Made available in DSpace on 2014-12-17T14:56:07Z (GMT). No. of bitstreams: 1 DanielGVF_DISSERT.pdf: 2881772 bytes, checksum: 5236953fb6bb70560393eeeaa01f96f9 (MD5) Previous issue date: 2012-08-31 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The control, automation and optimization areas help to improve the processes used by industry. They contribute to a fast production line, improving the products quality and reducing the manufacturing costs. Didatic plants are good tools for research in these areas, providing a direct contact with some industrial equipaments. Given these capabilities, the main goal of this work is to model and control a didactic plant, which is a level and flow process control system with an industrial instrumentation. With a model it is possible to build a simulator for the plant that allows studies about its behaviour, without any of the real processes operational costs, like experiments with controllers. They can be tested several times before its application in a real process. Among the several types of controllers, it was used adaptive controllers, mainly the Direct Self-Tuning Regulators (DSTR) with Integral Action and the Gain Scheduling (GS). The DSTR was based on Pole-Placement design and use the Recursive Least Square to calculate the controller parameters. The characteristics of an adaptive system was very worth to guarantee a good performance when the controller was applied to the plant / As ?reas de controle, automa??o e otimiza??o contribuem para a melhoria dos processos utilizados pelas ind?strias, permitindo uma linha de produ??o r?pida, aprimorando a qualidade do produto final e reduzindo os custos de produ??o. Boas ferramentas para o desenvolvimento de pesquisas nestas ?reas s?o as plantas did?ticas, pois proporcionam um contato direto com equipamentos semelhantes ou at? mesmo usados no setor industrial. Em vista dessas capacidades, o objetivo deste trabalho ? modelar e controlar uma planta did?tica que consiste de um sistema de controle de processo para vaz?o e n?vel com instrumenta??o industrial. Com o modelo ? poss?vel construir um simulador capaz de permitir estudos a respeito do funcionamento do sistema, sem os gastos com a opera??o do processo real. ? o caso de experimentos com controladores, que podem ser testados diversas vezes antes de serem efetivamente utilizados no processo real. Dentre os diversos tipos de controladores existentes, foi dado foco aos de tipo adaptativo, principalmente ao auto-sintoniz?vel direto (Direct Self-Tuning Regulator DSTR) com a??o integral e ao controlador com Escalonamento de Ganho (Gain Scheduling GS). O controlador DSTR foi projetado com base no m?todo de posicionamento de p?los e teve seus par?metros calculados atrav?s da t?cnica dos m?nimos quadrados recursivos. As caracter?sticas dos sistemas adaptativos foram de grande valia para garantir um desempenho satisfat?rio dos controladores, quando aplicados ? planta

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Comprendre l’origine microscopique du ralentissement de la dynamique au voisinage de la transition vitreuse reste l’un des problèmes fondamentaux de la physique de la matière condensée. Au cours de ce travail, nous introduisons un nouveau modèle de liquide, appelé liquide de Voronoï, et dont les interactions sont directement reliées aux propriétés géométriques des tessellations de Voronoï. Pour cette classe de liquides, les interactions sont à plusieurs corps et agissent de telle sorte que le système est toujours sous tension tout en restant stable. Le but de ce travail est d’étudier un mélange binaire du liquide de Voronoï et de voir de quelles façons ces interactions exotiques affectent le scénario habituel de la transition vitreuse. Tout au long de ce travail, nous caractérisons le liquide de Voronoï bidisperse théoriquement et par le biais des simulations numériques. Nous proposons également des comparaisons avec des liquides de Lennard-Jones surfondus bien décrit dans la littérature. / Understanding the origin of the important slowing down of the dynamics near glass transition is still one of the remaining fundamental problems of condensed matter physics. During this work we introduced a brand-new model of liquids named Voronoi liquid, whose interactions are directly related to the geometrical properties of Voronoi tessellations. For these class of liquids interactions are intrinsically manybody and act in such a way that the liquid is always under tension but remains stable. The aim of this work is to use a binary mixture of the Voronoi liquid to see to what extend these exotic interactions may affect the classical scenario of glass transition. Throughout this work we characterize theoretically and by mean of numerical simulation the bidisperse Voronoi liquid. Comparisons with well-known Lennard-Jones glass formers are systematically performed.

