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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.
591

X-ray Study on Supernova Remnants Interacting with Dense Clouds / 濃い分子雲と相互作用する超新星残骸からのX線の研究

Okon, Hiromichi 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第22995号 / 理博第4672号 / 新制||理||1670(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 鶴 剛, 准教授 窪 秀利, 教授 中家 剛 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
592

Etude des rayons cosmiques d'ultra-haute énergie avec l'Observatoire Pierre Auger : de l'extraction du signal à l'interprétation du spectre en énergie / Study of the Ultra-High Energy Cosmic-Rays with the Pierre Auger Observatory : from extraction of signal to interpretation of energy spectrum

Luce, Quentin 24 September 2018 (has links)
L’origine et la composition des rayons cosmiques demeurent, presque un siècle après leur découverte, une question ouverte, certains résultats des expériences de détection des rayons cosmiques se contredisant même, aux énergies supérieures à 10¹⁸ eV. A ces énergies, le flux reçu sur Terre est si faible qu’une détection directe est impossible sur une échelle de temps raisonnable. La collaboration Pierre Auger a ainsi construit dans la Pampa argentine, un observatoire couvrant une surface de 3000 km² afin de déterminer les énergies, les masses et les directions d’arrivée des rayons cosmiques. Les techniques de détection déployées font de l’Observatoire Pierre Auger une référence dans le domaine des Ultra-Hautes Énergies. Durant les trois années de mon doctorat, il m’a été donné l’opportunité d’étudier les méthodes de détection déployées par cette expérience et de m’intéresser spécialement à son détecteur de surface dont l’extraction du signal jusqu’à la reconstruction des directions d’arrivée et des énergies des rayons cosmiques sont présentées dans ce manuscrit avec les optimisations développées, permettant l’établissement du spectre des rayons cosmiques. L’étude de ce spectre, combinée à celle des observables de composition, obtenues par le détecteur de fluorescence, permet son interprétation en terme de masse afin de contraindre les modèles d’accélération et de propagation dans le milieu Galactique ou extragalactique. / The origin and the composition of the cosmic rays, almost one century after their discovery, remain an open question. Results of some experiments dedicated to their detection are even contradicting themselves at energies above 10¹⁸ eV. At these energies, the flux of the cosmic rays reaching the Earth is so low that direct detection is unthinkable in a reasonable time scale. The collaboration Pierre Auger has thus built, in the Argentine Pampa, an observatory covering an area of 3000 km² to determine the energies, masses and arrival directions of cosmic rays. Deployed detection techniques make the Pierre Auger Observatory a reference in the field of Ultra-High Energy. During the three years of my thesis, I had the chance to study the detection methods deployed by this experiment, focusing on its surface detector from the extraction of its signal to the reconstruction of the arrival direction and energy of the cosmic ray, which are presented in this manuscript along with the optimizations developed. The energy spectrum of cosmic rays is then reconstructed. The study of this spectrum, combined with the observables of composition, deduced from the fluorescence detector, allows its interpretation in term of mass. Acceleration and propagation models in Galactic or extragalactic environment can then be constrained by this combined study.
593

Étude et modélisation de l’interaction des particules cosmiques avec les détecteurs cryogéniques de l'astronomie submillimétrique et X / Study and modeling of cosmic ray interaction with cryogenic detectors for submillimeter and X-ray space astronomy

