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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
341

Misstag eller konspiration? : En kvalitativ gestaltningsanalys av Fria Tiders skildringar av mordet på före detta statsminister Olof Palme / Mistake or a conspiracy? : A qualitative framinganalysis of the murder of Olof Palme

Engvall, Aida, Le, Viviann January 2018 (has links)
The Swedish prime minister, Olof Palme was murdered in the middle of the street in the heart of Stockholm, by an unknown perpetrator on the 28th of February 1986. Even though it has been 32 years since the death of the former prime minister, a keen interest of the murder within the media still exists and has not decreased over the years. By conducting a qualitative text analysis, this paper examined how the murder of Olof Palme is described in an alternative medium; Fria Tider. The aim of this study is to problematize citizen journalism in Sweden. With the basis of the framing theory and agenda setting, eight texts were chosen from the alternative medium Fria Tider, an online newspaper. The authors conducted a framing analysis to identify which frameworks were most prominent in the way of describing the murder. The result of this study showed that three frames dominated; a conspiracy of several actors, the police's responsibility, and the solution is near. The authors found that Fria Tider produced several individuals and institutions as suspected of the murder of Olof Palme in these frameworks. While these frameworks can be seen as problematic, this study cannot conclude that it is problematic to read opinions other than what traditional media give. Therefore, this study cannot problematize citizen journalism.
342

[en] DESIGN AND QUALIFICATION OF AN APPARATUS FOR THE EXPERIMENTAL STUDY OF LAMINAR SEPARATION BUBBLES / [pt] PROJETO E QUALIFICAÇÃO DE UM APARATO PARA O ESTUDO EXPERIMENTAL DE BOLHAS DE SEPARAÇÃO LAMINAR

OMAR ELIAS HORNA PINEDO 14 January 2019 (has links)
[pt] O presente trabalho consiste no projeto, construção e qualificação de um aparato para o estudo experimental de bolhas de separação laminar sobre uma placa plana. A previsão do comportamento das bolhas de separação é importante para o projeto de aeronaves, turbinas e geradores eólicos, pois o desprendimento dessas bolhas tem grande impacto na performance de aerofólios. A dinâmica das bolhas não é bem compreendida, além de ser difícil de ser capturada por simulações numéricas que utilizam modelagem da turbulência. Por isso, ensaios experimentais são muito utilizados para a calibração dos modelos utilizados em simulações de engenharia. Neste trabalho, foram criados equipamentos para simular experimentalmente bolhas de separação laminar sobre uma placa plana. Os dispositivos foram projetados para o canal de água do Laboratório de Engenharia de Fluidos da PUC-Rio. O gradiente de pressão necessário para induzir a separação da camada limite e consequente formação da bolha foi ajustado com uma parede falsa, de modo a criar um canal convergente-divergente com a placa plana. Foi projetado um mecanismo de sucção da camada limite na parede falsa para evitar a separação do escoamento nessa superfície. A localização e as vazões de cada ponto de sução foram determinadas com o auxílio de simulações numéricas. Também foi projetado e testado um sistema de sopro e sucção para a excitação de ondas de instabilidade do tipo Tollmien-Schlichting na camada limite da placa plana. O funcionamento de cada dispositivo foi avaliado através da medição da velocidade do escoamento. Para isso, foram empregadas técnicas de medição por velocimetría laser doppler e velocimetría por imagem de partículas. Os resultados obtidos validam o projeto e qualificam o aparato para o estudo de bolhas de separação laminar. / [en] The present work involves the design, construction and performance test of an apparatus for the investigation of laminar separation bubbles in a flat plate boundary layer. Laminar separation bubbles are relevant for many engineering applications and the dynamic of such bubbles has a strong impact on the performance of aircrafts and turbines. The separated boundary layer reattaches to the surface due to the laminar-turbulent transition in the bubble region. This dynamic process is highly challenging for flow simulation tools used for engineering purposes. Thus, there is a demand for experimental studies that can be used for calibration of models present in those simulation tools. To this end, an apparatus was designed and built for the water channel of the Laboratory of Fluid Engineering at PUC-Rio. The boundary layer separation on the flat plate was induced by imposing a constant adverse pressure gradient to the flow. To this end a false wall was built, in order to form a converging-diverging channel with the flat plate. Flow separation on the false wall was avoided using a suction mechanism that was designed to reduce locally the boundary layer thickness. Location of suction and suction flow rates were determined with aid of numerical simulations. In addition, it was designed and built a disturbance source to generate Tollmien-Schlichting waves in the boundary layer of the flat plate. This device was used to trigger the boundary layer transition in a controlled manner. All equipment were tested and their designs were validated against experimental measurements. Laser Doppler anemometry and Particle Image Velocimetry techniques were adopted for assessment of each equipment. Results validate the design and show that separation bubbles can be investigated in detail using this apparatus.
343