La présente étude est une approche holistique axée sur l'étude des effets spécifiques d'ions sur les propriétés d'auto-assemblage de tensioactifs cationiques gemini. Notre objectif principal étant l’étude de l'effet de divers contre-ions sur les caractéristiques d’auto-assemblage de tensioactifs cationiques en solution aqueuse. Afin d'obtenir une vision plus complète de l'effet des interactions ioniques et moléculaires à l’interface sur les propriétés globales, nous avons utilisé des approches différentes. Nous avons combiné une étude expérimentale portant sur les propriétés en solution (concentration micellaire critique, degré d'ionisation, nombre d'agrégation, etc.), avec des approches centrées sur l'étude des propriétés micellaires interfaciales en analysant les concentrations des contre-ions et de l'eau de façon expérimentale (piégeage chimique) et informatique (simulations de dynamique moléculaire). En outre, nous avons étudié l'impact de la nature des contre-ions sur la croissance des micelles géantes par rhéologie. En plus de l'examen des propriétés de tensio-actifs en solution, les effets spécifiques d'ions sur les structures cristallines des agents tensioactifs gémini ont été étudiés.Nous avons trouvé que les effets d'ions spécifiques qui déterminent le comportement des agrégats micellaires de gemini cationiques d'ammonium quaternaire dans des solutions aqueuses dépendent fortement de l'énergie libre d'hydratation des contre-ions, en d'autres termes, sur leur propriétés hydrophile /hydrophobe. Contrairement à la solution aqueuse, dans les cristaux, la taille de l'ion devient le facteur déterminant. La comparaison des résultats obtenus pour un même système en solution aqueuse et à l'état solide a montré l'importance des interactions ion-eau dans les effets spécifiques d'ions. Cependant, il faut noter que les propriétés du substrat (les gemini dans notre cas) doivent être prises en compte non moins soigneusement afin de prédire complétement les effets Hofmeister. / The present study is a holistic approach focused on the investigation of ion specific effects on the self-assembly properties of cationic gemini surfactants. Our main focus was on the effect of various counterions on the self-organization features of cationic surfactants in aqueous solution. In order to obtain amore comprehensive understanding of the effect of interfacial ionic and molecular interactions on aggregate properties we used different approaches. We combined an experimental study focused on the bulk solution properties (critical micelle concentration, ionization degree, aggregation number, etc.), with approaches focused on investigating the interfacial micellar properties by analyzing the interfacial counterion and waterconcentrations, experimentally (chemical trapping) and computationally (molecular dynamic simulations). Moreover, the impact of counterion nature was investigated by studying the growth of wormlike micelles using rheology. Besides the examination of the surfactants properties in solution, the ion specific effects onthe crystalline structures of gemini surfactants were studied.We found that ion specific effects which determine the behavior of micellar aggregates of cationic quaternary ammonium gemini in aqueous solutions strongly depend on the free energy of hydration of the counterions, in others words, on their hydrophilic/hydrophobic properties. Contrarily to aqueous solution, in crystals, the size of the ion becomes the determining factor. Comparison of the results obtained for the same system in aqueous solution and in solid state showed the importance of ion-water interactions in ion specific effects. However, one should note that the properties of substrate (the gemini in our case) should be taken into account not less carefully in order to fully predict Hofmeister effects.

This dissertation thesis primarily focuses on the experimental measurement of energy consumption of a given energy-passive family house as well as theoretical research in the field of energy calculations using computer simulations. The results of quasi-stationary and dynamic simulations, with varying computational and real-time climate data, are compared with experimental measurements. Using the dynamic calculation model, which was validated by actually measured data, the relationship between architectural design and the energy performance of the building was analyzed. The influence of selected different operating modes for heat consumption on heating, cooling, ventilation, and interior overheating is observed. The result of the mutual interaction of several input parameters of variant solutions provides the basis for optimization of the whole design.

In this thesis, we start with the description of the biophysical properties of the plasma membrane models upon signaling processess such as the increased cytoso- lic concentration of calcium ions, or posttranslational modifications of membrane proteins. Calcium signaling is characterized by a rapid increase of its cytosolic concentration. We identify calcium binding sites and characterize the binding in the plasma membrane models of increasing complexity from pure phospholipid bilayers, through cholesterol and peptide rich lipid membranes, to membranes ex- tracted from HEK293 cells. We use Time-Dependent Fluorescent Shift method, which provides direct information on hydration and mobility in defined regions of a lipid bilayer, accompanied with molecular dynamic (MD) simulations, which give molecular details of the studied interactions. The initial step of signaling mediated by PAG protein is its double palmi- toylation. We investigate changes of the biophysical properties of both the lipid membrane and the peptide itself upon the incorporation of the palmitoyls. Em- ploying all atom MD simulations, we study inter- and intramolecular interactions as well as changes in membrane hydration, thickness, or lipid ordering. The second part of the thesis, realized in a direct collaboration with a phar- macological...

