<p>An accurate understanding of the respiratory fluid dynamics is instrumental for medical applications, such as drug delivery system and treatment of diseases. Substantial research has been done to study such flow. However, a great number of these studies have the prevailing assumption of having a smooth wall, in despite the human trachea and bronchi is sustain by a series of cartilaginous rings, which creates height differences near the wall. To study the effect of including cartilaginous rings in the respiratory flow we developed two experiments, presenting a comparison between a smooth model and a model with cartilaginous rings. First, we present an experimental observation of a simplified Weibel-based model of the human trachea and bronchi with cartilaginous rings. The experiments were carried out with a flow rate comparable with a resting state (trachea-based Reynolds number of Re_D = 2650). In the second experiment, we developed a similar experiment but in a model with a tracheal stenosis (70% in the middle of the model) and no bronchi. In this case we increase the Reynolds number to Re_D= 3350, still a resting breathing state condition.</p> <p>For both experiments, we used transparent models and refractive index-matching methods were used to observe the flow, particularly near the wall. The flow was seeded with tracers to perform particle image velocimetry and particle tracking velocimetry to quantify the effect the rings have on the flow near the trachea and bronchi walls. From the results, we present a previously unknown phenomenon in the cavities between the cartilaginous rings: a small recirculation is observed in the upstream side of the cavities throughout the trachea. This recirculation is due to the adverse pressure gradient created by the expansion, which traps particles within the ring cavity. In addition, we found that the cartilaginous rings induce velocity fluctuations into the flow, which enhances the near-wall momentum of the flow reducing the separation after the stenosis. Size of the recirculation is reduced by 11% and the maximum upstream velocity is reduced by 38%, resulting in a much weaker recirculation because of the rings. Also noticed a delay in the separation from the trachea to bronchi bifurcation. </p> <p>The detection of recirculation zones in the cartilage ring cavities and the perturbation sheds light on the particle deposition mechanism and helps explain results from previous studies that have observed an enhancement of particle deposition in models with cartilage rings. The results highlight the importance to include the cartilaginous rings in respiratory flow studies. Finally, we compared the results from the stenotic case with Reynolds-averaged Navier-Stokes (RANS) models (k – ε, k – ε RNG, k – ω, k – ω SST, k – ω SST LRN and 4-equation Transition SST). In the results, indicate significant discrepancies between the experimental measurements and the simulations, mainly in the area with flow separation after the contraction. Therefore, RANS algorithms should not be considered reliable for research purposes in respiratory fluid dynamics without experimental validation. </p>

The impact of swirl (i.e., flow with axial and azimuthal velocity components) on the turbulent flow in a pipe is studied using two-component laser-Doppler velocimetry (LDV). There are practical motivations for the flow geometry. For example, previous studies demonstrate that introducing swirl in the tube bank of a paper machine headbox can significantly increase mixing, and hence increase fiber dispersion and orientation isotropy in the finished paper product. The flow characteristics in a pipe downstream of a single straight tapered fin, a single fin with 180??ist but otherwise identical geometry, and four twisted fins were therefore studied at a pipe-based Reynolds number of 80,000. Radial profiles of the mean and rms fluctuations of the streamwise and azimuthal velocity components are measured; results for the straight and twisted single fin are compared to determine the effects of fin geometry and swirl on the turbulent wake downstream of the fin. From a practical viewpoint, it is also desirable to have adjustable swirl, where swirl can either be turned on or off depending upon the type of paper product being produced. The next generation swirler concept consists of fins fabricated from two-way shape memory alloys. Using the two-way memory effect, the fins will be in their straight configuration when cold and twisted configuration (hence acting as a swirler) when hot. This study is the initial phase in developing new active control mechanisms, known as the Vortigen concept, for increasing productivity, and hence reducing wasted raw material and energy, in the pulp and paper industry.

The role of energy in wealth and development is evident but the manner that a population’s access to energy effects overall growth is unclear. Understanding the role of energy in society can impact policies to push improvement in underdeveloped countries. Therefore, it is necessary to know how energy improves quality of life and what improvements need to be made to provide the necessary resources to underdeveloped populations. The first half of the thesis focuses on the role of energy use in society and its effect on human development. It is established that underdeveloped countries are in fact positively affected from increased energy access. Additionally, that the use of renewables will improve all the aspects of human development: health, wealth, and education. These results suggest that policy makers should focus on increasing clean energy in developing countries to also improve overall development. The second half shifts to the design and characterization of a water tunnel and the role it has in understanding fluid flow for near-wall visualization. Using refractive index matching (RIM) this experimental method can be used to study micro-surfaces that could improve efficiency in transportation or renewable energy. The water tunnel herein can achieve turbulent flows, unlike previous RIM designs.

