• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 92
  • 44
  • 23
  • 9
  • 7
  • 4
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 203
  • 45
  • 45
  • 43
  • 42
  • 41
  • 31
  • 26
  • 26
  • 26
  • 23
  • 21
  • 20
  • 18
  • 18
  • 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.
161

Une approche ontologique pour l'interopérabilité et la composition automatique de services Web : application en astrophysique / An ontologial approach for interoperability and automatic composition of Web services : application to astrophysics

Louge, Thierry 05 July 2017 (has links)
Dans le but d’exploiter au mieux les grandes masses de données hétérogènes produites par les instruments scientifiques modernes de l’astrophysique, les scientifiques ont développé le concept d’Observatoire Virtuel (OV). Il s’agit d’une architecture orientée services, qui a pour objectif de faciliter l’identification et l’interopérabilité des données astrophysiques. Malgré le développement et les avancées permises par l’OV dans l’exploitation de ces données, certains objectifs sont partiellement atteints notamment l’interopérabilité, la sélection de services et l’identification de services connexes, etc. Par ailleurs, l’ergonomie des outils à la disposition de l’utilisateur final reste perfectible. De même l’utilisation actuelle des ressources de l’OV, s’appuyant sur des compétences humaines, gagnerait à être automatisée. Les services de données astrophysiques n’étant pas tous inscrits dans l’OV, il serait aussi souhaitable pour permettre une utilisation plus large de ces outils, qu’ils s’appuient également sur des services disponibles en-dehors de l’OV. En vue d’automatiser l’utilisation des ressources en ligne, les sciences de l’information travaillent depuis 2001 à l’élaboration du Web sémantique. Cette évolution apporte au Web des capacités de raisonnement automatiques, basées sur des algorithmes utilisant une nouvelle forme de description des contenus. Cette nouvelle forme de description sémantique se trouve exprimée dans des représentations informatiques appelées ontologies. Malheureusement, les méthodes actuelles d’élaboration du Web sémantique ne sont pas complètement compatibles avec les services OV qui utilisent des modèles de données, des formats et des protocoles d’accès aux services qui s’éloignent de ceux rencontrés habituellement dans les sciences de l’information. Dans ce contexte, cette thèse décrit une méthodologie générique de composition de services sans état, basée sur la description des services par une ontologie dont la définition est proposée dans ce document. Cette ontologie représente aussi bien des services Web que des services non accessibles par le Web. Elle prend en compte certaines spécificités qui peuvent être rencontrées dans les infrastructures de services préexistantes. L’enrichissement de l’ontologie par des concepts issus de domaines d’application spécifiques pour lesquels il n’existe que peu de représentations ontologiques est également pris en compte. La population de cette ontologie, par des services éventuellement éloignés des standards utilisés habituellement dans les sciences de l’information, est aussi traitée. La méthodologie a été appliquée avec succès dans le cadre de l’astrophysique, et a permis de développer une application Web permettant la composition automatique de services utilisable par un public non averti. / Scientists have developed the Virtual Observatory (VO) concept in order to make the most of the large masses of heterogeneous data produced by the modern scientific instruments of astrophysics. It is a service-oriented architecture, aiming to facilitate the identification and interoperability of astrophysical data. Despite the development and advances made by VO in the exploitation of these data, some objectives are partially such as interoperability, service selection and identification of related services, etc. In addition, the ergonomics of the tools available to the end user can be improved. Similarly, the current use of VO resources, based on human skills, would benefit from being automated. As not all the astrophysical data services are included in the VO, it would also be desirable to allow a wider use of these tools, as they also rely on services available outside the VO. In order to automate the use of online resources, information sciences have been working since 2001 on the development of the Semantic Web. This evolution provides the Web with automatic reasoning abilities, based on algorithms using a new form of content description. This new form of semantic description is expressed in computer representations called ontologies. Unfortunately, the current semantic Web development methods are not fully compatible with VO services that use data models, formats and protocols for accessing services that differ from those typically encountered in information sciences. In this context, this thesis describes a generic methodology for the composition of stateless services, based on the description of services by a global ontology, the definition of which is proposed in this document. This ontology represents both Web services and services that are not accessible via the Web. It takes into account certain specificities that may be encountered in preexisting service infrastructures. The enrichment of the ontology by concepts derived from specific fields of application for which there are only a few ontological representations is also taken into account. The population of this ontology, by services possibly distant from the standards usually used in the information sciences, is also treated. The methodology was applied successfully in the framework of astrophysics, and allowed to develop a Web application allowing the automatic composition of services usable by an uninformed public.
162

