Thesis (doctoral) - Universität, Duisburg-Essen, 2009. / Includes bibliographical references.

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Lors de la phase de rentrée atmosphérique d'une sonde spatiale, la paroi du corps est le siège de phénomènes physico-chimiques complexes. Nous nous intéressons dans cette thèse au cas où le matériau solide de l'objet de vol comporte plusieurs constituants s'ablatant de façon différentielle. En particulier, l'un de ces constituants subit un changement de phase donnant lieu à l'apparition d'une phase liquide. Nous sommes en présence de trois phases : solide, liquide et gaz. Les travaux effectués dans cette thèse correspondent au développement de méthodes numériques en 2D capables de modéliser les différentes interfaces en présence ainsi que l'évolution des fluides ou des matériaux séparés par celle-ci. L'enjeu principal de la thèse est de proposer des méthodes et des algorithmes de couplage pour l'écoulement diphasique, la thermique multimatériaux et les changements de phase (fusion et sublimation) / During atmospheric reentry phase of a spacecraft, its body surface is the seat of complex physico-chemical phenomena. We focus in this thesis on the case where the wall of the flying object has several components ablating differentially. In particular, one of those components undergoes a phase change giving the rise to the introduction of a liquid phase. We have three phases in the domain: solid, liquid and gas phases.The work done in this thesis corresponds to the development of 2D numerical methods which can modelize the different interfaces. The main issue of this thesis is to propose methods and algorithms for coupling the two-phase flow, multi-material heat problems and phase changes (melting and sublimation).

Denna uppsats analyserar två tal av Sveriges statsminister Stefan Löfven; det ena från Socialdemokraternas partikongress 2015 och det andra från Almedalen samma år. Syftet är att ge en inblick i hur visioner för framtiden uttrycks av en samtida högt uppsatt politiker och att undersöka om det finns några skillnader i hur dessa visioner uttrycks beroende på om talaren i första hand vänder sig till sitt eget parti eller till en bredare opinion. Uppsatsen lyfter fram tre olika aspekter av politiska visioner (praktiska, utopiska och imaginära) och analyserar talen med fokus på dessa. Detta kombineras med en retorisk situationsanalys som syftar till att belysa och förklara skillnader i hur visionerna uttrycks i de två talen. Resultatet visar att de visioner som Löfven uttrycker i båda talen lägger ett större fokus på att lösa omedelbara praktiska problem än att bygga ett framtida samhälle. Det framkommer även att talet från partikongressen mer tydligt kopplar visionerna till socialdemokratin som ideologi än vad talet i Almedalen gör. / This thesis analyses two speeches by the Swedish prime minister Stefan Löfven; one from the Swedish Social Dmocratic Party's congress in 2015 and the other from Almedalen week the same year. The purpose is to provide insight into how visions for the future are expressed by a contemporary high-profile politician and to explore if there are any differences in how these visions are expressed depending on whether the speaker is primarily adressing his own party or a broader public. The thesis features three different aspects of political vision (practical, utopian and imaginary) and anyses the speeches focusing on these. This is combined with an analysis of the rhetorical situations, intended to highlight and explain differences in how the visions are expressed in the two speeches. The results show that the visions expressed by Löfven in both speeches tends to focus more on solving immediate problems than buildning a future society. The thesis also reveals that the speech from the congress connects the expressed visions to social democratic ideology more clearly than the speech from Almedalen Week does.

La notion de schémas gradients, conçue pour les équations elliptiques et paraboliques, linéaires et non-linéaires a l'avantage de fournir des résultats de convergence et d'estimations d'erreur valables pour de nombreuses familles de méthodes numériques (éléments finis conformes et non-conformes, éléments finis mixtes, différences finies ...). Vérifier un ensemble restreint de propriétés suffit pour prouver qu'une méthode numérique donnée rentre dans le cadre de travail des schémas gradients et donc qu'elle sera convergente sur les différents problèmes traités. L'étude du problème de Stefan, celle du problème de Stokes incompressible, ainsi que celle des équations de Navier-Stokes incompressibles sont présentées dans cette thèse, chacune présentant un théorème de convergence établi à l'aide des schémas gradients. Pour Stokes et Navier-Stokes, nous donnerons une preuve de convergence pour les cas stationnaires et transitoires en modifiant certaines hypothèses ce qui aura comme effet de trouver des résultats de convergence différents. Finalement, nous présentons également quatre méthodes (Taylor-Hood, Crouzeix-Raviart, Marker-and-Cell, Hybrid Mixed Mimetic) pour ces deux problèmes et nous vérifions qu'elles rentrent bien dans le cadre des schémas gradients / The notion of gradient schemes, designed for linear and nonlinear elliptic and parabolic problems has the benefit of providing common convergence and error estimates results, which hold for a wide variety of numerical methods (finite element methods, nonconforming and mixed finite element methods, hybrid and mixed mimetic finite difference methods ...). Checking a minimal set of properties for a given numerical method suffices to prove that it belongs to the gradient schemes framework, and therefore that it is convergent on the different problems studied here. The study of the Stefan problem, the incompressible Stokes one and also the incompressible Navier-Stokes equations are presented in this thesis, where each one gets a convergence theorem set up with the gradient schemes framework. For Stokes and Navier-Stokes, we both provide the proof for the steady and the transient case dealing with some variational hypotheses which bring different convergence results. Finally, we also present four methods (Taylor-Hood, Crouzeix-Raviart, Marker-and-Cell, Hybrid Mixed Mimetic) for these two problems and we check that they enter in the gradient schemes framework

