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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.
241

Estudo da estabilidade de anéis em exoplanetas /

Pinheiro, Tiago Francisco Lins Leal. January 2019 (has links)
Orientador: Rafael Sfair de Oliveira / Resumo: A estrela PDS110 (HD290380) com idade aproximada de 10 milhões de anos, apresentou dois eclipses ocorridos em 2008 e 2011, com duração de 25 dias e queda de aproximadamente 26 % na luminosidade da estrela. Outra estrela J1407 (1SWASP J140747.93-39454.6) apresentou uma complexa série de eclipses com 56 dias de duração. As hipóteses dadas a esses dois eventos foram a passagem da borda de um disco planetário ou um disco circunstelar de uma anã marrom. Neste trabalho foi analisada a natureza desses possíveis sistemas de anéis ao redor de um exoplaneta gigantesco não observado, que teria ocultado essas estrelas. Para estudar o sistema PDS110b, devido ao grande número de variáveis envolvidas ainda desconhecidas neste problema como, por exemplo, massa e excentricidade do planeta, inclinação e extensão do disco, foram criados diversos modelos numéricos considerando a interação gravitacional entre a estrela, o planeta e a partícula do anel. Desta forma foi possível refinar os intervalos dos parâmetros predeterminados através dos dados observacionais, que seriam compatíveis com o eclipse observado. Os resultados indicam que provavelmente os eclipses teriam ocorrido por um planeta com massa entre 50 e 70 MJup, em uma orbita quase circular (ePDS110b < 0,05) e o semieixo maior de 2 ua. O sistema de anel ao redor do PDS110b, teria uma extensão radial de ~ 0,2 ua, significativamente maior que o raio de Roche do planeta e um forte indicio da presença de satélites. Ao analisar o sistema de an... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The star PDS110 (HD290380) is approximately 10 millions years old, underwent two eclipses observed in 2008 and 2011 in the surrounding 25 days with a depth 26 % in the star's luminosity. Other star J1407 (1SWASP J140747.93-39454.6) underwent a complex series of eclipses that lasted 56 days. The hypothesis could explain those events are the transit of the edge one disc circumplanetary or circumstelar (brown dwarf). In this work, we analyzed the nature of a possible ring system around these giant exoplanets would have occulted the star. To study the PDS110b system, in the reason to the large number of unknown variable involved in this problem like: mass and the eccentricity of the PDS110b, inclination and size of the disc, we created a several numerical models considering the only gravitational interactions between the star, the planet and the particle of the ring. We managed to restrict the interval of the parameters predetermined by the observational data. The best models indicate a planet's mass between [50 - 70] MJup, in the quasi circular orbit (ePDS110b < 0,05) and semi major axis of 2 ua. The ring system around the PDS110b, probably has ~ 0,2 ua of radial extension. To analyze the ring system around J1407b, after excluded some proposals of the eclipsing body to be a secundary star, the studies propose an extensive ring system with radius of 0,6 ua, formed by at least 37 different rings and one possible exomoon with mass proportional to Earth, located at the gap observed ... (Complete abstract click electronic access below) / Mestre
242

Elaboração de um modelo para formação planetária dentro do código magneto hidrodinâmico FARGO3D / Elaboration of a model for planetary formation in the hydrodynamic magneto code FARGO3D

