Este trabalho tem como propósito, investigar a validade da lei de Hess-Murray, através da experimentação numérica, aplicando o método do Design Construtal associado ao método de otimização da busca exaustiva, no escoamento interno em estruturas em forma de T com seção circular. Variação do número de Reynolds, escoamento de fluidos newtonianos e não newtonianos, estrutura em forma de T com paredes impermeáveis e permeáveis, foram as principais características avaliadas para confrontar a lei de Hess-Murray. O estudo proposto assume escoamento tridimensional, laminar, incompressível, regime permanente e propriedades fluidodinâmicas constantes, sendo o regime de escoamento governado pelo número de Reynolds (Re). O objetivo principal consiste em determinar as configurações ótimas que facilitem o escoamento de fluido ou minimizem as resistências ao escoamento, quando a área ocupada pelos dutos (A) e o volume ocupado pelos dutos (V) são mantidos constantes, variando-se as razões de diâmetros (aD) e comprimentos (aL). As equações de conservação de massa e quantidade de movimento, foram resolvidas através do método de volumes finitos. A geometria foi discretizada através de uma malha tridimensional composta por aproximadamente 1.950.000 elementos. Como resultados, obteve-se as geometrias ótimas que apresentaram resistências ao escoamento até 30 vezes menor do que as demais configurações. Além disso, foi possível verificar que a lei de Hess-Murray nem sempre é válida, visto que o sistema adapta sua geometria ótima para cada condição de escoamento, a fim de proporcionar a melhor arquitetura de escoamento para atender ao objetivo de minimizar as resistências ao escoamento em acordo com a Lei Construtal. Esta dissertação avançou no presente estado da arte, pois desenvolveu um modelo tridimensional sem simplificações, aplicado ao sistema de escoamento de fluidos em estrutura em forma de T utilizando o método do Design Construtal, validando os resultados analíticos apresentados na bibliografia e apresentando novas referências que permitem ampliar a complexidade dos sistemas de escoamento bem como a implementação de métodos de otimização mais avançados. / This work investigates, through the numerical experimentation together with the Construtal Design method, the Hess-Murray Law in the internal flow in T-shaped structures with a circular section for the laminar flow of Newtonian and non-Newtonian fluids with impermeable and permeable walls, determining the optimal configurations that facilitate fluid flow or minimize flow resistance. The geometric global constants, the volume occupied by the ducts (V) and the area occupied by the ducts (A), delimit the space occupied by the T-shaped structure and the degrees of freedom, the ratio between the diameter of the parent duct and daughter (aD) and the ratio between parent duct length and daughter (aL), are the main geometric parameters to be evaluated. The proposed study is assumed three-dimensional, laminar, incompressible, permanent and constant fluidodynamic properties being the flow regime governed by Reynolds number (Re). Construtal Design method, associated with the exhaustive search, was used to determine the global geometric constants, degrees of freedom and objective function in the geometric evaluation of the system. The numerical solution of the mass conservation and momentum equations is solved based on the finite volume method. The geometries and mesh of the computational domain was discretized through a three-dimensional composed of approximately 1,950,000 elements. The results show that the optimal geometries that presented resistance to the flow up to 30 times smaller than the other configurations. In addition, it was possible to verify that the Hess-Murray Law is not always valid, since the system adapts its optimal geometry to each flow condition, in order to provide a better flow architecture to meet the objective of minimizing resistance to flow in agreement with the Constructal Law. This work advanced in the present state of the art, since it developed a three-dimensional model without simplifications, applied to the fluid flow system in T-shaped structure using the Construtal Design method, validating the analytical results presented in the bibliography and presenting new references that allow increase the complexity of flow systems as well as the implementation of more advanced optimization methods.

