Examinando por Autor "Guerrero Curieses, A"

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A New Method for Single-Step Robust Post-Processing of Flow Color Doppler M-Mode Images Using Support Vector Machines
(2009-06-15T10:08:10Z) Conde Pardo, P; Guerrero Curieses, A; Rojo-Álvarez, José Luis; Yotti, R; Requena Carrión, J; Antoranz, José Carlos; Bermejo, Javier
Intra-cardiac pressure gradients (ICPG) are usually es timated by post-processing of flow Color Doppler M-mode images (CDMMI) by using a sequence of processing steps. We propose a novel image processing method which gives a single-step approximation of the ICPG image, based on a simple, yet specifically developed, Support Vector Machine (SVM) algorithm. Our method only requires the SVM estimation of the blood velocity from the CDMMI. Given that ICPG images are obtained by deterministic operators (Euler's momentum equation) on the blood velocity, the ICPG estimation is a simple model that consists of the same coefficients and the operator applied to the Mercer's kernel. A diverse-width Mercer's kernel is proposed, as an alternative to conventional Radial Basis Function kernel. Simulations on a synthetic model and approximations of a real example image, trained with up to 10% of the pixels, show the possibilities of this new single-step postprocessing method.
Nonparametric Model Comparison and Uncertainty Evaluation for Signal Strength Indoor Location.
(2009-06-15T10:23:01Z) Figuera Pozuelo, Carlos; Mora Jimenez, I; Guerrero Curieses, A; Rojo-Álvarez, José Luis; Everss, E; Wilby, M; Ramos López, J
Indoor Location (IL) using Received Signal Strength (RSS) is receiving much attention, mainly due to its ease of use in deployed IEEE 802.11b (WiFi) wireless networks. Fingerprinting is the most widely used technique. It consists of estimating position by comparison of a set of RSS measurements, made by the mobile device, with a database of RSS measurements whose locations are known. However, the most convenient data structure to be used, and the actual performance of the proposed fingerprinting algorithms, are still controversial. In addition the statistical distribution of indoor RSS is not easy to characterize. Therefore, we propose here the use of nonparametric statistical procedures for diagnosis of the fingerprinting model, specifically: (1) A non parametric statistical test, based on paired bootstrap resampling, for comparison of different fingerprinting models; (2) New accuracy measurements (the uncertainty area and its bias) which take into account the complex nature of the fingerprinting output. The bootstrap comparison test and the accuracy measurements are used for RSS-IL in ourWiFi network, showing relevant information relating to the different fingerprinting schemes that can be used.
On the Performance of Kernel Methods for Skin Color Segmentation
(2009-07-28T09:37:47Z) Guerrero Curieses, A; Rojo-Álvarez, José Luis; Conde Pardo, P; Landesa Vázquez, I; Ramos López, J; Alba Castro, L