Дисертації з теми "Control phenomena"

Glioblastoma multiforme (GBM) is the most lethal primary central nervous system tumor, with median survival after diagnosis of less than 12 months because dissemination into the brain parenchyma limits the long-term effectiveness of surgical resection, and because GBM cells are resistant to radiation and chemotherapy. This sad dismal prognosis for patients with GBM emphasizes the need for greater understand of the fundamental biology of the disease. Invasion is one of the major causes of treatment failure and death from glioma, because disseminated tumor cells provide the seeds for tumor recurrence. Inflammation is increasingly recognized as an important component of invasion. In the brain, inflammation can occur by activation of microglia, the resident macrophages of the brain, or by tumor-associated blood macrophages. Therefore, we hypothesize that activity of the innate immune system in the brain can influence tumor progression by secreting cytokines such as Tumor Necrosis Factor alpha (TNF-α). In this study, we show that patient-derived glioma spheres undergo morphological changes in response to TNF‑α that are associated with changes in migration behavior in vitro. These morphological changes include appearance of tumor islands in site different from where the primary tumor cells were seeded. We further showed that TNF‑α treated cells significantly increased expression of cell adhesion molecules such as CD44 and VCAM-1. Furthermore, we demonstrate increased cell density also caused increased in expression of cell adhesion molecules. The extent to which these are recapitulated in vivo will be investigated.

Electrical motors are key to the growth of any modern society. In order to ensure optimal utilisation of the motors, the shaft speed and armature current must be controlled. Currently, the most efficient way of achieving both speed and current control in electrical motors is through power electronic switching, thus making the system both nonlinear and time varying. The combination of electric motors and control electronics is referred to as electric drives. Due to the inherent nonlinear nature of electrical drives, the system is prone to complex dynamical phenomena including bifurcations, chaos, co-existing attractors and fractal basin boundaries. The types of nonlinear phenomena that occur in some of the more common electrical drive systems, namely permanent magnet dc (PMDC) drives, series connected dc (SCDC) drives and switched reluctance motor (SRM) drives, are considered for analysis in this project. The nominal steady state behaviour of these drives is a periodic orbit with a mean value close to the reference value. But as some system parameters are being varied, the nominal orbit of the system referred to as the period-1 orbit, may lose its stability leading to the birth of new attracting orbit that is periodic, quasi-periodic or chaotic in nature. The most common technique for performing stability analysis of a periodic orbit is the Poincaré map approach, which has been successfully applied in DC-DC converters. This method involves reducing the continuous time dynamical system into a discrete time nonlinear iterative map and the periodic orbit into a fixed point. The stability of the periodic orbit then depends on the eigenvalue of the Jacobian matrix of the map evaluated at the fixed point. However, for some power electronic based system the nonlinear map cannot be derived in closed form due to the transcendental nature of the equation involved. In this project, the recently introduced Monodromy matrix approach is employed for the stability analysis of the periodic orbit in electrical drives. This method is based on Filippov’s method of differential inclusion and has been successfully applied in the stability analysis of periodic orbits in both low order and higher order DC-DC converters. This represents the first application of the technique in electrical drives. The Monodromy matrix approach involves computing the State Transition Matrix (STM) of the system around the nominal orbit including the STM at the switching manifold (sometimes referred to as the Saltation matrix). Also, by manipulating some of the parameters in the Saltation matrix, it is possible to control the instabilities and thus extend the system parameter range for nominal period-1 operation. The experimental validation of the nonlinear phenomena in a proportional integral (PI) controlled PMDC drive, which is absent in literature, is presented in this thesis. The system was implemented using dsPIC30F3010 which is a low cost and high performance digital signal controller.

The adsorption of metanil yellow [3-{{4-(phenylamino) phenyl}} benzene sulfonate] and colloidal silica on a commercially available, positively charge-modified nylon 66 membrane (N66 Posidyne) with an isoelectric point (IEP) of 7.6 was investigated. Challenge testing of N66 Posidyne with a 2.3 ppm colloidal silica dispersion has shown that the membrane adsorbed 0.015 μg of colloidal silica per cm². At a pH of 5.1, the adsorption of metanil yellow was found to increase with its solution concentration and reached a saturation value of 2.2 x 10¹⁴ ions/cm² at a solution concentration of 1.49 x 10⁻⁵M. A technique to incorporate positively charged groups onto the surface of microporous polypropylene and polyvinylidene fluoride membrane filters for the filtration of liquids used in the semiconductor industry has been developed using γ-irradiation. The electrical characteristics of prepared membranes were measured by streaming potential and dye challenge tests. The compatibility of these charge-modified membranes with ultrapure water was investigated. Results show that these charge-modified membranes are characterized by a positive zeta potential in the pH range from 4 to 9.3. From the dye challenge tests at a pH of 5.0, the density of positively charged sites on charge-modified membranes was calculated to be approximately five times larger than that of unmodified membranes. The modified membranes released less than 1 ppb of total organic carbon (TOC) into ultrapure water and thus appear to have potential for use in DI water system. The electrokinetic characteristics of silicon, silicon dioxide and silicon nitride wafers subjected to different cleaning procedures were measured using a streaming potential technique. A streaming potential cell for handling 5" wafers was designed and fabricated to make these measurements. The isoelectric point of silicon, silicon dioxide and silicon nitride was dependent on the cleaning method. Polystyrene latex (PSL) and aminopropyl/silica particle deposition from aqueous solutions onto silicon nitride was investigated and correlated with the electrokinetic potential data.

In this thesis different aspects of MagnetoHydroDynamic phenomena that limit plasma performance and confinement in toroidal pinch devices will be addressed. The thesis contains original work carried out in two different devices: the Joint European Torus (JET) tokamak, and the RFX-mod Reversed Field Pinch (RFP), which are both the largest magnetic confinement devices in operation for their configuration. In the JET device focus was put on Neoclassical Tearing Modes (NTMs), which are resistive instabilities that tear magnetic field lines and reconnect them forming magnetic field islands. With the aim of studying the NTM physics, two radial localization techniques for magnetic islands have been developed, and their outputs have been compared with q profiles obtained with a Motional Stark Effect diagnostic. One of the studied localization techniques has been also used in a non conventional way to reconstruct the NTM m number spectrum, and to extract new information on the tearing-kink structure of the mode. The impact of NTMs on JET advanced tokamak discharges has been documented, with the ultimate aim of quantifying the loss in plasma confinement induced by the mode as a function of the island radial localization. Other chirping modes were encountered in JET, which are thought to be driven by energetic particles and dubbed q=2 fishbones. Their experimental signature and impact on the plasma discharge have been studied. In the RFX-mod device the addressed topic was the study and control of Resistive Wall Modes (RWMs) in RFP configuration. The RWM is a branch of the ideal kink mode that grows on the time scale of current diffusion in the wall. First of all a RWM growth rate database in RFX-mod was created, and it was subsequently used as a standard growth rate reference in the analysis of the couplings between different m and n harmonics. Advanced feedback control topics were addressed as well, such as the development and benchmark of a dynamical RWM control simulator, and the RWM stabilization in control experiments using various sets of active saddle coils.
In questa tesi saranno affrontati i diversi aspetti dei fenomeni magnetoidrodinamici che limitano le prestazioni ed il confinamento degli esperimenti toroidali di tipo pinch. La tesi contiene il lavoro originale portato avanti in due diverse macchine, che sono entrambe i più grandi esperimenti a confinamento magnetico in operazione per rispettive configurazioni: il tokamak Joint European Torus (JET) ed il Reversed Field Pinch (RFP) RFX-mod. Nel tokamak JET l’attività di ricerca si è concentrata sui Neoclassical Tearing Modes (NTM), che sono delle instabilità resistive che rompono le linee di campo magnetico e le riconnettono, formando delle isole di campo magnetico. Allo scopo di studiare la fisica dei NTM, sono state sviluppate due tecniche per la localizzazione radiale delle isole magnetiche, ed i risultati prodotti sono stati confrontati con i profili radiali di q ottenuti per mezzo della diagnostica Motional Stark Effect. Una delle tecniche di localizzazione studiate è stata anche usata in modo non convenzionale per ricostruire lo spettro del numero d’onda m poloidale dei NTM, e per ricavare informazioni sulla struttura kink-tearing di queste instabilità. E’ stato pure documentato l’impatto dei NTM sulle scariche advanced tokamak, allo scopo di quantificare il peggioramento nel confinamento del plasma che queste inducono, in funzione della localizzazione radiale dell’isola magnetica da loro generata. Durante l’attività su JET sono state incontrate anche delle altre instabilità, che si ritiene siano eccitate dalla popolazione di particelle veloci nel plasma, e che sono soprannominate fishbone q = 2. Sono state caratterizzate le loro evidenze sperimentali ed il loro impatto sugli impulsi di plasma. Nel RFP RFX-mod il lavoro è stato concentrato sullo studio e controllo dei Resistive Wall Modes (RWM), che sono una branca dei modi kink ideali che cresce selle scale dei tempi della diffusione delle correnti all’interno delle strutture conduttrici attorno al plasma. Inizialmente è stato creato un database contenente i tassi di crescita di tutte le instabilità di tipo RWM rilevate in RFX-mod, ed il database è stato in seguito usato come riferimento nell’analizzare gli accoppiamenti tra le diverse armoniche m ed n dei RWM. Sono stati affrontati anche problemi di controllo in feedback avanzato, come lo sviluppo ed il benchmark di un simulatore dinamico del controllo attivo RWM, e la sperimentazione del controllo RWM usando diversi gruppi di bobine attive.

This thesis is concerned with enhancing our understanding, and hence our control over, the apparently random fluctuations of the time series of business variables in a framework of analysis which appeals to management's mental world of 'common sense' and 'causality'. Theoretical models of (i) a cost control system in a standard costing system setting, and (ii) a hypothetical firm and its business environment were proposed. They were constructed by referring to the concept of 'control' in organizations, to business system modelling, and to dynamical systems theory. The respective target variables of the models are the controlled cost item and the cash account balance. Various modes of steady state behaviour of the target variables were obtained by performing simulation experiments. The subsequent data analysis was conducted mainly in the framework of dynamical systems theory. The major findings of this research are consistent with the hypotheses that: 1. there exist deterministic explanations for the apparently random fluctuations in the behaviour of the business variables, 2. these deterministic explanations could enable managers to modify their control systems so as to reduce the apparently random fluctuations in the behaviour of the business variables.

Viscous phenomena can be used to aid in the locomotion and control of robotic systems. With the aid of Lagrangian reduction techniques, it is shown that dissipation can be used to model nonholonomic, holonomic, and kinematically constrained systems. This is shown theoretically, analytically, and numerically for a class of robotic systems. Using techniques from geometric mechanics, control problems for novel planar robots that incorporate nonholonomic constraints, dissipation, and geometric phase are explored. A robotic fish is introduced, and experiments demonstrate it can harvest energy from fluid vortices to assist in propulsion, consistent with geometric models in the literature. Experimental fluid vortices are also generated and characterized with the aid of particle image velocimetry.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 126-132).
The primary goal of this thesis is to study transmission line reactance tweaking, as a mechanism for both post-disturbance control and pre-disturbance resilience enhancement in a transmission network, and develop an optimization framework for evaluating the efficacy of this mechanism in both scenarios. We start by developing a mixed-integer linear programming (MILP) formulation for tracking the redistribution of direct current (DC) flows and the graph-theoretic evolution of network topology over the course of cascading failures. Next, we propose a min-max setup for studying the impact of post-disturbance reactance tweaking on the resilience of the system to a worst-case N-k disturbance and devise a MILP reformulation scheme for the underlying bilevel nonconvex mixed-integer nonlinear program (MINLP) to facilitate the computation of its optimal solution. We then develop a MILP framework for computing the exact value of a tight upper bound on the efficacy of post-disturbance reactance tweaking among the set of all possible Nk disturbances for a given k and a given bus load scenario. Our numerical case study suggests that post-disturbance reactance tweaking, even on only a small number of lines, can considerably reduce the amount of load shed in some scenarios in the tested system. As for pre-disturbance resilience enhancement, we develop a MILP reformulation for approximating the bilevel MINLP that seeks to assess the efficacy of pre-disturbance reactance tweaking in reducing the number of lines that will fail over the propagation of cascading failures in the event of a worst-case-scenario N-k disturbance. We also give a MILP framework for computing an approximate upper bound on the efficacy of this mechanism among the set of all N-k contingencies for a given k. Our numerical case study suggests that pre-disturbance reactance tweaking on a few transmission lines can, in some cases, prevent the failure of multiple transmission lines over the course of cascading failures in the tested system.
by Ali Faghih.
Ph. D.

