Fatigue life analysis of automotive key parts based on improved peak‐over‐threshold method

Ultra-long return level estimation of extreme wind speed based on the deductive method

Acoustic reflection measurements of seabed elevation were made at Stanhope Beach, Prince Edward Island, during three successive storms in October-November 1989. The instruments were located approximately 200 m offshore on the seaward face of a shore parallel bar in a mean water depth of 2.2 m. Bed elevation measurements were made at 30-min intervals with a range resolution of -+ 1 mm at horizontal spacings between 22 cm and 1.5 m, using an array of four acoustic sounders operating at 1, 2.25, and 5 MHz. It is shown that such an array can be used as (1) an interferometer to determine bedform properties and migration rates, (2) a leveling device to determine changes in local bottom slope, and (3) an erosion/deposition gauge. In the interferometric mode, time domain autocorrelation and cross-correlation analyses of the bottom elevations are used to estimate the wavelengths, migration rates, and migration directions of sand ripples and megaripples. The ripple wavelengths (10-15 cm) and heights (3-5 cm) are comparable to measurements made by divers. Ripple migration rates were 1-6 cm h -1 directed offshore in the direction of the mean shore normal near-bottom current and increased with increasing mean current speed. Evidence of megaripple-like features (2-5 cm height; 1.5-3 m length) is found, also migrating in the direction of the mean shore normal near-bottom drift, at speeds of about 20 cm h -1 . Bedload transport rates in the onshoreoffshore direction are estimated from the bedform migration rates. The ripple transport rate was small (an order of magnitude smaller than the transport of sediments in suspension by the mean offshore drift). In contrast, the large-scale bedform transport appears to have been comparable to the mean current transport of suspended sediment. Interestingly, it appears that the total bedform transport was comparable to that predicted by Watanabe's (1981) net bedload transport formula, provided a coefficient appropriate to irregular wave conditions is used. During the third and highest-energy storm event, the measurements indicate transition to flat bed, and generalized local erosion at a maximum rate of 8 cm h -1 . This erosion event was associated with a general shoreward migration of the bar.

Acoustic measurements of spatially-correlated depth changes in the nearshore zone during autumn storms

Detection and quantification of trends in time series of significant wave heights: An application in the Mediterranean Sea

Future floods using hydroclimatic simulations and peaks over threshold: An alternative to nonstationary analysis inferred from trend tests

An automated threshold selection method based on the characteristic of extrapolated significant wave heights

Study of sampling methods for assessment of extreme significant wave heights in the South China Sea

. Extreme significant wave heights are assessed in the South China Sea (SCS),
as assessments of wave heights are crucial for coastal and offshore
engineering. Two significant factors include the initial database and
assessment method. The initial database is a basis for assessment, and the
assessment method is used to extrapolate appropriate return-significant wave
heights during a given period. In this study, a 40-year (1975–2014) hindcast of tropical cyclone waves is used to analyse the extreme significant wave height, employing the peak over threshold (POT) method with the generalized Pareto distribution (GPD) model. The peak exceedances over a sufficiently large value (i.e. threshold) are fitted; thus, the return-significant wave heights are highly dependent on the threshold. To determine a suitable threshold, the sensitivity of return-significant wave heights and the characteristics of tropical cyclone waves are studied. The sample distribution presents a separation that distinguishes the high sample from the low sample, and this separation is within the stable threshold range. Because the variation in return-significant wave heights in this range is generally small and the separation is objectively determined by the track and intensity of the tropical cyclone, the separation is selected as a suitable threshold for extracting the extreme sample in the tropical cyclone wave. The asymptotic tail approximation and estimation uncertainty show that the selection is reasonable.

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Extreme significant wave height of tropical cyclone waves in the South China Sea

Wu, G.; Wang, J.; Liang, B., and Lee, D.Y., 2014. Simulation of detailed wave motions and coastal hazards. A laboratory experiment combined with numerical experiment had been carried out to test the applicability of a phase resolving model with non-hydrostatic pressure, SWASH, in simulating the time evolution of the detailed wave motion and hence in predicting the wave induced coastal hazards. Such model can also be used to investigate how fast wind waves adjust to new water depth when propagating over the rapidly varying water depth. A series of laboratory experiments were conducted at the 2-D wave flume. The surface wave elevation, underwater orbital motion and bottom pressure were measured at different locations of the flume when waves propagate over varying water depth. When the observed time series surface elevation together with orbital wave motion estimated from the observed waves are used as boundary condition, the SWASH model simulated the time series of surface elevation as well as wave...

Simulation of Detailed Wave Motions and Coastal Hazards

Wang, J.; Liang, B.C.; Li, H.J.; Pan, X.Y.; Lee, D.Y., and Xu, Y., 2016. Swash motion driven by the bore and prediction of foreshore profile change. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 492–497. Coconut Creek (Florida), ISSN 0749-0208. The prediction of a swash zone bed profile resulting from complex hydrodynamic processes is a challenging task. A series of laboratory experiments at a 2D wave flume were carried out to investigate the evolution of foreshore profiles and sediment transport in the swash zone. The swash motions and the changes of foreshore profiles at the different stages of foreshore evolution were measured for 12 cases of different combinations of wave height, wave period and water level for two different initial beach slopes (1/5 and 1/15). From the evolution of foreshore profiles detected by side looking video ...

https://bioone.org/journals/journal-of-coastal-research/volume-75/issue-sp1/SI75-099.1/Swash-Motion-Driven-by-the-Bore-and-Prediction-of-Foreshore/10.2112/SI75-099.1.pdf

Dongyoung Lee

Papers

An automated threshold selection method based on the characteristic of extrapolated significant wave heights

Study of sampling methods for assessment of extreme significant wave heights in the South China Sea

Extreme significant wave height of tropical cyclone waves in the South China Sea

Simulation of Detailed Wave Motions and Coastal Hazards

Swash Motion Driven by the Bore and Prediction of Foreshore Profile Change