A key problem in mobile computing is providing people access to necessary cyber-information associated with their surrounding physical objects. Mobile augmented reality is one of the emerging techniques that address this key problem by allowing users to see the cyber-information associated with real-world physical objects by overlaying that cyber-information on the physical objects's imagery. As a consequence, many mobile augmented reality approaches have been proposed to identify and visualize relevant cyber-information on users' mobile devices by intelligently interpreting users' positions and orientations in 3D and their associated surroundings. However, existing approaches for mobile augmented reality primarily rely on Radio Frequency (RF) based location tracking technologies (e.g., Global Positioning Systems or Wireless Local Area Networks), which typically do not provide sufficient precision in RF-denied areas or require additional hardware and custom mobile devices. To remove the dependency on external location tracking technologies, this dissertation presents a new vision-based context-aware approach for mobile augmented reality that allows users to query and access semantically-rich 3D cyber-information related to real-world physical objects and see it precisely overlaid on top of imagery of the associated physical objects. The approach does not require any RF-based location tracking modules, external hardware attachments on the mobile devices, and/or optical/fiducial markers for localizing a user's position. Rather, the user's 3D location and orientation are automatically and purely derived by comparing images from the user's mobile device to a 3D point cloud model generated from a set of pre-collected photographs. A further challenge of mobile augmented reality is creating 3D cyber-information and associating it with real-world physical objects, especially using the limited 2D user interfaces in standard mobile devices. To address this challenge, this research provides a new image-based 3D cyber-physical content authoring method designed specifically for the limited screen sizes and capabilities of commodity mobile devices. This new approach does not only provide a method for creating 3D cyber-information with standard mobile devices, but also provides an automatic association of user-driven cyber-information with real-world physical objects in 3D. Finally, a key challenge of scalability for mobile augmented reality is addressed in this dissertation. In general, mobile augmented reality is required to work regardless of users' location and environment, in terms of physical scale, such as size of objects, and in terms of cyber-information scale, such as total number of cyber-information entities associated with physical objects. However, many existing approaches for mobile augmented reality have mainly tested their approaches on limited real-world use-cases and have challenges in scaling their approaches. By designing fast direct 2D-to-3D matching algorithms for localization, as well as applying caching scheme, the proposed research consistently supports near real-time localization and information association regardless of users' location, size of physical objects, and number of cyber-physical information items. To realize all of these research objectives, five research methods are developed and validated: 1) Hybrid 4-Dimensional Augmented Reality (HD4AR), 2) Plane transformation based 3D cyber-physical content authoring from a single 2D image, 3) Cached k-d tree generation for fast direct 2D-to-3D matching, 4) double-stage matching algorithm with a single indexed k-d tree, and 5) K-means Clustering of 3D physical models with geo-information. After discussing each solution with technical details, the perceived benefits and limitations of the research are discussed with validation results. / Ph. D.

<p>More and more attention has been paid to decreasing the number and size of non-metallic inclusions existing in the final products recently in steel industries. Therefore, more efforts have been made to monitor the inclusions' size distributions during the metallurgy process, especially at the secondary steelmaking period. A liquid sampling procedure is one of the commonly applied methods that monitoring the inclusion size distribution in ladles, for example, during the secondary steelmaking. Here, a crucial point is that the steel sampler should be filled and solidified without changing the inclusion characteristics that exist at steel making temperatures. In order to preserve the original size and distributions in the extracted samples, it is important to avoid their collisions and coagulations inside samplers during filling. Therefore, one of the first steps to investigate is the flow pattern inside samplers during filling in order to obtain a more in-depth knowledge of the sampling process to make sure that the influence is minimized.</p><p>The main objective of this work is to fundamentally study the above mentioned sampler filling process. A production sampler employed in the industries has been scaled-up according to the similarity of Froude Number in the experimental study. A Particle Image Velocimetry (PIV) was used to capture the flow field and calculate the velocity vectors during the entire experiment. Also, a mathematical model has been developed to have an in-depth investigate of the flow pattern in side the sampler during its filling. Two different turbulence models were applied in the numerical study, the realizable k-ε model and Wilcox k-ω model. The predictions were compared to experimental results obtained by the PIV measurements. Furthermore, it was illustrated that there is a fairly good agreement between the measurements obtained by PIV and calculations predicted by the Wilcox k-ω model. Thus, it is concluded that the Wilcox k-ω model can be used in the future to predict the filling of steel samplers.</p>

