ESTiG - Artigos em Revistas Indexados à WoS/Scopus
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- A 2.4-GHz low-power/low-voltage wireless plug-and-play module for EEG applicationsPublication . Carmo, João Paulo; Dias, Nuno; Silva, Hélder; Mendes, P.M.; Couto, Carlos; Correia, José H.This paper presents a plug-and-play module for wireless electroencephalogram (EEG) applications. The wireless module is composed by an electrode, processing electronics, a radio-frequency (RF) transceiver, and an associated antenna. The RF transceiver was fabricated in the UMC RF 0.18 mum CMOS process, and operates in the 2.4-GHz ISM band. The receiver has a sensitivity of -60 dBm and a power consumption of 6.3 mW from a 1.8 V supply. The transmitter delivers an output power of 0 dBm with a power consumption of 11.2 mW, for a range of 10 m. It is also presented the electrical performance and comparison between different electrodes for EEG applications, namely sputtered titanium nitride (TiN) electrodes, standard sintered silver/silver chloride (Ag/AgCl) ring electrodes and sputtered iridium oxide (IrO2) electrodes. The experimental results show a better performance of the sputtered IrO2 electrodes compared with the standard sintered Ag/AgCl ring electrodes. These results promise a new opportunity for the application of a dry IrO2 electrodes in wireless modules for using in a wearable EEG braincap. These wireless EEG modules will allow patients to wear a brain cap and maintain their mobility, while simultaneously having their electrical brain activity monitored.
- 2024 U.S. presidential elections: An event study for U.S. and non-U.S. fossil fuel and renewable listed firmsPublication . Martins, António Miguel; Albuquerque, Bruno; Sardinha, Luís; Moutinho, NunoThis study examines the short-term market effect of Donald Trump' victory in the 2024 US presidential election on largest US and non-US listed worldwide fuel fossil and renewable firms. Employing an event study methodology, we observe a negative and statistically significant stock price reaction for worldwide renewable listed firms. An analysis by economic zones reveals the existence of negative abnormal returns for renewable energy firms in the US, Europe, India and in the rest of the world. In the case of China, abnormal returns are not statistically significant. With respect to worldwide fossil fuel listed firms, abnormal returns are generally not statistically significant. However, regarding US firms, we observe positive and statistically significant abnormal returns. These abnormal returns are explained by the change of US energy policy (pro-oil and gas policy) and the expected cut in subsidies and lower profitability of investments in green energies. Finally, our study provide insight into which firm-specific characteristics emerge as value drives around US presidential elections. The results show that despite the change in environmental policy in the US, favourable to fossil energy, the stock markets reward firms with high environmental ratings. Overall, our results indicate that 2024 US presidential election, for implying a change in US energy policy, has relevant policy implications for energy listed firms.
- 3D numerical modeling of geosynthetics for soil reinforcement: a bibliometric analysis and literature reviewPublication . Paiva, Lucas; Pinho-Lopes, Margarida; Paula, António Miguel; Valente, RoberttSoil reinforcement using geosynthetics is an efficient and cost-effective solution for a variety of geotechnical structures. Along with the increasing use of geosynthetics, there is a need to expand and enhance the design methodologies for these elements, which are still frequently based on conservative limit equilibrium approaches. In this paper, a bibliometric analysis was conducted on geosynthetic-reinforced soil structures (GRS), identifying the state of the art, research trends, and other indicators. The data were obtained from the Scopus platform and processed by VOSViewer v1.6 software. The initial search comprised 552 papers and the screening process selected 516 relevant papers from 1992 to October 2023. The study analyzed the occurrence of publications by year, keyword trends, authors, citations/co-citations, and bibliographic coupling. Then, a focus was given to 3D modeling research on geosynthetics, highlighting the dominant modeling techniques, material properties, and design challenges in GRS. The bibliometric analysis provided a crucial guideline in the identification of relevant papers and research trends, and a series of conclusions were presented regarding the 3D modeling techniques, choice of material properties, and boundary conditions.
