Tesi sul tema "Bulges on the tube"

La cavéoline est l'un des principaux composants protéiques des cavéoles, qui sont de petites invaginations en forme de coupe dans la membrane plasmique. Il est synthétisé dans le réticulum endoplasmique d'une manière dépendante des particules de reconnaissance du signal et transporté vers l'appareil de Golgi via des vésicules recouvertes de COPII. Au niveau du réseau trans-Golgi (TGN), les complexes de cavéoline 8S s'oligomérisent davantage en complexes 70S avec la facilitation du cholestérol. Ils sont ensuite triés dans des transporteurs par un mécanisme inconnu et transportés vers la membrane plasmique. Le modèle structurel conventionnel de la cavéoline pourrait suggérer qu'il s'agit d'une protéine sensible à la courbure, basée sur sa forme moléculaire en épingle à cheveux. Cependant, un modèle de structure récemment découvert du complexe cavéoline 8S dans les micelles de détergent, basé sur la microscopie cryoélectronique, qui présente une géométrie de disque plat, soulève des questions sur sa sensibilité à la courbure. De plus, les cavins, un autre composant protéique majeur des cavéoles qui coopèrent avec les cavéolines pour plier la membrane pour former des cavéoles, ne s'associent pas aux cavéolines au niveau du TGN. Étant donné qu'aucun autre candidat connu, hormis les cavins, ne peut coopérer avec la cavéoline pour former des transporteurs au TGN, il devient difficile de savoir comment ces transporteurs de cavéoline y sont formés. Par conséquent, dans ce projet, nous avons cherché à élucider la sensibilité à la courbure et l’induction de la cavéoline. Nous avons résolu ces problèmes en reconstituant la cavéoline-1 (Cav1) dans la membrane de vésicules nilamellaires géantes (GUV) et en réalisant des expériences de tirage de tubes. Les résultats ont montré que la cavéoline est effectivement une protéine sensible à la courbure, les complexes de cavéoline 8S présentant une inclinaison d'environ 5 egrés par rapport à l'horizontale, ce qui leur confère une sensibilité à la courbure. De plus, nous avons montré que les complexes de cavéoline 8S peuvent générer collectivement une courbure de la membrane à basse tension et former des échafaudages sur les tubes à haute tension. En résumé, nos résultats ont montré que la cavéoline est une protéine détectant et induisant une courbure, suggérant la possibilité de son tri en transporteurs au TGN sur la base de ces propriétés. De manière intéressante, nous avons observé qu’au-dessus d’une certaine tension membranaire Tt qui dépend de la densité de Cav1, les nanotubes extraits des Cav1-GUV ne présentent plus un rayon constant et que les cavéolines forment des renflements sur le tube. Pour explorer comment Cav1 forme ces renflements, nous avons d'abord observé qu'en moyenne, la taille des renflements diminue avec l'augmentation de la tension membranaire. Nous avons constaté que la taille du renflement est proportionnelle à la quantité totale de cavéoline dans le renflement, ce qui suggère une densité Cav1 constante dans les renflements.De plus, une densité plus élevée de cavéoline dans la membrane favorise la formation de renflements et abaisse le Tt. Ces résultats suggèrent que lorsque le rayon du tube diminue, la cavéoline pourrait induire la formation de renflements pour relâcher les contraintes mécaniques dues à la géométrie tubulaire, mais un modèle et une imagerie haute résolution sont maintenant nécessaires pour expliquer ces observations
Caveolin is one of the major protein components of caveolae, which are small cup-shaped invaginations in the plasma membrane. It is synthesized in the endoplasmic reticulum in a signal recognition particle-dependent manner and transported to the Golgi apparatus via COPII-coated vesicles. At the trans-Golgi network (TGN), caveolin 8S complexes further oligomerize into 70S complexes with the facilitation of cholesterol. They are then sorted intotransport carriers through an unknown mechanism and transported to the plasma membrane. The conventional structural model of caveolin might suggest it is a curvature-sensing protein based on its hairpin molecular shape. However, a recently discovered structure model of the caveolin 8S complex in detergent micelles based on cryo-electron microscopy, which exhibits a flat disc geometry, raises questions about its curvature sensitivity.Furthermore, cavins, another major protein component of caveolae that cooperate with caveolins in bending the membrane to form caveolae, do not associate with caveolins at the TGN. Given that no other known candidate, apart from cavins, can cooperate with caveolin to form transport carriers at the TGN, it becomes unclear how these carriers for caveolin are formed there. Therefore, in this project, we aimed to elucidate the curvaturesensitivity and induction of caveolin. We addressed these issues by reconstituting caveolin-1 (Cav1) into the membrane of giant unilamellar vesicles (GUVs) and by performing tube-pulling experiments. The results showed that caveolin is indeed a curvature-sensing protein, with caveolin 8S complexes exhibiting approximately a 5 degree tilt from the horizontal, which endows them with curvature sensitivity. Furthermore, we showed that caveolin 8S complexes can collectively generate membrane curvature at low tension and form scaffolds on the tubes at high tension. In summary, our results showed that caveolin is a curvature-sensing and -inducing protein, suggesting the possibility of its sorting into transport carriers at the TGN based on these properties. Interestingly, we observed that above a certain membrane tension Tt that depends on Cav1 density, nanotubes pulled from Cav1-GUVs no longer exhibit a constant radius and that caveolins form bulges on the tube. To explore how Cav1 form these bulges, we first observed that on average, bulges' size decreases with an increase in membrane tension. We found that the bulge size is proportional to the total amount of caveolin in the bulge, suggesting a constant Cav1 density in the bulges. Additionally, higher density of caveolin in the membrane favors bulge formation and lowers Tt. These results suggest that when the tube radius decreases, caveolin might induce formation of bulges to relax mechanicalconstraints due to the tubular geometry, but a model and high resolution imaging are now needed to explain these observations

Les tubes métalliques de précision sont largement utilisés pour des applications biomédicales. De tels tubes sont fabriqués par étirage à froid car ce procédé garanti le meilleur aspect de surface, le plus grand contrôle des dimensions du tube et le contrôle des propriétés mécaniques. L'objet de cette étude est de modéliser le procédé d'étirage de tube sur mandrin afin d'en améliorer la compréhension et de construire un outil permettant l'optimisation du procédé et de prédire la rupture des tubes en étirage. La construction du modèle élément finis s'appuie sur la réalisation d'essais expérimentaux afin de caractériser les propriétés mécaniques des matériaux et le frottement entre le tube et les outils d'étirage (mandrin, filière). Le comportement mécanique des alliages est caractérisé par des essais de traction sur tube, des essais de traction sur des éprouvettes découpées dans différentes orientations dans un tube déplié et des essais de gonflement de tube. Pour ces derniers, une machine et un outillage de gonflement de tubes ont été développés spécifiquement. Par le biais de ces essais différents aspects ont été étudiés : la viscoplasticité, l'anisotropie plastique, l'hétérogénéité des propriétés dans l'épaisseur du tube, la thermomécanique. Les coefficients de frottements ont été identifiés par analyse inverse sur des essais d'étirage instrumentés par des cellules d'effort. Des essais d'étirage ont été spécifiquement conçus en modifiant la géométrie du mandrin afin de conduire à la rupture des tubes lors de l'étirage. L'objectif de tels essais étant d'identifier la limite de formabilité des tubes. L'approche choisie pour prédire de la rupture a été d'utiliser des critères de ruptures qui pouvaient être calibrés sur des essais de traction uniquement. Les critères ont été calculés au cours de la simulation numérique de l'étirage sur mandrin et ils ont été évalués par rapport à leur capacité à prédire les réductions de section et d'épaisseur maximales. Enfin, des méthodes analytiques de calcul d'effort d'étirage ont été développées et comparées à la modélisation éléments finis.

Dans le cadre d’une contribution à la modélisation des caloducs oscillants, le modèle mis en place se résume à une bulle seule se déplaçant dans un tube de dimension capillaire.Une densité volumique de chaleur est considérée dans la paroi du capillaire, et la température de référence considérée n’est pas la température de saturation de la phase vapeur,mais la température extérieure au tube ce qui permet la variation de la température de saturation dans le temps et une meilleur adéquation du modèle avec la réalité. La résolution du modèle est effectuée par étapes selon la technique de perturbation du domaine,et les effets physiques de moindres importances peuvent être ajoutés au problème simplifié, en particulier les effets inertiels. Cette résolution a permis de définir une nouvelle corrélation portant sur la hauteur de film déposé par le bouchon liquide en mouvement en fonction du nombre capillaire et d’un nombre d’évaporation représentant l’intensité du chargement thermique. Ce modèle permettra aussi d’étudier l’influence réciproque des champs de vitesse et de température sur le bouchon de liquide devant le ménisque en déplacement. La résolution du problème associé à la partie arrière de la bulle met en évidence la formation d’un bourrelet de liquide entre le film de liquide déposé à la paroi et le ménisque arrière. La taille de ce bourrelet est fortement dépendante de la densité de flux de chaleur imposée à la paroi. Dans le cas o`u le ménisque arrière remouille un film adsorbé laissé à la paroi après assèchement du film, la ligne triple présente des ondulations axiales dues à son déplacement, et non au chargement thermique. La densité de flux de masse évaporée à l’interface liquide-vapeur entraîne une modification non seulement de la température de saturation, mais aussi de la masse de la bulle. Un modèle thermodynamique de la phase vapeur a ´et´e mis en place pour étudier les paramètres importants influençant les variations temporelles des caractéristiques géométriques et thermodynamiques de la bulle
The model of a single bubble moving in a capillary tube is written as a contribution to the modeling of Pulsating Heat Pipes. A constant heat load is considered at the wall, and the reference temperature of the problem is defined to be the outside medium temperature, which is closer to reality, and thus allowing the saturation temperature of the vapor phase to vary. Using domain perturbation techniques, a step-by-step resolution ofthe model is implemented, allowing minor physical effects to be taken into consideration,for example the inertial effect on the receding meniscus. A new correlation is proposed on the thickness of the liquid film deposited by the receding meniscus, by means of the capillary number and an evaporation number representing the thermal condition. The velocity and temperature fields in the liquid plug ahead of the meniscus can also be obtained. The resolution of the problem associated with the rear-end of the bubble,where the rear meniscus advances on either a micrometric liquid film or an adsorbed film left by the dry-out of the capillary wall, shows a corrugating liquid-vapor interface.The magnitude of these corrugations is strongly dependent on the value of the heat load applied at the wall. In the case of wall rewetting, the interface corrugations at the triple line are due to its displacement, and not to the thermal boundary condition. Because the evaporative mass flux through the liquid-vapor interface modifies the vapor bubble mass, a complete transient thermodynamical model of the bubble is implemented. In this case, the important parameters controlling the kinematics, dynamics and thermodynamics of the bubble were identified

Etude de la separation des phases. Description potentielle de la structure de l'ecoulement monophasique. Modelisation des recirculations dans le te a l'aide de la theorie de la ligne de jet et d'une methode des singularites. Etude experimentale par anemometrie laser doppler, traitement d'images, attenuation de rayon x

Etude du comportement du melange diphasique en ecoulement ascendant et descendant. Determination de la perte de charge par frottement avec et sans air, du taux de gaz global, des differents regimes d'ecoulement de la dispersion gaz liquide, du coefficient de transfert de matiere et de l'apport specifique nominal

The bulge forming process is a method for shaping tubular components using an internal hydrostatic pressure combined with a compressive axial load. Initial investigations involved carrying out an extensive literature survey to determine the components which could be formed and the effects of using lubricants and different tube materials. Die-blocks were designed to produce tee pieces, cross joints and off-set joints, and electronic on-line instrumentation was incorporated so that the forming pressures and loads could be accurately monitored. A series of tests were carried out in the forming of: (1) tee pieces, cross joints and off-set joints from copper tubes of two different wall thicknesses, (2) tee pieces using different types of plungers, (3) tee pieces using die-blocks coated with various lubricants, (4) tee pieces from aluminium, copper and steel tubes, (5) tee pieces using die-blocks with various branch radii. From the resulting components, formed with various combinations of internal pressure and compressive axial load, the limits for a successful forming operation were established. Further analysis of these components was then undertaken to evaluate the effects of the internal pressure and axial load on the bulge height and the wall thickness in the deformation zone. From these results, which have been illustrated graphically, the greatest effect on the resulting bulge can be seen to be the compressive axial load. Theoretical analyses are presented, which predict the wall thickness distribution around the bulge zone and also the axial loads required in the forming process. Comparison of these predictions with the experimental results shows fairly good agreement.