There are many different techniques to display 3D information. However, not many of them are able to provide sufficient depth cues to the observers to sense or feel the images as real three-dimensional objects. Volumetric three-dimensional displays generate images within a real 3D space, so they provide most of the depth cues automatically. This thesis discusses the basic notions required to understand three-dimensional displays. Also discussed are different techniques used to display 3D information and their advantages and disadvantages as well as their current limitations. Several rare-earth doped fluoride crystals that are excited to emit visible light by sequential two photon absorption have been investigated as display medium candidates for static volumetric three dimensional displays. A scalable display medium is suggested to enable large 3D displays. This medium is a dispersion of particles of the rare earth doped fluoride crystals in a refractive index-matched polymer matrix. Detailed experiments are described to prepare such a scalable display medium using a wide variety of polymers. The scattering problem in such a medium was greatly reduced by index-matching the polymer to the crystalline particles. An index-matching condition that optimizes the performance was identified and demonstrated. A potential near-future solution is demonstrated and improvements are suggested.

No description available.

The purpose of this work is to test the feasibility of using particle image velocimetry(PIV) for measurements of flow through a porous medium, more specifically in this casea rotating bed reactor S3. The results from experiments preformed can then be usedto validate and improve computational fluid dynamics models. The report presentsdifferent possible combinations of solids and fluids for refractive index matchingand tests some velocity limits of the optical equipment used. PIV appears to be apromising method for measuring flow through a porous medium. The theoreticallimit due to motion blur is an angular velocity of around 3800 RPM, and the actualtested lower bound for this limit is 453 RPM.

Ce travail est financé par le fond européen Interreg VA (projet "PowderReg"). L'optimisation du transport, du stockage et du mélange des dispersions granulaires passe par le contrôle de leur écoulement, par exemple en ajoutant des vibrations mécaniques. Ce travail permet d'apporter une meilleure compréhension de l'influence des vibrations sur la rhéologie apparente de dispersions granulaires modèles dans le régime quasi-statique. Des travaux expérimentaux et numériques sont réalisés afin de sonder les modifications de la dynamique locale ainsi que les hétérogénéités qui apparaissent lors de leur mise en écoulement. Deux géométries présentant des intérêts fondamentaux, géophysiques et industriels sont étudiées : la cellule de type Couette et le plan incliné. Dans un premier temps, des mesures iso-indice couplées à de la fluorescence induite par laser ont été réalisées sur des suspensions granulaires dans une cellule de type Couette sous vibrations. Les vibrations rendent la rhéologie locale en homogénéisant le système. Elles suppriment la contrainte seuil apparente et font apparaître un plateau Newtonien à bas gradient, intrinsèque à la dynamique locale qui est de nature diffusive. Il est apparu que le temps de réarrangement des particules, dépendant de l'intensité des vibrations, est relié au volume libre disponible autour de chaque particule. L'étude numérique de cette géométrie dans le cas d'une dispersion granulaire sèche a mis en évidence des résultats similaires. Dans un second temps, des écoulements de dispersions de grains secs sur un plan incliné vibrant ont été réalisés. Des travaux numériques sur cette même géométrie ont permis d'enrichir cette étude. Les résultats mettent en évidence l'existence de deux régimes sous vibrations. Le comportement dans le régime dominé par la gravité n'est pas influencé par les vibrations, et un profil de Bagnold est observé. Les vibrations permettent principalement de baisser la friction basale, influant alors la hauteur des dépôts. Dans le régime dominé par les vibrations, les écoulements sont déclenchés par les vibrations elles-mêmes. Il est apparu qu'elles induisent des fluctuations de vitesses, qui créées alors une température granulaire. Cette température permet d'activer les réorganisations à l'échelle de la particule, éliminant le seuil apparent responsable du blocage des écoulements et permettant leur contrôle au travers du taux de cisaillement / This work is funded by the European Founds Interreg VA ("PowderReg" project). The optimization of the transport, storage and mixture of granular dispersions involves their flow control, by adding mechanical vibrations, for example. The present work enables a better understanding of the influence of the vibrations on the apparent rheology of model granular dispersions in the quasi-static regime. Experimental and numerical studies were carried out in order to probe the modifications of the local dynamic and heterogeneities that appear during the flow. Two geometries, interesting for diverse applications in fundamental science, geophysics and industries, were studied: the Couette cell geometry and the inclined plane. In the first step, refractive-index matching technique, coupled to the planar laser induced fluorescence was used to make measurements in granular suspensions in a vibrated Couette cell geometry. Vibrations make the rheology local by homogenizing the system. They suppress the yield stress and result in the appearance of a Newtonian plateau at the low shear, intrinsic to the local dynamic, which is diffusive in nature. It appears that the rearrangement time of the particles, depending on the intensity of the vibrations, is linked to a free volume available around each particle. The numerical study of this geometry in the case of a dry granular dispersion shows similar results. In the second step, flows of dry granular dispersions down the inclined and vibrated plane were realized. This study was completed with a numerical work. The results demonstrated the existence of two distinct regimes under vibrations. The behavior in the gravity-driven regime is not affected by the vibrations and a Bagnold profile is observed. The vibrations mainly cause the decrease of the basal friction and thus influence the height of the deposits. In the vibration-driven regime, however, flows are triggered by the vibrations themselves. It appears that they induce velocity fluctuations that create a granular temperature. That temperature allows the activation of the reorganizations at the grain scale. This suppresses the apparent yield responsible for the flow jamming, and thus enables their control through the shear rate