As embarcações projetadas na atualidade possuem dimensões muito superiores às empregadas no passado recente do transporte marítimo, tanto para os navios de carga, quanto para os navios de cruzeiro. Esta realidade tem suas vantagens, permitindo o transporte de maior volume de cargas e passageiros, reduzindo os custos agregados às mercadorias e pessoas transportadas, mas, em contrapartida, traz desvantagens, pois essas embarcações possuem maior área exposta às ações ambientais, como ventos e correntes. Além disso, existe a demanda de amplos espaços náuticos, particularmente lâminas d\'água, e auxílio de rebocadores para acesso e atracação destas embarcações. Para reduzir os custos com as operações de dragagem, mais terminais portuários são construídos em áreas expostas a condições ambientais mais severas. Todas estas condições implicam diretamente no comportamento das embarcações atracadas, pois estas poderão estar sujeitas a movimentos de grande amplitude, suscetíveis de reduzir a eficiência e a segurança com que as operações de movimentação de carga são realizadas, podendo obrigar a sua interrupção e, nos casos mais críticos, provocar a ruptura das linhas de amarração e/ou danos nas defensas, podendo causar danos na estrutura de acostagem e na própria embarcação eventualmente, ocasionando vítimas. Levando em conta todos estes fatores, existem métodos pelos quais é possível o desenvolvimento de planos de amarração para conter os movimentos da embarcação durante a movimentação da carga e passageiros, buscando sempre obter o máximo de segurança nas operações no cais. Ainda para a verificação da eficácia e otimização dos planos de amarração, antes da sua implantação no terminal, existem métodos de análise, em que é possível estimar as forças exercidas nos cabos das linhas de amarração. Desta forma, este trabalho propôs-se a realizar uma pesquisa comparativa do emprego dos métodos analítico e de modelagem física. Assim, obteve-se uma avaliação crítica quanto à estimativa de esforços nos cabos das linhas de amarração de embarcações atracadas sob a ação de correntes. / Currently designed vessels have dimensions much higher than those used in the recent past of shipping, both for cargo ships and for cruise ships. This reality has its advantages, allowing the transportation of a larger volume of cargo and passengers, reducing the aggregate costs to the goods and people transported, but, on the other hand, it has disadvantages, since these vessels have greater area exposed to environmental actions, such as winds and currents. In addition, there is a demand for large nautical spaces, particularly water slides, and assistance of tugs for access and mooring of these vessels. To reduce costs with dredging operations, more port terminals are built in areas exposed to more severe environmental conditions. All these conditions directly imply the behavior of moored vessels, as these may be subject to large-scale movements, which may reduce the efficiency and safety with which the cargo handling operations are carried out, and may cause them to be interrupted and in the worst-case scenario,, damage the fenders and the berthing structure the vessel itself possibly causing casualties. Taking into account all these factors, there are methods by which it is possible to develop mooring plans to contain the movements of the vessel during the movement of the cargo and passengers, always seeking to obtain maximum safety on the dockside operations. In order to verify the efficacy and optimization of the mooring plans, prior to their implementation in the terminal, there are methods of analysis, in which it is possible to estimate the forces exerted on the ropes of the mooring lines. In this way, this work proposes to carry out a comparative research of the use of analytical and physical modeling methods. Thus, a critical evaluation was obtained regarding the estimation of efforts in the cables of the mooring lines of vessels moored under the action of currents.

Nesse trabalho, foi analisada a redução de arrasto, a partir da utilização de duas bancadas experimentais, onde uma delas está situada no laboratório de Mecânica dos Fluidos (EPUSP) e a outra, no laboratório de Fisiologia Vascular (ICB-USP). A redução de arrasto foi investigada a partir do uso dos seguintes polímeros: poliacrilamida 1822S e 1340S, polietileno glicol (PEG4000) e óxido de polietileno (Polyox WSR-301). O comportamento reológico das soluções poliméricas do PEG4000 e das poliacrilamidas foi adquirido experimentalmente, enquanto do Polyox WSR-301 foi obtido da literatura. Esses polímeros foram utilizados na bancada experimental da EPUSP, simulador hidrodinâmico, mas somente o PEG4000 foi utilizado na bancada experimental do ICBI em leitos arteriais caudais de ratos normotensos (Wistar) e