A mapping function between the Reynolds-averaged Navier-Stokes mean flow variables and transition intermittency factor is constructed by fully connected artificial neural network(ANN),which replaces the governing equa...A mapping function between the Reynolds-averaged Navier-Stokes mean flow variables and transition intermittency factor is constructed by fully connected artificial neural network(ANN),which replaces the governing equation of the intermittency factor in transition-predictive Spalart-Allmaras(SA)-γmodel.By taking SA-γmodel as the benchmark,the present ANN model is trained at two airfoils with various angles of attack,Mach numbers and Reynolds numbers,and tested with unseen airfoils in different flow states.The a posteriori tests manifest that the mean pressure coefficient,skin friction coefficient,size of laminar separation bubble,mean streamwise velocity,Reynolds shear stress and lift/drag/moment coefficient from the present two-way coupling ANN model almost coincide with those from the benchmark SA-γmodel.Furthermore,the ANN model proves to exhibit a higher calculation efficiency and better convergence quality than traditional SA-γmodel.展开更多
The clay mineralogy of 28 sandy-muddy transitional beach(SMT-Beach)sediments and surrounding mountain river sediments along the coasts of southeastern China was systematically investigated to reveal the sediment sourc...The clay mineralogy of 28 sandy-muddy transitional beach(SMT-Beach)sediments and surrounding mountain river sediments along the coasts of southeastern China was systematically investigated to reveal the sediment source-to-sink process variations of such beaches and their morphological indications.The results show that the clay mineral assemblages of these SMT-Beaches mainly comprise of almost equal illite(~30%),kaolinite(~28%),chlorite(~22%),and smectite(~20%)contents.From the surrounding mountain rivers to the SMT-Beaches,clay mineral assemblages show distinct spatial changes characterized by a large decrease(~40%)in kaolinite,whereas the other three clay minerals present relative increases,especially clear for smectite.The muddy sediment sources of SMT-Beaches inferred from the clay mineralogy are mainly derived from nearby mountain rivers coupled with long-distance transport and penetration of the Changjiang River.The sandy sediments of these beaches are predominantly sourced from nearby mountain rivers,the weathering products of surrounding rocks in both mainland and island environments,and erosion of the“Old Red Sand”and“Red Soil Platform”.However,the sandy sediment sources of the SMT-Beaches are largely reduced because of the remarkable decrease in the river fluvial supply associated with intensive human activities such as dam construction and coastal reclamation.Subsequently,the sandy sections of SMT-Beaches present clear erosion and have revealed by both time series remote sensing images and a compilation of published literature.In contrast,the muddy sediment supply of SMT-Beaches is temporarily stable and relatively constant,resulting in the landward migration of the mudflats with relative transgression or accumulation.These findings highlight that the natural evolution processes of SMT-Beaches have been greatly reshaped by intensive human activities.展开更多
目的检验中文版自我管理和过渡期准备问卷[self-management and transition to adulthood with Rx=treatment(STARx)questionnaire]在青少年癫痫患者中的信度和效度。方法采用便利抽样法,选取436名确诊癫痫的青少年患者为研究对象,样本1...目的检验中文版自我管理和过渡期准备问卷[self-management and transition to adulthood with Rx=treatment(STARx)questionnaire]在青少年癫痫患者中的信度和效度。方法采用便利抽样法,选取436名确诊癫痫的青少年患者为研究对象,样本1共250例,采用条目水平的内容效度指数(item-level content validity index,I-CVI)和问卷水平的内容效度指数(scale-level content validity index,S-CVI)评价问卷的内容效度,采用探索性因子分析对量表结构进行探索,采用Cronbachα系数评价量表的内部一致性信度。样本2186例,采用验证性因子分析验证量表的结构效度,采用Cronbachα系数、Spearman-Brown系数和重测信度系数评价量表的信度。结果中文版STARx的总条目内容效度指数为0.981,条目水平的内容效度指数为0.833~1.000;问卷探索性因子分析,特征值>1的公因子有4个,累积方差贡献率为70.309%,且各条目在其公因子上的负荷值为0.636~0.831,较原问卷6个维度减少了2个维度;验证性因子分析显示,卡方比自由度(chi-square/degree of freedom,χ^(2)/df)为2.53(<3),近似误差均方根为0.091(<0.1),数据与模型的拟合度良好;问卷总的Cronbachα系数为0.917,折半信度为0.730,重测信度为0.940。结论STARx在青少年癫痫患者的检验中显示信度、效度良好,可作为评价癫痫青少年至成人过渡期准备水平的有效工具。展开更多
基金the financial supports provided by the National Natural Science Foundation of China(Nos.91852112 and 11988102)。
文摘A mapping function between the Reynolds-averaged Navier-Stokes mean flow variables and transition intermittency factor is constructed by fully connected artificial neural network(ANN),which replaces the governing equation of the intermittency factor in transition-predictive Spalart-Allmaras(SA)-γmodel.By taking SA-γmodel as the benchmark,the present ANN model is trained at two airfoils with various angles of attack,Mach numbers and Reynolds numbers,and tested with unseen airfoils in different flow states.The a posteriori tests manifest that the mean pressure coefficient,skin friction coefficient,size of laminar separation bubble,mean streamwise velocity,Reynolds shear stress and lift/drag/moment coefficient from the present two-way coupling ANN model almost coincide with those from the benchmark SA-γmodel.Furthermore,the ANN model proves to exhibit a higher calculation efficiency and better convergence quality than traditional SA-γmodel.
