Дисертації з теми "Flexible suspension"

La dynamique de filaments flexibles individuels en écoulement visqueux est une étape essentielle pour comprendre et contrôler la rhéologie de nombreux fluides complexes. Cette dynamique sous-tend également une multitude de processus biophysiques allant de la propulsion des micro-organismes aux écoulements intracellulaires. Cette thèse présente des expériences systématiques permettant d’étudier la dynamique de filaments flexibles browniens dans un écoulement visqueux. Nous avons choisi d’utiliser un biopolymère, l’actine, comme système modèle de filaments. Sa longueur typique varie de 1 à 100 μm, il est flexible à ces échelles avec une longueur de persistance de l’ordre de 20μm, à cause de ses petites dimensions, il est soumis aux forces Browniennes avec des fluctuations en flexion, et enfin il peut être marqué en fluorescence. Nous utilisons des dispositifs microfluidiques associés à des systèmes de contrôle d’écoulements, un microscope optique équipé́ avec une platine motorisée pour réaliser des expériences contrôlées permettant de suivre la dynamique des filaments d’actine dans un écoulement de cisaillement pur et dans un écoulement élongationnel. Pour les expériences en cisaillement pur, des simulations reproduisant les conditions expérimentales ont aussi été́ menées en utilisant la théorie des poutres inextensibles d’Euler-Bernoulli et la théorie non locale des corps élancés en présence de fluctuations Browniennes et sont en accord quantitatif avec les résultats expérimentaux. Nous montrons que la dynamique des filaments dans ce système est principalement régie par le nombre élasto-visqueux, nombre sans dimension comparant les forces de trainée visqueuses aux forces de flexion élastiques, les fluctuations thermiques ne jouant qu’un rôle secondaire. Nous présentons une caractérisation complète des différents modes de déformation subies par le filament pendant une rotation ainsi que des transitions entre les différents modes. Dans la géométrie élongationnelle, nous avons choisi un canal hyperbolique optimisé pour permettre de longs temps de résidence sous taux de déformation constant. Nous avons observé́ directement la suppression des fluctuations transverse dans la partie extensionnelle tandis que nous observons, dans la partie compressive la formation de structures hélocoïdales tridimensionnelles après le flambage du filament. Pour finir, ce manuscrit de thèse décrit des développements expérimentaux permettant de fabriquer des suspensions de filaments d’actine relativement monodisperse en taille ainsi que des résultats préliminaires sur des effets rhéofluidifiants. Au bilan, les résultats présentes dans ce manuscrit pose les premières pierres de travaux futurs en direction de l’étude de la dynamique de ces filaments dans des écoulements plus complexes comme des écoulements de Poiseuille ou oscillants. Ils permettent aussi d’envisager des études sur le lien entre déformations de particules et propriétés des suspensions diluées d’objets flexibles et Brownien, lien encore peu étudié du point de vue expérimental
The dynamics of individual flexible filament in a viscous flow is the key to deciphering the rheolog- ical behavior of many complex fluids and soft materials. It also underlies a wealth of biophysical processes from flagellar propulsion to intracellular streaming. This thesis presents systematic exper- iments to investigate the dynamics of flexible and Brownian filaments in viscous flows. Biopolymer actin has been chosen to be our experimental model filament: its typical length can be varied from 1 to 100 μm, it is flexible at these dimensions with a persistence length in the order of 20μm, it is Brow- nian due to its small diameter with bending fluctuations and it can be labelled by fluorescent dye. Microfluidic channels and flow control systems are combined to optical microscope with automated stage to carry out well-controlled experiments on the diverse dynamics of actin filaments in shear flow and pure straining flow. In shear flow, simulations matching the experimental conditions have also been performed using inextensible Euler-Bernoulli beam theory and non-local slender body hy- drodynamics in the presence of thermal fluctuations and agree quantitatively with the experimental results. We demonstrate that filament dynamics in this flow geometry is primarily governed by a dimension- less elasto-viscous number comparing viscous forces to elastic forces with thermal fluctuations only playing a secondary role. We present a complete characterization of the different modes of defor- mation undergone by the filament while rotating as well as of the transitions between these different modes. In pure straining flow, we opt to use an optimized hyperbolic channel to allow long resi- dence time at constant strain rate to be applied. We directly observe the suppression of transverse fluctuations in the extensional part of the hyperbolic channel while we observe, in the compressive part of the flow, the formation of three dimensional helical structures subsequent to the initial buck- ling of the filament. Finally, this thesis manuscript also reports on experimental developments to fabricate suspensions of actin filament with a narrow distribution of lengths and on preliminary re- sults on shear-thinning effects. All together the results presented here pave the way of future studies towards the understanding of filament dynamics in more complex flows, as Poiseuille flows or oscil- latory flows, as well as towards establishing the link between filament deformations and rheological response in dilute suspensions of flexible Brownian filaments, which remains nearly unexplored from an experimental point of view