espontaneamente hipertensos (SHR). No simulador hidrodinâmico, foi estudada a redução de arrasto em escoamentos pulsáteis laminares e turbulentos, cuja faixa de Reynolds varia entre 2300 a 13700, com concentrações poliméricas que variaram entre 5 e 100 ppm, porém para o PEG4000 essa concentração atingiu valor de 5000 ppm. Em leitos arteriais caudais de ratos, a redução de arrasto foi analisada para escoamento laminar, cuja faixa de Reynolds varia entre 100 e 700, com concentração polimérica de 5000 ppm. Além disso, a redução de arrasto foi estudada na presença e ausência das células endoteliais. Simulações computacionais utilizando o método dos volumes finitos (Fluent) foram realizadas a partir dos dados obtidos da bancada experimental do ICB-I, para avaliar a distribuição da tensão de cisalhamento sobre a parede do vaso na presença e ausência das células endoteliais e do PEG4000, considerando a parede da artéria rígida. A partir dos dados obtidos da análise da viscosidade, ficou constatado que o PEG4000 com concentração de 5000 ppm e as poliacrilamidas 1822S e 1340S com concentrações de 5 e 10 ppm apresentaram comportamento de fluido Newtoniano. Para as poliacrilamidas, concentrações poliméricas acima de 10 ppm apresentaram comportamento de fluido não-Newtoniano. De acordo com a literatura, o Polyox WSR-301 apresentou comportamento de fluido Newtoniano para todas as concentrações poliméricas utilizadas nesse trabalho. O PEG4000 não apresentou o fenômeno da redução de arrasto em nenhuma concentração polimérica analisada, quando aplicado na bancada experimental da EPUSP. As poliacrilamidas e o Polyox WSR-301 apresentaram reduções de arrasto que foram dependentes do número de Reynolds e da concentração utilizada, muito embora o Polyox WSR-301 tenha se mostrado mais eficiente em promover esse fenômeno. Nos leitos arteriais caudais, o PEG4000 apresentou redução de arrasto para a concentração de 5000 ppm, que foi acentuada pela presença das células endoteliais. Os valores da tensão de cisalhamento foram maiores para o animal SHR quando comparados com o animal Wistar. Além disso, no animal Wistar, o endotélio controlou o aumento dessa tensão via produção de substâncias vasodilatadoras, mas apresentou disfunção no animal SHR. A partir dos resultados apresentados acima, podese concluir que o Polyox WSR-301 é mais eficiente para promover a redução de arrasto em tubos rígidos. Por outro lado, muito embora o PEG4000 não tenha apresentado efeito na bancada experimental da EPUSP, esse se mostrou um bom redutor de arrasto em leitos arteriais caudais, tendo sua ação intensificada pela presença das células endoteliais. / In this work, the drag reduction was analyzed in two benches located at Laboratory of Fluid Mechanics at Polytechnic School (EPUSP) and at Laboratory of Vascular Physiology at Institute of Biomedical Science (ICB-USP). The drag reduction was investigated for the following polymers: polyacrilamide 1822S and 1340S, polyethylene glycol (PEG4000) and polyethylene oxide (Polyox WSR-301). The rheological behavior of polymeric solutions of polyacrilamide and PEG4000 was acquired experimentally; while it was obtained from the literature for Polyox WSR-301. All of these polymers were used in the hydrodynamic simulator, but only PEG4000 was employed in the tails arterial bed from normotensive (Wistar) and spontaneously hypertensive rats (SHR) at ICB-1. In the hydrodynamic simulator, the drag reduction was analyzed in laminar and turbulent pulsatile flow, in the range varying between 2300 and 13700, with polymeric concentrations between 5 and 100 ppm, but for PEG4000, concentration has reached 5000 ppm. On the other hand, in the tail arterial beds, the drag reduction was analyzed for laminar flow, in the range between 100 and 700, with polymeric concentration of 5000 ppm. In addition, it was studied in the presence and absence of endothelial cells. Computational simulation using the finite volume method (Fluent) was performed using data obtained from ICB-1 in order to analyze the wall shear stress distribution along of wall vessel both in the presence and absence of endothelial cells and PEG4000, considering the rigid walls. Polyacrilamide 1822S and 1340S as well as PEG4000 showed behavior of Newtonian fluid in the following concentrations: 5 and 10 ppm and 5000 ppm, respectively. On the other hand, for polyacrilamides, concentrations higher than 10 ppm showed behaviour of non- Newtonian fluids. According to the literature, the Polyox WSR-301 behaved as a Newtonian fluid in all concentrations used in this work. At EPUSP\'s bench, while PEG4000 did not show drag reduction for any polymeric concentration analyzed, this phenomenon could be seen for polyacrilamides and Polyox WSR-301, being dependent on Reynolds number as well as polymeric concentration. More important, Polyox WSR- 301 showed to be the most efficient drag reducer of them. Interestingly, in the assays employing the tail arterial beds, PEG4000 showed drag reduction in the concentration of 5000 ppm and it was increased by the presence of the endothelial cells. Thus, Polyox WSR-301 seems to be more efficient to promote drag reduction in the rigid tubes. On the other hand, while PEG4000 did not show drag reduction at EPUSP\'s bench, it was a good drag reducer in the tail arterial beds, being intensified by the action of endothelial cells.

