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23 results on '"Viriato, Nuno"'

3. A LiDAR based obstacle detection framework for railway

Author

Dias Susana, Sousa Pedro, Afonso Francisco, Viriato Nuno, Tavares Paulo, and Moreira Pedro

Subjects
Physics, QC1-999
Abstract

Obstacle detection on the railway, a crucial operational safety concern, is a complex task that encompasses a multitude of challenges. While Machine Learning (ML) algorithms are commonly employed in analogous applications such as autonomous car driving [1] [2], the railway field faces a significant barrier due to the scarcity of available data (particularly images), rendering conventional ML approaches impractical. In response to this challenge, this study proposes and evaluates a framework which uses LiDAR (Light Detection and Ranging) data for obstacle detection on the railways. The framework aims to address the limitations posed by image data scarcity while enhancing operational safety in railway environments. The developed methodology combines the use of a long-range LiDAR capable of detecting obstacles at distances of up to 500 meters, with the train’s GPS (Global Positioning System) coordinates to accurately determine its position relative to detected obstacles. The LiDAR data is processed using a data fusion approach, where pre-existing knowledge regarding the track topography is combined with a clustering algorithm, specifically DBSCAN (Density-based spatial clustering of applications with noise), to identify and classify potential obstacles at a pre-defined distance. Tests of the proposed framework were conducted within the confines of a moving locomotive, specifically the CP 2600-2620 series, along a designated section of the Contumil-Leixões line. These tests served to validate the effectiveness and feasibility of the approach under real-world operating conditions. Overall, the utilization of LiDAR data coupled with advanced algorithms presents a promising avenue for enhancing obstacle detection capabilities in railway operations. By overcoming the challenges associated with data scarcity, this framework holds the potential to significantly improve operational safety and efficiency within railway networks. Further research and testing are warranted to validate the framework’s performance across diverse railway environments and operating conditions.

Published
2024
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11. 3D Device for Forces in Swimming Starts and Turns

Author

de Jesus, Karla, primary, Mourão, Luis, additional, Roesler, Hélio, additional, Viriato, Nuno, additional, de Jesus, Kelly, additional, Vaz, Mário, additional, Fernandes, Ricardo, additional, and Vilas-Boas, João Paulo, additional

Published
2019
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13. Aplicação do RDC (research diagnostic criteria) no diagnóstico precoce de DTM

Author

Gomes, Viriato Nuno Barbosa, Fonseca, Patrícia Alexandra Barroso da, and Baptista, André

Subjects
Diagnostic criteria, Joint pathology, temporomandibular disorders, Diagnóstico precoce, Articulação temporomandibular, Desordens temporomandibulares, Critérios de diagnóstico, Patologia articular, Early diagnosis, Ciências Médicas::Outras Ciências Médicas [Domínio/Área Científica], Temporomandibular joint
Abstract

Submitted by Cristina Afonso (cac@lisboa.ucp.pt) on 2017-03-14T16:32:11Z No. of bitstreams: 1 Tesefinal.pdf: 3353704 bytes, checksum: f6599f49a812c7e10be44fbab2587232 (MD5) Approved for entry into archive by Cristina Afonso (cac@lisboa.ucp.pt) on 2017-03-14T16:32:23Z (GMT) No. of bitstreams: 1 Tesefinal.pdf: 3353704 bytes, checksum: f6599f49a812c7e10be44fbab2587232 (MD5) Made available in DSpace on 2017-03-14T16:32:23Z (GMT). No. of bitstreams: 1 Tesefinal.pdf: 3353704 bytes, checksum: f6599f49a812c7e10be44fbab2587232 (MD5) Previous issue date: 2016-12-16

Published
2016

15. FBG sensors application for residual stress measurement using the hole drilling method

Author

Braga, Daniel F.O., Silva, Ana C.F., Viriato, Nuno, Ribeiro, J.E., and Moreira, Pedro M.G.P.

