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Campinas, Brazil

Dos Reis J.C.,University of Campinas | Bonacin R.,CTI Renato Archer | Baranauskas M.C.C.,University of Campinas
Lecture Notes in Business Information Processing | Year: 2011

Inclusive Social Network Services (ISN) represent an opportunity for ordinary people to access information and knowledge through the Web. Such systems should provide access for all, creating situations where users' diversity is respected and the access difficulties are minimized. The use of search mechanisms has been the main way to find information in the Web. However, such mechanisms are still built through lexical-syntactical processing resulting in barriers for many users to reach correct and valuable information. In ISN all people must have the possibility of recovering information that makes sense to them. For that, search engines in ISN should take into account the meanings created, shared and used by people through the use of the system. In this paper we prospect an inclusive search mechanism for ISN grounded in Semantic Web technologies combined with Organizational Semiotics concepts and methods. The conception of the proposed solution is based on experimental results that point out how to improve search mechanisms considering aspects related to social and digital inclusion. Such proposal aims to address and promote the participatory and universal access to knowledge. © 2011 Springer-Verlag Berlin Heidelberg. Source

Silveira G.,CTI Renato Archer | Silveira G.,French Institute for Research in Computer Science and Automation | Malis E.,French Institute for Research in Computer Science and Automation
International Journal of Computer Vision | Year: 2010

The fundamental task of visual tracking is considered in this work as an incremental direct image registration problem. Direct methods refer to those that exploit the pixel intensities without resorting to image features. We propose new transformation models and optimization methods for directly and robustly registering images (including color ones) of rigid and deformable objects, all in a unified manner. We also show that widely adopted models are in fact particular cases of the proposed ones. Indeed, the proposed general models combine various classes of image warps and ensure robustness to generic lighting changes. Finally, the proposed optimization method together with the exploitation of all possible image information allow the algorithm to achieve high levels of accuracy. Extensive experiments are reported to demonstrate that visual tracking can indeed be highly accurate and robust despite deforming objects and severe illumination changes. © 2010 Springer Science+Business Media, LLC. Source

Aldao C.M.,University of the Sea | Schipani F.,University of the Sea | Ponce M.A.,University of the Sea | Joanni E.,CTI Renato Archer | Williams F.J.,University of Buenos Aires
Sensors and Actuators, B: Chemical | Year: 2014

Conduction mechanisms in polycrystalline SnO2 thick sensing films were investigated by means of DC electrical resistance during heating-cooling cycles. Samples were maintained at relatively high temperatures in H2 or O2 ambient atmospheres before performing electrical measurements under vacuum or before performing XPS measurements in order to determine band bending. Results suggest that intergrains present Schottky barriers that are responsible for the observed conductivities regardless of gas pre-treatment. Oxygen diffusion modulates barrier widths affecting conductivity through tunneling transport. The electrical response to subsequent exposure to an oxygen atmosphere is consistent with our interpretation. © 2013 Elsevier B.V. All rights reserved. Source

Silveira G.,CTI Renato Archer
Robotics and Autonomous Systems | Year: 2014

This article investigates the problem of pose-based visual servoing whose equilibrium state is defined via a reference image. Differently from most solutions, this work directly exploits the pixel intensities without any feature extraction or matching. Intensity-based methods provide for higher accuracy and versatility. Another central idea of this work concerns the exploitation of the observability issue associated to monocular systems, which always occurs around the equilibrium. This overall framework allows for developing a family of new 3D visual servoing techniques with varying degrees of computational complexity and of prior knowledge. Importantly, they are arranged hierarchically from the simplest to the optimal ones, all in a unified scheme. Three new methods are then presented, and their closed-loop performances are experimentally assessed using a six degree-of-freedom robotic arm. As an additional contribution, these results refute the common belief that correct camera calibration and pose recovery are crucial to the accuracy of 3D visual servoing techniques. © 2014 Elsevier B.V. All rights reserved. Source

Ponce M.A.,University of the Sea | Ramirez M.A.,Paulista University | Schipani F.,University of the Sea | Joanni E.,CTI Renato Archer | And 2 more authors.
Journal of the European Ceramic Society | Year: 2015

In this work n-type CaCu3Ti4O12 (CCTO) thick films obtained by screen printing were studied. The role of the potential barrier characteristics (height and width) was considered in order to explain the electrical behavior. The electrical response was also analyzed considering the oxygen adsorption and subsequent diffusion into the grains at temperatures higher than 280°C. Tunnel currents were also calculated taking into account the donor concentration values for films in vacuum atmosphere. © 2014. Source

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