L'objet de cette thèse est d'étudier expérimentalement et théoriquement les régimes permanents et oscillants observés lors de la vidange et du remplissage de réservoirs. La première partie concerne l'étude de la vidange continue d'un tube par l'intermédiaire d'une bulle infinie (bulle de Dumitrescu-Taylor). L'étude expérimentale de la dynamique de ces bulles est menée en fonction de la forme de la section du tube, de la viscosité et de la tension de surface. Dans le domaine des grands nombres de Reynolds, la longueur pertinente pour l'étude de la dynamique s'avère être le périmètre mouillé tandis qu'`a faible nombre de Reynolds, c'est la surface de la section qui pilote la dynamique. La seconde partie est consacrée `a l'étude aux temps longs (régime permanent) du remplissage et de la vidange de réservoirs cylindriques. On montre expérimentalement que les bulles infinies jouent un rôle central dans les processus de vidange et de remplissage de réservoirs. Le temps court des oscillations, i.e. la période d'apparition des bulles d'air, est ensuite étudié dans les deux configurations vidange-remplissage. Dans le cas de la vidange, le rôle de la poche d'air compressible présente au fond du tube est mis en évidence ; ce phénomène s'apparente au "glouglou" de la bouteille que l'on vide. Dans le cas du remplissage, on montre la présence d'un oscillateur de nature différente.

A major aim of current astrophysical research is the development of models of galaxy formation that are consistent with observational data. Until recently, the main tools of such research were broadband colours. However, the Lick system of indices has recently provided researchers with a more accurate tool for probing galaxy populations. The work in this thesis compares Lick indices in bright elliptical galaxies with those in the bulges of spiral galaxies, in an effort to compare, contrast and constrain their star formation histories. Long-slit spectroscopic observations of line-strengths and kinematics were carried out along the minor axes of 32 galaxies (ellipticals, SOs and spiral bulges). This study shows bulges to have central line-strengths comparable with those of single stellar populations of approximately solar metallicity or above. In bulges, central line-strengths are shown to lie close to, or within, the loci defining solar abundance ratio SSPs. The large number (24) of indices measured in this study, in conjunction with models of the effects of varying abundance ratios, permit the breaking of age/metallicity degeneracy and allow estimation of enhancements in specific light elements. Estimates of luminosity-weighted age, metallicity and abundance ratio show that, while early-type galaxies exhibit a large range of ages (2 to 13 Gyr), bulges are generally younger, and less enhanced in light elements. Trends involving age and metallicity also differ between early and late types. An anti-correlation is found between age and metallicity in early-type galaxies in the sample, while, in bulges, metallicity is correlated with velocity dispersion. Metallicity gradients are detected in all galaxies in the sample. Age gradients are also detected. No gradients are detected in abundance ratios. A "single zone with in-fall" model of galactic chemical evolution is used to constrain star formation histories of the galaxies observed. It is shown that monolithic collapse models can not reproduce the line-strengths observed in either early- or late-type galaxies. However, models including more extended star formation (e.g. mergers or secular evolution) can. The results of this work are, therefore, at odds with the received wisdom that bulges and elliptical galaxies are old and coeval, with indices in bulges more consistent with secular evolution models of formation, and those in early-type galaxies more consistent with merger models.

In this thesis, we investigate the internal kinematics and stellar populations of a subsample of the bulges of nearby galaxies defined by Balcells & Peletier (1994). To do that we have analysed minor axis spectroscopic data of the sample together with Integral Field observations of one the most interesting galaxies in it (NGC7332). We introduce, for the first time, the use of single-burst stellar population models to obtain stellar velocities, velocity dispersions and higher order Gauss-Hermite moments (h_3, h_4) from galaxy spectra in the near-infrared Ca II triplet region. We detect small-amplitude minor-axis rotation, generally due to inner isophotal twists as a result of slightly triaxial bulges or misaligned inner disks. Velocity dispersion profiles, which extend well into the disk region, show a wide range of slopes. Flattened bulges tend to have shallower velocity dispersion profiles. The inferred similarity of radial velocity dispersion profiles of bulge and disk supports the interpretation of these bulges as thickened disks. We also investigate the position of our sample on the fundamental plane of early-type galaxies. We find that bulges, both in the B and K band, lie close to but slightly below the relation defined by ellipticals and S0s. The most deviant point is NGC7332, whose offset w.r.t the FP cannot be explained by measurement errors. Besides, there are hints that bulges of later morphological type are situated below the other bulges in our sample. The fact that bulges lie so close to the FP of ellipticals and S0s implies that their formation epoch must have been similar to that of cluster Es and S0s. We then proceed to present measurements of near-IR Ca triplet (CaT, CaT*), Paschen (PaT) and Magnesium (MgI) indices for the same sample. We find that CaT* decreases with central velocity dispersion (sigma) with small scatter, unlike other metal indices that generally increase. Our result shows that the CaT* - sigma relation is independent of galaxy type from ellipticals to intermediate-type spirals. Finally we have made use of SAURON observations to unravel the origin of peculiar features in the S0 galaxy NGC7332. We have discovered a Kinematically Decoupled Core, found kinematic evidence for a central disk and mapped a rather disturbed gas distribution counter-rotating w.r.t the stellar body of the galaxy. 2D stellar populations maps reveal that NGC7332 is young everywhere. The fact that we see gas inflow now, together with many features indicates that there must have been gas infall for Gyrs in a row, leading to a continuum formation of this galaxy.

2006/2007
In this thesis I develop a chemical evolution model which takes advantage of the most recent high-quality abundance observations in the Galactic bulge to put constraints on its formation and evolution and to obtain a baseline model for bulges in general. I adopt updated massive star nucleosynthesis and follow the evolution of several alpha-elements and Fe by varying the evolutionary parameters. The [alpha/Fe] ratios in the bulge are correctly predicted to be supersolar for a wide range in [Fe/H], and the stellar metallicity distribution is reproduced assuming a short formation timescale, a high star formation efficiency and an initial mass function flatter than the disk. Metallicity-dependent oxygen yields with stellar mass loss are included in the chemical evolution models for the bulge and the solar neighbourhood. The agreement between predicted and observed [O/Mg] trends above solar metallicity is significantly improved; a normalisation problem probably indicates that the adopted semi-empirical yields need adjustment. The difference between [O/Fe] and the other [alpha/Fe] ratios in the bulge and solar neighbourhood is explained. I test the so-called universal initial mass function, suitable for ellipticals and disks, to see if the bulge stellar metallicity distribution can be reproduced by varying the yields for very massive stars, and included M31 in my analysis. I show that assuming a flatter initial mass function than the universal one is necessary, and that a variation exists in the initial mass function among different environments. Finally, I investigate the evolution of spiral bulges hosting Seyfert nuclei, with detailed calculations of the galactic potential and of the feedback from the central supermassive black hole in an Eddington-limited accretion regime. New spectro-photometrical evolution codes covering a wide range of stellar ages and metallicities allowed to model the photometric features of local bulges. I successfully predict the observed black hole-host bulge mass relation. The observed present-day nuclear bolometric luminosity is achieved only for the most massive bulges, otherwise a rejuvenation is necessary. The observed high star formation rates and metallicities, constancy of chemical abundances with the redshift and bulge present-day colours are reproduced, but a steeper initial mass function is required to match the colour-magnitude relation and the present K-band bulge luminosity.
In questa tesi, ho sviluppato un modello di evoluzione chimica che si avvale di recenti osservazioni ad alta qualità di abbondanze chimiche nel bulbo della Via Lattea, per porre dei vincoli sui suoi meccanismi di formazione ed evoluzione e ottenere un modello generale per i bulbi di spirale. Ho adottato una nucleosintesi aggiornata per le stelle massicce e seguito l'evoluzione di diversi elementi-alpha e del ferro, variando i parametri evolutivi. Si prevede correttamente che i rapporti [alpha/Fe] nel bulbo siano soprasolari per un ampio intervallo in [Fe/H]. La distribuzione in metallicità è riprodotta con un tempo di formazione breve, un'alta efficienza di formazione stellare e una funzione iniziale di massa più piatta che nel disco. Yields di ossigeno con perdita di massa stellare in funzione della metallicità sono stati inclusi nei modelli di evoluzione chimica del bulbo e dei dintorni solari. L'accordo tra gli andamenti di [O/Mg] previsti e osservati per metallicità soprasolari risulta sensibilmente migliorato; si spiega inoltre la differenza tra il rapporto [O/Fe] e gli altri [alpha/Fe] nel bulbo e nei dintorni solari. Un problema di normalizzazione indica che probabilmente gli yields semi-empirici adottati necessitano una revisione. Ho verificato se con la cosiddetta funzione iniziale di massa universale, adeguata per galassie ellittiche e dischi, la distribuzione in metallicità stellare del bulge può essere riprodotta calibrando gli yields delle stelle supermassicce, includendo M31 nell'analisi. Si dimostra che una funzione iniziale di massa più piatta di quella universale è necessaria, e che esiste una variazione nella funzione iniziale di massa tra i diversi ambienti. Infine, ho studiato l'evoluzione di bulbi di spirali che ospitano galassie di Seyfert, mediante calcoli dettagliati del potenziale galattico e del feedback dal buco nero supermassiccio centrale in un regime di accrescimento limitato dal tasso di Eddington. Nuovi codici spettro-fotometrici che coprono un ampio intervallo di età stellari e di metallicità hanno permesso di modellizzare le caratteristiche fotometriche dei bulbi locali. La relazione osservata tra massa del buco nero e del bulbo ospite è prevista con successo. La luminosità bolometrica nucleare misurata al tempo presente si consegue solo per i bulbi più massicci, negli altri casi è necessario un "ringiovanimento". Le osservazioni di alto tasso di formazione stellare, alte metallicità, invarianza di abbondanze chimiche col redshift e colori dei bulbi locali sono riprodotte; una funzione iniziale di massa più ripida è invece richiesta per la relazione colore-magnitudo e la luminosità dei bulbi in banda K al tempo presente.
XX Ciclo
1979