Different approaches to determine the composition of the ultra-high energy cosmic rays in the Pierre Auger Observatory / Différentes approches de la détermination de la masse des rayons cosmiques d'ultra haute énergie faite à l'Observatoire Pierre Auger

Blanco Otano, Miguel 12 December 2014 (has links)
L’objectif de cette thèse est d’améliorer la détermination de la masse des rayons cosmiques d’ultra haute énergie faite à l’Observatoire Pierre Auger. Aujourd’hui cette mesure est faite à travers l’utilisation de télescopes à fluorescence qui nécessitent des conditions de luminosité spéciales réduisantle cycle utile à environ 10%. Trois approches différentes sont proposées:La première approche est une nouvelle analyse. Les muons issus des gerbes horizontales sont déviés par le champ magnétique terrestre. Cette déviation modifie l’empreinte au sol des gerbes atmosphériques et est fonction de la longueur de parcours des muons. Un estimateur de Xμmax, leur point de productionmaximum, qui dépend de la masse du primaire peut être construit.La deuxième approche explore la détection du rayonnement radio émis par les gerbes atmosphériques, une technique similaire à la fluorescence mais sans limitation du cycle utile. La détection du rayonnement de Bremsstrahlung moléculaire est revue et explorée de différentes manières.La troisième approche propose un nouveau type de détecteur pour le réseau de surface, ces détecteurs ayant une réponse distincte aux différentes composantes des gerbes atmosphériques : électromagnétique et muonique. La mesure de la composante muonique est aussi un moyen d’accéder à la nature du primaire.La nouvelle analyse semble un outil prometteur qui peut s’appliquer à tout lot de données. La radio-détection en revanche n’apparaît pas comme une alternative compétitive face aux techniques traditionnelles. Le nouveau détecteur offre de belles perspectives et devrait être considéré pour l'équipementdes futurs observatoires. / The motivation of this PhD thesis is to improve the capabilities to determine the mass composition of the ultra-high energy cosmic rays in the Pierre Auger Observatory. The measure of their mass composition is done with the fluorescence technique, that needs special luminosity conditions that reduce the exposure time to about 10% of the time. Three different approaches are proposed.The first approach is a new analysis. Muons in the horizontal showers are deviated by the magnetic field of the Earth. This deflection is related with different characteristics of the extensive air shower that allow the construction of an estimator to obtain an alternative measure of Xμmax, an observable sensitive to the mass of the primary.The second approach is to explore the detection of the radio emission produced in the extensive air showers, a technique similar to the fluorescente one, but without the limitations in the duty cycle. The detection of the Molecular Bremsstrahlung Radiation emission is revised and investigated from different points of view.The third approach is to propose a new surface detector that obtains different responses to the different components of the extensive air shower: electromagnetic and muonic. The access to the muonic component is another way to access to the composition of the primary particle.The new method of analysis proposed appears as a promising tool to be applied in any data set. The technique of the radio detection did not show clear indications of being an alternative to traditional techniques. The new detector represents a promising alternative to be considered in any future ultra-high energy cosmic rays experiment.
163

Propagação e convolução do fluxo primário de raios cósmicos ultra-energéticos segundo a resolução de energia estimada do Observatório Pierre Auger / Propagation and convolution of the ultra-high energy cosmic ray spectrum due to the estimated energy resolution of the Pierre Auger Observatory

