The purpose of the present study is to investigate the extreme values of the ice drift speed,which are also considered in the light of the magnitude of the simultaneous wind speed.The relationship between wind speed a...The purpose of the present study is to investigate the extreme values of the ice drift speed,which are also considered in the light of the magnitude of the simultaneous wind speed.The relationship between wind speed and ice drift speed is studied.The long-term ice drift data is collected by using local subsurface measurements based on acoustic Doppler current profilers(ADCP)in the Beaufort Sea during the period of 2006-2017.Upward-looking sonars(ULS)are deployed in order to observe the ice thickness as well as to identify events that correspond to open water conditions.The relationship between the ice drift speed and the wind speed is also investigated.It is found that the magnitude of the average ice drift speed is approximately 2.5%of the wind speed during the winter season.Estimation of the extreme values of the ice drift speed is studied by application of the average conditional exceedance rate(ACER)method.It is found that the extreme ice drift speed during the ice melt season(i.e.the summer season)is approximately20%-30%higher than that during the ice growth season(i.e.the winter season).The extreme ice drift speed can be effectively estimated based on the 2.5%wind speed.Moreover,the extreme ice drift speed can be obtained based on the extreme values of 2.5%of the wind speed based on multiplying with an amplification factor which varies in the range from 1.7 to 2.0 during the growth season,corresponding to increasing return periods of 10,25,50 and 100years.展开更多
The main challenge in predicting global responses of floating vessels in deepwater and uhra-deepwater areas comes from the system＇s coupled effect, tn this paper, the coupled approach is used to analyze effects of ri...The main challenge in predicting global responses of floating vessels in deepwater and uhra-deepwater areas comes from the system＇s coupled effect, tn this paper, the coupled approach is used to analyze effects of riser on floating system in deepwater. The analysis results show that the coupling effects of risers will mainly affect the low frequency （LF） motions of the system. That is because risers will provide the system with a significant low frequency （LF） damping which will vary with the sea states. Under storm sea state, the excitation term from drag force will govern the response. While under the moderate conditions, the damping effect of risers is more significant. In the practical engineering, the combination effect should be considered by other ways when the risers are omitted from the model.展开更多
基金Open Access funding provided by NTNU Norwegian University of Science and Technology(incl St.Olavs Hospital-Trondheim University Hospital)。
文摘The purpose of the present study is to investigate the extreme values of the ice drift speed,which are also considered in the light of the magnitude of the simultaneous wind speed.The relationship between wind speed and ice drift speed is studied.The long-term ice drift data is collected by using local subsurface measurements based on acoustic Doppler current profilers(ADCP)in the Beaufort Sea during the period of 2006-2017.Upward-looking sonars(ULS)are deployed in order to observe the ice thickness as well as to identify events that correspond to open water conditions.The relationship between the ice drift speed and the wind speed is also investigated.It is found that the magnitude of the average ice drift speed is approximately 2.5%of the wind speed during the winter season.Estimation of the extreme values of the ice drift speed is studied by application of the average conditional exceedance rate(ACER)method.It is found that the extreme ice drift speed during the ice melt season(i.e.the summer season)is approximately20%-30%higher than that during the ice growth season(i.e.the winter season).The extreme ice drift speed can be effectively estimated based on the 2.5%wind speed.Moreover,the extreme ice drift speed can be obtained based on the extreme values of 2.5%of the wind speed based on multiplying with an amplification factor which varies in the range from 1.7 to 2.0 during the growth season,corresponding to increasing return periods of 10,25,50 and 100years.
文摘The main challenge in predicting global responses of floating vessels in deepwater and uhra-deepwater areas comes from the system＇s coupled effect, tn this paper, the coupled approach is used to analyze effects of riser on floating system in deepwater. The analysis results show that the coupling effects of risers will mainly affect the low frequency （LF） motions of the system. That is because risers will provide the system with a significant low frequency （LF） damping which will vary with the sea states. Under storm sea state, the excitation term from drag force will govern the response. While under the moderate conditions, the damping effect of risers is more significant. In the practical engineering, the combination effect should be considered by other ways when the risers are omitted from the model.
