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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.
1

Étude des biais observationnels induits par le caractère tridimensionnel des atmosphères d’exoplanètes / Impact of three-dimensional aspects of exoplanet atmospheres on observations and retrievals

Caldas, Anthony 17 December 2018 (has links)
Nous cherchons à mettre en évidence l'influence des hétérogénéités de température, de structure ou de composition des atmosphères sur leurs observations. Dans le années à venir, de plus en plus d'appareils vont permettre l'observation par transmission des atmosphères d'exoplanètes. Toutefois, les outils numériques permettant de contraindre ces dernières reposent sur des modèles simples à une dimension. Ils supposent en effet des atmosphères ne possédant qu'une structure verticale (le climat est le même en tout point de la surface, la composition ou la température n'évolue qu'avec l'altitude). Cette approche a le mérite de permettre des calculs rapides et de contraindre les paramètres globaux de l'atmosphère avec des temps raisonnables. Ceci ne serait pas possible en l'état avec une modélisation en 3 dimensions des atmosphères, même si ce serait beaucoup plus réaliste. Ce que nous cherchons à mettre en évidence, ce sont les limites des techniques actuelles d'inversion et donc, de caractérisation des atmosphères qui seront observées. Pour cela, il fallait mettre au point un logiciel capable de résoudre le transfert radiatif au sein d'une atmosphère en 3 dimensions (et non plus 1 seul). Une fois le logiciel terminé, nous avons éprouvé l'algorithme de traitement du signal TauREx en comparant les résultats qu'il proposait à des simulations atmosphériques parfaitement contrôlées. Nous nous sommes tout principalement arrêté sur les biais découlant d'hétérogénéités de température en simulant des atmosphères avec un fort contraste jour/nuit. Ceci nous a permis de caractériser les biais découlant de ces types d'hétérogénéités, de les quantifier et de mettre l'accent sur un biais jusqu'ici très sous-estimé par la communauté, à savoir celui découlant des hétérogénéités le long de la ligne de visée. Nous avons appuyé nos propos et concentré nos efforts sur l'interprétation de l'inversion d'une simulation complexe de l'atmosphère de GJ 1214 b. La reconstitution de la chaine observationnelle : GCM (LMD), Pytmosph3R (LAB) et TauREx (UCL) ouvre les portes d'un vaste panel d'études envisageables, et notamment tout ce qui va concerner l'identification et la caractérisation des biais systématiques qui incomberont les observations à venir. / Transmission spectroscopy provides us with information on the atmospheric properties at the limb, which is often intuitively assumed to be a narrow annulus aound ther planet. Consequently, the few recent studies on the effect of atmospheric horizontal heterogeneities on transmission spectra have used approaches sensitive to variations along the limb only. Here we demonstrate that the region probed in transmission – the limb – actually extends significantly toward the day and night sides of the planet. Consequently we show that thestrong day-night thermal and compositional gradients expected on synchronous exoplanets create sufficient heterogeneities across the limb to result in important systematic effects on the spectrum and bias its interpretation. To quantify these effects, we developed a 3D radiative transfer model able to generate transmission spectra of atmospheres based on 3D atmospheric structures, whether they come from a Global Climate Model or more parametrized models. We first apply this tool to a simulation of the atmosphere of GJ 1214 b toproduce synethic JWST observations and show that producing a spectrum using only atmospheric columns at the terminator results in errors greater than expected noise. This demonstrates the necessity of a real 3D approach to model data for such precise observatories.Second, we investigate how day-night temperature gradients cause a systematic bias in retrieval analysis performed with 1D forward models. For that purpose we synthesize a large set of forward spectra for prototypical HD209458 b and GJ 1214 b type planets varying the temperatures of the day and night sides as well as the width of the transition region. We then perform typical retrievalanalyses and compare the retrieved parameters to the ground truth of the input model. This study reveals systematic biases on the retrieved temperature (found to be higher than the terminator temperature) and absorber abundances. This is due to the fact that the hotter dayside is more extended vertically and screens the nightside—a result of the nonlinear properties of atmospheric transmission.These biases will be difficult to detect as the 1D profiles used in the retrieval procedure are found to provide an excellent match to theobserved spectra based on standard fitting criteria (chi2, posterior distributions). This fact needs to be kept in mind when interpretingcurrent and future data.
2

