841 resultados para Energia eólica : Aspectos econômicos


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O presente trabalho analisa cinco inventários dos maiores produtores de café no município de Piraí, no Vale do Paraíba, entre os anos de 1839 e 1848, totalizando quase dois mil escravos. A partir de uma perspectiva de historia econômica pretende-se mostrar que a produção cafeeira permitia o acúmulo de capital e seu reinvestimento na expansão da monocultura. O estudo dos cativeiros também busca evidenciar que os cativos, africanos em sua maioria, eram agentes na formação de suas famílias, mantendo um espaço de sociabilidade baseado na memória e na construção de uma nova identidade afro-brasileira.

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This paper studies the incentives underlying the relations between foreign countries and rival domestic groups. It models the interaction in a infinitely-repeated game between these three players. The domestic groups bargain for a split of the domestic surplus and may engage in violent dispute for power and in unilateral mass killing processes. The foreign country may choose to support one of these groups in exchange for monetary transfers. The paper characterizes the parametric set in which strategies leading to no violent disputes nor mass killings are Subgame Perfect Nash Equilibra in the presence of foreign support, but not in its absence.

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Qual o efeito de eleições em ativos reais? É possível mensurar diretamente a diferença de preços mesmo que só possamos enxergar um dos resultados potenciais? Essa dissertação estima esses efeitos utilizando metodologia baseada em opções sobre ações. O modelo aqui desenvolvido adaptção tradicional Black-Scholes para incorporar dois novos parâmetros: um salto no preço do ativo perfeitamente antecipado e uma série de probabilidades diárias refletindo as crenças sobre quem venceria a corrida eleitoral. Aplicamos esse método para o caso brasileiro das Eleições Presidenciais de 2014 e a Petrobras - uma importante companhia do setor petrolífero do país -utilizando dados de bolsa do segundo turno das eleições. Os resultados encontrados mostram uma diferença de 65-77% para o valor da companhia, dependendo de quem vencesse nas urnas. Isso é equivalente a aproximadamente 2.5% do PIB de 2014 do país.

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O item não apresenta o texto completo, para aquisição do livro na íntegra você poderá acessar a Editora da UFSCar por meio do link: www.editora.ufscar.br

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Este projecto tem como principal objectivo a criação de sistemas autónomos de^alimentação para redes de sensores sem fios (RSSF) que prolonguem a autonomia das mesmas. Considerando que, geralmente, a alimentação das RSSF é fornecida por baterias e devido à limitação que estas impõem a nível de durabilidade e autonomia é crucial desenvolver sistemas capazes de captar e armazenar energia ambiental de modo a disponibilizá-la aos nós sensores quando estes necessitarem. Assim sendo, este projecto apresenta três protótipos cujo intuito visa prolongar a longevidade dos nós sensores. Nesta conformidade recorreu-se ao aproveitamento da energia produzida pelo sol, vento e cursos de água. Foram estudados dois protótipos solares, um com ligação directa ao elemento de armazenamento e o outro com um circuito que deve transferir o máximo de potência fornecida pela fonte. Para o aproveitamento do fluxo de ar foi desenvolvido um pequeno gerador trifásico com uma estrutura de captação de energia segundo o modelo de pás do aerogerador Savonius. As características (tensão e corrente) foram analisadas com o objectivo de poder desenvolver um circuito de controlo de carga para as baterias. O último sistema de controlo foi dirigido ao aproveitamento da água proveniente das levadas ou ribeiras. Este sistema também é composto por um pequeno gerador trifásico ao qual foi associado um sistema de pás do tipo Pelton. Este protótipo foi proposto para situações em o caudal à saída de um reservatório se mantém constante evitando desta forma, a necessidade de utilização de elementos de armazenamento de energia Todos os sistemas possuem circuitos que permitem a monitorização de variáveis fundamentais para a avaliação dos mesmos. Para a transferência de dados foi utilizada uma rede de sensores sem fios, com recurso a um rádio XBee. Estes dados são encaminhados para uma base de dados presente na estação central. Após todo o tratamento de dados, a informação é disponibilizada através de uma página da Internet.

