2025
Authors
Silva, CAM; Bessa, RJ;
Publication
APPLIED ENERGY
Abstract
The electrification of the transport sector is a critical element in the transition to a low-emissions economy, driven by the widespread adoption of electric vehicles (EV) and the integration of renewable energy sources (RES). However, managing the increasing demand for EV charging infrastructure while meeting carbon emission reduction targets is a significant challenge for charging station operators. This work introduces a novel carbon-aware dynamic pricing framework for EV charging, formulated as a chance-constrained optimization problem to consider forecast uncertainties in RES generation, load, and grid carbon intensity. The model generates day-ahead dynamic tariffs for EV drivers with a certain elastic behavior while optimizing costs and complying with a carbon emissions budget. Different types of budgets for Scope 2 emissions (indirect emissions of purchased electricity consumed by a company) are conceptualized and demonstrate the advantages of a stochastic approach over deterministic models in managing emissions under forecast uncertainty, improving the reduction rate of emissions per feasible day of optimization by 24 %. Additionally, a surrogate machine learning model is proposed to approximate the outcomes of stochastic optimization, enabling the application of state-of-the-art explainability techniques to enhance understanding and communication of dynamic pricing decisions under forecast uncertainty. It was found that lower tariffs are explained, for instance, by periods of higher renewable energy availability and lower market prices and that the most important feature was the hour of the day.
2025
Authors
Matos, T; Dinis, H; Faria, CL; Martins, MS;
Publication
APPLIED OCEAN RESEARCH
Abstract
This study presents the development and testing of satellite antennas for the SONDA probe, an innovative deepsea monitoring system designed to be deployed by high-altitude balloons. The probe descends to the deep ocean, resurfaces, and transmits data while functioning as a drifter. The project faced unique design constraints, including the need for low-cost materials and lightweight construction for balloon deployment. These constraints ruled out traditional hermetic housings, necessitating alternative solutions for antenna protection. The work focused on custom ceramic patch antennas and their performance under various protective coatings, which affected the antennas' resonance and gain. Thinner layers effectively protected the antennas from high-pressure conditions and water ingress, maintaining functionality. Experiments on antenna height revealed optimal positioning above the water surface to minimize wave-induced signal interference. Hyperbaric chamber tests validated the mechanical integrity and functionality of the antennas under pressures equivalent to depths of 1500 m Antenna characterization techniques were employed in an anechoic chamber to validate antenna performance with the coating and to assess their correct operation after the hyperbaric tests. Field deployments demonstrated the antennas' capability to transmit data after diving. Challenges included communication delays, corrupted data, and mechanical vulnerabilities in materials. The findings emphasize the importance of rigorous mechanical design, material selection, and system optimization to ensure reliability in marine environments. This work advances the development of low-cost, lightweight, and modular probes for autonomous ocean monitoring, with potential applications in long-term drifter studies, real-time marine monitoring and oceanographic research.
2025
Authors
Leal, F; Veloso, B; Malheiro, B; Burguillo, JC;
Publication
EXPERT SYSTEMS
Abstract
Crowdsourced data streams are popular and extremely valuable in several domains, namely in tourism. Tourism crowdsourcing platforms rely on past tourist and business inputs to provide tailored recommendations to current users in real time. The continuous, open, dynamic and non-curated nature of the crowd-originated data demands specific stream mining techniques to support online profiling, recommendation, change detection and adaptation, explanation and evaluation. The sought techniques must, not only, continuously improve and adapt profiles and models; but must also be transparent, overcome biases, prioritize preferences, master huge data volumes and all in real time. This article surveys the state-of-art of adaptive and explainable stream recommendation, extends the taxonomy of explainable recommendations from the offline to the stream-based scenario, and identifies future research opportunities.
2025
Authors
Simões, C; Coelho, A; Ricardo, M;
Publication
20th Wireless On-Demand Network Systems and Services Conference, WONS 2025, Hintertux, Austria, January 27-29, 2025
Abstract
High-frequency radio networks, including those operating in the millimeter-wave bands, are sensible to Line-of-Sight (LoS) obstructions. Computer Vision (CV) algorithms can be leveraged to improve network performance by processing and interpreting visual data, enabling obstacle avoidance and ensuring LoS signal propagation. We propose a vision-aided Radio Access Network (RAN) based on the O-RAN architecture and capable of perceiving the surrounding environment. The vision-aided RAN consists of a gNodeB (gNB) equipped with a video camera that employs CV techniques to extract critical environmental information. An xApp is used to collect and process metrics from the RAN and receive data from a Vision Module (VM). This enhances the RAN's ability to perceive its surroundings, leading to better connectivity in challenging environments. © 2025 IFIP.
2025
Authors
Campos, TD; Martins, M; Quyen, N; de Moura, MFSF; Dourado, N;
Publication
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
Authors
Shafafi, K; Ricardo, M; Campos, R;
Publication
CoRR
Abstract
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