This thesis focuses on the application of model predictive control approaches to optimize the combined cycle power plants start-ups. Generally, the optimization of start-up is a very problematic issue that poses significant challenges. The development of the proposed approaches is progressive. In the first part a physical model of plant is developed and adapted to optimization purposes, by using a methodology which transforms Modelica model components into optimization-oriented models. By applying this methodology, a library suitable for optimization purposes has been built.In the second part, based on the developed model, an optimization procedure to improve the performances of the start-up phases is suggested. The proposed solution optimizes, in continuous time, the load profile of the turbines, by seeking in specific sets of functions. The optimal profile is derived by considering that this profile can be described by a parameterized function whose parameters are computed by solving a constrained optimal control problem. In the last part, the open-loop optimization procedure has been integrated into a receding horizon control strategy. This strategy represents a robust solution against perturbation and models errors, and enables to improve the trade-off between computation time and optimality of the solution. Nevertheless, the control approach leads to a significant computation time. In order to obtain real-time implementable results, a hierarchical model predictive control structure with two layers, working at different time scales and over different prediction horizons, has been proposed.

La notion d'instrumentalité peut être définie comme la relation corporelle entre un humain et un objet physique, dit instrument. Ce corps à corps intime, qui adresse simultanément les différents canaux sensoriels d'action et de perceptions humaines, constitue un vecteur pour la connaissance enactive. Cette relation instrumentale joue notamment un rôle clé pour la richesse expressive des instruments musicaux.Dans le contexte informatique, un vaste champ de recherche concerne l'interaction sensorielle avec des entités virtuelles par le biais de capteurs et d'actionneurs, notamment l'interaction gestuelle avec les systèmes à retour d'effort. D'une part, les Réalités Virtuelles, historiquement centrées sur la visualisation, focalisent essentiellement l'interaction gestuelle sur des propriétés spatiales, souvent au détriment de qualités dynamiques. D'autre part, les Instruments Musicaux Numériques sont essentiellement centrés sur le contrôle interactif de processus de synthèse sonore numériques, basés sur le traitement de l'information. Ces deux scénarii synthétisent des phénomènes sensoriels destinés à différents canaux perceptifs selon une approche multimodale, l'objet virtuel étant décomposé en sous-parties, liées entre elles par des relations de contrôle.Il est néanmoins possible de concevoir des systèmes permettant l'interaction instrumentale avec un objet virtuel simulé, avec une cohérence énergétique bidirectionnelle totale, du geste au son et réciproquement. Il est alors nécessaire de regrouper (a) un formalisme de modélisation physique permettant la création d'objets virtuels intrinsèquement multisensoriels, possédant à la fois des propriétés visuelles, acoustiques et haptiques, (b) des systèmes à retour d'effort de grande performance dynamique et (c) des architectures de calcul spécialisées, permettant une boucle de simulation synchrone réactive à haute vitesse.Le travail de cette thèse consiste en l'extension et la convergence des concepts et techniques ci-dessus pour la mise en œuvre d'une plateforme de création musicale instrumentale, dite MSCI (modeleur-simulateur pour la création instrumentale), en proposant une répartition multifréquence du calcul de simulation des instruments virtuels sur une nouvelle architecture matérielle synchrone. Un environnement de modélisation permet de concevoir intégralement l'instrument virtuel sur des principes mécaniques et physiques et de configurer le couplage physique entre celui-ci et l'utilisateur du monde réel lors de la simulation à retour d'effort.Il adresse entre autre la question de la répartition de la chaine instrumentale en zones à caractère majoritairement non-vibrant, dont la dynamique est de l'ordre du geste sensori-moteur humain, et en zones vibrantes, productrices du son. Ces deux parties de l'instrument peuvent être simulées à des fréquences différentes, adaptées aux phénomènes physiques dont elles sont le siège. Dans le cadre d'un formalisme de simulation physique garantissant la cohérence énergétique des objets simulés, la séparation multifréquence est une problématique nouvelle qui nécessite d'être abordée avec précaution, pour des questions de respect du couplage physique ainsi que de stabilité numérique.Il s'agit, à notre connaissance, du premier environnement de création musicale par modélisation physique modulaire permettant la manipulation instrumentale d'instruments virtuels multisensoriels, respectant une cohérence énergétique entre homme et instrument, et permettant de jouir du potentiel créatif de la synthèse sonore tout en retrouvant l'intimité et la richesse de l'interaction gestuelle instrumentale. Au delà du cadre musical, ce travail pose les bases et les outils technologiques pour un véritable art multisensoriel, adressant conjointement la vision, l'oreille ainsi que le geste humain. / The notion of instrumentality can be defined as the corporal relationship between a human and a physical object, called an instrument. This intimate situation simultaneously addresses the various human action and perception sensory canals, and constitutes a vector for enactive knowledge. In particular, this instrumental relationship plays a key role in the expressiveness of musical instruments.In the digital context, a vast area of research concerns sensory interactions with virtual entities, by means of sensors and actuators, including gestural interaction with force feedback systems. On the one hand the Virtual Reality domain, historically focused on visual aspects, generally focus gestural interaction on spatial features, often losing the focus of dynamic features. On the other hand, Digital Musical Instruments are essentially centered on interactive control of digital sound synthesis processes, grounded in information technologies and signal processing. These two approaches synthesize sensory phenomena destined to different perceptive channels following a multimodal approach, the virtual object being decomposed into subsections, linked together by control relations.It is however possible to conceive systems that