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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.
121

Geomagnetically induced current characteristics in southern Africa

Ngwira, Chigomezyo Mudala January 2009 (has links)
Geomagnetically induced currents (GICs), resulting from adverse space weather, have been demonstrated to cause damage to power transformers at mid-latitudes. There is growing concern over possible GIC effects in the Southern African network due to its long power lines. Previous efforts to model the electric field associated with GICs in the Southern Africa region used a uniform ground conductivity model. In an effort to improve the modelling of GICs, GIC data together with Hermanus Magnetic Observatory geomagnetic field data were used to obtain a multilayered ground conductivity model. This process requires a definition of the network coefficients, which are then used in subsequent calculations. This study shows that GIC computed with the new network coefficients and the multilayered ground conductivity model improves the accuracy of GIC modelling. Then GIC statistics are derived based on the recordings of the geomagnetic field at Hermanus, the new network coefficients and ground conductivity model. The geoelectric field is modelled using the plane wave method. The properties of the geomagnetic field, their time derivatives and local geomagnetic indices were investigated to determine their characteristics in relation to the GIC. The pattern of the time derivatives of the horizontal geomagnetic field closely follow the rate of change of the north-south geomagnetic component rather than the east-west component. The correlation between the GIC and the local geomagnetic field indices was also investigated. The results show that there is a higher correlation between the GIC and the east-west components of the geomagnetic local indices than between the GIC and the north-south components. This corresponds very well with the orientation of the power lines feeding the power transformers at the South African Grassridge electrical substation GIC site. Thus, the geoelectric field driving the GIC at Grassridge is north-south oriented. Further, it is shown that the geomagnetic observation sites have a strong directional preference with respect to the Grassridge GIC site.
122

Světelné znečištění v okolí hvězdárny Ondřejov / Light pollution in the vicinity of the Ondřejov Observatory

Kocourek, David January 2017 (has links)
Light pollution is currently one of the environmental problems of human society. With the technological development and the increase of the human population on the planet, the landscape is constantly increasing the emission of disturbing light into the surrounding area during the night. The largest producer of light pollution is the urban and suburban regions where light spreads to several decades away, increasing the brightness of the sky, as well as rural or nature-close landscapes. Exposure to disturbing light has a demonstrably unfavorable effect on human, animal and plant health as well as on the balance of whole ecosystems. In this work I focus on finding and assessing the state of sky brightness in the interest zone of the observatory of Astronomical Institute AV at Ondřejov. Based on my own data measured in the field during nine night excursions, I created an interpolated map of ArcMap 10.2 and, according to directional measurements, interpreted the main polluters in this area. The results clearly show a clear trend to reduce the sky's brightness from the northwest to the east. The measurements also show that the local sources of obstrusive light near Ondřejov have a slight influence on the overall zenith brightness of the sky compared to the presence of Prague, several miles away....
123

Stellar Works: Searching for the Lives of Women in Science

Woodman, Jennifer Elizabeth 07 June 2016 (has links)
While women have had a profound impact in the world of science, they struggle to gain an equal foothold in many science, technology, engineering, and mathematics (STEM) fields today. This has led to considerable public and private sector efforts to recruit women into these arenas. In order to understand how schools and nonprofits engage today's young women in STEM studies, this account includes time spent both in high school science classrooms and with ChickTech -- a Portland-based organization that works to provide a pathway into tech careers for high school-aged girls. A historical perspective reveals that modern women aren't treading into completely uncharted territory, in spite of the current disparity of representation in today's STEM arenas. This perspective is offered via an examination of the lives of a group of extraordinary women who worked in astronomy at Harvard College Observatory from the late 1800s into the 1960s. While several noteworthy women are discussed, the focus here is on Cecilia Payne, the first person to earn a Ph.D. in astronomy at Harvard, and one of the 20th century's greatest astronomers. A great many people have never heard of her . . . yet.
124

Cosmic-ray astronomy at the highest energies with ten years of data of the Pierre Auger observatory / Astronomie à rayons cosmiques d'ultra-haute énergie avec dix ans de données de l'observatoire Pierre Auger