Rodrigues, João Paulo Caminha Cascudo 26 February 2007 (has links)
Orientador: Carola Dobrigkeit Chinellato / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-08T01:00:42Z (GMT). No. of bitstreams: 1 Rodrigues_JoaoPauloCaminhaCascudo_M.pdf: 7322384 bytes, checksum: e50136f5ec9d16fff8fd6a15ba64b5f0 (MD5) Previous issue date: 2007 / Resumo: Neste trabalho estuda-se a propagação pelo meio intergaláctico de raios cósmicos ultra-energéticos partindo de fontes com distribuição espacial uniforme, considerando as perdas de energia ocasionadas pela expansão adiabática do universo e pelas interações com a Radiação , Cósmica de Fundo (produção de pares e-e+ e fotoprodução de píons), o que resulta no aparecimento do corte GZK (Greisen-Zatsepin-Kuzmin). A degradação de energia no espectro primário da radiação cósmica que chega ao topo da atmosfera terrestre é então analisada para diferentes redshifts das fontes injetoras. São utilizadas simulações de Monte Carlo bem como uma abordagem analítica, com a posterior comparação dos resultados obtidos em cada método. Uma vez conhecido o fluxo propagado, é feita uma estimativa da forma da resolução de energia do Observatório Pierre Auger, com a decorrente convolução desta resolução com o fluxo propagado, novamente utilizando-se ambos os métodos. Os resultados mostram que o corte GZK pode se mostrar severamente atenuado no fluxo convoluído, o que dificulta a sua constatação experimental / Abstract: In this work, we study the propagation of Ultra-High Energy Cosmic Rays (UHECR) which are injected into the intergalactic medium by sources with flat spatial distribution for several redshifts. The energy spectrum of UHECR observed on the Earth is directly influenced by the energy losses due to both the adiabatic expansion of the universe and interactions with the Cosmic Microwave Background radiation (e-e+ pair production and photoproduction of pions), which cause the so-called Greisen-Zatsepin-Kuzmin (GZK) cutoff. We perform Monte Carlo simulations and also consider a semi-analytical approach and compare the results obtained by each method. Once the propagated primary flux is known, we make a simple estimate of the shape of the Pierre Auger Observatory energy resolution. This resolution is folded with the propagated primary flux again utilizing both methods. The results show the GZK cutoff may be severely smeared and might not be detected as sharp as predicted. / Mestrado / Teorias Especificas e Modelos de Interação ; Sistematica de Particulas ; Raios Cosmicos / Mestre em Física
164

Comparação entre produção de múons nos chuveiros atmosféricos extensos observados no Observatório Pierre Auger e nos detetores do experimento CMS do CERN, a partir de colisões próton-próton / Comparison between muon production in extensive air showers observed at Pierre Auger Observatory and at the detectors of CMS experiment at CERN, from proton-proton colisions

Moreno, Thiago Victor, 1988- 24 August 2018 (has links)
Orientador: José Augusto Chinellato / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-24T07:17:25Z (GMT). No. of bitstreams: 1 Moreno_ThiagoVictor_M.pdf: 9704369 bytes, checksum: 4998048904230625e6cb929460a8f975 (MD5) Previous issue date: 2014 / Resumo: Neste trabalho o programa CORSIKA foi utilizado para gerar eventos de colisão próton-próton e chuveiros atmosféricos extensos com partícula primária sendo próton ou ferro. Como modelo de interações hadrônicas usou-se o EPOS LHC, QGSJET 01c, QGSJET II-4 e SIBYLL 2,1. As colisões p-p foram simuladas com energia igual a 7 TeV no referencial centro de momenta e foi estudada a distribuição de multiplicidade de hádrons carregados e a densidade em pseudorapidez. Comparando estes observáveis com dados do CMS escolheu-se os modelos que melhor reproduzissem os dados para posteriormente, simular chuveiros atmosféricos extensos. Estes chuveiros foram gerados com partícula primária de energia igual a 1019eV no referencial do laboratório. Observou-se a densidade de múons na altitude do Detetor de Superfície do Observatório de raios cósmicos Pierre Auger. O objetivo é estudar a possibilidade de usar esta densidade para sondar modelos de interações hadrônicas e identificar a partícula primária dos eventos detetados pelo Observatório Pierre Auger / Abstract: In this work CORSIKA program was used to generate events from proton-proton collision and extensive air showers with primary particle being proton or iron. The hadronic interaction models used was EPOS LHC, QGSJET 01c, QGSJET II-4 and SIBYLL 2,1. The p-p collisions were simulated with energy equal to 7 TeV in the center of momenta reference system and the charged hadron multiplicity and the pseudorapidity density was studied. Comparing this with data collected by the CMS detector at the LHC it was chosen the best models to generate air showers. The extensive air showers were generated with primary particle energy equal to 1019 eV in the laboratory frame. It was observed the muon density in the altitude of the Surface Detector of the Pierre Auger Observatory. The objective is to study the possibility of using this density to probe the model and the primary particle of the events detected by the Pierre Auger Observatory / Mestrado / Física / Mestre em Física
165