The A-type lamins are intermediate filament proteins that constitute a major part of the eukaryotic nuclear lamina—a tough, polymerized, mesh lining of the inner nuclear membrane, providing shape and structural integrity to the nucleus. Lamin A (LA) filaments also permeate the nucleoplasm, providing additional structural support, but also scaffolding numerous tethered molecules to stabilize, organize, and facilitate molecular interactions to accomplish critical functions of cellular metabolism. Over the past 2 decades, much attention has been focused on roles of LA in maintenance of nuclear structural integrity. Only since the late 1990s have scientists discovered the devastating effects of LA gene (LMNA) mutations, as they have associated hundreds of LMNA mutations to a large group of diseases, called laminopathies, with a broad spectrum of phenotypes, ranging from skeletal, muscular, and neurological defects, to defective lipid storage, to accelerated aging phenotypes in diseases called progerias. Recent advances demonstrate LA regulatory functions include cell signaling, cell cycle regulation, transcription, chromatin organization, viral egress, and DNA damage repair. Amidst the flurry of fascinating research, only recently have researchers begun to focus attention on the different isoforms that exist for LA, a precursor form among them. LA is initially synthesized as Prelamin A (PreA), and undergoes a series of modifications that truncate the protein to produce “mature” LA. Existence of the precursor form, and its complex maturation pathway, have puzzled researchers since their realization. With a pattern of expression related to cell cycle phase, we hypothesized a role for PreA in cell cycle control. To investigate, we have performed array studies to assess gene expression effects at the levels of transcript expression, protein expression, and phosphorylation modification status. Here, we present evidence for a PreA-mediated program of cell cycle regulatory gene and protein expression modulation. Implicated pathways include RB-E2F, p53, p27Kip1, FoxOs, p300, and the Cyclins, with additional evidence indicating a role for the Pin1 prolyl isomerase in mediating PreA regulation of the cell cycle.

Les phénomènes instationnaires dans les cavités rotor/stator sont connus pour être la source de dangereuses vibrations dans les turbopompes spatiales. Bien que plusieurs mesures palliatives aient été prises en comptes durant les phases de conception, des campagnes d’essais ont mis en évidence de fortes oscillations des écoulements internes pouvant menacer le moteur cryogénique des lanceurs. Aujourd’hui, l’origine de ce phénomène, appelé «bandes de pression », est peu compris et difficile à prédire numériquement. L’objectif de cette thèse est d’analyser les mécanismes physiques de ce phénomène afin d’apporter des solutions pour le contrôler. Pour répondre à cette problématique, deux types de configuration sont étudiés: une cavité rotor/stator annulaire et une cavité de turbopompe spatiale. Les couches limites tournantes dans ces cavités sont connues pour être 3D et réceptives à plusieurs types d’instabilités prenant entre autre la forme de spirales ou d’anneaux. Les simulations basées sur la moyenne de Reynolds (RANS) ont par le passé échoué à prédire ce type d’écoulement. Cependant, les Simulations aux Grandes Echelles (SGE) se sont avérées être une alternative à ce problème et sont donc été utilisées tout au long de cette thèse. Des Densités Spectrales de Puissance (DSP) ainsi que des Décompositions modales dynamiques (DMD) appliqués aux résultats SGE, ont permis de montrer que le phénomène de bandes de pression est visible également dans une cavité annulaire de type académique et composé de trois modes dictant toute la dynamique du système. Afin d’étudier les interactions de ces modes, une nouvelle méthode appelée Dynamic Mode Tracking/Control (DMT/DMTC) a été proposée durant cette these. La DMT est construite pour extraire des structures cohérentes dans une simulation SGE. De plus, en ajoutant un terme de relaxation dans les équations de Navier-Stokes couplées avec la DMT, sa variante appelée DMTC permet de contrôler et de suivre en temps réelle un ou plusieurs modes et donc de pouvoir analyser de possibles interactions. Appliqué à la cavité académique annulaire, cette méthode a permis de montrer que le mode basse fréquence est généré dans l’écoulement par le mode dominant du système. Pour aller plus loin, des analyses de stabilité linéaire de type global (GLSA), sont effectuées sur la cavité académique. Grâce à des méthodes adjointes, la GLSA a permis de mettre en avant l’origine spatiale de chacun des trois modes. Deplus, afin de mettre en place des stratégies de contrôle, la sensibilité à la modification de l’écoulement de base, obtenue par GLSA, a permis d’identifier la région à modifier pour stabiliser un mode donné ou décaler sa fréquence. Appliqué au cas académique, il est montré et que contrôler la couche limite du stator est le moyen le plus efficace de supprimer le phénomène de bandes de pression à travers des injections/aspirations. Pour finir, le phénomène de bandes de pression est analysé dans une cavité de turbopompe spatiale. En particulier, la sensibilité de ce phénomène aux changements géométriques est abordée à travers deux configurations: une première sans les aubes du stator de la turbopompe et une deuxième avec. Bien que les aubes génèrent un écoulement complexe, des fréquences similaires de fluctuation de pression sont retrouvées dans les deux configurations avec cependant des nombres azimutaux caractéristiques différents. En se basant sur les études faites sur la cavité académique, une version adaptée de GLSA pour la dynamique de la turbopompe permet de mettre en avant que malgré que le phénomène de bandes pression soit particulièrement présent dans la veine de la turbopompe, la source de ces modes se situe dans les cavités inférieures entre le rotor et le stator. De plus les résultats de GLSA mettent en avant que deux moyens de contrôle pourraient être appliqués pour supprimer le phénomène de bandes de pression dans ce cas industriel: modifier le joint d’étanchéité ou modifier la fuite du moyeu
Unsteady phenomena in rotor/stator cavity are well known to be the source of dangerous vibrations in space turbopump. Even though many palliative measures have been taken during their design, experimental campaigns often reveal high flow oscillations that can jeopardize turbomachinery components and even the rocket engine. Today, the origin of such flow instabilities usually called ’pressure band phenomenon’(PBP) is not well understood and difficult to predict numerically. The main goal of this thesis is to investigate such phenomenon mechanism to find technical solutions so as to control it. This problematic is addressed here trough two types of configuration: an academic rotor/stator cavity and a space turbopump cavity. When it comes to cavity flows, their rotating boundary layers are known to be three dimensional and receptive to several instabilities taking the form of spirals or annuli. Reynolds Averaged Navier-Stokes Simulations (RANS)failed to predict such unsteady systems. However, Large Eddy Simulation (LES) proved to be a relevant alternative in many similar applications and is therefore chosen for the present work. Using Power Spectral Analysis (PSD) and Dynamic Mode Decomposition (DMD) on LES predictions, one shows that the PBP is retrieved in an annular smooth rotor/stator cavity and it is composed of three modes driving all the system dynamics. To investigate these mode organization and their possible interactions, a new tool called Dynamic Mode Tracking /Control (DMT/DMTC) is introduced. DMT is constructed so as to extract "on-thefly" flow coherent structures with a given frequency on the basis of LES. Furthermore, augmenting the Navier-Stokes equations with a relaxation term coupled to DMT, DMTC allows to control and follow the evolution of a controlled mode as well as non controlled ones and thereby observe interactions. This strategy after validation is applied to the annular rotating cavity and shows that the low frequency mode is generated by the dominant mode of the system. To go further, Global Linear Stability Analysis (GLSA) augmented with adjoint methods is used to shed some light on all mode origins and points out that the low frequency and dominant modes are coming from the stationary boundary layer. In order to set up control strategies, the GLSA framework is further developed introducing the concept of the sensitivity to base flow modifications which gives the location where the flow should be modified if one wants to stabilize or at least shift a frequency mode. Applied to the academic cavity, one shows that contrary to most studies in the literature, controlling the stator boundary layer is the more efficient way to damp the PBP through suction/injection devices. Finally, gathering all the previous understanding of this flow, the LES framework enables to validate the control strategies proposed and to stabilize the PBP for very low suction amplitudes. To finish, the PBP is analyzed in real space turbompump cavities. In particular, the sensitivity of this specific phenomenon to geometry changes is investigated through two configurations: one without and one with the blades of the stator of the turbopump. Even though the introduction of the blades in the LES creates a more complex flow with the presence of shocks, similar pressure fluctuation spectra are retrieved in both configurations but with azimuthal wavenumber modes that are shifted. Following the studies on the academic cavity, an adapted GLSA to the non-linear dynamics of the turbopump enables to point out that even though the PBP modes are particularly marked in the mainstream of the system, the source of these modes is located in the subcavity in the rotor-stator wheel space. In particular, GLSA results indicate that two possible ways to control the phenomenon are possible: modifying the flow around the seal rim and or modifying the leak around the hub

Switched systems belong to a special class of hybrid systems, which consist of a collection of subsystems described by continuous dynamics together with a switching rule that specifies the switching between the subsystems. Such systems can be used to describe a wide range of practical applications, such as orbital transfer of satellites, auto-driving design, communication security, financial investment, neural networks and chaotic systems, just to name a few. For these switched systems, the occurrence of impulses and delay phenomena cannot be avoided. For example, in some circuit systems, switching speeds of amplifiers within the units’ individual circuits are finite, and hence causing delays in the transmission of signals. The abrupt changes in the voltages produced by faulty circuit elements are exemplary of impulsive phenomena. On the other hand, it is well known that stability is one of the most important issues in real applications for any dynamical system, and there is no exception for switched systems, switched systems with impulses, or delayed switched systems.With the motivations mentioned above, we present, in this thesis, new developments resulting from our work on fundamental stability theory and design methodologies for stabilizing controllers of several types of switched systems with impulses and delays. These systems and their practical motivations are first discussed in Chapter 1. Brief reviews on existing results which are directly relevant to the subject matters of the thesis are also given in the same chapter.In Chapter 2, we consider a class of impulsive switched systems with time- invariant delays and parameter uncertainties. New sufficient stability conditions are obtained for these impulsive delayed switched systems. For illustration, a numerical example is solved using the proposed approach.In Chapter 3, new asymptotic stability criteria, expressed in the form of linear matrix inequalities, are derived using the Lyapunov-Krasovskii technique for a class of impulsive switched systems with time-invariant delays. These asymptotic stability criteria are independent of time delays and impulsive switching intervals. A design methodology is then developed for the construction of a feedback controller which asymptotically stabilizes the closed-loop system. A numerical example is solved using the proposed method.In Chapter 4, new asymptotic stability criteria, expressed in the form of linear matrix inequalities, and a design procedure for the construction of a delayed stabilizing feedback controller are obtained using the receding horizon method for a class of uncertain impulsive switched systems with input delay. For illustration, a numerical example is solved using the proposed method.In Chapter 5, we consider the stabilization problem for cellular neural networks with time delays. Based on the Lyapunov stability theory, we obtain new sufficient conditions for asymptotical stability of the delayed cellular neural networks and devise a computational procedure for constructing impulsive feedback controllers which stabilize the delayed cellular neural networks. A numerical example is given, demonstrating the effectiveness of the proposed method.In Chapter 6, we consider a class of H∞ optimal control problems with systems described by uncertain impulsive differential equations. A new design method for the construction of feedback control laws which asymptotically stabilize the uncertain closed-loop systems is obtained. Furthermore, it is shown that the H∞ norm-bounded constraints on disturbance attenuation for all admissible uncertainties are satisfied. New sufficient conditions, expressed as linear matrix inequalities, for ensuring the existence of such a control law are presented. A numerical example is solved, illustrating the effectiveness of the proposed method.In Chapter 7, we conclude the thesis by making some concluding remarks and giving brief discussions on topics for further research.

