Formulation and numerical evaluation of a novel four-node quadrilateral element with continuous nodal stress（Q4-CNS）are presented.Q4-CNS can be regarded as an improved hybrid FE-meshless four-node quadrilateral elem...Formulation and numerical evaluation of a novel four-node quadrilateral element with continuous nodal stress（Q4-CNS）are presented.Q4-CNS can be regarded as an improved hybrid FE-meshless four-node quadrilateral element（FE-LSPIM QUAD4）, which is a hybrid FE-meshless method.Derivatives of Q4-CNS are continuous at nodes, so the continuous nodal stress can be obtained without any smoothing operation.It is found that,compared with the standard four-node quadrilateral element（QUAD4）,Q4- CNS can achieve significantly better accuracy and higher convergence rate.It is also found that Q4-CNS exhibits high tolerance to mesh distortion.Moreover,since derivatives of Q4-CNS shape functions are continuous at nodes,Q4-CNS is potentially useful for the problem of bending plate and shell models.展开更多
A novel polygonal finite element method （PFEM） based on partition of unity is proposed, termed the virtual node method （VNM）. To test the performance of the present method, numerical examples are given for solid m...A novel polygonal finite element method （PFEM） based on partition of unity is proposed, termed the virtual node method （VNM）. To test the performance of the present method, numerical examples are given for solid mechanics problems. With a polynomial form, the VNM achieves better results than those of traditional PFEMs, including the Wachspress method and the mean value method in standard patch tests. Compared with the standard triangular FEM, the VNM can achieve better accuracy. With the ability to construct shape functions on polygonal elements, the VNM provides greater flexibility in mesh generation. Therefore, several fracture problems are studied to demonstrate the potential implementation. With the advantage of the VNM, the convenient refinement and remeshing strategy are applied.展开更多
As a crucial fruit tree crop,the health and yield of apple trees are intricately linked to soil moisture conditions.This study aimed to integrate the enhanced WOFOST model with the HYDRUS model to simulate the growth ...As a crucial fruit tree crop,the health and yield of apple trees are intricately linked to soil moisture conditions.This study aimed to integrate the enhanced WOFOST model with the HYDRUS model to simulate the growth and development of apple trees,as well as the dynamics of soil moisture under varying degrees of water deficit.The outputs of evapotranspiration(ET0)and leaf area index(LAI)from the WOFOST model during the apple growth phase were specifically integrated with HYDRUS-1D.These parameters served as intermediaries to assess the impact of different water deficit scenarios on apple tree growth and soil moisture content.The experimental design included three levels of water deficit treatments in addition to control,with irrigation volumes for the deficit treatments set at 85%,70%,and 55%of the control’s volume,respectively.The model-predicted LAI across all irrigation treatments exhibited an R^(2) range of 0.89-0.95,a normalized root mean square error(NRMSE)between 8.02%and 14.57%,and yield prediction errors ranging from 6.27%to 9.61%,closely aligned with empirical data.The accuracy of simulated soil moisture content was enhanced in the 0-30 cm layer,with a slight decrease in accuracy observed in the 30-60 cm layer.For each irrigation treatment,the R^(2) values for simulated soil moisture content ranged from 0.77 to 0.89 in the 0-30 cm layer and from 0.75 to 0.81 in the 30-60 cm layer.This study validated the capability of the WOFOST-HYDRUS model to accurately simulate the effects of varied water deficit treatments on soil moisture,LAI,and apple tree yield,providing valuable insights for developing optimal irrigation strategies.展开更多
Soil moisture is a critical component of the soil-plant-atmosphere continuum(SPAC)in fruit trees.However,highprecision monitoring of orchard soil moisture at the regional scale still remains a challenge.This study pre...Soil moisture is a critical component of the soil-plant-atmosphere continuum(SPAC)in fruit trees.However,highprecision monitoring of orchard soil moisture at the regional scale still remains a challenge.This study presents a two-stage feature space model to estimate root zone soil moisture using UAV remote sensing data.The results indicate that the temperature-leaf area index(TLDI)is negatively correlated with soil water content.The upper triangular space performs highly effectively for deep soil moisture inversion,with R2 values ranging from 0.56 to 0.66,RMSE between 0.20 and 0.27,and RPD from 1.25 to 1.50.Conversely,the lower triangular space yields superior results for shallow soil moisture inversion,with R2 values between 0.67 and 0.82,RMSE from 0.15 to 0.19,and RPD between 1.67 and 2.09.The results suggest that the lower triangular space is optimal for shallow soil moisture inversion,while the upper triangular space is more suited for deep soil moisture inversion.This study presents a novel approach for estimating deep soil moisture in orchards,providing a theoretical basis for improving soil moisture management.展开更多