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000.
Includes bibliographical references (p. 365-372).
This thesis presents the design, analysis, and experimental testing of systems for noncontact suspension and control of flexible structures. Our particular focus is on the use of such suspensions in manufacturing processes which can be facilitated by the ability to control workpiece motion without contact. This can be of significant utility in processes such as coating, painting, heat treating, and web handling. We develop a novel approach for the control of such non-contact suspensions through what we term sensor averaging and actuator averaging. The difficult stability and robustness problems imposed by the flexible dynamics of the workpiece can be overcome by taking a properly-weighted average of the outputs of a distributed array of N motion sensors (sensor averaging), and/or by applying a properly-weighted distributed array of M forces (actuator averaging) to the workpiece. The theory for these dual techniques is developed in detail in the thesis. These approaches are shown to be independent of the specific boundary conditions or the longitudinal dimensions of the workpiece. These approaches are thus generally applicable to a wide range of structural control problems. We present both analytical and numerical analyses of the structural dynamics for typical flexible workpieces such as strings, beams, membranes, and plates. The analyses include axial translation of the workpiece. We have experimentally demonstrated the utility of our theory by application in the successful magnetic suspension of a 3 m long, 6.35 mm diameter, 0.89 mm wall thickness steel tube with varying boundary conditions. This is a very challenging problem due to the extremely light damping of the modes (< 0.001 with free ends). The experiment uses a set of 8 sensors and 8 actuators to measure and control the motion of the tube in the two lateral degrees of freedom. We present the details of the developed electromagnetic actuators, position sensors, modeling of the structural dynamics, the relevant vibration control techniques, and develop the associated theory for choosing sensor and actuator locations. Our results experimentally confirm the value of our averaging techniques, and suggest the wide future application of these ideas in industrial processes which require non-contact handling of workpieces.
by Ming-chih Weng.
Ph.D.

A new Direct Simulation fibre model was developed which allowed flexibility in the fibre during the simulation of fibre suspension flow.This new model was called the �Chain-of-Spheres �model.It was hypothesised that particle shape and deformation could signi ficantly a ffect partic e dynamics,and also suspension bulk properties such as viscosity.Data collected from the simulation showed that flexible fibres in shear flow resulted in an order of 7 −10% bulk relative viscosity increase over the �rigid �fibre result.Results also es- tablished the existence of a relationship between bulk viscosity and particle sti ffness.In comparison with experimental results,other more conventional rigid fibre based methods appeared to underpredict relative viscosity.The flexible fibre method thus markedly improved the ability to estimate relative viscosity.The curved rigid fibre suspension also exhibited increased viscosity of the order twice that of the equivalent straight rigid fibre suspension.With such sensitivity to fibre shape,this result has some important implications for the quality of fibre inclusions used.For consistent viscosity,the shape quality of the fibres was shown to be important. The �Chain of Spheres �simulation was substantially extended to create a new simulation method with the ability to model the dynamics of arbitrarily shaped particles in the Newtonian flow field.This new �3D Particle �simulation method accounted for the inertial force on the particles,and also allowed particles to be embedded in complex flow fields.This method was used to reproduce known dynamics for common particle shapes,and then to predict the unknown dynamics of various other particle shapes in shear flow. In later sections, the simulation demonstrated inertia-induced particle migration inthe non-linear shear gradient Couette cylinder flow,and was used to predict the fibre orientation within a diverging channel flow.The performance of the method was verified against known experimental measurements,observations and theoretical and numerical results where available.The comparisons revealed that the current method reproduced single particle dynamics with great fidelity. The broad aim of this research was to better understand the microstruc- tural dynamics within the fibre-filled suspension and from it,derive useful engineering information on the bulk flow of these fluids.This thesis represents a move forward to meet this broad aim.It is hoped that future researchers may bene fit from the new approaches and algorithms developed here.