Paula, Luiz Alberto de 26 September 2018 (has links)
De acordo com o modelo sequencial de acreção, os planetas gigantes se formam através de um núcleo sólido a partir da captura de planetesimais. Esse núcleo, atingindo uma determinada massa, é capaz de capturar o gás residual do disco protoplanetário que constituirá o seu envelope, formando, então, um planeta gigante (Mizuno, 1980; Pollack et al., 1996). A parte crtica desse cenário está no ajuste dos tempos de formação do núcleo sólido, de captura do gás e dos processos de migração planetária com o tempo de vida do disco (Mordasini et al., 2010). Resultados numéricos mostram que o tempo necessário para a formação de um planeta gigante é muito alto em relação ao tempo de vida do disco, e, que a migração planetária pode ser muito rápida, levando os planetas a carem na estrela antes de sua completa formação. Em geral, os trabalhos sobre formação planetária tratam a migração do planeta utilizando prescrições analíticas (Fortier et al., 2013). No entanto, diversos efeitos associados à termodinâmica do disco de gás fazem com que esses modelos analíticos sejam limitados para lidar com a migração planetária (Paardekooper et al., 2010). De fato, para lidar com a migração planetária de tipo I, esses resultados analíticos se utilizam de discos de gás fisicamente simples e da linearização das equações da hidrodinâmica (Meyer-Vernet e Sicardy, 1987; Tanaka et al., 2002). Para a migração de tipo II, a situação é ainda mais complicada, já que a alta massa do planeta cria um gap em torno da órbita planetária, que impõe uma quebra da linearidade, impossibilitando a obtenção de uma prescrição analtica (Bryden e Lin, 1999). Assim, os resultados numéricos obtidos a partir de simuladores hidrodinâmicos, como o FARGO3D (Masset, 2000; Bentez-Llambay e Masset, 2016), ZEUS (Stone e Norman, 1992), PLUTO (Mignone et al., 2012), entre outros, são essenciais para uma análise mais robusta dos processos de migração planetária dentro de uma gama maior de condições fsicas para o disco de gás. No entanto, os simuladores hidrodinâmicos que tratam da interação do planeta com o disco de gás, em geral, não possuem um modelo para formação planetária. Em alguns deles, modelos para acreção de gás são construdos com base no regime de runaway dessa acreção (Kley, 1999). Todavia, a acreção de sólidos e a acreção de gás para planetas de baixa massa, na maior parte dos casos, não são levadas em consideração. Boa parte disso se deve ao fato de os modelos de formação planetária usarem simulações N-corpos, que, aliados ao código hidrodinâmico, seriam altamente custosos computacionalmente. Assim, torna-se necessário o uso de modelos alternativos para a formação planetária, que sejam capazes de reproduzir os resultados de uma simulação N-corpos de forma confiável. Construir um modelo que considera a acreção de sólidos e gás é uma tarefa árdua e ao mesmo tempo desafiadora. Assim, o presente projeto propõe a implementação de um cenário fisicamente plausível para a formação planetária dentro do código magneto hidrodinâmico FARGO3D. Para modelar a acreção de planetesimais, usamos como base os trabalhos de Guilera et al. (2010) e Fortier et al. (2013), que utilizam um modelo estatstico para determinar a taxa de acreção de planetesimais (Inaba et al., 2001). Esse modelo será implementado pela primeira vez no FARGO3D. Atualmente, sabe-se que a acreção de peebles (material sólido entre cm e mm) tem um impacto importante na formação planetária (Lambrechts e Johansen, 2014; Guilera, 2016; Johansen e Lambrechts, 2017). No entanto, núcleos de poucas massas terrestres possuem um envelope planetário que poderia destruir esses pebbles antes dele alcançar o núcleo (Venturini et al., 2015). Nesta tese, iremos nos preocupar apenas com a acreção de planetesimais, deixando o estudo do pebbles para trabalhos futuros. Para a acreção de gás, iremos modificar o modelo de Kley (1999) incorporado no FARGO antecessor. Essas modificações visam incorporar o raio de Bondi (Bondi, 1952) para determinar a zona de acreção, o efeito da altura do disco e a mudança na taxa de acreção de gás de acordo com a massa do planeta. As modificações implementadas no modelo de acreção de gás foram realizadas com base nos trabalhos de Dürmann e Kley (2015), Russell (2011) e Fortier et al. (2013). A adaptação no código de acreção de gás para levar em conta uma faixa maior de massas planetárias foi realizada utilizando a escala de tempo de Kelvin-Helmoltz. Para isso, seguimos o trabalho de Ikoma et al. (2000) e Idae Lin (2004b). Para testar o modelo de formação planetária no FARGO3D, a simulação padrão para o disco de gás utilizada nesta tese adota um disco bidimensional fino com taxa de acreção constante. A razão de aspecto do disco será de h = 0.05 com um fator de curvatura de = 0.0. Esses valores são consistentes com a teoria de discos finos e são usados nas maioria das simulações que envolvem discos de acreção (Bell et al., 1997; Frank et al., 2002). O disco é assumido localmente isotérmico e a viscosidade do disco é dirigida pela prescrição de Shakura e Sunyaev (1973), com = 0.03. O modelo de disco é simplificado e caractersticas importantes podem influenciar no processo de formação e migração planetária, como as trocas de energia. No entanto, ele é um ótimo modelo inicial para um teste consistente do modelo de formação planetária implementado, já que possui um resultado analtico conhecido. Casos mais complexos serão explorados em trabalhos futuros. Com o modelo de formação planetária implementado, foi possível estudar simultânea- mente a formação e a migração do planeta dentro do simulador hidrodinâmico. Isto é, analisamos a escala de tempo envolvida no processo de migração em conjunto com a escala de tempo da formação planetária para vários parâmetros fsicos envolvidos no modelo. A análise revelou, para nosso modelo de disco, que a escala de crescimento do planeta conseguiu se manter mais baixa que a escala de migração, mesmo quando o planeta atravessou a linha de gelo, local onde há menor quantidade de material disponvel para a acreção de sólidos. Assim, para planetesimais pequenos (raio 0.1 km), foi possvel obter planetas com massas próximas de 5 massas de Júpiter em regiões entre 0.5 e 1 ua, num tempo menor que o tempo de vida do disco. Vale ressaltar que esta tese conta com uma descrição detalhada de como implementar