A set of laboratory experiments are carried out to investigate the effect of following/opposing currents on wave attenuation.Rigid vegetation canopies with aligned and staggered configurations were tested under the co...A set of laboratory experiments are carried out to investigate the effect of following/opposing currents on wave attenuation.Rigid vegetation canopies with aligned and staggered configurations were tested under the condition of various regular wave heights and current velocities,with the constant water depth being 0.60 m to create the desired submerged scenarios.Results show that the vegetation-induced wave dissipation is enhanced with the increasing incident wave height.A larger velocity magnititude leads to a greater wave height attenuation for both following and opposing current conditions.Moreover,there is a strong positive linear correlation between the damping coefficientβand the relative wave height H_(0)/h,especially for pure wave conditions.For the velocity profile,the distributions of U_(min)and U_(max)show different patterns under combined wave and current.The time-averaged turbulent kinetic energy(TKE)vary little under pure wave and U_(c)=±0.05 m/s conditions.With the increase of flow velocity amplitude,the time-averaged TKE shows a particularly pronounced increase trend at the top of the canopy.The vegetation drag coefficients are obtained by a calibration approach.The empirical relations of drag coefficient with Reynolds and Keulegane-Carpenter numbers are proposed to further understand the wave-current-vegetation interaction mechanism.展开更多
目的探讨凝血功能与2型糖尿病患者合并外周动脉斑块的相关性。方法纳入2022年5-8月在我院内分泌科住院治疗的2型糖尿病患者269例,分别根据有无颈动脉斑块和有无下肢动脉斑块将患者分为颈动脉斑块组(131例)和无颈动脉斑块组(138例)、下...目的探讨凝血功能与2型糖尿病患者合并外周动脉斑块的相关性。方法纳入2022年5-8月在我院内分泌科住院治疗的2型糖尿病患者269例,分别根据有无颈动脉斑块和有无下肢动脉斑块将患者分为颈动脉斑块组(131例)和无颈动脉斑块组(138例)、下肢动脉斑块组(134例)和无下肢动脉斑块组(135例)。比较各组患者的一般临床资料及凝血功能指标的差异,采用logistic回归分析评估2型糖尿病合并外周动脉斑块的独立影响因素。结果颈动脉斑块组患者的纤维蛋白原水平高于无颈动脉斑块组[3.15(2.79,3.79)g/L vs 2.99(2.66,3.42)g/L,P=0.005]。logistic回归分析显示,纤维蛋白原为2型糖尿病合并颈动脉斑块的独立危险因素(OR=1.338,95%CI 1.061~2.078,P<0.05)。下肢动脉斑块组和无下肢动脉斑块组凝血功能指标差异无统计学意义(均P>0.05)。结论2型糖尿病合并不同部位外周动脉斑块与凝血功能的相关性不同。合并颈动脉斑块的患者纤维蛋白原水平较无颈动脉斑块的患者升高,且在控制其他混杂因素后纤维蛋白原是颈动脉斑块发生的独立危险因素;而合并下肢动脉斑块与凝血功能指标无关。展开更多
目前主流的基于逐点特征提取的深度学习网络模型在获取点云局部精细几何结构信息的能力上还存在一定不足。同时注意力机制被引入到了点云处理领域以求取得更高的分类分割精度,但随之而来的却是模型训练内存消耗的激增以及训练效率的下...目前主流的基于逐点特征提取的深度学习网络模型在获取点云局部精细几何结构信息的能力上还存在一定不足。同时注意力机制被引入到了点云处理领域以求取得更高的分类分割精度,但随之而来的却是模型训练内存消耗的激增以及训练效率的下降。基于此,开发了一种新的深度学习网络(point position attention network,PointPAN)。通过逐点自注意力的方式引入注意力机制以及重新设计位置信息聚合算子解决上述问题。PointPAN的模型训练内存消耗量仅为其他引入注意力机制的深度学习网络模型的不到一半,同时最终模型在分类分割精度等性能指标上基本一致甚至略高。展开更多
In recent years,regional floods and typhoons have occurred in the Yangtze Estuary.Changing dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of ...In recent years,regional floods and typhoons have occurred in the Yangtze Estuary.Changing dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of the Yangtze Estuary.Based on the field measurement data and theoretical derivation,this paper analyzed the changing process of runoff-sediment discharge into the sea after the operation of the Three Gorges Project(TGP),and the tidal dynamics and sediment variation characteristics of the Yangtze Estuary.The erosion of South Branch mainly occurs in the channel below-10 m contour,and the riverbed volume below contours 0 m and-10 m has a good correlation with the sediment discharge of Datong Station in the previous year.On this basis,the ratio of the horizontal distance from the starting point to the section centroid below the average water level(B_c)and the water depth at the section centroid(H_c)was proposed to describe the change of the section shape.The relationships between the water-diverting ratio,the sediment-diverting ratio and the water-diverting angle,the conditions of runoff and sediment discharge from the upper reach and the characteristics of the riverway section were established,and the theoretical calculation equations of the water-diverting ratio,the sediment-diverting ratio and the diverting angle of each bifurcation were also established.展开更多
基金financially supported by the National Key Research and Development Program of China(2023YFC3208501)the National Natural Science Foundation of China(Grant Nos.U2340225,51979172)+2 种基金the Nanjing Hydraulic Research Institute Special Fund for Basic Scientific Research of Central Public Research Institutes(Y223002,Y220013)the CRSRI Open Research Program(Grant No.CKWV20221007/KY)the Post-Three Gorges Sediment Research Project of MWR(ProjectⅢ:Impact and Countermeasures of the Three Gorges Project on the Stability of the Shoal and Channel and Habitat of Yangtze River Estuary)。
文摘A set of laboratory experiments are carried out to investigate the effect of following/opposing currents on wave attenuation.Rigid vegetation canopies with aligned and staggered configurations were tested under the condition of various regular wave heights and current velocities,with the constant water depth being 0.60 m to create the desired submerged scenarios.Results show that the vegetation-induced wave dissipation is enhanced with the increasing incident wave height.A larger velocity magnititude leads to a greater wave height attenuation for both following and opposing current conditions.Moreover,there is a strong positive linear correlation between the damping coefficientβand the relative wave height H_(0)/h,especially for pure wave conditions.For the velocity profile,the distributions of U_(min)and U_(max)show different patterns under combined wave and current.The time-averaged turbulent kinetic energy(TKE)vary little under pure wave and U_(c)=±0.05 m/s conditions.With the increase of flow velocity amplitude,the time-averaged TKE shows a particularly pronounced increase trend at the top of the canopy.The vegetation drag coefficients are obtained by a calibration approach.The empirical relations of drag coefficient with Reynolds and Keulegane-Carpenter numbers are proposed to further understand the wave-current-vegetation interaction mechanism.
