In 1994,Townend proposed a method to calculate the relative changes in various wave characteristics and structure-related parameters due to sea level rise for regular waves.The method was extended to irregular waves b...In 1994,Townend proposed a method to calculate the relative changes in various wave characteristics and structure-related parameters due to sea level rise for regular waves.The method was extended to irregular waves by Cheon and Suh in 2016.In this study,this method is further extended to include the effect of future change in offshore wave height and the sea level rise.The relative changes in wavelength,refraction coefficient,shoaling coefficient,and wave height in nearshore area are presented as functions of the relative changes in water depth and offshore wave height.The calculated relative changes in wave characteristics are then used to estimate the effect of sea level rise and offshore wave height change on coastal structures by calculating the relative changes in wave run-up height,overtopping discharge,crest freeboard,and armor weight of the structures.The relative changes in wave characteristics and structure-related parameters are all expressed as a function of the relative water depth for various combinations of the relative changes in water depth and offshore wave height.展开更多
Transcranial focused ultrasound is a booming noninvasive therapy for brain stimuli. The Kelvin–Voigt equations are employed to calculate the sound field created by focusing a 256-element planar phased array through a...Transcranial focused ultrasound is a booming noninvasive therapy for brain stimuli. The Kelvin–Voigt equations are employed to calculate the sound field created by focusing a 256-element planar phased array through a monkey skull with the time-reversal method. Mode conversions between compressional and shear waves exist in the skull. Therefore, the wave field separation method is introduced to calculate the contributions of the two waves to the acoustic intensity and the heat source, respectively. The Pennes equation is used to depict the temperature field induced by ultrasound. Five computational models with the same incident angle of 0？and different distances from the focus for the skull and three computational models at different incident angles and the same distance from the focus for the skull are studied. Numerical results indicate that for all computational models, the acoustic intensity at the focus with mode conversions is 12.05%less than that without mode conversions on average. For the temperature rise, this percentage is 12.02%. Besides, an underestimation of both the acoustic intensity and the temperature rise in the skull tends to occur if mode conversions are ignored. However, if the incident angle exceeds 30？, the rules of the over-and under-estimation may be reversed. Moreover,shear waves contribute 20.54% of the acoustic intensity and 20.74% of the temperature rise in the skull on average for all computational models. The percentage of the temperature rise in the skull from shear waves declines with the increase of the duration of the ultrasound.展开更多
考虑到砰击载荷的强非线性、随机性等特点,采用模型试验方法对圆筒型浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)受到波浪砰击作用的概率模型、环境激励规律进行研究。提出基于波面升高无因次化模型的方法,...考虑到砰击载荷的强非线性、随机性等特点,采用模型试验方法对圆筒型浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)受到波浪砰击作用的概率模型、环境激励规律进行研究。提出基于波面升高无因次化模型的方法,将少量的千年一遇和百年一遇砰击数据进行归一化拟合,以获得圆筒型FPSO的砰击载荷特性。结果显示,平台自身的运动对砰击概率有重要影响,且砰击发生概率加速阶段与砰击点的位置没有明显关系。随着砰击点位置的升高,圆筒型FPSO砰击载荷的量级总体呈上升趋势。由于圆筒型外翻结构的特点,与垂荡周期相近的谱峰周期海况所激发的砰击概率会提升。所构建的无因次化砰击概率模型和无因次化砰击载荷分布模型可对砰击载荷和砰击概率进行预测,并且模型可为长期模拟提供基础。展开更多
基金National Research Foundation of Korea(NRF)funded by Korea Ministry of Science,ICT and Future Planning(NRF-2014R1A2A2A01007921)
文摘In 1994,Townend proposed a method to calculate the relative changes in various wave characteristics and structure-related parameters due to sea level rise for regular waves.The method was extended to irregular waves by Cheon and Suh in 2016.In this study,this method is further extended to include the effect of future change in offshore wave height and the sea level rise.The relative changes in wavelength,refraction coefficient,shoaling coefficient,and wave height in nearshore area are presented as functions of the relative changes in water depth and offshore wave height.The calculated relative changes in wave characteristics are then used to estimate the effect of sea level rise and offshore wave height change on coastal structures by calculating the relative changes in wave run-up height,overtopping discharge,crest freeboard,and armor weight of the structures.The relative changes in wave characteristics and structure-related parameters are all expressed as a function of the relative water depth for various combinations of the relative changes in water depth and offshore wave height.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.81527901,11604361,and 91630309)
文摘Transcranial focused ultrasound is a booming noninvasive therapy for brain stimuli. The Kelvin–Voigt equations are employed to calculate the sound field created by focusing a 256-element planar phased array through a monkey skull with the time-reversal method. Mode conversions between compressional and shear waves exist in the skull. Therefore, the wave field separation method is introduced to calculate the contributions of the two waves to the acoustic intensity and the heat source, respectively. The Pennes equation is used to depict the temperature field induced by ultrasound. Five computational models with the same incident angle of 0？and different distances from the focus for the skull and three computational models at different incident angles and the same distance from the focus for the skull are studied. Numerical results indicate that for all computational models, the acoustic intensity at the focus with mode conversions is 12.05%less than that without mode conversions on average. For the temperature rise, this percentage is 12.02%. Besides, an underestimation of both the acoustic intensity and the temperature rise in the skull tends to occur if mode conversions are ignored. However, if the incident angle exceeds 30？, the rules of the over-and under-estimation may be reversed. Moreover,shear waves contribute 20.54% of the acoustic intensity and 20.74% of the temperature rise in the skull on average for all computational models. The percentage of the temperature rise in the skull from shear waves declines with the increase of the duration of the ultrasound.
文摘考虑到砰击载荷的强非线性、随机性等特点,采用模型试验方法对圆筒型浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)受到波浪砰击作用的概率模型、环境激励规律进行研究。提出基于波面升高无因次化模型的方法,将少量的千年一遇和百年一遇砰击数据进行归一化拟合,以获得圆筒型FPSO的砰击载荷特性。结果显示,平台自身的运动对砰击概率有重要影响,且砰击发生概率加速阶段与砰击点的位置没有明显关系。随着砰击点位置的升高,圆筒型FPSO砰击载荷的量级总体呈上升趋势。由于圆筒型外翻结构的特点,与垂荡周期相近的谱峰周期海况所激发的砰击概率会提升。所构建的无因次化砰击概率模型和无因次化砰击载荷分布模型可对砰击载荷和砰击概率进行预测,并且模型可为长期模拟提供基础。