allow for instrumental interaction with a virtual simulated object, maintaining total and bidirectional energetic coherence, from gesture to sound and reciprocally. In this case, it is necessary to bring together (a) a physical modeling formalism that allows creating intrinsically multisensory virtual objects that possess visual, acoustical and haptic properties, (b) force feedback systems with high dynamic performances and (c) specialized computation architectures that allow for a reactive, high rate synchronous simulation loop.The work of this thesis consists in the extension and convergence of concepts and techniques hereby mentioned here-above, in order to create a platform for instrumental musical creation, named MSCI (Modeleur Simulateur pour la Création Instrumentale), proposing a multi-rate architecture for the simulation of virtual musical instruments on a new dedicated simulation architecture. A modeling environment allows complete design of the virtual instrument based on mechanical and physical principles, and to configure the haptic coupling between this instrument and the user during the force-feedback simulation.Notably, it addresses the separation of the instrumental chain into zones which present mostly non-vibrating phenomena within a dynamic range close to the human sensory-motor gesture, and zones which vibrate at acoustical rates, producing sound. These two sections of the instrument may be simulated at different rates, adapted to the physical phenomena that they give birth to. In the scope of a physical modeling formalism that guarantees the energetic coherence of simulated objects, this multi-rate separation is a new topic that requires careful handling, in terms both or respect of the physical coupling and of numerical stability.To our knowledge, this is the first environment for musical creation by means of physical modeling that allows for instrumental manipulation of multisensory virtual instruments, respecting an energetic coherence between the human and the instrument, and therefore allowing embracing the creative potential of digital sound synthesis while disposing of the intimacy and expressiveness of instrumental gestures. Beyond the musical scope, this work provides the basis and the technological tools for the emergence of a true multisensory form of art, jointly addressing vision, hearing and gesture.

Les travaux décrits dans ce document abordent le problème du couplage dynamique homme-système haptique. Nous proposons une étude de ce couplage basée sur l'hypothèse d'un système hybride temporaire. Selon cette hypothèse, le système formé lors du couplage peut être considéré comme un système dynamique dont les deux parties ne peuvent pas être séparées. Ce sujet est pluridisciplinaire, se situant à l'intersection des sciences cognitives, de l'automatique et de l'haptique. La première partie du document comporte un état de l'art sur l'analyse du couplage dans ces trois domaines, une description de la problématique et de la méthode à utiliser pour notre étude ainsi qu'une proposition des typologies du geste. Lors de cette étude du couplage, nous nous intéressons à un groupe de gestes particuliers, notamment le geste périodique et le geste passif dans une situation de simulation haptique ainsi qu'aux modèles d'interaction capables de les générer. La méthode générale, consiste à définir des approches pour la modélisation du couplage main-système haptique pour ensuite réaliser une analyse du système couplé à partir d'une acquisition des données du système lors du couplage et en utilisant des méthodes d'identification de paramètres issus de l'automatique pour caractériser les modèles. La dernière partie, décrit la mise en place du dispositif pour l'analyse expérimentale du couplage en situation de simulation avec une interaction haptique. Ce dispositif permet l'acquisition des données du geste pour l'analyse. Nous présentons également, l'étude réalisée sur le simulateur haptique afin d'établir l'équivalence entre les paramètres virtuels introduits et issus du simulateur et des paramètres physiques réels. Ensuite, nous décrivons l'analyse expérimentale des différentes situations de couplage proposées. Les expériences effectuées lors de cette étude ont été réalisées sur la plateforme temps réel ERGON_X, conçue par l'ACROE/ICA. Les résultats de ces expériences ont permis de quantifier les modèles du geste et d'observer ses composantes, selon les modèles établis. Mots clés : haptique, interface haptique, interfaces homme-machine, simulation temps réel, couplage homme-objet, geste, modélisation physique, identification de paramètres. / The work described in this document deals with the problem of human-haptic system dynamic coupling. We propose a study of this kind of coupling based on the hypothesis of a temporary hybrid system. Under this hypothesis, the system formed during the coupling can be considered as a dynamic system in which the two parties that compose it cannot be separated. This is multidisciplinary topic, situated at the intersection of cognitive science, automation and haptics. The first part of the document includes a state of the art on the analysis of coupling in these three areas, the description of the problem and the methodology for the study as well as a proposal of gesture typology. In this study of coupling, we are interested in a particular group of actions, such as periodic movement and passive gesture in a situation of haptic simulation and also, in the interaction models able to generate them. The general method is to define the approaches for modeling the hand-haptic device coupling and then perform an analysis of the coupled system by acquiring system data during the coupling and using parameter identification methods to characterize the models. The final section describes the implementation of the device for the experimental analysis of coupling during simulation with a haptic interaction. This device allows data acquisition for gesture analysis. We also present the study of the haptic simulator to establish the equivalence between virtual parameters introduced to and returned by the simulator and real physical parameters. Then, we describe the experimental analysis of different proposed coupling situations. The experiments performed for this study were performed using the real-time platform ERGON_X, designed by ACROE / ICA. The results of these experiments were used to quantify gesture models and to observe its components, according to established models. Keywords: haptic, haptic interface, human-machine interfaces, real-time simulation, human-object coupling, gesture, physical modeling, parameter identification.