o modelo dentro do FARGO3D, incluindo um apêndice com o programa comentado linha a linha. O intuito é que o leitor possa usar esse modelo de formação e migração planetária para obter novos resultados e vnculos sobre a formação de sistemas exoplanetários ou do nosso Sistema Solar, assim como usar em qualquer outra aplicação que julgar necessária. / According to the sequential model of accretion, the giant planets are formed from a solid nucleus by capturing planetesimals. When this nucleus reaches a certain mass, it captures the residual gas of the protoplanetary disc that will constitute its envelope, forming a giant planet (Mizuno, 1980; Pollack et al., 1996). The critical part of this scenario is to adjust the planet formation and migration timescales with the lifetime of the disk (Mordasini et al., 2010). Numerical results show that the time required for the formation of a giant planet is very long compared to the lifetime of the disc, and that planetary migration can be very rapid, causing the planets to fall into the star before their full formation. In general, works on planetary formation use analytical models to deal with the migration of the planets (Fortier et al., 2013). However, these analytical models are limited given that they do not include several effects associated with the thermodynamics of the gas disc (Paardekooper et al., 2010). Indeed, in order to deal with planetary migration of type I, these analytical models use physically simple gas discs and rely on the linearization of the hydrodynamic equations (Meyer-Vernet e Sicardy, 1987; Tanaka et al., 2002). For the type II migration, the situation is even more complicated. This is due to the fact that the large mass of the planet creates a gap around the orbit of the planet, causing nonlinearities (Bryden e Lin, 1999). Thus, the numerical results obtained using hydrodynamic simulators, such as FARGO3D (Masset, 2000; Bentez-Llambay e Masset, 2016), ZEUS (Stone e Norman, 1992), PLUTO (Mignone et al., 2012), among others, are essential for a more robust analysis of the processes of planetary migration considering a wider range of physical conditions for the gas disc. However, in general, hydrodynamic simulators do not have a model for the planetaryformation. In some of them, models for gas accretion are built based of the runaway regime of accretion (Kley, 1999). Furthermore, the accretion of solids and the accretion of gas for low mass planets are not considered in most of the cases. This is mainly due to the fact that the models of planetary formation use N-body simulations that are computationally very expensive. Thus, it is necessary to use alternative models for the planetary formation, that are capable of reproducing the same results of an N-body simulation. Building a complete model that takes into account all these processes is a hard and challenging task. So, this project aims the implementation of a physically plausible scenario for a planetary formation inside the magneto-hydrodynamic code FARGO3D. For the accretion model we use the works by Guilera et al. (2010) and Fortier et al. (2013), which employ an statistical model to determine the accretion rate of planetesimals (Inaba et al., 2001). This model will be implemented for the first time in the FARGO3D code. It is now known that the accretion of peebles (material with size ranging from mm and cm) has a important impact on the planetary formation (Lambrechts e Johansen, 2014; Guilera, 2016; Johansen e Lambrechts, 2017), although cores with a few masses of the Earth have a planetary envelope that could destroy those pebbles, before they reach the nucleus (Venturini et al., 2015). In this thesis, we will only deal with the accretion of planetesimals, leaving the study of pebbles for future work. For the gas accretion, we use a modified model based on Kley (1999). The modifications aim to incorporate the Bondi radius (Bondi, 1952) to determine the accretion zone, the effect of the height of the disc and the frequency of accretion. The implemented modifications are based on the works by Dürmann e Kley (2015), Russell (2011) and Fortier et al. (2013). The adaptation in the gas accretion code to take into account a wider range of planetary masses was achieved using the Kelvin-Helmoltz timescale, according to the works by Ikoma et al. (2000) and Ida e Lin (2004b). To test the planetary formation model in FARGO3D, the standard simulation for the gas disc uses a bi-dimensional thin disc. The discs aspect ratio is h = 0.05 with a curvature factor of = 0.0. These values are consistent with the theory of thin dics and are used in most of the simulations for accretion discs (Bell et al., 1997; Frank et al., 2002). The disc is assumed to be locally isothermal and the viscosity of the disc is driven by the prescription from Shakura e Sunyaev (1973), with = 0.03. The disc model is simplified and important features, such as energy exchanges, may influence the process of planetary formation andmigration. However, it is a good initial model for a consistent test of the implemented model of planetary formation, which has an known analysical result. More complex cases will be explored in future work. With the newly implemented model for planetary formation, it was possible to simul- taneously study the planet formation and the planet migration using the hydrodynamic simulator. That is, we analyzed both the timescale for planetary formation and the timescale for the migration of the planet, and compared them for the parameters of the model. The analysis revealed that, for our disc model, the timescale of the growth rate of the planet remained lower than the migration timescale, even when the planet crossed the ice line, where there is less material available for solid accretion. Thus, for small planetesimals (1km radius) it was possible to obtain planets with masses of approximately 5 Jupiter masses in regions between 0.5 and 1 au, in nearly the same time as the lifetime of the disc. It is worth noting that this thesis presents a detailed description of how to implement the model for planetary formation in the FARGO3D, including an appendix with the commented code. The goal is to allow the reader to use this planet formation model to obtain new results both about the formation of exoplanetary systems and our Solar System, as well as use it in any relevant application.
243

