Home collection (FCT)
URI permanente para esta coleção:
Navegar
Entradas recentes
- Drones como ferramenta complementar na segurança de barragens de aterroPublication . Leite, Daniel; Marcelino, João; Guerra, Nuno; Manso, João; Faculdade de Ciências e Tecnologia (FCT); Sociedade Portuguesa de Geotecnia | Imprensa da Universidade de CoimbraEmbankment dams are vital structures for society; however, their operation may involve significant risks. Traditional monitoring methods are fundamental for dam safety, yet they may present operational limitations, such as blind spots, obsolete systems, and inoperative equipment. This work proposes a complementary methodology based on drones to support the early detection of anomalies in these structures. It provides technical guidelines for optimised flight planning and photogrammetric processing using open-source software (WebODM). It also introduces the GCP Finder tool for automating the georeferencing of control points. The case study of the Lapa Dam demonstrates the ability to detect anomalies with sub-centimetre resolution, enabling the quantification of deformations of 15–20 mm on the crest. The results confirm the potential of drones as an emerging tool for dam safety, offering comprehensive coverage at low cost.
- 3D-Printed Serial Snap-Through Architectures for Programmable Mechanical ResponsePublication . A. Santos, Filipe; CERIS - Polo NOVA; Faculdade de Ciências e Tecnologia (FCT); John Wiley & Sons, Ltd.Snap-through instabilities enable sharp, reversible transitions and high energy-storage capacity, making them attractive for mechanical elements with tailored behavior. This work demonstrates the experimental realization of a serial snap-through system composed of monolithic, 3D-printed von Mises truss (VMT) units. The study examines how a small number of bistable elements, arranged in series, can function as a compact mechanical member with a controlled multistage response. Each unit is printed in a single operation with self-releasing hinges ensuring coaxial alignment, and incorporates a sliding support that may be locked or released to tune boundary stiffness and post-snap behavior. Chains of two to four VMTs display programmable responses with transitions and re-hardening stages governed by geometry, engagement gaps, and support constraints. A compact inverted-compliance model rationalizes these observations and extends them to cascades of arbitrary length. Expressing each unit through its nonlinear compliance δ(F) allows the model to recover measured behaviors and support analytical design of target sequences of elastic instabilities. The combination of an experimentally accessible serial architecture and a predictive model provides a practical route for achieving tailored responses in applications requiring staged energy absorption, force limitation, or controlled re-hardening. Serial snap-through composition offers a fabrication-friendly strategy for programmable multistage behavior.
- Hybrid Energy Storage System for BEV and FCEV Charging Stations—Use Case for Aluminum as Energy CarrierPublication . Musicco, Nicola; Ersoy, Hüseyin; Barelli, Linda; Baumann, Manuel; Passerini, Stefano; DCEA - Departamento de Ciências e Engenharia do Ambiente; Faculdade de Ciências e Tecnologia (FCT)The development of electric vehicle (EV) charging infrastructure and load management remains a significant challenge in the transition to sustainable mobility. This chapter explores the use of aluminum (Al) as an energy carrier to enable a hybrid management of BEV charging and fuel cell electric vehicle (FCEV) hydrogen (H2) refueling. The use of aluminum enables on-site power and flexible H2 generation, enhancing flexibility and versatility in EV charge management strategies. The study introduces this emerging concept, providing a theoretical foundation for its techno-economic implications and presenting a formulated use case that examines the potential of the Al wet-combustion process for large hybrid charging stations. By leveraging aluminum’s high energy density, recyclability, and multi-functionality, this approach offers a promising pathway to improve charging infrastructure resilience and energy efficiency.
- An application of logistic regression model to the study of constitutional imbalances in human chromosomal fragile sitesPublication . Silva, Giovani L.; Sequeira, Inês J.; Gomes, D. Prata; Rueff, José; Brás, Aldina; CMA - Centro de Matemática e Aplicações; DM - Departamento de Matemática; Faculdade de Ciências e Tecnologia (FCT); Centre for Toxicogenomics and Human Health (ToxOmics); NOVA Medical School|Faculdade de Ciências Médicas (NMS|FCM); Taylor & FrancisChromosomal fragile sites (CFSs) are loci or regions susceptible to spontaneous or induced occurrence of breaks and rearrangements. They are classified in two main categories, rare and common, depending on their frequency in the population. In order to identify which CFSs are influential or significant in the occurrence of deletions and duplications (chromosomal constitutional imbalances), we propose a logistic regression analysis for the CFS data set, since the underlying response variable is categorical, specifically binary (deletion or duplication). Some results are presented here as an informative preliminary contribution to understand the frailty of these CFS in increasing/decreasing of the deletion odds. This study has implications for our comprehension of human pathogenesis.
