Made available in DSpace on 2014-10-09T12:33:34Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:34Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:33:34Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:34Z (GMT). No. of bitstreams: 0 / O IPEN-CNEN/SP produz o combustível para suprir o seu reator nuclear de pesquisas IEA-R1. O combustível é montado a partir de placas combustíveis contendo um núcleo do compósito U3Si2-Al. Uma boa homogeneidade na distribuição de urânio no núcleo da placa combustível é essencial, pois garante um bom desempenho sob irradiação. Considerando a baixa potência do reator IEA-R1, atualmente, a distribuição de urânio na placa combustível é avaliada apenas por meio de inspeção visual de radiografias. Contudo, tendo em vista a possibilidade do IPEN fabricar o combustível para o novo Reator Multipropósito Brasileiro (RMB), que terá potência elevada, tornou-se inadiável o desenvolvimento de uma metodologia para determinar quantitativamente a homogeneidade da distribuição de urânio no combustível. Este trabalho apresenta uma metodologia baseada na atenuação de raios X para quantificar a distribuição da concentração de urânio no núcleo da placa combustível, por meio da análise da densidade óptica de radiografias e comparação com padrões. Os resultados demonstraram a não aplicabilidade do método, considerando a especificação atual para as placas combustíveis, devido ao alto valor do erro intrínseco ao método. Contudo, o estudo dos erros envolvidos na metodologia, buscando aumentar a sua exatidão e precisão, pode viabilizar a aplicação do método para qualificar o produto final. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Access to nuclear technology and growing concern over the spread of nuclear weapons triggered an international debate in the 1960s that led to the creation of the Nonproliferation Treaty. Ratified in 1970, NPT was designed to prevent the horizontal spread of nuclear weapons and limit destructive uses of nuclear energy. At the same time, it also normalized the arsenals of existing nuclear states and encouraged exchanges of nuclear information, technology, and materials for peaceful purposes. Nonproliferation policy relies on a theory of the development process that identifies a nuclear frontier to locate evidence of nuclear capabilities. Absent from the proliferation model, however, are cases of covert nuclear weapons programs. For almost 50 years, it has been generally accepted that Israel is a nuclear weapon state, yet Israeli officials have never confirmed nor denied the possession of nuclear weapons. Israel has not signed NPT and has not appeared to conduct a nuclear test, in effect absolving the nuclear program's main reactor from international inspections. Uncertainty surrounding the Israeli program stems from a tradition of deliberate secrecy and deception that constitutes a national policy of opacity. This study argues that opacity has armed Israel with the privilege of nuclear immunity, exempting its secret nuclear activity from the standards and regulations imposed on all other nuclear weapon states. To circumvent the barriers built by opacity, a mixture of declassified material, nuclear history and security literature, and postcolonial studies refines the history of Israel's nuclear program. By examining the American-Israeli nuclear relationship, the sources of opacity, and the framework of nonproliferation that sustains an international nuclear regime, Israel's role in the nuclear world becomes visible.