Möjligheten att servera klimatsmart mat i skolmåltidsverksamheter : Ett case från Karlstad kommun / Opportunities to serve climate-smart food in school canteenes : A case from Karlstad community

Broström, Linda January 2019 (has links)
Karlstad kommun har de senaste åren arbetat med projektet ”Klimatsmart mat” där kommunen fokuserat på hållbarhetsfrågor inom måltidsverksamheter i skolor. Konceptet One planet plate har testats för första gången i skolor och Karlstad kommun var först ut i Sverige att prova.  Det här är en kvalitativ studie som har genomförts via personliga intervjuer med fyra stycken kostansvariga på de skolor som var utvalda att delta i One planet platesamt kommunens koststrateg. Syftet med studien har varit att undersöka hur de utvalda skolorna upplever att konceptet har fungerat på deras arbetsplats samt vilka möjligheter och hinder de upplever att det klimatsmarta arbetet ger upphov till. Studien har visat att One planet platehar upplevts som ett konkret och enkelt verktyg för de kostansvariga att använda sig av. Det har dock tagit mycket tid och planering att skapa recept som håller sig inom gränsvärdet för koldioxidutsläpp. För att förbättra konceptet föreslås att måltiderna bör kombineras med pedagogisk undervisning angående matens klimatpåverkan för att skapa en bättre förståelse hos eleverna.  I det klimatsmarta arbetet har flera hinder och möjligheter beskrivits och de viktigaste handlar om ekonomiska förutsättningar och politikers makt att påverka. Även att erbjuda klimatsmart mat från tidig ålder har lyfts som betydande för att kunna förändra attityder och kunskap som skapar långsiktiga hållbara vanor. / Karlstad community has been working with the project ”Climate-smart food” where the community in the past years has been focusing on sustainability questions within school canteens. The concept ”One planet plate” has been tested for the first time in schools and Karlstad community was the first in Sweden to try it. This is a qualitative study, carried out by interviewing those four people responsible for catering at the selected schools within one planet plateand the food strategist of the community. The purpose of this study have been to examine how the chosen schools experience that the concept have worked on their working place and which opportunities and obstacles they find the climate smart work causes. The study have found that one planet platehas been perceived as a concrete and easy tool for those responsible of the cantines to use. However, it has been time consuming to create recipes whitin the limits of carbon emissions. To improve the concept they suggest to combine the meals with educational teaching concerning the climate impact of food, to create a better understanding for the students. In the climate-smart work various obstacles and opportunities were described and the most important concerns financial prerequisites and the power politicians have to affect. Also, to offer climate-smart food from an early age have been lifted as important to be able to change attitudes and knowledge that creates long-term sustainable habits.
244