Determination of the relation between the bulk or rheological properties of a particle suspension and its microscopic structure is an old and important problem in physical science. In general, the rheology of particle suspension is quite complex, and the problem becomes even more complicated if the suspending particle is deformable. Despite these difficulties, a large number of theoretical and experimental investigations have been devoted to the analysis and prediction of the rheological behavior of particle suspensions. However, among these studies there are very few investigations that focus on the role of particle deformability. A novel method for full coupling of the fluid-solid phases with sub-grid accuracy for the solid phase is developed. In this method, the flow is computed on a fixed regular 'lattice' using the lattice Boltzmann method (LBM), where each solid particle, or fiber, is mapped onto a Lagrangian frame moving continuously through the domain. The motion and orientation of the particle are obtained from Newtonian dynamics equations. The deformable particle is modeled by the lattice-spring model (LSM).The fiber deformation is calculated by an efficient flexible fiber model. The no-slip boundary condition at the fluid-solid interface is based on the external boundary force (EBF) method. This method is validated by comparing with known experimental and theoretical results. The fiber simulation results show that the rheological properties of flexible fiber suspension are highly dependent on the microstructural characteristics of the suspension. It is shown that fiber stiffness (bending ratio BR) has strong impact on the suspension rheology in the range BR < 3. The relative viscosity of the fiber suspension under shear increases significantly as BR decreases. Direct numerical simulation of flexible fiber suspension allows computation of the primary normal stress difference as a function of BR. These results show that the primary normal stress difference has a minimum value at BR ∼ 1. The primary normal stress differences for slightly deformable fibers reaches a minimum and increases significantly as BR decreases below 1. The results are explained based on the Batchelor's relation for non-Brownian suspensions. The influence of fiber stiffness on the fiber orientation distribution and orbit constant is the major contributor to the variation in rheological properties. A least-squares curve-fitting relation for the relative viscosity is obtained for flexible fiber suspension. This relation can be used to predict the relative viscosity of flexible fiber suspension based on the result of rigid fiber suspension. The unique capability of the LBM-EBF method for sub-grid resolution and multiscale analysis of particle suspension is applied to the challenging problem of platelet motion in blood flow. By computing the stress distribution over the platelet, the "blood damage index" is computed and compared with experiments in channels with various geometries [43]. In platelet simulation, the effect of 3D channel geometry on the platelet activation and aggregation is modeled by using LBM-EBF method. Comparison of our simulations with Fallon's experiments [43] shows a similar pattern, and shows that Dumont's BDI model [40] is more appropriate for blood damage investigation. It has been shown that channels with sharp transition geometry will have larger recirculation areas with high BDI values. By investigating the effect of hinge area geometry on BDI value, we intend to use this multiscale computational method to optimize the design of Bileaflet mechanical heart valves. Both fiber simulations and platelet simulations have shown that the novel LBM-EBF method is more efficient and stable compare to the conventional numerical methods. The new EBF method is a two-Cway coupling method with sub-grid accuracy which makes the platelet simulations possible. The LBM-EBF is the only method to date, to the best of author's knowledge, that can simulate suspensions with large number of deformable particles under complex flow conditions. It is hoped that future researchers may benefit from this new method and the algorithms developed here.