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Die Arbeit beschäftigt sich mit der Quelle hochenergetischer Gammastrahlung HESS J1745-290, welche in Richtung des galaktischen Zentrums liegt und präsentiert die Analyse eines Datensatzes, der von den H.E.S.S. Teleskopen zwischen 2004 und 2014 aufgezeichnet wurde. Ziel der Untersuchung war es, eine zeitliche Variabilität des beobachteten Flusses festzustellen. Die Frage ob der Fluss von HESS J1745-290 variables Verhalten zeigt stellt sich, da sich die Quelle in der gleichen Richtung wie das supermassive schwarze Loch Sgr A* befindet, aus dessen Umgebung bereits variable Strahlung in verschiedenen Frequenzbereichen detektiert wurde. Die Beobachtung einer Variabilität des hochenergetischen Gammastrahlenflusses von HESS J1745-290 würde die Hypothese eines Zusammenhangs zwischen diesem Objekt und Sgr A* stützen, welche bis dato nicht bestätigt werden konnte. Die Suche nach Variabilität wurde für verschiedene Zeitskalen von Minuten bis hin zu Jahren durchgeführt, wobei Hinweise für Variabilität in verschiedenen statistischen Tests gefunden wurden. Die Suche konzentriert sich auf Variabilität ohne periodischen Charakter sowie auf Periodizität. Es wurden Hinweise auf eine Periode von 110 Tagen bei einem Signifikanzniveau von 4.1σ gefunden und auch der Fit einer H.E.S.S. Lichtkurve, die von 2004–2014 reicht, zeigt Variabilität bei einem Signifikanzniveau von 6.1σ, welches sich nach Anwendung eines systematischen Fehlers von 10% auf 4.5σ reduziert. Auch Anzeichen für Variabilität auf einer Zeitskala von Minuten wurden gefunden. Diese Variabilität auf einer Zeitskala von Minuten zeigt quasi-periodischen Charakter, ähnlich derer, welche während Infrarot und Röntgenbeobachtungen von Sgr A* festgestellt wurde. Die Möglichkeit einer Verbindung zwischen HESS J1745-290 und Sgr A* und insbesondere auch die Fragestellung, ob die hier präsentierten Ergebnisse als erster Hinweis auf solch einen Zusammenhang gewertet werden können, werden Thema der Diskussion am Ende der Arbeit sein. / A detailed study on the very-high-energy (VHE) γ-ray source HESS J1745-290 in direction of the Galactic Center using 10 years of data from the H.E.S.S. array of Cherenkov telescopes from 2004 to 2014 with the objective to search for variability of the γ-ray flux of this object is presented. The question if HESS J1745-290 shows variability is of special interest, since the source is located at the same direction as the super-massive black hole Sgr A*. From the vicinity of this black hole variable radiation has been reported for different wavelength bands. The detection of a variability of the VHE γ-ray flux of HESS J1745-290 would favor the hypothesis of a connection of this object and Sgr A* which could not be confirmed so far. The search for variability was performed for different timescales from minutes to years and indeed revealed evidence for variability in different statistical tests which will be discussed in detail together with systematic cross-checks. The study focuses on both variability with and without periodic character. While there is evidence for a long-term flux modulation with a period of 110 d at the 4.1σ significance level, the fit of a H.E.S.S. run-wise light curve from 2004–2014 shows variability at the 6.1σ level, which reduces to 4.5σ after adding a 10% systematic error to each flux measurement. Also signs of variability at a timescale of minutes were found at the 3.1σ level. This tentative VHE short-term variability also shows quasi-periodic behavior as it was reported during infrared and X-ray observations of Sgr A*. Such a tentative long-term flux modulation with a period of 110 d has previously also been reported for the radio band. Due to the similarity of time structure of the variability, which is reported for HESS J1745-290 in this thesis to observations of Sgr A* at other wavelength bands, the thesis will close with the discussion if these results can be considered to be first evidence for a link between HESS J1745-290 and Sgr A*.