- Efficient Pavement Crack Monitoring for Road Life Cycle ManagementPublication . Pena, Raquel; Marques, Nuno C.; Batista, Fátima A.; Manso, João; Marcelino, João; NOVALincsRoad pavements are vital for transportation infrastructure, yet they deteriorate over time due to traffic loads and environmental factors, resulting in cracks and damage. This paper introduces an innovative method for crack detection on road pavements using digital imagery. Our approach incorporates geo-localization, annotates, characterizes, and quantifies crack severity. This empowers experts to monitor crack progression, a critical element in pavement management. The methodology allows for seamless result comparison and augments existing techniques, aiding in condition assessment and conservation strategy determination. Timely detection of cracks enables proactive maintenance, preventing structural degradation, and ensuring user safety and comfort. Leveraging deep learning and open-source frameworks like TensorFlow and QGIS, our approach automates road pavement image analysis and crack identification, providing a cost-effective, accessible solution for crack detection. This research offers significant advantages in resource efficiency and accessibility, especially in areas without regular manual inspections or dedicated vehicles, thereby enhancing road pavement monitoring and maintenance.
- Colorimetric and fluorometric Seleno-BODIPY sensor for selective palladium detection in solution and on a cotton swab platformPublication . Cugnasca, Beatriz S.; Guimarães, Ana Beatriz R.; Dantas, César A. G.; Ribeiro, Francisco W. M.; Hornink, Milene; Cuccovia, Iolanda M.; Stefani, Hélio A.; Braga, Ataualpa A. C.; Correra, Thiago C.; Lodeiro, Carlos; Dos Santos, Alcindo A.; DQ - Departamento de Química; LAQV@REQUIMTE; ElsevierThe fluorescent sensor based on Seleno-BODIPY (BDP-Se) was explored for the detection of palladium in samples of industrial and environmental interest. Colorimetric and fluorometric analyses were conducted, and the sensor demonstrated high selectivity for Pd2+ relative to 21 other cations, as well as high sensitivity (LOD = 0.31 μmol/L by fluorescence) in a turn-on fluorescence process. Quantification of Pd2+ in aliquots from palladium-catalyzed coupling reaction media yielded satisfactory recovery values (up to 87 %). This demonstrates the sensor's applicability and good accuracy for Pd2+ detection in industrial organic environments, avoiding the need for sophisticated sample preparation methods. The structures of the products obtained from the reaction of BDP-Se with PdCl2 (BDP-Se/PdCl2) or PdBr2 (BDP-Se/PdBr2) were characterized by mass analysis, confirming the insertion of the “PdCl” or “PdBr” fragment, respectively, into the BODIPY structure via oxidative addition. Theoretical DFT calculations were performed to demonstrate the stability of the proposed structure, and the theoretical absorption spectrum corroborated the experimental results. Furthermore, BDP-Se was incorporated into a novel cotton swab-based device for palladium detection in aqueous solutions (with up to 60 % water), demonstrating its applicability in the solid state.