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To date more than 1500 exoplanets have been discovered. A large number of these are hot Jupiters, Jupiter-sized planets orbiting < 0.1 au from their parent stars, due to limitations in observational techniques making them easier to detect than smaller planets in wider orbits. This is also, for the same reasons, the class of exoplanets with the most observational constraints. Due to the very large interaction between these planets and their parent stars they are believed to be tidally locked, causing a large temperature contrast between the permanently hot day side and colder night side. There are still many open questions about these planets. Many are observed to have inflated radii, i.e. the observed radius is larger for a given mass than evolutionary models predict. A mechanism that can transport some of the stellar heating into the interior of the planet may be able to explain this. The presence of hazes or clouds has been inferred on some planets, but their composition and distribution remain unknown. According to chemical equilibrium models TiO and VO should be present on the day side of the hottest of these planets, but these molecules have not yet been detected. Cold traps, where these molecules condense out on the night side, have been suggested to explain this. The efficiency of the heat redistribution from the day side to the night side has been found to vary significantly between different planets; the mechanism behind this is still unknown. To begin to answer many of these questions we need models capturing the three-dimensional nature of the atmospheres of these planets. General circulation models (GCMs) do this by solving the equations of fluid dynamics for the atmosphere coupled to a radiative transfer scheme. GCMs have previously been applied to several exoplanets, but many solve simplified fluid equations (shallow water or primitive equations) or highly parametrised radiation schemes (temperature-forcing, gray or band-averaged opacities). We here present an adaptation of the Met Office Unified Model (UM), a GCM used for weather predictions and climate studies for the Earth, to hot Jupiters. The UM solves the full 3D Euler equations for the fluid, and the radiation scheme uses the two-stream approximation and correlated-k method, which are state of the art for both Earth and exoplanet GCMs. This makes it ideally suited for the study of hot Jupiters. An important part of this work is devoted to the adaptation of the radiation scheme of the UM to hot Jupiters. This includes calculation of opacities for the main absorbers in these atmospheres from state-of-the-art high temperature line lists, the calculation of k-coefficients from these opacities, and making sure all aspects of the scheme perform satisfactorily at high temperatures and pressures. We have tested approximations made in previous works such as the two-stream approximation, use of band-averaged opacities and different treatments of gaseous overlap. Uncertainties in current models, such as the lack of high temperature line broadening parameters for these atmospheres, are discussed. We couple the adapted radiation scheme to the UM dynamical core, which has been tested independently. Our first application is devoted to one of the most well-observed hot Jupiters, HD 209458b. Differences between previous modelling works and our model are discussed, and we compare results from the full coupled model with results obtained using a temperature-forcing scheme. We have also developed a tool to calculate synthetic phase curves, and emission and transmission spectra from the output of our 3D model. This enables us to directly compare our model results to observations and test the effect of various parameters and model choices on observable quantities.

Black Western Thought: Toward a Theory of the Black Citizen-Object troubles and challenges the philosophical category of the human, particularly the black human. Oppositionally reading Enlightenment texts like Edmund Burke’s A Philosophical Enquiry into the Origins of our Ideas of the Sublime and Beautiful and Emanuel Kant’s Observations on the Feelings of the Beautiful and Sublime, I extend Emanuel Eze and Charles Mills critiques of Kant and the Enlightenment through relinquishing the quest for a black humanity. This project embraces the abjection of blackness and posits that in the rejection of quest for humanity the black citizen-object reveals heretofore unexplored ontology, epistemology, poetics, and philosophy. Through careful close-reading of poets Phillis Wheatley, Terrance Hayes, Natasha Trethewey, and Jericho Brown, this project explores the political and aesthetic possibility of extending the democracy of subjectivity and presiding intelligence to black aesthetic and intellectual productions. Moving away from the notion of blackness as fear-inducing, funky, reprobate, and disorderly, this project constantly seeks to play with the dark rather than play in the dark. This act of ‘playing with the dark’ manifests as an interrogation of Ralph Ellison’s Invisible Man in relationship to quantum physics and visibility / invisibility of blackness. The project hopes to shake the very stable ground of the ontology of aesthetics and academic discourse. / text

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2005. / Dr. Waymond R. Scott, Committee Member ; Dr. Aaron Lanterman, Committee Member ; Dr. Paul G. Steffes, Committee Chair ; Dr. Andrew F. Peterson, Committee Member ; Dr. Judith A. Curry, Committee Member. Vita. Includes bibliographical references.