We employ the empirical potential function Airebo to computationally model free-standing Carbon-12 graphene in a classical setting. Our objective is to measure the mean square displacement (MSD) of atoms in the system for different average temperatures and Carbon-13 isotope concentrations. From results of the MSD we aim to develop a technique that employs Transmission Electron Microscopy (TEM), using high-angle annular dark filed (HAADF) detection, to obtain atomic-resolution images. From the thermally diffusive images, produced by the vibrations of atoms, we intent to resolve isotopes types in graphene. For this, we establish a relationship between the full width half maximum (FWHM) of real-space intensity images and MSD for temperature and isotope concentration changes. For the case of changes in the temperature of the system, simulation results show a linear relationship between the MSD as a function of increased temperature in the system, with a slope of 7.858×10-6 Å2/K. We also note a power dependency for the MSD in units of [Å2] with respect to the FWHM in units of [Å] given by FWHM(MSD)=0.20MSD0.53+0.67. For the case of increasing isotope concentration, no statistically significant changes to the MSD of 12C and 13C are noted for graphene systems with 2,000 atoms or more. We note that for the experimental replication of results, noticeable differences in the MSD for systems with approximately 320,000 atoms must be observable. For this, we conclude that isotopes in free-standing graphene cannot be distinguished using TEM.

Accuracy in turbulence modeling remains a hurdle in the widespread use of Computational Fluid Dynamics (CFD) as a tool for furthering fluids dynamics research. Meanwhile, computational power remains a significant concern for solving real-life wall-bounded flows, which portray a wide range of length and time scales. The tools for turbulence analysis at our disposal, in the decreasing order of their accuracy, include Direct Numerical Simulation (DNS), Large Eddy Simulation (LES), and Reynolds-Averaged Navier Stokes (RANS) based models. While DNS and LES would remain exorbitantly expensive options for simulating high Reynolds number flows for the foreseeable future, RANS is and continues to be a viable option utilized in commercial and academic endeavors. In the first part of the present work, flow over the back-step test case was solved, and parametric studies for various parameters such as re-circulation length (X_r), coefficient of pressure (C_p), and coefficient of skin friction (C_f) are presented and validated with experimental results. The back-step setup was chosen as the test case as turbulent modeling of flow past backward-facing step has been pivotal to understand separated flows better. Turbulence modeling is done on the test case using RANS (k-ε and k-ω models), and LES modeling, for different values of Reynolds number (Re ∈ {2, 2.5, 3, 3.5} × 10⁴) and expansion ratios (ER ∈ {1.5, 2, 2.5, 3}). The LES results show good agreement with experimental results, and the discrepancy between the RANS results and experimental data was highlighted. The results obtained in the first part reveal a pattern of under-prediction noticed with using RANS-based models to analyze canonical setups such as the backward-facing step. The LES results show close proximity to experimental data, as mentioned above, which makes it an excellent source of training data for the machine learning analysis outlined in the second part. The highlighted discrepancy and the inability of the RANS model to accurately predict significant flow properties create the need for a better model. The purpose of the second part of the present study is to make systematic efforts to minimize the error between flow properties from RANS modeling and experimental data, as seen in the first part. A machine learning model was constructed in the second part of the present study to predict the eddy viscosity parameter (μt) as a function of turbulent kinetic energy (TKE) and dissipation rate (ε) derived from LES data, effectively working as an ad hoc eddy-viscosity based turbulence model. The machine learning model does not work well with the flow domain as a whole, but a zonal analysis reveals a better prediction of eddy viscosity than the whole domain. Among the zones, the area in the vicinity of the re-circulation zone gives the best result. The obtained results point towards the need for a zonal analysis for the better performance of the machine learning model, which will enable us to improve RANS predictions by developing a reduced order turbulence model.

<p dir="ltr">DNA is organized into chromatin – a complex polymeric structure which stores information and controls gene expressions. Advancements in microscopy have enabled us to see chromatin in motion – which was previously thought to be static, and these motions contribute to various cellular functions. In my thesis I will demonstrate the molecular tools and biophysical approaches our lab has developed to uncover the mysteries of chromatin dynamics and structures at the single nucleosome resolution; I will also discuss how these new discoveries in chromatin enable us to explore its role in cell functions. This dissertation will first describe the technology advancement of live-cell image analysis; particularly, I will discuss the utilization of AI to improve the spatial and temporal resolution of chromatin imaging. Then I will show complex nature of chromatin where depending on the temporal scale of observation we see a different behavior and how computer simulations can see these differences. Following that, I will introduce our investigation on the role of chromatin motion in DNA damage and repair. Afterwards, I will discuss how the cell regulates its chromatin dynamics in response to the metabolism indicators AMPK (AMP-activated protein kinase). I will also show how chromatin motion and structure behave without the presence of key proteins such as RAD51 that aid in DNA damage. Finally I will go over future directions and improvements we can do to our current techniques to improve our understanding of chromatin’s role is various biological functions. We expect that the exploration of the spatiotemporal dynamics in live cells will facilitate the diagnosis, treatment, and prevention of cancers.</p>