Diese Arbeit beschreibt die Identifikation der bisher unidentifizierten TeV Gammastrahlungsquelle, HESS J1303-631 als Pulsarwind-Nebel, angetrieben von dem Pulsar PSR J1301-6305. Dieses Ergebnis wird durch den Nachweis von energieabhängiger Morphologie in den vom High Energy Stereoscopic System (H.E.S.S.) genommenen Daten und durch die Detektion eines neuen Röntgen-Pulsarwind-Nebels in XMM-Newton Daten erreicht. Zudem wird eine obere Schranke auf den Fluss von Radiostrahlung aus Beobachtungen mit dem Parkes Radioteleskop bei 4.48 GHz abgeleitet. Diese Ergebnisse können in einem leptonischen Modell des Pulsarwind-Nebels verstanden werden, wo Elektronen und Positronen in der Nähe des Termination Shocks des Pulsarwindes auf ultrarelativistische Energien beschleunigt werden. Diese Leptonen bilden einen ausgedehnten Pulsarwind-Nebel, der auf Grund des inversen Compton-Effekts und Synchrotronstrahlung TeV Gammastrahlung beziehungsweise Röntgen- und Radiostrahlung erzeugt. Da nur eine obere Grenze auf den Radiofluss abgeleitet wurde, erfolgte die Modellierung im Rahmen eines einfachen ``one zone models'''', wo angenommen wird, dass die Radio-, Röntgen- und Gammastrahlung alle von derselben Leptonenpopulation erzeugt werden. Das Modell wird aber trotzdem von den Daten schon eingeschränkt und liefert ein schwaches Magnetfeld von ungef 0.9 Microgauss. Diese Magnetfeldstärke ist überraschend niedrig, da in ähnlichen Systemen die Magnetfeldstärken eher bei 10 Microgauss liegen. Andererseits passt das Ergebnis gut zu dem sehr niedrigen Synchrotronstrahlungsfluss. Ein derart schwaches Magnetfeld wird im theoretischen Szenario eines ausgedehnten, beziehungsweise entwickelten Pulsarwind-Nebels erklärt. / This work represents the identification of the very high energy, E > 100 GeV (VHE), Gamma-ray source HESS J1303-631 as a pulsar wind nebula (PWN) powered by the pulsar PSR J1301-6305. This is achieved through the detection of energy dependent morphology in the High Energy Stereoscopic System (H.E.S.S.) data, the detection of a new X-ray PWN in archival XMM-Newton X-ray observations, as well as multi-wavelength modeling of the source and its energetics. An upper limit on the radio synchrotron flux is obtained from observations made by the Parkes telescope at 4.48 GHz. The combined Gamma-ray, X-ray and radio measurements are used to constrain a leptonic emission model, where strong winds of relativistic electrons and positrons from the pulsar power the acceleration of particles to ultrarelativistic energies at the wind termination shock region, and these shock accelerated leptons then form a nebula which emits in the X-ray and radio bands via synchrotron emission in the ambient magnetic field and Gamma-rays through the inverse Compton mechanism. One surprising result of this analysis is the anomalously low magnetic field derived for the PWN. Typical values for PWNe are on the order of 10 microgauss. For this source, however, the low synchrotron levels predict an average magnetic field of approximately 0.9 microgauss. The low magnetic field is explained in the scenario of an expanded/evolved PWN.

In dieser Arbeit wird eine Analyse der TeV gamma-Strahlung in der Region um den galaktischen Sternhaufen Westerlund 2 präsentiert. Der dazu analysierte Datensatz beruht auf Observationen mit den Cherenkov Teleskopen des High Energy Stereoscopic System (H.E.S.S.) Experiments und umfasst ~80h Beobachtungszeit. Für die Datenanalyse wird die open-source Software gammapy benutzt, um morphologische und spektrale Modelle der gamma-Emission zu erstellen. Zur Modellauswahl wird das Akaike-Informationskriterium angewandt. Die Ergebisse der Analysen werden weiter mit Daten aus anderen Wellenlängenbereichen kombiniert, um Schlüsse auf den möglichen Ursprung der TeV-Signale zu ziehen. Neben Hinweisen auf eine diffuse gamma-Emission und mehrerer Hotspots um Westerlund 2 ist die Detektion von drei ausgedehnten gamma-Strahlungsquellen das Hauptergebnis der dargelegten Analysen. Zusätzlich zu den bekannten Quellen HESS J1023-575 und HESS J1026-582 wird die Detektion einer neuen, elliptischen Quelle südöstlich von HESS J1023-575 präsentiert. Diese neue Quelle, als ''TeV jet cloud'' bezeichnet, zeigt räumliche Übereinstimmung mit länglichen Gaswolken, die in CO und HI Radio Daten gefunden wurden. Der Ursprung dieser Gaswolken könnte der Jet eines Mikroquasars oder einer anisotropischen