2025
Autores
Campos, TD; Martins, M; Quyen, N; de Moura, MFSF; Dourado, N;
Publicação
THEORETICAL AND APPLIED FRACTURE MECHANICS
Abstract
A comprehensive understanding of the mechanisms underlying bone fatigue failure is crucial for advancing treatment strategies. In this regard, this study presents a novel approach to quantify crack propagation in cortical bone tissue through fatigue testing under mode I loading. To closely replicate real bone damage mechanisms, pre-cracked bone samples were subjected to cyclic loading. A compliance-based beam method and cubic B-spline interpolation method were employed to accurately extract fatigue coefficients and reduce experimental noise, yielding refined modified Paris law coefficients. A cohesive zone model for high-cycle fatigue was used to simulate crack propagation, capturing the nonlinear material response by means of the cohesive zone length, mimicking the non-negligible fracture process zone. The goal is to validate the followed experimental procedure. This study offers valuable insights into the fatigue and fracture mechanisms in cortical bone, providing a more accurate and realistic framework for characterizing fatigue life compared to previous methodologies. Coefficients produced from the cohesive model may be readily integrated into simulation tools commonly used in many areas of engineering, allowing biomechanical experts to create more robust designs that simulate actual world conditions for application in implants and orthopaedic structures.
2025
Autores
Matos, T; Rocha, JL; Martins, MS; Goncalves, LM;
Publicação
JOURNAL OF MARINE SCIENCE AND ENGINEERING
Abstract
The need for real-time and scalable oceanographic monitoring has become crucial for coastal management, marine traffic control and environmental sustainability. This study investigates the integration of sensor technology into marine cables to enable real-time monitoring, focusing on tidal cycles and wave characteristics. A 2000 m cable demonstrator was deployed off the coast of Portugal, featuring three active repeater nodes equipped with pressure sensors at varying depths. The goal was to estimate hourly wave periods using fast Fourier transform and calculate significant wave height via a custom peak detection algorithm. The results showed strong coherence with tidal depth variations, with wave period estimates closely aligning with forecasts. The wave height estimations exhibited a clear relationship with tidal cycles, which demonstrates the system's sensitivity to coastal hydrodynamics, a factor that numerical models designed for open waters often fail to capture. The study also highlights challenges in deep-water monitoring, such as signal attenuation and the need for high sampling rates. Overall, this research emphasises the scalability of sensor-integrated smart marine cables, offering a transformative opportunity to expand oceanographic monitoring capabilities. The findings open the door for future real-time ocean monitoring systems that can deliver valuable insights for coastal management, environmental monitoring and scientific research.
2025
Autores
Magalhaes, C; Ribeiro, AI; Rodrigues, R; Meireles, A; Alves, AC; Rocha, J; de Lima, FP; Martins, M; Mitu, B; Satulu, V; Dinescu, G; Padrao, J; Zille, A;
Publicação
APPLIED SURFACE SCIENCE
Abstract
The manufacturing process of thermoregulation products with polyester (PES) fabric and conductive polymers such as poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) with proper wearability, comfort, and high performance is still a challenge due to low adhesion, environment instability and nonuniform coatings. This study presents a simple and effective method for producing thermoregulatory PES fabrics using the Joule heating effect. Textiles treated with dielectric barrier discharge (DBD) plasma were functionalized with PEDOT:PSS incorporating secondary dopants, such as dimethyl sulfoxide (DMSO) and glycerol (GLY). PEDOT:PSS was used because it does not compromise the mechanical properties of base materials. DBD plasma treatment was applied to PES to improve the substrate's functional groups and consequently increase adhesion and homogeneity of the PEDOT:PSS on the substrate. The polymer were applied to the textiles by dip-pad-drycure method ensuring uniform distribution and homogeneous heating of the materials. The samples' conductivity, impedance, potential and Joule effect, and their morphological, chemical and thermal properties were studied. Control samples without plasma treatment and secondary dopants were also prepared. The results showed that the DBD-treated samples, coated with 5 layers of PEDOT:PSS, doped with DMSO 7 % (w/v), displayed the best conductivity and Joule effect performance reaching 44.3 degrees C after 1 h.
2025
Autores
Matos, T; Martins, MS; Faria, CL; Rocha, JL; Gonçalves, LM;
Publicação
2025 7TH EXPERIMENT@ INTERNATIONAL CONFERENCE, EXP.AT'25
Abstract
This work presents the development of low-cost, low-power, and disposable marine monitoring technologies designed to support oceanographic studies in remote and extreme environments. These platforms were initially targeted for underwater volcanic locations but offer a broader application potential for ocean research. Three main technologies were developed and tested: underwater monitoring probes for real-time water quality assessments in geothermal springs, deep-sea probes for vertical ocean profiling and autonomous drift-phase monitoring, and a surface buoy for rapid-response environmental monitoring. Field deployments in diverse locations, including the Ponta da Ferraria (S. Miguel, Azores), Banco D. Joao de Castro (Atlantic Ocean), and the Cumbre Vieja volcanic eruption site (La Palma, Canarias), demonstrated the operational feasibility of these systems. Despite challenges in deep-sea operation and deployment conditions, the results highlight the potential of these platforms for scientific studies, environmental monitoring, and emergency response. Their adaptability and modularity make them valuable tools for a wide range of oceanographic applications beyond their initial focus. Ongoing efforts to improve marine communication reliability, sensor integration, and resilience to extreme ocean conditions hold the potential to further expand the role of these technologies in marine exploration.
2025
Autores
Ferreira, J; Pinto, V; Matos, T; Catarino, S; Minas, G; Sousa, P;
Publicação
Proceedings of the 18th International Joint Conference on Biomedical Engineering Systems and Technologies
Abstract
2025
Autores
Pacheco, FD; Rebelo, PM; Sousa, RB; Silva, MF; Mendonça, HS;
Publicação
2025 IEEE INTERNATIONAL CONFERENCE ON AUTONOMOUS ROBOT SYSTEMS AND COMPETITIONS, ICARSC
Abstract
Radio-Frequency IDentification (RFID) technologies automate the identification of objects and persons, having several applications in retail, manufacturing, and intralogistics sectors. Several works explore the application of RFID systems in robotics and intralogistics, focusing on locating robots, tags, and inventory management. This paper addresses the challenge of intralogistics cargo trolleys communicating their characteristics to an autonomous mobile robot through an RFID system. The robot must know the trolley's relative pose to avoid collisions with the surroundings. As a result, the passive tag on the cargo communicates information to the robot, including the base footprint of the trolley. The proposed RFID system includes the development of a controller board to interact with the frontend integrated circuit of an external antenna onboard the industrial mobile robot. Experimental results assess the system's readability distance in two distinct environments and with two different antenna modules. All the code and documentation are available in a public repository.
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