Miniussi, Antoine 05 October 2015 (has links)
Les particules cosmiques sont émises par différentes sources galactiques et sont composées de protons et de noyaux d'hélium. Ces éléments interagissent avec les matériaux et y déposent leur énergie par interaction nucléaire. L'instrument Planck/HFI a observé le ciel depuis l'espace dans le but de cartographier le fond diffus cosmologique. Pour cela, HFI embarque un plan focal refroidit à 100 mK composé de 54 bolomètres. Le flux de particules cosmiques, interagissant avec les composants des détecteurs (thermomètre, grille, wafer), chauffe ponctuellement les capteurs (glitches) ce qui entraine une dégradation du signal scientifique. Leur étude a révélé un autre effet thermique caractérisé par un chauffage global du plan focal de l'ordre du microkelvin, les High Coincidence Events (HCE). Deux familles de HCE ont été isolées dans les données : les rapides, générés par des gerbes de particules secondaires formées dans les couches externes du satellite et interagissant avec l'ensemble de l'instrument HFI ; les lents, généré par la vaporisation d'hélium formant un lien thermique ponctuel entre le plan focal et l'étage à 1,6 K lui faisant face. L'exposition d'une matrice de bolomètres TES à une source de particules α a démontré une réponse similaire mais également des glitches simultanés entre les pixels.Ces recherches démontrent que les particules cosmiques et les gerbes de particules doivent être étudiées afin d'éviter des effets thermiques prédominant. Le développement des prochaines générations de détecteurs, devront ainsi prendre en compte ces interactions indissociables d'une mission spatiale et s'en prémunir. / Cosmic rays are emitted from different galactic sources and consist of protons and helium nuclei. These elements interact with matter and deposit part of their energy by nuclear interaction.The Planck/HFI instrument observed the sky from space to map the Cosmic Microwave Background. For this purpose, HFI has a focal plane cool down to 100 mK and composed of 54 bolometers. The interactions of the cosmic ray flux with the detectors' components (thermometer, grid and wafer) heat up regularly the sensor (glitches) which leads to a degradation of the scientific signal. Studying them revealed another thermal effect characterized by a thermal increase of the entire focal plane up to the microkelvin range, the High Coincidence Events (HCE).Two HCE famillies were separated: the fast ones, generated by cosmic ray showers developed in the external layers of the satellite and interacting with the entire HFI instrument and the slow ones, generated by the vaporisation of helium forming a ponctual thermal link between the focal plane and the 1.6 K stage facing it.Exposure of a TES bolometer matrix to an α particules source showed a similar response but also simultaneous glitches on several pixels. This work demonstrates that cosmic rays and particle showers on next low temperature experiments has to be studied to prevent predominating thermal effects from it. The developpement of futur space experiments will have to take these interactions into account to elimiate them from data.
594

Apologetika křesťanství Teilharda de Chardin / Teilhard de Chardin's apologetics of Christianity

Procházka, Leoš January 2017 (has links)
The thesis "Teilhard de Chardin's apologetics of Christianity" starts with a brief introduction to apologetics and fundamental theology in general, on the basis of Teilhard's thought, presents the main critical comments and addresses the methodological question of the approach to his thinking. In the main part, develops the structure of apologetics from the phenomenological description of the world's evolution, from the particles and animals through the emergence of consciousness and man. This is showed on the basis of the "law of complexity and consciousness", which shows the increase of consciousness with the increase of the complexity. And then, through noogenesis (evolution of the spirit), it reaches the point of Omega. The thesis addresses the question of the legitimacy of such extrapolation and continues to the philosophical deduction of Omega's characteristics, as essentially transcendent, to an entropy independent, attractive and present. From the philosophically introduced point of Omega, seeks to show the possibility of identifying Christ of revelation with the Omega point through the theological reflection, as proof and defense of the truth of Christianity. The thesis tries to critically evaluate the apologetics thus built, to elaborate the philosophical view and to evaluate the...
595

Utilizing Permanent On-Board Water Storage for Efficient Deep Space Radiation Shielding

Gehrke, Nathan Ryan 01 June 2018 (has links)
As space technologies continue to develop rapidly, there is a common desire to launch astronauts beyond the ISS to return to the Moon and put human footsteps on Mars. One of the largest hurdles that still needs to be addressed is the protection of astronauts from the radiation environment seen in deep space. The most effective way to defend against radiation is increasing the thickness of the shield, however this is limited by strict mass requirements. In order to increase the thickness of the shield, it is beneficial to make mission critical items double as shielding material. The human rated Orion spacecraft has procedures in place for astronauts to create an emergency bunker using food and water in the event of a forewarned radiation storm. This can provide substantial support to defend against radiation storms when there is an adequate amount of warning time, however, fails to protect against Galactic Cosmic Radiation (GCR) or Solar Particle Events (SPE) without sufficient warning. Utilizing these materials as a permanent shielding method throughout the mission could be a beneficial alternative to the Orion programs current protection plan to provide constant safety to the crew. This thesis analyzes the effect in the radiation dosage seen by astronauts in the Orion Crew Module through use of on-board water as a permanent shielding fixture. The primary method used to analyze radiation is NASA’s OLTARIS (On-Line Tool for the Assessment of Radiation In Space) program, which enables users to input thickness distributions to determine a mission dosage profile. In addition this thesis further develops a ray tracing code which enables users to import male and female models into the vehicle model to produce gender specific radiation dosage results. The data suggests the permanent inclusion of water as a shielding material provides added support for GCR as well as SPE radiation that can extend the mission lifetime of humans in space.
596