- 5.7 GHz on-chip antenna/RF CMOS transceiver for wireless sensor networkSPublication . Carmo, João Paulo; Mendes, P.M.; Couto, Carlos; Correia, José H.This paper describes a chip-size antenna for operation at 5.7 GHz, assembled with a low-power, low-voltage RF CMOS transceiver, fabricated in UMC RF CMOS 0.18 μm process. Measurements shown a patch antenna with the central frequency of 5.705 GHz, a bandwidth of 90 MHz at −10 dB of return loss, a directive gain of 0.3 dB, with an efficiency of 18%, and a transceiver with a measured total power consumption of 23 mW. This microsystem is intended for the use in each wireless node of a wireless sensor network mounted in a wireless electronic shirt, that monitors the cardio-respiratory function and posture.
- A 70-Year industrial electronics society evolution through industrial revolutions: the rise and flourishing of information and communication technologiesPublication . Colombo, Armando W.; Karnouskos, Stamatis; Yu, Xinghuo; Kaynak, Okyay; Luo, Ren C.; Shi, Yang; Leitão, Paulo; Ribeiro, Luis; Haase, JanThe Industrial Revolution, which originally involved the change from an agrarian and handicraft economy to a market dominated by factory mechanization during the early 18th century, has profoundly shaped the world. It has progressed through four disruptive phases: Industry 1.0 through Industry 4.0. Industry 1.0 encompassed early automation, while Industry 2.0 began at the end of the 19th century, when enormous technological advances were made, such as mass production, electrification, and new modes of transportation. Industry 3.0 began during the 1970s, a decade that gave rise to the electronics, telecommunications, and computing that enable full automation and robotics. Industry 4.0 kicked off at the dawn of the third millennium, marked by the ubiquitous use of Internet technologies, which have radically transformed how people, society, and industry interact. The inception of the IEEE Industrial Electronics Society (IES) was in 1951 [1], when Industry 2.0 was at its peak and members of the Institute of Radio Engineers Industrial Electronics Group saw the changing technological landscape in electronics. Those IES pioneers established the Society to promote “industrial electronics,” which are defined by Cambridge Dictionary as electronic equipment for industrial purposes. This early vision lives on and is even more relevant today, as industry and society expect technological advances to be relevant and impactful.
- Accessibility strategies to promote inclusive mobility through multi-objective approachPublication . Silva, Tânia; Verde, David; Paiva, Sara; Barreto, Luis; Pereira, Ana I.In recent decades, urban mobility has assumed a need for adaptation due to the more significant congestion experienced in cities and the growing focus on sustainability. Several solutions are proposed to help citizens move around in an urban environment. Most are not yet aware of the universal and accessible aspect that these solutions must have. This paper proposes a route support system embedded in a mobile application, Viana+Acessivel, using a multi-objective approach. The application aims to promote accessible mobility within the city, contributing to physical and psychological well-being for citizens with reduced mobility, temporary or permanently, such as people with spectrum autism disorder, the visually impaired, wheelchair users, pregnant, and the elderly. For the evaluation of the algorithms, four objective measures were considered: accessibility, slope, time, and length of the paths. The tests carried out with different routing algorithms showed that the A-Star presented the fastest results in terms of execution time compared to the Dijkstra, Floyd-Warshall, and Bellman-Ford. When analysing in a multi-objective approach, time, slope and accessibility were demonstrated to be conflicting objectives. Bi-objective and tri-objective were applied and Pareto front was explored.
