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Publicações

2025

Depth Control of Variable Buoyancy Systems: A Low Energy Approach Using a VSC with a Variable-Amplitude Law

Autores
Pinto, JB; Carneiro, JF; de Almeida, FG; Cruz, NA;

Publicação
ACTUATORS

Abstract
Underwater exploration relies heavily on autonomous underwater vehicles and sensor platforms for sustained monitoring of marine environments, yet their operational duration is limited by energy constraints. To enhance energy efficiency, various control strategies have been proposed, including robust, optimal, and disturbance-aware approaches. Recent work introduced a variable structure controller (VSC) with a constant-amplitude control action for depth control of a platform equipped with a variable buoyancy module, achieving an average 22% reduction in energy use in comparison with conventional PID-based controllers. In a separate paper, the conditions for its closed-loop stability were proven. This study extends these works by proposing a controller with a variable-amplitude control action designed to minimize energy consumption. A formal proof of stability is provided to guarantee safe operation even under conservative assumptions. The controller is applied to a previously developed depth-regulated sensor platform using a validated physical model. Additionally, this study analyzes how the controller parameters and mission requirements affect stability regions, offering practical guidelines for parameter tuning. A method to estimate oscillation amplitude during hovering tasks is also introduced. Simulation trials validate the proposed approach, showing energy savings of up to 16% when compared to the controller using a constant-amplitude control action.

2025

Optimisation-Based Sensitivity Analysis of PV and Energy Storage Sizing in Commercial Buildings

Autores
Santos, TB; Silva, CS; Bernardo, H;

Publicação
2025 9TH INTERNATIONAL YOUNG ENGINEERS FORUM ON ELECTRICAL AND COMPUTER ENGINEERING, YEF-ECE

Abstract
In recent years, non-residential buildings have increasingly adopted renewable energy generation systems to align with the European Union's goal of achieving carbon neutrality by 2050. However, energy storage systems play a fundamental role in maximising the use of the generated renewable energy. Due to their high acquisition costs, adequately sizing these systems is essential. Moreover, applying an optimal scheduling strategy for energy storage operation can significantly improve the economic viability of such systems by reducing energy-related costs. In this paper, a MILP-based optimisation algorithm-incorporating battery lifespan constraints-is applied to a reference commercial building to schedule the operation of the storage system. A sensitivity analysis on the installed photovoltaic power and energy storage capacity is performed to evaluate their impact on the economic and operational performance of the optimisation algorithm under different sizing configurations.

2025

Development of a Non-Invasive Clinical Machine Learning System for Arterial Pulse Wave Velocity Estimation

Autores
Martinez-Rodrigo, A; Pedrosa, J; Carneiro, D; Cavero-Redondo, I; Saz-Lara, A;

Publicação
APPLIED SCIENCES-BASEL

Abstract
Arterial stiffness (AS) is a well-established predictor of cardiovascular events, including myocardial infarction and stroke. One of the most recognized methods for assessing AS is through arterial pulse wave velocity (aPWV), which provides valuable clinical insights into vascular health. However, its measurement typically requires specialized equipment, making it inaccessible in primary healthcare centers and low-resource settings. In this study, we developed and validated different machine learning models to estimate aPWV using common clinical markers routinely collected in standard medical examinations. Thus, we trained five regression models: Linear Regression, Polynomial Regression (PR), Gradient Boosting Regression, Support Vector Regression, and Neural Networks (NNs) on the EVasCu dataset, a cohort of apparently healthy individuals. A 10-fold cross-validation demonstrated that PR and NN achieved the highest predictive performance, effectively capturing nonlinear relationships in the data. External validation on two independent datasets, VascuNET (a healthy population) and ExIC-FEp (a cohort of cardiopathic patients), confirmed the robustness of PR and NN (R- (2)> 0.90) across different vascular conditions. These results indicate that by using easily accessible clinical variables and AI-driven insights, it is possible to develop a cost-effective tool for aPWV estimation, enabling early cardiovascular risk stratification in underserved and rural areas where specialized AS measurement devices are unavailable.

