2025
Autores
Elsaid, M; Finich, S; Salgado, HM; Pessoa, LM;
Publicação
2025 19TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP
Abstract
Research on Programmable Electromagnetic Surfaces has gained considerable attention as an enabling technology for 6G communications, particularly at millimeter-wave and sub-THz bands. However, RISs face challenges related to the need for high-performance reconfigurable techniques that offer compact size and reduced power consumption at high frequencies. Moreover, the experimental characterization of unit cell performance using a waveguide remains a challenging issue. This paper discusses the design and performance analysis of a 1-bit reconfigurable unit cell at the Dband using non-volatile reconfigurable technology. The efficiency analysis of the unit cell was performed using periodic boundary conditions and waveguide configurations to mitigate simulation risks and validate the proposed design at the unit cell level. All simulation configurations confirmed an operational bandwidth of 25.65 GHz across the 147.8-173.45 GHz range, with a reflection loss of less than 1 dB and a phase difference within 180 degrees +/- 20 degrees.
2025
Autores
Habib H.U.R.; Reiz C.; Alves E.; Gouveia C.S.;
Publicação
2025 IEEE Kiel Powertech Powertech 2025
Abstract
This paper presents an adaptive protection strategy for multi-microgrid (MMG) systems with inverter-based resources (IBRs) in medium voltage (MV) networks, using the IEEE 33-bus test system. The approach combines overcurrent (OC) and undervoltage (UV) protections through an offline-optimized, clustering-based scheme and real-time selection of setting groups. A metaheuristic algorithm determines optimal relay settings for representative scenarios, ensuring responsive and coordinated protection. Hardware-in-the-loop validation on OPAL-RT confirms the method's effectiveness across varying loads, DER outputs, and fault conditions. Results demonstrate reliable fault isolation, smooth mode transitions, and uninterrupted supply to healthy segments. Identified limitations in high-impedance fault handling suggest future improvements.
2025
Autores
Guimarães, M; Carneiro, D; Soares, L; Ribeiro, M; Loureiro, G;
Publicação
Advances in Information and Communication - Proceedings of the 2025 Future of Information and Communication Conference (FICC), Volume 1, Berlin, Germany, 27-28 April 2025.
Abstract
The interaction between humans and technology has always been a key determinant factor of adoption and efficiency. This is true whether the interaction is with hardware, software or data. In the particular case of Information Retrieval (IR), recent developments in Deep Learning and Natural Language Processing (NLP) techniques opened the door to more natural and efficient IR means, no longer based on keywords or similarity metrics but on a distributed representation of meaning. In this paper we propose an agent-based architecture to serve as an interface with industrial systems, in which agents are powered by specific Large Language Models (LLMs). Its main goal is to make the interaction with such systems (e.g. data sources, production systems, machines) natural, allowing users to execute complex tasks with simple prompts. To this end, key aspects considered in the architecture are human-centricity and context-awareness. This paper provides a high-level description of this architecture, and then focuses on the development and evaluation of one of its key agents, responsible for information retrieval. For this purpose, we detail three application scenarios, and evaluate the ability of this agent to select the appropriate data sources to answer a specific prompt. Depending on the scenario and on the underlying model, results show an accuracy of up to 80%, showing that the proposed agent can be used to autonomously select from among several available data sources to answer a specific information need. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.
2025
Autores
Benhanifia, A; Ben Cheikh, Z; Oliveira, PM; Valente, A; Lima, J;
Publicação
INTELLIGENT SYSTEMS WITH APPLICATIONS
Abstract
Predictive maintenance (PDM) is emerging as a strong transformative tool within Industry 4.0, enabling significant improvements in the sustainability and efficiency of manufacturing processes. This in-depth literature review, which follows the PRISMA 2020 framework, examines how PDM is being implemented in several areas of the manufacturing industry, focusing on how it is taking advantage of technological advances such as artificial intelligence (AI) and the Internet of Things (IoT). The presented in-depth evaluation of the technological principles, implementation methods, economic consequences, and operational improvements based on academic and industrial sources and new innovations is performed. According to the studies, integrating CDM can significantly increase machine uptime and reliability while reducing maintenance costs. In addition, the transition to PDM systems that use real-time data to predict faults and plan maintenance more accurately holds out promising prospects. However, there are still gaps in the overall methodologies for measuring the return on investment of PDM implementations, suggesting an essential research direction.
2025
Autores
Alves, LJF; Diehl, CA; Schlemmer, E; Lima, DMLF; Boose, ESdS;
Publicação
TICs & EaD em Foco
Abstract
2025
Autores
Pinto, R; Matos, T; Mendes, D; Rodrigues, R;
Publicação
VRST
Abstract
Virtual Reality applications increasingly require methods to effectively guide users to important elements within the virtual environment. Central visual cues are the most common method, which have proven effective for directing attention, yet often compromise on level of immersion. This work explored whether peripheral visual cues could serve as an alternative approach that supports attention guidance while preserving sense of presence. We performed a user study with 24 participants to compare four visual cues: two central cues (Floating Text and Floating Arrow) and two peripheral cues (Edge Lighting and Swarm). Users completed a visual search task of 7 objects for each visual cue, with data collected on performance through reaction time, round time, and total errors. Additionally, presence and workload were evaluated through the IGROUP Presence Questionnaire and NASA Task Load Index, respectively. No statistically significant differences were found between peripheral and central cues for presence, however performance and workload varied significantly based on specific cue implementation rather than type of positioning. Our findings indicate that peripheral positioning does not inherently provide attention guidance advantages over central placement. Instead, thoughtful cue design, with a simple yet clear appearance and behavior appears to be the critical factor for achieving effective attention guidance while preserving presence in IVEs. These results provide valuable insights for VR content creators to facilitate the design process of VR experiences. © 2025 Copyright held by the owner/author(s).
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