Trapistas no Brasil / Trappist in Brazil

Silva, José Pereira da 03 October 2014 (has links)
Os Trapistas no Brasil é o objeto do nosso trabalho. A primeira experiência trapista no Brasil ocorreu no início do século XX no Vale do Paraíba Paulista. Monges Trapistas franceses deram início ao Mosteiro Nossa Senhora de Maristela, na cidade de Tremembé, estado de São Paulo. Passou a ser também a primeira Trapa da América do Sul. Com esse mosteiro, houve o início da vida e da tradição monástica cisterciense no Brasil. No Vale do Paraíba, revolucionaram a agricultura com modernas técnicas agrícolas, principalmente na rizicultura, e prestaram também relevantes serviços no campo socioeclesial. Posteriormente, com o regresso destes para Europa, houve, em 1977, a fundação do Mosteiro Trapista Nossa Senhora do Mundo, no estado do Paraná. A relação entre o primeiro Mosteiro Trapista no Brasil, fundado no início do século XX, e o segundo Mosteiro, Nossa Senhora do Novo Mundo, iniciado em 1977, mostra que o passado e presente caminham nessa relação: a ponte entre história e memória. O passado e a sua relação com ele são elementos centrais da identidade da Ordem Cisterciense da Estrita Observância / The Trappists in Brazil is the aim o four assignment. The first Trappist experience in Brazil happened in the beginning of the XX century in the region of Paraíba Valley. French Trappist monks started the Monastery of Our Lady Maristela, in Tremembé city state of São Paulo. It also became the first Trapa of South America. With this monastery, we had the beginning of Cistercian monastic life and tradition in Brazil. In the region of Paraíba Valley, modern agricultural techniques were revolutionized, especially in rice growing; they also provided relevant relevant services in the church social field . Later, with the return of these to Europe in 1977, we had the foundation of the Trappist Monastery of Our Lady of the New World, in the state of Paraná. The relationship between the first Trappist Monastery in Brazil, founded in the early twentieth century, and the second Trappist Monastery of Our Lady of the New World, which started in 1977, shows that the past and present walk together, the bridge between history and memory. The past and its relationship with it are core elements to the identity of the Cistercian Order of Strict Observance
3

Trapistas no Brasil / Trappist in Brazil

José Pereira da Silva 03 October 2014 (has links)
Os Trapistas no Brasil é o objeto do nosso trabalho. A primeira experiência trapista no Brasil ocorreu no início do século XX no Vale do Paraíba Paulista. Monges Trapistas franceses deram início ao Mosteiro Nossa Senhora de Maristela, na cidade de Tremembé, estado de São Paulo. Passou a ser também a primeira Trapa da América do Sul. Com esse mosteiro, houve o início da vida e da tradição monástica cisterciense no Brasil. No Vale do Paraíba, revolucionaram a agricultura com modernas técnicas agrícolas, principalmente na rizicultura, e prestaram também relevantes serviços no campo socioeclesial. Posteriormente, com o regresso destes para Europa, houve, em 1977, a fundação do Mosteiro Trapista Nossa Senhora do Mundo, no estado do Paraná. A relação entre o primeiro Mosteiro Trapista no Brasil, fundado no início do século XX, e o segundo Mosteiro, Nossa Senhora do Novo Mundo, iniciado em 1977, mostra que o passado e presente caminham nessa relação: a ponte entre história e memória. O passado e a sua relação com ele são elementos centrais da identidade da Ordem Cisterciense da Estrita Observância / The Trappists in Brazil is the aim o four assignment. The first Trappist experience in Brazil happened in the beginning of the XX century in the region of Paraíba Valley. French Trappist monks started the Monastery of Our Lady Maristela, in Tremembé city state of São Paulo. It also became the first Trapa of South America. With this monastery, we had the beginning of Cistercian monastic life and tradition in Brazil. In the region of Paraíba Valley, modern agricultural techniques were revolutionized, especially in rice growing; they also provided relevant relevant services in the church social field . Later, with the return of these to Europe in 1977, we had the foundation of the Trappist Monastery of Our Lady of the New World, in the state of Paraná. The relationship between the first Trappist Monastery in Brazil, founded in the early twentieth century, and the second Trappist Monastery of Our Lady of the New World, which started in 1977, shows that the past and present walk together, the bridge between history and memory. The past and its relationship with it are core elements to the identity of the Cistercian Order of Strict Observance
4