Organisationsmarknadsföring : En fallstudie av IBMs internkommunikation

Brindt, Thomas, Eriksson, Aurora January 2010 (has links)
<p>Ett organisationsvarumärke har flera påtagliga fördelar: Det förmedlar ett företags kärnvärden, det ger företaget en möjlighet att särskilja sig från sina konkurrenter och det utgör en överlägsen kommunikationsfördel gentemot företagets intressenter. Med detta sagt är ett starkt organisationsvarumärke eftersträvansvärt. För att lyckas med organisationsmarknadsföring krävs dock att hela företaget organiserar sig och deltar och här är den interna kommunikationen i organisationen nyckeln för att lyckas på lång sikt. Följaktligen är syftet och utgångspunkten i denna uppsats att; undersöka IBMs strategi "En smartare planet" med fokus på den interna kommunikationen i företaget utifrån de anställdas egna upplevelser – med motivet att möjliggöra en jämförelse med den normativa teori som berör organisationsvarumärken. För att uppfylla vårt syfte utför vi en fallstudie eftersom vi undersöker en specifik organisation och då vill avgränsa oss i tid och rum. Undersökningen visar att IBM begagnar sig av nydanande kommunikationsmetoder som skapar möjligheter till kommunikation mellan ledning och anställda som tidigare ansetts vara omöjliga. Studien visar att det senaste decenniets tekniska utveckling har medfört nya interna kommunikationsmöjligheter och gjort ämnet till ett högintressant forskningsområde.</p>
245

Morphology and dynamics of the Io UV footprint/Morphologie et dynamique de l'empreinte aurorale UV d'Io

