Este trabalho consistiu no desenvolvimento e análise comparativa de rotas de cominuição para Itabiritos Compactos do Quadrilátero Ferrífero a partir de uma amostra de grande volume. As rotas desenvolvidas foram: Rota Convencional, composta por quatro estágios de britagem até a malha de 12 mm, seguido por moagem em moinho de bolas. Rota SAB, composta por uma etapa de britagem até a malha de 200 mm, seguida por moagem SAG e moagem em moinho de bolas. Para esta rota foi estudada a inclusão de uma segunda etapa de britagem, antes da alimentação do moinho SAG, e de uma britagem de pebbles, para a carga circulante do moinho SAG. Rota SSSAG, composta por uma etapa de britagem seguida por moagem SAG. Assim como para a rota SAB, foi avaliada para esta última rota a inclusão de uma segunda etapa de britagem, antes da alimentação do moinho SAG. Em todas as rotas, o produto da moagem foi fixado em 10% retido em 0,15 mm Os circuitos de moagem, SAG e de moinho de bolas foram desenvolvidos a partir de resultados de ensaios em escala piloto, ajustados via simulador JKSimMet. O consumo de energia e o dimensionamento dos equipamentos obtidos a partir dos ensaios piloto foram comparados aos resultados obtidos pelos métodos Bond e de Donda. O circuito de britagem foi dimensionado a partir de um ensaio industrial, que determinou a eficiência de britagem em função da abertura na posição fechada do britador. As rotas desenvolvidas foram comparadas quanto ao consumo específico de energia (kWh/t), dimensionamento dos equipamentos e geração de material menor que 0,010 mm (lamas) no produto da moagem. A rota SSSAG apresentou o menor consumo de energia e também o menor quantitativo de equipamentos. Quanto à geração de lama no produto da moagem, foram obtidos valores semelhantes nos ensaios piloto das três rotas estudadas. / This work consists in the development and comparative analysis of comminution routes to Compact Itabirites from Quadrilátero Ferrífero, based on a large volume sample. The developed routes were: Conventional Route, comprising four crushing stages, down to 12 mm, followed by ball milling. SAB Route comprising one crushing step, down to 200 mm, followed by SAG milling and ball milling. Secondary crushing and pebble crushing were also included as variations of SAB route. Route SSSAG, comprising one crushing step, down to 200 mm, followed by SAG milling. Secondary crushing was also included as a variation of SSSAG route. In all cases grinding product was set to 10% retained at 0,15 mm. All grinding models were fitted at JKSimMet simulator on the basis of pilot plant data. Energy consumption and equipment design were compared with Bond and Donda method results. Crushing circuit design was based on industrial tests carried out for determining efficiency as a function of closed side setting (CSS). The routes were compared in term of energy consumption (kWh/t), comminution equipment numbers and the amount passing at 0,010 mm (slimes) in the grinding circuit product. The SSSAG route indicated the lowest energy consumption, together less pieces of equipment. Similar slime values were obtained for all three routes in pilot testing.

O objetivo desse trabalho é o estudo dos operadores p-compactos e da propriedade de p-aproximação. Estes conceitos estão relacionados a importantes resultados de A. Gröthendieck sobre compacidade e a propriedade de aproximação que foram generalizados em [21] e estudados em [3], [6] e [7]. / The purpose of this work is the study of p-compact operators and the p-approximation property. These concepts are connected with important results by A. Gröthendieck about compactness and approximation property that were generalized in [21] and studied in [3], [6] and [7].

"We focus attention on single-punch compaction of metal powders in cylindrical dies. In one case, we consider solid cylindrical compacts, and take the die walls to be frictionless in order to isolate the effects of initial nonuniformities in powder fill on the final green density distribution of the compact. First, a model is introduced in which the die is filled with n distinct powders that occupy concentric annular regions within the die. The model requires that the balance of mass, the balance of momentum, and a realistic equation of state be satisfied in each region, and includes a plausible constitutive relation that relates the induced radial pressure in each powder region to the corresponding axial pressure and the relative movements of the interfaces that confine the region. For specified powder properties, the model predicts the movements of the interface between the powders, the final density in each region, the pressure maintained in each region, and the total compaction load required. In the special case of two powders (n=2), we predict how the radial movement of the single interface depends on the mismatch between the properties of the two powders. For large values of n, and for powder properties that change gradually from one powder to the next, the model approximates a single powder filled nonuniformly in the die. Finally, a model is developed for a single powder with continuously varying powder properties. Formally, the model may be obtained by taking the limit of the n-powder model as n becomes unbounded. Employing the continuous model, we determine how nonuniformities in initial fill density can be offset by nonuniformities in other powder properties to yield perfectly uniform green densities. In a second case, we consider axisymmetric, hollow, cylindrical compacts, and include the effects of friction at the die wall and the core rod. The ratio of the induced radial pressure to the applied axial pressure is assumed to be constant throughout the compaction, and Coulomb friction acts between the powder and the die wall as well as between the powder and the core rod. We derive a closed form solution for the axial and radial variation of the axial pressure, radial pressure, and shear stress throughout the compact. This solution is combined with a plausible equation of state to predict the final green density distribution and the variation of applied load throughout the compact."