Nesse trabalho, foi analisada a redução de arrasto, a partir da utilização de duas bancadas experimentais, onde uma delas está situada no laboratório de Mecânica dos Fluidos (EPUSP) e a outra, no laboratório de Fisiologia Vascular (ICB-USP). A redução de arrasto foi investigada a partir do uso dos seguintes polímeros: poliacrilamida 1822S e 1340S, polietileno glicol (PEG4000) e óxido de polietileno (Polyox WSR-301). O comportamento reológico das soluções poliméricas do PEG4000 e das poliacrilamidas foi adquirido experimentalmente, enquanto do Polyox WSR-301 foi obtido da literatura. Esses polímeros foram utilizados na bancada experimental da EPUSP, simulador hidrodinâmico, mas somente o PEG4000 foi utilizado na bancada experimental do ICBI em leitos arteriais caudais de ratos normotensos (Wistar) e espontaneamente hipertensos (SHR). No simulador hidrodinâmico, foi estudada a redução de arrasto em escoamentos pulsáteis laminares e turbulentos, cuja faixa de Reynolds varia entre 2300 a 13700, com concentrações poliméricas que variaram entre 5 e 100 ppm, porém para o PEG4000 essa concentração atingiu valor de 5000 ppm. Em leitos arteriais caudais de ratos, a redução de arrasto foi analisada para escoamento laminar, cuja faixa de Reynolds varia entre 100 e 700, com concentração polimérica de 5000 ppm. Além disso, a redução de arrasto foi estudada na presença e ausência das células endoteliais. Simulações computacionais utilizando o método dos volumes finitos (Fluent) foram realizadas a partir dos dados obtidos da bancada experimental do ICB-I, para avaliar a distribuição da tensão de cisalhamento sobre a parede do vaso na presença e ausência das células endoteliais e do PEG4000, considerando a parede da artéria rígida. A partir dos dados obtidos da análise da viscosidade, ficou constatado que o PEG4000 com concentração de 5000 ppm e as poliacrilamidas 1822S e 1340S com concentrações de 5 e 10 ppm apresentaram comportamento de fluido Newtoniano. Para as poliacrilamidas, concentrações poliméricas acima de 10 ppm apresentaram comportamento de fluido não-Newtoniano. De acordo com a literatura, o Polyox WSR-301 apresentou comportamento de fluido Newtoniano para todas as concentrações poliméricas utilizadas nesse trabalho. O PEG4000 não apresentou o fenômeno da redução de arrasto em nenhuma concentração polimérica analisada, quando aplicado na bancada experimental da EPUSP. As poliacrilamidas e o Polyox WSR-301 apresentaram reduções de arrasto que foram dependentes do número de Reynolds e da concentração utilizada, muito embora o Polyox WSR-301 tenha se mostrado mais eficiente em promover esse fenômeno. Nos leitos arteriais caudais, o PEG4000 apresentou redução de arrasto para a concentração de 5000 ppm, que foi acentuada pela presença das células endoteliais. Os valores da tensão de cisalhamento foram maiores para o animal SHR quando comparados com o animal Wistar. Além disso, no animal Wistar, o endotélio controlou o aumento dessa tensão via produção de substâncias vasodilatadoras, mas apresentou disfunção no animal SHR. A partir dos resultados apresentados acima, podese concluir que o Polyox WSR-301 é mais eficiente para promover a redução de arrasto em tubos rígidos. Por outro lado, muito embora o PEG4000 não tenha apresentado efeito na bancada experimental da EPUSP, esse se mostrou um bom redutor de arrasto em leitos arteriais caudais, tendo sua ação intensificada pela presença das células endoteliais. / In this work, the drag reduction was analyzed in two benches located at Laboratory of Fluid Mechanics at Polytechnic School (EPUSP) and at Laboratory of Vascular Physiology at Institute of Biomedical Science (ICB-USP). The drag reduction was investigated for the following polymers: polyacrilamide 1822S and 1340S, polyethylene glycol (PEG4000) and polyethylene oxide (Polyox WSR-301). The rheological behavior of polymeric solutions of polyacrilamide and PEG4000 was acquired experimentally; while it was obtained from the literature for Polyox WSR-301. All of these polymers were used in the hydrodynamic simulator, but only PEG4000 was employed in the tails arterial bed from normotensive (Wistar) and spontaneously hypertensive rats (SHR) at ICB-1. In the hydrodynamic simulator, the drag reduction was analyzed in laminar and turbulent pulsatile flow, in the range varying between 2300 and 13700, with polymeric concentrations between 5 and 100 ppm, but for PEG4000, concentration has reached 5000 ppm. On the other hand, in the tail arterial beds, the drag reduction was analyzed for laminar flow, in the range between 100 and 700, with polymeric concentration of 5000 ppm. In addition, it was studied in the presence and absence of endothelial cells. Computational simulation using the finite volume method (Fluent) was performed using data obtained from ICB-1 in order to analyze the wall shear stress distribution along of wall vessel both in the presence and absence of endothelial cells and PEG4000, considering the rigid walls. Polyacrilamide 1822S and 1340S as well as PEG4000 showed behavior of Newtonian fluid in the following concentrations: 5 