a sua solução numérica se dá através de um processo iterativo denominado método de aproximações sucessivas. Investiga-se a sensibilidade do fluxo emergente, considerando as propriedades de absorção e espalhamento do meio e apresenta-se os resultados numéricos da influência dessas propriedades no mapeamento do fluxo incidente-emergente considerando-se um meio não homogêneo.