The semi-circular bend(SCB) dynamic fracture toughness test is simulated using discrete element models. The influence of the frictional boundary condition, constitutive law and specimen thickness on the test measureme...The semi-circular bend(SCB) dynamic fracture toughness test is simulated using discrete element models. The influence of the frictional boundary condition, constitutive law and specimen thickness on the test measurements is investigated. It is found that friction between loading plates and the rock specimen affects the test results. Therefore, friction must be carefully considered to obtain accurate measurements. The simulation results also show that in contrast to the 2D model in which a rate-dependent cohesive law must be introduced, 3D models with a rate-independent law can produce good results. Furthermore, the study suggests that test measurements are seriously affected by specimen thickness; thus, full 3D modeling is required for simulation of the SCB test.展开更多
With accumulating evidence of transcatheter aortic valve replacement(TAVR)worldwide,it is gradually realized that patients being treated are different across different coun-tries,including but not limited to their age...With accumulating evidence of transcatheter aortic valve replacement(TAVR)worldwide,it is gradually realized that patients being treated are different across different coun-tries,including but not limited to their age,habitus,disease etiology,aortic valve morphology,and sizes of structures.[1]In China,the average age of TAVR patients is around 5 years younger than industrialized countries,[2]making Chinese patients a good predictive sample of what the industrialized countries might see in TAVR screening in the near future due to the expansion of this technique to younger patients,but anatomical features appreciated from multi-slice computed tomography(MSCT)in the Chinese patient population have not been well demonstrated.展开更多
文摘Formulation and numerical evaluation of a novel four-node quadrilateral element with continuous nodal stress（Q4-CNS）are presented.Q4-CNS can be regarded as an improved hybrid FE-meshless four-node quadrilateral element（FE-LSPIM QUAD4）, which is a hybrid FE-meshless method.Derivatives of Q4-CNS are continuous at nodes, so the continuous nodal stress can be obtained without any smoothing operation.It is found that,compared with the standard four-node quadrilateral element（QUAD4）,Q4- CNS can achieve significantly better accuracy and higher convergence rate.It is also found that Q4-CNS exhibits high tolerance to mesh distortion.Moreover,since derivatives of Q4-CNS shape functions are continuous at nodes,Q4-CNS is potentially useful for the problem of bending plate and shell models.
文摘A novel polygonal finite element method （PFEM） based on partition of unity is proposed, termed the virtual node method （VNM）. To test the performance of the present method, numerical examples are given for solid mechanics problems. With a polynomial form, the VNM achieves better results than those of traditional PFEMs, including the Wachspress method and the mean value method in standard patch tests. Compared with the standard triangular FEM, the VNM can achieve better accuracy. With the ability to construct shape functions on polygonal elements, the VNM provides greater flexibility in mesh generation. Therefore, several fracture problems are studied to demonstrate the potential implementation. With the advantage of the VNM, the convenient refinement and remeshing strategy are applied.
基金financially supported by the National Natural Science Foundation of China(Grant No.52309050)the Key R&D and Promotion Projects in Henan Province(Science and Technology Development)(Grant No.232102110264)+1 种基金Youth Backbone Teacher Project of Henan University of Science and Technology(Grants No.13450013 and 13450010)the Key Scientific Research Projects of Colleges and Universities in Henan Province(Grant No.24B416001).