Desenvolvimento de habilidades de leitura em alunos do 8 ano

Sílvia Aparecida Moreira Lima 14 August 2014 (has links)
Esta pesquisa tem como tema o desenvolvimento das habilidades de leitura nos alunos do 8 ano/7 série de uma escola no interior do estado de São Paulo. Após a análise dos resultados do Sistema de Avaliação de Rendimento Escolar do Estado de São Paulo SARESP do ano de 2012 e da Avaliação de Aprendizagem em Processo AAP, aplicada pela Secretaria da Educação do Estado de São Paulo (SEESP) em 2012 e em 2013, verificou-se a necessidade de um trabalho mais sistemático para que os alunos ampliassem sua competência leitora de diferentes gêneros discursivos. O objetivo geral de pesquisa foi contribuir para o desenvolvimento de habilidades de leitura de alunos do ensino fundamental por meio da reflexão sobre as exigências do SARESP e as possibilidades e benefícios de atividades de leitura desenvolvidas nas aulas de Língua Portuguesa de duas salas de 7 série/8 ano de uma escola da Rede Estadual de Ensino do Estado de São Paulo. Tal objetivo encontrou respaldo no projeto OBSERVATÓRIO/UNITAU 2011-2014: `Competências e habilidades de leitura: da reflexão teórica ao desenvolvimento e aplicação de propostas didático-pedagógicas, n23038010000201076, financiado por CAPES/INEP. Especificamente, os objetivos da pesquisa são: 1) Analisar os resultados dos alunos de 6 série/7 ano de uma escola da Rede Estadual de Ensino do Estado de São Paulo na prova de Língua Portuguesa do SARESP 2012 e na AAP 2013, com os mesmos alunos já na 7 série/8 ano; 2) Definir um plano de ação para o desenvolvimento das habilidades de leitura em que esses alunos mostraram mais dificuldades; 3) Desenvolver esse plano de ação em duas salas de 7série/8 ano da escola, durante o ano letivo de 2013, e refletir sobre esse trabalho. Teoricamente, esta pesquisa se baseia na concepção sociocognitiva de leitura, na concepção bakhtiniana de linguagem e gênero discursivo, no conceito de sequência didática proposto por Dolz; Noverraz e Schneuwly (2004, p. 97). Os documentos oficiais sobre a Prova Brasil (BRASIL, 2008) e o SARESP serão utilizados para contextualização das diretrizes educacionais vigentes. Esta pesquisa se desenvolveu metodologicamente por: 1) uma análise qualitativa dos resultados do SARESP 2012 e da AAP 2013; 2) uma pesquisa-ação para o desenvolvimento de um plano de ação focado em habilidades de leitura dos alunos de duas salas de 7série/8 ano. Essas habilidades foram trabalhadas por meio de sequências didáticas de leitura dos gêneros discursivos Tira, Crônica, Fábula e Memórias Literárias, Propaganda social e Propaganda de produtos, a partir de coletâneas de textos desses gêneros. Ao final da etapa de leitura de cada gênero, os alunos realizaram atividades de verificação no formato de questões de múltipla escolha, com características semelhantes às questões da Prova SARESP. Os resultados evidenciaram que, com a prática de leitura sistematizada por sequências didáticas, os alunos se apropriam de características dos gêneros discursivos bem como de estratégias de leitura que contribuem muito para o desenvolvimento de habilidades leitoras. As avaliações realizadas após cada etapa desta pesquisa-ação comprovaram isso. Conclui-se que o trabalho de leitura seguindo sequências didáticas e utilizando diferentes gêneros discursivos é o caminho para desenvolver nos alunos as habilidades de leituras exigidas para que eles sejam leitores proficientes. / The theme of this research is the development of reading skills in students of the 8th/7th grade at a school in the interior of the State of São Paulo. After analyzing the results of the 2012 `Sistema de Avaliação de Rendimento Escolar do Estado de São Paulo - SARESP (State of São Paulos Evaluation of Educational Achievement System) - and the 2013 `Avaliação de Aprendizagem em Processo - AAP (Assessment of Learning in Process), applied by the Department of Education of the State of São Paulo (SEESP) in 2012 and in 2013, there was a need for a more systematic work for students to extend their reading competence of different speech genres. The overall aim of this research was to contribute to the development of reading skills of elementary school students through reflection on the demands of SARESP and the possibilities and benefits of reading activities in Portuguese Language classes in two 7th/8th grade classrooms of a state school in São Paulo. The goal found support on 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. Specifically, the objectives of the research are: 1) compare the results of the 6th /7th graders in a State School in São Paulo in the Portuguese language test of the 2012 SARESP and the 2013 AAP to their results in the 7th/ 8th grade ; 2) Set an action plan for the development of the reading skills these students showed more difficulties in; 3) develop the plan of action in two rooms of grade 7th / 8th grade, during the school year of 2013 and reflect on this work. Theoretically, this research is based on the socio-cognitive conception of reading, on Bakhtins conception of language and speech genre and on the concept of didactic sequence proposed by Dolz; Noverraz and Schneuwly (2004, p. 97). Official documents on the `Prova Brasil (BRAZIL, 2008) and SARESP will be used to contextualize the current educational guidelines. This research is methodologically developed by: 1) a qualitative analysis of the results of the 2012 SARESP and the 2013 AAP ; 2) an action research to develop an action plan focused on the reading skills of students in two 7th /8th grade classrooms. These skills were worked through teaching reading sequences with the speech genres: Strips, Chronicles, Fables and Literary Memoirs, Social Advertising and Advertising of Products, from collections of texts in these genres. At the end of each reading stage of a given genre, students performed verification activities using multiple choice questions, with questions similar to SARESPs questions. The results showed that with the systematic practice of reading using didactic sequences, students understand and learn the characteristics of speech genres and reading strategies that contribute greatly to the development of reading skills. The evaluations performed after each step of this action research have proven that. We conclude that the work of reading following teaching sequences and using different speech genres is the way to develop student‟s required reading skills so that they become proficient readers .
166