and 10 ppm and 5000 ppm, respectively. On the other hand, for polyacrilamides, concentrations higher than 10 ppm showed behaviour of non- Newtonian fluids. According to the literature, the Polyox WSR-301 behaved as a Newtonian fluid in all concentrations used in this work. At EPUSP\'s bench, while PEG4000 did not show drag reduction for any polymeric concentration analyzed, this phenomenon could be seen for polyacrilamides and Polyox WSR-301, being dependent on Reynolds number as well as polymeric concentration. More important, Polyox WSR- 301 showed to be the most efficient drag reducer of them. Interestingly, in the assays employing the tail arterial beds, PEG4000 showed drag reduction in the concentration of 5000 ppm and it was increased by the presence of the endothelial cells. Thus, Polyox WSR-301 seems to be more efficient to promote drag reduction in the rigid tubes. On the other hand, while PEG4000 did not show drag reduction at EPUSP\'s bench, it was a good drag reducer in the tail arterial beds, being intensified by the action of endothelial cells.

Les cellules eukaryotes sont compartimentées par des structures intracellulaires nommées organites. On peut citer le réticulum endoplasmique, l'appareil de Golgi, le réseau endosomal et lyzosomal. Ces structures délimitées par des membranes cellulaires sont hautement dynamiques, structures dont les composants s'échangent sans cesse entre les différents compartiments. Malgré cette dynamique, les structures qui composent les réseaux d'organites sont très stables et robustes, de sorte que l'on peut décrire un état stationnaire pour ces systèmes hors équilibre et auto-organisés. Bien qu'ils soient robustes en conditions physiologiques, ces compartiments peuvent subir des modification de structures en condition pathologiques ou sous l'effet de traitements pharmacologiques. L'auto-organisation de systèmes à l'équilibre et relativement bien compris par le biais de diagrammes de phases, où l'on peut représenter lesdites phases en fonctions de paramètres physiques, tels que la concentration, ou les interaction entre les différents composants. La situation est bien moins prédictible pour des systèmes hors équilibre. C'est là donc une question scientifique intéressante que de comprendre les mécanismes contraignant l'organisation intracellulaire, où transports actifs et modification biochimiques des composant, tout deux consommant de l'énergie, sont en compétition avec des phénomènes passifs telle que la diffusion. Nous étudions, aussi bien numériquement qu'analytiquement, des modèles d'auto-organisation et de transport, dans des systèmes où un nombre réduit de composants s'organisent par le biais de réaction stochastiques, en des structures de grandes tailles. La question principale que nous posons est de comprendre comment les dynamiques d'échanges entre compartiments (par le biais de vésiculations et de fusion) jouent de concert avec les cinétiques de maturation des composants d'organites, permettent la mise en place d'un réseau robuste. A cette fin, nous nous focalisons sur un organite type, multi-compartiments, doté d'une dynamique riche de transport et de maturation de ses composants : l'appareil de Golgi. Nous décrivons et analysons l'état stationnaire de ces systèmes, en des termes de tailles et de pureté des compartiments le composant - sont ils gros ou petit, triés dans leur composition ou mixés. De cet état stationnaire émerge spontanément un transport de vésicules entre les compartiments, dont la directionnalité est intimement liée à l'état stationnaire. Ce transport est antérograde dans les régimes triés, rétrograde dans les régimes mixés. Des interactions locales, entre les compartiments et ce qu'ils renferment (protéines dont le nom générique est cargo), suffisent à biaiser ces dynamiques de transport. Cela impacte à la fois le temps de résidence des cargos, mais aussi leur localisation dans le système. La capacité de cet organite à trier ces cargos dépend cependant grandement de l'état stationnaire précédemment décrit. / Eukaryotic cells are highly compartmentalized into intracellular organelles, such as the endoplasmic reticulum, the Golgi apparatus, endosomes and lysosomes. These are dynamical structures bounded by lipid membranes, within which components undergo biochemical modification by enzymes, and between which components are constantly being exchanged. Despite their highly dynamical nature, their spatial organization is fairly well conserved over time, so that they could be seen as stationary states of a highly non-equilibrium, and multi-component system. On the other hand, this organization has been observed to be totally disorganized in pathologies or drug treatments. Self-organization in equilibrium systems is fairly well understood by means of phase diagrams where the occurrence of different phases (dispersed, condensed, phase separated) depends on physical parameters (concentrations, interaction energy between components). The situation is much less clear for non-equilibrium systems. It is therefore an exciting challenge to reach a quantitative understanding