Microfluidic and nanofluidic technology is revolutionizing experimental practices in analytical chemistry, molecular biology and medicine. Indeed, the development of systems of small dimensions for the processing of fluids heralds the miniaturization of traditional, cumbersome laboratory equipment onto robust, portable and efficient microchip devices (similar to the electronic microchips found in computers). Moreover, the conjunction of scale between the smallest man-made device and the largest macromolecules evolved by Nature is fertile ground for the blooming of our knowledge about the key processes of life. In fact, the conjunction is threefold, because modern computational resources also allow us to contemplate a rather explicit modelling of physical systems between the nanoscale and the microscale. In the five articles comprising this thesis, we present the results of computer simulations that address specific questions concerning the operation of two different model systems relevant to the development of small-scale fluidic devices for the manipulation and analysis of biomolecules. First, we use a Bond-Fluctuation Monte Carlo approach to study the electrophoretic drift of macromolecules across an entropic trap array built for the length separation of long, double-stranded DNA molecules. We show that the motion of the molecules is consistent with a simple balance between electric and entropic forces, in terms of a single characteristic parameter. We also extract detailed information on polymer deformation during migration, predict the separation of topoisomers, and investigate innovative ratchet driving regimes. Secondly, we present theoretical derivations, numerical calculations and Molecular Dynamics simulation results for an electrolyte confined in a capillary of nanoscopic dimensions. In particular, we study the effectiveness of neutral grafted polymer chains in reducing the magnitude of electroosmotic flow (fluid flow induced by an external electric field). Our results constitute the first independent, quantitative verification of theoretical scaling predictions for the coupling between grafted macromolecules and electroosmotic flow. Such simulations will contribute to the rationalization of the existing empirical knowledge about flow control with polymer coatings.

Recently, the wavy leading edge airfoils, inspired by the humpback whale´s flipper, have been investigated, as flow control mechanisms, at low Reynolds numbers in order to improve aerodynamic performance in this particular flow regime. The overall aim of this work is to investigate the airfoil geometric effects on wavy leading edge phenomena in the low Reynolds number regime. Experimental investigations were carried out correlating force measurements with mini-tuft and oil visualizations in order to understand the airfoil thickness effects on wavy leading edge phenomena. Three sets of airfoil thickness were tested (NACA 0012, NACA 0020 and NACA 0030), each set consisting of smooth plus three wavy configurations (A=0.11c, ?=0.40c; A=0.03c, ?=0.40c and A=0.03c, ?=0.11c); Reynolds number was varied between 50,000 and 290,000. The results present many findings that were not possible in previous studies due the fact that these investigations were constrained to specific geometries and/or flow conditions. At higher Reynolds number, the decrease in airfoil thickness leads the airfoils to leading edge stall characteristics causing the lowest aerodynamic deterioration for the thinnest wavy airfoil as compared to smooth configuration in the pre-stall regime. In addition, the results show impressive tubercle performance in the lowest Reynolds number. For any tubercle geometry and airfoil thickness, the wavy leading edge airfoils present higher maximum lift values as compared to smooth configurations showing an unprecedented increase in performance for a full-span model tested in the literature. The flow visualizations present two flow mechanisms triggered by secondary flow: three-dimensional laminar separation bubbles and vortical structures. Regarding three-dimensional laminar bubbles, the results confirm some of the few previous experimental and numerical studies, and presents for the first time these structures as a very efficient flow control mechanism in the post-stall regime justifying the impressive increase in maximum lift in the lowest Reynolds number. Besides that, two characteristics of laminar bubbles, \"tipped-bubbles\" and \"elongated-bubbles\", are identified with different effects in the pre-stall regime. This thesis presents higher tubercle performance for thinner airfoils (NACA 0012) and/or lower Reynolds number conditions (Re=50,000) showing clearly that an optimum performance lead the \"tubercles\" to operate under conditions of leading edge flow separation conditions. Therefore, a design space for tubercles conducted to leading edge stall characteristics confirming the hypothesis of Stanway (2008) eight years before.
Recentemente, aerofólios com bordo de ataque ondulados, inspirados na nadadeira da baleia jubarte, tem sido investigados como mecanismo de controle de escoamento para baixo número de Reynolds com a finalidade de se aumentar o desempenho aerodinâmico neste específico regime de escoamento. O objetivo geral deste trabalho é investigar os efeitos geométricos do aerofólio nos fenômenos do bordo de ataque ondulado na condição de baixo número de Reynolds. Investigações experimentais foram realizadas correlacionando medições de forças com visualizações de lã e óleo a fim de compreender os efeitos da espessura do aerofólio sobre os fenômenos de bordo de ataque ondulado. Três conjuntos de espessura de aerofólios foram testados (NACA 0012, NACA 0020 e NACA 0030) na faixa de número de Reynolds entre 50,000 e 290,000, onde cada conjunto tem um aerofólio liso e três ondulados (A = 0.11c, ? = 0.40c; A = 0.03c, ? = 0.40c e A = 0.03c, 0.11c ? =0.11c). O dados experimentais mostram importantes resultados que não foram possíveis em estudos anteriores devido às investigações serem restritas à geometria ou/e condição de escoamento específicas. O resultados de medida de força mostram que a diminuição da espessura do aerofólio conduz às características de separação de escoamento de bordo de ataque que causam menor deterioração aerodinâmica nos aerofólios ondulados finos quando comparados aos lisos no regime de pré-stall. Além disso, os resultados mostram um desempenho destacado do bordo de ataque ondulado para condição de menor número de Reynolds. Em quaisquer espessuras de aerofólio, os bordos ondulados apresentam valores de sustentação máxima maiores quando comparado aos aerofólios lisos mostrando assim resultado inédito na literatura para modelos ondulados bi-dimensionais. As visualizações de óleo evidenciaram dois mecanismos de controle de escoamento desencadeadas pelo escoamento secundário: bolhas de separação laminar tridimensionais e estruturas vorticais. Os resultados confirmam alguns poucos estudos experimentais e numéricos anteriores relacionadas com bolhas tridimensionais, e apresenta pela primeira vez estas estruturas como um mecanismo muito eficiente de controle de escoamento em regime de pós-stall justificando o aumento de máxima sustentação para o menor número de Reynolds. Adicionalmente, foram identificadas duas estruturas de bolhas tridimensionais nomeados aqui como \"bolhas com pontas\" e \"bolhas alongadas\" que causam distintos efeitos no regime de pré-stall. Esta tese apresenta como resultado maior desempenho para aerofólios ondulados com menor espessura (NACA 0012) e/ou para condições de menor número de Reynolds (Re=50,000)mostrando claramente que estas características levam as ondulações a operarem em condições de stall de bordo de ataque assim tendo um desempenho superior. Portanto, um espaço de projeto para tubérculos conduz às características de stall de bordo de ataque confirmando a suposição de Stanway (2008) oitos anos antes.

Dans un souci d’optimisation des fours industriels et de réduction des émissions de gaz à effet de serre,l’oxy-combustion est considérée comme l’une des solutions d’avenir. Les conditions existantes dans les chambres d’oxycombustion créent une interaction forte entre les différents phénomènes : Combustion,turbulence et transferts de chaleur. Pour mieux dimensionner les configurations futures il est nécessaire de pouvoir étudier la physique qui y règne, et ce pour un coût et un temps de retour raisonnables. De tels études nécessitent l’emploi d’outils de simulation de haute fidélité,et afin de modéliser les interactions inter-phénomènes à un coût acceptable le couplage de codes est utilisé. C’est avec cet objectif que les travaux présentés dans ce manuscrit se concentrent sur la mise au point d’une méthodologie de couplage entre codes d’écoulements réactifs et de transfert de chaleur dans les parois pour la réalisation de simulations de haute-fidélité massivement parallèles prédictives des chambres futures
Oxycombustion is seen as one mean to attain the wished goals in terms of efficiency optimisation and Greenhouse Effect Gases emissions reduction for industrial furnaces. The extreme operating conditions, high pressure and temperature, lead to a strong interaction between the different phenomena which take place inside the combustion chambe r: Combustion, turbulence and heat transfer. To better design these futur oxyfuel processes, a mean to study the related physics with a reasonable computational cost and return time. Such studies require the use of high-fidelity numerical resolution tools, and in order to model the multi-physics interaction in a cost efficient way, code coupling. The operating conditions being extreme : High pressure and temperature, a strong interaction exists between the different phenomena occuring inside the chamber. To better understand the physics inside oxycombustion chambers,a multiphysics high-fidelity simulation methodology is developped

The cardiovascular regulation undergoes wide changes in the different states of sleepwake cycle. In particular, the relationship between spontaneous fluctuations in heart period and arterial pressure clearly shows differences between the two sleep states. In non rapid-eye-movement sleep, heart rhythm is under prevalent baroreflex control, whereas in rapid-eye-movement sleep central autonomic commands prevail (Zoccoli et al., 2001). Moreover, during rapid-eye-movement sleep the cardiovascular variables show wide fluctuations around their mean value. In particular, during rapid-eyemovement sleep, the arterial pressure shows phasic hypertensive events which are superimposed upon the tonic level of arterial pressure. These phasic increases in arterial pressure are accompanied by an increase in heart rate (Sei & Morita, 1996; Silvani et al., 2005). Thus, rapid-eye-movement sleep may represent an “autonomic stress test” for the cardiovascular system, able to unmask pathological patterns of cardiovascular regulation (Verrier et al. 2005), but this hypothesis has never been tested experimentally. The aim of this study was to investigate whether rapid-eye-movement sleep may reveal derangements in central autonomic cardiovascular control in an experimental model of essential hypertension. The study was performed in Spontaneously Hypertensive Rats, which represent the most widely used model of essential hypertension, and allow full control of genetic and environmental confounding factors. In particular, we analyzed the cardiovascular, electroencephalogram, and electromyogram changes associated with phasic hypertensive events during rapid-eyemovement sleep in Spontaneously Hypertensive Rats and in their genetic Wistar Kyoto control strain. Moreover, we studied also a group of Spontaneously Hypertensive Rats made phenotypically normotensive by means of a chronic treatment with an angiotensin converting enzyme inhibitor, the Enalapril maleate, from the age of four weeks to the end of the experiment. All rats were implanted with electrodes for electroencephalographic and electromyographic recordings and with an arterial catheter for arterial pressure measurement. After six days for postoperative recovery, the rats were studied for five days, at an age of ten weeks.The study indicated that the peak of mean arterial pressure increase during the phasic hypertensive events in rapid-eye-movement sleep did not differ significantly between Spontaneously Hypertensive Rats and Wistar Kyoto rats, while on the other hand Spontaneously Hypertensive Rats showed a reduced increase in the frequency of theta rhythm and a reduced tachicardia with respect to Wistar Kyoto rats. The same pattern of changes in mean arterial pressure, heart period, and theta frequency was observed between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate. Spontaneously Hypertensive Rats do not differ from Wistar Kyoto rats only in terms of arterial hypertension, but also due to multiple unknown genetic differences. Spontaneously Hypertensive Rats were developed by selective breeding of Wistar Kyoto rats based only on the level of arterial pressure. However, in this process, multiple genes possibly unrelated to hypertension may have been selected together with the genetic determinants of hypertension (Carley et al., 2000). This study indicated that Spontaneously Hypertensive Rats differ from Wistar Kyoto rats, but not from Spontaneously Hypertensive Rats treated with Enalapril maleate, in terms of arterial pH and theta frequency. This feature may be due to genetic determinants unrelated to hypertension. In sharp contrast, the persistence of differences in the peak of heart period decrease and the peak of theta frequency increase during phasic hypertensive events between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate demonstrates that the observed reduction in central autonomic control of the cardiovascular system in Spontaneously Hypertensive Rats is not an irreversible consequence of inherited genetic determinants. Rather, the comparison between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate indicates that the observed differences in central autonomic control are the result of the hypertension per se. This work supports the view that the study of cardiovascular regulation in sleep provides fundamental insight on the pathophysiology of hypertension, and may thus contribute to the understanding of this disease, which is a major health problem in European countries (Wolf-Maier et al., 2003) with its burden of cardiac, vascular, and renal complications.