Quel est l’apport d’un observatoire photographique pour la protection et la mise en valeur des paysages : le cas des lanières agricoles de la MRC de Memphrémagog

Gauthier, Karl 03 1900 (has links)
En 1986, la MRC de Memphrémagog avait mandaté la firme SOTAR pour procéder à une première caractérisation des paysages d’intérêt (SOTAR, 1986) soit, au sens de la Loi sur l’aménagement et l’urbanisme, les territoires d’intérêt patrimonial, esthétique et culturel. Le mandat avait entre autres conduit à une documentation photographique de ces paysages. Ainsi, quelque 600 diapositives révélant les éléments constitutifs des paysages qui participaient à son caractère distinctif sont issues de cette étude. Informée de l’existence de ce fonds, la MRC, en partenariat avec l’Université de Montréal, s’est dite intéressée à mettre en place un observatoire photographique des paysages afin de définir l’apport de cet outil pour comprendre et de documenter l’évolution de ses paysages d’intérêt. Suivant la méthode générale des observatoires photographiques des paysages (Guittet, 2016), un retour sur près de 60 sites a été effectué et près de 48 rencontres ont été menées auprès d’acteurs du territoire en ayant pour objectif de comprendre les dynamiques sous-jacentes aux transformations observées. Le présent mémoire s’arrime à cette initiative en s’intéressant aux sites contenus à l’intérieur des lanières agricoles identifiées par l’étude de la SOTAR en 1986. À travers l’analyse de 16 sites et la rencontre de 20 participants, l’étude témoigne de l’effacement progressif des paysages des lanières. Le retrait de l’agriculture sur certaines portions du territoire aura contribué à la disparition de granges, à la fermeture de champs visuels et à l’arrivée d’une nouvelle population constituée de non-agriculteurs. Cette étude aura également permis de mieux définir l’importance de la compréhension du contexte social dans la transformation des paysages. / In 1986, Memphrémagog Regional County Municipality (MRCM) mandated SOTAR, an urban planning firm, to characterize landscapes of special interests (SOTAR, 1986) as defined in Quebec Act respecting land use planning and development. An extensive photographic library was collected during the 1986 mandate. This exceptional database of 600 slides allows a description of the landscape elements contributing to the distinctive character of the MRCM. Informed about the potential benefits of the photographic database, MRCM instituted, in partnership with the University of Montreal, a landscape photographic observatory to define how the observatory can be use to understand and document the evolution of landscapes of interest. The present master’s thesis analyses the evolution of the sites contained in the agricultural strips identified in the 1986 SOTAR study. The analysis was conducted using the general method for photographic observatories (Guittet 2016). Data for the analysis was obtained from 16 sites and interviews with 20 rural stakeholders. The analysis documents the progressive disappearance of agricultural strips. The decrease in farming activities in portions of the territory led to the disappearance of barns, a restriction in visual perspective and the arrival of non-farming population. The study highlights the importance of understanding the social context in the transformation of rural landscapes.
167