xi, 578 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Rational deterrence theory posits that deterrence is more likely to be successful when a state credibly communicates to its adversary that it has both the capability and intent to retaliate against threats. Yet, second-generation nuclear states, which often exist in severe security environments, have largely adopted postures of nuclear ambiguity where they do not acknowledge their nuclear weapons capabilities or the circumstances under which they would use them. To date, research has been insufficiently comparative. While some existing research offers explanations for the ambiguous nuclear postures of individual countries, it does not permit us to draw inferences across cases and assess relative explanatory power. Through comparison, both within and across cases, this project develops a more general explanation of why nuclear states choose ambiguity over a visible deterrence posture. To this end, this project analyzes the nuclear postures of three countries: Israel, India, and Pakistan. Using process tracing and the congruence procedure methodology, I assess the relative validity of existing explanations for each case and then compare these findings across the three cases. This research suggests that regional security environments, characterized by disparities in power, create strong incentives for states to acquire nuclear weapons capabilities for deterrence as well as to retain an ambiguous posture. In particular, an ambiguous posture enables regional states to avoid the costs and dangers of competitive nuclear development vis-à-vis their adversaries. The three cases also suggest that patron state pressures for non-proliferation, which combine threats and incentives, are another important constraint on the nuclear posture of second-generation nuclear states. Other variables--such as the international non-proliferation regime, domestic political interests, and the personal moral reservations of some state leaders--play some role to varying degrees in individual cases. However, these effects are limited both within the broad history of individual cases as well as in cross-case comparison of the three states. Understanding these constraints is helpful for evaluating the efficacy of policy tools designed to prevent the spread of nuclear weapons as well as how to manage crises and conflicts between regional nuclear-armed states. / Committee in charge: Lars Skalnes, Chairperson, Political Science; Jane Kellett Cramer, Member, Political Science; Ronald Mitchell, Member, Political Science; Shaul Cohen, Outside Member, Geography

Made available in DSpace on 2014-06-11T19:23:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-07-24Bitstream added on 2014-06-13T20:30:08Z : No. of bitstreams: 1 barbosa_alpbf_me_jabo.pdf: 711874 bytes, checksum: 2ed60bdad987609854ea431a1857f8b2 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Considerando-se o petróleo um recurso natural não-renovável, o Biodiesel apresenta-se como relevante alternativa de combustível, sendo ele renovável, biodegradável e podendo ser produzido a partir de gordura animal ou óleo vegetal transesterificado com álcool anidro, na presença de catalisador. O presente trabalho teve como objetivo avaliar o desempenho operacional e a opacidade da fumaça de um trator agrícola funcionando com Biodiesel de mamona, em operação de preparo de solo. O ensaio foi conduzido no Departamento de Engenharia Rural da UNESP-Jaboticabal, em delineamento inteiramente casualizado, em esquema fatorial 6x2, com quatro repetições. O primeiro fator representa seis proporções percentuais de Biodiesel + diesel de B0 (0+100), B5 (5+95), B15 (15+85), B25 (25+75), B50 (50+50) e B75 (75+25) e o segundo representa duas operações de preparo do solo (gradagem e escarificação). Ressalta-se que B75 foi a máxima proporção de mistura, devido ao alto índice de viscosidade do biocombustível, sendo tal característica limitadora para o funcionamento do motor diesel. Os resultados evidenciaram aumento no consumo específico de 19% quando se utilizou B75 em relação a B0. A operação de gradagem teve consumo específico 16% maior em relação à operação de escarificação. Para a opacidade da fumaça, houve redução de 35% de B75 comparado com B0. / Considering petroleum as a non-renewable natural resource, Biodiesel presents itself as a relevant fuel alternative, being renewable, biodegradable and can be produced from vegetal oil transesterification with anhydride alcohol in the presence of a catalisator. This work has the goal of analyzing the operational performance and smoke opacity of a agricultural tractor running with mamona Biodiesel in soil tillage operations. The test was done in the Department of Rural Engineering of UNESP-Jaboticabal in design completely randomized, in factorial scheme 6x2, with four repetitions. The first factor represents six percentual proportions of Biodiesel plus diesel B0 (0+100), B5 (5+95), B15 (15+85), B25 (25+75), B50 (50+50) e B75 (75+25) and the second represents two soil tillage operations (harrowing and chiseling). It is important to note that B75 was the maximum mixture proportion due to the high level of biofuel viscosity, this characteristic being not recommended for diesel engines. The results showed that the specific consumption raised by 19% when B75 was used instead of B0. The harrowing operation had specific consumption 16% higher than the chiseling operation. For smoke opacity, it was noted a reduction of 35% of B75 compared to B0.