- The haunting challenge of the trends and pathway assessments on newly introduced non-indigenous species in European seasPublication . Outinen, Okko; Stæhr, Peter A. U.; Ribeiro, Romeu S.; Carbonell, Aina; Comas-González, Robert; Png-Gonzalez, Lydia; Vázquez-Luis, Maite; Florin, Ann Britt; Naddafi, Rahmat; Gittenberger, Arjan; Jakobsen, Hans; Costa, Ana C.; Parente, Manuela I.; Dragičević, Branko; Dulčić, Jakov; Petović, Slavica; Orlando-Bonaca, Martina; Mavrič, Borut; Bartilotti, Cátia; Lobo-Arteaga, Jorge; Tuaty-Guerra, Miriam; Viard, Frédérique; Massé, Cécile; Castriota, Luca; Livi, Silvia; Galanidi, Marika; Zenetos, Argyro; Carvalho, Natacha; Canning-Clode, João; Parretti, Paola; Ramalhosa, Patrício; Castro, Nuno; MARE - Centro de Ciências do Mar e do Ambiente; ElsevierThe spread of aquatic non-indigenous species (NIS) is recognised as a major threat to the recipient regions ecosystems. The present study reviewed all NIS that have been introduced to the marine waters of the European Union (EU) until 2021, and their introduction pathways. Further, the study statistically analysed temporal trends in new NIS introductions and addressed uncertainties in relation to transporting pathways. Time-series analyses indicated that the observed trends in new NIS introductions have followed smoothly increasing trajectories for the entire study area, Mediterranean Sea, North-East Atlantic Ocean, and the Baltic Sea, whereas abrupt increase was detected for the Black Sea. It is noteworthy that the increasing trends started to slow down at the end of 2010s. Strongly increased research interest towards marine invasions since the early 2000s, and new environmental policies likely affected the observed trends. Future updates will be key to assessing whether this slowdown is truly a persisting trend or only an anomaly in the long term. The pathway assessment suffered from notable uncertainties, as the assigned confidence levels for pathways were low or unassigned for a large proportion of the introduced NIS in all study regions. Transport by shipping vectors was assigned as the most common pathway (51%) for new NIS introductions to EU seas, although there was very rarely direct evidence of this. The study highlights the need to overcome the pathway uncertainties, as robust information on introduction pathways is critical to manage new NIS introductions effectively.
- Development and real-world deployment of a multi-agent system to support the operation of renewable energy communitiesPublication . Patrício, João Tabanêz; Lopes, Tiago; Rocha, André; Martins, João; Amaral Lopes, Rui; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; ElsevierDespite the ongoing measures to support the development of Renewable Energy Communities (RECs), effectively managing energy production, consumption, and sharing, while balancing members’ needs, remains a major challenge. This paper presents a Multi-Agent System-based Community Energy Management System, designed to manage interactions and real-time energy exchanges within a REC to tackle the referred challenge in line with European legislation. The developed system has been deployed in real-world conditions considering a REC located in Portugal, unlike previous studies that rely on simulation. Additionally, the energy flexibility provided by second-life batteries has been controlled by the system to improve self-consumption of local generation and increase benefits of energy sharing in different scenarios. The real-world case study revealed that the developed system demonstrated effective operation, including emergency procedures to prevent deep discharge of batteries. The collected results also show that collective self-consumption with dynamic sharing coefficients is the most interesting REC configuration in terms of global cost savings, reducing energy bills by 25–28 % and 20–24 % when comparing to scenarios where individual self-consumption with fixed and dynamic sharing coefficients are applied, respectively.
- The unit f-sequence for primitive-based fPublication . Brison, Owen J.; Nogueira, J. Eurico; DM - Departamento de Matemática; Elsevier Science B.V., Amsterdam.We study the behaviour with respect to the operation of lifting of the unit g -sequence, where g(t) is a primitive polynomial. We also study the unit f -sequence for primitive-based f(t) and show it is closely related to the lifted unit g -sequence where f(t) is based on g(t).
- Global power sharing and virtual inertia control for the interlinking modular universal converter in standalone hybrid ac/dc microgridPublication . Gutiérrez-Escalona, Javier; Roncero-Clemente, Carlos; Matiushkin, Oleksandr; Azizi, Mohammadreza; Martins, João; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Elsevier Science Publisher B.V.Hybrid ac/dc microgrids (HMGs) have gained significant attention in recent years for their efficient integration of distributed energy resources and their capability to operate independently from the grid during islanded mode. The bidirectional interlinking converter (BIC) is the key element that coordinates power exchange between sub-grids to achieve precise power sharing. This work introduces a hierarchical control strategy providing adaptive bidirectional virtual inertia (BVI) support and precise global power sharing in a standalone HMG. Besides, the proposed control strategy was designed and validated for the recently introduced modular universal converter (MUC) topology with voltage boosting capability, demonstrating its effectiveness in performing advanced BIC functionalities such as inertia support. The hardware-in-the-loop tests conducted in real time show that the proposed strategy achieves zero power sharing error while enhancing the voltage and frequency stability through BVI transferring. Furthermore, the performance of the MUC as BIC with advanced functionalities is demonstrated, reaffirming its strong potential as a highly modular and standardized power converter solution for standalone HMGs.