911 resultados para ENERGY-SYSTEMS


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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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The Bahamas is at great risk and vulnerability given its geographical features as a low-lying, sea encircled country. If projected sea level rise is reached by 2050, between 10-12% of territory will be lost, especially in coastal zones where the main tourism assets are located. Vulnerability could also be manifested if flight carbon emission taxes are established in the main source markets, representing an economic threat to the tourism sector for the islands. The impact of climate change on main tourism demand variables will cause some losses to the country‟s income and government revenues. This would be acting conjointly with some local threats to tourism assets and trends in future global tourism demand. The second and no less important threat is tropical cyclones, which may be associated with raising sea level. Estimations posited the amount of losses in excess of 2400 million US$ for the four decades under examination. It is to be pointed out that there is still a lack of comparatively accurate data collection and analysis on this subject, a point deserving more attention in order to deepen the understanding of, and to extract better lessons from these extreme events. In the same period, total estimated impacts of progressive climate change are between 17 and 19 billions of B$ with estimated discount rates applied. The Bahamas is a Small Island Developing State with low growth on GHG emissions (second in Latin America), as well as a relative short capacity to lower emissions in the future. The country has a relative delay in the application of renewable energy systems, a solution that, provided documented studies on-site, might turn out to be fundamental in the country‟s efforts to establish mitigation related policies. The Bahamas currently has institutions and organizations that deal with climate change-related issues and an important number of measures and courses of action have been set up by the government. Nevertheless, more coordination among them is needed and should include international institutions. This coordination is essential even for the first steps, i.e. to conduct studies with a bottom-up approach in order to draw more accurate programs on adaptation and mitigation. It is fundamental for tourism to keep track of potential losses in tourist attractions (and to act accordingly), related to correspondent losses in biodiversity, water resources and coastal erosion. Also, actions to fight climate change impacts might improve the islands security standards, quality of living and protect cultural and heritage assets. These elements may definitely shape the future of the country‟s competitiveness as a tourism destination. It is possible and necessary to decide about the options with good cost-benefit ratio and reasonable payback periods, notwithstanding that cost-benefit analysis requires more refined and accurate data to provide precise and locally adapted options.

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Pós-graduação em Engenharia Mecânica - FEG

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Pós-graduação em Engenharia Elétrica - FEIS

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The relentless pursuit for materials containing rare earth ions with photoluminescent properties has led to several studies with applications in the development of new technologies. The main focus of this work is the preparation of Er3+-doped polycrystalline Y2O3 with photoluminescent properties using PEG as an organic precursor and heat-treated at different temperatures. The methodology used in this synthesis is highly attractive due to its high feasibility for improved technology and low cost for preparing materials. The behavior of the viscous resin has been evaluated and the final compounds exhibited the formation of a cubic polycrystalline phase, which is able to support variations in Er3+ doping concentrations up to 10 mol%, without significant changes in the polycrystalline parameters. The values of the nanocrystallite size calculated by Scherrer's equation showed direct dependence on the heat-treatment temperature as well as the Er3+ concentration. Intense emission in the visible region under excitation at 980 nm was attributed to an upconversion phenomenon assigned to the intraconfigurational f-f transitions of Er3+ ions. The upconversion mechanism was investigated and it was demonstrated that the higher intense emission in the red region in comparison to the emission in the green region is related to the crystallite size. The studies about the intensity showed the dependence of upconversion emission of power source, indicating that two-photon are responsible for the green and red photoluminescence. These polycrystalline materials exhibit properties that make them promising for use in solar energy systems, C-telecom band or solid-state laser devices. (C) 2014 Elsevier B.V. All rights reserved.

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This paper presents a mixed-integer quadratically-constrained programming (MIQCP) model to solve the distribution system expansion planning (DSEP) problem. The DSEP model considers the construction/reinforcement of substations, the construction/reconductoring of circuits, the allocation of fixed capacitors banks and the radial topology modification. As the DSEP problem is a very complex mixed-integer non-linear programming problem, it is convenient to reformulate it like a MIQCP problem; it is demonstrated that the proposed formulation represents the steady-state operation of a radial distribution system. The proposed MIQCP model is a convex formulation, which allows to find the optimal solution using optimization solvers. Test systems of 23 and 54 nodes and one real distribution system of 136 nodes were used to show the efficiency of the proposed model in comparison with other DSEP models available in the specialized literature. (C) 2014 Elsevier Ltd. All rights reserved.

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

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The biomass gasification systems have been used for a long time and prove to be a good alternative to the generation of energy problems. This type of management requires a simple installation and maintenance which gives them a high availability. In Biomass project via Call CTEnerg 33/2006-1, funded by the Ministry of Science and Technology - MCT - Brazil, the Group Energy Systems Optimization – GOSE - at FEG - UNESP built and tested two prototypes of gasifiers. These is fed with 25 kg / h of dry wood (chips), and 50 Nm3 / h of air to produce gas at a flow rate of approximately 70 Nm3 / h of wood (syngas) at a temperature approximately 600 ° C. In this work of graduation, studies were conducted on the materials used in both the gasifier as well as cleaning the filter synthesis gases. The system of gas cleaning and conditioning is vital to ensure the life of the Internal Combustion Engine. In this case the studies of different filters for small gasification systems (properties, materials used, characteristics, types, etc.) are very relevant to its use in the prototype of the college campus. Were also performed a technical and economic analysis of a cogeneration system that consists in the combination of the downdraft gasifier studied in this work, an internal combustion engine, two heat exchangers and a SRA (absorption system refrigerator). Were calculated the costs of electricity generation, hot water and cold water. Finally, we analyzed the economic feasibility of the project

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)