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-10-03T18:05:38Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese - Álvaro Furtado - Doutorado em Economia - 2015 .pdf: 7465178 bytes, checksum: 392ded6aa77b9a39c8feaabe6e515406 (MD5) / Made available in DSpace on 2016-10-03T18:05:38Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese - Álvaro Furtado - Doutorado em Economia - 2015 .pdf: 7465178 bytes, checksum: 392ded6aa77b9a39c8feaabe6e515406 (MD5) Previous issue date: 2015-11-19 / CAPES / Motivado pelo forte aumento dos preços dos imóveis das cidades brasileiras verificado durante os anos 2000 e a partir do caso específico da cidade do Recife, esta tese objetiva analisar a dinâmica de preço das residências na referida cidade entre 2000 e 2012. Tal proposta é levada a efeito a partir de duas investigações específicas. Primeira, o trabalho constrói um índice de preços para o valor das residências a partir não só de pareamento nas características de variáveis estruturais, como também, de forma inédita na literatura, nas variáveis de amenidades locais para o nível de cidade (no caso a Cidade do Recife). Essa construção é aplicada à subdivisão geográfica da cidade (as regiões políticas administrativas (RPAs)) algo, na verdade, inexistente. Segunda, no sentido de obter evidências a respeito dos determinantes da variação destes preços, o trabalho aplica uma decomposição, devido a Firpo et al. (2006, 2007, 2009 e 2011), que permite mensurar a contribuição de variáveis estruturais e de amenidades locais ao nível de quantil da distribuição dos preços, aplicação inédita no estudo do diferencial dos preços no mercado de imóveis. Para tal, são utilizados dados do ITBI e de shapefiles de amenidades do período de 2000 a 2012. Os resultados obtidos, quanto ao índice de preços, indicam que a dinâmica de preço dos imóveis varia de acordo com a RPA analisada, indicando que inferências sobre o mercado de imóveis com base em preços médios dos imóveis (ou medidas de tendência central) podem não refletir a realidade analisada. Já quanto à decomposição, constata-se que o efeito preço e o efeito dotação, resultantes da decomposição, tem dinâmicas diferentes na mesma variável apenas alterando-se o quantil. O comportamento aos extremos da distribuição (quantil 0,10 e 0,90) é fortemente influenciado pelas características dos imóveis, em especial as intrínsecas, já entre os quantis 0,20 e 0,80 o ambiente por si só é que é o protagonista do diferencial de preço e neste caso as características dos imóveis contribuem para que o diferencial de preço não seja ainda maior, com destaque para a variável área privada. Tais evidências revelam que o comportamento médio da cidade não pode ser generalizado ao nível de RPA e nem muito menos pode ser generalizado para todas as estratificações da distribuição de preço. / Motivated by the strong increase in property prices occurred in Brazilian cities during the 2000s and from the specific case of the city of Recife, this thesis aims to analyze the dynamics of house price in that city between 2000 and 2012. This proposal is carried out from two specific investigations. First, the work builds a price index for the value of dwellings from not only matching the characteristics of structural variables, but also in an unprecedented way in the literature, the variables of local amenities for the city level (in this case the Recife City). This construction is applied to the official geographical subdivision of the city, the RPAs (the Administrative Policy Areas) something actually non-existent. Second, to obtain evidence about the determinants of variation of prices, this work applies a decomposition due to Firpo et al. (2006, 2007, 2009 and 2011), it allows to measure the contribution of structural variables and local amenities over distribution of prices for the level of quantile, it's a unprecedented application in the differential study of prices in the real estate market. To this end, we use the ITBI data from 2000 through 2012 and the shapefiles of amenities. The results obtained as to the price index, show that the dynamic of price of properties varies according to the analyzed RPA, indicating that inferences about the real estate market based on average prices of dwellings (or central tendency statistics) may not reflect the analyzed reality. In respect the results of the decomposition, it is found that the coefficient and endowment effects have different dynamics in the same variable only by changing the quantile. The behavior at the extremes of the price distribution (quantile 0.10 and 0.90) is strongly influenced by the characteristics of the property, especially the intrinsic characteristics. For the quantiles from 0.20 through 0.80 the environment it's who is the protagonist of the price differences. In this case the real estate features contribute to the price differential do not be high, especially the private area variable. Such evidences show that the average behavior of the city may not be generalized to the level of RPA and much less may be generalized to all stratifications of the price distribution.

