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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.
21

Étude du pouvoir de discrimination des primaires initiant les grandes gerbes atmosphériques avec des réseaux de détecteurs au sol : analyse des rayons cosmiques de ultra haute énergie détectés à l’observatoire Pierre Auger, Estimation des performances pour la detection de gamma de très haute énergie du future observatoire LHAASO / Study of the discriminatory potential of primary particles initiating large air showers with arrays of ground detectors : analysis of ultra high-energy cosmic rays detected at the Pierre Auger observatory, Performance of very-high-energy gamma rays detection at the future LHAASO observatory

Martraire, Diane 20 October 2014 (has links)
Depuis plus d’un siècle, les rayons cosmiques d’ultra-haute énergie (RCUHE), ayant une énergie supérieure à 1018 eV, continuent d’entretenir le mystère : Quelle est leur composition ? D’où viennent-ils ? Comment atteignent-ils de telles énergies ? Ces particules chargées, suffisamment énergétiques pour atteindre la Terre, forment des gerbes de particules secondaires via leurs interactions avec l’atmosphère dont le développement est caractéristique de la nature de la particule primaire. L’observatoire Pierre Auger, avec sa structure hybride et son gigantesque réseau de détecteurs peuvent apporter des réponses. L’étude de la composition des RCUHEs a été étudiée avec le réseau de surface de l’observatoire Pierre Auger. Cette dernière est cruciale à la fois pour comprendre les interactions hadroniques, qui constituent le développement des gerbes, et pour identifier leurs sources. Cela peut également aider à comprendre l’origine de la coupure spectrale aux plus hautes énergies : s’agit-il de la coupure GZK ou à l’extinction des sources. Toutes ces raisons motivent la première partie de la thèse, à savoir la mise en place d’une méthode permettant d’extraire la composante muonique des gerbes atmosphériques et d’en déduire la composition. Les résultats de cette méthode montrent une dépendance de la composition avec la distance à l’axe de la gerbe, qui pourrait aider à améliorer les modèles hadroniques. Dans les conditions actuelles du réseau de surface, l’identification de la composante muonique présente des limites.La seconde partie est consacrée au nouvel observatoire en Chine, LHAASO. Ce projet s’intéresse à l’étude des gammas supérieurs à 30 TeV, qui signeraient l’accélération de proton dans la galaxie, donnant ainsi des informations indirectes sur les rayons cosmiques. D’autre part, l’observatoire vise à étudier les rayons cosmiques entre 10 TeV et 1 EeV, région où le spectre en énergie présente une rupture. Cette région nécessite de pouvoir discriminer les gammas des rayons cosmiques. A ce titre, l’un des détecteurs de LHAASO, le KM2A, a été simulé et son pouvoir de discrimination gamma/hadron évalué. / During the past century, ultra-high-energy cosmic rays (UHECR), those with an energy larger than 1018 eV, remain as a mystery: What are cosmic rays? Where do they come from? How do they attain their huge energy? When these charged particles strike the earth's atmosphere, they dissipate their energy by generating a shower of secondary particles whose development is significantly different depending on the nature of the primaries. The Pierre Auger observatory, with its hybrid structure and huge size network of ground detectors, can shed some light into these questions.The study of the composition of UHECR was performed with the Pierre Auger apparatus. This is crucial both to understand the hadronic interactions, which govern the evolution of showers, and to identify their sources. It can help to understand the origin of the energy spectrum cut-off: is it the GZK cut-off or the exhaustion of sources? These reasons motivate the first part of this thesis: the development of a method to extract the muonic component of air showers and deduce the implications on the composition of UHECR at the Pierre Auger observatory. The results of this method show a dependence of the composition with the distance to the axis of the shower, which could help to improve the hadronic models. The determination of the muon component is limited by the surface detector setup.The second part is devoted to the new observatory in China, LHAASO. This project focuses on the study of gamma rays with an energy higher than 30 TeV, which probe the acceleration of protons in the galaxy, providing indirect information on cosmic rays. Moreover, the observatory studies cosmic rays between 10 TeV and 1 EeV, one of the regions where the energy spectrum presents a break. This region requires the ability to discriminate gamma rays and cosmic rays. For this reason, one of the detectors of LHAASO, the KM2A, was simulated and its power of discrimination gamma/hadron evaluated.
22

Precise nuclear data of the 14N(p,gamma)15O reaction for solar neutrino predictions