Speculative bubbles and contagion: analysis of volatility’s clusters during the DotCom bubble based on the dynamic conditional correlation model

Kohn, Maximilian-Benedikt Herwarth Detlef 24 September 2015 (has links)
Submitted by Maximilian-Benedikt Koehn (mb@koehn.cc) on 2015-10-27T13:40:42Z No. of bitstreams: 1 MasterThesis_FGV_MBK-2.pdf: 1998443 bytes, checksum: f5b2dd679c9a165738dd916b469de18e (MD5) / Rejected by Ana Luiza Holme (ana.holme@fgv.br), reason: Maximilian, In second page, the date is incorrect, it should be 2015. Also the pages numeration in the thesis is incorrect, it should started at the first page of the thesis but the number only appear in the introdution. and it should be at the bottom of the pages. Ex: Introdution is page 10 so in the bottom of the page you see the number 10. Also you didn't write the acknowledgement. It's mandatory in the thesis. Ana Luiza Holme 3799-3492 on 2015-10-27T13:49:55Z (GMT) / Submitted by Maximilian-Benedikt Koehn (mb@koehn.cc) on 2015-10-29T11:50:38Z No. of bitstreams: 1 MasterThesis_FGV_MBK_Final.pdf: 1963111 bytes, checksum: 7788e02d7ef86d4824fb7f131629e4d5 (MD5) / Rejected by Ana Luiza Holme (ana.holme@fgv.br), reason: Duplicidade, Duplicity on 2015-11-03T11:55:29Z (GMT) / Submitted by Maximilian-Benedikt Koehn (mb@koehn.cc) on 2015-11-03T14:54:38Z No. of bitstreams: 1 MasterThesis_FGV_MBK.pdf: 2335793 bytes, checksum: 0ce05e9480acae0f9da905ae2e91f3ba (MD5) / Approved for entry into archive by Ana Luiza Holme (ana.holme@fgv.br) on 2015-11-03T15:13:09Z (GMT) No. of bitstreams: 1 MasterThesis_FGV_MBK.pdf: 2335793 bytes, checksum: 0ce05e9480acae0f9da905ae2e91f3ba (MD5) / Made available in DSpace on 2015-11-03T15:16:18Z (GMT). No. of bitstreams: 1 MasterThesis_FGV_MBK.pdf: 2335793 bytes, checksum: 0ce05e9480acae0f9da905ae2e91f3ba (MD5) Previous issue date: 2015-09-24 / Reviewing the definition and measurement of speculative bubbles in context of contagion, this paper analyses the DotCom bubble in American and European equity markets using the dynamic conditional correlation (DCC) model proposed by Engle and Sheppard (2001) as an econometrical - and on the other hand the behavioral finance as an psychological explanation. Contagion is defined in this context as the statistical break in the computed DCCs as measured by the shifts in their means and medians. Even it is astonishing, that the contagion is lower during price bubbles, the main finding indicates the presence of contagion in the different indices among those two continents and proves the presence of structural changes during financial crisis. / Revendo a definição e determinação de bolhas especulativas no contexto de contágio, este estudo analisa a bolha do DotCom nos mercados acionistas americanos e europeus usando o modelo de correlação condicional dinâmica (DCC) proposto por Engle e Sheppard (2001) como uma explicação econométrica e, por outro lado, as finanças comportamentais como uma explicação psicológica. Contágio é definido, neste contexto, como a quebra estatística nos DCC’s estimados, medidos através das alterações das suas médias e medianas. Surpreendentemente, o contágio é menor durante bolhas de preços, sendo que o resultado principal indica a presença de contágio entre os diferentes índices dos dois continentes e demonstra a presença de alterações estruturais durante a crise financeira.
344

Electrosynthèse assistée par ultrasons de nanoparticules de fer à valence zéro : étude de la croissance de dépôts et de leur dispersion par ondes acoustiques / Ultrasounds assisted electrosynthesis of zero valence iron nanoparticles : study of the deposit growth and dispersion by acoustic waves