O objetivo deste trabalho é realizar uma análise paramétrica do processo de desumidificação de ar comprimido em trocadores de calor compactos com superfícies intensificadoras do tipo aletas deslocadas. A umidade contida no ar comprimido precisa ser retirada do sistema para evitar a formação de condensado nas linhas de distribuição, nos atuadores ou nos dispositivos finais. Utiliza-se o processo de desumidificação por resfriamento onde a temperatura do ar é diminuída até alcançar o ponto de orvalho, resultando em formação de condensado. O desumidificador é constituído por dois trocadores de calor (recuperador e evaporador), sendo cada um deles dividido em duas regiões. Realizou-se a modelagem do processo de transferência de calor para cada um dos trocadores. Utilizou-se o método do potencial de entalpias para determinar os coeficientes globais de transferência de calor de cada trocador. Para a realização da simulação numérica, foi implementado um programa utilizando como ferramenta computacional o programa “Engineering Equation Solver" (EES). O estudo foi feito variando-se os parâmetros geométricos do trocador de calor e verificando sua influência nos coeficientes de transferência de calor, nos calores trocados e nas condições de saída do ar. Primeiramente, cada parâmetro foi analisado individualmente e depois com algumas combinações. Concluiu-se que as dimensões das aletas no recuperador e os comprimentos do recuperador e do evaporador são os parâmetros que mais influenciam nas propriedades do ar comprimido na saída do desumidificador. / The objective of this work is to conduct a parametric analysis of the dehumidification process of compressed air in compact heat exchangers with Offset Strip Fins. The humidity carried by the compressed air should be removed from the system to prevent the condensation in the distribution lines and in the actuators or the final devices. The dehumidification process by cooling occurs when the temperature of the air is diminished until reaching the dew point, resulting in condensation of water vapor. The dehumidifier is constituted by two heat exchangers (recuperator and evaporator), each one of them being divided in two regions. A modeling of the heat and mass transfer process for each heat exchangers, was performed. The enthalpy driving potential method was used to determine the overall heat transfer coefficients of each heat exchanger. The numerical simulation was implemented by using the computational software "Engineering Equation Solver"(EES). The study was made varying the geometric parameters of the heat exchanger and verifying its influences on the heat transfer coefficients, the heat transfer and pressure drop, and the air exit conditions. First, each parameter was analyzed individually and then with some combinations. Its was concluded that the fins dimensions in both regions of the lengths of the recuperator and the evaporator are the parameters that have larger influence on the exit compressed air properties.