Semidiurnal tidal signature over Collm (51.3N, 13E) in sporadic E layer frequency obtained from FORMOSAT-3/COSMIC GPS radio occultation measurements

Jacobi, Ch., Arras, C, Wickert, J. 17 August 2017 (has links)
We present measurements of sporadic E (Es) layer occurrence frequency from FORMOSAT-3/COSMIC GPS radio occultation measurements at 50°-55°N and compare these with zonal wind shears measured by meteor radar at Collm. Both parameters are, on a diurnal time scale, dominated by a semidiurnal oscillation. According to theory, maximum Es occurrence is expected when the zonal wind shear is negative. This is confirmed by our measurements and analyses. / Es werden Messungen sporadischer E-Schichten (Es) mit Hilfe von FORMOSAT- 3/COSMIC GPS-Radiookkultationsmessungen bei 50°-55°N vorgestellt und mit Analysen des zonalen Windes aus Meteorradarmessungen verglichen. Auf einer Zeitskala bis zu einem Tag ist eine halbtägige Komponente das dominierende Muster. Nach allgemein anerkannter Theorie sollten sporadische E-Schichten bevorzugt bei negativer Scherung des Zonalwindes auftreten. Die hier gezeigten Analysen bestätigen dies.
597

UTILIZING SUPERNOVA REMNANT DYNAMICS AND ENVIRONMENTS TO PROBE CORE-COLLAPSE EXPLOSIONS

John D Banovetz (12557977) 17 June 2022 (has links)
<p> Core-collapse supernovae are among the most consequential astronomical events. They impact galaxy evolution, chemical enrichment of the Universe, and the creation of exotic objects (e.g., black holes and neutron stars). However, aspects of supernovae such as explosion asymmetry and progenitor mass loss are not well understood. Young, nearby supernova remnants are excellent laboratories to uniquely constrain some these fundamental properties. In this thesis, I investigate two nearby oxygen-rich supernova remnants and measure the proper motion of their ejecta to estimate their center of expansions and explosion ages. These properties are important for determining central compact object ‘kick’ velocities, guiding searches for surviving companions, and creating 3D remnant reconstructions. </p> <p><br></p> <p>I estimate the center of expansion and age of two supernova remnants, 1E0102.2-7219 (E0102) and N132D utilizing two epochs of Hubble Space Telescope imaging to measure the proper motion of their ejecta. For E0102, the proper motions show evidence for a nonhomologous expansion, which combined with spectral observations, support the idea that this remnant is expanding into an asymmetric circumstellar environment. Using the new proper-motion derived age and center of expansion, I provide a new ‘kick’ velocity estimate for E0102’s candidate neutron star. For N132D, I measure the proper motion of the ejecta both visually and using a novel computer vision procedure which identifies and measures the proper motions of the knots. I find that N132D’s ejecta are still ballistic, along with evidence of explosion asymmetry. My results represent the first proper-motion derived center of expansion and age of N132D. </p> <p><br></p> <p>Finally, I investigate diffuse interstellar bands observed towards progenitor candidates of core-collapse supernovae to test whether time variability can be a possible probe of the mass loss and surrounding environments of these systems. I find evidence of time variability in diffuse interstellar band carriers located in two of these environments. This is especially unusual as diffuse interstellar bands are normally attributed to the interstellar medium. These findings imply that the sources of these bands are closer to the stellar objects than previously thought and can provide insight into the currently unknown sources of diffuse interstellar bands. </p>
598

Experimentální studium teploty elektronů a iontů v impaktovém plazmatu / Experimental study of electron and ion temperatures in impact plasmas