Transmission spectroscopy of TRAPPIST-1d with the new Palomar/WIRC+Spec instrument : a Karhunen-Loève transform based approach to extracting spectrophotometry

Chan, Jonathan 12 1900 (has links)
Le système TRAPPIST-1 offre une opportunité sans précédent de caractériser les premières planètes potentiellement habitables en dehors de notre système solaire. Dans ce mémoire est décrit le développement d’un pipeline de réduction de données personnalisé pour le mode WIRC+Spec de la caméra infrarouge à grand champ récemment mise à niveau à l’observatoire Palomar. Nous introduisons une nouvelle approche d’ajustement de la fonction d’étalement du point basée sur la transformation de Karhunen-Loève pour extraire des courbes de lumière photométrique et spectroscopique de sources de forme irrégulière, que nous appliquons aux observations de l’exoplanète TRAPPIST-1d pour mesurer ses spectres de transmission dans les bandes J (1.1 à 1.4 µm) et Ks (1.95 à 2.35 µm). Un guide détaillé est présenté pour l’implémentation d’un calcul de profils de température incluant l’équilibre radiatif et convectif pour une modélisation atmosphérique efficace et précise. En comparant une multitude de scénarios atmosphériques aux observations de TRAPPIST-1d, nous obtenons des contraintes sur la composition et la structure de son atmosphère, excluant les scénarios sans nuages avec des métallicités inférieures à 300 fois la valeur solaire à 3σ. / The TRAPPIST-1 system provides an unprecedented opportunity to characterize the first potentially habitable planets outside our solar system. In this work we describe the development of a custom data reduction pipeline for the WIRC+Spec mode of the recently upgraded Wide Field Infrared Camera instrument on Palomar Observatory. We introduce a novel, Karhunen-Loève transform based approach to extract photometric and spectroscopic light curves from irregularly shaped sources, which we apply to observations of the TRAPPIST-1d exoplanet to measure the J band (1.1 to 1.4 µm) and Ks band (1.95 to 2.35 µm) transmission spectra. We also present a detailed guide into the implementation of a self-consistent, radiative-convective temperature structure calculation for efficient and accurate atmospheric modelling. Comparing a host of atmospheric scenarios to the observations of TRAPPIST-1d to date, we constrain its atmosphere, ruling out cloud-free atmospheres with metallicities lower than 300 times the solar value at 3σ confidence.
5

Israeli military fiction: a narrative in transformation

Rubinstein, Keren Tova Unknown Date (has links) (PDF)
The current study investigates changing attitudes to militarism within Israeli society since the tumultuous decades following 1948. Events leading to the current state of Israeli society will be traced in order to illustrate the way in which change occurs. The shifts in Israeli history and society during these decades will be examined alongside developments in Israeli literature. Accordingly, eight works of fiction have been selected to lie at the heart of the study. These works, all of which centre around the Israeli military experience, convey an erosion of personal, national, and ideological certainties. The analysis of these works demands three areas of exploration: the depiction of the soldier in the civilian setting, the depiction of the soldier as he interacts with other soldiers in the military sphere, and ‘post-Zionist’ military fiction produced in recent decades. These three areas of exploration entail an interrogation of gender, nationalism, and ‘post-Zionism’ in contemporary Israel. The works examined in the third chapter contain commentary not only upon the social reality of their authors, but also upon the way in which Israeli literature engages with the issues that inform its existence. (For complete abstract open document)

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