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Publications

2025

A Distributed IoT System for Real-Time Sports Performance Analysis in Physical Education

Authors
Rodrigues, NB; Ramos, RJ; Castro, M; Jesus, N; Guedes, P; Ferreira, MS; Silva, R; Oliveira, L;

Publication
icSPORTS

Abstract
Integrating Internet of Things (IoT) technologies into physical education (PE) presents opportunities for improving the methodologies for collecting, analysing, and managing student performance data. However, it also introduces technical challenges, particularly related to the real-time handling and protection of sensitive data in dynamic training environments. This paper presents a comprehensive solution outline based on a private local network architecture that supports scalable sensor data processing, real-time database integration, and mobile application interfaces. The proposed distributed system ensures data integrity, low-latency communication, and secure access while enabling educators to monitor student performance in real-time and review historical data. The system supports more personalised, data-driven training strategies by providing actionable insights for sports education.

2025

Simulating Biases for Interpretable Fairness in Offline and Online Classifiers

Authors
Inácio, R; Kokkinogenis, Z; Cerqueira, V; Soares, C;

Publication
CoRR

Abstract
Predictive models often reinforce biases which were originally embedded in their training data, through skewed decisions. In such cases, mitigation methods are critical to ensure that, regardless of the prevailing disparities, model outcomes are adjusted to be fair. To assess this, datasets could be systematically generated with specific biases, to train machine learning classifiers. Then, predictive outcomes could aid in the understanding of this bias embedding process. Hence, an agent-based model (ABM), depicting a loan application process that represents various systemic biases across two demographic groups, was developed to produce synthetic datasets. Then, by applying classifiers trained on them to predict loan outcomes, we can assess how biased data leads to unfairness. This highlights a main contribution of this work: a framework for synthetic dataset generation with controllable bias injection. We also contribute with a novel explainability technique, which shows how mitigations affect the way classifiers leverage data features, via second-order Shapley values. In experiments, both offline and online learning approaches are employed. Mitigations are applied at different stages of the modelling pipeline, such as during pre-processing and in-processing.

2025

Histopathological Imaging Dataset for Oral Cancer Analysis: A Study with a Data Leakage Warning

Authors
Nogueira, DM; Gomes, EF;

Publication
BIOSTEC (1)

Abstract

2025

Contract Usage and Evolution in Android Mobile Applications

Authors
Ferreira, DR; Mendes, A; Ferreira, JF; Carreira, C;

Publication
39TH EUROPEAN CONFERENCE ON OBJECT-ORIENTED PROGRAMMING, ECOOP 2025

Abstract
Contracts and assertions are effective methods to enhance software quality by enforcing preconditions, postconditions, and invariants. Previous research has demonstrated the value of contracts in traditional software development. However, the adoption and impact of contracts in the context of mobile app development, particularly of Android apps, remain unexplored. To address this, we present the first large-scale empirical study on the use of contracts in Android apps, written in Java or Kotlin. We consider contract elements divided into five categories: conditional runtime exceptions, APIs, annotations, assertions, and other. We analyzed 2,390 Android apps from the F-Droid repository and processed 52,977 KLOC to determine 1) how and to what extent contracts are used, 2) which language features are used to denote contracts, 3) how contract usage evolves from the first to the last version, and 4) whether contracts are used safely in the context of program evolution and inheritance. Our findings include: 1) although most apps do not specify contracts, annotation-based approaches are the most popular; 2) apps that use contracts continue to use them in later versions, but the number of methods increases at a higher rate than the number of contracts; and 3) there are potentially unsafe specification changes when apps evolve and in subtyping relationships, which indicates a lack of specification stability. Finally, we present a qualitative study that gathers challenges faced by practitioners when using contracts and that validates our recommendations.

2025

Toward AI-Native 6G: Unveiling Online Optimization and Deep Reinforcement Learning for Autonomous Network Slicing

Authors
Abo-eleneen, A; Helmy, M; Abdellatif, AA; Abdallah, M; Mohamed, A; Erbad, A;

Publication
IEEE INTERNET OF THINGS MAGAZINE

Abstract
The shift to AI-native 6G networks demands autonomous slicing strategies that can adapt to diverse and evolving edge and IoT service needs. Two paradigms have emerged: Learn to Slice (L2S), where AI optimizes network slicing for general services, and Slice to Learn (S2L), where slices support AI model training, often offloaded from Internet of Things (IoT) devices. Existing S2L approaches typically optimize communication or computation in isolation. This paper presents the first unified framework that jointly optimizes communication resources, computation capacity, and AI hyperparameters to maximize the average accuracy of multiple concurrent AI services. We address the complexity of this joint problem by applying L2S-inspired techniques to enhance S2L, introducing two autonomous agents: EXP3 from online convex optimization and DQN from deep reinforcement learning. Extensive experiments demonstrate and contrast the effectiveness of these agents in maximizing aggregated AI accuracy, supporting knowledge transfer, and sustaining robust performance under adversarial and long-term conditions, thereby enhancing the realization of zero-touch network management for AI services in 6G networks, supporting resource-constrained IoT.

2025

A Review on Distributed Voltage Regulators for High-Performance Integrated Circuits

Authors
Oliveira, G; Duarte, C; Santos, MB; Pina, M;

Publication
U.Porto Journal of Engineering

Abstract
Conventional power distribution networks (PDNs), in which individual voltage regulators power the entire integrated circuit (IC), are ineffective for high-power, large-area ICs. In highperformance systems-on-chip (SoCs) and microprocessors (in particular those designed for AI applications), shrinking technology nodes are leading to higher current densities, which impose thermal constraints and limit the portion of the chip that can be simultaneously powered (“dark silicon”). PDNs with point-of-load regulation offer a promising alternative. The distributed nature of their design inherently relaxes thermal constraints while minimizing high-current routing overhead (IR drops), thereby improving the PDN efficiency. In this work, the concept of on-chip distributed voltage regulation is introduced. Previously reported distributed voltage regulator designs are reviewed, emphasizing their major achievements and limitations. Then, the challenges that hinder a more ubiquitous adoption of such designs, namely stability (analysis) and unbalanced load sharing, are discussed. Existing solutions addressing these challenges are also presented. Finally, a comparative analysis of the performance of these regulators is presented, and insights into the future direction of distributed voltage regulation are offered. © (2025), (Universidade do Porto - Faculdade de Engenharia). All rights reserved.

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