The cardiovascular regulation undergoes wide changes in the different states of sleepwake cycle. In particular, the relationship between spontaneous fluctuations in heart period and arterial pressure clearly shows differences between the two sleep states. In non rapid-eye-movement sleep, heart rhythm is under prevalent baroreflex control, whereas in rapid-eye-movement sleep central autonomic commands prevail (Zoccoli et al., 2001). Moreover, during rapid-eye-movement sleep the cardiovascular variables show wide fluctuations around their mean value. In particular, during rapid-eyemovement sleep, the arterial pressure shows phasic hypertensive events which are superimposed upon the tonic level of arterial pressure. These phasic increases in arterial pressure are accompanied by an increase in heart rate (Sei & Morita, 1996; Silvani et al., 2005). Thus, rapid-eye-movement sleep may represent an “autonomic stress test” for the cardiovascular system, able to unmask pathological patterns of cardiovascular regulation (Verrier et al. 2005), but this hypothesis has never been tested experimentally. The aim of this study was to investigate whether rapid-eye-movement sleep may reveal derangements in central autonomic cardiovascular control in an experimental model of essential hypertension. The study was performed in Spontaneously Hypertensive Rats, which represent the most widely used model of essential hypertension, and allow full control of genetic and environmental confounding factors. In particular, we analyzed the cardiovascular, electroencephalogram, and electromyogram changes associated with phasic hypertensive events during rapid-eyemovement sleep in Spontaneously Hypertensive Rats and in their genetic Wistar Kyoto control strain. Moreover, we studied also a group of Spontaneously Hypertensive Rats made phenotypically normotensive by means of a chronic treatment with an angiotensin converting enzyme inhibitor, the Enalapril maleate, from the age of four weeks to the end of the experiment. All rats were implanted with electrodes for electroencephalographic and electromyographic recordings and with an arterial catheter for arterial pressure measurement. After six days for postoperative recovery, the rats were studied for five days, at an age of ten weeks.The study indicated that the peak of mean arterial pressure increase during the phasic hypertensive events in rapid-eye-movement sleep did not differ significantly between Spontaneously Hypertensive Rats and Wistar Kyoto rats, while on the other hand Spontaneously Hypertensive Rats showed a reduced increase in the frequency of theta rhythm and a reduced tachicardia with respect to Wistar Kyoto rats. The same pattern of changes in mean arterial pressure, heart period, and theta frequency was observed between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate. Spontaneously Hypertensive Rats do not differ from Wistar Kyoto rats only in terms of arterial hypertension, but also due to multiple unknown genetic differences. Spontaneously Hypertensive Rats were developed by selective breeding of Wistar Kyoto rats based only on the level of arterial pressure. However, in this process, multiple genes possibly unrelated to hypertension may have been selected together with the genetic determinants of hypertension (Carley et al., 2000). This study indicated that Spontaneously Hypertensive Rats differ from Wistar Kyoto rats, but not from Spontaneously Hypertensive Rats treated with Enalapril maleate, in terms of arterial pH and theta frequency. This feature may be due to genetic determinants unrelated to hypertension. In sharp contrast, the persistence of differences in the peak of heart period decrease and the peak of theta frequency increase during phasic hypertensive events between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate demonstrates that the observed reduction in central autonomic control of the cardiovascular system in Spontaneously Hypertensive Rats is not an irreversible consequence of inherited genetic determinants. Rather, the comparison between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate indicates that the observed differences in central autonomic control are the result of the hypertension per se. This work supports the view that the study of cardiovascular regulation in sleep provides fundamental insight on the pathophysiology of hypertension, and may thus contribute to the understanding of this disease, which is a major health problem in European countries (Wolf-Maier et al., 2003) with its burden of cardiac, vascular, and renal complications.

The demand for high performance electronic devices is ever increasing in today's world with advent of digital technology in every field. In order to support this fast paced growth and incursion of digital technology in society, smarter, smaller integrated circuits are required at a lower cost. This primary requirement drives semiconductor industries towards the integration of larger number of smaller transistors on a given circuit area. The past decades have seen a rapid evolution of material processing and fabrication techniques, as focus shifts from submicron to sub-nanometer length scales in device configuration. As the functional feature size of an integrated circuit decreases, the threshold of defect causing impurities rises drastically. Huge amount of resources are spent in downstream and upstream processing in order to restore system from contamination upsets and in the upkeep of Ultra-High-Purity (UHP) process streams to meet these stringent requirements. Contamination once introduced into the system also drastically reduces process yield and throughput resulting in huge losses in revenue. Regular UHP fluid distribution system maintenance as well as restorative operations involve a purging operation typically known as Steady State Purge (SSP). This purge operation involves large amount of expensive UHP gas and time. Depending on the scale of the system and type of process involved this results in significant tool, process downtimes and can have a wide range of environment, health and safety (ESH) ramifications. A novel purge process, referred to as Pressure Cyclic Purge (PCP) was studied for establishing gas phase contamination control in UHP applications. In understanding the basic mechanism of this technique and to analyze its extent of application in aiding purging operations, a coupled approach involving experimental investigation and computational process modelling was used. Representative and generic distribution sections such as main supply lines and sections with laterals were contaminated with a known amount of moisture as impurity. The dynamics of the impurity transport through the system from purging with SSP as well as PCP was captured by a highly sensitive analyzer. The surface interactions between the moisture and EPSS were characterized in terms of adsorption and desorption rate constants and surface site density. A computational process model trained using experimental data was then validated and used to study the steady and cyclic purge mechanisms and predict complex purge scenarios. Industrially relevant and applicable boundary conditions and system definitions were used to increases the utility of the computational tool. Although SSP compared closely with PCP on simple systems without laterals, a drastic difference in dry-down efficiency was noticed in systems with dead volumes in the form of capped laterals. Studies on system design parameters revealed that the disparity in performance was observed to increase with larger number and surface area of dead volumes, opening a path to critical understanding of the differences in process mechanisms. Beneficial transient pressure gradient induced convective flow in the dead volumes during cyclic purge was identified to be the main factor driving the enhanced dry down rate. Similar trends were observed on using surface concentration as the purge metric. Hybrid purge schemes involving a combination of SSP and PCP were found to yield higher benefit in terms of efficient use of purge gas. Removal of strongly interacting contaminant species showed a higher benefit from use of controlled PCP scheme. Although, parametric analysis carried out on the operating factors of cyclic purge suggested that the enhancement in dry down increased with higher pressure range, it was highly conditional towards configurational factors in design and operation such as system dimensions, holding time, cycling pattern, valve loss coefficients and the complex inter coupling between them. The robustness of the process simulator allows the development of optimal purge scenarios for a given set of system parameters in order to perform a controlled purge. The benefit of using a hybrid PCP scheme was evaluated in terms of UHP purge gas and process time as a function of purity baseline required. Apart from UHP gas distribution systems, process vessels, chambers and components along the process stream are also prone to molecular contamination and pose a threat to product integrity. The dead volumes acting as areas of contaminant accumulation represent cavities or dead spaces in flow control elements such as mass flow controllers (MFCs), gauges, valves or dead spaces in process chambers. Steady purge has very little effect in cleanup of such areas and more efficient methods are necessitated to raise purge efficiency. The analysis of application of PCP is extended to such components through the development of a robust and comprehensive process simulator. The computational model applies a three dimensional physical model to analyze purge scenarios with steady and cyclic purge. The results presented pertain to any generic gas phase contaminant and electronic grade steel surfaces. Close investigation of the purge process helped elaborate the cleaning mechanism. Critical steps driving the purge process were identified as - dilution of chamber by introduction of fresh gas during re-pressurization and chamber venting during depressurization. Surface and gas phase purging of chambers with dead spaces using steady and cyclic purge were studied and compared. Cyclic purge exhibited a higher rate of dry down. The effect of system, design and purge operating parameters on surface cleaning were studied. Although higher frequency cycles and larger operating pressure ranges optimized for a given geometry are found to deliver better pressure cyclic purge (PCP) performances, the benefit is found to be contingent to a strong interplay between system parameters. PCP is found to be advantageous than steady state purge (SSP) in terms of purge gas usage and operation time in reaching a certain purity baseline. Specialty process gases supplied to the fabrication facility are typically stored in the form of liquids in enormous tanks outside the fab. Ammonia is a widely used in UHP concentrations for a variety of process including epitaxial growth, MOCVD, etching and wet processes in the semiconductor industry. The recent development in LED research has risen the demand and supply for Ammonia based compounds. Stringent baselines are maintained for the impurities associated with the manufacturing of such gases (e.g. Moisture in Ammonia). Apart from the difference in the rates of evaporation of the individual species from the storage cylinder causing accumulation of slower evaporating species, external temperature fluctuations also generate unsteady flux of desired species. When concentrations rise above this threshold additional purification or in most cases discarding large volumes of unused gas is warranted, causing loss of resources and causing ESH issues. Bulk gases are usually delivered over long lengths of large diameter pipes which produce large density of adsorption sites for contaminants to accumulate and eventually release into the gas stream. In order to establish contamination control in the gas delivery system, the surface interactions of the multispecies system with the delivery line surface was characterized. Desired concentrations of moisture in ammonia and UHP nitrogen mixtures were produced in a gas mixing section capable of delivering controlled mass flow rates to an EPSS test bed. Transient moisture profiles during adsorption and desorption tests at various test bed temperatures, mass flow rates and moisture concentration were captured by a highly sensitive analyzer. A mathematical model for single and multi-species adsorption was used in conjunction with experimental data to determinate kinetics parameters for moisture, ammonia system in EPSS surface. The results indicate competitive site binding on EPSS between ammonia and water molecules. Also, the concentration distribution of each species between surface, gas phase is interdependent and in accordance to the kinetic parameters evaluated. Back diffusion of impurity is a major source of contaminant introduction into UHP streams. Back diffusion refers to the transport of contaminants against the flow of bulk process stream. Molecular species can back diffuse from dead volumes, during mixing operations etc., simply when there is a gradient of concentration. A steady state approach was used to analyze the mechanism and effects of various geometrical and operational parameters on back diffusion. High sensitivity moisture detectors were used to capture the dynamics of contamination in a section of a generic distribution system. Results showed that back diffusion can occur through VCR fittings, joints and valves under constant purge. General trends on the effect of design parameters on back diffusion were derived from studies on various orifice sizes, system dimensions, flow rates and test moisture concentrations. Coupled parametric studies helped identify critical variable groups to perform dimensionless analysis on back diffusion of moisture. Crucial points where back diffusion can be minimized or completely eliminated are identified to help set up guidelines for cyclic and steady purge parameters without excessive use of expensive UHP gas or installation of unnecessarily large factors of safety. Wet cleaning of micro/nano sized features is a highly frequent process step in the semiconductor industry. The operation is a huge consumer of ultra-pure water and one of the main areas where process time minimization is focused. Comprehensive process model is developed to simulate the mechanism and capture the dynamics of rinsing high aspect ratio Silicon features in the nanometer scale. Rinsing of model trench, post etch contaminated with ammonium residue is studied. Mass transport mechanisms such as convection, diffusion are coupled with surface processes like adsorption and desorption. The effect of charged species on the trench surface and in the bulk, the resultant induced electric field on the rinse dynamics and decay of surface species concentration is studied. General rinsing trends and critical points in change in mechanisms were identified with critical groups such as mass transfer coefficient and desorption coefficient. The model is useful in evaluating process efficiency in terms of rinse time and DI water consumption under varying process temperature, contaminant concentration, and rinse fluid flow rate. The generic build of the model allows extension of its functionality to other impurity-substrate material couples.