基金The National Natural Science Foundation of China under contract Nos 41930538,42076211 and 42076058the Scientific Research Foundation of the Third Institute of Oceanography,Ministry of Natural Resources under contract Nos 2022017 and 2019006the China Postdoctoral Science Foundation under contract No.2019M652248.
文摘The clay mineralogy of 28 sandy-muddy transitional beach(SMT-Beach)sediments and surrounding mountain river sediments along the coasts of southeastern China was systematically investigated to reveal the sediment source-to-sink process variations of such beaches and their morphological indications.The results show that the clay mineral assemblages of these SMT-Beaches mainly comprise of almost equal illite(~30%),kaolinite(~28%),chlorite(~22%),and smectite(~20%)contents.From the surrounding mountain rivers to the SMT-Beaches,clay mineral assemblages show distinct spatial changes characterized by a large decrease(~40%)in kaolinite,whereas the other three clay minerals present relative increases,especially clear for smectite.The muddy sediment sources of SMT-Beaches inferred from the clay mineralogy are mainly derived from nearby mountain rivers coupled with long-distance transport and penetration of the Changjiang River.The sandy sediments of these beaches are predominantly sourced from nearby mountain rivers,the weathering products of surrounding rocks in both mainland and island environments,and erosion of the“Old Red Sand”and“Red Soil Platform”.However,the sandy sediment sources of the SMT-Beaches are largely reduced because of the remarkable decrease in the river fluvial supply associated with intensive human activities such as dam construction and coastal reclamation.Subsequently,the sandy sections of SMT-Beaches present clear erosion and have revealed by both time series remote sensing images and a compilation of published literature.In contrast,the muddy sediment supply of SMT-Beaches is temporarily stable and relatively constant,resulting in the landward migration of the mudflats with relative transgression or accumulation.These findings highlight that the natural evolution processes of SMT-Beaches have been greatly reshaped by intensive human activities.
文摘目的检验中文版自我管理和过渡期准备问卷[self-management and transition to adulthood with Rx=treatment(STARx)questionnaire]在青少年癫痫患者中的信度和效度。方法采用便利抽样法,选取436名确诊癫痫的青少年患者为研究对象,样本1共250例,采用条目水平的内容效度指数(item-level content validity index,I-CVI)和问卷水平的内容效度指数(scale-level content validity index,S-CVI)评价问卷的内容效度,采用探索性因子分析对量表结构进行探索,采用Cronbachα系数评价量表的内部一致性信度。样本2186例,采用验证性因子分析验证量表的结构效度,采用Cronbachα系数、Spearman-Brown系数和重测信度系数评价量表的信度。结果中文版STARx的总条目内容效度指数为0.981,条目水平的内容效度指数为0.833~1.000;问卷探索性因子分析,特征值>1的公因子有4个,累积方差贡献率为70.309%,且各条目在其公因子上的负荷值为0.636~0.831,较原问卷6个维度减少了2个维度;验证性因子分析显示,卡方比自由度(chi-square/degree of freedom,χ^(2)/df)为2.53(<3),近似误差均方根为0.091(<0.1),数据与模型的拟合度良好;问卷总的Cronbachα系数为0.917,折半信度为0.730,重测信度为0.940。结论STARx在青少年癫痫患者的检验中显示信度、效度良好,可作为评价癫痫青少年至成人过渡期准备水平的有效工具。