La thermodiffusion, également appelé effet Soret, décrit le couplage entre les gradients de température et les flux massiques qui en résultent. Ce phénomène intervient dans de nombreux processus naturels et applications industrielles. En particulier, les réservoirs pétroliers sont sujets à ce phénomène impliquant des fluides multi constituants confinés dans une matrice poreuse et soumis à un gradient de température. Néanmoins, malgré beaucoup des progrès, il existe relativement peu de mesures fiables de ce phénomène et sa modélisation reste largement un problème ouvert. L’objectif principal de cette thèse s’inscrit dans ce cadre, à savoir développer une approche expérimental permettant de fournir des données de références sur la thermodiffusion notamment dans l’optique de quantifier l’effet de la pression sur cette dernière. Ainsi, durant cette thèse, nous avons développé une cellule de thermodiffusion en milieu libre qui permet d’étudier par shadowgraphie les fluctuations de non équilibre induites par effet Soret. L’appareil de mesure a ensuite été utilisé pour étudier deux mélanges binaires représentatifs de fluides pétroliers, à savoir le mélange équimassique tétraline/dodécane (en phase liquide) et le mélange dioxyde de carbone/méthane (en phases gaz et supercritique). En complément, des simulations de dynamique moléculaire ont été réalisées sur le mélange dioxyde de carbone/méthane. Par analyse dynamique des images de shadowgraphie nous avons pu déterminer les coefficients de diffusion et Soret en fonction de la pression pour le mélange tétraline/dodécane. Aux incertitudes près, nous observons une décroissance linéaire avec la pression pour ces coefficients. De plus nous avons observé l’effet du confinement de la cellule sur les fluctuations en très bon accord avec la théorie et les simulations. Pour le mélange dioxyde de carbone/méthane l’analyse dynamique a montré une cinétique difficilement accessible de par les limites physiques et informatiques du dispositif expérimental utilisé. L’analyse statique montre, quant à lui, une croissance rapide de l’amplitude des fluctuations avec la pression jusqu’à un seuil au-delà duquel elle décroît. Sur ce mélange les simulations de dynamique moléculaire ont montré un bon accord avec les prédictions théoriques. / Thermodiffusion, also called the Soret effect, describes the coupling between temperature gradient and resulting fluxes. This phenomenon is involved in a number of natural and industrial processes. In particular, multi components fluids in petroleum reservoirs are subjected to this phenomenon because of the geo-thermal gradient. Nevertheless, in spite of a lot of advances, there are few available data of this phenomenon and the establishment of a theoretical model, able to give a quantitative estimation of these transport coefficients whatever molecules in presence, is still an open question. The principal aim of this thesis is to develop an experimental approach allowing providing reference data on thermodiffusion as a function of the pressure. During this thesis, we developed a high pressure thermodiffusion cell in free medium, enabling us to study concentration non-equilibrium fluctuations induced by the Soret effect by means of shadowgraph optical technique. With this setup we investigated two binary mixtures representatives of petroleum fluids; namely the equimassic tetralin/dodecane mixture in liquid phase and the carbon dioxide/methane mixture in gaseous and super critical state. Furthermore, molecular dynamic simulations on the second mixture were performed. Using a dynamic image analysis, we have measured molecular diffusion and Soret coefficient for the tetralin/dodecane mixture. Within experimental uncertainties, we observed a linear decrease of these coefficients with the pressure. Furthermore, we were able to observe the effect of confinement (finite size effect induced by cell vertical boundary conditions) on fluctuation dynamics, in good agreement with calculations and simulations based on hydrodynamic fluctuation theory on similar solutal Rayleigh number. Concerning the carbon dioxide/methane mixture, the dynamic analysis revealed a kinetic too fast for our experimental apparatus. Conversely, static analysis revealed a rapid increase of the non-equilibrium fluctuation magnitude as a function of the pressure up to a threshold beyond which it decreases. On this mixture, performed molecular dynamic simulations provided results in good agreement with expected theoretical behaviour.