L’aspirateur d’une centrale hydroélectrique est l’organe hydraulique se situant en aval de la roue. Il a une forme divergente afin de récupérer l’énergie cinétique résiduelle en sortie de roue sous forme de pression statique et augmenter ainsi la chute nette de la centrale. Dans le cas des turbines de basse chute de type bulbe, les pertes de charge dans l’aspirateur influencent fortement le rendement global de la centrale. La prédiction correcte de ces pertes de charge au cours du dimensionnement de la turbine représente donc un enjeu majeur. La prédiction numérique des pertes de charge dans l’aspirateur est un réel challenge car l’écoulement dans l’aspirateur est dynamiquement complexe avec des nombres de Reynolds élevés, la présence de swirl et d’un gradient adverse de pression. Ces caractéristiques font que les approches de modélisation classiquement utilisées dans l’industrie sont mises en défaut. L’objectif de ce travail est double : (i) améliorer la prédiction de l’écoulement turbulent dans l’aspirateur en utilisant des approches instationnaires URANS et LES et en portant une attention particulière à la description des conditions d’entrée de l’aspirateur et (ii) réaliser une analyse fine des échanges énergétiques dans l’aspirateur pour mieux comprendre l’origine des pertes de charge. Une condition d’entrée instationnaire représentative de l’écoulement en sortie de roue est élaborée pour ces calculs. Les résultats de simulation sont comparés avec des mesures expérimentales afin d’évaluer la capacité prédictive de chaque approche de modélisation de la turbulence (URANS et LES). Cette étape de validation met en évidence l’importance d’une définition correcte des trois composantes de la vitesse en entrée d’aspirateur. L’influence des conditions aux limites du domaine de calcul, à savoir la rugosité de la paroi et la condition de sortie de l’aspirateur, sur les résultats de simulation est évaluée, notamment dans le cas d’une résolution LES. Grâce à une analyse détaillée du bilan d’énergie cinétique moyenne dans l’aspirateur, les phénomènes hydrodynamiques responsables des pertes de charge sont identifiés. Ceci permet d'analyser en détail les différences de prédiction de pertes de charge entre les calculs URANS et LES et d’identifier les pistes d’amélioration de la prédiction numérique de ces pertes. Enfin, cette analyse permet de comprendre l’évolution des pertes de charge observée entre plusieurs points de fonctionnement de la turbine
The draft tube of a hydraulic turbine is the turbine element located downstream of the runner. It has a divergent shape in order to convert the residual kinetic energy leaving the runner into pressure and thus increase the effective head of the turbine. The performances of low head bulb turbines are highly influenced by the head losses in the draft tube. The prediction of these head losses in a design process is thereby a major issue. The numerical prediction of the head losses in the draft tube is a real challenge because the flow in the draft tube is dynamically complex with high Reynolds numbers, a swirl and an adverse pressure gradient. These characteristics render conventional industrial approaches not appropriate. The objective of this work is twofold: (i) to improve the numerical prediction of the turbulent flow in the draft tube by using URANS and LES unsteady approaches and paying special attention to the description of the inlet boundary conditions of the draft tube and (ii) to conduct a detailed analysis of the energy transfers in the draft tube in order to better understand the origin of the head losses. An unsteady inlet boundary condition for the simulations reproducing the flow field at the runner outlet is developed. Numerical results are compared to experimental measurements in order to evaluate the predictive capacity of each turbulence modelling approach (URANS and LES). This validation step highlights the importance of defining properly the three velocity components at the draft tube inlet. The influence on the numerical results of boundary conditions of the calculation domain, such as wall roughness and the outlet boundary condition, is evaluated, in particular in case of LES. Thanks to a detailed analysis of the mean kinetic energy balance in the draft tube, the hydrodynamic phenomena responsible for head losses are identified. The head losses prediction differences between URANS and LES are thus analyzed in detail and possible improvements for the head losses prediction are identified. Finally, this analysis enables to understand the head losses evolution observed between several operating points of the turbine

We examine a sample of 1495 galaxies in the UDS/CANDELS field to determine the evolution of two component galaxies, including bulges and discs, within massive galaxies at the epoch 1 < z < 3 when the Hubble sequence forms. We fit all of our galaxies’ light profiles with a single Sérsic fit, as well as with a combination of exponential and Sérsic profiles. The latter is done in order to describe a galaxy with an inner and an outer component, or bulge and disc component. We develop and use three classification methods (visual, F-test and the RFF) to separate our sample into 1-component galaxies (disc/spheroids-like galaxies) and 2-component galaxies (galaxies formed by an ‘inner part’ or bulge and an ‘outer part’ or disc). We then compare the results from using these three different ways to classify our galaxies. We find that the fraction of galaxies selected as 2-component systems increases on average 50% from the lowest mass bin to the most massive galaxies, and decreases with redshift by a factor of 4 from z = 1 to z = 3. We find that single Sérsic ‘disc-like’ galaxies have the highest relative number densities at all redshifts, and that 2-component galaxies have the greatest increase and become at par with Sérsic discs by z = 1. We also find that the systems we classify as 2-component galaxies have an increase in the sizes of their outer components, or ‘discs’, by about a factor of 3 from z = 3 to z = 1.5, while the inner components or ‘bulges’ stay roughly the same size. This suggests that these systems are growing from the inside out, whilst the bulges or protobulges are in place early in the history of these galaxies. We then extend our study to a broader range in wavelength, using all available bands from the HST in the UDS/CANDELS field (H, J, i and V band) in order to calculate rest-frame magnitudes, stellar masses and SFRs for each component. We show that galaxies which are better fit as 2-component systems can have the stellar masses and star formation rates of their inner and outer components measured accurately. We examine the position of our inner/outer components in the UVJ diagram, finding that the majority of both inner and outer components lie in the star forming region (68% and 90% respectively), but that the inner portions, the likely forming bulges, are dominated by dusty star formation. Furthermore, we show that the outer components of these forming galaxies have a higher star formation rate, and the relative star formation rate increases in outer components (or discs) as redshift decreases. On the other hand, the relative stellar mass of both components remains statistically constant at z < 3. This suggests that mass formed in the outer components of galaxies is being transferred to the inner components. Finally, we find that the presence of an AGN is more common in both 1-component spheroid-like galaxies and 2-component systems (13 ± 3% and 11 ± 2%) than in 1-component disc-like galaxies (3 ± 1%), demonstrating that the formation of a central inner component likely triggers the formation of the central massive black holes in these galaxies. Lastly we explore the properties of spiral galaxies in UDS, GOODS-S and COSMOS CANDELS fields. We use the CANDELS Galaxy Zoo classification to select spiral galaxies, clumpy spiral and smooth discs. We show that galaxies classified as spirals decrease with increasing redshift, although part of this trend is due to redshift effects. After correcting such effects, we find that the number density of spirals galaxies increases by a factor of 14 ± 2 from z = 2.5 to z = 0.5. We find morphological differences between spiral galaxies and smooth discs, with the former being more ‘disky’ and asymmetric, and the latter being more centrally concentrated. We show that spiral galaxies, and in particular clumpy spirals, dominate the star formation at all redshifts, with average SFRs of SFR = 40 ± 3 Moyr−1 and SFR = 50 ± 7 Moyr−1 respectively, and that there is no benefit of having a large mass to produce spiral structures.