This study explores the relationship between planning policy and quality of life and, in doing so, contributes to long running debates occurring within the planning literature, and between planning practitioners and planning theorists, about the nature of this relationship. Specifically, the study investigates the relationship between planning policy's approach to combining residential and non-residential uses, an understudied area of policy, and the quality of life of tenants' and residents' association (TARA) members, an understudied population which frequently participates in the planning system. Within the study, quality of life is understood in terms of preference-satisfaction theory which equates the 'good' life with the satisfaction of preferences. Subsequently, where policy's aspirations for the built environment overlap with the environmental preferences of TARA members, it is assumed that policy might, when reflected in the built environment, support members' quality of life. To investigate such instances of overlap, the study first explored policy's approach to combining residential and non-residential uses through a qualitative content analysis of written policy, interviews with local authority planning officers and an analysis of planning applications and their associated decision notices. Then, to investigate the environmental preferences of TARA members, focus groups were held with a diverse sample of TARAs. These focus groups suggested ways of amending policy so that it might better satisfy members' preferences and, perhaps then, better support their quality of life. A conceptual framework was developed to begin to explore the deliverability of these amendments with data for this exercise collected from self-proclaimed representative bodies for the planning profession and housebuilding industry. In pursuing these interests, insights into a number of additional issues emerged, including, the relationship between policy as 'content' and policy as 'process', the interests, activities and spatial distribution of TARAs, the planning system's potential to support the quality of life of TARA members, and planners' and housebuilders' attitudes towards land use mix and the State's planning apparatus. Taken in its totality though, the study‘s major contribution perhaps lies in suggesting answers to the vexed question of what should be civil society's role in the planning system. In terms of land use mix, the study found that planning policy and TARA members shared a largely similar conceptualisation of the 'good' residential environment with both favouring predominantly residential areas, featuring pockets of green space, 'everyday' services, and the exclusion of most traffic generating, obtrusive and noisy uses. They also shared a similar conceptualisation of the 'good' town or city centre with both favouring land use mix, a concentration of activities and the presence of residential occupiers. Consequently, in these instances, policy perhaps seems suited to supporting the quality of life of TARA members. However, in other instances, members' preferences and policy‘s requirements were seen to diverge. Furthermore, the task of revising policy to avoid these points of divergence seems challenging. The study updates and expands knowledge on an understudied area of policy and a relatively understudied population. It presents insights into policy's approach to land use mix, and attitudes towards this approach, at a time when the planning system is experiencing considerable change with regional planning due to be abolished, neighbourhood planning introduced and a new form of national planning policy launched. The study comments on the implications for the research findings of these various developments. It also identifies environmental designs and characteristics that might be of interest to policy-makers if an objective is to address the concerns of a frequently vocal participant in the planning system (i.e. TARAs).

While the spectral theory of compact operators is known to many, knowledge regarding the relationship between eigenvalues and approximation numbers might be less known. By examining these numbers in tandem, one may develop a link between eigenvalues and l^p spaces. In this paper, we develop the background of this connection with in-depth examples.

A melhoria nos aspectos de eficiência e de segurança dos reatores nucleares compactos está diretamente ligada às inovações nos combustíveis e na geometria dos Elementos Combustíveis - ou E.C. - como é o caso do tipo Placa, em comparação com o do tipo Vareta. Do ponto de vista mecânico, garantir que a estrutura de um E.C. está segura para funcionar em um reator PWR compacto é afirmar que esta cumpre os requisitos funcionais de projeto para estruturas deste tipo e aplicação, presentes na norma ANSI/ANS-57.5-1996; e também que as tensões resultantes dos carregamentos impostos sobre si são menores do que os limites mecânicos admissíveis para os seus materiais estruturais, de acordo com a norma ASME III, divisão 1, subseção NB. Para desenvolver uma metodologia de análise mecânica buscando verificar o atendimento aos critérios das normas citadas, foi proposto um modelo conceitual computacional de E.C. placa e, posteriormente, este modelo foi submetido a uma série de análises computacionais que simularam a aplicação das combinações dos principais carregamentos atuantes. Os resultados extraídos das análises revelaram que os valores das tensões resultantes da aplicação dos carregamentos foram inferiores aos valores dos limites admissíveis dos materiais que compõem os seus componentes. Foi observado, também, que os deslocamentos resultantes não ultrapassaram os limites funcionais, que são o contato entre estruturas semelhantes vizinhas e/ou o contato da região superior desta estrutura com as estruturas de suporte do vaso de pressão que o contém. / The improvement in the efficiency and safety aspects of compact nuclear reactors is directly linked to innovations in fuels and the geometry of Fuel Elements - F.E. - as is the case of the Plate type, as compared to the Rod type. From a mechanical point of view, to ensure that the structure of an F.E. is safe to operate in a compact PWR reactor is necessary to state that it meets the functional design requirements for structures of this type and application, present in ANSI / ANS-57.5-1996; and also that the stresses resulting from the loads imposed on them are less than the permissible mechanical limits for their structural materials in accordance with ASME III, division 1, subsection NB. In order to develop a methodology of mechanical analysis to verify compliance with the criteria of the cited standards, a computational conceptual model of F.E. Plate structure was proposed and later this model was submitted to a series of computational analyzes that simulated the application of the combinations of the main active loads. The results obtained from the analyzes revealed that the values of the stresses resulting from the application of the loads were lower than the values of the allowable limits of the materials that make up their components. It was also observed that the resulting displacements did not exceed the functional limits, which are the contact between neighboring similar structures i.e. the contact of the upper region of this structure with the supporting structures of the pressure vessel containing it.