Šiuolaikinių tiltų įstabios architektūrinės formos ir tiltų statybos vietos ne visada leidžia pritaikyti dažniausiai naudojamas konstrukcines schemas. Todėl inžinieriams tenka pasinaudoti retesniais, mažiau tyrinėtais tiltų konstrukciniais variantais. Pastaruoju metu pasaulyje, ypač Kinijoje, vėl pradėta naudoti kabamųjų tiltų atmaina – neskėtrieji kabamieji tiltai. Išaugęs tokių tiltų poreikis reikalauja išsamios neskėtriojo kabamojo tilto elgsenos ypatumų analizės. Nuodugniam šios konstrukcinės schemos analizės atlikimui suformuluojamas darbo tikslas – išnagrinėti neskėtriųjų tiltų pradinės analizės metodus, įvairių variantų vienpilonių neskėtriųjų tiltų elgseną veikiant statinei apkrovai. Šiam tikslui pasiekti keliami tokie uždaviniai: 1. Apžvelgti kabamųjų tiltų konstrukcijas, jų projektavimo bei elgsenos ypatumus. 2. Išanalizuoti kabamųjų tiltų analizės metodus, išskiriant neskėtriųjų tiltų skaičiavimo ypatumus. 3. Išanalizuoti vienpilonių neskėtriųjų plieno tiltų elgseną, veikiant simetrinei ir asimetrinei apkrovoms. 4. Kabamojo tilto pradinei formai stabilizuoti pritaikyti baigtinio lenkiamojo standžio elementus. 5. Parinkti neskėtriojo tilto racionalius komponuojamuosius parametrus ir įvertinti neskėtriųjų kabamųjų tiltų panaudojimo galimybes. Darbe taikomas kompiuterinis modeliavimas baigtinių elementų metodu, naudojantis MIDAS Civil programa. Apžvelgiami gauti rezultatai ir pateikiamos išvados bei pasiūlymai.
Wonderful shapes of modern bridges, especially pedestrian, and their construction sites not always let to adapt usual bridge structure. That’s why engineers have to use unusual and less researched structures. Recently in the world, especially in China, other suspended structure is being used – self-anchored suspension bridges. Recently grown popularity of these bridges requires comprehensive self-anchored bridge behavioral analysis. For an extensive analysis accomplishment the objective is stated – to examine initial analysis methods of self-anchored suspension bridges, behavior of various two-span self-anchored bridges subjected to static loading. To achieve this objective, following tasks are raised: 1. Review suspension bridge structures, their analysis and design peculiarities. 2. Analyze calculation methods of suspension bridges, including peculiarities of self-anchored bridge design. 3. Analyze behavior of steel two-span self-anchored suspension bridge subjected to symmetrical and asymmetrical loading. 4. Apply finite bending stiffness elements for main cables to stabilize primer shape. 5. Evaluate self-anchored suspension bridge technical-economic performance. Computer-aided design using finite element program MIDAS Civil is applied in this research. An overview of the results with conclusions and recommendations are presented.