Gravitational Waves Spectrometry in Space with a Hong-Ou-Mandel Interferometer

Jacinto de Matos, Clovis 13 October 2021 (has links)
In der vorliegenden Dissertation wird ein neues experimentelles Konzept zur Durchführung von Gravitationswellendetektion und Spektrometrie mit einem Hong-Ou-Mandel (HOM) Interferometer im Weltraum untersucht. Dabei wird das Rauschbudget des Instruments bewertet. Die grundlegenden experimentellen Anforderungen werden berechnet. Es wird gezeigt, dass die Leistung und Wellenlänge der verschränkten Photonenquelle, zusammen mit der Winkelgenauigkeit der Messung der Photonenpolarisationsdrehung, die Haupteinschränkungen bilden, um die Art der Gravitationswellenquellen zu bestimmen, die das Ziel von HOM - Gravitationswellenspektrometern sein würden. Die derzeit verfügbaren pW-Leistungen mit typischen Photonenfrequenzen in der Größenordnung von 1014 Hz (sichtbarer - UV-Anteil des optischen Spektrums) sind völlig ungeeignet, was die erforderliche Detektionszeit für eine der Gravitationswellenquellen betrifft, die derzeit von bodenund raumgestützten Gravitationswellendetektoren anvisiert werden. Der Betrieb des HOM-Interferometers als GW-Spektrometer wird mit einem numerischen Modell veranschaulicht, das die von LIGO am 14 September 2015 (GW150914-Ereignis) aufgezeichneten Gravitationswellendehnungsdaten verwendet. Unter der Annahme einer Winkelgenauigkeit von μrad für die Messung der Polarisationsdrehung von Photonen könnten diese Messungen nur mit Armlängen des HOM-Interferometers in der Größenordnung von 10.000 km (nur im Weltraum erreichbar, wenn wir keine optischen Kavitäten verwenden) und unter Verwendung von verschwänkten Photonenquellen von etwa 1 W Leistung durchgeführt werden, die verschränkte Photonen mit Wellenlängen im Radiowellenbereich des elektromagnetischen Spektrumserzeugen, (10 MHz), und unter Verwendung von Photodetektoren mit minimaler Detektionszeit für einzelne Photonen und minimaler detektierbarer Leistung, die weit von den Möglichkeiten der gegenwärtigen Photodetektortechnologie entfernt sind. Auch die erforderliche Präzision der Uhrensynchronisation, um die Koinzidenz- Zählgeschichte zu erfassen, ist noch ange nicht erreicht. Obwohl die Technologie zur Herstellung der erforderlichen verschränkten Photonenquellen, Photodetektoren und Uhrensynchronisationsgenauigkeit derzeit nicht verfügbar sind, diskutieren wir verschiedene Missionsszenarien zur Implementierung eines großarmigen HOMInterferometers.:Contents 1 Introduction 1 2 Gravitational waves and their measurement 7 2.1 Theory of general relativity in a nutshell . . . . . . . . . . . . . . . . 8 2.2 On the physical nature of gravitational waves . . . . . . . . . . . . . 13 2.2.1 Effect of gravitational waves on the test masses of a detector . 15 2.2.2 Estimation of gravitational wave’s amplitude . . . . . . . . . . 18 2.2.3 Gravitational radiation luminosity and cross section of the Hydrogen atom to GWs . . . . . . . . . . . . . . . . . . . . . 21 2.3 Measuring cosmic distances with GW astronomy . . . . . . . . . . . . 25 2.4 Influence of gravitational waves on photon’s polarization . . . . . . . 28 2.4.1 Effect of gravitational waves on the parallel transport of photon’s polarization four-vector - revisited . . . . . . . . . . . . 