Les interactions entre les flammes et les phénomènes thermiques sont le fil conducteur de ce travail. En effet, les flammes produisent de la chaleur, mais peuvent aussi être affectées par des transferts ou des sources de chaleur. La Simulation aux Grandes Echelles (SGE) est utilisée ici pour étudier ces interactions, en mettant l’accent sur deux sujets principaux: le transfert de chaleur aux parois et le contrôle de la combustion. Dans un premier temps, on étudie le transfert de chaleur aux parois dans un modèle de brûleur CH4/O2 de moteur-fusée. Dans un contexte deréutilisabilité et de réduction des coûts des lanceurs, qui constituent des enjeux majeurs, de nouveaux couples de propergols sont envisagés et les flux thermiques à la paroi doivent êtreprécisément prédits. Le but de ce travail est d’évaluer les besoins et les performances des SGEpour simuler ce type de configuration et de proposer une méthodologie de calcul permettant desimuler différentes configurations. Les résultats numériques sont comparés aux donnéesexpérimentales fournies par la Technische Universität München (Allemagne). Dans un deuxième temps, le contrôle de la combustion au moyen de décharges de plasma de type NRP (en anglaisNanosecond Repetitively Pulsed) est étudié. Les systèmes de turbines à gaz modernes utilisent en effet une combustion pauvre dans le but de réduire la consommation de carburant et les émissions de polluants. Les flammes pauvres sont connues pour être sujettes à des instabilités et le contrôle de la combustion peut jouer un rôle majeur dans ce domaine. Un modèle phénoménologique qui considère les décharges de plasma comme une source de chaleur est développé et appliqué à un brûleur pauvre avec prémélange CH4/Air stabilisé par un swirler. LesSGE sont réalisées afin d’évaluer les effets des décharges NRP sur la flamme. Les résultats numériques sont comparés aux observations expérimentales faites à la King Abdulla University ofScience and Technology (Arabie Saoudite)
Interactions between flames and thermal phenomena are the guiding thread of this work. Flamesproduce heat indeed, but can also be affected by it. Large Eddy Simulations (LES) are used hereto investigate these interactions, with a focus on two main topics: wall heat transfer andcombustion control. In a first part, wall heat transfer in a rocket engine sub-scale CH4/O2 burner isstudied. In the context of launchers re-usability and cost reduction, which are major challenges,new propellant combinations are considered and wall heat fluxes have to be precisely predicted.The aim of this work is to evaluate LES needs and performances to simulate this kind ofconfiguration and provide a computational methodology permitting to simulate variousconfigurations. Numerical results are compared to experimental data provided by the TechnischeUniversität München (Germany). In a second part, combustion control by means of NanosecondRepetitively Pulsed (NRP) plasma discharges is studied. Modern gas turbine systems use indeedlean combustion with the aim of reducing fuel consumption and pollutant emissions. Lean flamesare however known to be prone to instabilities and combustion control can play a major role in thisdomain. A phenomenological model which considers the plasma discharges as a heat source isdeveloped and applied to a swirl-stabilized CH4/Air premixed lean burner. LES are performed inorder to evaluate the effects of the NRP discharges on the flame. Numerical results are comparedwith experimental observations made at the King Abdulla University of Science and Technology(Saudi Arabia)

The education of health professionals is based on a series of discourses of professionalism that privilege notions of control and choice (Riggs, 2004a; Titchen and Higgs, 2001). These discourses are expressed through both explicit and implicit curricula, which encourage the enactment of a particular construction of the 'self' of both health professionals and clients or patients. This thesis adopts a feminist poststructural analysis of relations of power to explore some of the effects of the enactment of these curricula, drawing on three case studies of education in rural health settings and interviews with 17 health workers. The results indicate that the enactment of these curricula seems to produce a particular sense of self for health workers – one that is bound up with notions of control and choice, and one that may require struggle on an inner level with the self-regulation and self-policing (O'Grady, 2005) required to fit this norm. The struggle for female health workers to link the abstract theorizing with the actualities of their lives (Williams, 2002) seems to produce a paradoxical type of relationship with themselves and their clients. On one hand there is a discourse of conformity, compliance and obedience, which suggests more of a slippage of self while at the same time the expert-novice relationship characterizing the health professionals‟ interaction with clients emphasizes autonomy, control and empowerment of self. Further, while health workers see themselves as having high levels of internal locus of control this is in direct contrast to the helplessness and powerlessness they experience at work, and revealed through the research. The curriculum reform taking place within all health professional education at the moment emphasizes evidence-based practice and scientific content, and thus reinforces the dominant norm of the neo-liberal individual capable of self-regulation and self-policing. This research suggests the limitations of this approach, given the practices of power that continue to disadvantage women in general and patients in particular in relation to their health and the institution.

A avaliação da flexibilidade dos músculos da cadeia posterior é uma abordagem comum na prática clínica. O teste do terceiro dedo ao solo (DS) é frequentemente utilizado por ser de fácil aplicação e por ter se mostrado confiável e reprodutivo. O resultado do teste é a distância entre o terceiro dedo da mão e o solo e reflete a amplitude máxima permitida por esta cadeia muscular. Porém, o movimento para a execução do teste desloca para frente e para baixo grande parte da massa corporal exigindo respostas posturais para se evitar um risco de queda à frente. Foi levantada a hipótese de que o resultado desse teste possa variar de acordo com a demanda de equilíbrio do teste e a habilidade do indivíduo em realizar tais ajustes de equilíbrio. Objetivo: Verificar a influência do equilíbrio postural na flexibilidade mensurada pelo teste DS avaliada através de três paradigmas com os seguintes objetivos específicos: 1) verificar se a minimização da demanda de equilíbrio postural influencia o resultado do teste; 2) verificar se condições de aclive ou declive, que alteram as demandas de equilíbrio, influenciam no resultado do teste DS e; 3) verificar se é possível, através de uma rápida abordagem, orientar o indivíduo a executar uma estratégia de equilíbrio que melhore seu desempenho no teste DS. Métodos: 20 voluntários adultos jovens (6 homens e 14 mulheres) foram avaliados sobre uma plataforma de força em postura bípede quieta e em 6 testes DS em diferentes condições de demandas de equilíbrio na seguinte ordem: 1) Teste padrão (TP); 2) teste com suporte de equilíbrio (TS); 3) re-teste da condição padrão (re-teste); 4) teste em aclive (TAc); 5) teste em declive (TDc) 6) teste com orientações prévias de equilíbrio (TOr). Em cada um destes testes além da medida a distância entre o 3o dedo ao solo, foi calculada a posição média do Centro de Pressão (CP) através dos dados da plataforma de força e os ângulos articulares do tornozelo, joelho, quadril, lombar e tronco através de imagens digitais do voluntário em perfil. O ângulo de flexão total com a somatória dos ângulos também foi calculado. No paradigma 1 as variáveis foram comparadas entre condições TP, TS e re-teste. No paradigma 2 foram comparadas as condições TP, TAc e TDc. No paradigma 3 foram comparadas as condições TP e TOr. Os paradigmas 1 e 2 utilizaram a ANOVA para medidas repetidas com nível de significância p < 0,05 e teste post-hoc t de Student com correção de Bonferroni. Adicionalmente, no paradigma 1 foi realizado o teste de correlação de Pearson entre o resultado do teste DS e o CP. No paradigma 3 foi utilizado o teste T de Student com nível de significância p < 0,05. Resultados: O paradigma 1 mostrou melhora de 73% no resultado do teste DS, deslocamento anterior do CP, além de maior flexão de tornozelo e tronco na condição TS em relação ao TP. O ângulo de flexão total foi 30º maior na condição TS. O re-teste mostrou sinais de aprendizagem com resultados intermediários entre o TP e o TS. O CP correlacionou-se negativamente com o resultado do teste DS. O paradigma 2 mostrou grande melhora no resultado do teste DS em TAc em comparação a TDc e TP com maior flexão de tornozelo e maior flexão na soma das articulações. O paradigma 3 mostrou melhora de 62% no resultado do teste DS com deslocamento anterior do CP e maior flexão de tornozelo, lombar, tronco e soma dos ângulos em TOr em comparação com TP. Conclusão: O teste DS mostrou grande influência do equilíbrio postural. Condições com menor demanda de equilíbrio apresentaram resultados melhores que a condição com maior demanda. Na condição padrão de teste, o resultado foi melhor nas estratégias em que o CP é deslocado à frente. A instrução para que os indivíduos adotassem esta estratégia de equilíbrio levou a melhores resultados
Flexibility evaluation is a standard assessment in clinical and in sports settings. The Toe-touch test (TTT) is a common assessment tool to evaluate posterior muscular chain flexibility. It is a simple, reliable and reproductive test. But the test procedure implies a balance demand as it requires a great amount of body mass to be forward displaced. It was then hypothesized that the balance demand during the TTT and the subject\'s ability to deal with it may affect the flexibility measured by the test. Objective: The main objective was to verify the influence of postural balance on the flexibility measured by the TTT by means of three experimental paradigms with the following specific purposes: 1) to verify whether the minimization of the balance demand during the test may improve test results; 2) to verify whether the test outcome might be influenced by ground inclination (toes up or toes down); and 3) To verify if it is possible to briefly guide the subject to perform a better balance strategy to deal with the balance demand of the test. Methods: 20 young adults (6 men and 14 women) volunteered to participate. They were evaluated over a force platform during quiet stance and during 6 trials of the TTT under the following balance conditions: 1) Standard balance condition TTT (ST); 2) TTT with a balance support device (SupT); 3) ST re-test; 4) TTT over an inclined surface with toes up (TUT); 5) TTT over an inclined surface with toes down (TDT); 6) TTT with balance instructions (InsT). For each test it was calculated the mean position of the Center of Pressure (CP), the ankle, knee, hip, lumbar and trunk angles, as well as the sum of all these angles and the TTT outcome, i.e., the distance from the third finger to the ground. In the first experimental paradigm these variables were compared between tests ST, SupT and re-test. In the second paradigm the comparisons were performed between tests ST, TUT and TDT. And, finally, tests ST and InsT were compared in the third paradigm. In paradigms 1 and 2 the repeated measure ANOVA was performed with significance level of p < 0.05 and T student tests with Bonferroni correction as post-hoc tests. Additionally, the Pearson correlation test was used to calculate the correlation between CP and the tests outcomes. For the third paradigm it was used the T student test with significance level p < 0.05. Results: The first paradigm showed an average improvement of 73% in the test outcome associated by a forward CP displacement and greater ankle and trunk flexion in SupT compared to ST. The SupT also showed a greater flexion of 30? in the sum of angles. Re-test of ST showed learning effects with intermediary results between ST and SupT. Additionally, it was found a negative correlation between CP position and test outcome, the forward the CP, the better the test result. The second paradigm showed a great test improvement in TUT with greater flexion in ankle and in the summed angles compared to TDT and ST. And paradigm 3 showed an improvement of 62% in test outcome associated with forward CP displacement and greater ankle, lumbar, trunk and summed angles in InsT compared to ST. Conclusions: The TTT is highly influenced by balance. Test outcome was improved under less demanding conditions than those with more demanding condition. In the standard balance condition, test outcome was better when the balance strategy involved the forward displacement of the CP. The instruction to the subject to adopt that balance strategy lead to better test outcome

Human papillomavirus infection is the cause of more than 99% of cervical cancer cases. The current vaccine is ineffective therapeutically; highlighting the need for continued papillomavirus research. One avenue that could be explored in this regard is the function of the papillomavirus E2 regulatory proteins. HPV E2 represses expression of the viral E6 and E7 oncoproteins. Reintroduction of E2 into cervical carcinoma cells results in growth arrest and cellular senescence. Understanding the mechanism of how E2 regulates the early promoter may be key to developing new therapeutic and prophylactic vaccines. Here, we describe regulation of E2 through acetylation and possibly through direct interaction with a novel cellular interacting protein, RINT1. Histone acetyltransferase (HAT) proteins have been demonstrated to interact with Bovine Papillomavirus (BPV) and Human Papillomavirus (HPV) E2 proteins as well as enhance E2 dependant transcription luciferase reporter plasmid containing E2 binding sites. We demonstrate that HATs p300, CBP, and pCAF are limiting for E2 dependant transcriptional activation and that each protein functions independently. We have also identified that BPV-1 E2 is a substrate for acetylation by p300. Mutants of E2 that cannot be acetylated on lysines 111 or 112, display abnormal transcriptional phenotypes. Cells deficient in p300 display similar transcriptional defects that are intensified by CBP depletion. We propose that acetylation of BPV-1 E2 is necessary for transcriptional activation. Acetylation generates a binding site through which a co-factor may interact via a bromodomain. Regulation of E2 dependent transcriptional activation through a post-transcriptional modification represents a novel method through which BPV-1 controls gene expression. We also present evidence for a direct interaction between BPV-1 E2 and the cellular factor RINT1. This interaction does not appear to be critical for transcriptional regulation; however, several other functional pathways are indicated by the cellular complexes in which RINT1 functions. Some of these, such as ER/Golgi vesicular transport and hTERT independent telomere maintenance, are pathways in which E2 has no known role. Further investigation into regulation and consequences of E2 acetylation and the biological significance of the interaction between E2 and RINT1 could prove important in understanding the complex role of E2 in papillomavirus infection.