文摘As a crucial fruit tree crop,the health and yield of apple trees are intricately linked to soil moisture conditions.This study aimed to integrate the enhanced WOFOST model with the HYDRUS model to simulate the growth and development of apple trees,as well as the dynamics of soil moisture under varying degrees of water deficit.The outputs of evapotranspiration(ET0)and leaf area index(LAI)from the WOFOST model during the apple growth phase were specifically integrated with HYDRUS-1D.These parameters served as intermediaries to assess the impact of different water deficit scenarios on apple tree growth and soil moisture content.The experimental design included three levels of water deficit treatments in addition to control,with irrigation volumes for the deficit treatments set at 85%,70%,and 55%of the control’s volume,respectively.The model-predicted LAI across all irrigation treatments exhibited an R^(2) range of 0.89-0.95,a normalized root mean square error(NRMSE)between 8.02%and 14.57%,and yield prediction errors ranging from 6.27%to 9.61%,closely aligned with empirical data.The accuracy of simulated soil moisture content was enhanced in the 0-30 cm layer,with a slight decrease in accuracy observed in the 30-60 cm layer.For each irrigation treatment,the R^(2) values for simulated soil moisture content ranged from 0.77 to 0.89 in the 0-30 cm layer and from 0.75 to 0.81 in the 30-60 cm layer.This study validated the capability of the WOFOST-HYDRUS model to accurately simulate the effects of varied water deficit treatments on soil moisture,LAI,and apple tree yield,providing valuable insights for developing optimal irrigation strategies.
基金supported by the National Natural Science Foundation of China(Grant No.52309050)Key R&D and Promotion Projects in Henan Province(Science and Technology Development)(Grant No.232102110264)+2 种基金Key Scientific Research Projects of Colleges and Universities in Henan Province(Grant No.24B416001)Youth Backbone Teacher Project of Henan University of Science and Technology(Grants No.13450013 and 13450010)Sichuan Province Science and Technology Support Projects(Grants No.2023YFQ0025,2024YFHZ0217,2024ZHCG0101,2024YFHZ0200).
文摘Soil moisture is a critical component of the soil-plant-atmosphere continuum(SPAC)in fruit trees.However,highprecision monitoring of orchard soil moisture at the regional scale still remains a challenge.This study presents a two-stage feature space model to estimate root zone soil moisture using UAV remote sensing data.The results indicate that the temperature-leaf area index(TLDI)is negatively correlated with soil water content.The upper triangular space performs highly effectively for deep soil moisture inversion,with R2 values ranging from 0.56 to 0.66,RMSE between 0.20 and 0.27,and RPD from 1.25 to 1.50.Conversely,the lower triangular space yields superior results for shallow soil moisture inversion,with R2 values between 0.67 and 0.82,RMSE from 0.15 to 0.19,and RPD between 1.67 and 2.09.The results suggest that the lower triangular space is optimal for shallow soil moisture inversion,while the upper triangular space is more suited for deep soil moisture inversion.This study presents a novel approach for estimating deep soil moisture in orchards,providing a theoretical basis for improving soil moisture management.
基金supported by the Australian Research Council(Grant No.DE130100457)State Key Laboratory of Hydraulics and Mountain River Engineering(SKHL)(Grant No.SKHL1407)the National Natural Science Foundation of China(Grant Nos.41202207,51204112 and 2015JY0045)
文摘The semi-circular bend(SCB) dynamic fracture toughness test is simulated using discrete element models. The influence of the frictional boundary condition, constitutive law and specimen thickness on the test measurements is investigated. It is found that friction between loading plates and the rock specimen affects the test results. Therefore, friction must be carefully considered to obtain accurate measurements. The simulation results also show that in contrast to the 2D model in which a rate-dependent cohesive law must be introduced, 3D models with a rate-independent law can produce good results. Furthermore, the study suggests that test measurements are seriously affected by specimen thickness; thus, full 3D modeling is required for simulation of the SCB test.
基金the National Natural Science Foundation of China(No.81970325 and No.82102129)Open Fund Research from State Key Laboratory of Hydraulics and Mountain River Engineering(No.SKHL1920).
文摘With accumulating evidence of transcatheter aortic valve replacement(TAVR)worldwide,it is gradually realized that patients being treated are different across different coun-tries,including but not limited to their age,habitus,disease etiology,aortic valve morphology,and sizes of structures.[1]In China,the average age of TAVR patients is around 5 years younger than industrialized countries,[2]making Chinese patients a good predictive sample of what the industrialized countries might see in TAVR screening in the near future due to the expansion of this technique to younger patients,but anatomical features appreciated from multi-slice computed tomography(MSCT)in the Chinese patient population have not been well demonstrated.