29 2.4.2 Effect of primordial gravitational waves on the polarization of the cosmic microwave background . . . . . . . . . . . . . . . 36 2.4.3 Gravitomagnetic Faraday effect . . . . . . . . . . . . . . . . . 40 2.5 Michelson type gravitational wave antennas . . . . . . . . . . . . . . 41 2.6 Rough estimation of the sensitivity and cross section of Michelson type detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 3 Interaction of gravitational waves with Hong-Ou-Mandel interferometers 47 3.1 Fundamental nature of quantum entanglement in brief . . . . . . . . 47 3.2 Why a HOM interferometer to detect GWs? . . . . . . . . . . . . . . 50 3.3 Quantum mechanics of Hong-Ou-Mandel interferometers . . . . . . . 54 3.4 Principle of gravitational waves detection with a Hong-Ou-Mandel interferometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 3.5 Instrument noise budget . . . . . . . . . . . . . . . . . . . . . . . . . 68 3.6 Basic experimental requirements for HOM based gravitational waves detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 4 Gravitational waves spectrometry with a Hong Ou Mandel interferometer in space 77 4.1 Principles of gravitational waves spectrometry with a Hong-Ou-Mandel interferometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 4.2 Hong-Ou-Mandel spectrometer in geostationary orbit . . . . . . . . . 93 4.3 Hong-Ou-Mandel spectrometer scanner in space . . . . . . . . . . . . 95 5 HOMER mission scenarios for gravitational waves spectrometry - basic design requirements 97 5.1 HOMER mission design analysis . . . . . . . . . . . . . . . . . . . . . 98 5.1.1 HOMER GEO mission . . . . . . . . . . . . . . . . . . . . . . 99 5.1.2 HOMER ground-GEO mission . . . . . . . . . . . . . . . . . . 105 5.1.3 HOMER scanner mission . . . . . . . . . . . . . . . . . . . . . 106 5.2 Influence of earth gravitomagnetism on photon polarization . . . . . 106 5.3 Payload design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 5.4 Spacecraft design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 5.5 Summary of HOMER mission requirements . . . . . . . . . . . . . . 120 6 Outlook and conclusions 129 6.1 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 6.1.1 HOM gravitational wave detector with optical cavities . . . . 129 6.1.2 Bright entangled heralded photon sources . . . . . . . . . . . 130 6.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 7 ANNEX: Detailed derivation of gravitational waves and gravitoelectric and gravitomagnetic fields 137 7.1 Weak gravitational fields . . . . . . . . . . . . . . . . . . . . . . . . . 137 7.2 General relativity for the practical physicist . . . . . . . . . . . . . . 138 7.3 Gravitational wave equation . . . . . . . . . . . . . . . . . . . . . . . 144 7.4 Gravitoelectromagnetic split of spacetime . . . . . . . . . . . . . . . 145 7.4.1 Gravitational scalar potential . . . . . . . . . . . . . . . . . . 147 7.4.2 Gravitomagnetic vector potential . . . . . . . . . . . . . . . . 147 7.4.3 Space curvature . . . . . . . . . . . . . . . . . . . . . . . . . . 149 7.5 Maxwell-type gravitational equations . . . . . . . . . . . . . . . . . . 151 7.6 Gravitomagnetic waves . . . . . . . . . . . . . . . . . . . . . . . . . . 155 7.7 The equations of motion in the weak field approximation . . . . . . . 156 7.8 Production of gravitational radiation . . . . . . . . . . . . . . . . . . 160 Bibliography 163
168