Supernova sein. Eine weitere räumliche Übereinstimmung zeigt HESS J1023-575 mit einer sphärischen Gaswolke, die ihren Ursprung in einer Supernova haben könnte. HESS J1023-575 und die Gaswolken sind dabei symmetrisch zur Hauptachse der neuen elliptischen gamma-Quelle ausgerichtet, was eine Verbindung der Komponenten in einem hadronischen Emissionszenario nahelegt. Aus den Wolkenmassen und der gamma-Emission ergibt sich eine Verstärkung der kosmischen Strahlung in der Region, was auf aktive Teilchenbeschleunigung hindeutet. Sollte ein Mikroquasar in der Region gefunden werden, könnte dieses die erste Detektion eines galaktischen hochenergetischen Jets mit Cherenkov Teleskopen sein. / This work presents a study of the TeV gamma-ray emission in the region of the stellar cluster Westerlund 2. The main dataset analysed in this work was obtained with the imaging atmospheric Cherenkov telescopes of the High Energy Stereoscopic System (H.E.S.S.), comprising a total of ~80h of observation time. The high-level analysis of the dataset is performed with the open-source software gammapy to produce extensive spectral and spatial models for the observed emission. The best-fitting models are determined by using the Akaike information criterion. The results are combined with findings from other wavelengths to probe different emission scenarios. Besides hints of a diffuse emission and the detection of multiple hotspots, the presented studies yield three extended gamma-ray sources around Westerlund 2. Besides the known sources HESS J1026-582 and HESS J1023-575, an elongated elliptical gamma-ray source referred to as ''TeV jet cloud'' is newly found to the south east of HESS J1023-575. It shows a spatial coincidence with elongated cloud structures seen in CO and HI radio data which may originate from a high energy jet of a mircroquasar or an anisotropic supernova. Another spatial agreement is seen between HESS J1023-575 and a spherical shell of hydrogen gas which may be the remains of an old supernova remnant. HESS J1023-575 and the gas cloud structures symmetrically align along the major axis of the TeV jet cloud. This suggests a connection of these components in a hadronic emission scenario. Combining the masses of the clouds with the measured gamma-ray flux yields a high cosmic ray enhancement factor, suggesting active particle acceleration in the region. If a microquasar would be found around the best-fit position of HESS J1023-575, this could be the first detection of a galactic high energy jet at TeV energies with Cherenkov telescopes.

Le télescope H.E.S.S. (High Energy Stereoscopic System), implanté en Namibie, est actuellement le plus efficace pour l'observation de sources de rayons gamma de très haute énergie. Constitué de 4 télescopes de grand diamètre fonctionnant en stéréoscopie, il permet une cartographie sans précédent du plan de la Galaxie à ces longueurs d'onde extrêmes. L'expérience HESS a mis en évidence la présence de particules chargées d'énergie supérieure à une centaine de TeV dans plusieurs vestiges de supernova, lieux probables d'accélération de particules dans la Galaxie, sans toutefois pouvoir conclure sur la nature hadronique ou leptonique des particules. Cette thèse présente une démarche observationnelle alternative visant à mettre en évidence l'accélération de hadrons par onde de choc dans les vestiges de supernova. Une recherche de vestiges associés à des nuages moléculaires a été menée avec les sources déjà détectées par H.E.S.S. et dans l'ensemble des observations réalisées. L'analyse et l'interprétation de trois sources de rayons gamma sont décrites. La première est la nouvelle source découverte par H.E.S.S. dans la constellation de Monoceros. Je présente ensuite l'analyse des nouvelles observations réalisées en direction de la source non identifiée HESS J1745-303. Enfin l'analyse multi-longueurs d'onde de la nouvelle source de rayons gamma coïncidente avec le vestige de supernova CTB37A est décrite. Je développe les possibles interprétations de cette émission de rayons gamma. Un apport à la construction de la seconde phase de l'expérience H.E.S.S. est présentée. Cette deuxième phase consiste en l'adjonction d'un cinquième télescope de 28 mètres de diamètre au centre du système existant. J'ai pris en charge les tests et la sélection des 6000 puces constituant le système d'échantillonnage de la caméra qui équipera ce télescope.