of the mechanisms dictating the intra-cellular organization, where active transport and biochemical modification by energy-consuming enzymes compete with purely passive phenomena such as diffusion. We design and study, both analytically and numerically, simple models of self-organization and transport in systems where a limited number of components may self-organize into larger structures by means of stochastic reactions. Our main fundamental question is to determine how the interplay between the dynamics of inter-organelle exchange (by means of vesicle secretion, transport and fusion) and the kinetics of biochemical maturation within organelles may yield a precise and robust organelle network. To this end we focus on one "stereotype" organelle, that is already multi-compartments and with a very rich dynamics of vesiculation, fusion and maturation: the Golgi Apparatus. We describe and understand the steady-state organization of such systems, in term of compartments' size and purity - how big and well sorted are the different compartments. From this steady-state, a vesicular transport spontaneously emerges, whose directionality is linked to the steady-state organization. It is anterograde in a pure regime, and retrograde in a mixed configuration. Local interaction between components being transported, and membranes are sufficient to bias those transport. This both change the kinetics of transport in the system, and thus their location in the compartments. How efficient the system is in sorting these elements, strongly relies on the steady-state organization and the vesicular transport.

Les environnements côtiers se caractérisent en de très nombreux endroits, depuis les zones tropicales jusqu’à des latitudes tempérées à froides, par des sédiments qui sont constitués d’un mélange de particules silicoclastiques et bioclastiques. Les processus de transport qui s’opèrent dans ces environnements dits "mixtes" sont difficiles à quantifier et modéliser compte tenu des différences de comportement hydrodynamique entre les particules silicoclastiques,souvent de forme sub-sphérique, et les particules bioclastiques dont les formes sont beaucoup plus complexes. En lien avec cette problématique, l’objectif général de la thèse est d’évaluer si des modifications de la composition de sédiments mixtes peut avoir un impact significatif sur la dynamique du trait de côte, et plus spécifiquement sur les modalités de construction des barrières littorales. Pour répondre à cet objectif une approche expérimentale a été choisie. Des expérimentations en érodimètre sous courant unidirectionnel mettent en évidence le comportement singulier des débris bioclastiques par rapport à des particules silicoclastiques, et surtout des différences significatives de comportement entre des bioclastes provenant de diverses espèces de mollusques. Ces résultats pourraient permettre notamment d’améliorer les modèles numériques de transport sédimentaire. Des expérimentations dans un grand canal à houle montrent clairement que des barrières littorales reconstituées à partir de mélanges en proportions variables de sédiments silicoclastiques et bioclastiques ont des caractéristiques morphologiques et des architectures internes différentes. Les barrières très bioclastiques sont plus hautes et moins larges que les barrières contenant plus de particules silicoclastiques. Ces conclusions suggèrent qu’une augmentation en apports bioclastiques pourrait avoir un effetpositif sur la stabilité des barrières littorales. / In many areas, coastal environments, from tropical to temperate-cold zones, are characterizedby mixed sediments, i.e. made of a mixture of siliciclastic and biogenic particles. Processes oftransport that occur in these so-called "mixed" environments are difficult to quantify and modeldue to the differences in hydrodynamic behaviour between siliciclastic particles, generally ofsub-spherical shape, and bioclastic particles the shape of which is very complex. The presentPhD work is related to this topic and aims in evaluating if changes in the composition ofmixed sediments can impact significantly the dynamics of the coastline, and more specificallythe construction modes of coastal barriers. To reach this objective an experimental approachhas been developed. Experiments in unidirectional current flume (erodimeter) highlight thesingular behaviour of bioclastic debris in comparison with that of siliciclastic particles, as wellas significant differences in behavior between bioclasts from various mollusc species. Theseresults could help in improving numerical models of natural sediment transport. Experimentsin a large wave flume clearly show that coastal barriers reconstructed from mixtures of varyingproportions of siliciclastic and bioclastic sediments have different morphological characteristicsand internal architectures. Barriers with high content in bioclastic debris are thicker andnarrower compared to barriers containing more siliciclastic particles. These findings suggestthat an increase in bioclastic inputs may have a positive effect on the stability of littoral barriers.