http://repositorio.lnec.pt:8080/jspui/handle/123456789/70 2026-10-26T10:07:25Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1020022 Gestão técnica da unidade de hidráulica metrológica do LNEC: Estrutura dos planos de manutenção e de segurança Ribeiro, A.; Simões, C.; Coelho, G.; Martins, A.; Mendes, R. A.; Fernandes, H. A Unidade de Hidráulica Metrológica (UHM) do LNEC é fundamental para o reconhecimento do LNEC como Instituto Designado para as grandezas caudal e velocidade de escoamento de líquidos, garantindo a rastreabilidade metrológica essencial para a gestão dos recursos hídricos em setores como abastecimento de água, agroindústria e tratamento de águas residuais. Este relatório detalha a estrutura dos planos de manutenção e de segurança que suportam a operação da infraestrutura hidráulica da UHM, composta por sistemas mecânicos, hidráulicos, elétricos e eletrónicos complexos. São abordadas as práticas de manutenção preventiva, corretiva e preditiva, visando a confiança e a qualidade das calibrações. Os planos de segurança incluem a avaliação de riscos, medidas preventivas, equipamentos de proteção, procedimentos de emergência, capacitação do pessoal, auditorias e comunicação, assegurando a segurança das pessoas e o cumprimento dos requisitos da ISO/IEC 17025. 2026-01-01T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019634 A Metrologically Validated Cost-Effective Solution for Laboratory Measurement of Long-Term Deformations in Construction Materials Fathi, A.; Martins, L.; Pereira, J.; Vasconcelos, G.; Azenha, M. Sebastiano Candamano Abstract - Investigating the long-term performance of building materials, such as drying shrinkage,moisture expansion, creep, and others, usually requires long-lasting tests with a high number of specimens. Given the initial costs, required data acquisition systems, and the time allocated, conventional sensors like LVDTs become costly for such long-term experimental studies. This article proposes an innovative cost-effective solution combining optical microscopy imaging, 3D printed sliding rulers, and Python-based artificial vision to overcome these limitations. The 3D printed rulers establish a local physical reference frame, while the artificial vision system uses contour detection and point tracking of optical targets to quantify displacements. Unlike continuous monitoring systems, the proposed solution utilises a discontinuous point-tracking approach, allowing a single USB microscope to monitor an unlimited number of specimens while maintaining the possibility for moisture exchange between the material surface and the environment. The system was metrologically validated against a laser interferometer, achieving an expanded instrumental uncertainty of 0.0042 mm (4.2 μm), determined through strict calibration. These results demonstrate that the proposed solution delivers accuracy comparable to conventional sensors but with significantly higher scalability and lower cost, making it highly suitable for extensive long-term experimental programmes. 2026-02-13T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019265 Reforço da capacidade de medição de parâmetros de textura superficial no LNEC - Perfilómetro óptico com sonda de luz branca Lages Martins, L.; Pinheiro, A. Este relatório descreve o procedimento de ensaio para a medição de parâmetros de textura superficial com recurso a um perfilómetro óptico com sonda de luz branca, tendo em vista a utilização generalizada deste equipamento no âmbito dos estudos de investigação realizados pelo LNEC no domínio da Engenharia Civil, relacionados com materiais de engenharia, componentes, estruturas e produtos. 2025-12-01T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1018081 Influence of rainfall time series sample rate in the improvement of decision-making based on high intensity rainfall events Simões, C.; Ribeiro, A.; Almeida, M. C.; Covas, D.; Coelho, G.; Pinheiro, A. IMEKO Abstract - This study aims Lo assess whether data acquisition frequency can affect the understanding of high-intensity precipitation events. Time series from a weighing gauge and a weighhridge gauge installed at the sarne site were analysed, with rainfall intensity data acquisition frequencies of 10 seconds and 5 minutes, respectively. To check the consistency of the data ohtained by the two types of rainfall measuring instruments, a correlation analysis was carried out between the two time series. The results relating to acquisition frequency showed that, for an acquisition frequency of 5 minutes. there are significant losses of information (especially during heavy rainfall events) compared to acquisition frequencies of l0 seconds. The correlation analysis showed that the gauges are measuring correctly and that the data is accurate. 2024-08-01T00:00:00Z