Wagner, Louis 11 April 2019 (has links)
The 14N(p,gamma)15O reaction is the slowest stage of the carbon-nitrogen-oxygen cycle of hydrogen burning and thus determines its reaction rate. Precise knowledge of its rate is required to improve the model of hydrogen burning in our sun. The reaction rate is a necessary ingredient for a possible solution of the solar abundance problem that led to discrepancies between predictions of the solar standard model and helioseismology. The solar 13N and 15O neutrino fluxes are used as independent observables that probe the carbon and nitrogen abundances in the solar core. This could settle the disagreement, if the 14N(p,gamma)15O reaction rate is known with high precision. After a review of several measurements its cross section was revised downward due to a much lower contribution by one particular transition, capture to the ground state in 15O. The evaluated total relative uncertainty is still 7.5%, in part due to an unsatisfactory knowledge of the excitation function over a wide energy range. The present work reports experimentally determined cross sections as astrophysical S-factor data at twelve energies between 0.357 - 1.292 MeV for the strongest transition, capture to the 6.79 MeV excited state in 15O with lower uncertainties than before and at ten energies between 0.479 - 1.202 MeV for the second strongest transition, capture to the ground state in 15O. In addition, an R-matrix fit is performed to estimate the impact of the new data on the astrophysical relevant energy range. The recently suggested slight S-factor enhancement at the Gamow window could not be confirmed and differences to previous measurements at energies around 1 MeV were observed. The present extrapolated zero-energy S-factors are S_6.79(0) = (1.19+-0.10) keV b and S_GS(0) = (0.25+-0.05) keV b and they are within the uncertainties consistent with values recommended by the latest review. / Die 14N(p,gamma)15O Reaktion ist die langsamste Phase im Bethe-Weizsäcker-Zyklus des Wasserstoffbrennens und bestimmt deshalb die Reaktionsrate des gesamten Zyklus. Präzise Werte für die Reaktionsrate sind notwendig um das Wasserstoffbrennen in unserer Sonne besser zu verstehen. Besonders das Problem widersprüchlicher Ergebnisse aus Vorhersagen des aktuellen Sonnenmodells und helioseismologischen Experimenten könnte durch genauer bekannte 14N(p,gamma)15O Reaktionsraten aufgelöst werden. Dafür soll der solare 13N und 15O Neutrinofluss von den beta+-Zerfällen als direkter Informationsträger über die Häufigkeit von Stickstoff und Kohlenstoff im Sonneninneren genutzt werden. Der für die Berechnung der Häufigkeiten benötigte Wirkungsquerschnitt der 14N(p,gamma)15O Reaktion wurde in einer Evaluation verschiedener Messungen reduziert, da der Anteil des direkten Protoneneinfang mit Übergang in den Grundzustand deutlich weniger zum gesamten Wirkungsquerschnitt beiträgt als zuvor angenommen. Die evaluierte relative Gesamtunsicherheit ist mit 7.5% dennoch hoch, was zu einem großen Teil an ungenügendem Wissen über die Anregungsfunktion in einem weiten Energiebereich liegt. In der vorliegenden Arbeit werden experimentell ermittelte Wirkungsquerschnitte in Form von astrophysikalischen S-Faktoren für zwei Übergänge vorgestellt. Für den stärksten Übergang, den Protoneneinfang zum angeregten Zustand bei 6.79 MeV in 15O, wurden zwölf S-Faktoren bei Energien zwischen 0.357 – 1.292 MeV mit geringeren Unsicherheiten als zuvor ermittelt und für den direkten Übergang in den Grundzustand zehn Werte zwischen 0.479 – 1.202 MeV. Außerdem wurde ein R-Matrix Fit durchgeführt um den Einfluss der neuen Daten auf Extrapolationen zum astrophysikalisch relevanten Energiebereich zu prüfen. Die kürzlich vorgeschlagene Erhöhung des S-Faktors im Gamow-Fenster konnte nicht bestätigt werden und es wurden auch Unterschiede zu bisherigen Messungen im Energiebereich um 1 MeV deutlich. Die neuen extrapolierten S-Faktoren sind S679(0) = (1.19±0.10) keV b und SGS(0) = (0.25 ± 0.05) keV b und sie stimmen mit den von der Evaluation empfohlenen Werten im Rahmen ihrer Unsicherheiten überein.
23

Pohybové programy pro ovlivnění tělesného složení a tělesné zdatnosti seniorů / Motion programmes to influence body composition and physical fitness of seniors