Caccianiga, Lorenzo 14 September 2015 (has links)
L'identification des sources de rayons cosmiques d'ultra-haute énergie (au-delà de 10^18 eV) constituerait une avancée majeure aussi bien dans le domaine de l'astrophysique que dans celui de la physique des particules. La difficulté principale dans la recherche de telles sources réside dans la perte de l'information directionnelle des rayons cosmiques les moins énergétiques. En effet, leur direction est sujette à des déviations d'amplitude inversement proportionnelle à leur énergie à cause des champs magnétiques qu'il traversent lors de leur propagation jusqu'à la Terre. D'autre part, pour des énergies supérieures à 4x10^(19)eV, l'interaction des rayons cosmiques avec le fond diffus cosmologique limite l'horizon de leurs sources à l'Univers proche (200 Mpc ou moins). Cette thèse a été effectuée au sein de l’observatoire Pierre Auger, le plus grand détecteur de rayons cosmiques de haute énergie. Elle est dédiée à l'étude, la sélection, la reconstruction, ainsi qu'à l'analyse des évènements de plus haute énergie. D'autre part, les particules de plus bas numéro atomique sont plus susceptibles de garder leur direction mais la composition des rayons cosmiques est inconnue à de telles énergies. Une méthode de sélection des événements les plus similaires aux protons a été élaborée et développée dans cette thèse pour étudier la possibilité de leur utilisation pour une "astronomie protons" / Identifying the sources of the ultra-high energy cosmic rays (UHECRs, above 10^{18} eV), the most energetic particles known in the universe, would be an important leap forward for both the astrophysics and particle physics knowledge. However, developing a cosmic-ray astronomy is arduous because magnetic fields, that permeate our Galaxy and the extra-Galactic space, deflect cosmic rays that may lose the directional information on their sources. This problem can be reduced by studying the highest energy end of the cosmic ray spectrum. Indeed, magnetic field deflections are inversely proportional to the cosmic ray energy. Moreover, above 4x10^{19} eV, cosmic rays interact with cosmic photon backgrounds, losing energy. This means that the sources of the highest energy cosmic rays observed on Earth can be located only in the nearby universe (200 Mpc or less). The largest detector ever built for detecting cosmic rays at such high energies is the Pierre Auger Observatory, in Argentina. It combines a 3000 km^2 surface array of water Cherenkov detectors with fluorescence telescopes to measure extensive air showers initiated by the UHECRs. This thesis was developed inside the Auger Collaboration and was devoted to study the highest energy events observed by Auger, starting from the selection and reconstruction up to the analysis of their distribution in the sky. Moreover, since the composition at these energies is unknown, we developed a method to select proton-like events, since high Z cosmic rays are too much deflected by magnetic fields to be used for cosmic-ray astronomy.
125

L'ingénierie territoriale à l’épreuve des observatoires territoriaux : analyse des compétences des professionnels du développement dans le massif pyrénéen / Territorial engineering and territorial observatory : skills of territorial development professionals in the Pyrenees Mountain

Lenormand, Pauline 25 November 2011 (has links)
Cette thèse s’intéresse aux transformations et modalités de mise en œuvre de l’ingénierie territoriale. Elle se propose de l’analyser à travers l’émergence d’un nouvel instrument, l’observatoire territorial. Elle pose comme hypothèse que les compétences des professionnels du développement territorial sont déterminantes dans l’efficacité de cette ingénierie et qu’en retour, la structuration de celle-ci influe fortement sur l’évolution de ces compétences. Nous nous intéressons à la conception et aux usages d’observatoires sur les Pyrénées en mobilisant l’entretien auprès des acteurs de ces projets et à travers une position d’observation participante au sein d’une structure d’expertise territoriale.Les projets d’observatoire révèlent un enjeu de construction de compétences collectives dans l’ingénierie territoriale, indispensables pour ancrer l’expertise dans le territoire. Cet enjeu se déploie à différents niveaux : entre agents d’une même structure et entre agents de différentes structures. Ces niveaux font apparaître des médiateurs favorisant l’émergence et la consolidation des compétences collectives. Ces processus entraînent des transformations des compétences individuelles des professionnels ainsi qu’un métissage de celles-ci, aboutissant à l’émergence de profils professionnels hybrides. Par rapport aux compétences mobilisées dans des projets de développement territorial, celles nécessaires au projet d’observatoire territorial sont marquées par un besoin plus fort de stratégie, tout en faisant appel à des compétences techniques spécialisées. L’approche géographique de la compétence comme ressource de la construction territoriale est une avancée majeure de cette thèse. / This thesis is concerned with transformations and the different means for implementing territorial engineering. Its aim is to analyse territorial engineering through the emergence of a new instrument, the territorial observatory. It advances the hypothesis that the skills of territorial development professionals play a key role in the effectiveness of this engineering, whereas the way it is structured highly influences the evolution of these skills. We focus on the design and uses of observatories in the Pyrenees Mountains through interviews with the actors who participate in these projects, as well as from the viewpoint of a participating observer within a territorial expertise structure. Observatory projects illustrate the challenge involved in the construction of collective skills for territorial engineering, essential for integrating expertise into the territorial framework. This challenge exists at different levels : between representatives of the same structure and between representatives of different structures. These levels give rise to mediators who encourage the emergence and the consolidation of collective skills. These processes lead to transformations in the individual skills of professionals as well as a crossover between them, thus resulting in the emergence of hybrid professional profiles. In relationship to the overall skills mobilised in territorial development projects, those necessary for territorial observatory projects can be distinguished by a greater need for strategy, while requiring specialised technical skills. The geographic approach to skills as a resource for territorial construction is a major contribution of this thesis.
126