Solar power tower technology can achieve higher temperatures than the most common commercial technology using parabolic troughs. In order to take advantage of higher temperatures, new power cycles are needed for generating power at higher efficiencies. Supercritical carbon dioxide (S-CO2) power cycle is one of the alternatives that have been proposed for the future concentrated solar power (CSP) plants due to its high efficiency. On the other hand, carbon dioxide can also be a replacement for current heat transfer fluids (HTFs), i.e. oil, molten salt, and steam. The main disadvantages of the current HTFs are maximum operating temperature limit, required freeze protection units, and complex control systems. However, the main challenge about utilizing s-CO2 as the HTF is to design a receiver that can operate at high operating pressure (about 20 MPa) while maintaining excellent thermal performance. The existing tubular and windowed receivers are not suitable for this application; therefore, an innovative design is required to provide appropriate performance as well as mechanical strength. This research investigates the application of s-CO2 in solar power tower plants. First, a computationally efficient method is developed for designing the heliostat field in a solar power tower plant. Then, an innovative numerical approach is introduced to distribute the heat flux uniformly on the receiver surface. Next, different power cycles utilizing s-CO2 as the working fluid are analyzed. It is shown that including an appropriate bottoming cycle can further increase the power cycle efficiency. In the next step, a thermal receiver is designed based on compact heat exchanger (CHE) technology utilizing s-CO2 as the HTF. Finally, a 3MWth cavity receiver is designed using the CHE receivers as individual panels receiving solar flux from the heliostat field. Convective and radiative heat transfer models are employed to calculate bulk fluid and surface temperatures. The receiver efficiency is obtained as 80%, which can be further improved by optimizing the geometry of the cavity.

L'explosion des moyens de communication sans fil durant les quinze dernières années, ainsi que les services nécessitant des communications à haut débit ont conduit l'industrie du semiconducteur à s'intéresser de plus en plus au circuit intégré pour des applications analogiques radio-fréquences. Les dispositifs réalisés en technologie CMOS présentent aujourd'hui des performances les rendant intéressants pour la conception de circuits RF. Or, la plupart des modèles disponibles actuellement ne sont pas adaptés aux besoins des applications RF, et ne peuvent donc pas être utilisés tels quels pour la conception de tels circuits. Afin d'améliorer la connaissance et la modélisation du MOSFET pour ce type d'applications, nous avons développé, au cours de ces travaux de thèse, de nouvelles méthodes d'analyse de la partie extrinsèque du transistor MOS, basées sur la mesure de paramètres S, et sur une connaissance approfondie de la théorie du MOSFET et de sa technologie. Ces méthodes consistent à isoler les éléments extrinsèques pour les étudier et connaître leurs effets. Elles permettent une extraction et une modélisation rigoureuses de composantes telles que la résistance de grille ou le réseau substrat, dont l'influence au premier ordre sur le comportement RF du transistor a été mise en évidence. Elles ont également conduit à montrer l'existence d'effets haute fréquence de second ordre induits par ces éléments parasites du dispositif, et montrent l'évolution grandissante de leur impact, au fil des générations technologiques, sur les performances RF du composant.

<p>This paper examines corporate responses to the voluntary UN initiative; the Global Compact and the legally binding UN Norms initiative that are attempts, at the urging of the international community, at different types of regulation of corporate activity in international socio-economic settings. This examination is done within the framework of the Modern World-Systems theory and both questions of the paper are therefore grounded in the MWS theory`s possibility to predict and explain the corporations` response to the two initiatives. The two hypotheses used in this paper are corresponding to the questions and they state that the MWS theory can answer the two questions. The paper therefore employs an overreaching congruence method that uses the MWS theory to predict and explain the outcome of the case study and a complementary descriptive argumentation analysis. This is conducted in order to attain the data needed and to elucidate what the differences and similarities are between the two initiatives and what aspect can be attributed most explanatory value to understand the possible differences in attitude by the corporations. The outcome of the case study shows that corporations are more in favor of the Global Compact then they are concerning the UN norms which they opposes vehemently. This difference in reaction is attributed to the latter’s legally binding principle and this is in accord with the logic of the MWS theory which is granted high predictable and explanatory value concerning the corporations` response to the Global Compact and the UN norms.</p>