Hráský, Pavel January 2014 (has links)
In this work we focused on the application of physical activity, which aimed to reduce the negative impact of physical deprivation and associated functional and structural changes in the musculoskeletal system. The principal criterion was the diagnosis of the organ systems of the locomotor system, focusing on the muscular system. The subsequent application of appropriate forms of exercise intervention was designed to mitigate the effects of the aging process and functional changes in the body of the senior individual. Finally, we wanted to assess the impact of changes in body composition in its own self- sufficiency and independence of older people and the quality of life of older people in terms of physical and psychosocial aspects. The most significant is the loss of muscle mass, sarcopenia development, increase fat mass with frequent reductions in body weight. The focus of our work and its specific purpose is to clarify the influence of the applied physical interventions. To assess changes in body composition are needed for our work used the method of multi Bioanalysis. Results in body composition in older adults have been evaluated and intra-individual measured data were compared with the general senior population. Kinesiology testing shortened muscle groups was carried out repeatedly to reduce...
24

Phase Analysis and Modeling of Scale Deposition in Steel Tubes

Kuriger, Raymond J. 15 July 2016 (has links)
No description available.
25

Alternativní přístupy přípravy tenké vrstvy nitridu hliníku pomocí metody depozice atomárních vrstev / Alternative approaches for Preparation of AlN Nanolayers by Atomic Layer Deposition

Dallaev, Rashid January 2021 (has links)
Nitrid hliníku (AlN) je slibný polovodivý materiál s velkou mezerou v pásu. Tenké filmy AlN nacházejí uplatnění v různých elektronických a optoelektronických zařízeních. V první řadě je cílem výzkumu prezentovaného v rámci této disertační práce představit nové prekurzory do procesu ALD pro depozici tenkých vrstev AlN. Navrhované prekurzory jsou lepší než tradiční prekurzory buď v nákladové efektivnosti nebo reaktivitě. Část disertační práce je věnována prohloubení porozumění chemickým procesům, které probíhají během a po depozici. V tomto ohledu bylo navrženo pracovní řešení ke zlepšení chemického složení výsledných filmů a ke zmírnění nedostatků, například oxidace. Dalším důležitým aspektem této studie je důkladná analýza fenoménu vodíku v tenkých vrstvách AlN ALD. Vodíkové nečistoty byly zkoumány pomocí přesných a pokročilých technik patřících do skupin analýzy iontovým paprskem (IBA).
26

Kořeny moravské urbanistické struktury / Roots of Moravian Urban Structure

Mohelník, Ladislav Unknown Date (has links)
The thesis has been written on the basis of main architectural concepts and their application in real life within a historical context investigation. Main architectural concepts are represented in a harmony of architectural composition that deals with relations among form, structure and space in the unique art work. Genius loci play very important role in the architectural creation - it represents a special and extra-ordinary urban locality and its architectural value in the historical, geographical and cultural context. The origin of Ostravice village within the historical frame concept of Moravia domain is the topic of this thesis. Other historical documents gave information about Bruneswerde as the Brno Castle. That means Brno Castle had to be founded not in Brno (as it has been consid-ered for many years) but it was located in Beskydy at Ostravice. The sacred city – Civitas Dei had been located in Bruneswerde region in early ages as the centre of European culture, education and spiritual life. Civitas Dei – divine Jerusalem in the transcription of St. Augustine's book De civitate Dei – is not only glorification of God and religious fantasy. It is also one of significant clues for recognition of historical architecture. The depiction of unknown settlement from the book of unde-fined origin is a superb testimony about extinct architectural works. They are legible from cadastral maps. Brno Castle - residence of nobility and power served shelter to St. Vojtěch, St. Prokop, St. Václav and St. Ludmila as it is obvious for the mentioned picture. Three major temples, three com-position axes symbolized by three towers on coins are in analogical relation to Brno triangle of four saints - the Saint family of Brno temples. Powerful ambitions of Brno City principals and clergy are inscribed into the urban structure in the way of composition relations which are legible to them who devoted themselves to the mystery of harmony. The absence of historical continuity affects personal attitudes and also identity of the whole community. The architecture truly reflects the past state of polis and it is eloquent even after its death. The architectural composition relations influence the natural environment for long time, longer than the architectural work existence. The geometric order of Renaissance Brno existence has not been in attention of architects so far. The features were discovered in characteristic paintings by Albrecht Durer. They are evidently secret works of the genius. A meaningful collaborator and follower in the extensive project was also his friend Jan Čert from Brno and lately from Vienna. His noble genealogy played a significant role in history of Silesia and Moravia for centuries. It is tendency to consider him as Austrian or even German architect. It is because of the fact that the genealogy tree of his noble family had roots in Moravia. It is supposed that Durer with Jan Čert´s support created the extraordinarily monumental architectural and urban works in Brno. A remarkable consensus in the urban composition of two squares and transition of traditional urban structure of Ostravice Civitas Dei into the modern Brno is also confirmed due to the identification of noble creators and owners, who were at the foundation, transformation and extinction of elements of the Moravian urban structure.

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