Dans cette thèse, une méthodologie simple pour trouver des bandes interdites robustes est présentée. Quatre cellules unitaires différentes sont utilisées comme exemples numériques pour des modèles infinis et finis. Les deux premiers sont liés aux zones d'atténuation créées pour les ondes longitudinales en utilisant des cellules unitaires de masse et ressort et de barres. La méthode Matrice de Transfert est utilisée pour modéliser la cellule unitaire. Avec cette méthode, il est possible d'obtenir les réponses en fréquence, en utilisant une méthode spectrale, et des constantes de dispersion, en résolvant un problème a valeur propre. Les paramètres physiques et géométriques les plus influents sont déterminés en effectuant une analyse de sensibilité aux dérivées partielles et aux différences finies à travers un modèle infini. Dans ce cas, pour le deuxième exemple, la section de la demi-cellule est considérée comme une variable stochastique, représentée par une fonction densité de probabilité pour une analyse probabiliste. Le troisième exemple concerne les bandes interdites pour les ondes de flexion utilisant des cellules unitaires de poutres. Dans ce cas, la méthode habituelle de Matrice de Transfert ne peut pas être utilisée pour obtenir une réponse de structures finies en basse fréquence en raison de la présence de matrices mal conditionnées. Par conséquent, une méthode récursive est utilisée pour éviter la multiplication de matrices. Une analyse expérimentale est également réalisée pour ce cas, mais considérant que la longueur de la moitié des cellules unitaire comme incertaine. Le dernier exemple est un treillis périodique considérée avec et sans propriétés intelligentes. La cellule unitaire de cette structure en treillis peut avoir des membres passifs et actifs. À cause de la complexité de ce type de cellule, la méthode des éléments finis est utilisée. Cependant, ce type de structure ne présente pas de ruptures d'impédance suffisamment fortes pour ouvrir des bandes interdites même avec la présence de sous-structures répétitives. En vertu de cela, huit scénarios sont étudiés en considérant l'introduction de masse concentrée dans les articulations et les actionneurs piézoélectriques dans les circuits shunt résonants qui sont considérés comme stochastiques pour des cas spécifiques. À la fin, les résonances internes sont analysées à l'aide d'un modèle plus précis. Pour chaque modèle de structure, une simulation de Monte Carlo avec Latin Hypercube est effectuée, les distinctions entre les zones d'atténuation incertaines correspondantes pour les modèles finis et infinis sont exposées et la relation avec les modes localisés est clarifiée. Ces résultats suggèrent que les modèles finis ont une bande interdite plus large que les modèles infinis en considérant les incertitudes. En d'autres termes, les incertitudes entre les cellules voisines se compensent et les structures finies sont naturellement plus robustes. Enfin, l'effet de l'augmentation du niveau d'incertitude, en faisant varier un coefficient stochastique, est analysé et le concept de bande interdite robuste est présenté
In this thesis, a simple methodology to find robust bandgaps is presented. Four different periodic structures are used as numerical examples for infinite and finite models. The first two are related to attenuation zones created for longitudinal waves using spring-mass and stepped rod unit cells. The Transfer Matrix method is used to model the unit cell. With this method, it is possible to obtain the frequency responses, using a spectral method, and dispersion constants, solving an eigenvalue prob-lem. The most influential physical and geometrical parameters are determined by performing partial derivative and finite difference sensitivity analysis through an infinite model. Therein, for the second example, the cross-section area of half-cell is considered as a stochastic variable represented by a probability density function with specific deviation properties for a probabilistic analysis. The third example concerns the bandgaps for flexural waves using stepped beams unit cells. For this case, the classical Transfer Matrix method cannot be used to obtain finite structures response in low frequency because of the presence of ill-conditioned matrices. Therefore, a recursive method termed Translation Matrix, which avoid matrix multiplication, is used and the corresponding probabilistic analysis is per-formed using the half-cell thickness as a random variable. An experimental analysis is also performed for this case, but considering half-cell length as uncertain. The last example is a periodic truss that is considered with and without smart components. The unit cell of this lattice structure can present pas-sive and active members. As long as the type of unit cell is more complex, the finite element method is used. However, this kind of structure does not have impedance mismatches strong enough to open bandgaps although the presence of repetitive substructures. In virtue of this, eight scenarios are inves-tigated considering the introduction of concentrated mass on joints and piezoelectric actuators in reso-nant shunt circuit which are considered as stochastic for specific cases. For each structure model, a Monte Carlo Simulation with Latin Hypercube sampling is carried out, the distinctions between the corresponding uncertain attenuation zones for finite and infinite models are exposed and the relation with localized modes is clarified. These results lead to conclude that the finite models present a larger stop zone considering stochastic parameters than infinite models. In other words, the uncertainties be-tween neighbors’ cells compensate each other and the finite structures is naturally more robust. Final-ly, the effect of increasing the uncertainty level, by varying a stochastic coefficient, is analyzed and the concept of robust band gap is presented

Transcriptional regulation of cell cycle controlled genes is fundamental to cell division in eukaryotes and a broad spectrum of physiological processes directly related to cell proliferation. Expression of the cell cycle dependent human H4, H3 and H1 histone genes is coordinately regulated at both the transcriptional and posttranscriptional levels. We have systematically analyzed the protein/DNA interactions of the immediate 5'regions of three prototypical cell cycle controlled histone genes, designated H4-F0108, H3-ST519 and H1-FNC16, to define components of the cellular mechanisms mediating transcriptional regulation. Multiple biochemically distinct protein/DNA interactions were characterized for each of these genes, and the binding sites of several promoter-specific nuclear DNA binding activities were delineated at single nucleotide resolution using a variety of techniques. These findings were integrated with results obtained by others and revealed that the in vitro factor binding sites in H4, H3 and H1 histone promoters coincide with genomic protein/DNA interaction sites defined in vivofor the H4-F0108 and H3-STS19 genes, and with evolutionarily conserved cis-acting sequences shown to affect the efficiency of histone gene transcription. Specifically, we have defined binding sites for Sp1, ATF, CP1/NF-Y, HiNF-D, HiNF-M, HiNF-P and HMG-I related factors. Based on sequence-similarities and cross-competition experiments, we postulate that most of these protein/DNA interaction elements are associated with more than one class of histone genes. Thus, the protein/DNA interactions characterized in this study may represent components of a cellular mechanism that couples transcription rates of the various histone gene classes. Regulation of the protein/DNA interactions involved in transcriptional control of these H4, H3 and H1 histone genes was investigated in a spectrum of cell types using several distinct in vitro cell culture models for the onset of differentiation and quiescence, as well as cell cycle progression. Moreover, we studied control of histone gene associated DNA binding activities during hepatic development from fetus to adult in transgenic mice reflecting the onset of differentiation and quiescence in vivo. We show that the H4 histone promoter protein/DNA interaction mediated by factor HiNF-D is selectivelymodulated, and directly at the level of DNA binding activity, during the entry into, progress through and exit from the cell cycle in normal diploid cells, as well as during hepatic development. The regulation of this protein/DNA interaction occurs in parallel with analogous interactions occurring in H3 and H1 histone genes. Moreover, these proliferation-specific protein/DNA interactions are collectively deregulated during the cell cycle in four distinct cell types displaying properties of the transformed phenotype. Hence, the cellular competency to coordinately transcribe distinct classes of histone genes during the cell cycle may be mediated by the intricate interplay of constitutively expressed general transcription factors and temporally regulated, cell growth controlled nuclear factors interacting specifically with cell cycle dependent histone genes. Finally, we show that HiNF-D is represented by two electrophoretically distinct species. The ratio of these forms of HiNF-D fluctuates dramatically during the cell cycle of normal diploid cells, but remains relatively constant in tumor cells. Total HiNF-D binding activity embodied by both HiNF-D species is negatively influenced in vitro by incubation with exogenous phosphatase activity. These observations provide a first indication for the hypothesis that HiNF-D may exist in distinct post-translationally modified forms that are subject to a stringent cell growth control mechanism involving protein kinases and phosphatases. Such a cellular post-translational modification mechanism, which directly impinges on (or activates) the DNA binding activity of a key factor controlling histone genes, would provide a highly efficient means by which to influence the rate of transcription in rapid response to intra-cellular requirements for histone mRNA and extra-cellular cues signalling the onset and cessation of cell proliferation.

The proper maintenance of the pathways governing cell growth is critical to ensure cell survival and DNA fidelity. Much of our understanding of how the cell cycle is regulated comes from studies examining the relationship between DNA viruses and the mechanisms of cell proliferation control. There are numerous examples demonstrating that viruses can alter the host cell environment to their advantage. In particular, the small DNA tumor viruses, which include adenovirus, simian-virus 40 (SV-40), and human papillomavirus (HPV), can modulate the host cell cycle to facilitate viral DNA replication. Due to the fact that these viruses infect quiescent, non-cycling cells and lack the necessary enzymes and resources to replicate their DNA (e.g. DNA polymerase), the small DNA tumor viruses must activate the host cell replication machinery in order to expedite viral DNA replication. The capacity of these viruses to perturb normal cell proliferation control is dependent upon their oncogene products, which target p53 and members of the Retinoblastoma (RB) family of proteins and inactivate their respective functions. By targeting these key cell cycle regulatory proteins, the small DNA tumor viruses induce the infected host cells to enter S-phase and activate the components involved with host cell DNA synthesis thereby generating an environment that is conducive to viral DNA replication. In contrast, the larger, nuclear-replicating DNA viruses such as those from the family Herpesviridae, do not share the same stringent requirement as the small DNA viruses to induce the infected host cell to enter S-phase. The herpesviruses encode many of the components to stimulate nucleotide biosynthesis and the necessary factors to facilitate virus DNA replication including a viral DNA polymerase and other accessory factors. Additionally, many herpesviruses encode gene products that arrest the host cell cycle, in most instances, prior to the G1/S transition point. Inducing cells to growth arrest appears to be a prerequisite for the replication of most herpesviruses. However, in addition to encoding factors that inhibit the cell cycle, many herpesviruses encode proteins that can promote cell cycle progression in a manner similar to the small DNA tumor virus oncoproteins. By targeting members of the RB family and p53 protein, the herpesvirus proteins induce S-phase and activate S-phase associated factors that playa role in DNA replication. In this manner, the herpesviruses may promote an environment that is favorable for DNA replication. Consistent with the other herpesviruses, human cytomegalovirus (HCMV)induces human fibroblasts to growth arrest. However, in other cell types, virus infection causes cells to enter S-phase. In addition, HCMV replication requires several cellular factors that are present only during S-phase. Furthermore, HCMV induces the activation of S-phase-associated events as well as the increased expression of numerous S-phase genes following infection. HCMV encodes two immediate early (IE) gene products, IE1-72 and IE2-86, which can interact with members of the RB family of proteins. Additionally, the IE2-86 protein can bind to and inhibit p53 protein function. Given the functional resemblance between the HCMV IE proteins and the oncoproteins of the small DNA tumor viruses, we hypothesized that expression of the HCMV IE proteins could modulate cell cycle control. Specifically, we determined that expression of either IE1-72 or IE2-86 can induce quiescent cells to enter S-phase and delay cell cycle exit following serum withdrawal. Moreover, IE2-86 mediates this effect in the presence or absence of p53, whereas IE1-72 fails to do so in p53-expressing cells. Furthermore, both IE1-72 and IE2-86 induce p53 protein accumulation that is nuclear localized. Because IE1-72 fails to promote S-phase entry in cells expressing p53 and induces p53 protein levels, the mechanism by which IE1-72 alters p53 levels was examined. IE1-72 elevates p53 protein levels by inducing both p19ARF protein and an ATM-dependent phosphorylation of p53 at Ser15. IE1-72 also promotes p53 nuclear accumulation by abrogating p53 nuclear shuttling. As consequence of this IE1-72-mediated increase in p53 levels, p21 protein is induced leading to a p21-dependent growth arrest in cells expressing IE1-72. These findings demonstrate that the HCMV IE proteins can alter cell proliferation control and provide further support to the notion that HCMV, through the expression of its IE proteins, induces S-phase and factors associated with S-phase while blocking cell DNA synthesis, to possibly generate an environment that is suitable for viral DNA replication.