Bonfond, Bertrand 26 October 2009 (has links)
The Io UV footprint (IFP) is one of the most spectacular signatures of the Io-Jupiter interaction. It consists of several auroral spots and an extended tail which are located close to the feet of the magnetic field lines passing through Io in each hemisphere. The purpose of the present study is to demonstrate that a careful analysis of the Io UV footprint based on observations acquired with the STIS and ACS high resolution and high sensitivity FUV cameras on board the Hubble Space Telescope can provide us with essential information on the ongoing physical processes. The thesis is organized around basic questions: What is the Io footprint?, Where is the Io footprint?, How high is the Io footprint?, How big is the Io footprint? and finally: How bright is the Io footprint? The answers to these questions have profound implications for the understanding of the phenomenon. Among the most important results of this work is the unexpected finding of a faint auroral spot appearing upstream of the main Io spot in one hemisphere while only downstream spots are seen in the opposite hemisphere. The detailed study of the evolution of the inter-spot distances puts previous models describing the footprint morphology under question. We propose a new interpretation which involves that some spots are caused by electrons accelerated away from the planet along the field lines in one hemisphere, crossing the equatorial plane in the form of electron beams and precipitating in the opposite hemisphere, creating the so-called Trans-hemispheric Electron Beam (TEB) spots. The information provided by the position of the satellite footprints is not restricted to the interaction between the moon and the Jovian magnetosphere. The analysis of the footpaths of Io, Europa and Ganymede helped us to further constrain the magnetic field models, notably through the identification of a large magnetic anomaly in the northern hemisphere. Additionally, the study of the speed of the Io footprint along its reference contour suggests that a second anomaly regions may also exist in the North. In this work, we present a new and direct method to measure the altitude of the different footprint features. The main spot and the tail emissions have a peak altitude of 900 km while the peak altitude of the Trans-hemispheric Electron Beam spot is 700 km. These results suggest that the main spot and tail emissions are caused by the precipitation of electrons with a mean energy around 1 keV, far lower than the 55 keV value previously derived from spectral measurements. The vertical extent of these emissions is surprisingly broad (scale height ~400 km) and is best fitted with an incoming kappa electron energy distribution (spectral index ~2.3). This suggests that the electron acceleration is supplied by processes related to inertial Alfvén waves rather than by quasi-static potentials as proposed by some theoretical models. The size of the main footprint spot is carefully estimated on a much larger image sample than before: its length along the footpath is ~900 km while its width perpendicular to the footpath is <200 km. Larger lengths are sometimes observed but in that case, they are attributed to the mix of individual spots. The spot length is larger than the projected diameter of Io around the magnetic field lines but is consistent with recent simulations. As far as the Io footprint brightness is concerned, variations on two timescales have been studied. On timescales of minutes, systematic brightness fluctuation on the order of 30% (and going up to 50%) are observed. Additionally, cases of simultaneous variations of the main and the TEB spots are reported, which suggests that the process that triggers these fast variations is located close to the planet. Variations of the main spot brightness with the System III longitude of Io are also analyzed. Our new measurement method fully considering the multi-spot structure of the IFP and the real geometry of the observations provides more accurate estimates for the precipitating energy flux (between 100 and 500 mW/m for the main spot). The main spot brightness peaks at 110° and 290° longitude, which could be attributed either to an enhanced interaction strength when Io is near the dense torus center or to spots merging which is also observed to occur in these sector. Nevertheless, strong North-South asymmetries are also observed, which suggests that the surface magnetic field strength also influences the spots brightness. ---------------------------------------------------------------------- L'empreinte aurorale d'Io est l'une des signatures les plus impressionnantes de l'interaction Io-Jupiter. Présente dans chaque hémisphère, elle se situe à proximité des pieds des lignes de champ magnétique qui interceptent Io et se compose de plusieurs taches suivies d'une longue trainée. Cette étude vise à démontrer qu'une analyse minutieuse de l'empreinte UV d'Io basée sur les observations des instruments STIS et ACS du Télescope Spatial Hubble peut apporter des informations cruciales sur les processus physiques qui sont en jeu. Cette thèse est organisée autour de questions relativement basiques: Qu'est-ce que l'empreinte d'Io?, Où se trouve-t-elle?, A quelle altitude se trouve-t-elle?, Quelle est sa taille? et enfin Quelle est sa brillance?. Les réponses à ces questions ont de profondes implications pour la compréhension du phénomène. Parmi les résultats principaux de ce travail, il y a la découverte inattendue d'une faible tache aurorale apparaissant en amont de la tache principale dans un hémisphère alors que les seules taches observées dans l'hémisphère opposé sont situées en aval. L'étude détaillée de la distance inter-taches remet en question les précédents modèles décrivant la morphologie de l'empreinte. Nous proposons ici une nouvelle interprétation de certaines de ces taches: elles seraient causées par des électrons initialement accélérés le long des lignes de champ dans la direction opposée à Jupiter, qui ensuite traverseraient le plan équatorial sous la forme de faisceaux d'électrons et qui précipiteraient finalement dans l'hémisphère opposé en générant la tache du Faisceau d'Electrons Trans-hemisphérique (FET). Les informations fournies par la position des empreintes de satellites ne se limitent pas à l'interaction entre Io et la magnétosphère de Jupiter. L'analyse des contours parcourus par les empreintes d'Io, d'Europe et de Ganymède permet de mieux contraindre les modèles de champ magnétique joviens, entre autre à travers l'identification d'une importante anomalie magnétique dans l'hémisphère nord. De plus, l'étude de la vitesse de l'empreinte d'Io le long du contour de référence suggère qu'elle pourrait être accompagnée d'une deuxième anomalie dans cet hémisphère. Dans cette étude, nous présentons une méthode directe pour mesurer l'altitude des différentes sous-structures qui forment l'empreinte. Le pic d'émissions de la tache principale et de la trainée est situé à 900 km d'altitude alors que celui de la tache FET est à 700 km. Ces résultats suggèrent que la tache principale et la trainée sont la conséquence de la précipitation d'électrons ayant une énergie moyenne d'approximativement 1 keV, une valeur largement inférieure aux 55 keV déduits à partir de précédentes mesures spectrales. L'extension verticale de ces émissions est étonnamment large (hauteur d'échelle: ~400 km) et la distribution d'énergie des électrons incidents qui reproduit au mieux les observations est une distribution kappa d'indice spectral ~2.3. Cela suggère que l'accélération des électrons est liée à des ondes d'Alfvén inertielles plutôt qu'aux potentiels quasi-statiques proposés par certains modèles théoriques. La taille de la tache principale a été mesurée sur un ensemble d'images beaucoup plus étendu qu'auparavant: sa longueur le long du contour est de ~900 km alors que sa largeur telle que mesurée perpendiculairement à celui-ci est de <200 km. Des longueurs plus importants sont parfois observées mais elles résultent de la superposition partielle de plusieurs taches individuelles. La longueur des taches est plus grande que la projection du diamètre d'Io le long des lignes de champ, ce qui était prévu par des simulations récentes. En ce qui concerne la brillance des taches, deux échelles de temps ont été étudiées en particulier. A l'échelle de la minute, nous avons mis en évidence des fluctuations de l'ordre de 30% de la brillance moyenne et pouvant atteindre jusqu'à 50 % de celle-ci. Dans certains cas, on observe des variations corrélées de la tache principale et de la tache FET, ce qui suggère que le processus qui induit ces variations rapides se situe près de la surface de Jupiter. Les variations de la brillance de la tache principale en fonction de la longitude Système III d'Io ont également été analysées. Notre nouvelle méthode de mesure prend pleinement en compte la géométrie de l'observation ainsi que le fait que l'empreinte est composée de différentes taches, ce qui permet une estimation plus précise du flux d'énergie incident (entre 100 et 500 mW/m pour la tache principale). La brillance de la tache principale possède deux maxima, un à 110° et un autre à 290° de longitude. Ces augmentations de brillance peuvent avoir deux origines: soit elles sont dues à l'augmentation de l'intensité de l'interaction entre Io et le plasma quand Io est proche du centre du tore, soit elles sont liées à la superposition des taches principales et FET qui se produit également dans ces secteurs. Néanmoins, de fortes asymétries Nord-Sud sont aussi observées, ce qui semble indiquer que l'intensité du champ magnétique de surface joue aussi un rôle en ce qui concerne la brillance des spots.
246