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O trabalho tem por objetivo principal estudar a utilização de aerogeradores para microprodução de energia (menor que 1 W) de forma a poderem alimentar os nós das redes de sensores sem fios. Para tal, analisaram-se dois tipos de aerogeradores, os de eixo vertical e os de eixo horizontal, tendo-se efetuado simulações de CFD (Computational Fluid Dynamics) para verificar o desempenho das turbinas, de forma a determinar qual é o mais adequado. Foi realizado o projeto dos dois sistemas e analisou-se em particular as turbinas, os geradores e os conversores de potência de forma a avaliar o desempenho. Efetuaram-se simulações para determinar o comportamento esperado e posteriormente realizaram-se as medições experimentais num túnel de vento, tendo-se concluído que, para a dimensão dos aerogeradores desenvolvidos, o sistema vertical produz mais potência que o de eixo horizontal para velocidades de vento inferiores a 4,5 m/s e tem a grande vantagem de não ser significativamente afetado pela turbulência do vento. No entanto, o sistema de eixo horizontal é sempre mais eficiente para qualquer velocidade de vento, devido ao seu coeficiente de potência ser sempre superior ao do sistema vertical. Também se comparou o desempenho do conversor DC-DC redutor-elevador inversor com o elevador tendo-se determinado que o segundo apresenta melhor desempenho, na gama de valores de tensão utilizados no trabalho. Por fim implementaram-se os sistemas em ambiente real de forma a verificar como se comportam quando estão expostos aos elementos com a velocidade e a direção do vento a variar. Concluiu-se que mesmo com ventos fracos a potência produzida é suficiente para carregar uma bateria de 3,6 V (tensão nominal) e alimentar a carga, pelo que o uso de energia eólica é uma boa alternativa à energia fotovoltaica.

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CAMPOS,Maria da Luz Góis; ANEZ,Miguel Eduar- do Moreno; CARÍCIO,Marcelo Rique. Estratégias de Competitividade Industrial em Empresas Cooperativas:O caso COMTERN. In:ENCONTRO NACIONAL DE ENGENHARIA DE PRODUÇÃO, 23, 2003, Minas Gerais. Anais...Ouro Petro: ADEPRO, 2003. p. 1-8.

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The consumption of energy on the planet is currently based on fossil fuels. They are responsible for adverse effects on the environment. Renewables propose solutions for this scenario, but must face issues related to the capacity of the power supply. Wind energy offshore emerging as a promising alternative. The speed and stability are greater winds over oceans, but the variability of these may cause inconvenience to the generation of electric power fluctuations. To reduce this, a combination of wind farms geographically distributed was proposed. The greater the distance between them, the lower the correlation between the wind velocity, increasing the likelihood that together achieve more stable power system with less fluctuations in power generation. The efficient use of production capacity of the wind park however, depends on their distribution in marine environments. The objective of this research was to analyze the optimal allocation of wind farms offshore on the east coast of the U.S. by Modern Portfolio Theory. The Modern Portfolio Theory was used so that the process of building portfolios of wind energy offshore contemplate the particularity of intermittency of wind, through calculations of return and risk of the production of wind farms. The research was conducted with 25.934 observations of energy produced by wind farms 11 hypothetical offshore, from the installation of 01 simulated ocean turbine with a capacity of 5 MW. The data show hourly time resolution and covers the period between January 1, 1998 until December 31, 2002. Through the Matlab R software, six were calculated minimum variance portfolios, each for a period of time distinct. Given the inequality of the variability of wind over time, set up four strategies rebalancing to evaluate the performance of the related portfolios, which enabled us to identify the most beneficial to the stability of the wind energy production offshore. The results showed that the production of wind energy for 1998, 1999, 2000 and 2001 should be considered by the portfolio weights calculated for the same periods, respectively. Energy data for 2002 should use the weights derived from the portfolio calculated in the previous time period. Finally, the production of wind energy in the period 1998-2002 should also be weighted by 1/11. It follows therefore that the portfolios found failed to show reduced levels of variability when compared to the individual production of wind farms hypothetical offshore

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The research and development of wind turbine blades are essential to keep pace with worldwide growth in the renewable energy sector. Although currently blades are typically produced using glass fiber reinforced composite materials, the tendency for larger size blades, particularly for offshore applications, has increased the interest on carbon fiber reinforced composites because of the potential for increased stiffness and weight reduction. In this study a model of blade designed for large generators (5 MW) was studied on a small scale. A numerical simulation was performed to determine the aerodynamic loading using a Computational Fluid Dynamics (CFD) software. Two blades were then designed and manufactured using epoxy matrix composites: one reinforced with glass fibers and the other with carbon fibers. For the structural calculations, maximum stress failure criterion was adopted. The blades were manufactured by Vacuum Assisted Resin Transfer Molding (VARTM), typical for this type of component. A weight comparison of the two blades was performed and the weight of the carbon fiber blade was approximately 45% of the weight of the fiberglass reinforced blade. Static bending tests were carried out on the blades for various percentages of the design load and deflections measurements were compared with the values obtained from finite element simulations. A good agreement was observed between the measured and calculated deflections. In summary, the results of this study confirm that the low density combined with high mechanical properties of carbon fibers are particularly attractive for the production of large size wind turbine blades