文摘目的探讨凝血功能与2型糖尿病患者合并外周动脉斑块的相关性。方法纳入2022年5-8月在我院内分泌科住院治疗的2型糖尿病患者269例,分别根据有无颈动脉斑块和有无下肢动脉斑块将患者分为颈动脉斑块组(131例)和无颈动脉斑块组(138例)、下肢动脉斑块组(134例)和无下肢动脉斑块组(135例)。比较各组患者的一般临床资料及凝血功能指标的差异,采用logistic回归分析评估2型糖尿病合并外周动脉斑块的独立影响因素。结果颈动脉斑块组患者的纤维蛋白原水平高于无颈动脉斑块组[3.15(2.79,3.79)g/L vs 2.99(2.66,3.42)g/L,P=0.005]。logistic回归分析显示,纤维蛋白原为2型糖尿病合并颈动脉斑块的独立危险因素(OR=1.338,95%CI 1.061~2.078,P<0.05)。下肢动脉斑块组和无下肢动脉斑块组凝血功能指标差异无统计学意义(均P>0.05)。结论2型糖尿病合并不同部位外周动脉斑块与凝血功能的相关性不同。合并颈动脉斑块的患者纤维蛋白原水平较无颈动脉斑块的患者升高,且在控制其他混杂因素后纤维蛋白原是颈动脉斑块发生的独立危险因素;而合并下肢动脉斑块与凝血功能指标无关。
文摘目前主流的基于逐点特征提取的深度学习网络模型在获取点云局部精细几何结构信息的能力上还存在一定不足。同时注意力机制被引入到了点云处理领域以求取得更高的分类分割精度,但随之而来的却是模型训练内存消耗的激增以及训练效率的下降。基于此,开发了一种新的深度学习网络(point position attention network,PointPAN)。通过逐点自注意力的方式引入注意力机制以及重新设计位置信息聚合算子解决上述问题。PointPAN的模型训练内存消耗量仅为其他引入注意力机制的深度学习网络模型的不到一半,同时最终模型在分类分割精度等性能指标上基本一致甚至略高。
基金financially supported by the Key Laboratory of Estuarine&Coastal Engineering,Ministry of Transport Open Research Program (Grant No.KLECE202001)CRSRI Open Research Program (Grant No.CKWV20221007/KY)+4 种基金the National Natural Science Foundation of China (Grant No.51979172)Jiangsu Provincial Water Conservancy Technology Project (Grant Nos.2020002,2021025,and 2021029)Fundamental Research Funds for Central Public Welfare Research Institutes (Y223002)Innovation Team Project of Estuarine and Coastal Protection and Management (Grant No.Y220013)the Major Scientific Projects of the Ministry of Water Resources (Grant No.SKS-2022087)。
文摘In recent years,regional floods and typhoons have occurred in the Yangtze Estuary.Changing dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of the Yangtze Estuary.Based on the field measurement data and theoretical derivation,this paper analyzed the changing process of runoff-sediment discharge into the sea after the operation of the Three Gorges Project(TGP),and the tidal dynamics and sediment variation characteristics of the Yangtze Estuary.The erosion of South Branch mainly occurs in the channel below-10 m contour,and the riverbed volume below contours 0 m and-10 m has a good correlation with the sediment discharge of Datong Station in the previous year.On this basis,the ratio of the horizontal distance from the starting point to the section centroid below the average water level(B_c)and the water depth at the section centroid(H_c)was proposed to describe the change of the section shape.The relationships between the water-diverting ratio,the sediment-diverting ratio and the water-diverting angle,the conditions of runoff and sediment discharge from the upper reach and the characteristics of the riverway section were established,and the theoretical calculation equations of the water-diverting ratio,the sediment-diverting ratio and the diverting angle of each bifurcation were also established.