Робота складається із вступу та п’яти розділів. Загальний обсяг роботи: 150 аркушів основного тексту, 33 ілюстрацій, 31 таблиць, перелік посилань 41 найменувань та 5 додатків. Об’єкт дослідження – процес диспергування макулатурної маси у роторно-пульсаційному апараті. Предмет дослідження – кінетика процесу диспергування макулатурної маси у роторно-пульсаційному апараті. Мета дослідження – встановлення закономірностей диспергування макулатурної маси у роторно-пульсаційному апараті. Методи досліджень: теоретичний аналіз, математичне моделювання, експериментальне дослідження процесу диспергування в одноступінчастому роторно-пульсаційному апараті, встановленння функціональних залежностей, достовірності та адекватності розробленої математичної моделі. Результати роботи та їх новизна: - Сформульовано фізичну модель диспергування волокнистих суспензій у РПА. - Розроблено математичну модель кінетики пульсаційного диспергування волокнистих суспензій. - Експериментально перевірено адекватність фізичної та математичної моделі. − Складено алгоритм розрахунку РПА, з урахуванням особливостей процесу диспергування волокнистих суспензій. − Запропоновано варіант конструкції РПА, що дозволяє підвищити ефективність установки для проведення хіміко-технологічних процесів у рідинах, використавши прості, з точки зору виготовлення та встановлення, конструкційні елементи без зміни габаритних розмірів установки та ускладнення її обслуговування. − Розроблено технологічну схему з застосуванням РПА при виробництві макулатурної маси. Розроблено стартап проект, в якому проведеного аналіз перспективи впровадження з огляду на потенційні групи клієнтів, бар’єри входження, стан конкуренції, конкурентоспроможність проекту. Основний зміст дисертації викладено в 7-ми опублікованих роботах, у тому числі у двох статтях у наукових фахових виданнях України, чотирьох публікаціях в матеріалах міжнародних конференцій і наукових семінарів та в патенті України.
The work consists of an introduction and five sections. Total volume of work: 150 pages of the main text, 33 illustrations, 31 tables, list of references of 41 titles and 5 applications. The object of the study is the process of the waste paper dispersion in a rotary-pulsating apparatus. The subject of the study is the kinetics of the waste paper dispersion in a rotary-pulsating apparatus. The purpose of the study is to determine the regularities of the preparation of the waste paper dispersion in rotary-pulsating apparatus. Methods of research: theoretical analysis, mathematical modeling, experimental study of the dispersion process in a one-stage rotary-pulsating apparatus, the establishment of functional dependencies, and the reliability and adequacy of the developed mathematical model. Results of work and their novelty: − Physical model of dispersion of fibrous suspensions in RPA was formulated. − A mathematical model of the kinetics of pulsed dispersion fibrous suspensions has been developed. − The adequacy of the physical and mathematical model has been experimentally tested. − An algorithm for calculation of RPA, taking into account the features of the process of dispersing fibrous slurries, has been prepared. − A variant of the RPA design is proposed, which makes it possible to increase the efficiency of the installation for carrying out chemical and technological processes in liquids, using structural elements simple in terms of fabrication and installation, without changing the overall dimensions of the installation and complicating its maintenance. − The technological scheme that includes RPA in the production of waste paper has been developed. A startup project has been developed, in which the analysis of the implementation perspective takes into account the potential client groups, entry barriers, the state of competition, the competitiveness of the project. The main content of the dissertation is presented in 7 published works, including two articles in scientific professional editions of Ukraine, four publications in materials of international conferences and scientific seminars and in the patent of Ukraine.
Работа состоит из введения и пяти разделов. Общий объем работы 150 листов основного текста, 33 иллюстраций, 31 таблиц, список литературы 41 наименований и 5 приложений. Объект исследования - процесс диспергирования макулатурной массы в роторно-пульсационном аппарате. Предмет исследования - кинетика процесса диспергирования макулатурной массы в роторно-пульсационном аппарате. Цель исследования - установление закономерностей диспергирования макулатурной массы в роторно-пульсационном аппарате. Методы исследований: теоретический анализ, математическое моделирование, экспериментальное исследование процесса диспергирования в одноступенчатом роторно-пульсационном аппарате, уставновление функциональных зависимостей, достоверности и адекватности разработанной математической модели. Результаты работы и их новизна: − Сформулированы физическую модель диспергирования волокнистых суспензий в РПА. − Разработана математическая модель кинетики пульсационного диспергирования волокнистых суспензий. − Экспериментально проверено адекватность физической и математической модели. − Составлен алгоритм расчета РПА, с учетом особенностей процесса диспергирования волокнистых суспензий. − Предложен вариант конструкции РПА, что позволяет повысить эффективность установки для проведения химико-технологических процессов в жидкостях, использовав простые, с точки зрения изготовления и установки, конструкционные элементы без изменения габаритных размеров установки и усложнения ее обслуживания. − Разработана технологическая схема с применением РПА при производстве макулатурной массы. − Разработан стартап проект, в котором проведенного анализ перспективы внедрения учитывая потенциальные группы клиентов, барьеры вхождения, состояние конкуренции, конкурентоспособность проекта. Основное содержание диссертации изложены в 7-ми опубликованных работах, в том числе в двух статьях в научных изданиях Украины, четырех публикациях в материалах международных конференций и научных семинаров и в патенте Украины.