2025

High-resolution portable bluetooth module for ECG and EMG acquisition

Autores
Luiz, LE; Soares, S; Valente, A; Barroso, J; Leitao, P; Teixeira, JP;

Publicação
COMPUTATIONAL AND STRUCTURAL BIOTECHNOLOGY JOURNAL

Abstract
Problem: Portable ECG/sEMG acquisition systems for telemedicine often lack application flexibility (e.g., limited configurability, signal validation) and efficient wireless data handling. Methodology: A modular biosignal acquisition system with up to 8 channels, 24-bit resolution and configurable sampling (1-4 kHz) is proposed, featuring per-channel gain/source adjustments, internal MUX-based reference drive, and visual electrode integrity monitoring; Bluetooth (R) transmits data via a bit-wise packet structure (83.92% smaller than JSON, 7.28 times faster decoding with linear complexity based on input size). Results: maximum 6.7 mu V-rms input-referred noise; harmonic signal correlations >99.99%, worst-case THD of -53.03 dBc, and pulse wave correlation >99.68% in frequency-domain with maximum NMSE% of 6e-6%; and 22.3-hour operation (3.3 Ah battery @ 150 mA). Conclusion: The system enables high-fidelity, power-efficient acquisition with validated signal integrity and adaptable multi-channel acquisition, addressing gaps in portable biosensing.

2025

Good Practices for Improving Gender Balance and Diversity Throughout an Academic Career

Autores
Murphy, B; Lopes, CT; Merelli, E; Diaconu, MG; Gallais, M; Diaz, P; Silva, PA; Mavrikiou, P; Ghilezan, S; Kremer, S;

Publicação
Actions for Gender Balance in Informatics Across Europe

Abstract
Women are seriously underrepresented in Informatics and STEM areas in general. In this chapter, we raise awareness around some of the key issues and problems that women and other minority groups may face and identify good practices to improve gender balance—and diversity in general—in academia. Our goal is to cover the entire academic career: we start with the recruitment and application evaluation, discuss retainment of female talent, including work life balance, as well as promotion, including strategies to battle the glass ceiling and sticky floor phenomena. In each section, we also provide examples of actions that have been deployed. © 2025 The Editor(s) (if applicable) and The Author(s).

2025

Is school lunch participation associated with higher adherence to the Mediterranean Diet and healthier body weight? – a cross-sectional analysis of baseline data from the R23 project

Autores
Espanhol, R; Jacinto Soares, C; MPM Oliveira, B; Torres, D; João Gregório, M;

Publicação
Acta Portuguesa de Nutrição

Abstract
Introduction: School lunches are essential in promoting a sustainable, healthy diet for children. However, students’ adherence in developed countries is modest. Objectives: A cross-sectional study with the objective of evaluating school lunch participation and exploring the factors influencing participation and its associations with sociodemographic characteristics, socioeconomic status, body weight, and adherence to the Mediterranean Dietary Pattern. Methodology: Baseline results from the R23 project, collected during the first five weeks of the 2022/23 school year, were used. In total, 806 students, aged 10–16 years, from the 2nd and 3rd cycles of basic education in Portugal, Benavente, participated in this study. Using a face-to-face structured questionnaire, students’ sociodemographic data, socioeconomic status, adherence to the Mediterranean Dietary Pattern, and school lunch participation were assessed. Daily school lunch participation was obtained via the school lunch booking service. Anthropometric measurements (weight, height and waist circumference) were performed on all students with signed consent forms. Results: The school lunch participation rate was 25.3%. Overall, 39.1% of students reported never attending the school canteen. Only 27% of the students eligible for Free or Reduced-Price Meals had an effective adherence to school lunch, and the non-participation rate in this group was 31%. Key barriers included living near to school and dissatisfaction with meal quality. Students' school lunch participation was significantly associated with age, grade, eligibility for Free or Reduced-Price Meals, and adherence to Mediterranean Dietary Pattern. Younger students and students eligible for Free or Reduced-Price Meals went to the canteen more often. While school lunch participation was positively and significantly associated with higher adherence to Mediterranean Dietary Pattern, no significant relationship was observed with body mass index or waist-to-height ratio. Students with greater adherence to Mediterranean Dietary Pattern displayed healthier body mass index and waist-to-height ratio. Conclusions: School lunch participation among adolescents was low, but increased participation was associated with higher adherence to the Mediterranean Dietary Pattern. These findings highlight the importance of school lunches in promoting healthier eating habits.

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