Iranzo, Audrey 25 November 2016 (has links)
La synthèse de nanoparticules de fer zéro-valent, par le couplage des procédés d'ultrasonication et d'électrodéposition, est étudiée selon deux approches. La première partie de l'étude s'intéresse à l'influence du substrat, utilisé pour l'électrodéposition, sur la croissance des dépôts de fer et sur leur dispersion par ultrasonication. L'énergie interfaciale ainsi que l'énergie d'adhésion du dépôt sur le substrat (Y_(Fe/substrat) et W_(Fe/substrat) respectivement) étant reliées à l'énergie de surface et à la rugosité du substrat, un intérêt particulier a été porté à ces deux propriétés. Ainsi, deux matériaux présentant des énergies de surface différentes, l'or (Au) et le carbone vitreux (VC), ainsi que des rugosités différentes ont été testés. Un développement théorique basé sur les interactions de Van der Waals a permis de démontrer que Y_(Fe/VC)>Y_(Fe/Au) ce qui suggère une meilleure affinité du dépôt de fer avec l'or qu'avec le VC. Cette différence influence la morphologie (croissance 2D sur or et 3D sur le VC) mais aussi l'adhésion des dépôts. En effet, les expériences réalisées pour étudier l'effet des ultrasons sur le dépôt de fer révèlent une dispersion du dépôt progressive et complète pour le cas du VC alors qu'aucun détachement du dépôt n'est obtenu en utilisant l'or. La seconde partie de l'étude est consacrée à la synthèse de nanoparticules de fer par une nouvelle approche : l'électrodéposition de dépôts de fer ramifiés est étudiée dans une cellule de Hele-Shaw intégrant un élément vibrant (diaphragme piézoélectrique) permettant à la fois la formation de dépôts de fer et leur fragmentation. Les expériences menées révèlent que les bulles d'hydrogène, formées lors de la co-réduction des protons libres durant l'électrodéposition du fer, influencent fortement le processus de fragmentation. En utilisant des hautes fréquences et amplitudes de vibration du PZT, les bulles d'hydrogène oscillent avec des déformations de surface. Celles-ci génèrent des vitesses d'interface suffisamment hautes (˜ 4 m/s) pour permettre aux bulles de fragmenter des dépôts ramifiés en particules de fer, de tailles comprises entre 1 µm et 100 nm, et présentant une grande surface spécifique due à leur morphologie dendritique. Cette deuxième partie de l'étude permet d'ouvrir la voie à une nouvelle technologie de fabrication des nanoparticules. / This study concerns the coupling of the ultrasounds with the electrodeposition process for the synthesis of zero-valent iron nanoparticles; it is structured in two sections. The first focuses on the electrode substrate used for the iron electrodeposition and aims to determine its influence on both the deposit growth and its dispersion by ultrasonication. The interfacial and the adhesion energies of the deposit on the substrate (Y_(Fe/substrate) and W_(Fe/substrate) respectively) being related to the surface energy and the roughness of the substrate, a particular focus is put on the influence of these two properties. Thus, two materials of different surface energies, gold (Au) and vitreous carbon (VC), as well as various roughnesses, are tested. Considering only the Van der Waals interactions, a theoretical development has enabled to determine that Y_(Fe/VC)>Y_(Fe/Au) which suggests a better affinity of the iron deposit with the gold than with the VC substrate. This difference impacts the deposit morphology (2D growth on the gold and 3D growth on the VC substrate) but also the deposit adhesion. Indeed, experiments performed to study the effect of ultrasounds on the iron electrodeposit reveal its progressive and complete dispersion for the vitreous carbon case while no dispersion (no removal of the deposit from the electrode) is obtained with the gold substrate. The second section of the present study deals with the synthesis of iron nanoparticles; to this end, the electrodeposition of branched deposits has been investigated in a Hele-Shaw cell integrating a vibrating element (piezoelectric diaphragm), expected to allow both the deposit formation and its fragmentation. Experiments reveal that the hydrogen bubbles, formed by the co-reduction of free protons during the iron electrodeposition, strongly influence the fragmentation process. Using high vibration frequencies and high amplitudes, the bubbles oscillate with surface deformations, inducing interface velocity sufficiently high (˜ 4 m/s) to allow the fragmentation of the deposit into particles of sizes ranging between 1 µm and 100 nm and showing a high specific surface due to their dendritic morphology. Thus this work opens the way for a new particles manufacturing technology.
345

