Eduardo F. A. Silva

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This paper proposes a new method for binarization of digital documents. The proposed approach performs binarization by using a heuristic algorithm with two different thresholds and the combination of the thresholded images. The method is suitable for binarization of complex background document images. In experiments, it obtained better results than(More)
Information Extraction (IE) aims to extract from textual documents only the relevant data required by the user. In this paper, we propose a hybrid machine learning approach for IE on semi-structured texts that combines conventional text classification techniques and Hidden Markov Models (HMM). In this approach, a text classifier technique generates an(More)
This paper deals with automatic recognition of real bank checks. A new approach is proposed to read the numerical amount field from bank checks, considering the numeric value and the different delimiters that might exist in that field. The proposal combines different neural networks classifiers to perform the recognition. Experimental results have shown(More)
The fast growth of electronic text collections (in particular, the Web) and the diversity of available documents immensely increased the difficulty to retrieve relevant documents in an efficient way. A variety of Web search engines have been built to help users in this task. These systems, however, lack precision in the retrieved documents. Different(More)
The Sn-W Panasqueira mine, in activity since the mid-1890s, is one of the most important economic deposits in the world. Arsenopyrite is the main mineral present as well as rejected waste sulphide. The long history is testified by the presence of a huge amount of tailings, which release considerable quantities of heavy metal(loid)s into the environment.(More)
Conventional prestack time-migration velocity analysis is designed to estimate diffraction time functions in a fixed azimuthal direction from narrow-azimuth reflection data. Therefore, it can build accurate 3D migration operators only if the subsurface is isotropic (or azimuthally isotropic) and laterally homogeneous. Here, we extend time-migration(More)
Ria de Aveiro is a mesotidal coastal lagoon with one of the largest continuous salt marshes in Europe. The objective of this work was to assess C, N and P stocks of Spartina maritima (low marsh pioneer halophyte) and Juncus maritimus (representative of mid-high marsh halophytes) combined with the contribution of Halimione portulacoides, Sarcocornia(More)
Geochemical mapping is the base knowledge to identify the regions of the planet with critical contents of potentially toxic elements from either natural or anthropogenic sources. Sediments, soils and waters are the vehicles which link the inorganic environment to life through the supply of essential macro and micro nutrients. The chemical composition of(More)