Numerické metody zpracování obrazů z kosmické sondy NASA SDO / Numerical methods of image processing from NASA's SDO space probe

Meduňa, Tomáš January 2020 (has links)
Tato práce se zabývá zpracováním snímků Slunce pořízených kosmickou sondou SDO na různých vlnových délkách a vizualizací výskytu třikrát ionizovaného uhlíku C IV jejich vhodným složením. V práci jsou uvedeny základní informace o Slunci a jeho atmosféře, dále je shrnuta potřebná teorie a možné postupy vizualizace, které jsou následně vyhodnoceny a porovnány. Součástí je i vytvořený program pro snadnou tvorbu snímků vizualizujících uhlík C IV.
169

Spršky kosmického záření s anomálními podélnými profily / Cosmic ray showers with anomalous longitudinal profile

Blažek, Jiří January 2014 (has links)
Title: Cosmic Ray Showers with Anomalous Longitudinal Profile Author: Jiří Blažek Department: Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University Supervisor: RNDr. Petr Trávníček, Ph.D., Institute of Physics ASCR Abstract: The aim of this work was to study high-energy cosmic ray showers with anomalous longitudinal profiles generated by Monte-Carlo simulation and subse- quently use the acquired analysis techniques on results from the Pierre Auger Observatory (PAO) in Argentina. Firstly, a short introduction of various de- scriptions of the extensive air showers was given. Then a systematic analysis was performed on approx. 7 × 105 simulated showers with three different tech- niques. A brief explanation of the functionality of the PAO was given, then the importance of monitoring the immediate state of the atmosphere using the Shoot- the-Shower program was elucidated and the FRAM telescope was described in detail. FRAM enabled an identification of showers with a clear atmospheric back- ground, this sample of showers was then analyzed and several interesting events warranting a further study were chosen. Keywords: Pierre Auger Observatory, Extensive Air Showers, Chemical Compo- sition, Anomalous Longitudinal Profile, Gaisser-Hillas Function
170

Studium interakcí částic kosmického záření při extrémně vysokých energiích / Study of Interactions of Cosmic Rays at Ultra-high Energies

Nečesal, Petr January 2015 (has links)
This thesis is dedicated to study of interactions of utra-high energy cosmic rays using measured data from the Pierre Auger Observatory, automatic alarm system called Shift Guard and analysis of correlation of temperature and detector response. The Pierre Auger Observatory is the largest experiment to study ultra-high energy cosmic rays. The assumed relation between temperature and fluorescence detector response is studied together with descriptive temperature analysis, which shows that the air-conditioning system is not able to stabilize temperature enough. The temperature influence on camera response is investigated in order to measure the calibration correction factor. Shift Guard - the alarm system dedicated to protect fluorescence detectors and data taking is introduced and its functionality is described. The alarm system informs shifters about some events and situations that can endanger detector or deteriorate data quality. The basic parameters and alarm system logic are described together with light and sound signals. The discrepancy between measured and predicted number of muons at ground level calculated by EAS generators is showed and possible sources of this disagree- ment are studied. The result of massive dark photons decay in EAS as one of exotic muon source is presented. The analysis...

Page generated in 0.0764 seconds