Percorrer por autor "Silva, Hugo"
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- Autonomous Surface Vehicle Docking Manoeuvre with Visual InformationPublication . Martins, Alfredo; Almeida, José Miguel; Ferreira, Hugo; Silva, Hugo; Dias, Nuno; Silva, EduardoThis work presents a hybrid coordinated manoeuvre for docking an autonomous surface vehicle with an autonomous underwater vehicle. The control manoeuvre uses visual information to estimate the AUV relative position and attitude in relation to the ASV and steers the ASV in order to dock with the AUV. The AUV is assumed to be at surface with only a small fraction of its volume visible. The system implemented in the autonomous surface vehicle ROAZ, developed by LSA-ISEP to perform missions in river environment, test autonomous AUV docking capabilities and multiple AUV/ASV coordinated missions is presented. Information from a low cost embedded robotics vision system (LSAVision), along with inertial navigation sensors is fused in an extended Kalman filter and used to determine AUV relative position and orientation to the surface vehicle The real time vision processing system is described and results are presented in operational scenario.
- Estimation of Rabbit Pancreas Dispersion Between 400 and 1000 nmPublication . Martins, Inês; Silva, Hugo; Tuchin, Valery; Oliveira, LuísCurrent biophotonics methods cover the entire optical spectrum from the deep ultraviolet to the terahertz. To optimize such methods for diagnostic and therapeutic applications, the need to obtain the wideband dispersion of tissues is high. The pancreas is a very important organ in the human body, since it produces insulin and its malfunction may induce diabetes. A reduced number of biophotonics publications regarding the pancreas is available, meaning that studies to determine its optical properties and their variation during optical clearing treatments are necessary. Considering this fact, we used the total internal reflection method to measure the refractive index of the rabbit pancreas for wavelengths between 400 and 850 nm. The experimental results allowed to calculate the pancreas dispersion with the Cauchy, Conrady and Cornu equations. It was observed that all those equations provided good data fitting in the spectral range of the measurements, but differences were observed outside these limits. Considering the wavelength of 633 nm, the mean value from the three dispersions was 1.3521, while the one published for porcine pancreas is 1.3517. The dispersion calculated with the Conrady equation does not present a fast decreasing behavior for shorter wavelengths as the ones calculated with the Cauchy and Cornu equations, but comparing these curves with a dispersion for a tissue-like material, all seem to have good agreement. © 2021 Journal of Biomedical Photonics & Engineering
- Facial emotion recognition: virtual reality program for facial emotion recognition—a trial program targeted at individuals with schizophreniaPublication . Souto, Teresa; Silva, Hugo; Leite, Ângela; Batista, Alexandre; Queirós, Cristina; Marques, António da SilvaPeople with severe mental illness (SMI), schizophrenia in particular, show considerable functional impairment in emotional recognition and social perception, which negatively affects interpersonal relationships and social functioning. Owing to its ecological validity, virtual reality (VR) has been observed to improve both assessment and training of emotional recognition skills of people with SMI. This article includes two studies: (a) a descriptive study on the Virtual Reality program for Facial Emotion Recognition (VR-FER) and (b) an empirical study that presents the results of the application of the VR-FER’s first module. For the second study, data were collected using two samples: a group of 12 people with schizophrenia and a reference group of 12 people who were mentally healthy. Data analysis comprised descriptive (mean, standard deviation) and inferential statistics (Mann–Whitney U test). Results showed that the first group presented a lower number of correct answers and a higher number of incorrect answers compared with the second group regarding facial emotion recognition (FER), thereby confirming the need to develop strategies to improve emotional recognition and social perception in people with schizophrenia. VR-FER is regarded a strategic training program for FER, using latest technology and following rehabilitation guidelines for SMI.
- Forest fire detection with a small fixed wing autonomous aerial vehiclePublication . Martins, Alfredo; Almeida, José; Almeida, Carlos; Figueiredo, André; Santos, Filipe; Bento, Domingos; Silva, Hugo; Silva, EduardoIn this work a forest fire detection solution using small autonomous aerial vehicles is proposed. The FALCOS unmanned aerial vehicle developed for remote-monitoring purposes is described. This is a small size UAV with onboard vision processing and autonomous flight capabilities. A set of custom developed navigation sensors was developed for the vehicle. Fire detection is performed through the use of low cost digital cameras and near-infrared sensors. Test results for navigation and ignition detection in real scenario are presented.
- Invasive and minimally invasive optical detection of pigment accumulation in brain cortexPublication . Oliveira, Luís; Gonçalves, Tânia; Pinheiro, Maria; Fernandes, Luís; Martins, Inês; Silva, Hugo; Oliveira, Hélder; Tuchin, Valery; Oliveira, LuísThe estimation of the spectral absorption coefficient of biological tissues provides valuable information that can be used in diagnostic procedures. Such estimation can be made using direct calculations from invasive spectral measurements or though machine learning algorithms based on noninvasive or minimally invasive spectral measurements. Since in a noninvasive approach, the number of measurements is limited, an exploratory study to investigate the use of artificial generated data in machine learning techniques was performed to evaluate the spectral absorption coefficient of the brain cortex. Considering the spectral absorption coefficient that was calculated directly from invasive measurements as reference, the similar spectra that were estimated through different machine learning approaches were able to provide comparable information in terms of pigment, DNA and blood contents in the cortex. The best estimated results were obtained based only on the experimental measurements, but it was also observed that artificially generated spectra can be used in the estimations to increase accuracy, provided that a significant number of experimental spectra are available both to generate the complementary artificial spectra and to estimate the resulting absorption spectrum of the tissue.