The question whether the observed properties of galaxies are imprinted by the initial conditions of their formation or determined by different evolutionary processes is still open. In the local Universe, more than 60% of stars reside in elliptical galaxies and bulges of lenticular and spiral galaxies. Thus, unveiling the paths of bulge formation and evolution ensures a better understanding of galaxies themselves. The current paradigm separates galactic bulges into two broad categories, namely classical and disk-like bulges. In this scenario, we focus on the description of the bulge component in nearby galaxies from an observational point of view. We aim to properly interpret how observed properties of bulges provide evidences of different mechanisms responsible for their formation and evolution. Indeed, the separation of bulge types according to their observed properties has become a common task in extragalactic astronomy, even if there are no unambiguous ways of doing it yet. We present the technical procedures followed to characterize the structural properties of the bulge component as well as to determine its three-dimensional shape. We elucidate how the photometric algorithm allows to describe the surface brightness distribution of galaxies. We also revise and fine-tune the procedures and methods adopted to constrain the three-dimensional shape of bulges, detailing both the geometrical and statistical analysis. We describe the two-dimensional multi-component photometric decomposition of 404 galaxies from the Calar Alto Legacy Integral Field Area (CALIFA) data release 3. We provide the community with an accurate photometric characterization of the multiple stellar structures shaping the CALIFA galaxies, describing them with the suitable combination of a nuclear point source, a bulge, a single or double bar, and a pure exponential or double-exponential disk component. Moreover, we use a human-supervised approach to evaluate the optimal number of structures to be accounted for fitting the surface brightness distribution. We release the photometric parameters of the CALIFA galaxies, together with statistical errors and a visual analysis of the quality of each fit. The analysis of the photometric components reveals a clear segregation of the structural composition of galaxies with stellar mass. At high masses (log(M_star/M_sun) > 11), the galaxy population is dominated by galaxies modeled with a single Sérsic or a bulge+disk with a bulge-to-total luminosity ratio B/T > 0.2. At intermediate masses (9.5 < log(M_star/M_sun) < 11), galaxies described with bulge+disk and B/T < 0.2 are preponderant, whereas, at the low mass end (log(M_star/M_sun) < 9.5), the prevailing population is constituted by galaxies modeled with either pure disks or nuclear point sources+disks (i.e., with no discernible bulge). We set the basis for new studies combining photometric information with the wealth of two-dimensional spatially resolved spectroscopic information provided by the CALIFA survey. In an effort to push the limits of the scaling relations studied so far to the very low-sigma regime we describe the small bulges at the end of the Hubble sequence. To this aim, we derive the photometric and kinematic properties of 9 nearby late-type spiral galaxies. We analyze the i-band images of the Sloan Digital Sky Survey (SDSS) of these galaxies to characterize the structural parameters of their bulges by means of a two-dimensional photometric decomposition. Moreover, we measure the line-of-sight stellar velocity distribution within the bulge effective radius from the long-slit spectra taken with high spectral resolution at the Telescopio Nazionale Galileo. Finally, we combine the photometric and kinematic information of the sample bulges to study their location in the fundamental plane, Kormendy, and Faber-Jackson relations defined for elliptical galaxies and large bulges. We find that each of our bulge follows the same scaling relations of elliptical galaxies, massive bulges, and compact early-type galaxies so they cannot be classified as disk-like systems. This analysis suggests that a single population of galaxy spheroids follows the same scaling relations, where the mass seems to lead to a smooth transition in the photometric and kinematic properties from less to more massive bulges and elliptical galaxies. The thorough description of the bulge structural features in the CALIFA sample results in the characterization of the bulge three-dimensional shape. Constraining the intrinsic shape of bulges allows to provide new clues on the bulge formation mechanisms and set new limitations for future simulations. Firstly, we take advantage of GalMer numerical simulations to estimate the reliability of the procedure. Thus, we create a set of mock SDSS i-band images at different galaxy inclinations for a set of simulated galaxies, that closely resemble lenticular galaxies. We perform a two-dimensional photometric decomposition of all the mock images applying the same procedure as for real galaxies, in order to characterize the geometrical parameters of bulge and disk which we use to recover the bulge intrinsic shape. We conclude that for galaxies in the inclination range 25° < theta < 65° we can safely derive the intrinsic shape of their bulges. Moreover, we also realize that a very accurate photometric decomposition is mandatory to retrieve the bulge intrinsic shape. Secondly, we obtain the intrinsic shape of 83 bulges from the CALIFA survey. We introduce the (B/A, C/A) diagram to analyze possible correlations between the intrinsic shape and properties of bulges. We find that our CALIFA bulges tend to be nearly oblate systems (66%), with a smaller fraction of prolate spheroids (19%) and triaxial ellipsoids (15%). The majority of triaxial bulges are in barred galaxies (75%). Moreover, we find that bulges with low Sérsic indices or in galaxies with low bulge-to-total luminosity ratios form a heterogeneous class of objects; additionally, bulges in late-type galaxies or in less massive galaxies have no preference for being oblate, prolate, or triaxial. On the contrary, bulges with high Sérsic index, in early-type galaxies, or in more massive galaxies are mostly oblate systems. We conclude that various evolutionary pathways may coexist in galaxies, with merging events and dissipative collapse being the main mechanisms driving the formation of the most massive oblate bulges and bar evolution reshaping the less massive triaxial bulges. Finally, we discuss the observational criteria usually applied to discriminate bulge types in classical and disk-like spheroids. We derive the photometric, kinematic, stellar population, and intrinsic shape properties of bulges in nine lenticular galaxies from the ATLAS3D survey. Our analysis is based on all the observed diagnostics commonly adopted in recent works and tests their efficiency on our sample of meticulously selected systems. Indeed, the morphology of our sample galaxies is chosen to deal with the most simple examples of disk galaxies. We argue that the bulge Sérsic index is a poor tool to discriminate the different bulge types. Moreover, we find that the kinematic properties and line-strength indices of the sample bulges provide no clear identification of the bulge type; this remains true also when comparing the results obtained from the line-strength indices with those obtained from the photometric analysis. We conclude that the common practice of applying the observational criteria for distinguishing bulge types, based on a priori classification according to their morphology or Sérsic index, has to be carefully reconsidered. We remark that, even if the different observational characteristics look well motivated in terms of distinct formation paths, their interplay might result in contradictory outcomes. We propose to characterize the disk-like bulges in terms of their intrinsic shape and dynamical status as the most reliable way to separate them from the classical bulges.
Nell’Universo locale, più del 60% della materia stellare si trova in galassie ellittiche e nei rigonfiamenti centrali, denominati sferoidi, di galassie lenticolari e a spirale. Tuttavia, ancora non si conosce a cosa sia dovuta l’eterogeneità delle loro proprietà osservate. In questo lavoro ci proponiamo di interpretare nel modo più accurato possibile come diversi meccanismi di formazione ed evoluzione possano produrre questa varietà di proprietà. Infatti, determinare gli scenari di formazione ed evoluzione di queste strutture permette una conoscenza più profonda delle galassie stesse. Presento le tecniche di analisi utilizzate per caratterizzare le proprietà strutturali degli sferoidi sia fotometricamente sia geometricamente. Infatti, descrivo gli algoritmi che permettono di analizzare la distribuzione di brillanza superficiale delle galassie e la forma intrinseca tridimensionale dei loro sferoidi. Discuto l’analisi fotometrica delle varie componenti di un campione di 404 galassie nell’ambito della survey Calar Alto Legacy Field Area (CALIFA). Le galassie vengono descritte con una combinazione di modelli, comprendenti sorgenti nucleari, sferoidi, dischi e barre. Ho riscontrato che le galassie più massicce sono meglio modellate con solamente uno sferoide o con sferoide+disco ma con un rapporto di luminosità B/T > 0.2. A masse intermedie, prevalgono le galassie con miglior modello dato da sferoide+disco e B/T < 0.2, mentre nelle galassie meno massicce la componente di sferoide tende a diventare sempre meno importante. Quest’analisi pone le basi per una serie di nuovi studi all’interno della collaborazione di CALIFA. In seguito, caratterizzo gli sferoidi di un campione di nove galassie di tipo morfologico avanzato. Questi sferoidi hanno la peculiarità di essere molto piccoli e presentare una bassa dispersione di velocità. Essi sono stati analizzati da un punto di vista sia fotometrico sia cinematico, usando spettroscopia a fenditura lunga ad alta risoluzione spettrale ottenuta con il Telescopio Nazionale Galileo. Queste proprietà sono state utilizzate per studiare il comportamento del campione di sferoidi nelle relazioni di scala (piano fondamentale, Kormendy, Faber-Jackson). L’analisi evidenzia come un’unica popolazione di sferoidi segua le stesse relazioni di scala, con una transizione nelle proprietà fotometriche e cinematiche osservate dovuta alla loro massa. Successivamente, sempre nell’ambito della survey CALIFA, analizzo la forma intrinseca tridimensionale degli sferoidi in 83 galassie. Utilizzo simulazioni numeriche (Galmer) per testare l’affidabilità del metodo statistico utilizzato per svolgere l’analisi geometrica. Introduco il diagramma (B/A, C/A), che permette di caratterizzare la forma degli sferoidi del nostro campione. Essi sono principalmente oblati (66%), con una piccola frazione di prolati (19%) e triassiali (15%). La maggior parte degli sferoidi triassiali si trova nelle galassie barrate (75%). Attraverso l’analisi della forma intrinseca e delle proprietà osservate degli sferoidi si conclude che il fenomeno di interazione tra galassie è uno dei maggiori responsabili della formazione degli sferoidi oblati più massicci, mentre l’evoluzione della barra tende a formare gli sferoidi triassiali meno massicci. Infine, propongo un’analisi dei criteri solitamente utilizzati in letteratura per discriminare diverse tipologie di sferoidi. A questo proposito vengono analizzati gli sferoidi in nove galassie nell’ambito del progetto ATLAS3D. L’analisi si basa su proprietà sia fotometriche sia spettroscopiche e sulla loro forma intrinseca, I risultati evidenziano come l’indice di Sérsic non sia un buon indicatore per differenziare diversi sferoidi. Invece, la forma intrinseca e lo stato dinamico dello sferoide vengono proposti come miglior combinazioni di parametri per caratterizzare gli sferoidi galattici.

AN ABSTRACT OF THE DISSERTATION OFKimberly Noel Turner, for the Doctor of Philosophy degree in Political Science, presented on June 9, 2021, at Southern Illinois University Carbondale. TITLE: EDUCATION BULGES AND MASS PROTEST: HOW HIGHER EDUCATION INFLUENCES PROTEST ONSET AND OUTCOMESMAJOR PROFESSOR: Dr. Stephen BloomCan trends in higher education attainment explain protest onset and outcomes? Beneficial state development indicators, such as education attainment, may produce detrimental employment outcomes. Nonviolent protests spread throughout the developing world throughout the 2010s, often in countries previously immune to public agitation. At the forefront of these protests were well-educated professionals, often doctors and lawyers. Why did these protests emerge? Why did middle-class groups initiate and lead these protests? How successful were these protests? The education bulge theory provides a framework for explaining the onset and outcomes of nonviolent mass protests in repressive countries. The education bulge theory captures the formation of skilled labor grievance and the spillover that influence the emergence of nonviolent, large and diverse protests. Chapter Two details the education bulge theory. Education bulges occur when a country undergoes sharp increases in university enrollments exceeding global averages. As university graduates increases, so does the supply of skilled labor. An increasing percentage of the population is then impacted when demand for skilled labor wanes, i.e. skills downgrading. Skills downgrading worsens the relative position of university graduates to other educational attainment groups, increasing tertiary unemployment and underemployment. Skilled labor compensates by downshifting, seeking out and competing for positions within the semi-skilled job market. This increased competition for semi-skilled positions pushes other educational groups down and out of the labor market. The global forces of labor polarization, education bulges, and skills downgrading are examined for their roles in inducing downshifting behavior. The fomentation of grievance amongst skilled labor is detailed, as well as the spillover effects for semi and unskilled labor. Flattening supplies of knowledge-intensive positions within the private sector along with public sector hiring reductions in the post-recession period exacerbates the decline of skilled labor’s relative position. Chapter Three examines objective measures of skilled labor’s relative position to other education attainment groups. Alongside theories of economic development and inequality, the education bulge theory is tested for its relationship to protest onset. Governmental expenditures on education, relative unemployment amongst primary, secondary and tertiary education attainment groups, and average wage growth are evaluated for their relationship with education bulges and protest onset. Bivariate and multivariate regression analysis indicate that skills downgrading is significantly increases the odds of protests emerging in highly repressive countries. Under an education bulge, additional governmental spending on tertiary education is positively correlated to protest onset. Do education bulges contribute to the overall successfulness of protests? In Chapter Four, I develop a new cost-benefit approach to measuring protest success. Canonical binary measurement of protest success fails to capture the relative concessions demonstrators might extract from their regimes. I develop a 21-point scale capturing the dimensions of gains protests might achieve (in the form of regime concessions) and the costs they pay for those concessions (in the form of state reprisals). Using Mokken scale analysis, country success scores pinpoint a protest’s position along a unidimensional continuum of abject failure to transformative changes in the body politic is developed. My measure offers an improved method of capturing regime behavior in the form of ‘ignoring’ and active repression. My measure also captures instances where protests may be misclassified as failures and features a stronger correlation for crowd age diversity. However, the success scores and binary measures often share directionality and strength for key causal factors. Thus, I cannot claim a definitive victory for my measure. However, unlike binary measures, my measure is able to offer more accurate confidence intervals for interactive relationships evaluated in Chapter Five. Chapter Five evaluates the relationship between political contexts and protest features. Entrenched leadership and repressive state structures are traditional deterrents to protest success. Education bulges, leadership tenure, and state repressiveness are evaluated for their influence on protest successfulness. Education bulges are found to increase overall protest successfulness. Education bulges are also found to increase crowd size and crowd diversity. Interactive relationships between education bulges, crowd size, and class diversity are examined. Class diversity and education bulges are individual have a positive and significant influence upon protest success. Education bulges are found to moderate class diversity, shifting class diversity’s effect on protest success from positive to negative. Regime concessions and protest successfulness are also influenced by external factors, such as sanctions, defections, and audience sympathy. External actors are more likely to apply reputational, material or defection costs against regimes when protests occur within education bulges and feature class diversity. These costs act as mediators of regime responsiveness. Under a mediated moderation model, the direct and indirect effect of education bulges, crowd size, class diversity, and regime costs are evaluated for their effect on protest successfulness. Education bulges increase reputational costs for regimes while class diversity increases material costs. Crowd size increased both material costs and defections. Education bulge contexts producing diverse and large crowds are more successful than non-education bulge protests. This study offers an examination of the role of higher education attainment upon the emergence and successfulness of nonviolent mass protests in authoritarian states from 2005-2013. Despite data limitations, robust findings indicate that education bulges increase the odds of a stable repressive regime experiencing protest onset and protest success. Failure of central governments to ensure commiserate employment for their growing pools of skilled labor increases grievance, crowd sizes and diversity, and punitive action against governments seeking to repress demonstrators.

There is mounting evidence that supermassive black holes (SMBHs) form and grow in bulgeless galaxies. However, a robust determination of the fraction of active galactic nuclei (AGNs) in bulgeless galaxies, an important constraint to models of SMBH seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been shown to be incomplete for AGNs in low-mass galaxies. In a recent study using the Wide-field Infrared Survey Explorer, we discovered hundreds of bulgeless galaxies that display mid-infrared signatures of extremely hot dust suggestive of powerful accreting massive black holes, despite having no signatures of black hole activity at optical wavelengths. Here we report X-ray follow-up observations of J122434.66+555522.3, a nearby (z = 0.052) isolated bulgeless galaxy that contains an unresolved X-ray source detected at the 3 sigma level by XMM-Newton with an observed luminosity uncorrected for intrinsic absorption of L2-10 (keV) = (1.1 +/- 0.4) x 10(40) erg s(-1). Ground-based near-infrared spectroscopy with the Large Binocular Telescope and multiwavelength observations from ultraviolet to millimeter wavelengths together suggest that J1224+5555 harbors a highly absorbed AGN with an intrinsic absorption of N-H > 10(24) cm(-2). The hard X-ray luminosity of the putative AGN corrected for absorption is L2-10 keV similar to 3 x 10(42) erg s(-1), which, depending on the bolometric correction factor, corresponds to a bolometric luminosity of the AGN of L-bol 6 x 10(43)-3 x 10(44) erg s(-1). and a lower mass limit for the black hole of M-BH similar or equal to 2 x 10(6) M-circle dot, based on the Eddington limit. While enhanced X-ray emission and hot dust can be produced by star formation in extremely low metallicity environments typical in dwarf galaxies, J1224+5555 has a stellar mass of similar to 2.0 x 10(10) M-circle dot and an above solar metallicity (12 + logO/H = 9.11), typical of our WISE-selected bulgeless galaxy. sample. While collectively. these observations suggest the presence of an AGN, we caution that identifying obscured AGNs in the low-luminosity regime is challenging. and often requires multiwavelength observations. These observations suggest that low-luminosity AGNs can be heavily obscured and reside in optically quiescent galaxies, adding to the growing body of evidence that the fraction of bulgeless galaxies with accreting black holes may be significantly underestimated based on optical studies.