- Accessible power for medical equipment in remote healthcare: a solution for single-phase power generation using three-phase induction machinesPublication . Romeiro, Bruno; Oliveira, Carlos; Hildenberg, Cicero; Ferreira, Ângela P.; Filho, FranciscoThis work was motivated by the urgent need for reliable electricity in remote areas where conventional power distribution, and consequently access to healthcare, remains impractical. The proposed system is a practical alternative to conventional synchronous generators commonly used in off-grid applications, which have high implementation and maintenance costs and potential risks in healthcare applications due to the spark generated by the brushes. We propose the use of a self-excited single-phase generator, derived from a three-phase induction machine, as a robust, low-cost, highly reliable and safe solution for supplying electrical power to medical applications in remote locations. The work presents a mathematical model based on the theory of symmetrical components, which incorporates frequency variation and unbalanced system operation, along with an analytical methodology to determine the capacitance values required for this application and all system elements, including the definition of the sizing factors KE and KM. The proposed approach allows for rigorous design without relying on empirical procedures as commonly presented in the literature, and is experimentally validated using real medical loads. Our experimental setup incorporates current medical devices, including three infusion pumps, a cardioverter-defibrillator, and a patient monitoring device. Despite modest voltage imbalances observed during steady-state operation, all medical devices maintained adequate functionality during testing. The transient response during load switching showed damped oscillations before returning to steady-state operation, demonstrating stable voltage and frequency behavior without the use of active electronic control. The generator demonstrated satisfactory voltage regulation and short-circuit self-protection capabilities without the need for complex systems, making it economically viable for deployment in resource-constrained environments. These results suggest that the proposed configuration offers a practical solution for the electrification of medical facilities in regions where grid extension remains challenging or prohibitively expensive.
- Accuracy of 2D numerical models towards the prediction of the fire resistance on LSF partition wallsPublication . Piloto, P.A.G.; Gomes, Stephan; Torres, Leonardo; Couto, Carlos; Real, Paulo VilaLightweight steel framing (LSF) walls are commonly used in modern buildings due to their high strength-to -weight ratio and readiness for installation. However, empty cavities within these walls can pose a fire risk if not properly addressed. In order to ensure the fire resistance and performance of LSF walls with empty cavities, various modelling techniques can be employed. Two-dimensional thermal models can also be used to simulate the behaviour of LSF walls with empty cavities in a fire scenario. These models can predict the spread of heat through the empty cavity, allowing designers to identify potential fire hazards and make adjustments to the design to mitigate those risks.Three different computational solution methods were used to compare the fire performance of LSF walls with void cavities. Solution method 1 considers the air-structure interaction in the cavity region. Solution method 2 considers the existence of interface elements for the radiation heat transfer in the cavity region allowing the cavity temperature prediction. Solution method 3 considers the convection and radiation in the cavity region with a prescribed cavity temperature from experiments (hybrid). Solution methods 1 and 3 give a small root mean square error (RMSE), when compared with solution method 2. Solution method 3 gives a better approx-imation because can capture the main fire events during the fire, such as the cracks and fall off. Based on the parametric study, a new proposal is presented to predict the fire resistance by insulation, depending on the gypsum type and thickness.
- Actively detecting multiscale flooding attacks & attack volumes in resource-constrained ICPSPublication . Zahid, Farzana; Kuo, Matthew M.Y.; Sinha, Roopak; Funchal, Gustavo Silva; Pedrosa, Tiago; Leitão, PauloThe significant growth in modern communication technologies has led to an increase in zero-day vulnerabilities that degrade the performance of cyber-physical systems (ICPS). Distributed denial of service (DDoS) attacks are one such threat that overwhelms a target with floods of packets, posing a severe risk to the normal operations of the ICPS. Current solutions to detect DDoS attacks are unsuitable for resource-constrained ICPS. This study proposes actively detecting multiscale flooding DDoS attacks in resource-constrained ICPS by analyzing network traffic in the frequency domain. A two-phased technique detects attack presence and attack volume. Both phases use a novel combination of light-weight and theoretically sound statistical methods. The effectiveness of the proposed technique is evaluated using mainstream metrics like true and false positive rates, accuracy, and precision using BOUN DDoS 2020 and CICDDoS 2019 datasets. An implementation of the proposed approach on a programmable logic controllers-based ICPS demonstrated improvements in resource usage and detection time compared to the existing state-of-the-art.
- ADACOR, a collaborative production automation and control architecturePublication . Leitão, Paulo; Colombo, Armando W.; Restivo, FranciscoAn analysis of the ADACOR collaborative manufacturing control architecture from the point of view of the Collaborative Manufacturing Management paradigm shows how ADACOR supports integration and extension across the manufacturing value chain.