Den världsomfattande coronapandemin har påverkat mänskligheten på många plan och Sverige har tvingats möta en kris som krävt stora uppoffringar, både individuellt och kollektivt. I mars 2020 höll därför statsminister Stefan Löfven sitt första tal till nationen. I november samma år höll han det andra. Två tal till nationen under samma år och som bemöter samma kris är en historisk händelse som vi valt att analysera. Som kommunikationsstudenter ansåg vi det intressant att analysera retoriken och den retoriska situationen kring talen samt kriskommunikationen i relation till pandemin. Med tanke på coronapandemins aktualitet och den ovanliga talsituation som ett tal till nationen är, finns det ett allmän intresse för denna typ av studie och studien kommer behålla sitt värde för många år framöver. Studien har vi gjort med hjälp av en kvalitativ textanalys med fokus på retorisk ochsemiotisk analys och med hjälp av teorier rörande kriskommunikation och diskursanalys. Frågor vi ställt rör vilka skillnader som finns vad gäller retorik och semiotik mellan de båda talen, om det finns särskilda avsnitt i talen som har särskilda syften och i sådana fall vad dessa är, samt om det finns skillnader i Löfvens tonalitet och framställning. Utifrån dessa frågor kunde vigöra en retorisk analys och en semiotisk analys som i sin tur lade grunden för en analys kringkriskommunikationen och diskursen i samhället i mars respektive november 2020. Vi kom fram till att de retoriska och semiotiska skillnaderna mellan talen är få, men att det finns en viss skillnad i tonalitet och framställning vilket är ett resultat av den förändrade diskursen kring pandemin. / The corona virus has affected the world globally on many levels and together with the rest of theworld, Sweden has been forced into a crisis, which affected the citizens both individually and nationally. In Mars 2020, Swedish head of State Stefan Löfven spoke to the nation addressing thepandemic for the first time. In November the same year, he did it a second time. As this is a historical event we decided to analyze these two speeches regarding the corona virus. Since we are communication students we find it interesting to analyze the rhetoric as well as the semiotic situation regarding the speeches and the pandemic. Considering the timeliness of the coronapandemic and the unusual speech situation that a speech to the nation is, there is a public interest in this type of study and it will retain its value for many years to come. We made this study by using a qualitative text analysis, focusing on rhetoric andsemiotic analysis together with theories concerning crisis communication and discourse analysis. we have asked are if there are any rhetoric and semiotic differences between thetwo speeches, if there are several parts of the speeches with a specific purpose and in that casewhich they are and also if there are any differences regarding voice and formality. From these questions, we did a rhetorical as well as a semiotic analysis, which formed the base for further analysis regarding crisis communication and the discourses about the pandemic in March and November 2020. From this study we can see that the rhetorical and semiotic differences between thespeeches are few, but that there are some differences in voice and formality which are a result ofthe varying discourse in Sweden regarding the pandemic between March and November

