Vigilância da costa marítima utilizando radar de abertura sintética

Nesta tese apresenta-se uma nova técnica para solucionar a problemática da estimação de velocidade de embarcações em Radar de Abertura Sintética (SAR). A solução proposta combina duas técnicas já publicadas introduzindo como inovação, a Transformada de Radon. Esta transformada vai permitir estimar a posição do rasto que a embarcação gera à medida que se vai deslocando. Com a posição do objecto calculada é então possível estimar a sua distância ao rasto e assim a velocidade em range. Esta estimativa é limitada pelo Pulse Repetition Frequency (PRF) utilizado na missão SAR. Para a velocidade em azimute é usada uma técnica de Multilook que vai executar uma correlação cruzada entre dois look’s consecutivos. Esta operação permite estimar o desvio que um alvo sofreu de um look para outro. Medindo a frequência central de cada look utilizado é possível estimar a velocidade em azimute.

Integrated analysis of climate, soil, topography and vegetative growth in Iberian viticultural regions

The Iberian viticultural regions are convened according to the Denomination of Origin (DO) and present different climates, soils, topography and management practices. All these elements influence the vegetative growth of different varieties throughout the peninsula, and are tied to grape quality and wine type. In the current study, an integrated analysis of climate, soil, topography and vegetative growth was performed for the Iberian DO regions, using state-of-the-art datasets. For climatic assessment, a categorized index, accounting for phenological/thermal development, water availability and grape ripening conditions was computed. Soil textural classes were established to distinguish soil types. Elevation and aspect (orientation) were also taken into account, as the leading topographic elements. A spectral vegetation index was used to assess grapevine vegetative growth and an integrated analysis of all variables was performed. The results showed that the integrated climate-soil-topography influence on vine performance is evident. Most Iberian vineyards are grown in temperate dry climates with loamy soils, presenting low vegetative growth. Vineyards in temperate humid conditions tend to show higher vegetative growth. Conversely, in cooler/warmer climates, lower vigour vineyards prevail and other factors, such as soil type and precipitation acquire more important roles in driving vigour. Vines in prevailing loamy soils are grown over a wide climatic diversity, suggesting that precipitation is the primary factor influencing vigour. The present assessment of terroir characteristics allows direct comparison among wine regions and may have great value to viticulturists, particularly under a changing climate.

Phase correction for passive radar using targets of opportunity

This paper presents a novel phase correction technique for Passive Radar which uses targets of opportunity present in the target area as references. The proposed methodology is quite simple and enables the use of low cost hardware with independent oscillators for the reference and surveillance channels which can be geographically distributed. © 2014 IEEE.