Kočiščák, Samuel January 2021 (has links)
Title: Experimental study of electron and ion temperatures in impact plasmas Author: Samuel Kočiščák Department: Department of Surface and Plasma Science - DSPS Supervisor: doc. RNDr. Jiří Pavlů, Ph.D., DSPS Abstract: In-situ analysis of a hypervelocity grain impact is a complex discipline, making use of multiple physical phenomena. An important one, if not the most important one, being a dust impact ionisation. Future experiments could benefit substantially from better understanding of the phenomenon. The goal of this work was a study of the impact ionisation per-se, with the objective: to experimentally determine the effective temperatures of post-impact charged ejecta. Importance of this parameter is obvious, although different approaches scarcely ever report similar results. Our way was the analysis in a retarding potential analyzer. Firstly, large data set of laboratory data from dust accelerator was analyzed, secondly a Monte Carlo study of the results and the analyzer itself was performed. Lastly, recommendations for future in-situ experiments are provided based on our results. Keywords: impact plasmas cosmic dust impact ionization
599

A new model and tests of the JEM-EUSO Balloon pathfinders Fresnel optics

Díaz Damián, Abraham Neftali January 2016 (has links)
EUSO-Balloon and EUSO-SPB are balloon borne pathfinder projects designed to val- idate the techniques of the JEM-EUSO space observatory. They are nadir pointing UV telescopes that use experimental experimental Fresnel optics to detect the ultravi- olet emission of Extensive Air Showers (EAS) induced by Ultra High Energy Cosmic Rays (UHECR) in the atmosphere. EUSO-Balloon was launched by the balloon di- vision of CNES (the french space agency) from Timmins, Ontario, Canada in 2014. Despite the success of the mission the performance of the optics was lower than what it was originally modeled and led to many doubts regarding the understanding of the optics and fresnel lenses themselves. This thesis explores three parameters proposed to explain the reduction in eciency of the system which were not simulated in the original characterization: the rounded valleys in the Fresnel lens grooves created by the tool peak radii, scratches on the surface of the lenses and the surface roughness of the fresnel lenses. These parameters were simulated and results show that they show a reduction in performance which approximates more the characterization measure- ments but still do not match exactly, leaving room for further analysis. EUSO-SPB1 is the successor of EUSO-Balloon with a launch planned in 2017 from Wanaka, New Zealand. The results of the first phase of the optics characterization campaign is pre- sented in this work. The results indicate that the optics performance is similar to that of EUSO-Balloon and require further understanding. / <p>Thesis defended in Toulouse, France as part of the SPACEMASTER programme.</p>
600

Modeling Solar Cosmic Ray Transport within the Ecliptic Plane / Modellierung des Transports solarer energiereicher Teilchen in der Ebene der Ekliptik

Lampa, Florian 04 April 2012 (has links)
Since six decades the understanding of interplanetary propagation of solar flare accelerated, energetic charged particles in the inner heliosphere has not yet achieved sufficient closure. The essential mechanisms acting on these charged particles, which perform helical orbits along the large-scale magnetic field lines as probes, have already been identified. However, in particular the impact of the three-dimensional, small-scale magnetic fluctuations on the particles' trajectories has not yet been fully understood. These superimposed disturbances are expected to interact with the charges via resonance principle – leading to both field-aligned scattering and diffusive cross-field displacements of the particles' guiding center. Since numerical solutions and known theoretical formulations have failed to verify the measurements so far, Ruffolo's equation – which is a special formulation of the Fokker-Planck equation – is applied to take account of the current knowledge about field-parallel transport; The partial differential equation is extended to a two-dimensional model within the ecliptic plane by a spatial diffusion term perpendicular to the field. We assume an idealized Archimedean field neither with polarity changes nor large-scale disturbances such as traveling magneto-hydrodynamic shock waves or magnetic clouds. The transport equation is solved numerically by finite differences. For typical ratios of perpendicular to parallel diffusion coefficient as deduced from theory, various fits have been found in good agreement with multi-spacecraft measurements. Some events and the occurrence of observed sudden flux drop-outs suggest that scattering on magnetic field irregularities significantly varies from one flux tube to another. In addition to the already existing, but sparse set of particle observations at different positions, once the current solar minimum has passed by, a new set will be available from the recently launched STEREO satellites.

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