Développement d'une méthode de pénalisation pour la simulation d'écoulements liquide-bulles / A penalization method for the simulation of bubbly flows

Morente, Antoine 31 October 2017 (has links)
Ce travail est dédié au développement d'une méthode numérique pour la simulation des écoulements liquide-bulles. La présence des bulles dans l'écoulement visqueux et incompressible est prise en compte via une méthode de pénalisation. Dans cette représentation Euler-Lagrange, les bulles supposées indéformables et parfaitement sphériques sont assimilées à des objets pénalisés interagissant avec le fluide. Une méthode VOF (Volume Of Fluid) est employée pour le suivi de la fonction de phase. Une adaptation de la discrétisation des équations de Navier-Stokes est proposée afin d'imposer la condition de glissement à l'interface entre le liquide et les bulles. Une méthode de couplage entre le mouvement des bulles et l'action du liquide est proposée. La stratégie de validation est la suivante. Dans un premier temps, une série de cas-tests est proposée; les objets pénalisés sont supposés en non-interaction avec le fluide. L'étude permet d'exhiber la convergence et la précision de la méthode numérique. Dans un second temps le couplage est testé via deux types de configurations de validation. Le couplage est d'abord testé en configuration de bulle isolée, pour une bulle en ascension dans un liquide au repos pour les Reynolds Re=17 and Re=71. Les résultats sont comparés avec la théorie établie par la corrélation de Mei pour les bulles sphériques propres décrivant intégralement la dynamique de la bulle. Enfin, des simulations en configurations de nuage de bulles sont présentées, pour des populations mono- et bidisperses dans un domaine entièrement périodique pour des taux de vide s'établissant entre 1% et 15%. Les statistiques fournies par les simulations caractérisant l'agitation induite par les bulles sont comparées à des résultats expérimentaux. Pour les simulations de nuages de bulles bidisperses, de nouveaux résultats sont présentés. / This work is devoted to the development of a numerical method for the simulation of two-phase liquid-bubble flows. We use a volume penalization method to take into account bubbles in viscous incompressible flows. The chosen Euler-Lagrange framework involves spherical and nondeformable bubbles represented as moving penalized obstacles interacting with the fluid. A VOF (Volume Of Fluid) method is used to track the phase function while a discretization of the penalized conservation equations is realized to impose slip conditions at the liquid-bubble interface. A coupling method devised from the penalized momentum equations is proposed. The validation process is set as following. First, the fluid is supposed non-acting on the bubbles; several test-cases are presented; we consider configurations with different penalized obstacles shapes (curved channel, inclined channel), the obstacles are either static or dynamic; in each configuration an analytical solution is known. The results show the compliance and the quality of our numerical closures by exposing the convergence order of the method. In order to verify the accuracy of the coupling method, numerical simulations of a 1mm diameter single bubble rising in a quiescent liquid are performed for Re=17 and Re=71. Results are compared with theory established by using Mei correlation for clean spherical bubbles describing the whole dynamics of the rising bubble. Finally, simulations of bubble swarms, in mono- and bidisperse configurations have been carried out in a fully periodic box with moderate void fractions ranging from 1% to 15%. The statistics provided by the simulations characterizing the bubble-induced agitation are compared to experimental results. For the bidisperse bubble swarm configuration, new results are presented.
346

Etude expérimentale de la réduction de traînée par injection de bulles / Experimental study of drag by injection of bubbles

