Research on Wave Attenuation Performance of Floating Breakwater

In this study, a new type of double-pontoon floating breakwater was designed to improve the wave attenuation performance through the addition of suspended Savonius propeller-blade. Its hydrodynamic characteristics were studied through numerical simulations and performance-testing experiment. The following investigations were performed in this study: Firstly, wave theory and hydrodynamic theory were combined to calculate the wave attenuation performance and motion response of double-pontoon floating breakwater under linear wave conditions. The numerical results showed that the wave attenuation performance was better under a specific wave period and height, the transmission coefficient reached a relatively small value, and the mooring line tension responded periodically and satisfied the condition of maximum breaking force. Secondly, three key geometric parameters of breakwater were researched, including the relative spacing of pontoons, the relative spacing between pontoons and blades, and the height–diameter ratio of Savonius blades. The calculation results showed that the pontoon spacing was closer to the wavelength and the breakwater wave attenuation performance was better. Lastly, experimental tests were also performed on the new double-pontoon floating breakwater and the results showed that the wave attenuation performance and numerical projections were basically the same, which verified the validity and effectiveness of the design method.

Mechanotransduction-dependent control of stereocilia dimensions and row identity in inner hair cells

SummaryActin-rich structures like stereocilia and microvilli are assembled with precise control of length, diameter, and relative spacing. We found that developmental widening of the second-tallest stereocilia rank (row 2) of mouse inner hair cells correlated with the appearance of mechanotransduction. Correspondingly, Tmc1KO/KO;Tmc2KO/KO or TmieKO/KO hair cells, which lack transduction, have significantly altered stereocilia lengths and diameters. EPS8 and the short splice isoform of MYO15A, identity markers for row 1 (tallest), lost their row exclusivity in transduction mutants, a result that was mimicked by block of transduction channels. Likewise, the heterodimeric capping protein subunit CAPZB and its partner TWF2 lost their row 2 tip localization in mutants, and GNAI3 failed to accumulate at row 1 tips. Redistribution of marker proteins was accompanied by increased variability in stereocilia height. Transduction channels thus specify and maintain row identity and control addition of new actin filaments to increase stereocilia diameter.

Effect of relative spacing on wake turbulence under wave-current flow

This paper reports the findings of an experimental study carried out in a laboratory flume to investigate the interaction of a surface wave with a unidirectional current over submerged tandem (bed mounted two in-line) hemispheres. The pitch-to-height ratio of the hemispheres was varied to spawn d-type (L/d = 2), intermediate (L/d = 4), and k-type (L/d = 8) relative spacing. The observations are focused on the changes induced in the mean velocity, turbulence intensity, Reynolds shear stress, and the frictional contributions of burst-sweep cycle to shear stress due to superposition of surface waves on the ambient flow. The consequences from the present experiment showed that the stream-wise velocity fluctuation follows the normal Gaussian distribution at upstream of hemispheres. Further, the joint probability density function showed that the superimposed surface waves on the current are capable of modulating the turbulent eddies with a larger band of energy and frequency spectrum compared to current-only flow.