Room models, currently used for controller tests, assume the room air to be perfectly mixed. A new room model is developed, assuming non-homogeneous room conditions and distinguishing between different sensor positions. From measurement in real test rooms and detailed CFD simulations, a list of convective phenomena is obtained that has to be considered in the development of a model for a room equipped with different HVAC systems. The zonal modelling approach that divides the room air into several sub-volumes is chosen, since it is able to represent the important convective phenomena imposed on the HVAC system. The convective room model is divided into two parts: a zonal model, representing the air at the occupant zone and a second model, providing the conditions at typical sensor positions. Using this approach, the comfort conditions at the occupant zone can be evaluated as well as the impact of different sensor positions. The model is validated for a test room equipped with different HVAC systems. Sensitivity analysis is carried out on the main parameters of the model. Performance assessment and energy consumption are then compared for different sensor positions in a room equipped with different HVAC systems. The results are also compared with those obtained when a well-mixed model is used. A main conclusion of these tests is, that the differences obtained, when changing the position of the controller's sensor, is a function of the HVAC system and controller type. The differences are generally small in terms of thermal comfort but significant in terms of overall energy consumption. For different HVAC systems the cases are listed, in which the use of a simplified model is not recommended. This PhD has been submitted in accordance to the conditions for attaining both the French and the German degree of a PhD, on a co-national basis, in the frame of a statement of the French government from January 18th, 1994. The research has been carried out in the Automation and Energy Management Group (AGE), Department of Sustainable Development (DDD), at the &quot;Centre Scientifique et Technique du Bâtiment&quot; (CSTB) in Marne la Vallée, France, in collaboration with the &quot;Centre Energétique&quot; (CENERG) at the &quot;Ecole Nationale Supérieure des Mines de Paris&quot; (ENSMP), Paris, France and the Technical University of Dresden (TUD), Germany.

Froth flotation is the most commonly used process to recover and upgrade the portion of the coal preparation plant feed that has a particle size smaller than 150 microns. Problems that occur when employing froth flotation in the coal industry include i) coal surfaces that are weakly-to-moderately hydrophobic, and ii) flotation systems that are overloaded and limited by insufficient retention time. Research was performed to evaluate techniques that could be implemented to improve flotation performance under the aforementioned scenarios. Pre-aeration of flotation feed using a cavitation system was extensively evaluated in laboratory and full-scale test programs. The benefits of adding hydrophobic, magnetic plastic particles were also investigated to improve froth stability and increase bubble surface area. Laboratory tests revealed that pre-aeration through a cavitation tube improved coal recovery by as much as 20 absolute percentage points in both conventional cells and flotation columns when treating difficult-to-float coals. Carrying capacity increased by 32% which was projected to provide a 4 t/h increase in flotation recovery for a typical 4-m diameter flotation column. Product size analyses suggest that the improved particle recovery was more pronounced for the finest coal fractions as a result of particle agglomeration, resulting from the use of the nucleated air bubbles on the coal surfaces as a bridging medium. In-plant testing of a commercial-scale cavitation system found that feed pre-aeration could reduce collector dosage by 50% when no additional air is added and by 67% when a small amount of air is added to the feed to the cavitation system. At a constant collector dosage, recovery increased by 10 absolute percentage points with cavitation without additional air and 17 absolute points when additional air is provided. The addition of hydrophobic plastic particles to the flotation feed at a 10% concentration by weight was found to substantially improve froth stability thereby elevating the recovery and enhancing carrying-capacity. Test results showed that the primary flotation improvements were directly linked to the coarsest particle size fractions in the plastic material which supports the froth stability hypothesis. Combustible recovery was increased up to 10 percentage points while producing the desired concentrate quality.

T lymphocytes are distinguished by the expression of αβ TCR or γδ TCR on their cell surface. The kinetic differences in the effector functions classifies γδ T cells as innate-like lymphocytes and αβ T cells as adaptive lymphocytes. Although distinct, αβ and γδ T cell lineages produce a common array of cytokines to mount an effective immune response against a pathogen. The production of cytokine IL-17 is a shared characteristic between the γδ T (Tγδ17) cells and the CD4 T (Th17) cells. γδ T cells develop into Tγδ17 cells in the thymus whereas CD4 T cells differentiate into Th17 cells in response to antigens in the peripheral lymphoid tissues. γδ T cells exported from the thymus, as pre-made effectors, are the early IL-17 producers compared with the late IL-17 producing Th17 cells. In this thesis we describe how TGFβ-SMAD2 dependent pathway selectively regulates Th17 cell differentiation but not Tγδ17 cells generation. We further illustrate the requirement of WNT-HMG box transcription factor (TF) signaling for the thymic programming of Tγδ17 cells. Cytokine TGFβ in co-operation with IL-6 induces the differentiation of Th17 cells. Conversely, TGFβ signaling also regulates the differentiation and maintenance of CD4+FOXP3+ regulatory T cells. The mechanism by which TGFβ signals synergize with IL-6 to generate inflammatory versus immunosuppressive T cell subsets is unclear. TGFβ signaling activates receptor SMADs, SMAD2 and SMAD3, which associate with a variety of nuclear factors to regulate gene transcription. Defining relative contributions of distinct SMAD molecules for CD4 T cell differentiation is critical for mapping the versatile intracellular TGFβ signaling pathways that tailor TGFβ activities to the state of host interaction with pathogens. We show here that SMAD2 is essential for Th17 cell differentiation and that it acts in part by modulating the expression of IL-6R on T cells. While mice lacking SMAD2 specifically in T cells do not develop spontaneous lymphoproliferative autoimmunity, Smad2-/- T cells are impaired in their response to TGFβ in vitro and in vivo and they are more pathogenic than controls when transferred into lymphopenic mice. These results demonstrate that SMAD2 is essential for TGFβ signaling in CD4+ T effector cell differentiation and that it possesses functional capabilities distinct from SMAD3. Although SMAD2 is essential for the differentiation of Th17 cells, TGFβ signaling via SMAD2 is not required for the thymic programming of innate Tγδ17 cells. Among different γδ T cells, Vγ2+ (V2) γδ T cells are the major IL-17 producing subsets. We demonstrate that Sry-high mobility group (HMG) box TFs regulate the development of V2 Tγδ17 cells. We show that the HMG box TF, SOX13 functions in a positive loop for the intrathymic generation of V2 Tγδ17 cells. SOX13 regulates the programming of Tγδ17 cells by controlling the expression of B-lymphoid kinase (BLK) in developing immature V2 γδ T cells. BLK is an Src-family kinase expressed by all Tγδ17 cells. Furthermore, we show another HMG box TF, TCF1, the nuclear effector of canonical WNT signaling, is the primary negative regulator of IL-17 production by all γδ T cells. We propose that the antagonism of SOX13 and TCF1 determines the generation of IL-17 producing γδ T cells. We also show that extrinsic cues from αβ T cells do not affect the generation of IL-17 producing γδ T cells. Using OP9-DL1 culture system, we demonstrate that the progenitors of V2 Tγδ17 cells are the c-Kit+ early thymic precursors.

A continuous increase in demands from the utility grid and traction applications have steered public attention toward the integration of energy storage (ES) and hybrid ES (HESS) solutions. Modern technologies are no longer limited to batteries, but can include supercapacitors (SC) and flywheel electromechanical ES well. However, insufficient control and algorithms to monitor these devices can result in a wide range of operational issues. A modern day control platform must have a deep understanding of the source. In this dissertation, specialized modular Energy Storage Management Controllers (ESMC) were developed to interface with a variety of ES devices. The EMSC provides the capability to individually monitor and control a wide range of different ES, enabling the extraction of an ES module within a series array to charge or conduct maintenance, while remaining storage can still function to serve a demand. Enhancements and testing of the ESMC are explored in not only interfacing of multiple ES and HESS, but also as a platform to improve management algorithms. There is an imperative need to provide a bridge between the depth of the electrochemical physics of the battery and the power engineering sector, a feat which was accomplished over the course of this work. First, the ESMC was tested on a lead acid battery array to verify its capabilities. Next, physics-based models of lead acid and lithium ion batteries lead to the improvement of both online battery management and established multiple metrics to assess their lifetime, or state of health. Three unique HESS were then tested and evaluated for different applications and purposes. First, a hybrid battery and SC HESS was designed and tested for shipboard power systems. Next, a lithium ion battery and SC HESS was utilized for an electric vehicle application, with the goal to reduce cycling on the battery. Finally, a lead acid battery and flywheel ES HESS was analyzed for how the inclusion of a battery can provide a dramatic improvement in the power quality versus flywheel ES alone.

Mestrado em Engenharia Civil
The present dissertation aims to combine the use of Computational Fluid Dynamics (CFD) software, to support the design of ventilation systems in passive houses. Sustainable construction is an increasing concern in the current construction market, finding in these houses a valid alternative in order to enhance energy savings in this sector. A passive house is known for achieving high levels of thermal comfort without consuming too much energy. In addition to an extremely rigorous thermal insulation, the use of highly efficient ventilation systems is one of the main factors in achieving such levels of comfort. Therefore, this dissertation intends to study the circulation of air associated to the mechanical ventilation system of a passive house in Portugal and consequent analysis of its thermal comfort. To achieve such purpose, a CFD commercial program called FLOW-3D® will be used. It was necessary to perform a validation of the program by comparing air velocities obtained numerically by the program and experimentally through the registration of air velocities in the studied passive house with the use of digital anemometers. Lastly, after the validation described above, an analysis over the thermal comfort of the building was performed, based on temperature registrations obtained experimentally and velocity values obtained from the numerical simulations.
A presente dissertação visa aliar o uso de programas de simulação numérica de fluidos, mais concretamente a mecânica dos fluidos computacional (CFD), no apoio à conceção de sistemas de ventilação em casas passivas. A construção sustentável é cada vez mais uma preocupação no mercado atual da construção, encontrando nessas casas uma alternativa muito válida no que toca a poupanças de energia neste setor. Uma casa passiva é reconhecida por obter altos níveis de conforto térmico sem necessidade de grandes consumos de energia. Para além de um isolamento térmico rigoroso, o uso de sistemas de ventilação de elevada eficiência é um dos principais fatores para atingir tais níveis de conforto. Esta dissertação pretende, por isso, fazer um estudo da circulação de ar resultante de um sistema de ventilação mecânica numa casa passiva construída em Portugal e a consequente análise do conforto térmico que nela se obtém, tendo sido utilizado um programa comercial de CFD, o FLOW-3D®. Foi necessário realizar uma validação do programa através da comparação de valores de velocidade do ar obtidos numericamente pelo respetivo algoritmo de cálculo e experimentalmente através do registo de velocidades do ar na casa passiva objeto de estudo, tendo-se utilizado para o efeito anemómetros digitais. Por fim, após a validação descrita anteriormente, foi feita uma análise do conforto térmico do edifício em estudo com base em registos de temperatura obtidos experimentalmente e de velocidades do ar obtidos da simulação efetuada.