Organisationsmarknadsföring : En fallstudie av IBMs internkommunikation

Brindt, Thomas, Eriksson, Aurora January 2010 (has links)
Ett organisationsvarumärke har flera påtagliga fördelar: Det förmedlar ett företags kärnvärden, det ger företaget en möjlighet att särskilja sig från sina konkurrenter och det utgör en överlägsen kommunikationsfördel gentemot företagets intressenter. Med detta sagt är ett starkt organisationsvarumärke eftersträvansvärt. För att lyckas med organisationsmarknadsföring krävs dock att hela företaget organiserar sig och deltar och här är den interna kommunikationen i organisationen nyckeln för att lyckas på lång sikt. Följaktligen är syftet och utgångspunkten i denna uppsats att; undersöka IBMs strategi "En smartare planet" med fokus på den interna kommunikationen i företaget utifrån de anställdas egna upplevelser – med motivet att möjliggöra en jämförelse med den normativa teori som berör organisationsvarumärken. För att uppfylla vårt syfte utför vi en fallstudie eftersom vi undersöker en specifik organisation och då vill avgränsa oss i tid och rum. Undersökningen visar att IBM begagnar sig av nydanande kommunikationsmetoder som skapar möjligheter till kommunikation mellan ledning och anställda som tidigare ansetts vara omöjliga. Studien visar att det senaste decenniets tekniska utveckling har medfört nya interna kommunikationsmöjligheter och gjort ämnet till ett högintressant forskningsområde.
247

Den obekväma planeten : En analys av retoriken i dokumentärfilmerna An Inconvenient Truth och The Planet / The inconvenient planet : An analysis of the rhetoric in the documentaries An inconvienent Truth and The Planet

Klittmark, Jonathan, Venström, Pontus January 2008 (has links)
An Inconvenient Truth (2006) och The planet (2006) är två stycken dokumentärfilmer som behandlar klimathotet och dess globala följder. Uppsatsen diskuterar den retoriska meningen och de retoriska skiljaktigheter, likheter mellan dokumentärfilmerna. Den diskuterar även syftet av de filmsekvenser som används till varje tal/intervju. Uppsatsen innehåller analyser av varje film samt en analyssummering mellan båda filmerna. An Inconvenient Truth (2006) är en dokumentärfilm med fokus på Al Gores och hans kampanj där han försöker informera folk gällande klimathotet. The Planet (2006) är en dokumentärfilm med olika typer av forskare och experter som med hjälp av statistik från forskning belyser vad som händer och kommer att hända med planeten. / An Inconvenient Truth (2006) and The Planet (2006) are both documentaries with focus on the climate change and its global causes. This report discusses the rhetorical meaning and rhetorical differences, likenesses between the documentaries. It also discusses the purpose in choosing types of visual scenes to each speech/interweave. The report contain analyzes of each movie and a analyze summit between both movies. An Inconvenient Truth (2006) is a documentary with the focus on Al Gore with his campaign to inform people about the climate change. The Planet (2006) is a documentary including different kind of scientists and experts who use statistics from their research to show what is happening and what will happen to the planet.
248

Det riktiga Kenya och orientaliska Tunisien : En diskursanalys av Lonely Planets guideböcker om Tunisien och Kenya