Habilidades de Leitura para o 5 ano a partir da matriz de referência da Prova Brasil : da teoria à prática

Jocimara Aparecida de Lima 05 April 2014 (has links)
A presente pesquisa enfoca as características das questões de leitura da Prova Brasil para o 5 ano do Ensino Fundamental e o desenvolvimento das habilidades de leitura exigidas por essa Prova. Insere-se no projeto observatório da Educação/UNITAU `Competências e habilidades de leitura; da reflexão teórica ao desenvolvimento e aplicação de propostas didático-pedagógicas, n23038010000201076, financiado por CAPES/INEP. Foi motivada pelo interesse dos professores em conhecer melhor a Prova Brasil para desenvolver nos alunos as habilidades leitoras e pelo fato de os alunos demonstrarem muitas dificuldades de compreensão textual. A pesquisa objetiva, de modo geral e no âmbito do Projeto Observatório/UNITAU, contribuir para oferecer subsídios para um trabalho focado no desenvolvimento de habilidades de leitura de alunos do 5 ano do Ensino fundamental. Especificamente os objetivos dessa pesquisa são: 1 Identificar os gêneros discursivos que aparecem nas questões da Prova Brasil para o 5 ano até 2011 e as habilidades de leitura cobradas nessas questões; 2 Desenvolver atividades de leitura em uma sala do 5 ano do ensino fundamental, focando nos três gêneros discursivos mais frequentemente utilizados na Prova Brasil, identificados no primeiro objetivo citado fábula, poema e tira , e refletir sobre os resultados obtidos. Fundamenta-se na concepção bakhtiniana de gêneros discursivos; na abordagem sociocognitiva de leitura; nos conceitos de competências e habilidades leitura; no conceito de sequência didática. Os procedimentos metodológicos da pesquisa dar-se-ão por meio de: análise qualitativo-interpretativista das questões da Prova Brasil para o 5 ano e de desenvolvimento de pesquisa-ação em uma sala de 5 ano de uma escola da rede municipal de Taubaté. Como resultados, observou-se que o levantamento sobre os gêneros discursivos das questões da Prova Brasil foi fundamental para encaminhar a pesquisa-ação e que as sequências didáticas de leitura e as coletâneas de textos foram muito eficientes para organizar um trabalho de leitura que explora as características dos gêneros discursivos alvo da leitura e mobiliza habilidades cobradas pela Prova Brasil. Os alunos mostraram-se interessados pelos textos e, pelos resultados das atividades, pudemos observar que se apropriaram das principais características dos gêneros, inclusive do poema, pouco conhecido por eles até a participação nesta pesquisa-ação. Conclui-se que atividades de leitura na perspectiva desenvolvida nesta pesquisa contribuem significativamente para o desenvolvimento de habilidades de leitura. / This research focuses on the characteristics of the reading and interpretation questions of `Prova Brasil for the 5th grade of Elementary School and on the development of reading skills required for this event. It is part of the project called UNITAU Education Observatory `reading competences and skills; from theoretical reflection to the development and implementation of educational and pedagogical proposals, number 23038010000201076, sponsored by CAPES / INEP. Its motivation was teachers interest to know `Prova Brasil better in order to develop students reading abilities and for the fact that many students show difficulties in reading comprehension. The research aims, in general and within the UNITAU Observatory Project, to help provide grants for a work focused on developing students reading skills in the 5th grade of Elementary School. Specifically, the objectives of this research are: 1) Identify the discursive genres that appear in questions of `Prova Brasil for the 5th grade until 2011 and the reading skills evaluated in these questions; 2) Develop reading activities in a 5th grade class, focusing on the three discursive genres, the ones most often found in `Prova Brasil, identified in the first mentioned purpose - fables, poems and strips - and reflect on the results. It is based on Bakhtins concept of discursive genres, on the sociocognitive approach to reading, on the concepts of reading competences and skills, on the concept of didactic sequence. The research methodological procedures are qualitative- interpretative analysis of the questions of `Prova Brasil for 5th grade and the development of action research in a 5th grade classroom of a school in the city of Taubaté. As a result, it was observed that the survey on the questions of discursive genres `Prova Brasil was very important to further the action research and that the reading didactic sequences and the collections of texts were very efficient to organize a reading work that explores the characteristics of target discursive genres and mobilizes skills evaluated in `Prova Brasil. Students were interested in the texts, and by the results of the activities, we conclude that they could learn the main features of the genres, including poems, little known by them until they participated in this action research. We concluded that reading activities in the perspective developed in this research can contribute significantly to the development of reading skills.
127