Ces travaux portent sur la commande et l’analyse de la stabilité d’un système électropneumatique constitué d’un axe linéaire commandé par deux servodistributeurs régulant le débit massique entrant dans chaque chambre de l’actionneur. La problématique générale est motivée par l’apparition d’un phénomène de redécollage sur ce système électropneumatique difficilement pris en compte par les études actuelles en automatique. Ce problème, rencontré depuis de nombreuses années, concerne toutes les commandes linéaires et non linéaires mono et multidimensionnelles étudiées au laboratoire. Il se traduit par des mouvements saccadés du vérin au voisinage de l’équilibre. Ce phénomène est dû à la présence de frottements secs et aux dynamiques des pressions dans les chambres pneumatiques de l’actionneur, qui continuent à évoluer (intégrer le débit massique entrant délivré par les servodistributeurs), même après l’équilibre mécanique. La première partie de ce mémoire propose une commande non linéaire commutée afin d’éviter le phénomène de redécollage de l’actionneur électropneumatique notamment vis-à-vis des variations de frottements secs qui peuvent à tout moment causer ce phénomène. Cette technique est finalement mise en œuvre et son efficacité est constatée. La plus grande partie de ce mémoire traite l’analyse de l’actionneur électropneumatique avec sa loi de commande commutée. La présence de frottements secs et l’application d’une loi de commande commutée nous a amené à concilier une démarche d’analyse de stabilité, en considérant une classe de systèmes commutés appelée systèmes affines par morceaux. La principale difficulté de cette démarche réside dans l’obtention de fonctions de Lyapunov adéquates, qui se transforme en un problème d’optimisation sous contraintes LMI (Linear Matrix Inequality) en utilisant la S-procédure. Afin d’analyser la stabilité d’un système PWA (PieceWise Affine), la première démarche proposée permet le calcul d’une fonction de Lyapunov quadratique par morceaux sous la forme d’un problème d’optimisation sous contraintes LMI, en imposant des conditions suffisantes de stabilité. Ces dernières permettent, contrairement aux méthodes classiques, d’assurer la convergence de trajectoires d’état non pas vers un point d’équilibre, mais vers un ensemble des points d’équilibre d’un système PWA. L’approche proposée permet aussi l’étude de la robustesse vis-à-vis des variations paramétriques dans le système. Nous proposons aussi une deuxième approche pour la construction d’un type de fonctions de Lyapunov dites polynomiales par morceaux, via l’utilisation des "sum of square" et de la "power transformation", afin d’analyser la stabilité d’un ensemble de points d’équilibre d’un système PWA, en présence de phénomènes de glissement et de variations paramétriques. Cette approche propose des conditions suffisantes moins conservatives que celles imposées par les fonctions de Lyapunov quadratique par morceaux. En effet, sur des exemples de systèmes PWA présentant de dynamiques discontinues sur les frontières entre les cellules, pouvant générer à tout moment des phénomènes de glissement, ces dernières s’avèrent inefficaces et ne permettent pas d’assurer la stabilité des systèmes PWA en présence de ces phénomènes. Par conséquent, les résultats sur la fonction de Lyapunov quadratique par morceaux sont étendus pour pouvoir calculer des fonctions de Lyapunov polynomiales par morceaux d’ordre supérieur, en résolvant un problème d’optimisation sous contraintes LMI. Ces dernières permettent de garantir des conditions plus générales et moins conservatives par rapport à celles développées dans la littérature. Ces deux approches ont été appliquées afin d’analyser la stabilité de l’ensemble des points d’équilibre du système électropneumatique, en considérant à la fois un modèle de frottements sous la forme d’une saturation et un autre sous la forme d’un relais présentant une dynamique discontinue. [...]
This work focuses on the control and stability analysis of an electro-pneumatic system, i.e. a linear pneumatic cylinder controlled by two servo valves regulating the mass flow entering each chamber of the actuator. The general problem is motivated by the appearance of stick-slip on the electro-pneumatic system, hardly taken into account by the current studies in automatic control. This problem, encountered throughout the years, concerns all mono- and multidimensional linear and non-linear controls systems studied at the laboratory. In pneumatic cylinders, the phenomenon consists in a displacement of the rod a while after it has come to a rest ; this is due to the fact that the force acting on the rod initially becomes smaller that the threshold which is necessary for a motion, and then this threshold is overcome later on. In this case, stick-slip is caused by the presence of dry friction and by the pressure dynamics in the chambers, which continue to evolve (integrating the net incoming mass flow from the servovalves) even after the rod has stopped. The first part of this thesis proposes a nonlinear switching control law in order to avoid stick-slip on pneumatic cylinder, taking into account with the variations of dry friction that may occur at any time causing this phenomenon. This technique is implemented and its effectiveness is recognized. The greatest part of this thesis deals with the stability analysis of the pneumatic cylinder with its switched control law. The presence of dry friction and the application of a switched control law requires an appropriate method for approaching the stability analysis ; this method is based on considering the closed-loop system as belonging to a class of switched systems called piecewise affine systems (PWA). The main difficulty in this approach lies in obtaining adequate Lyapunov functions for proving stability, which turns into an optimization problem under LMI constraints (Linear Matrix Inequality) using the S-procedure. In order to analyze the stability of a PWA system, a first method is proposed allowing the computation of a piecewise quadratic Lyapunov function through an optimization problem under LMI constraints. The methods takes into account, in contrast to conventional methods, that the states might converge not to a single point but to a set of equilibrium points. The proposed approach allows also the study of robustness with respect to parametric variations in the system. A second method is also proposed for the construction of a type of Lyapunov functions called piecewise polynomial, using the “sum of squares” and “power transformation” techniques. This approach proposes less conservative sufficient conditions than those imposed by the piecewise quadratic Lyapunov functions, yielding a more succesfull stability test when for PWA systems featuring sliding modes and parametric variations. In fact, on PWA systems with discontinuous dynamics (which can generate sliding phenomena), piecewise quadratic Lyapunov functions might prove ineffective to prove the stability. Therefore, the results on piecewise quadratic Lyapunov functions are extended in order to compute piecewise polynomial Lyapunov functions of higher order, by solving an optimization problem under LMI constraints. These functions are more general and allow less conservative conditions compared to those formerly developed in the literature. Both of these methods have been applied to the stability analysis of the set of equilibrium points of the pneumatic cylinder, considering first a friction model in saturation form and then a model in relay form with a discontinuous dynamics. The application of the methods is successful, i.e. the robust stability is proven under dry friction threshold variations, with possibility of sliding modes

L'intelligence en essaim constitue désormais un domaine à part entière de l'intelligence artificielle distribuée. Les problématiques qu'elle soulève touchent cependant à de nombreux autres domaines ou questions scientifiques. En particulier le concept d'essaim trouve pleinement sa place au sein de la science dites des ``systèmes complexes''. Cette thèse présente ainsi la conception, les caractéristiques et les applications d'un modèle original, le SMA logistique, pour le domaine de l'intelligence en essaim. Le SMA logistique trouve son origine en modélisation des systèmes complexes : il est en effet issu des réseaux d'itérations couplées dont nous avons adapté le modèle de calcul à l'architecture multi-agent. Ce modèle se fonde sur des principes communs à d'autres disciplines, comme la synchronisation et le contrôle paramétrique que nous plaçons au coeur des mécanismes d'auto-organisation et d'adaptation. Du point de vue mathématique, les applications logistiques sont à la base de la formalisation du comportement interne des agents constituant le SMA logistique, tout en prenant place dans un schéma ``influence-réaction''. L'environnement à base de champs est l'autre aspect fondamental du SMA logistique, en permettant la réalisation des interactions indirectes des agents et en jouant le rôle d'une structure de données pour le système. Les travaux décrits dans cette thèse donnent lieu à des applications principalement en simulation et en optimisation, comme c'est le cas pour la plupart des algorithmes du domaine de l'intelligence en essaim. L'intérêt et l'originalité du SMA logistique pour l'intelligence en essaim résident dans l'aspect générique de son schéma théorique qui permet de traiter avec un même modèle des phénomènes considérés a priori comme distincts dans la littérature : phénomènes de ``flocking'' et phénomènes stigmergiques ``fourmis'' à base de phéromones. Ce modèle répond ainsi à un besoin d'explication des mécanismes mis en jeu autant qu'au besoin d'en synthétiser les algorithmes générateurs.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Heat stress is the imbalance that occurs in the animal organism in response to adverse weather conditions, triggering several metabolic disorders, physiological and productive animals. In order to control the physiological changes of the sheep to thermal stress, it was proposed to use appropriate levels of electrolyte and its appropriate proportion in the feed. Thus the present study aimed to evaluate the effect of changes in electrolyte balance of diets, based on changes in the balance sheet (BE) and electrolyte ratio (RE) as a way to control the physiological changes caused by thermal stress in sheep. Therefore, we considered the physiological parameters of 12 lanados lambs were assigned to a completely randomized experimental design, in incomplete factorial arrangement 3x3 with five diets, resulting from combinations of BE 0, 50 and 100 and RE 5: 1, 10: 1 to 15: 1. The physiological parameters were evaluated in three distinct periods, two with average temperatures of 28 ° C, with an intermediate period with temperatures ranging between 35 and 37 ° C. The results were submitted to analysis of variance and regression analysis later. The physiological parameters heart rates, respiratory, rectal mucosal temperature, eyeball, armpit and ruminal movements were sensitive to the supplementation levels of BE and RE. The results indicated that the groups with lower BE RE 50 and 8 to 14 were superior. Thus we conclude that the optimum use of electrolyte balance in sheep was able to modulate physiological responses of these animals mitigating the effects of heat stress

Resumo:O estresse térmico é o desequilíbrio que ocorre no organismo animal em resposta às condições climáticas adversas, desencadeando vários distúrbios metabólicos, fisiológicos e produtivos em animais. Com a finalidade de controlar as alterações fisiológicas dos ovinos ao estresse térmico, propôsse a utilização de níveis apropriados de eletrólitos e a sua adequada proporção na ração. Assim o presente trabalho objetivou avaliar o efeito de alterações no equilíbrio eletrolítico de dietas, com base em modificações no balanço (BE) e relação eletrolítica (RE), como forma de controle das alterações fisiológicas causada pelo estresse térmico em ovinos. Para tanto, foram considerados os parâmetros fisiológicos de 12 cordeiros lanados, distribuídos em um delineamento experimental inteiramente ao acaso, em arranjo fatorial incompleto 3x3, totalizando cinco tratamentos, decorrentes de combinações entre BE 0, 50 e 100 e RE 5:1, 10:1 e 15:1. Os parâmetros fisiológicos foram avaliados em três períodos distintos, dois deles com temperaturas médias de 28ºC, apresentando um período intermediário com temperaturas variando entre 35 e 37ºC. Os resultados foram submetidos à análise de variância e posteriormente a análise de regressão. Os parâmetros fisiológicos: frequências cardíaca, respiratória, temperatura de mucosa retal, do globo ocular, da axila e movimentos ruminais apresentaram-se sensíveis aos níveis de suplementação de BE e RE. Os resultados indicaram que os grupos com BE menores que 50 e RE entre 8 e 14 foram superiores. Dessa forma podemos concluir que a utilização do ideal equilíbrio eletrolítico em ovinos foi capaz de modular as respostas fisiológicas desses animais mitigando os efeitos do estresse térmico
Abstract:Heat stress is the imbalance that occurs in the animal organism in response to adverse weather conditions, triggering several metabolic disorders, physiological and productive animals. In order to control the physiological changes of the sheep to thermal stress, it was proposed to use appropriate levels of electrolyte and its appropriate proportion in the feed. Thus the present study aimed to evaluate the effect of changes in electrolyte balance of diets, based on changes in the balance sheet (BE) and electrolyte ratio (RE) as a way to control the physiological changes caused by thermal stress in sheep. Therefore, we considered the physiological parameters of 12 lanados lambs were assigned to a completely randomized experimental design, in incomplete factorial arrangement 3x3 with five diets, resulting from combinations of BE 0, 50 and 100 and RE 5: 1, 10: 1 to 15: 1. The physiological parameters were evaluated in three distinct periods, two with average temperatures of 28 ° C, with an intermediate period with temperatures ranging between 35 and 37 ° C. The results were submitted to analysis of variance and regression analysis later. The physiological parameters heart rates, respiratory, rectal mucosal temperature, eyeball, armpit and ruminal movements were sensitive to the supplementation levels of BE and RE. The results indicated that the groups with lower BE RE 50 and 8 to 14 were superior. Thus we conclude that the optimum use of electrolyte balance in sheep was able to modulate physiological responses of these animals mitigating the effects of heat stress
Orientador:Luiz Cláudio Nogueira Mendes
Banca:Sirlei Aparecida Maestá
Banca:Manoel Garcia Neto
Mestre

This thesis investigates advanced control methods and strategies to enhance the transient stability of a power system which is affected by the electromechanical wave propagation phenomenon. The characteristics of the travelling wave phenomenon and its impact on system separation during first swing are investigated in detail. This thesis identifies four innovative control implications for power system stability and proposes an improved method to enhance power system transient stability. By designing better control of existing equipment, this research achieves increased maximum power transfer under contingencies in a cost efficient and readily implemented way.

As equações do modelo bidimensional de veículos autônomos subaquáticos fornecem um exemplo de sistema de controle não linear com o qual podemos ilustrar propriedades da teoria de controle ótimo. Apresentamos, sistematicamente, como os conceitos de formalismo hamiltoniano e teoria de Lie aparecem de forma natural neste contexto. Para tanto, estudamos brevemente o Princípio do Máximo de Pontryagin e discutimos características de sistemas afins. Tratamos com cuidado do Fenômeno Fuller, fornecendo critérios para decidir quando ele está ou não presente em junções, utilizando para isso uma linguagem algébrica. Apresentamos uma abordagem numérica para tratar problemas de controle ótimo e finalizamos com a aplicação dos resultados ao modelo bidimensional de veículo autônomo subaquático.
The equations of the two-dimensional model for autonomous underwater vehicles provide an example of a nonlinear control system which illustrates properties of optimal control theory. We present, systematically, how the concepts of the Hamiltonian formalism and the Lie theory naturally appear in this context. For this purpose, we briefly study the Pontryagin\'s Maximum Principle and discuss features of affine systems. We treat carefully the Fuller Phenomenon, providing criteria to detect its presence at junctions with an algebraic notation. We present a numerical approach to treat optimal control problems and we conclude with an application of the results in the bidimesional model of autonomous underwater vehicle.