Subjects
Hole drilling, Residual stress, Physics::Optics, FBG sensor, Astrophysics::Galaxy Astrophysics
Abstract

This work focus on the development of a new sensor for residual stress measurement using fiber optic Bragg sensors. A known stress field was induced on a specimen and results obtained from both the fiber optic Bragg sensors rosette and traditional electrical strain rosette were compared. Also a FEM model was used to confirm the obtained results.

Published
2013

17. Sistemas CAD-CAM em medicina dentária. Integração com métodos de análise de tensões

Author

Correia, André, Sampaio Fernandes, J.C., Campos, J.C. Reis, Vaz, M.A.P., Piloto, P.A.G., and Viriato, Nuno

Abstract

A evolução tecnológica das últimas décadas, dos sistemas de levantamento de forma, das preparações dentárias, do software de desenho virtual (0W), dos materiais dentários e máquinas de fresagem (CAM), levou ao desenvolvimento de vários sistemas CAD-CAM com aplicabilidade em Medicina Dentária (ex. Everestt Kavo, disponível na FMDUPJ). Nesse sentido o Grupo da Prótese Dentária e Oclusão da FMDUP desenvolveu uma colaboração interdisciplinar com o Laboratório de óptica e Mecânica Experimental (LOME) da FEUP no sentido de adoptar as tecnologias normalmente aplicadas em Engenharia para optimização de estruturas utilizadas em Próteses Dentárias. Foi então concebida uma metodologia de exportação dos ficheiros de desenho virtual para integração com os métodos de análise de tensões numéricos e experimentais, permitindo desta forma o estudo de situações compatíveis com a realidade clínica. Neste trabalho é apresentada uma aplicação desta metodologia em diversos trabalhos experimentais de análise de tensões em próteses parciais fixas dentárias.

Published
2010

18. Metal ceramic fixed partial denture: fracture resistance

Author

Piloto, P.A.G., Alves, Ana Maria Rodrigues, Correia, André, Campos, J.C. Reis, Fernandes, J.C. Sampaio, Vaz, M.A.P., and Viriato, Nuno

Abstract

Partially encased beam is a steel-concrete composite structure, made-up with a hot rolled profile and filled with concrete between flanges. Such structural element improves load-bearing capacity at elevated temperatures. Metal ceramic Fixed Partial Dentures (FPD) are suitable to increase fracture resistance presenting higher clinical longevity. This type of prosthesis is mainly used when a great number of teeth replacements are needed. The FPD under analysis is defined by a metallic infrastructure (titanium) and by a ceramic coating. The advantages of hybrid FPI) lie in their predictable biomechanical behavior versatility and cost. The main disadvantage is related to aesthetic functionality. Karlsson (1986), Lindquist & Karlsson (1998) and Palmqvist (1993) quantified the life time for hybrid FPD, referring lO years in service lo be a survival of break point. The connector design is of great importance to improve smooth stress pattern in the region between teeth. This region is also restrained by biological and aesthetic reasons, Ceramic material presents elevated failure rate in FPD due to brittleness. This work intends to predict fracture resistance to different loading conditions, using a smeared fracture approach (continuous damage mechanics), Results agree well with experimental evidence.

Published
2009

19. Experimental measurement of the displacement field on a mandible in vitro

Author

Lopes, Hernani, Ribeiro, J.E., Piloto, P.A.G., Viriato, Nuno, Monteiro, Jaime M., Campos, J.C. Reis, and Vaz, M.A.P.

Abstract

This paper presents an attempt to obtain the displacement field produced in a human mandible during the mastication. This information is of crucial importance in the stress estimation. Rubber bands fixed on mandible bone are used to simulate muscles and tendons being the load applied at the incisive teeth and controlled by a load cell. The temporomandibular joint and ligaments are implemented through the fixation of the mandible to a mechanic rig. The global boundary conditions were defined according to the anatomic model. The in-plane ESPI (Electronic Speckle Pattern interferometry) technique [1] is used for the measurement of flue global displacement field at mandible surface. The numerical simulation of the 3D modal mandible [2], which includes the cortical and spongeous bone, is performed using a commercial finite element method code, Ansys® [3J. The figure 1 shows the experimental results with ESPI and the numerical simulation.

Published
2009

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