860 resultados para Seasonality and trends
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Includes bibliography
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Includes bibliography
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This work presents the evaluation of different power electronic integrated converters suitable for photovoltaic applications, in order to reduce complexity and improve reliability. The rated voltages available in Photovoltaic (PV) modules have usually low values for applications such as regulated output voltages in stand-alone or grid-connected configurations. In these cases, a boost stage or a transformer will be necessary. Transformers have low efficiencies, heavy weights and have been used only when galvanic isolation is mandatory. Furthermore, high-frequency transformers increase the converter complexity. Therefore, the most usual topologies use a boost stage and one inverter stage cascaded. However, the complexity, size, weight, cost and lifetime might be improved considering the integration of both stages. In this context, some integrated converters are analyzed and compared in this paper in order to support future evaluations and trends for low power single-phase inverters for PV systems. Power decoupling, MPPT and Tri-State modulations are also considered. Finally, simulation and experimental results are presented and compared for the analyzed topologies. © 2011 IEEE.
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Includes bibliography
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After nearly 80 years since the construction of its core, represented today by the city's central area, Londrina, located in the state of Parana, has the appearance of a new city but its features and trends of planning policies depict the bad examples of Brazilian cities. With a booming urban growth, from north to south of the county, the urban interstices represented by big voids in the middle of the city created speculation and the concept of an ideal city slowly disappeared. With a metropolitan appearance and, at the same time, with small town aspects, Londrina stands out as an automobile-oriented city, a fact that has impacted the livelihood of the population, generating environmental impacts for all social classes. This paper discusses how the form of occupation in Londrina, characterized by the sprawl phenomenon and its relation to car preference as a mode of transportation has generated urban environmental impacts. It was concluded that the choice of using cars in Londrina, as well in other medium-sized Brazilian cities studied by the comparative method, has increased and has generated bottlenecks in traffic. As a consequence, there is a constant expropriation of properties for widening roads and at the same time, the presence of various densities and urban voids that form an uneven urban space and an obstacle to efficient urban planning. © 2012 WIT Press.
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Includes bibliography
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Includes bibliography
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Includes bibliography
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This and subsequent issues of the Bulletin provide an account of recent events and trends in the transport sector in Latin America and the Caribbean. This edition deals with aspects relating to multimodal transport, maritime transport and ports.
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The previous edition of the FAL bulletin presented the price indices of maritime transport in three main market segments. This edition includes an analysis of the maritime cycle and trends in the transport capacity of the routes that in turn serve the routes of Latin America and the Caribbean.
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This edition of the FAL Bulletin tells of recent events and trends in urban transport, railways and highway maintenance in Latin America and the Caribbean.
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Incluye Bibliografía
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• Editorial remarks.-- Open discussion: Tariffs and subsidies: the current situation and trends in the region ; State-owned utilities and the flight from public law: challenges and trends ; Challenges and opportunities in access to water and sanitation in rural areas.-- Meetings: Proposals based on the Water and Environment Initiative consensuses.-- News of the Network: Peru’s Compensation Mechanisms for Ecosystem Services Act ; Ecuador’s Act on Water Resources and Water Use and Exploitation ; The environmental dynamics of groundwater in Mexico ; The Water Citizenship Programme in the province of Mendoza, Argentina.-- Internet and WWW News
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The prime movers behind the prehistoric colonization of Remote Oceania, and in particular the large c. 2000-year temporal gap (i.e. long pause') seen between West and East Polynesia, has long been major point of interest in the Pacific. To address these events and the processes that may have led to the known chronological disparity of these diasporas, we present results from two different, but equally powerful, analytical tools which are used to examine Polynesian seafaring capabilities and trajectories. The first is a statistical model known as Seascape, which simulates voyages, while the second uses ease of eastward travel estimates based on land distribution and wind pattern analysis. These analyses were done with the goal of determining the potential role of environmental factors in the colonization process, particularly as they relate to the long pause. We show that the eastern boundary of West Polynesia, the limit of the initial colonization pulse, is marked by a discontinuity in land distribution, where the distances travelers would have to cross in order to reach islands further to the east become significantly larger. At the same time, in West Polynesia, the frequency and intensity of winds favorable to eastward displacement decrease continuously from west to east. As far as winds are concerned, eastward travel in West Polynesia is favored in the northern and southern areas and much more difficult across the central portion. Favorable winds have a clear seasonality, and eastward displacement along the northern area is much easier under El Nino conditions. Voyaging simulations show that intentional eastward voyages departing from Tonga and Samoa, when undertaken with vessels capable of sailing efficiently against the wind, afford a viable route toward several island groups in East Polynesia, with trips starting in Samoa having a higher probability of success.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)