Spiral galaxies contain large amounts of interstellar dust, that absorbs and scatters their photons. This results in strong distortions and changes of their observed stellar images from what would be observed in the absence of the dust. Because of this the measured structural parameters of spiral galaxies, and indeed, knowledge of some of the most fundamental physical attributes of galaxies - their stellar distributions - is strongly biased. I present here the results of a study to quantify the effects of dust on the derived photometric parameters of disks (old stellar disks and young stellar disks) and bulges in spiral galaxies: scale-lengths, axis-ratios, central surface-brightness, effective radii and Sersic indices. The goal of this study is to provide corrections for dust effects to observers by following the procedures and algorithms they use to perform surface brightness photometry of real images of galaxies. The changes in the derived photometric parameters from their intrinsic values (as seen in the absence of dust) were obtained by fitting simulated images of disks and bulges produced using radiative transfer calculations. The fits to the simulations were performed using GALFIT 3.0.2 data analysis algorithm and the fitted models were the commonly used infinitely thin disks described by exponential, general Sersic and de Vaucouleurs distributions. The analysis was done firstly for disks and bulges seen in isolation (thus quantifying dust and projection effects) and subsequently for the same morphological components seen together (thus quantifying the dust effects on bulge-disk decomposition). This is the first time a systematic and self-consistent quantification of these effects has been performed covering the whole parameter space and all photometric parameters of spiral galaxies and its constituent stellar components. The approach proposed here allows a clear separation of projection effects, dust effects and decomposition effects, through chain corrections. For single morphological components, I find the young stellar disks to suffer the most severe variation in the photometric parameters due to dust effects. In this context I also present corrections for narrow line (Balmer line) images. Old stellar disks are also significantly affected by dust, in particular when fits are performed with exponential functions. The photometric parameters of bulges are to a lesser extent affected by dust. I also find that the variation of dust corrections with face-on dust opacity and inclination is similar for bulges with different intrinsic stellar emissivities (different Sersic index), with differences manifesting only close to edge-on orientations of the disk. Dust corrections for bulges are found to be insensitive to the choice of the truncation radius and ellipticity of the bulge. I find that dust effects on the photometric parameters of decomposed disks and bulges increase with the Sersic index of bulge intrinsic volume stellar emissivity distribution and depend on the bulge-to-disk ratio for galaxies with bulge stellar emissivity described by higher Sersic index functions. All the numerical results are listed in the Appendices and made available to the scientific community.

Augalo derlingumo didinimas ir derliaus kokybės gerinimas – vienas iš svarbiausių žemės ūkio mokslų prioritetų. Valgomoji bulvė (Solanum tuberosum L.) – svarbus maisti-nis augalas, kurio auginimo ir paplitimo geografija didesnė nei kukurūzų, ryžių ir kviečių. Pagrindinė bulvių produkcija – stiebagumbiai, kurie naudojami ne tik maistui, pašarui, bet ir alternatyviems tikslams: bioplastikų, krakmolo, spirito gamybai (Šlapakauskas, Du-chovskis, 2008). Bulvių pasėlio augimas labai priklauso nuo sėklai naudojamų stiebagumbių koky-bės. Pagal fiziologiją bulvė sudėtingas augalas, kurio augimo, vystymosi bei stiebagumbių laikymo sąlygos įtakoja jų dygimą (Cristiansen et al., 2006). Bulvių stiebagumbių dygi-mas – vienas iš svarbiausių veiksnių, nulemiančių kero stiebų skaičių, kurie yra derlių įtakojantis faktorius (Allen et al., 1992). Siekiant paankstinti derlių, suformuoti tankų, produktyvų pasėlį stiebagumbių daigi-nimui gali būti naudojami egzogeniniai augimo reguliatoriai – sintetiniai fitohormonų analogai, kurie leidžia pakeisti augalo hormonų statusą, modifikuoti metabolizmo proce-sus. J. Lazauskas (2001) teigia, kad geriausia bulves daiginti natūraliomis šviesos sąlygo-mis, ne aukštesnėje nei 17 oC temperatūroje, 35–45 dienas iki sodinimo, tuomet jų daigai būna trumpi ir stiprūs. Tačiau kai stiebagumbių daiginimo metu trūksta šviesos ar būna netinkama temperatūra, pumpurai būna ne vienodo dydžio, silpni. Mokslininkai plačiai tiria abiotinių veiksnių (šviesos, temperatūros)... [toliau žr. visą tekstą]
Research problem. Plant productivity enhancement and yield quality improvement are one of the top priorities for agricultural sciences. The potato (Solanum tuberosum L.) is a staple crop, whose cultivation and distribution geography is larger than that of maize, rice and wheat. The main potato produce is tubers which are used not only for food and feed but also for alternative purposes – production of bioplastics, starch and spirits (Šlapakauskas, Duchovskis, 2008). Potato crop performance is highly reliant on the quality of tubers used as seed material. In terms of physiology, the potato is a complex plant whose growth, development and tuber storage conditions influence sprouting (Cristiansen et al., 2006). Potato tuber sprouting is one of the prime factors determining the number of stems per potato plant, which is also a factor, which influences potato yield (Allen et al., 1992). Seeking to advance potato maturity and harvesting and to achieve a dense, productive stand, exogenous growth regulators can be used for tuber sprouting. These growth regulators are synthetic analogues of phytohormones that enable changes in plant hormonal status and modification of metabolic processes. J. Lazauskas (2001) suggests that to achieve short and strong sprouts, it is most efficient to sprout potato tubers under natural light conditions at a temperature no higher than 17 oC, 35–45 days prior to planting. However, a shortage of light during tuber sprouting or inadequate temperature result... [to full text]

We present a recalibration of the M-BH-sigma(star) relation, based on a sample of 16 reverberation-mapped galaxies with newly determined bulge stellar velocity dispersions (sigma(star)) from integral-field spectroscopy (IFS), and a sample of 32 quiescent galaxies with publicly available IFS. For both samples, sigma(star) is determined via two different methods that are popular in the literature, and we provide fits for each sample based on both sets of sigma(star). We find the fit to the active galactic nucleus sample is shallower than the fit to the quiescent galaxy sample, and that the slopes for each sample are in agreement with previous investigations. However, the intercepts to the quiescent galaxy relations are notably higher than those found in previous studies, due to the systematically lower sigma(star) measurements that we obtain from IFS. We find that this may be driven, in part, by poorly constrained measurements of bulge effective radius (r(e)) for the quiescent galaxy sample, which may bias the sigma(star) measurements low. We use these quiescent galaxy parameterizations, as well as one from the literature, to recalculate the virial scaling factor f. We assess the potential biases in each measurement, and suggest f = 4.82 +/- 1.67 as the best currently available estimate. However, we caution that the details of how sigma(star) is measured can significantly affect f, and there is still much room for improvement.

Abstract : This project aims at the simulation, design, fabrication and testing of a microscale shock tube. A step by step procedure has been followed to develop the different components of the microscale shock tube and then combine them together to realize the final device. The document reports on the numerical simulation of flows in a microscale shock tube, the experimental study of gas flow in microchannels, the design, microfabrication, and the test of a microscale shock tube. In the first step, a one-dimensional numerical model for simulation of transport effects at small-scale, appeared in low Reynolds number shock tubes is developed. The conservation equations have been integrated in the lateral directions and threedimensional effects have been introduced as carefully controlled sources of mass, momentum and energy, into the one-dimensional model. The unsteady flow of gas behind the shock wave is reduced to a quasi-steady laminar flow solution, similar to the Blasius solution. The resulting one-dimensional equations are solved numerically and the simulations are performed for previously reported low Reynolds number shock tube experiments. Good agreement between the shock structure simulation and the attenuation due to the boundary layers has been observed. The simulation for predicting the performance of a microscale shock tube shows the large attenuation of shock wave at low pressure ratios. In the next step the steady flow inside microchannels has been experimentally studied. A set of microchannels with different geometries were fabricated. These microchannels have been used to measure the pressure drop as a function of flow rate in a steady compressible flow. The results of the experiments confirm that the flow inside the microscale shock tube follows the laminar model over the experiment's range of Knudsen number. The microscale shock tube is fabricated by deposition and patterning of different thin layers of selected materials on the silicon substrate. The direct sensing piezoelectric sensors were fabricated and integrated with microchannels patterned on the substrate. The channels were then covered with another substrate. This shock tube is 2000 µm long and it has a 2000 µm wide and 17 µm high rectangular cross section equipped with 5 piezoelectric sensors along the tube. The packaged microscale shock tube was installed in an ordinary shock tube and shock waves with different Mach numbers were directed into the channel. A one-dimensional inviscid calculation as well as viscous simulation using the one-dimensional model have also been performed for the above mentioned geometry. The comparison of results with those of the same geometry for an inviscid flow shows the considerable attenuation of shock strength and deceleration of the shock wave for both incident and reflected shock waves in the channel. The comparison of results with numerically generated results with the one-dimensional model presents good agreement for incident shock waves. // Résumé : Ce projet vise à la simulation, la conception, la fabrication et l'essai d'un tube à choc a l'échelle micrométrique. Une procédure étape par étape a été suivie pour développer les différentes composantes du tube à choc à l'échelle micrométrique, puis les assembler pour la réalisation finale du dispositif. Le document rend compte de la simulation numérique, de l'étude expérimentale de l'écoulement du gaz dans les microcanaux, de la conception, de la microfabrication, et de l'essai d'un tube à choc à l'échelle micrométrique. Dans la première étape, un modèle numérique unidimensionnel pour la simulation des effets de transport à des petites échelles dans des tubes à choc à faible nombre de Reynolds, est développé. Les équations de conservation ont été intégrés latéralement et les effets tridimensionnels ont été mis en place avec des sources bien contrôlées de masse, du moment et de l'énergie, dans un modelé à une dimension. L'écoulement non stable du gaz après le choc est réduit à un flux laminaire quasi permanent, solution similaire à la solution de Blasius. Les équations unidimensionnelles résultantes sont résolues numériquement et des simulations sont effectuées pour des expériences précédemment rapportées de tube à choc en faible nombre de Reynolds. II y a une bonne correspondance entre la structure du choc et la simulation. L'atténuation due à la couche limite a été observée. La simulation pour prédire les performances d'un tube à choc à l'échelle micrométrique a montré la grande atténuation de l'onde de choc à faible taux de pression. Dans l'étape suivante, le flux constant à l'intérieur des microcanaux a été étudié expérimentalement. Quelques microcanaux avec différentes géométries ont été fabriqués. Ces microcanaux ont été utilises pour mesurer la chute de pression en fonction du débit dans un écoulement compressible flux stable. Les résultats de l'expérience confirment que l'écoulement à l'intérieur du tube à choc à l'échelle micrométrique suit le modèle laminaire sur un large éventail de nombre de Knudsen. Le tube à choc à l'échelle micrométrique est fabrique par les dépôts et gravure des différentes couches minces de certains matériaux sur un substrat de silicium. Des capteurs piézoélectriques à détection directe sont fabriques et intégrés avec les microcanaux caïques sur le substrat. Les canaux sont ensuite recouverts d'un autre substrat. Le tube à choc est long de 2000 µm et a une section rectangulaire de 2000 µm de large et 17 µm de haut et es téquipé avec 5 capteurs piézoélectriques dans le tube. Le tube à choc à l'échelle micrométrique est installé dans un tube à choc standard afin d'entre exposés à une onde de choc avec différents nombres de Mach. Un calcul unidimensionnel inviscide ainsi que la simulation visqueuse avec le modèle unidimensionnel a aussi été effectué pour cette géometrie. La comparaison des résultats avec ceux obtenus avec la même géométrie avec avec un flux Inviscid montre une large atténuation de la force de choc et une décélération de l'onde de choc pour les deux ondes de choc incidentes et réfléchies dans le canal. La comparaison de résultats avec les résultats générés numériquement par modèle unidimensionnel pressent un bon accord pour onde de choc de l'incident.