Ndongo Fokoua, Georges 17 December 2013 (has links)
Cette thèse porte sur l’étude expérimentale de la réduction de traînée par injection de bulles. Le contexte de l’étude est lié à la propulsion navale. Les bulles peuvent, lorsqu’elles sont injectées dans la couche limite en développement le long des carènes de navires, contribuer à réduire significativement la résistance de frottement, en allégeant d’une part le fluide le long de la coque et d’autre part en interagissant avec les structures turbulentes de proche paroi. La configuration expérimentale retenue pour cette étude est l’écoulement de Taylor-Couette, avec cylindre extérieur fixe et injection de bulles calibrées. Nos investigations portent sur les régimes de transition, de turbulence naissante et turbulent avec persistance des cellules de Taylor (Re≤20.104). La taille des bulles varie avec le capillaire et le mélange utilisés, entre 0,05 et 0,12 fois la largeur de l’entrefer. Une méthode originale de suivi de la phase dispersée dans un plan méridien, couplée à des mesures de couple global appliqué au cylindre intérieur ont permis de mettre en évidence deux régimes de réduction de traînée et plusieurs types d’arrangements des bulles, en fonction de leur taille et du nombre de Reynolds. Les bulles peuvent avoir une trajectoire glissante, oscillante, être capturées par les cellules de Taylor ou en proche paroi du cylindre intérieur dans les zones de jets sortants. La caractérisation par PIV des vitesses de la phase liquide en monophasique et diphasique a permis d’étudier les modifications induites par les bulles sur la phase liquide et de discuter des mécanismes impliqués dans la modification du couple global par la présence des bulles. Il ressort de cette étude que pour les nombres de Reynolds en deçà de la capture, les bulles contribuent à stabiliser l’écoulement en accord avec une réduction du couple visqueux pouvant atteindre -30% pour des taux de vide très faible (< 1%). Pour des nombres de Reynolds plus élevés, la capture dans les cellules conduit à une réduction de la longueur d’onde axiale et une augmentation de la vorticité des cellules, associée à une augmentation des vitesses rms. Cette configuration est favorable à une augmentation du couple visqueux. A l’inverse, la capture des bulles dans le jet sortant conduit à une augmentation de la longueur d’onde axiale, associée à une diminution de la vorticité. Cette configuration est favorable à une réduction du couple visqueux, moins marquée qu’en absence de capture. / This work presents experimental study of drag reduction by injection of bubbles. Injection of bubbles into the developing boundary layer along the hulls of ships could help to reduce significantly the frictional resistance by lowering a fluid along the hull and interacting with the near-wall turbulent structures. We investigate the interactions between bubbles, the coherent motion and the viscous torque in a Taylor-Couette flow for outer cylinder at rest, while bubbles are injected constantly through a needle. The Reynolds number ranges up to Re≤20.104, for these values of the Reynolds number, Taylor vortices are persistent leading to an axial periodicity of the flow. Bubbles size varies between 0.05 and 0.12 times the width of the gap, depending on the needle and the liquid used. An original method for tracking bubbles in a meridian plane coupled with measures of overall torque applied to the inner cylinder helped to highlight two regimes of drag reduction and various types of arrangements of bubbles, depending on their size and Reynolds number. Bubbles could have a sliding motion, wavering, be captured by the Taylor cells or in the outflow areas near the inner cylinder. Characterization of the liquid velocity by PIV both in single phase and two-phase flow helped to study the modifications induced by the bubbles on the liquid phase and to discuss about the mechanisms involved in the changes induced by the bubbles in the overall torque. The study show that for the Reynolds number before the capture, bubbles could help to stabilize the flow in agreement to the reduction of the viscous torque up to -30% for lowest void fraction (<1%). For the Reynolds number after the capture, bubbles trapped by the Taylor cells lead to a reduction of the axial wavelength and increasing of the vorticity of the cells, associated to an increasing of the rms. This configuration leads to an increasing of the viscous torque. However, bubbles trapped in the outflow areas near the inner cylinder lead to an increasing of the axial wavelength, associated to a decreasing of the vorticity. The configuration supports a smaller reduction of the viscous torque than in the case without captured.
347

Comportement du xénon et de l'hélium dans le carbure de silicium : applications au domaine de l'énergie nucléaire (fission et fusion) / Xenon and helium behavior in silicon carbide : applications for nuclear energy (fission and fusion)