Cette thèse de doctorat contient trois résultats principaux. Dans le premier chapitre on construit un polyèdre infinitésimalement flexible dans l'espace hyperbolique à trois dimensions dont le volume n'est pas stationnaire sous sa flexion infinitésimale. Dans le deuxième chapitre on obtient une condition nécessaire de flexibilité des suspensions dans l'espace hyperbolique à trois dimensions. Dans les deux derniers chapitres on démontre l'existence d'une variété quasi-Fuchsienne convexe compacte dont la métrique induite de son bord est une métrique polyèdrale hyperbolique prescrite
This thesis contains three main results. In the first chapter we construct an infinitesimally flexible polyhedron in hyperbolic 3-space such that its volume is not stationary under the infinitesimal flex. In the second chapter we obtain a necessary condition for flexibility of suspensions in hyperbolic 3-space. In the last two chapters we show the existence of a quasi-Fuchsian convex compact manifold such that the induced metric on its boundary coincides with a prescribed hyperbolic polyhedral metric

This work investigated the design of classical and optimal control strategies to actively control the flexible modes of a high speed railway vehicle body. It explored the novel idea of adding a third actuator at the centre of the vehicle body to suppress the flexible body modes (i.e. first symmetrical and first asymmetrical) in addition to the actuators located across the front and rear secondary suspensions. The aim is to minimise the level of vibration and improve the ride quality (comfort). Both the two and three actuators are considered in the classical and optimal control strategies investigated.

Thesis (Ph.D.)--Mechanical Engineering, Georgia Institute of Technology, 2009.
Committee Co-Chair: Aidun, K. Cyrus; Committee Co-Chair: Ghiaasiaan, Mostafa; Committee Member: Deng, Yulin; Committee Member: Empie, Jeff; Committee Member: Patterson, Tim.

L'étude porte sur l'analyse et la prédiction du comportement dynamique des structures montées sur suspensions passives non linéaires. Dans un premier temps, une méthode expérimentale est développée pour identifier le comportement de suspension non linéaire de deux types de plots: un en élastomère et un à coussin métallique. Elle est mise en œuvre sur un banc d'essais spécifique. De nombreuses expérimentations ont mis en évidence la complexité du comportement des suspensions. Sachant que l'effet de la déflexion est prépondérant, un modèle théorique qui tient compte de la non-linéarité en raideur, est proposé. L'approche repose sur l'hypothèse de la superposition de déformations statique et dynamique non linéaires. Ensuite, pour prédire le comportement dynamique du système structure-suspension, un code de calcul élément finis et des algorithmes spécifiques ont été mis au point. Afin de rendre acceptable les temps de calcul, particulièrement dans le cas de réponse temporelle, il est indispensable de procéder à une réduction du nombre de degrés de liberté ( d. D. L. ). La méthode de Craigh et Bampton est bien adoptée à ce système: il est nécessaire de conserver les caractéristiques dynamiques de la structure et de disposer à tout instant les d. D. L. Relatifs aux suspension. La fiabilité du modèle de calcul a été éprouvée par des tests de validation analytiques et expérimentaux portant sur diverses structures rigides montées sur suspension non linéaire. Enfin, la prédiction du comportement de structures flexibles, s'est avérée très satisfaisante par rapport aux expérimentations réalisées sur des structures de type poutre montées sur suspension non linéaire et soumises à des chocs, ou des sollicitations harmoniques. Le travail développé permet la modélisation de structures industrielles, tels les supports d'équipements embarqués, et d'en prévoir le comportement
This research is concerned with the analysis and prediction of the dynamic behaviour of structures mounted on non-linear passive suspension. Experimental investigations using a specific experimental set-up have been performed as to identify the role of non linearities in the dynamic behaviour of visco-elastic mounts and of elasto-plastic mounts with dry friction. Experiments show the complex behaviour of the tested mounts and highlight the predominant effect of bath deflection and temperature. These effects are taken into account in the modelling of the mounts which involves the theory of the superposition of non-linear static and dynamic deflection. The specific Finite Element computer program permits the prediction of the dynamic behaviour of the structure/suspension assembly. The Craigh and Bampton method is well adapted to the problem: it permits an acceptable computation time of the time response. The reliability of the computation model has been analytically and experimentally tested on different kinds of rigid structure on non-linear mounts. The response of flexible structures including a beam clamped at one end and retained at the other end by a non-linear mount has been investigated under sine wave excitations and shocks. The experimental results show that the response of the structure is well predicted. The present study allows the modelling of industrial structures, such as shipping equipments, and the prediction of their non-linear behaviour