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Universidade Estadual Paulista (UNESP)
Foi estudada a influência de cinco profundidades de lençol freático no desenvolvimento de bulbos de calla (Zantedeschia sp). As características avaliadas foram: área foliar, número de folhas, número de flores, altura da haste floral, ciclo da cultura, ganho de massa verde do bulbo, evapotranspiração da cultura e eficiência do uso da água. As callas foram cultivadas em estufa de vidro com 50% de redução na radiação interna, plantadas em vasos construídos de tubos de pvc de diâmetro nominal de 150 mm preenchidos com substrato, os bulbos utilizados apresentavam massa verde inicial variando de 10 a 12 g. Os vasos foram colocados em bandejas, com capacidade para seis vasos, as mesmas apresentavam um sistema automático para o abastecimento de água por um reservatório conectado diretamente às bandejas com uma bóia para manutenção do nível do lençol freático constante. As profundidades dos lençóis freáticos foram: 10, 17, 24, 31 e 38 cm. As características referentes ao desenvolvimento da planta foram verificadas ao longo do ciclo, por meio de nove avaliações efetuadas durante o cultivo. A evapotranspiração foi medida diariamente e computada semanalmente e ao término do ciclo. O ganho de massa verde dos bulbos foi avaliado ao final do ciclo de cultivo pela relação entre a massa verde inicial e a massa verde final. A eficiência do uso da água foi checada com base na evapotranspiração da cultura (L.planta-1) e na massa verde final do bulbo (g). Os resultados referentes à área foliar foram variáveis de 1.011,6 a 2.016,3 cm2. O número de folhas emitidas variou de 7,5 a 13,8 folhas por bulbo. Ao longo de todo o ciclo de cultivo o número médio de flores emitidas foi de 0,8 a 1,2 flores por bulbo. Os bulbos apresentaram um aumento variável de 21,7 a 11,7 vezes em relação ao tamanho inicial, ou seja, o ganho de massa verde ao final do cultivo foi na ordem de 2.173 a 1.170%.
The objective was to determine the influence of 5 different table water levels in the crop development of Calla. The parameter evaluated were leaf area, number of leaves, number of flowers, flowers height, growth cycle, tuber increment rate, evapotranspiration of the culture and efficiency in water use. The study was conducted in glass greenhouse with 50% percent of sunlight reduction. The plants were grown in PVC pots with diameter of 150 mm, which were filled with substrate. The plant tubers weigthed from 10 g to 12 g. The pots were placed within containers, at a rate of six per container, where the water replacement was authomatically determined by a buoy, which kept the water level constant. The table water levels used were 10, 17, 24, 31 and 38 cm. The crop development parameters were checked in nine evaluations during the growth cycle. Evapotranspiration was evaluated weekly and at the end of the cycle. The increment in tuber weigth was determined from the initial and final fresh weight. The water use efficiency was determined from the culture evapotranspiration (mm) and from the final fresh weigth (g). The results show that leaf area varied between 1,011.6 and 2,016.3 cm2. The number of leaves varied from 7.5 and 13.8 leaves per tuber. The number of flowers produced per tuber throughout their whole life cycle was 0.8 and 1.2. The plant tubers presented a size increment which ranged from 21.7 times to 11.7 times their initial size, which represented an increment of fresh weigth at the end of the culture of 2,173% and 1,170%. The evapotranspiration of the whole culture was 46.14 L/planta and 26.89 L/planta. The efficiency in water use varied between 4.5 g/L and 6.9 g/L. The data set was submitted to the F and Tukey statistical tests, to allow for comparisons of average results. Was found statistical discrepancy in the growth cycle parameter, between 38 cm table water level, which life cycle was 281 days, and 10 and 24 cm table water levels.

Ce travail est une contribution à l'étude de la convection dans les faisceaux tubulaires. Les effets de l'orientation des tubes et de l'électrogénération de bulles en paroi sont étudiés. Les investigations sont expérimentales. Une méthode électrochimique (la polarographie) est utilisée pour la détermination des coefficients de transfert de matière. La thèse se compose de deux parties. Les travaux de la première partie consistent en la détermination expérimentale des lois de perte de charge et de coefficient d’échange dans un faisceau de cylindres. L’écoulement est caractérisé par une incidence variable par rapport aux tubes et des nombres de Reynolds élevés. Les essais sont réalisés en écoulement monophasique dans des faisceaux de tubes inclinés, à pas carré en ligne, de pas réduit : 1. 45 et pour cinq inclinaisons différentes de l’écoulement, allant de la direction transversale à la direction de l’axe des tubes. Les coefficients de transfert sont mesurés par la méthode polarographique. Une correlation empirique est ainsi obtenue puis comparée à celles proposées dans le littérature. Une corrélation de perte de charge est également obtenue, déduite de mesures de pression statique. L’échange de matière sur les plaques porte-tubes à également été étudié, dans le cas du faisceau transversal. Enfin, nous avons complété cette première partie par des essais spécifiques au problème des générateurs de vapeur, concernant l’influence de différentes géométries de plaques entretoises sur le transfert en aval de la plaque (en écoulement axial). Dans la deuxième partie, nous avons déterminé expérimentalement les coefficients d’échange, en écoulement forcé sans bulles d’abord, en présence d’électrogénération gazeuse ensuite. L’écoulement sur le cylindre de mesure est transversal et de faible vitesse. Dans un premier cas, nous avons étudié le transfert de chaleur entre un cylindre chauffé et un écoulement transversal de solution de KOH 1N. La même étude est reprise pour le cylindre situé dans un faisceau de tubes ne participant pas à l’échange. L’arrangement des tubes dans le faisceau est en quinconce. Dans un second cas, nous avons étudié le transfert de matière sur le cylindre à l’aide de la technique polarographique. Il est ensuite placé dans un faisceau de tubes, pour une étude similaire. Enfin, pour compléter cette deuxième partie, nous avons effectué des essais dans un échangeur de chaleur à faisceau tubulaire

Inertance Tube Pulse Tube Cryocoolers (ITPTC) are a class of rugged and high-endurance refrigeration systems that operate without a moving part at their low temperature end, and are capable of reaching 4 K or lower. ITPTCs are suitable for application in space vehicles, and attempts are underway worldwide to improve their performance and miniaturize their size. The thermo-fluidic processes in ITPTC are complicated, however, and the details of the mechanisms underlying their performance are not well understood. Elucidation of these underlying processes is the objective of this investigation. In this study, the commercial computational fluid dynamic (CFD) package Fluent䵠was utilized for modeling the entire large ITPTC system that includes a compressor, an after cooler, a regenerator that is represented as a porous medium, a pulse tube, cold and warm heat exchangers, an inertance tube, and a reservoir. The simulations represent a fully-coupled system operating in steady periodic mode, without any arbitrary assumptions. The objective was to examine the extent of multi-dimensional flow effects in an inertance tube pulse tube cryocoolers, and their impact on the performance of these cryocoolers. Computer simulations were performed for two complete ITPTC systems that were geometrically similar except for the length-to-diameter ratios of their regenerators and pulse tubes. For each ITPTC system three separate simulations were performed, one with an adiabatic cold-end heat exchanger (CHX), one with a known cooling heat load, and one with a pre-specified CHX temperature. Each simulation would start with an assumed uniform system temperature, and continue until steady periodic conditions were achieved. The results indicate that CFD simulations are capable of elucidating the complex periodic processes in PTCs very well. The simulation results also show that a one-dimensional modeling of PTCs is appropriate only when all the components of the PTC have very large aspect ratios (i.e., L/D >>1). Significant multi-dimensional flow effects occur at the vicinity of component-to-component junctions, and secondary-flow recirculation patterns develop, when one or more components of the PTC system have small aspect ratios. The simulation results, although limited in scope, also suggest that ITPTCs will have a better overall performance if they are made of components with large aspect ratios.

Orientador: Antonio Evaldo Klar
Banca: João Carlos Cury Saad
Banca: Magali Ribeiro da Silva
Banca: Rubens Duarte Coelho
Banca: Tais Tostes Graziano
Resumo: Foi estudada a influência de cinco profundidades de lençol freático no desenvolvimento de bulbos de calla (Zantedeschia sp). As características avaliadas foram: área foliar, número de folhas, número de flores, altura da haste floral, ciclo da cultura, ganho de massa verde do bulbo, evapotranspiração da cultura e eficiência do uso da água. As callas foram cultivadas em estufa de vidro com 50% de redução na radiação interna, plantadas em vasos construídos de tubos de pvc de diâmetro nominal de 150 mm preenchidos com substrato, os bulbos utilizados apresentavam massa verde inicial variando de 10 a 12 g. Os vasos foram colocados em bandejas, com capacidade para seis vasos, as mesmas apresentavam um sistema automático para o abastecimento de água por um reservatório conectado diretamente às bandejas com uma bóia para manutenção do nível do lençol freático constante. As profundidades dos lençóis freáticos foram: 10, 17, 24, 31 e 38 cm. As características referentes ao desenvolvimento da planta foram verificadas ao longo do ciclo, por meio de nove avaliações efetuadas durante o cultivo. A evapotranspiração foi medida diariamente e computada semanalmente e ao término do ciclo. O ganho de massa verde dos bulbos foi avaliado ao final do ciclo de cultivo pela relação entre a massa verde inicial e a massa verde final. A eficiência do uso da água foi checada com base na evapotranspiração da cultura (L.planta-1) e na massa verde final do bulbo (g). Os resultados referentes à área foliar foram variáveis de 1.011,6 a 2.016,3 cm2. O número de folhas emitidas variou de 7,5 a 13,8 folhas por bulbo. Ao longo de todo o ciclo de cultivo o número médio de flores emitidas foi de 0,8 a 1,2 flores por bulbo. Os bulbos apresentaram um aumento variável de 21,7 a 11,7 vezes em relação ao tamanho inicial, ou seja, o ganho de massa verde ao final do cultivo foi na ordem de 2.173 a 1.170%.
Abstract: The objective was to determine the influence of 5 different table water levels in the crop development of Calla. The parameter evaluated were leaf area, number of leaves, number of flowers, flowers height, growth cycle, tuber increment rate, evapotranspiration of the culture and efficiency in water use. The study was conducted in glass greenhouse with 50% percent of sunlight reduction. The plants were grown in PVC pots with diameter of 150 mm, which were filled with substrate. The plant tubers weigthed from 10 g to 12 g. The pots were placed within containers, at a rate of six per container, where the water replacement was authomatically determined by a buoy, which kept the water level constant. The table water levels used were 10, 17, 24, 31 and 38 cm. The crop development parameters were checked in nine evaluations during the growth cycle. Evapotranspiration was evaluated weekly and at the end of the cycle. The increment in tuber weigth was determined from the initial and final fresh weight. The water use efficiency was determined from the culture evapotranspiration (mm) and from the final fresh weigth (g). The results show that leaf area varied between 1,011.6 and 2,016.3 cm2. The number of leaves varied from 7.5 and 13.8 leaves per tuber. The number of flowers produced per tuber throughout their whole life cycle was 0.8 and 1.2. The plant tubers presented a size increment which ranged from 21.7 times to 11.7 times their initial size, which represented an increment of fresh weigth at the end of the culture of 2,173% and 1,170%. The evapotranspiration of the whole culture was 46.14 L/planta and 26.89 L/planta. The efficiency in water use varied between 4.5 g/L and 6.9 g/L. The data set was submitted to the F and Tukey statistical tests, to allow for comparisons of average results. Was found statistical discrepancy in the growth cycle parameter, between 38 cm table water level, which life cycle was 281 days, and 10 and 24 cm table water levels.
Doutor

