31 documents found, page 1 of 4
GNSS and accelerometers data fusion in large structures monitoring
Lima, J. N.; Oliveira, S.; Henriques, M.The monitoring systems have two main objectives: (i) to evaluate the safety conditions and durability of the infrastructures and to develop a better understanding about their day-to-day behaviour; (ii) to detect the occurrence of special events that might jeopardize the safety of the structure. To reach the first objective it is mandatory to create a database as most extensive as possible to support an analysis...
Quality assessment of GNSS with short-length session in the displacement measur...
Lima, J. N.; Conde, V.; Candeias, H.After a large set of GNSS tests carried out on a 325 m baseline, with different length observation sessions, we assessed the quality of GNSS with short-length sessions to monitoring the displacements of a large embankment dam, in south of Portugal. The GNSS campaigns were performed at the same time of classic geodetic observation campaigns, with Leica TCA2003 tacheometer and Leica NA2 optical level, and the res...
Port infrastructure monitoring (Madeira Island, Portugal) through GNSS, inertia...
Pereira, M.; Teodoro, A.; Veloso Gomes, F.; Henriques, M. J.; Lima, J. N.; Oliveira, S.Port infrastructures as breakwaters, are specially designed to be exposed to the most adverse and extreme conditions. Actions such as wind, waves, tides, sediment dynamics and ships anchoring are factors that can weaken these infrastructures over time. The present work focuses on the control of the stability of Funchal Port breakwater (Madeira Island-Portugal).
Assessing the quality of an UAV-based orthomosaic and surface model of a breakw...
Henriques, M. J.; Fonseca, A. M.; Roque, D.; Lima, J. N.; Marnoto, J.The low price and the quality of the products derived from photographs taken by cameras mounted on unmanned aerial vehicles (UAV) turn them very attractive to be used in several situations, namely when the area that needs to be covered hasn’t a large extension or when is necessary to have data, like coordinates of points, on a periodic basis. The monitoring of the behavior of breakwaters fall is this category o...
Utilização de veículos aéreos não tripulados para a monitorização de infraestru...
Fonseca, A. M.; Roque, D.; Lima, J. N.; Henriques, M. J.; Marnoto, J.O presente relatório apresenta uma experiência de aquisição de fotografias aéreas utilizando um veículo aéreo não tripulado (VANT) para recolha de informação geográfica do quebra-mar da Ericeira, com o objetivo de testar a capacidade destes dados para produção de ortofotomapas e modelos numéricos de superfície para monitorização de infraestruturas ao longo do tempo. A experiência foi realizada numa colaboração ...
Long-term geodetic displacements. Evaluating the quality of measured displacements
Henriques, M. J.; Oliveira, S.; Lima, J. N.The displacements measured by geodetic methods have long been used by civil engineers to the structural safety control. For a normal structural behaviour it is possible to establish a simple model for describing the relations between the loads (gravity, temperature, hydrostatic pressure, etc.) and the structural response (e.g. displacements). Using data from many geodetic campaigns – displacements, campaigns da...
Fusão de deslocamentos medidos com o GNSS e acelerações
Lima, J. N.; Oliveira, S.; Henriques, M.A fusão de dados provenientes de diferentes tipos de instrumentos pode dar uma informação mais completa para a monitorização do comportamento de estruturas de engenharia civil, em particular nas pontes de grande vão. O objectivo da fusão de deslocamentos medidos com o GNSS e de acelerações, é tirar partido da precisão conseguida com o GNSS, em baixas frequências, e da grande sensibilidade dos acelerómetros, em ...
Sistemas de Controlo e Análise Estrutural do Quebramar do Porto do Funchal
Pereira, M.; Teodoro, A.; Veloso Gomes, F.; Henriques, M.; Lima, J. N.; Oliveira, S.O principal objetivo deste trabalho é o de analisar o comportamento do quebramar do porto do Funchal através da medição dos seus movimentos (deslocamentos e acelerações) e deteção de alterações morfológicas, utilizando para o efeito sistemas de posicionamento por satélite (GNSS), técnicas clássicas de topografia, acelerómetros e através da simulação do seu comportamento com base em modelos numéricos e físicos, ...
SMOOTHING GNSS TIME SERIES WITH ASYMMETRIC MOVING AVERAGES
Lima, J. N.; Casaca, J. M.There is an increasing trend to apply GNSS continuous observation of short baselines to the monitoring of engineering works, such as bridges and dams, for their structural analysis and safety control. In the case of large dams, one important application of the GNSS continuous observation is the establishment of early warning systems that demand accurate, frequently updated information and where the analysis of ...
Measuring Inclinations in Cabril Dam with an Optoelectronic Sensor
Henriques, M. J.; Lima, J. N.; Oliveira, S.A high precision inclinometer was placed at the top gallery of Cabril dam, the highest dam in Portugal (132 m). Cabril dam has been presenting, since the first filling of the reservoir (1953), some horizontal cracks in the central upper zone. The dual axis inclinometer, with a recording measuring rate of 1 Hz, was installed for two days; during the same period a digital thermometer, for recording air temperatur...