[pt] O petróleo é constituído por uma cadeia de hidrocarbonetos, os quais se precipitam na forma de partículas sólidas de parafina, quando a sua temperatura cai abaixo de um patamar conhecido como TIAC (Temperatura Inicial de Aparecimento de Cristais). Essas partículas podem se depositar nas paredes internas dos dutos obstruindo o escoamento, podendo gerar prejuízos da ordem de milhões de dólares. Por esse motivo, a habilidade de previsão e controle da deposição de parafina em eventos futuros é de fundamental importância tanto para projetistas como operadores de tubulações. Visando lidar com esse problema, grande esforço vem sendo feito pela comunidade científica com o intuito de aperfeiçoar as metodologias para previsão do depósito de parafina. Frequentemente, a modelagem da difusão das espécies é realizada utilizando a Lei de Fick, válida para misturas binárias, apesar dos hidrocarbonetos presentes no petróleo formarem uma mistura multicomponente. O presente trabalho propõe avaliar o fluxo difusivo de massa das espécies utilizando o modelo Stefan-Maxwell, compatível com sistemas multicomponentes. Para determinar a evolução axial e temporal da espessura do depósito de parafina, o escoamento foi modelado como uma mistura líquido/sólido e equações de conservação de energia, massa, quantidade de movimento linear e continuidade das espécies são resolvidas, acopladas com o modelo termodinâmico de múltiplas soluções sólidas, para determinação da precipitação da parafina. As equações de conservação foram resolvidas utilizando o software de código livre OpenFOAM (marca registrada). Uma comparação das previsões obtidas com a modelagem de Fick e de Stefan-Maxwell com dados experimentais, mostrou que no início do processo de deposição, o impacto do modelo difusivo é desprezível. Porém, observou-se que a medida que o tempo passa, o modelo de Stefan Maxwell prevê um maior incremento da concentração das espécies mais pesadas no interior do depósito de parafina quando comparado com a previsão da modelagem de Fick. / [en] Petroleum is formed by a chain of hydrocarbons, which precipitates in the form of solid particles of paraffin, when its temperature drops below a threshold known as Wax Appearance Temperature (WAT). These particles can be deposited on the inner walls of the pipelines, obstructing the flow, which can generate losses in the order of several millions of dollars. For this reason, the ability to predict and control wax deposition in future events is of fundamental importance for both designers and operators of pipelines. In an attempt to deal with this problem, a great effort has been made by the scientific community aiming to improve wax deposition prediction methodologies. Often, the modeling of species diffusion is performed using Fick s law, valid for binary mixtures, although the hydrocarbons present in the oil form a multicomponent solution. The present work proposes to evaluate the species mass diffusive flux employing the Stefan-Maxwell model, compatible with multicomponent systems. To determine the axial and temporal evolution of the wax deposition thickness, the flow was modelled as a liquid/solid mixture and the conservation equations of energy, mass, linear momentum and species continuity were solved coupled with the thermodynamic model of multiple solid solutions, to determine the paraffin precipitation. The conservation equations were solved using the open-source software OpenFOAM (trademark). A comparison of the predictions obtained with the Fick and Stefan-Maxwell models with experimental data showed that at the beginning of the deposition process, the impact of diffusive model is negligible. However, it was observed that as time passes, the Stefan-Maxwell model predicts a greater increase in the concentration of heaviest species inside the wax deposit when compared to the prediction of Fick s law

Lors de la phase de rentrée atmosphérique d'une sonde spatiale, la paroi du corps est le siège de phénomènes physico-chimiques complexes. Nous nous intéressons dans cette thèse au cas où le matériau solide de l'objet de vol comporte plusieurs constituants s'ablatant de façon différentielle. En particulier, l'un de ces constituants subit un changement de phase donnant lieu à l'apparition d'une phase liquide. Nous sommes en présence de trois phases : solide, liquide et gaz. Les travaux effectués dans cette thèse correspondent au développement de méthodes numériques en 2D capables de modéliser les différentes interfaces en présence ainsi que l'évolution des fluides ou des matériaux séparés par celle-ci. L'enjeu principal de la thèse est de proposer des méthodes et des algorithmes de couplage pour l'écoulement diphasique, la thermique multimatériaux et les changements de phase (fusion et sublimation)

Stefan Zweig was an Austrian-Jewish author and intellectual who fled Austro-fascism and Nazi Germany, and took his own life in Brazil in early 1942. The resurgence of interest in Zweig’s life in the last few decades has introduced new methods of interpretation of his life as a refugee. But many scholars have not acknowledged Zweig’s relationships he formed with South American intellectuals while in exile there. Instead, the primary focus has been on his identity as a European, and his subsequent suicide. This paper will argue that Zweig’s identity as a refugee included a radical re-interpretation of history and perspective of the world outside of Europe, which had been previously based upon nationalistic and Euro-centric interpretations. Zweig’s exile was one of not only spatial displacement, but was also one of historical displacement, and the physical and political realities in Brazil contributed to this aspect of his life as a refugee.

This diploma thesis explores the concept of theatricality as developed by the Swiss theatrologist Stefan Hulfeld. The thesis aims at a presentation of Hulfeld's research which is based on examination of historical documents, his particular focus being the theatricality of the 18. century in Solothurn (Switzerland). In this thesis, his theory is compared to other theatricality theories developed by Rudolf Münz and Andreas Kotte. The more general aim of the presented work is to devise a notion of theatricality which is based on historical- theatrological exploration of historical documents.