Pulse tube refrigerators (PTR) are robust, rugged cryocoolers that do not have a moving component at their cold ends. They are often employed for cryogenic cooling of high performance electronics in space applications where reliability is paramount. Miniaturizing these refrigerators has been a subject of intense research interest because of the benefits of minimal size and weight for airborne operation and because miniature coolers would be an enabling technology for other applications. Despite much effort, the extent of possible PTR miniaturization is still uncertain. To partially remedy this, an investigation of the miniaturization of pulse tube refrigerators has been undertaken using several numerical modeling techniques. In support of these models, experiments were performed to determine directional hydrodynamic parameters characteristic of stacked screens of #635 stainless steel and #325 phosphor bronze wire mesh, two fine-mesh porous materials suitable for use in the regenerator and heat exchanger components of miniature PTRs. Complete system level and pulse tube component level CFD models incorporating these parameters were then employed to quantitatively estimate the effects of several phenomena expected to impact the performance of miniature PTRs. These included the presence of preferential flow paths in an annular region near the regenerator wall and increased viscous and thermal boundary layer thicknesses relative to the pulse tube diameter. The effects of tapering or chamfering the junctions between components of dissimilar diameters were also investigated. The results of these models were subsequently applied to produce successively smaller micro-scale PTR models having total volumes as small as 0.141 cc for which sufficient net cooling was predicted to make operation at cryogenic temperatures feasible. The results of this investigation provide design criteria for miniaturized PTRs and establish the feasibility of their operation at frequencies up to 1000 Hz with dimensions roughly an order of magnitude smaller than those that have recently been demonstrated, provided that challenges related to their regenerator fillers and compressors can be addressed.

Producing axi-symmetrical parts with holes from tubular stock by tube upsetting is a frequently used technique in industry. There are basically four types of tube upsetting process
external, internal, simultaneous internal and external upsetting, and expanding of tube. In general, tubular parts require more than one upsetting stage. In industry, generally trial-error methods, which require lots of time and effort depending on experience, are used for the design of stages. Wrong design causes failures during production. On the other hand, the problems, which are likely to be encountered in manufacturing, can be observed and solved in the design stage by using finite element analysis. In this study, the finite element analyses of external, internal, simultaneous internal and external tube upsetting, and tube expanding processes have been realized. During the analyses, the part and the die geometries at the intermediate stages, which have been designed according to the proposed procedures, have been used. The stress and strain distributions and die filling actions have been observed during the process. The process design and die geometries have been evaluated according to the finite element results. It has been seen that the recommended procedures generally generate acceptable designs. In some cases, it has been noted that minor modifications may be required on the design.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Letras/Inglês e Literatura Correspondente, Florianópolis, 2014.
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Abstract : The problem addressed in the present study concerns William Shakespeare's plays in performance on television, most specifically the presence of violence in BBC's production of Titus Andronicus, directed by Jane Howell. I have come up with two sets of hypotheses. The first is that the violence identifiable in the playtext seems to have been recreated by Howell through the specificities of the medium, making such violence neither excessively gory nor comic. The second is that Jane Howell's utilization of alienating devices in Shakespeare's first tetralogy, as pointed out by Graham Holderness, can also be verified in Titus Andronicus. Such elements may be related to the aforementioned treatment of violence in the play and may serve as a way of making political or aesthetic commentaries on the play itself. Thus, in order to approach my corpus I relied on television and performance studies and Bertolt Brecht?s and some of his commentators' writings on epic theater. I have also brought to my work the voices of critics about the violence in the play itself, most importantly Francis Barker's notions on the "occlusion of violence" in Titus Andronicus. The present thesis concludes that Brechtian elements are indeed present in Howell's production and that, to a certain extent, they are related to the violence in Titus Andronicus. However, this relationship is complex. At the same time that the extravagant violence is hidden from the spectator and alienation devices every now and then distance the audience from the characters and the action, Young Lucius' reaction to this same, often-unseen violence is highlighted.

The first chapter assesses the impact of the cohort size on labour market outcomes. Using exogenous variation and micro-level data for France, the UK and the US, we study the effect of supply shocks measured at different ages on unemployment rates and wages during a cohort's life cycle. The results from an IV estimation show that the largest magnitude of the effects is found when the cohort size is measured at age 25. The impact of both wages and unemployment rates are temporary, however, both decreasing with time. The second chapter analyses the effects of large inflows of foreign students on English undergraduates. Our results confirm previous findings that there is no overall effect, but we identify changes in the distribution of natives. We find that top performing English students are crowded in by foreign students. It is also mainly English-born males, natives who do not have English as their mother tongue and those of Asian ethnic origins that are crowded in by foreign students. In chapter three, we aim to understand the short-term effects of changes in the level of the tuition fees charged by English universities on students' geographic mobility. Our results suggest that the increase in tuition fees in 2006/07 charged by English universities led students to enrol into universities that are closer to home, with a larger effect experienced by men and White students. Moreover, we find that students are less likely to move to universities located in rich areas.

La simulation numérique fiable des performances de turbines hydrauliques suppose : i) de pouvoir inclure dans les calculs RANS (Reynolds-Averaged Navier-Stokes) traditionnellement mis en œuvre l'effet des incertitudes qui existent en pratique sur les conditions d'entrée de l'écoulement; ii) de pouvoir faire appel à une stratégie de type SGE (Simulation des Grandes Echelles) pour améliorer la description des effets de la turbulence lorsque des écarts subsistent entre calculs RANS et résultats d'essai de référence même après prise en compte des incertitudes. Les présents travaux mettent en oeuvre une démarche non intrusive de quantification d'incertitude (NISP pour Non-Intrusive Spectral Projection) pour deux configurations d'intérêt pratique : un distributeur de turbine Francis avec débit et angle d'entrée incertains et un aspirateur de turbine bulbe avec conditions d'entrée (profils de vitesse,en particulier en proche paroi, et grandeurs turbulentes) incertaines. L'approche NISP est utilisée non seulement pour estimer la valeur moyenne et la variance de quantités d'intérêt mais également pour disposer d'une analyse de la variance qui permet d'identifier les incertitudes les plus influentes. Les simulations RANS, vérifiées par une démarche de convergence en maillage, ne permettent pas pour la plupart des configurations analysées d'expliquer les écarts calcul / expérience grâce à la prise en compte des incertitudes d'entrée.Nous mettons donc également en ouvre des simulations SGE en faisant appel à une stratégie originale d'évaluation de la qualité des maillages utilisés dans le cadre d'une démarche de vérification des calculs SGE. Pour une majorité des configurations analysées, la combinaison d'une stratégie SGE et d'une démarche de quantification des incertitudes permet de produire des résultats numériques fiables. La prise en compte des incertitudes d'entrée permet également de proposer une démarche d'optimisation robuste du distributeur de turbine Francis étudié
The reliable numerical simulation of hydraulic turbines performance requires : i) to includeinto the conventional RANS computations the effect of the uncertainties existing in practiceon the inflow conditions; ii) to rely on a LES (Large Eddy Simulation) strategy to improve thedescription of turbulence effects when discrepancies between RANS computations and experimentskeep arising even though uncertainties are taken into account. The present workapplies a non-intrusive Uncertainty Quantification strategy (NISP for Non-Intrusive SpectralProjection) to two configurations of practical interest : a Francis turbine distributor, with uncertaininlet flow rate and angle, and a draft-tube of a bulb-type turbine with uncertain inflowconditions (velocity distributions, in particular close to the wall boundaries, and turbulentquantities). The NISP method is not only used to compute the mean value and variance ofquantities of interest, it is also applied to perform an analysis of the variance and identify inthis way the most influential uncertainties. The RANS simulations, verified through a gridconvergence approach, are such the discrepancies between computation and experimentcannot be explained by taking into account the inflow uncertainties for most of the configurationsunder study. Therefore, LES simulations are also performed and these simulations areverified using an original methodology for assessing the quality of the computational grids(since the grid-convergence concept is not relevant for LES). For most of the flows understudy, combining a SGE strategy with a UQ approach yields reliable numerical results. Takinginto account inflow uncertainties also allows to propose a robust optimization strategy forthe Francis turbine distributor under study

Heat transfer tubes suffer erosion when immersed in fluidized beds. This has caused problems, especially in fluidized bed combustors. The mechanism of erosion for horizontal tubes in fluidized beds is not well understood. The purpose of this study was to investigate the erosion mechanism in fluidized beds and to investigate the influence of operating parameters and the mechanical properties of the particles and tube materials. Horizontal tube erosion tests were carried out in a room temperature three-dimensional fluidized bed with a cross-section of 216 mm by 203 mm and height of 1.52 m. Sample rings of ten different materials were mounted on a solid bar and were weighed before and after each test to determine the erosion rate. The parameters tested were particle size (0.30 to 1.51 mm), particle sphericity (0.84 to 1.0), particle density, particle hardness, superficial air velocity (0.88 to 2.52 m/s), tube diameter (15 mm to 32 mm), tube configuration and material mechanical properties. Two additional types of experiments were also conducted to help understand the mechanism of erosion. In one particles were dropped freely in an empty column to impact on test specimens at different velocities determined by the dropping distance, in order to investigate erosion due to solid particle impact under known conditions. In the other the particle movement was filmed in the vicinity of a horizontal tube in a two-dimensional fluidized bed in order to investigate the particle flow pattern around a tube. A small number of tests were also conducted at high temperatures. The erosion of a horizontal tube in fluidized beds was found to be caused mainly by the impact of solid particles on the lower surface. Erosion was found to be strongly dependent on the particle impact velocity, which is closely related to the void (bubble or slug) rise velocity. The void rise velocity, in turn, is determined by the mean void size which depends on the superficial air velocity, column size and other fluidizing conditions. Particle diameter also has a strong influence on erosion. The target material Young's modulus appears to be the major mechanical property which is closely related to the erosion rate caused by solid impact erosion. Of the materials tested, all non-ferrous metals suffer much more erosion than ferrous metals. Localized high particle velocities due to jets and at bends or near feed points can be extremely harmful. The mechanism of erosion caused by low velocity (< 6m/s) solid particle impacts appears to be different than that caused by high velocity (> 30m/s) impacts reported in the literature, although there are some similarities in trends. The erosion at low impact velocities appears to be mainly due to a surface fatigue process, which, instead of plastically deforming a small amount of target material for every impact, deforms the target materials in the elastic range and causes them to crack on or underneath the surface leading to removal of materials.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