Baillet, Joffrey 29 November 2016 (has links)
Ce travail de thèse s'inscrit dans le cadre des recherches menées sur les matériaux envisagés pour servir dans les réacteurs nucléaires du futur. Parmi ces matériaux, se trouve le carbure de silicium qui est envisagé comme matériau d'enrobage et de gainage du combustible dans les réacteurs à fission ou comme matériau face au plasma ou constituant les couvertures tritigènes dans les réacteurs à fusion (concept DEMO). Des échantillons de β-SiC ont été frittés par Spark Plasma Sintering. Deux gaz rares abondamment produits en réacteur, le xénon et l'hélium, ont été implantés dans SiC à température ambiante et à plusieurs fluences (Φ1 Xe = 5.1015 at.cm-2 et Φ2 Xe = 1.1017 at.cm-2 pour le xénon et Φ1 He = 5.1015 at.cm-2, Φ2 He = 1.1017 at.cm-2 et Φ3 He = 1.1018 at.cm-2 pour l'hélium). Les échantillons irradiés en xénon ont ensuite été recuits à différentes températures (400 °C, 700 °C et 1000 °C). Une amorphisation complète du matériau a été observée pour toutes les fluences sauf Φ1 He (dpamax = 0,2) ainsi qu'une oxydation notable pour les plus hautes fluences. Un seuil de concentration de formation de bulles dans SiC a pu être déterminé pour l'hélium et le xénon. La coalescence de ces bulles à forte concentration s'est traduite par la formation de cloques sur la surface dans le cas de l'implantation à Φ3 He. A Φ2 Xe, des bulles de plusieurs centaines de nanomètres se sont formées dans la phase oxyde (SiO2 amorphe) alors que la coalescence reste très limitée au sein de la phase SiC résiduelle (nanobulles). Aucun relâchement des espèces implantées n a été mesuré jusqu'à une fluence de 1017 at.cm-2. A Φ3 He, un relâchement important d'hélium s'est produit pendant l'implantation, ce qui indique un effet de saturation dans le matériau. Après traitement thermique à 1000 °C, un relâchement conséquent du xénon contenu initialement dans la phase oxyde a été mesuré alors que le xénon contenu dans la phase SiC semble mieux retenu / This work is part of studies on the proposed materials to be used in future nuclear reactors. Among these materials is silicon carbide, which could be used as a cladding or coating material for the fuel in fission reactors, or as a constituent of plasma facing component or breeding blankets in fusion reactors (DEMO concept). β-SiC samples were synthetized by spark plasma sintering. Two rare gases abundantly produced in reactor, xenon and helium, were implanted in SiC at room temperature and at several fluences (Φ1 Xe = 5.1015 at.cm-2 and Φ2 Xe = 1.1017 at.cm-2 for xenon, Φ1 He = 5.1015 at.cm-2, Φ2 He = 1.1017 at.cm-2 and Φ3 He = 1.1018 at.cm-2 for helium). Xenon irradiated samples were then annealed for two hours at different temperatures (400 °C, 700 °C and 1000 °C). A complete amorphization of the material is observed for all fluences except for Φ1 He (maximum dpa level ≈ 0.2). A significant oxidation is observed for the highest fluences. A threshold concentration for bubble formation has been determined for both species. Bubble coalescence at high concentration results in the surface blistering at Φ3 He. Bubbles of several hundred nanometers were formed in the oxide phase (SiO2) after irradiation at Φ2 Xe, while remaining SiC islands are less subject to coalescence (nanometric bubbles). No gas release could be demonstrated up to a fluence of 1017 at.cm-2. For Φ3 He = 1018 at.cm-2, a significant helium release occurs that could indicate a saturation effect within the material. During thermal treatment at 1000 °C, xenon is retained by carbide phase and highly released by oxide phase
348

Experimental Investigation Of The Air-Water Flow Properties In The Cavity Zone Downstream A Chute Aerator

Wargsjö, Ebba, Hedehag Damberg, Albin January 2017 (has links)
Chute aerators are widely used in spillways to avoid cavitation damage. When the water flow passes the aerator, two jets form – upper and lower jet. The purpose of this thesis has been to study the effects from the aerator by conducting experiments in a model with a flow depth large enough to ensure that the upper and lower jet remain separated. This means that the effects from the self-aeration at the upper surface has no effect on the process in the lower jet, thus making it possible to quantify the effects from the aerator. This thesis has also provided information of the bubble formation in the lower jet to aid in the ongoing research at Sichuan University. The following questions were set up for this thesis: • What is cavitation and how is it harmful? • What is the working principle of an aerator? • How is air concentration and bubble frequency distributed in the flow? • How well do the experimental results coincide with theoretical calculations? • How are air bubbles formed and transported within the flow? The effects from the aerator have been quantified by measuring the air concentration and bubble frequency throughout the cavity zone. The model was modified and the velocity was varied between the experiments to study how different parameters effected the aeration. The results indicate that much air is being entrapped in the lower surface, but only a small amount of the entrapped air is being entrained into the flow and that the bubble frequency increases with both distance from the aerator and with an increased flow velocity. No difference in behaviour was noticed between the different modifications of the model. The bubble formation was studied by recording the flow with a high-speed camera. These recordings were used to obtain data about important parameters for the ongoing research at Sichuan University.
349

