Pitting initiation on 304 stainless steel grades was investigated in alternating temperature pore solutions to simulate pitting on stainless steel rebar in a tropical marine environment. The results suggested that a larger amplitude of alternating temperature heavily doped the passive film, reduced the film’s thickness and increased the (Fe3+ox + Fe3+hy)/Fe2+ox and Cr3+hy/Cr3+ox ratios in the film. Alternating temperatures more significantly degraded the passive film and intensified the pitting sensitivity on the stainless steel when compared with the average temperatures of the alternating temperature cycles. More pitting initiation sites were observed on the samples that experienced the 22–60 °C and 22–70 °C alternating temperature cycles than their counterparts in 50 °C and 60 °C solutions, respectively.
Health monitoring, detection, and safety assessment of high-piled wharf structures are key problems to be solved urgently in the field of maritime transport engineering. An optimal method for placing accelerometers for monitoring a high-piled wharf structure is presented in this paper. In this method, a partitioned genetic algorithm strategy is proposed based on the frequency and vibration modes of the high-piled wharf obtained by a modal analysis using the finite element method. The modal assurance criterion matrix is used as an evaluation index of sensor placement results. Subsequently, the sensor placement scheme obtained by the proposed method is applied to a reducedscale model of a high-piled wharf to validate the method. The results demonstrate that the proposed sensor optimal placement method reduces the number of accelerometers and improves the calculation efficiency by ensuring relatively complete information on the high-piled wharf structure.
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