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In this paper, a new algorithm for the real-time structural health monitoring of TLP (tension-leg platform) tendons is presented. The algorithm is based on bi-axial sensors installed along the tendon and top tension-meter. Then, the tension and bending moment along the line can be estimated by using the developed algorithm. For bending moment, a generalized-coordinate-based FEA (Finite Element Analysis) formulas with cubic interpolation are derived. For tension, analytical formulas with small angle assumption are derived. Hull-mooring-riser fully coupled software is used as a simulation tool to generate the corresponding numerical-sensor signals. To validate the developed algorithms, several case studies are conducted, considering variations in sensor spacing, line-failure detection, different boundary conditions, and ocean-storm conditions. The results show that the proposed algorithms can monitor the actual variations of tensions and bending moments (or axial and bending stresses) along the tendon with high accuracy, which means that the real-time monitoring of accumulated fatigue damage at hot-spots is also possible. The developed algorithm can also detect various line-failure scenarios by observing the change of stress signals. Its capability of real-time stress tracing in 10-yr and 100-yr storm conditions is also demonstrated. [ABSTRACT FROM AUTHOR]

Silva, A., Skagen, D. W., Uriarte, A., Massé, J., Santos, M. B., Marques, V., Carrera, P., Beillois, P., Pestana, G., Porteiro, C., and Stratoudakis, Y. 2009. Geographic variability of sardine dynamics in the Iberian Biscay region. – ICES Journal of Marine Science, 66: 495–508.The spatio-temporal variability in the distribution, demographic structure, recruitment, and mortality of sardine within the Iberian Biscay region is described using area-disaggregated data collected during acoustic surveys and at ports since the mid-1980s. Multiple regression models were used to describe log numbers-at-age obtained annually in ten areas covered by three surveys to test the existence of geographic differences in selectivity-at-age, recruitment strength, and mortality and to infer plausible migration routes. Within Iberian waters, sardine biomass was mainly concentrated off western Portugal and the Gulf of Cadiz. In the Bay of Biscay, biomass levels were comparable with those off western Portugal. Recruitment was localized in a few areas (northern Portugal and the Gulf of Cadiz and Bay of Biscay), intermingling with areas dominated by older fish. Recruitment was generally asynchronous among areas, although some recruitment peaks were noticeable across wider regions. Spatial patterns related to strong and weak year classes and year-class slopes were also noted. Clearly distinct dynamics were not evidenced within the Atlanto–Iberian sardine stock area, but the validity of the northern limit was questioned by the connection between sardine dynamics in the Bay of Biscay and the Cantabrian Sea. The results provided some evidence consistent with the hypothesis of sardine movement from recruiting grounds to areas farther along the coast as they grow. [ABSTRACT FROM PUBLISHER]

We investigate spatial and temporal variations in sardine maturation patterns and discuss the implications for stock structure, using recent samples collected opportunistically across the species range and data collected regularly for the assessment of the Atlanto-Iberian stock. Maturity ogives were fitted to maturity-at-length data using Generalized Linear Models, and maturation patterns are summarized by length at first maturity (L 50). Sardine attain sexual maturity at a total length of 10.9–16.8cm. The percentage of mature small sardine increases from north to south across the Northeast Atlantic. L 50 is low in the Mediterranean and Moroccan waters, but maturation is delayed towards the limits of the species'' range. Sardine mature smaller in the Gulf of Cadiz than in other areas of the Atlanto-Iberian stock, although there is no indication of a different maturation pattern north of the stock boundary. These results are not sufficient to review the stock structure of sardine, but question the hypothesis of homogeneous biological properties of sardine populations within the stock area. Sardine maturation length reduced and the spawning period extended in western Iberia during the past two decades. Associated increases in fish condition and fat reserves during the summer feeding season suggest that variations in reproductive traits may have been caused by environmentally driven changes in food availability. [Copyright &y& Elsevier]