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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.
71

Laços de Wilson supersimétricos na correspondência AdS/CFT / Supersymmetric Wilson loops in the AdS/CFT correspondence

Dhyan Victor Hiromitsu Kuraoka 29 May 2013 (has links)
O objetivo desta dissertação é revisar os operadores laços de Wilson no contexto da correspondência AdS/CFT. Estes operadores, presentes em qualquer teoria de calibre, são importantes por nos fornecer um parâmetro de ordem para a transição de fase confinante/desconfinante. Além disso, eles são particularmente importantes no estudo da correspondência AdS/ CFT pois: i) Eles nos dão, em alguns casos, resultados exatos graças ao fato de poderem ser localizados em um modelo de matrizes, desta forma nos permitindo fazer testes altamente não triviais da correspondência; ii) Eles são os objetos da teoria de calibre que são duais as cordas propagando no interior do espaço, nos dando um rico dicionário entre quantidades no interior (AdS) e na borda do espaço (CFT). Depois de revisarmos os laços de Wilson em teorias de calibre e a correspondência Ads/CFT, introduziremos a definição dos laços de Wilson supersimétricos 1/2 BPS. Calcularemos eles para o caso de um acoplamento fraco e para qualquer outro valor da constante de acoplamento usando técnicas de modelos de matrizes. Finalmente, compararemos nossos resultados com computações de superfícies minimais no interior do espaço, encontrando uma concordância perfeita. / The aim of this thesis is to review Wilson loop operators in the contexto f the AdS/CFT correspondence. These operators, wich are present in any gauge theory, are important because they furnish an order parameter for confinement/deconfinement phase transitions. Besides this, they are particularly relevant in the study of the AdS/CFT correspondence because: i) they allow, in some cases, for exact results thanks to localization to matrix models and make it possible to perform highly non-trivial tests of the correspondence; ii) they are the gauge theory objects dual to strings propagating in the bulk of the space and give a rich dictionary between bulk (AdS) and boundary (CFT) quantities. After reviews of Wilson loops in gauge theories and of the Ads/CFT correspondence, we will introduce the definition of 1/2 BPS supersymmetric Wilson loops, we will compute them at weak coupling and then at any order in the coupling constant via matrix model techniques, and finally we will compare our results with minimal surface computations in the bulk, finding perfect agreement.
72

Modelagem detalhada de sistemas nucleares avançados do tipo leito de bolas com combustível encapsulado

GARCÍA, Jesús Alberto Rosales 18 May 2015 (has links)
Submitted by Isaac Francisco de Souza Dias (isaac.souzadias@ufpe.br) on 2016-02-16T18:00:16Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_completa_portugues_Jesus - Final_B1.pdf: 4458139 bytes, checksum: 1ccef01f0261985c1f30824dd4c94ae6 (MD5) / Made available in DSpace on 2016-02-16T18:00:16Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_completa_portugues_Jesus - Final_B1.pdf: 4458139 bytes, checksum: 1ccef01f0261985c1f30824dd4c94ae6 (MD5) Previous issue date: 2015-05-18 / CAPES / A sustentabilidade da energia nuclear dependerá, entre outros fatores, da capacidade de redução dos inventários dos resíduos nucleares de vida longa. Com esse objetivo, desenvolveu-se a nova geração de reatores nucleares, com seis protótipos que se destacam por sua segurança, resistência à proliferação e a gestão dos resíduos. Dentro dessa nova geração de reatores, encontram-se os reatores de temperatura muito alta (VHTR), pela capacidade de produzir energia e a obtenção de altas temperaturas na saída do refrigerante, para seu uso em aplicações de alta temperatura como a produção de hidrogênio. Os ADS (Accelerator Driven Systems), que podem ser projetados como VHTR, são sistemas projetados para a redução dos elementos transurânicos provenientes dos LWRs (Light Water Reactors). O TADSEA (Transmutation Advanced Device for sustainable Energy Applications) é um ADS do tipo leito de bolas, projetado para atingir uma queima profunda dos elementos transurânicos, a produção colateral de energia e a obtenção de altas temperaturas para produzir hidrogênio. O presente trabalho têm como objetivo realizar melhoras no projeto conceitual do TADSEA, através da simulação geométrica detalhada do combustível, para o qual foi desenvolvida e avaliada uma metodologia para a modelagem computacional detalhada da dupla heterogeneidade do combustível em um leito de bolas, usando o código probabilista MCNPX. Foram incluídos novos elementos no projeto como a blindagem, as barras absorvedoras para garantir a segurança do sistema, e foi avaliado o desempenho na redução dos resíduos e sua radiotoxicidade associada, assim como a produção de energia. / The sustainability of nuclear energy will depend of the capability reduction of the inventories of long-lived nuclear waste. With this goal, it was developed the new generation of nuclear reactors with six prototypes, which stand out for their safety, proliferation resistance and the waste management. Within this new reactors generation, there is the very high temperature reactor (VHTR), designed to produce energy and to obtain high temperatures in the coolant, for their use in high temperature applications such as hydrogen production. The ADSs, which can be designed as VHTRs, are systems designed to reduce the mass of transuranic elements coming from the LWRs. The TADSEA is an ADS, pebble bed type, designed to achieve deep burning levels in the fuel, the power generation, and to obtain high temperatures to produce hydrogen. The aim of this study is to make the TADSEA conceptual re-design, by means of a detailed fuel geometric simulation, for which it was developed and evaluated a methodology for the detailed computational simulation of the fuel double heterogeneity in pebble-bed nuclear core, using the probabilistic code MCNPX. New design elements such as the shield and absorbers bars were included, and the performance in the reduction of nuclear waste and their associated radiotoxicity as well as the energy production were evaluated.
73