This study examines teachers' approach to controversial topics, within the subject of civics and social sciences in Swedish upper secondary school. The aim of the study is to describe and problematize the approaches chosen by teachers when controversial topics are brought up in the classroom. To achieve this, the study will examine the following questions: What do teachers consider as controversial topics? How do teachers handle situations where controversial topics arise in the classroom? Why do teachers believe controversial topics are important in education? To answer these questions, several qualitative interviews were executed. The results show that there are several topics in civics and social sciences that may strike one as being controversial. Examples of such topics are questions regarding immigration, minorities, feminism, gender, and ethnicity. In summary, the results show that teachers aspire to let controversial issues be a part of their subject, and that they see benefits with this. However, the teachers' attitudes toward their mission differ, which can also be said about their perspective on what could be the definition of “controversial topics”. The reasonings presented by teachers in this study, as to why they find these topics important, can be divided into two sections. Firstly, such topics matter to students and are engaging. Secondly, it is relevant to the subject of civics and social studies, as well as the curriculum and it’s mission to foster democracy.

Kabīr stands as one of the most, if not the most, influential nirguṇbhakti poet of the so-called Sant movement in northern India during the 15th century. Even though his fame is far and widely spread, there is no extensive historical evidence regarding his own life. The understanding one might have surrounding Kabīr is mostly inspired by his poems, or following the information which is available through the rich traditions regarding Kabīr, mostly authored by his followers in the Kabīr Panth. His critical view on high caste society, and rough rhetoric regarding the institutionalized religious traditions of his era, made him a victim of hate and violence during his lifetime. After his death, this rough rhetoric and critical view, ignited a full on dispute between Hindus and Muslims on the subject of which group he belonged to. The teachings of Kabīr has not only sparked an interest in the field of academia but also in movies, literature and theater alike. The latter is the main subject of interest for this paper. The renowned Indian writer Bhisham Sahni has during his life been recognized as one of the most influential writers in the so-called Nayī Kahānī movement, which sprung from a new found vision of the future after Indian independence 1947. Sahnis is mostly famous for his novels and short stories, with such titles as Tamas and Amṛtsar ā gayā hai. But in this paper we shall instead take a closer look into his play Kabirā khaḍā bazār meṃ and how Kabīr is portrayed and understood by Sahni, as well as, if and how Sahni’s Kabīr can be understood within a comparative analysis with how he is portrayed in the introduction to Rabindranath Tagore’s One hundred poems of Kabir by Evelyn Underhill and in Linda Hess’s The Bījak of Kabīr.

L'experience H.E.S.S. (High Energy Stereoscopic System) est constiture de quatre imageurs Cherenkov atmospheriques dedies a l'observation de sources astrophysiques de l'hemisphere austral emettant des photons au-dela de 100 GeV. Cette these presente le fonctionnement de cet instrument ainsi que toute la chaine d'analyse associee. Les methodes d'etalonnage du systeme sont detaillees et les erreurs systematiques sur l'amplitude des images sont estimees. Ensuite, une methode d'analyse des donnees, basee sur un modele semi-analytique de developpement des gerbes electromagnetiques dans l'atmosphere, est expliquee. Des methodes de reconstruction du spectre en energie et de la morphologie des sources de gamma haute energie sont presentees puis appliquees a la Nebuleuse du Crabe. Les erreurs systematiques associees a l'analyse spectrale sont estimees. Cette chaine d'analyse est ensuite utilisee pour etudier l'emission du Centre Galactique au-dela de 100 GeV. Les differentes observations menees en 2003 et 2004 ont mis en evidence un signal dont l'origine n'est pas encore connue. Le spectre, la variabilite et la morphologie de la source sont etudies. De nombreux candidats sont proposes, en particulier le trou noir supermassif Sgr A* situe au centre dynamique de la Voie Lactee, le reste de supernova Sgr A Est ou des interactions de particules accelerees sur le milieu dense de cette region. Dans cette these, le signal est interprete comme provenant de l'annihilation de particules de matiere noire non baryonique (neutralinos ou bosons de Kaluza-Klein) dans un halo dense situe au Centre Galactique. Cette analyse indique que le signal ne provient pas exclusivement d'annihilation de matiere noire dans le cadre des modeles etudies, et que la composante dominante serait donc de nature astrophysique.