This Thesis aims to investigate the relationship between the temporal characteristics of the muscular activity of the Eustachian tube and its opening in adults and children so as to achieve a greater understanding of the mechanisms involved in tubal function during the act of swallowing. This should lead ultimately to a greater understanding of the causes of the high occurrence of middle ear effusion in children. This was accomplished by developing a new methodology for evaluating Eustachian tube function and carrying out experiments on adults and preschool children. A comprehensive review of the literature related to the physiology of swallowing, the anatomy, physiology, and dysfunction of the Eustachian tube is presented which reveals that the above areas of research require further investigation. A new technique which measures tympanic membrane displacement was used as an indicator of Eustachian tube muscular activity, together with the more conventional method of sonotubometry which detects Eustachian tube opening, during experiments upon both adults and children. Evidence from the experimental work revealed differences in the muscular activity of the Eustachian tube between adults and children. The adult group had a larger muscular activity compared to a smaller muscular activity for the preschool children. It was also evident that an aquiescent period of 72 milliseconds exists between the muscular activity of the Eustachian tube and its opening. This was found to be the same for the two subject groups. In addition, using sonotubometry, 50 percent of the preschool children's ears tested showed no positive sound pressure change compared to 2.3 percent of adults. This implied the existence of an immature Eustachian tube opening in preschool children compared to adults. An hypothesis was proposed that a combination of muscular activity and nasal over-pressure is responsible for the Eustachian tube opening in adults compared only to muscular activity alone in preschool children. In the adult group 33 percent of the Eustachian tube opening occurred before the muscular activity of the Eustachian tube compared to 8 percent in the preschool children. In conclusion, it appears that these experimental techniques could form the basis of a clinical diagnostic tool for Eustachian tube function.

Zr-2.5 wt % Nb (Zr-2.5Nb) is the main alloy used in the pressure tubes of CANDU nuclear reactors, which are manufactured by hot extrusion. Pressure tubes are subjected to high irradiation fields and corrosion, in addition to the applied stress at operating temperatures of around 330°C, which leads to irradiation creep that is often life-limiting; re-tubing the reactors, is a source of significant through-life cost of the reactor system. However, significant variability in performance is observed between tubes and stations, which is felt to be due to variability in the fabrication and operation conditions. The performance of Zr-2.5Nb is sensitive to both microstructure and texture and therefore it is desirable to be able to understand the extrusion conditions more fully. In this thesis, the extrusion of Zr-2.5Nb is examined, along with commercially pure titanium (CP Ti), commercially pure magnesium (CP Mg) and AA2014. The effect of extrusion ratio, die geometry and rod versus tube conditions are examined. The resulting microstructures and textures are rationalised with the aid of a finite element model for the process. After the introduction and literature review (Chapters 1-2), the modelling procedure and extrusion theory are examined (Chapter 3). Constitutive data (including friction conditions) are gathered and a Norton-Hoff constitutive model is generated in Chapter 4. It is found that adiabatic heating can be important at high strain rates and low temperatures, particularly in CP Ti and CP Mg. Recrystallization during deformation can be observed in the flow curves, particularly in CP Mg and AA2014 at low strain rates and high temperatures. The extrusion of AA2014 tubes is examined in Chapter 5. It is found that satisfactory textures and microstructures can be obtained, and that the model can reproduce the observed load curves. Partially extruded gridded billets are also used to verify the flow conditions predicted by the model and to obtain textures and microstructures part-way through the extrusion process. The extrusion of CP Mg and CP Ti are examined in Chapters 6 and 7, respectively. It was found that CP Mg recrystallized very easily, dominating the microstructures and textures observed. The CP Ti extrusions were performed in the [alpha]+[beta] regime in order to match Zr-2.5Nb conditions. The high extrusion ratio rod textures were dominated by the [beta]->[alpha]transformation, while those in the tubes were more characteristic of deformation of the [alpha] phase. Zr-2.5Nb extrusion is examined in Chapter 8. Satisfactory microstructures with elongated grains surrounded by thin ligaments of [beta] were obtained in the tube extruded through a flat-faced die, with the expected texture for this ratio of wall to diametral reduction (paragraph 2.5.7.1, Figure 2.25). The microstructures obtained were found to be a product of the temperature in the die and the cooling rate of the material. Excessive cooling rates lead to the production of basket-weave microstructures, and breakup of the grain boundary [alpha] to very fine microstructures. Again, the extrusion modelling allowed the results obtained to be rationalised. Finally, the reader is referred in Chapter 9 for a discussion of the obtained result. Conclusions drawn and suggestions for further work can be found in Chapter 10, together with recommendations for the industrial modelling of tube extrusion and for industrial practice.

If form follows normative discourse in medical design, what happens to the gestalt when you include related discourses of the medical ventilator in the design process? My aim has been to integrate critical industrial design and with an exploratory aesthetic approach. This aesthetic approach aimed to create an on going exchange between the development of concepts inspired by theory and the creative sketching of 3-D form.The medical ventilator can be divided in three parts: 1. The technical part of the machine, 2. The monitor with an interface, and 3. The tubes that is the connection to the patient. In the beginning of the project I was working with the part of the medical ventilator that connects to the patient, ie. the tubes. My methods at this point were conducting interviews with caretakers, filming nurses handling the tube and having informal discussions with doctors and nurses. Using my own embodied experience is also part of my method since I am a licenced voctional nurse with experience from the ICU ward.I began my project by studiyng the part of the ventilator that connects to the patient. After I had been working with the project for some time I started to realise that what I was refering to as an important part of the medical ventilator, was just seen by others as a “tube”. I decided to change the roles, and to work only on the tube, and not on the rest of the apparatus. When I made this discourse shift, I tried to understand why the tube had been neglected in medical design. The tube is de facto an essential part of the ventilator. It is the important link between the patient and the apparatus, and without it, there is no treatment. Despite of this, the ventilator tube is not prioritised in medical design. I used gender theory about hierarchy of power and work division to understand this matter and concluded that the patient has low status in hospital care. Technical intensive care has high status, while patient related care as geriatric care has low status. In similar manner the hierarchy exists in the medical ventilator. The part of the product that contains the technology has high staus, while the part that is low tech and connected to the patient, the ventilator tube, has low status.My combined theoretical and explorative aesthetic approach didn’t only prove to change the gestalt, allowing for bodily form that challenges the constructed dichotomy of the hospital discourse. It also changed the entire focus on the product by making the tube central. It also inspired for a solution moving from a visual interface to a haptic and tactile interface. Some questions this design project attempts to discuss: What does it mean to give bodily form to this medical design project? How does the use of a tactility and haptics interface on a surface that may resemble a soft body help response from the staff and relatives as they encounter with the patient? In what way can the medical design process develop in a way to help patients regain humanity

Doctor of Philosophy
Department of Mechanical and Nuclear Engineering
Steven J. Eckels
The current research presents the experimental investigation of the effect of tube pitch on enhanced tube bundles’ performance. The typical application of this research is flooded refrigerant evaporators. Boosting evaporator’s performance through optimizing tube spacing reduces cost and energy consumption. R-134a with the enhanced tube Turbo BII-HP and R-123 with Turbo BII-LP were used in this study. Three tube pitches were tested P/D 1.167, P/D 1.33, and P/D 1.5. Each tube bundle includes 20 tubes (19.05 mm outer diameter and 1 m long each) constructed in four passes. The test facility’s design allows controlling three variables, heat flux, mass flux, and inlet quality. The type of analysis used is local to one location in the bundle. This was accomplished by measuring the water temperature drop in the four passes. The water-side pressure drop is included in the data analysis. A new method called the EBHT (Enthalpy Based Heat Transfer) was introduced, which uses the water-side pressure drop in performing the heat transfer analysis. The input variables ranges are: 15-55 kg/m².s for mass flux, 5-60 kW/m² for heat flux, and 10-70% for inlet quality. The effect of local heat flux, local quality, and mass flux on the local heat transfer coefficient was investigated. The comparison between the bundle performance and single tube performance was included in the results of each tube bundle. The smallest tube pitch has the lowest performance in both refrigerants, with a significantly lower performance in the case of R-134a. However, the two bigger tube pitches have very similar performance at low heat flux. Moreover, the largest tube pitch performance approaches that of the single tube at medium and high heat fluxes. For the R-123 study, the smallest tube bundle experienced quick decease in performance at high qualities, exhibiting tube enhancement dry-out at certain flow rates and high qualities. The flow pattern effect was demonstrated by the dry-out phenomena. At medium and high heat fluxes, as the tube pitch increases, the performance approaches that of the single tube. All tube bundles experience quick decrease in performance at high qualities. Evidently, P/D 1.33 is the optimum tube pitch for the studied refrigerants and enhanced tubes combinations.

Problems with the identification of tubular fossils from ancient hydrothermal vent and cold seep deposits have hindered understanding of the evolutionary history of vent and seep communities. This thesis aims to (1) improve knowledge of lesser-studied tubicolous annelids occupying vents and seeps, (2) study the diversity of tubes at vents and seeps, (3) investigate the fossilisation of tubes within modern vents and seeps, (4) better interpret the fossil record, and (5) provide insights into the palaeoecology these environments. Results presented here on investigations of Sclerolinum contortum, a species belonging to a little- studied genus of the major vent/seep dwelling annelid family Siboglinidae, demonstrate that it exhibits tube morphological plasticity, wide habitat preferences and a global distribution spanning the Arctic to the Southern Ocean. These results also suggest that this species has dispersed throughout this range using chemosynthetic habitats as stepping stones. A detailed investigation of the full mineralisation process of Alvinella (Alvinellidae) tubes at modern hydrothermal vents shows that these tubes are fossilised by pyrite and silica that template organic tube layers, and that microorganisms living on tube surfaces are also exceptionally well-preserved alongside the tubes. No known ancient vent tube fossils resemble mineralised Alvinella tubes. A major morphological and compositional comparison of both modern and fossil tubes from vents and seeps revealed that two fossil tube types from the Mesozoic were likely made by vestimentiferans (Siboglinidae), suggesting that this major vent and seep annelid lineage has a longer history within vents and seeps than proposed by molecular clock age estimates. This analysis also demonstrates the need for greater caution in assigning affinities to fossil vent and seep tubes. Finally, this thesis reports the remarkable preservation of filamentous microorganisms on the walls of Silurian vent tube fossils, giving the first insights into ecological associations between microbes and metazoans within the oldest known hydrothermal vent community.

The diploma thesis is focused on the analysis of the behavior of the thin-walled tubular test specimen during the technological test of the liquid draining of the tubes. The test specimen ‘in the form a tube was made of austenitic stainless steel 17 240 (1.4301, X5CrNi18-10). During the experiment, the radial expanding tool was quasi-statically charged by the internal fluid pressure. In the introductory part, the thesis focuses on the stress-strain description of the method of tube bulging and possible ways of detecting the strain of material during forming. The experimental part is primarily focused on the analysis of the test sample that was obtained from the experiment. Theoretical approaches were used to analyze the real test sample to detect strain and stress in material, numerical simulation of the bulge process and 3D ATOS scanning device, which helped clarify behavior tube during bulging process. At the end of the thesis is proposed possible design of the tool. This modification should contribute in the future to the full functionality of the radial expanding tool, or the bulging of the tube by liquid.