A publicidade na história: análise da ideologia veiculada na Revista Veja (1979-1985) / The advertising in history: analisys of ideology conveyed by de magazine Veja (1979-1985)

Milcheski, Alana 20 March 2015 (has links)
Made available in DSpace on 2017-07-10T17:55:36Z (GMT). No. of bitstreams: 1 Alana_Milcheski.pdf: 10147843 bytes, checksum: db4509b21c1eada526035e05a7d87acf (MD5) Previous issue date: 2015-03-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This scientific research analyzes the ideology conveyed by advertising between the years 1979 to 1985, through of print ads in the Veja Magazine. For this we try understand how does the production of an advertising piece, emphasizing aspects from the general functioning of advertising as a whole, for example, the role that advertising has on society, to more specific aspects uch as the use of the brand in its construction. We explained these aspects through the development of a theoretical interpretation, which includes the main discussions related to the theme, as the historicizing of advertising, the Culture Industry and the production of the cycle. The ads were understood as historical sources and from this perspective we try to construct an appropriate methodology both for the historical analysis as for ideological analysis, considering the relationship between them, because for the formation of ideology is intrinsic to the development of society / Esta pesquisa analisa a ideologia veiculada pela publicidade entre os anos de 1979 a 1985, através dos anúncios impressos na Revista Veja. Para isso buscamos compreender como ocorre a produção de uma peça publicitária, considerando aspectos que vão desde o funcionamento geral da publicidade como um todo, no sentido de qual é o papel que ela ocupa na organização da vida social, até aspectos mais específicos, como a utilização da marca em sua construção. Dessa forma problematizamos esses aspectos através do desenvolvimento de uma abordagem teórica que englobou as principais discussões relacionadas à temática, como a historicização da publicidade, a Indústria Cultural e o ciclo de produção da mercadoria. Os anúncios foram compreendidos como fontes históricas e através dessa perspectiva buscamos construir uma metodologia adequada tanto para a análise propriamente histórica, quanto para a análise ideológica, sendo que ambas se relacionam, pois a formação da ideologia é intrínseca ao desenvolvimento da sociedade
74

Analytic Conformal Bootstrap in 2D CFT / 2次元共形ブートストラップの解析的手法

Kusuki, Yuya 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第22996号 / 理博第4673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 高柳 匡, 教授 杉本 茂樹, 教授 田中 貴浩 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
75

Simulating ADS-B and CPDLC messages with SDR / Simulering av ADS-B- och CPDLC-meddelanden med hjälp av SDR

Gustafsson, Hanna, Eskilsson, Sofie January 2020 (has links)
Several studies have shown insufficient security in air traffic communication. The increase in air traffic in recent years also increases the need for improved security. CPDLC is used to communicate in text over the data link and ADS-B determines the position of an aircraft. These techniques are looked upon and simulated in the thesis. By proving that ADS-B and CPDLC messages can be transmitted and received with cheap and easy access equipment we want to show the simplicity in performing an attack. The thesis state a foundation to simulate attacks in the future so further work concerning the lack of security can be done.
76