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A proposal for a global analysis of sustainability in projects related in oil facilities is presented. By considering economic, environmental and social aspects in the early stages of design, the suggested method is more comprehensive and can be used to complement the analysis commonly applied in the petroleum industry, such as: Study of Technical and Economic Feasibility; Environmental Impact Assessment and Risk Analysis. Several authors, associations, certification bodies and oil companies suggest different approaches to study sustainability in some specific activities (or industries). In this study, a checklist of significant sustainability aspects for the oil industry (surface facilities) was assembled. In addition, a matrix was developed to assess the sustainability items relevant to these projects. In this work, the checklist interacts with the matrix to perform a "Preliminary Analysis of Sustainability of the Enterprise" (APSE). This method allows the identification of aspects that contribute significantly to global sustainability. From this analysis, which includes economic, social and environmental aspects, is built a report that is used to analyze qualitatively and quantitatively the impact of the sustainability aspects of the project. In this analysis are identified items that strongly influence the economic, social or environmental aspects and evaluated alternatives that can increase the overall sustainability of the project. Finally, the alternatives that can be used to indicate the most sustainable option are identified. This method was applied in a project (design) of a small offshore platform. This case study shows how the APSE can contribute to the identification of sustainability initiatives for the enterprise. The results showed that relevant aspects can contribute decisively to global sustainability. Finally, it was observed that the proposed method can contribute to increased rates of sustainability, even after application of analysis commonly used in these projects

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The debate around the thematic of Corporate Social Responsibility - CSR involves economic, social, cultural and symbolic aspects in the relations established between company and society. In Brazilian reality, the CSR, understood as enterprise actions, external and/or internal, that contributes to social and ambient improvement, gains greater visibility in 1990 decade. Although the significant increase of theoretical productions about CSR pertinent elements, it is still scarce the studies that treats about the relation company/society in the northeastern reality, and singularly, in Rio Grande do Norte. It was in this perspective, that, in being the salt industry one of most important in the potiguar economic history formation , the present work investigated practicies and perceptions of salt entrepreneurship about CSR. Considering all the Rio Grande do Norte salt industry history phases, since the period of the Brazil s settling, as well as the characteristics of the study object, was opted to the qualitative research, objectified in interviews half-structuralized realized with the salt segment entrepreneurs, as well as professionals of ambient management and human resources working in potiguar salt segment. The research main results indicated a coexistence between the mechanisms of management seated on personal and paternalists relations, typical of traditional salt industry, and the emergency of innovative elements typical of the modern management, like the CSR. In this context, a tension between continuity and rupture with the traditional mechanisms of management in salt entrepreneurship actions

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This study attempts to investigate the school administration in the Department of Education of Rio Grande de Norte, in the period 1924 to 1928, in the context of conservative modernization in its management, implemented by Nestor Lima dos Santos. Addresses the trends of administrative Nestor Santos Lima and sequence of these variables so that we can correlate and monitor the development of various economic, social, cultural and political, to show how influenced and even determined the direction of education, not only the state of RN, but throughout the country. For this purpose, it is the recapitulation of the history of life, experiences of work and travel reports of this important figure, including administrative concepts, aiming to identify the school administration, introduced by him in the 1920s, as those who received influence of characters that included the social and historical context of the time, reconstituting the ways following the education. It was developed by Nestor shares in Lima on the administration of public schools, their way of management, and can see how was the process of modernization of education in Rio Grande do Norte state and how it followed the rapid changes, experienced by Brazil, during this period. Show up on the design aspects of modernizing Nestor Lima in the Department of Education, the Director General of Administrative Acts, the internal record of school groups, Isolated Schools, Schools rudimentary and the newly created Board of Education, highlighting the Internal Rules of Council but the General Regulations of the Department of Education. This work also highlights the proposed administrative Nestor of Lima, while educational model of an operating system of the organization, training and education, which is present in the area of production of discourse, through body practice, characteristic of the record established levels of policy development and implementation of educational instruction in all state. Key-words: school administration. Conservative modernization. Public Education

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)