Browsing by Subject "Tracking"

Now showing 1 - 3 of 3
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    Open Access
    Evolution of web tracking protection in Chrome
    (2023-11-08) Pan, Ronghao; Ruiz-Martínez, Antonio; Ingeniería de la Información y las Comunicaciones
    In our society, protecting users’ privacy is of utmost importance, especially when users access websites. Increased awareness of privacy concerns has led web browsers to implement new mechanisms to improve privacy while browsing the Internet. In each new version of web browsers, it is claimed that they provide better improvements to protect our privacy. However, there is no analysis of these improvements. To cope with this issue, in this paper, we present an analysis of the privacy of different versions of the Chrome web browser. This analysis is based on the PrivacyScanner tool, which we have improved with the detection of additional tracking techniques. Our findings reveal that tracking protection has seen modest enhancements (namely, between Chrome version 83 and 90, we observed a 7.55% reduction in trackers and 4.76% decrease in Google Analytics elements). Therefore, despite these improvements, there is still ample room for further enhancement.
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    Publication
    Open Access
    GPU-based processing of Hartmann-Shack images for accurate and high-speed ocular wavefront sensing
    (Elsevier, 2019-02) Mompeán, J.; Aragón, J.L.; Prieto, P.; Artal, P.; Ingeniería y Tecnología de Computadores
    Hartmann–Shack aberrometry is a widely used technique in the field of visual optics but, high-speed and accurate processing of Hartmann–Shack images can be a computationally expensive/resource intensive task. While some advancements have been made in achieving high-performance processing units, they have not been specifically designed for processing Hartmann–Shack images of the human eye with Graphics Processing Units. In this work, we present the first full-Graphics Processing Unit implementation of a Hartmann–Shacksensor algorithm aimed at accurately measuring ocular aberrations at a high speed from high-resolution spot pattern images. The proposed algorithm, called PaPyCS (Parallel Pyramidal Centroid Search), is inherently parallel and performs a very robust centroid search to avoid image noise and other artifacts. This is a field where the use of Graphics Processing Units have not been exploited despite the fact that they can boost Adaptive Optics systems and related closed-loop approaches. Our proposed implementation achieves processing speeds of 380 frames per second for high resolution (1280x1280 pixels) images, in addition to showing a high resilience to system and image artifacts that appear in Hartmann–Shack images from human eyes: more than 98% of the Hartmann–Shack images, with aberrations of up to 4m Root Mean Square for a 5.12mm pupil diameter, were measured with less than 0.05m Root Mean Square Error, which is basically negligible for ocular aberrations.
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    Publication
    Open Access
    Validity and reliability of an eight antennae ultra-wideband local positioning system to measure performance in an indoor environment
    (Taylor & Francis, 2020-11-18) Bastida-Castilla, Alejandro; Gómez-Carmona, Carlos David; Rico-González, Markel; Pino Ortega, José; Actividad Física y Deporte
    oad and positioning. One of the most important parameters to guarantee accurate measurements with radiofrequency systems is the number of reference nodes used to calculate player position. However, the accuracy of ultra-wideband (UWB) technology has only been analysed with 6 antennae. So, the purpose of the present study was to analyse the accuracy and inter-unit reliability of an UWB system with eight antennae. Three well-trained males covered 18 trajectories for the analysis of x- and y- coordinate accuracy assessment related to the positional variation among eight antennae UWB data and lines on a basketball court. This was achieved using geographical information system mapping software that calculated, for each interval and participant, the distance from the main axis of locomotion and the opposite side of the field every 0.5 s. The results showed that this is a valid system (Mean = 0.03 m; magnitude differences = 0.21% with real measures as reference; % CV <1% in all cases) for measuring locomotion and positioning. Besides, the inter-unit, test-retest and inter-subject analysis did not influence the reliability results. So, an eight antennae UWB system can be considered suitable for locomotion and positioning in an indoor environment.