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Em um mundo globalizado, a demanda por energia está sempre crescendo. Uma vez que a indústria de óleo e gás é responsável pela entrega da maior parte desta demanda, isso faz dos hidrocarbonetos componentes cada vez mais importantes no mercado mundial. Entretanto tais recursos são finitos, portanto, uma exploração consciente, buscando sempre o máximo desempenho se faz necessária. Como os reservatórios de petróleo, logo após a aplicação das técnicas de recuperação primária e secundária, geralmente ainda possuem cerca de 65 por cento do volume de óleo originalmente contido em seus poros, métodos que visam a redução dessa porcentagem estão ganhando um papel cada vez mais importante na indústria energética. Nesse contexto, esse trabalho apresenta um micromodelo tridimensional representativo de um meio poroso que será utilizado para a análise do escoamento de fluidos na escala de poro. A microscopia confocal será adotada para visualizar os diferentes fenômenos que ocorrem em microescala, permitindo a obtenção de informações específicas sobre a dinâmica dos gânglios de óleo, em relação a sua formação, mobilização e aprisionamento, e assim, ao final do experimento quantificar a saturação residual de óleo em diferentes condições de escoamento. Os resultados obtidos mostram que o uso das suspensões de microcápsulas flexíveis como agente de controle de mobilidade, modifica a distribuição dos fluidos no meio poroso, o que melhora a eficiência de deslocamento do fluido deslocante na escala de poro, e consequentemente diminui a saturação de óleo residual.
In a globalized world, the demand for energy is always growing. Since the oil and gas industry is responsible for delivering most of this demand, this makes hydrocarbon components increasingly important in the worldwide economy. However, such resources are finite, so a conscious exploration always seeking the maximum performance is required. As oil reservoirs after the application of primary and secondary recovery techniques usually still have about 65 percent of the original oil volume contained in their pores, methods that aim its reduction are gaining an increasingly important role in the energy industry. In this context, this work presents a three-dimensional micromodel representative of a porous medium that is used for pore-scale flow analysis. Confocal microscopy is used to visualize the microscale phenomena, leading to specific information about ganglia dynamics, related to its formation, mobilization and entrapment. The residual oil saturation, an important value to measure the amount of oil produced in a given reservoir is determined for different flow conditions. The results show that the suspensions composed by flexible microcapsules could be used as a mobility control agent, since it modifies the fluid distribution in the porous media, improving the pore-scale displacement efficiency, and consequently reducing the residual oil saturation.

Les nanotubes de carbone mono-paroi (SWNT) sont souvent dilués dans un solvant afin de les purifier, les fonctionnaliser ou les transformer. Le contrôle de ces processus requiert une compréhension profonde de la rhéologie de leurs suspensions. Cependant, les bases physiques de leur comportement rhéologique ne sont pas absolument claires. Cette thèse a permis d'apporter des réponses au travers de la modélisation de la viscoélasticité linéaire des suspensions diluées de SWNTs en utilisant une approche par la Dynamique Brownienne (DB). Les SWNTs sont modélisés par des filaments semi-flexibles dont la configuration est naturellement courbée due à la présence de défauts structuraux. Le modèle continu de filament semi-flexible est discrétisé en un système multibarre en flexion non-libre ayant une configuration non-droite à l'équilibre. Une redéfinition du potentiel de flexion est effectuée afin de prendre en compte les cas des configurations non-rectilignes. Le comportement en viscoélasticité linéaire de leurs suspensions diluées a été modélisé par DB en mode dynamique et de relaxation. Des nouveaux processus de relaxation caractérisés par l'activation d'une élasticité à fréquences intermédiaires sont constatés en dynamique. D'autre part, une relaxation quasi-instantanée du module de relaxation est obtenue lors de l'application d'un échelon de cisaillement. Les spectres de relaxation de l'énergie de flexion sont en accord avec les réponses dynamiques, ce qui prouve la cohérence du modèle en viscoélasticité linéaire. Les différences non négligeables par rapport au comportement rhéologique des systèmes multibarre droits à l'équilibre démontrent que la flexibilité couplée avec la présence de défauts structuraux de courbure joue un rôle important dans la dynamique d'un SWNT en suspension.