Black hole formation, holographic thermalization and the AdS/CFT correspondence

Lindgren, Erik Jonathan 05 July 2017 (has links) (PDF)
The AdS/CFT correspondence is one of the most important discoveries in theoretical physics in recent years. It states that certain quantum mechanical theories can actually be described by classical gravity in one higher dimension, in a spacetime called anti-de Sitter (AdS) space. This means that to compute any measurable quantity in the quantum theory, we can instead do a computation in classical general relativity, and vice versa. What makes this duality so useful is that it relates theories with weak coupling to theories with strong coupling and thus provides a new tool for tackling strongly coupled quantum field theories, which are notoriously difficult to handle using conventional methods. Originally discovered in the context of string theory, this duality has now found a wide range of applications, from condensed matter physics to high temperature plasmas in quantum chromodynamics (QCD).During the course of my PhD I have mostly studied time dependent processes, in particular thermalization processes, in quantum field theories using the AdS/CFT correspondence. On the gravity side, this is dual to dynamical formation of black holes from the collapse of matter fields. By studying the gravitational collapse process in detail, we can then draw conclusions about the dynamical formation of a thermal state in the dual quantum field theory. Certain quantum field theories (such as QCD) enjoy a property called confinement, which in the case of QCD states that quarks can not be isolated. Using mostly numerical methods, I have studied how confinement affects thermalization in quantum field theories. We found that sometimes the system never thermalizes and field theory observables undergo interesting quasiperiodic behaviour. In another line of research, I have studied formation of black holes in three dimensions which due to the simplified nature of three-dimensional gravity can be done using analytical methods. This has led to the discovery of new solutions of three-dimensional gravity corresponding to the formation of black holes without spherical symmetry, which can provide a deeper understanding of thermalization in two-dimensional quantum field theories. In a third line of research, I have studied higher spin gravity in three dimensions, an exotic extension of three-dimensional gravity which includes fields with spin higher than two, and found a new method to construct black hole solutions carrying higher spin charge. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
77

Návrh univerzitního firewallu na platformě Cisco

Burian, Jan January 2017 (has links)
The diploma thesis focuses on design of university firewall on Cisco platform. The design deals with important functionalities, which are used in the current solution. These include routing, network address translation, access control lists, VPN. The thesis furher deals with dynamic insertion rules, which are generated based on traffic analysis by Flowmon probe and its ADS module. The new design is implemented in a testing environment and its funcionality is verified. The thesis will serve like feasibility study for final implementation in the production MENDELU network.
78

DPP: Dual Path PKI for Secure Aircraft Data Communication

Buchholz, Alexander Karl 02 May 2013 (has links)
Through application of modern technology, aviation systems are becoming more automated and are relying less on antiquated air traffic control (ATC) voice systems. Aircraft are now able to wirelessly broadcast and receive identity and location information using transponder technology. This helps reduce controller workload and allows the aircraft to take more responsibility for maintaining safe separation. However, these systems lack source authentication methods or the ability to check the integrity of message content. This opens the door for hackers to potentially create fraudulent messages or manipulate message content. This thesis presents a solution to handling many of the potential security issues in aircraft data communication. This is accomplished through the implementation of a Dual Path PKI (DPP) design which includes a novel approach to handling certificate revocation through session certificates. DPP defines two authentication protocols, one between aircraft and another between aircraft and ATC, to achieve source authentication. Digital signature technology is utilized to achieve message content and source integrity as well as enable bootstrapping DPP into current ATC systems. DPP employs cutting-edge elliptic curve cryptography (ECC) algorithms to increase performance and reduce overhead. T is found that the DPP design successfully mitigates several of the cyber security concerns in aircraft and ATC data communications. An implementation of the design shows that anticipated ATC systems can accommodate the additional processing power and bandwidth required by DPP to successfully achieve system integrity and security. / Master of Science
79

The study on quantum field theories from numerical approaches / 数値解析手法による場の量子論の研究

Kawai, Daisuke 26 March 2018 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20901号 / 理博第4353号 / 新制||理||1625(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 川合 光, 教授 青木 慎也, 准教授 菅沼 秀夫 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
80

ADS/CFT correspondence in a non-supersymmetric Yi-deformed background

Prinsloo, Andrea Helen 22 December 2008 (has links)
A non-supersymmetric Yi-deformed AdS/CFT correspondence has recently been conjectured by Frolov. A detailed description of both sides of this proposed gauge/string duality is presented. The analogy that exists between single trace gauge theory operators in the SU(3) sector and i-deformed SU(3) integrable spin chains is also discussed. Frolov, Roiban and Tseytlin’s leading order comparison between the ideformed spin chain coherent state action and i-deformed string worldsheet action in the semiclassical limit is reviewed. A particular Lax pair representation for the first order semiclassical i-deformed spin chain/string action is then constructed.

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