63 resultados para spatial clustering algorithms


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This paper presents an embryo of a literary guide on the Carnation Revolution to be explored for educational historical excursions other than leisure and tourism. We propose a historical trail through the centre of Lisbon, city of the Carnation Revolution, called Walk through the Revolution. The trail aims to reinforce collective memory about the major events that occurred in the early moments leading to the coup. The trail is made up by nine places of rememberance, for which literary excerpts are suggested and which are supported by a digital research procedure. A set of seven fixed and observer-independent categories are used to analyse the literary contents of 23 literary works published up to 2013. These literary works refer to events that happened between the eve of April 25 and May 1, 1974. At the same time, literary descriptions are explored using a spatial approach in order to define the literary geography of the most iconic military actions and popular demonstrations that occurred in Lisbon and the surroundings. The literary geography and the cartography of the historical events are then compared. Data analysis and visualization benefit from the use of standardised and quantitative methods, including basic statistics and geographic information systems.

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This study focuses on the implementation of several pair trading strategies across three emerging markets, with the objective of comparing the results obtained from the different strategies and assessing if pair trading benefits from a more volatile environment. The results show that, indeed, there are higher potential profits arising from emerging markets. However, the higher excess return will be partially offset by higher transaction costs, which will be a determinant factor to the profitability of pair trading strategies. Also, a new clustering approach based on the Principal Component Analysis was tested as an alternative to the more standard clustering by Industry Groups. The new clustering approach delivers promising results, consistently reducing volatility to a greater extent than the Industry Group approach, with no significant harm to the excess returns.

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Remote sensing - the acquisition of information about an object or phenomenon without making physical contact with the object - is applied in a multitude of different areas, ranging from agriculture, forestry, cartography, hydrology, geology, meteorology, aerial traffic control, among many others. Regarding agriculture, an example of application of this information is regarding crop detection, to monitor existing crops easily and help in the region’s strategic planning. In any of these areas, there is always an ongoing search for better methods that allow us to obtain better results. For over forty years, the Landsat program has utilized satellites to collect spectral information from Earth’s surface, creating a historical archive unmatched in quality, detail, coverage, and length. The most recent one was launched on February 11, 2013, having a number of improvements regarding its predecessors. This project aims to compare classification methods in Portugal’s Ribatejo region, specifically regarding crop detection. The state of the art algorithms will be used in this region and their performance will be analyzed.