3D model hvězdárny ve Valašském Meziříčí / 3D model of observatory building in Valašské Meziříčí

Dubec, Marek January 2018 (has links)
The objective of the diploma thesis is creating digital 3D model of observatory building in Valašské Meziříčí. The building is measured by classical geodetic methods. The results of the thesis are the wired model, which is created in MicroStation V8i, and 3D model with textured surfaces, including visualization in form photos and video, which is created in AutoCAD 2018.
128

Kalibrace fluorescenčních detektorů kosmického záření s použitím astronomických metod / Kalibrace fluorescenčních detektorů kosmického záření s použitím astronomických metod

Kotíková, Irena January 2012 (has links)
This diploma thesis examines the possibilities of a new method of astronomical calibration at the Pierre Auger Observatory in Argentina. Its goal is to use stars as objects with known brightness to calibrate the fluorescence detectors and compare these results with the existing calibration. The analysis was done using computer programs which use the star catalog and experimental background data to compare the current calibration with our method. Results that are presented conclude that the calibration using stars is consistent with the existing calibration, however, the error of the new method is much higher. Nevertheless, there is a good potential for scale - it could be used for all past and future data. Potential improvements to this method and its error are suggested.
129

Temporal Variations in The Circumstellar Disks of Be Stars from Analysis of Optical and IR Line Profiles

Gerhartz, Cody J. January 2017 (has links)
No description available.
130

Opto-alimentation et transmission de données par fibre optique pour les observatoires de fond de mer / Power and data over fiber for seafloor observatories

Audo, Frédéric 03 December 2012 (has links)
Ce mémoire de thèse est consacré à l’étude d’une liaison tout-optique longue de 10 km dédiée à l’extension d’un observatoire câblé de fond de mer existant afin d’atteindre de nouvelles zones d’exploration. Les travaux de recherche qui y sont rapportés démontrent la faisabilité de cette liaison tout-optique entre un instrument déporté et une station terrestre avec une seule fibre optique longue de 10 km, qui transmet simultanément la puissance, nécessaire à l’alimentation de l’instrument (quelques centaines de milliwatts), et des données bidirectionnelles en temps réel.Le contexte de cette thèse est présenté au travers d’un état de l’art sur les observatoires câblés et sur la puissance sur fibre. Le choix de la fibre unique et la présence de fortes puissances optiques complexifient la mise en oeuvre de cette extension tout-optique, et sont à l’origine de l’apparition d'interactions entre l’énergie optique dédiée à l'alimentation (@1480 nm) et les données échangées (@1550 nm). Tout au long de ce document, les choix technologiques retenus sont argumentés et les effets optiques non linéaires tels que les diffusions Raman, Brillouin, Rayleigh, l’Émission Spontanée Amplifiée (ASE) sont décrits, modélisés et analysés expérimentalement. L’extension tout-optique proposée a été caractérisée à la fois en régimes statique et dynamique par des mesures du bilan de liaison, du rapport signal à bruit (SNR) et du taux d’erreur binaire (BER). Les résultats obtenus montrent la possibilité de fournir 160 mW électrique à l’instrument déporté en utilisant une source optique continue de 33 dBm sans dégrader excessivement les données bidirectionnelles transmises simultanément (BER<10-7). / This thesis is devoted to the study of a 10 km long all-optical network dedicated to extend a current cabled seafloor observatory, in order to reach new exploration areas. The research work described in this thesis demonstrates the feasibility of this all-optical link between a remote instrument and a shore station with a single 10 km long optical fiber, which simultaneously transmits the energy required to supply the instrument (several hundred milliwatts) and bidirectional data in real time.The thesis context is presented trough an analysis of the cabled seafloor observatories and of the power-over-fiber. The choice of a single optical fiber and the presence of high optical power complicate the implementation of this all-optical extension, and they cause the appearance of interactions between the optical energy dedicated to the power supply (@1480 nm) and the exchanged data (@1550 nm). Throughout this document, the technological choices are explained and the optical nonlinear effects are described, simulated and analyzed experimentally, such as Raman, Brillouin, and Rayleigh scattering and Amplified Spontaneous Emission (ASE). The proposed all-optical extension has been characterized in static and dynamic regimes with measures of the optical link budget, the Signal-to-Noise Ratio (SNR), and the Bit Error Ratio (BER). The results show the possibility to power the remote instrument with 160 mW, when using a continuous high optical laser source of 33 dBm without huge degradation of the bidirectional data transmitted simultaneously (BER<10-7).

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