Abstract
Underwater wireless communications face significant challenges due to propagation constraints, limiting the effectiveness of traditional radio and optical technologies. Long-range acoustic communications support distances up to a few kilometers, but suffer from low bandwidth, high error ratios, and multipath interference. Semantic communications, which focus on transmitting extracted semantic features rather than raw data, present a promising solution by significantly reducing the volume of data transmitted over the wireless link. This paper evaluates the resilience of SAGE, a semantic-oriented communications framework that combines semantic processing with Generative Artificial Intelligence (GenAI) to compress and transmit image data as textual descriptions over acoustic links. To assess robustness, we use a custom-tailored simulator that introduces character errors observed in underwater acoustic channels. Evaluation results show that SAGE can successfully reconstruct meaningful image content even under varying error conditions, highlighting its potential for robust and efficient underwater wireless communication in harsh environments.

Abstract
Robotic competitions have been popularly applied in the educational context, proving to be an excellent method for fostering student engagement and interest in science, technology, engineering, and math (STEM). In this context, this paper presents the application of mobile robots in a classroom competition, in order to encourage students to enhance mobile robotics concepts learning in a dynamic and collaborative environment. The mobile robot prototyping is presented, and the methodology, including the Hardware-in-the-loop approach applied in the classrooms, is also described, together with the competition rules and challenges proposed for the students. The results indicated an improvement in students’ motivation, teamwork, communication, and the development of technical skills, computational thinking, and problem-solving.

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Abstract

Depressive symptoms are common among older adults and can significantly impact their quality of life. Yet, many older adults face barriers to accessing psychological treatment. Internet-based cognitive behavioural therapy (iCBT) is a promising alternative to face-to-face treatments, but its feasibility among older adults is less researched.

Abstract
This study proposes a virtual reality (VR) experience that aims at raising awareness toward climate change through the simulation of a wildfire, a natural disaster that is becoming increasingly frequent in Portugal, and promote the adoption of sustainable behaviours and mitigation strategies. Here, the feasibility of such an approach is tested implementing both subjective, with the Igroup Presence Questionnaire (IPQ) to evaluate the senses of presence, involvement and realism, and objective measures, i.e., a set of features extracted from the in-VR movement trajectories. The mean scores of IPQ items demonstrated that such devastating event is particularly effective in enhancing participants' involvement and sense of presence within the virtual environment, reinforcing the potential of VR to foster pro-environmental attitudes. Results also highlighted that these feelings were not altered by VR familiarity, whereas presence ratings were higher for participants who visited the actual location that the virtual environment replicated. Correlation analysis also discovered significant relationships between subjective and objective parameters. © 2025 IEEE.

Abstract
Volatility in energy prices, alongside the European Commission's decarbonization strategy, has led to reforming the European electricity market and the creation of a hydrogen strategy. Hydrogen and electricity have a symbiotic relationship: hydrogen production through electrolysis relies on electricity, while its production provides flexibility to the power system utilizing renewable energy surpluses. This research provides a joint electricity and hydrogen market model based on Cournot equilibrium, solved with an equivalent optimization problem, incorporating contracts for both goods. Results for the MIBEL show that contracts increase market competition, reduce prices, and enhance renewable energy utilization. Wholesale electricity and hydrogen prices decrease by 10 % and 8 %, respectively, while electrolytic hydrogen production rises by 10 %. Profits increase by over 20 %, with the hydrogen sector doubling its gains. The model also identifies contract prices that ensure profitability and emissions reduction. These findings highlight the potential of PPAs and HPAs to support energy transition goals.