碩士
國立高雄應用科技大學
土木工程與防災科技研究所
103
The aims of this study are to explore the feasibility of load test on Flexible Suspension Bridge. The method of this study is to use of structural analysis software SAP2000 to build numerical model. Firstly, it was to predict the impact of the load on the deck of suspension bridge under different load case in numerical model. Secondly, it was to implement load test on Suspension bridge in the field and to measure the elevation changes of the bridge deck at different load case of the bridge deck. Finally, this study compared the results of measurement in the field with the results of numerical simulation. Results of this study found that the measurement results of load test in the field were very close to the numerical simulation results of the bridge under different load case. The results of this study was Expected to provide a good reference of load test for the domestic suspension bridge.

碩士
國立臺灣大學
土木工程學研究所
100
Since 1998, Because of the revision of the Taiwan Vehicle Regulation, more than 5axle articulated vehicle that can formal load more goods ton under the legal situation. In conformity with the regulation change, someone cargo transporter starting re-build their current trailer, especially add a lift axle which behind of or in front of on current axle bogie. That can reduce tires wear when the axle lifted up for the trailer running with empty load situation. But Air Suspension system initial cost was most expensive than leaf spring suspension system, so most of Transporters only applied air suspension system on lift axle, other axles keep using original leaf spring suspension system. According to foreign countries study result of many years, if the single axle unit have same load state, using air suspension system will decrease 10~20% dynamic load on the road when it compare with leaf spring suspension system. For this reason, we will use Truck dynamic Simulate Software – TruckSim8.0 and Road Pavement surface value evaluation software- MEPDG 2002 that can study when the different Tractor types combined with different Trailer types in our local country, the trailer has assembly different type suspension system of the different axles, and running on a same road section that the International Roughness Index condition is limit on a 3.14m/km, which kind of assembly will cause reducing road surface life cycle. Following this result, we can try to definition Road-Friendliness Vehicle and Non Road-Friendliness Vehicle in our country.

No
A vehicle that deviates laterally from its intended path of travel when the brakes are applied is considered to demonstrate ‘instability’ in the form of an unexpected and undesirable response to the driver input. Even where the magnitude of lateral displacement of the vehicle is small (i.e. ‘drift’ rather than ‘pull’) such a condition would be considered unacceptable by manufacturers and customers. Steering ‘drift’ during braking can be caused by several factors, some of which relate to vehicle design and others to external influences such as road conditions. The study presented here examines the causes and effects of steering drift during straight-line braking. A comparative analysis is made between two types of vehicle model: one built with rigid suspension components and the other with flexible components. In both the cases, the vehicle behaviour is simulated during braking in a straight line, and responses including lateral acceleration, yaw rate, and lateral displacement of the vehicle are predicted and analysed under fixed steering control. Suspension/steering geometry characteristics, namely toe steer and caster angle, have been studied to understand how the effect of variations in these parameters differs in models with rigid or flexible components drift during straight-line braking. Results from both vehicle models show that differences between rigid and flexible components can affect the predicted steering drift propensity. The differences between the two models have emphasized the importance of using flexible (compliant) components in vehicle handling simulations to achieve better correlation between prediction and experiment.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1996.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 85-88).

碩士
國立清華大學
奈米工程與微系統研究所
99
We introduced a hybrid PDMS-silicon electrostatic actuator with a large stroke under low driving voltages. The device features a staggered vertical comb-drive suspended by PDMS springs. Because of the flexibility of PDMS, an initial staggered displacement was naturally formed due to the self-weight of the device. Experimental results showed the combination of polymeric springs and silicon structures enabled the large stroke of 3.73 μm at 3.5 kHz. The presented heterogeneous integration technology improves the performance and may bring new functionalities to micro-systems.