- Pontes entre Ensino Superior e Ensino Básico: Aprendizagem (Inter)Ativa sobre higiene das mãosPublication . Karpyuk, António; Garcia, Bruna; Santos, Diana; Silva, Hugo; Lamas, Maria Céu; Ferreira, Stephanie; Mota, Sandra; Amorim, Maria Manuela; Ribeiro Lamas, Maria do Céu; Lopes Ferreira, Stephanie; Amorim Sousa, Maria ManuelaNo âmbito da formação dos estudantes da licenciatura Ciências Biomédicas Laboratoriais (E2S, P. Porto), enquanto futuros profissionais de saúde, é fundamental promover experiências pedagógicas que coligem o conhecimento técnico-científico à capacidade de comunicação. A atividade sobre Higiene das Mãos foi concebida e dinamizada por 4 estudantes do ensino superior (ES) para 30 crianças do Ensino Básico (3º e 4º ano), constituiu uma estratégia de intervenção comunitária orientada para a promoção da literacia em saúde. Atividade lúdica e interativa, adaptada à faixa etária, sensibilizou crianças para a importância da higiene das mãos através de exposição teórica, jogos, demonstração de técnicas, simulações e sementeiras. A avaliação pré e pós-sessão demonstrou resultados positivos. Simultaneamente, constituiu uma oportunidade formativa para estudantes do ES, promovendo competências transversais como comunicação em saúde, pensamento crítico e adaptabilidade. Esta prática pedagógica evidenciou-se como estratégica na promoção da saúde individual e coletiva, sendo valorizada pelos estudantes em relatório como modelo eficaz na conceção de intervenções educativas em saúde.
- Probabilistic Egomotion for Stereo Visual OdometryPublication . Silva, Hugo; Bernardino, A.; Silva, EduardoWe present a novel approach of Stereo Visual Odometry for vehicles equipped with calibrated stereo cameras. We combine a dense probabilistic 5D egomotion estimation method with a sparse keypoint based stereo approach to provide high quality estimates of vehicle’s angular and linear velocities. To validate our approach, we perform two sets of experiments with a well known benchmarking dataset. First, we assess the quality of the raw velocity estimates in comparison to classical pose estimation algorithms. Second, we added to our method’s instantaneous velocity estimates a Kalman Filter and compare its performance with a well known open source stereo Visual Odometry library. The presented results compare favorably with state-of-the-art approaches, mainly in the estimation of the angular velocities, where significant improvements are achieved.
- Probabilistic Stereo Egomotion TransformPublication . Silva, Hugo; Bernardino, A.; Silva, EduardoIn this paper we propose a novel fully probabilistic solution to the stereo egomotion estimation problem. We extend the notion of probabilistic correspondence to the stereo case which allow us to compute the whole 6D motion information in a probabilistic way. We compare the developed approach against other known state-of-the-art methods for stereo egomotion estimation, and the obtained results compare favorably both for the linear and angular velocities estimation.
- ROAZ and ROAZ II Autonomous Surface Vehicle Design and ImplementationPublication . Martins, Alfredo; Ferreira, Hugo; Almeida, Carlos; Silva, Hugo; Almeida, José Miguel; Silva, EduardoThe design and implementation of the ROAZ and ROAZ II autonomous surface vehicles (ASV) is presented. These systems were developed at Autonomous Systems Lab, ISEP/IPP – Instituto Superior de Engenharia do Porto under a research program in marine robotics. With multiple applications either in river and estuarine environments or in the sea, the system applications in search and rescue operations are addressed and were taken in consideration for the overall system design. Mechanical design issues are discussed. Hardware, software and implementation status are described along with the control and navigation system architecture. The real time vision processing system is described and results are presented in operational scenario.
- Spectral Optical Properties of Rabbit Brain Cortex between 200 and 1000 nmPublication . Gonçalves, Tânia M.; Martins, Inês; Silva, Hugo; Tuchin, Valery V.; Oliveira, LuísThe knowledge of the optical properties of biological tissues in a wide spectral range is highly important for the development of noninvasive diagnostic or treatment procedures. The absorption coefficient is one of those properties, from which various information about tissue components can be retrieved. Using transmittance and reflectance spectral measurements acquired from ex vivo rabbit brain cortex samples allowed to calculate its optical properties in the ultraviolet to the near infrared spectral range. Melanin and lipofuscin, the two pigments that are related to the aging of tissues and cells were identified in the cortex absorption. By subtracting the absorption of these pigments from the absorption of the brain cortex, it was possible to evaluate the true ratios for the DNA/RNA and hemoglobin bands in the cortex—12.33-fold (at 260 nm), 12.02-fold (at 411 nm) and 4.47-fold (at 555 nm). Since melanin and lipofuscin accumulation increases with the aging of the brain tissues and are related to the degeneration of neurons and their death, further studies should be performed to evaluate the evolution of pigment accumulation in the brain, so that new optical methods can be developed to aid in the diagnosis and monitoring of brain diseases.