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  • Non-intrusive low-cost IoT-based hardware system for sustainable predictive maintenance of industrial pump systems
    Publication . Brito, Sergio; Azinheira, Gonçalo; Semião, Jorge; Sousa, Nelson; Pérez Litrán, Salvador
    Industrial maintenance has shifted from reactive repairs and calendar-based servicing toward data-driven predictive strategies. This paper presents a non-intrusive, low-cost IoT hardware platform for sustainable predictive maintenance of rotating machinery. The system integrates an ESP32-S3 sensor node that captures vibration (100 kHz) and temperature data, performs local logging, and communicates wirelessly. An automated spectral band segmentation framework is introduced, comparing equal-energy, linear-width, nonlinear, clustering, and peak-valley partitioning methods, followed by a weighted feature scheme that emphasizes high-value bands. Three unsupervised one-class classifiers-transformer autoencoders, GANomaly, and Isolation Forest-are evaluated on these weighted spectral features. Experiments conducted on a custom pump test bench with controlled anomaly severities demonstrate strong anomaly classification performance across multiple configurations, supported by detailed threshold-characterization metrics.
    2025-07-21Artigo científico Acesso aberto Ver mais
  • First assessment of blue carbon stocks, sequestration rates and potential sources since 1900 at Arguin Island (Mauritania)
    Publication . Martins, Márcio; Abrantes, Fatima; Aires, Tania; Rautenbach, Sarah; Engelen, Aschwin; Encarnação, João Pedro da Silva; Abecasis, David; Gandega, Cheikhna; Magalhães, Vitor; Brahim, Khallahi; Ebaye, Sidina; Barusseau, Jean-Paul; Freiwald, André; Barrena de los Santos, Carmen; Serrao, Ester A.; Santos, Rui
    Global blue carbon assessments are hindered by a lack of data from understudied seagrass regions, such as those of Western Africa. This study reports the first in situ records of organic carbon (OC) stocks and burial rates for seagrass beds at Arguin Island, Banc d'Arguin (Mauritania), Western Africa, measured in intertidal Zostera noltei and subtidal Cymodocea nodosa meadows. The major blue carbon sources in seagrass meadows since 1900 were assessed using sedimentary environmental DNA (eDNA) and chronostratigraphy. The OC stocks in the top 50 cm of the sediment cores were not significantly different between the beds of the two seagrass species and averaged 27.8±7.14 Mg C ha−1, which is 5 times higher than that in adjacent unvegetated sediments. The OC sequestration rate for the past 100 years was 10.3±1.4 g C m−2 year−1 in C. nodosa sediments and 12.3±5.9 g C m−2 year−1 in Z. noltei sediments. Sedimentary eDNA analysis revealed that the major OC source within the C. nodosa and Z. noltei sediments has been the seagrass species itself, with low contributions from allochthonous eDNA reads. Carbon sources in Z. noltei meadows were more diverse than those in C. nodosa meadows. In bare sediment, diatoms were the major carbon source. The present study demonstrates the potential of sedimentary eDNA to reveal the major sources of organic matter in blue carbon ecosystems, improving our understanding of the provenance of sedimentary OC and thus carbon cycling processes. Additionally, it provides new OC stock and sequestration rate measurements from a region of the world that remains underrepresented in global blue carbon assessments.
    2025-07-21Artigo científico Acesso aberto Ver mais