L’incorporation de particules inorganiques dans une matrice polymère confère de nouvelles propriétés au matériau ou améliore de manière significative les propriétés déjà existantes. Cependant, l’apparence visuelle perçue, telle que la transparence, peut être altérée par des phénomènes de diffusion de la lumière par les particules. Cette diffusion de la lumière est principalement conditionnée par la dimension des particules –ou agrégats de particules- et la différence d’indice de réfraction entre la matrice et les charges. Afin de traiter ces deux problèmes, l’objectif de nos travaux était de contrôler simultanément l’état de dispersion des nanoparticules inorganiques dans la matrice polymère et l’indice de réfraction des nanoparticules de façon à l’ajuster à celui de la matrice. Pour élaborer ce nouveau composite, nous avons synthétisé des nanoparticules hybrides cœur@écorce avec un cœur inorganique qui apporte les nouvelles propriétés et une écorce polymère d’épaisseur contrôlée, obtenue par polymérisation radicalaire contrôlée par voie nitroxyde amorcée à la surface des nanoparticules inorganiques. L’écorce polymère limite l’agrégation des particules et permet de modifier l’indice de réfraction moyen des nanoparticules cœur@écorce. En contrôlant l’épaisseur et la nature chimique de l’écorce polymère, nous cherchons à ajuster l’indice de réfraction des nanoparticules cœur@écorce à celui de la matrice. Les nanoparticules ont ensuite été dispersées dans une matrice de poly(méthacrylate de méthyle). Les propriétés optiques des composites ont été caractérisées par spectrogoniophotométrie, afin d’obtenir des informations sur l’intensité et la distribution angulaire de la lumière transmise par le composite. La transparence des nanocomposites a été fortement améliorée en ajustant l’indice de réfraction des nanoparticules cœur@écorce à celui de la matrice. / The incorporation of inorganic particles into a polymer matrix confers new properties to the material or enhances significantly existing properties. However, the perceived visual appearance, such as loss of transparency, might be modified by the scattering of light by the particles. This light scattering is mainly due to the particle –or aggregates of particles- dimensions and the refractive index difference between matrix and fillers. In order to address both issues, the objective of the present work was to control simultaneously the dispersion state of the inorganic nanoparticles into the polymeric matrix and the refractive index of the nanoparticles to match the one of the matrix. To achieve this new composite, we designed hybrid core@shell nanoparticles with an inorganic core that brings new properties and a polymer shell of controlled thickness, obtained by surface-initiated nitroxide mediated controlled radical polymerization. The polymer shell limits the aggregation of the particles and enables us to tune the average refractive index of the hybrid core@shell particle. By controlling the thickness and the chemical nature of the polymeric shell, we targeted to match the refractive index of the hybrid core@shell particle to the one of the polymeric matrix. The nanoparticles were further dispersed into a poly(methyl methacrylate) matrix. Optical properties of composites were characterized by spectrogoniophotometry which gave us informations about the intensity and the angular distribution of the transmitted light by the nanocomposites. The transparency of the nanocomposites was strongly enhanced for core@shell particles fulfilling the refractive index matching conditions.