Artigos de Revista

Oscillating water column (OWC) wave energy converters can be integrated in harbor protection structures, such as vertical, rubble mound and piled breakwaters. The interaction between the incident wave and the structure, in which the OWC device is integrated, is significantly different, since the structure of the vertical breakwater is impermeable, while that of the rubble mound breakwater is porous. The performance of the OWC device for the three configurations is analyzed for a range of wave periods from 6 to 12 s and a wave height of 1 m. The OWC device integrated into the vertical breakwater shows the best performance (maximum mean pneumatic power of 70 kW), and the mean pneumatic power is globally 3 % higher than that of the OWC device integrated into the rubble mound breakwater (maximum mean pneumatic power of 67.4 kW). The performance of the OWC device integrated into the piled breakwater shows a similar trend to the OWC device integrated into the vertical breakwater for wave periods lower than 9 s, but it has a significant loss of performance for higher wave periods.

AbstractA novel methodology to evaluate railway track support conditions is currently being developed. This methodology is based on modal analysis of the multi-element system composed by the railway infrastructure and an instrumented railway vehicle. It belongs to the group of vibration-based structural damage identification methods and is focused on observing the characteristic frequencies of this multi-element system, which can be related with changes in the physical properties of the railway infrastructure. As opposed to other vehicle-based track monitoring methods, the proposed methodology should enable condition assessment of the railway infrastructure subgrade, an element that is often neglected during railway monitoring operations. Since this methodology is vehicle-based, it can be used to assess the entire extension of a railway infrastructure to gather data regarding the support conditions of the track. It can also assess the evolution of track support conditions over time by comparing different rides over the same railway stretch. An important aspect of this methodology that still lacks validation is the topic of characterizing track support conditions of a railway infrastructure through its natural frequencies. The suitability of the theoretical model behind this methodology is another aspect that needs to be assessed. Numerical simulations tests using the multibody simulation software Simpack® are currently being performed to address both topics. This paper describes some of the simulations performed in this context, including a description of the numerical models used. The obtained results support the selected theoretical model and the overall validity of the proposed methodology.