Analýza výkonnosti čínského akciového trhu / Analysis of performance of the Chinese stock market

Beitl, Marek January 2017 (has links)
The thesis deals with analysis of performance of the Chinese stock market. The first chapter presents basic general characteristics of the stock market and equity investment. The second chapter focuses on the specifics of Chinese stock market. The third, last, chapter analyzes performance of the Chinese stock market.
350

The Selfless Constitution : experimentation&flourishing as the foundations of South Africa's basic law

Woolman, Stu (Stuart Craig) 25 August 2008 (has links)
The way the vast majority of us think about the self, consciousness and free will is incorrect – dramatically out of step with what the majority of neuroscientists, cognitive psychologists scientists and analytic philosophers have to say about those subjects. One consequence of these erroneous views is that the manner in which the majority of us understand ‘freedom’ – as a metaphysical term and as a political concept -- is sharply at odds with how things actually are. We replicate similar kinds of errors when we think about how various forms of human association are constructed and how change actually occurs within such associations. Once again, epistemological fallacies with regard to social theory have the consequence of leading us to attribute far greater ‘freedom’ to groups than they actually possess. This second misattribution of autonomy results in institutional political arrangements and constitutional doctrines at odds with what we know about the human condition. As things stand, the various models of political theory with which the South African Constitutional Court operates rest upon a belief that the rights and freedoms enshrined in the Final Constitution should enable individuals to exercise relatively unfettered control over decisions about the intimate relationships and the various practices deemed critical to their self-understanding. However, individual autonomy as a foundation for constitutional theory overemphasizes dramatically the actual space for self-defining choices. In truth, our experience of personhood, of self-consciousness, is a function of a complex set of narratives over which we exercise little in the way of (self) control. The involuntary and arational nature of identity formation – at the level of both the individual and the social -- requires a constitutional theory that supplants the model of a rational individual moral agent which undergirds much of our current jurisprudence with a vision of the self that is more appropriately located within and determined by the associations to which we all belong. Despite the involuntary and arational nature of identity formation, we can live within communities that determine the greater part of the meaning we make, and still remain committed to the possibility of significant change (for the better) within those communities. This thesis then goes on to explain how a commitment to experimentalism in the political domain, when married to a robust conception of basic entitlements and citizenship, services human flourishing. (To expand the conditions for flourishing, however, is not to make us metaphysically ‘free’ to ‘will’ our actions: a commitment to flourishing reflects an attempt to create an environment in which all inhabitants of South Africa have the opportunity to live lives worth valuing.) Experimental constitutionalism dovetails with a very modest, naturalized account of flourishing because both accounts (1) take the radical givenness of existing constitutive attachments seriously; (2) recognize the boundedness of individual and collective rationality; and (3) describe various kinds of feedback mechanisms that allow for error correction and the enhancement of the conditions of being. Experimental constitutionalism, in particular, enables more citizens to see what ‘works’ and what doesn’t – both with respect to the means and the ends of our existence. Experimental constitutionalism offers the promise of improving the conditions for being by suggesting a range of alterations in constitutional doctrine and a host of changes in the manner in which many political institutions operate. In South Africa, the innovations associated with experimental constitutional design embrace: (1) a doctrine of constitutional supremacy that maintains a meaningful equilibrium with a doctrine of separation of powers, and thus sets relatively clear guidelines for how authority for constitutional interpretation might best be shared by the judiciary, the legislature, the executive and non-state-actors; (2) the use of various standard judicial mechanisms – such as cost orders, court procedures, amici and intervenors, expanded constitutional jurisdiction and structural injunctions – to create bubbles of participatory democracy better able (than courts or legislatures) to resolve various kinds of polycentric conflict; (3) an approach to limitations analysis that provides a better process than ‘balancing’ for experimentalist adjudication; and (4) greater roles for Chapter 9 Institutions with respect to investigation, information-sharing and norm-setting; and (5) a principle of democracy that invites public participation in law-making that will both elicit better information about which government policies work best and effect widespread reflection about the meaning of those constitutional norms that govern our lives. The thesis then (a) mines the brief historical record of two important policy areas – Housing and Education – to show how the principles of experimental constitutionalism have already been put to work and (b) re-examines six Constitutional Court cases to demonstrate how the dual commitment to experimental constitutionalism and flourishing might generate more optimal outcomes. / Thesis (LLD)--University of Pretoria, 2008. / Public Law / unrestricted

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