Ekelund Nord, Lina January 2012 (has links)
Presentations of Oriental people as subordinated the West and their ideals was one way for Europeans to expand and keep control over their colonies in Africa during the nineteenth- and twentieth centuries. France and Great Britain controlled their colonies in different ways which has led to diverse legacies. Today, tourism is a source of revenue for former colonies, such as Tunisia and Kenya, and tourism also helps to spread knowledge and images of distant countries. A guidebook is one way that knowledge of other countries and people are spread to travelers. During history, images of distant people were based on a colonial discourse in which the west was seen as superior; but is that still the case? The purpose of this paper was to analyze how Tunisia and Kenya are presented in the Lonely Planet guide to Tunisia and the Lonely Planet guide to Kenya to investigate if they are constructed through a colonial discourse, and to see if there are any dissimilarities on how they are presented. With a postcolonial theory and critical discourse analysis and with a colonial discourse as framework, the guidebooks were examined to see how people and culture were presented. The research showed that Lonely Planet guidebooks use a colonial discourse in the presentation of Tunisia and Kenya where distinctions are made between the inhabitants and the western world. The Orient was subordinated the superior Occident which reinforces the notion of others as being different and less than the west. Diversities between how Tunisia and Kenya were drawn in the guidebooks were found. The colonial heritage was more present in Tunisia than in Kenya, while in Kenya the people were presented as more brutal than in Tunisia. Reasons for that could be many, but the critical issue is why the western world still constructs other people as subordinate and different.
249

In search of water vapor on Jupiter: laboratory measurements of the microwave properties of water vapor and simulations of Jupiter's microwave emission in support of the Juno mission

Karpowicz, Bryan Mills 15 January 2010 (has links)
This research has involved the conduct of a series of laboratory measurements of the centimeter-wavelength opacity of water vapor along with the development of a hybrid radiative transfer ray-tracing simulator for the atmosphere of Jupiter which employs a model for water vapor opacity derived from the measurements. For this study an existing Georgia Tech high-sensitivity microwave measurement system (Hanley and Steffes , 2007) has been adapted for pressures ranging from 12-100 bars, and a corresponding temperature range of 293-525°K. Water vapor is measured in a mixture of hydrogen and helium. Using these measurements which covered a wavelength range of 6--20 cm, a new model is developed for water vapor absorption under Jovian conditions. In conjunction with our laboratory measurements, and the development of a new model for water vapor absorption, we conduct sensitivity studies of water vapor microwave emission in the Jovian atmosphere using a hybrid radiative transfer ray-tracing simulator. The approach has been used previously for Saturn (Hoffman, 2001), and Venus (Jenkins et al., 2001). This model has been adapted to include the antenna patterns typical of the NASA Juno Mission microwave radiometer (NASA/Juno -MWR) along with Jupiter's geometric parameters (oblateness), and atmospheric conditions. Using this adapted model we perform rigorous sensitivity tests for water vapor in the Jovian atmosphere. This work will directly improve our understanding of microwave absorption by atmospheric water vapor at Jupiter, and improve retrievals from the Juno microwave radiometer. Indirectly, this work will help to refine models for the formation of Jupiter and the entire solar system through an improved understanding of the planet-wide abundance of water vapor which will result from the successful opreation of the Juno Microwave Radiometer (Juno-MWR).
250

Den obekväma planeten : En analys av retoriken i dokumentärfilmerna An Inconvenient Truth och The Planet / The inconvenient planet : An analysis of the rhetoric in the documentaries An inconvienent Truth and The Planet

Klittmark, Jonathan, Venström, Pontus January 2008 (has links)
<p>An Inconvenient Truth (2006) och The planet (2006) är två stycken dokumentärfilmer som behandlar klimathotet och dess globala följder. Uppsatsen diskuterar den retoriska meningen och de retoriska skiljaktigheter, likheter mellan dokumentärfilmerna. Den diskuterar även syftet av de filmsekvenser som används till varje tal/intervju. Uppsatsen innehåller analyser av varje film samt en analyssummering mellan båda filmerna. An Inconvenient Truth (2006) är en dokumentärfilm med fokus på Al Gores och hans kampanj där han försöker informera folk gällande klimathotet. The Planet (2006) är en dokumentärfilm med olika typer av forskare och experter som med hjälp av statistik från forskning belyser vad som händer och kommer att hända med planeten.</p> / <p>An Inconvenient Truth (2006) and The Planet (2006) are both documentaries with focus on the climate change and its global causes. This report discusses the rhetorical meaning and rhetorical differences, likenesses between the documentaries. It also discusses the purpose in choosing types of visual scenes to each speech/interweave. The report contain analyzes of each movie and a analyze summit between both movies. An Inconvenient Truth (2006) is a documentary with the focus on Al Gore with his campaign to inform people about the climate change. The Planet (2006) is a documentary including different kind of scientists and experts who use statistics from their research to show what is happening and what will happen to the planet.</p>

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