2011
Autores
Oliveira, R; Rodrigues, F; Martins, P; Moura, JP;
Publicação
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Abstract
In the past, several approaches have been devised to semi- automate the multidimensional design (MDD) of Data Warehouse (DW) projects. Such approaches highly contribute to more expertise- independent and deterministic MDD results. Among them, only the Dimensional Templates Approach (DTA) focuses on solving the critical resource containment problems of DW prototypes. Originally, the DTA allows solely the generation of basic MDDs. In this paper, we depict an extension to address complex MDD issues. These include (i) date/time hierarchies, (ii) many-to-many relationships, (iii) hierarchically structured data and (iv) coverage facts. The proposed enhancements, including a rebuilt generation algorithm, allow more accurate and broadening results than the original DTA. Throughout the paper, references are made to a real case study to which the improved DTA has been applied using two developed prototype tools. © 2011 Springer-Verlag.
2011
Autores
Sousa, AMR; Xavier, J; Vaz, M; Morais, JJL; Filipe, VMJ;
Publicação
STRAIN
Abstract
This study presents a method to measure the displacement fields on the surface of planar objects with sub-pixel resolution, by combining image correlation with a differential technique. First, a coarse approximation of the pixel level displacement is obtained by cross-correlation (CC). Two consecutive images, taken before and after the application of a given deformation, are recursively split in sub-images, and the CC coefficient is used as the similarity measure. Secondly, a fine approximation is performed to assess the sub-pixel displacements by means of an optical flow method based on a differential technique. To validate the effectiveness and robustness of the proposed method, several numerical tests were carried out on computer-generated images. Moreover, real images from a static test were also processed for estimating the displacement resolution. The results were compared with those obtained by a commercial digital image correlation code. Both methods showed similar and reliable results according to the proposed tests.
2011
Autores
Sousa, AMR; Xavier, J; Morais, JJL; Filipe, VMJ; Vaz, M;
Publicação
OPTICS AND LASERS IN ENGINEERING
Abstract
In this paper, a digital image correlation (DIC) method coupling cross-correlation with spatio-temporal differential techniques was proposed for assessing discontinuous displacement fields. The accuracy and robustness of the algorithm was assessed on a set of numerical tests by processing computer generated speckled-pattern images. Fracture mechanical tests in mode I were considered, in which both in-plane and out-of-plane rigid-body movements were taken into account. The ability for recovering the analytical asymptotic displacement field in mode I was analysed, and stress intensity factor, crack opening displacement and crack tip location were used as quantitative parameters for validation purposes. Throughout these tests, the results obtained with the proposed method were systematically compared to the ones from Aramis DIC-2D commercial code. Globally, the results computed from both methods are in good agreement with reference values. However, due to the high spatial resolution (point-wise characteristic), a better matching of the displacements in the neighbour of discontinuities could be obtained by the proposed method.
2011
Autores
Costa, P; Fernandes, H; Vasconcelos, V; Coelho, P; Barroso, J; Hadjileontiadis, L;
Publicação
HUMAN-COMPUTER INTERACTION: TOWARDS MOBILE AND INTELLIGENT INTERACTION ENVIRONMENTS, PT III
Abstract
Assistive technology enables people to achieve independence in the accomplishment of their daily tasks and enhance their quality of life. Visual information is the basis for most navigational tasks, so visually impaired individuals are at disadvantage due to the lack of information or given insufficient information about their surrounding environment. With the recent advances in inclusive technology it is possible to extend the support given to people with visual disabilities during their mobility. In this context we propose a new algorithm to recognize landmarks suitably placed on sidewalks. The proposed algorithm uses a combination of Peano-Hilbert Space Filling Curves for dimension reduction of image data and Ensemble Empirical Mode Decomposition (EEMD) to pre-process the image, resulting on a fast and efficient recognition method and revealing a promising solution.
2011
Autores
Trigo, A; Varajão, J; Barroso, J; Soto-Acosta, P; Molina-Castillo, FJ; Gonzalvez-Gallego, N;
Publicação
- Managing Adaptability, Intervention, and People in Enterprise Information Systems
Abstract
2011
Autores
Charisis, VS; Hadjileontiadis, LJ; Barroso, J; Sergiadis, GD;
Publicação
2012 25TH INTERNATIONAL SYMPOSIUM ON COMPUTER-BASED MEDICAL SYSTEMS (CBMS)
Abstract
Wireless capsule endoscopy (WCE) is a revolutionary, patient-friendly imaging technique that enables non-invasive visual inspection of the patient's digestive tract, especially small intestine. However, the time-consuming task of reviewing the endoscopic data a burden for the physicians. This limitation was the propose a novel strategy for automatic discrimination of WCE images related to ulcer, the most common finding of digestive tract Towards this direction, WCE data are processed with Bidimensional Ensemble Empirical Mode Decomposition to reveal their inherent structural components, and also to reconstruct a new refined image. Then, texture information is extracted by analyzing the intrinsic second/higher-order correlation of the original image and by calculating the lacunarity index of the refined image. Experimental results demonstrated promising classification accuracy (97%) exhibiting high potential towards a complete computer-aided diagnosis system.
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