Background:The burden of common urologic diseases,including benign prostatic hyperplasia(BPH),urinary tract infections(UTI),urolithiasis,bladder cancer,kidney cancer,and prostate cancer,varies both geographically and ...Background:The burden of common urologic diseases,including benign prostatic hyperplasia(BPH),urinary tract infections(UTI),urolithiasis,bladder cancer,kidney cancer,and prostate cancer,varies both geographically and within specific regions.It is essential to conduct a comprehensive and precise assessment of the global burden of urologic diseases.Methods:We obtained data on incidence,prevalence,mortality,and disability-adjusted life-years(DALYs)for the aforementioned urologic diseases by age,sex,location,and year from the Global Burden of Disease(GBD)2021.We analyzed the burden associated with urologic diseases based on socio-demographic index(SDI)and attributable risk factors.The trends in burden over time were assessed using estimated annual percentage changes(EAPC)along with a 95%confidence interval(CI).Results:In 2021,BPH and UTI were the leading causes of age-standardized incidence rate(ASIR)and age-standardized prevalence rate(ASPR),with rates of 5531.88 and 2782.59 per 100,000 persons,respectively.Prostate cancer was the leading cause of both age-standardized mortality rate(ASMR)and age-standardized DALYs rate(ASDR),with rates of 12.63 and 217.83 per 100,000 persons,respectively.From 1990 to 2021,there was an upward trend in ASIR,ASPR,ASMR,and ASDR for UTI,while urolithiasis showed a downward trend.The middle and low-middle SDI quintile levels exhibited higher incidence,prevalence,mortality,and DALYs related to UTI,urolithiasis,and BPH,while the high and high-middle SDI quintile levels showed higher rates for the three cancers.The burden of these 6 urologic diseases displayed diverse age and sex distribution patterns.In 2021,a high body mass index(BMI)contributed to 20.07%of kidney cancer deaths worldwide,while smoking accounted for 26.48%of bladder cancer deaths and 3.00%of prostate cancer deaths.Conclusions:The global burden of 6 urologic diseases presents a significant public health challenge.Urgent international collaboration is essential to advance the improvement of urologic disease management,encompassing the development of effective diagnostic screening tools and the implementation of high-quality prevention and treatment strategies.展开更多
With the rapid development of the Internet of Things,there is a great demand for portable gas sensors.Metal oxide semiconductors(MOS)are one of the most traditional and well-studied gas sensing materials and have been...With the rapid development of the Internet of Things,there is a great demand for portable gas sensors.Metal oxide semiconductors(MOS)are one of the most traditional and well-studied gas sensing materials and have been widely used to prepare various commercial gas sensors.However,it is limited by high operating temperature.The current research works are directed towards fabricating high-performance flexible room-temperature(FRT)gas sensors,which are effective in simplifying the structure of MOS-based sensors,reducing power consumption,and expanding the application of portable devices.This article presents the recent research progress of MOS-based FRT gas sensors in terms of sensing mechanism,performance,flexibility characteristics,and applications.This review comprehensively summarizes and discusses five types of MOS-based FRT gas sensors,including pristine MOS,noble metal nanoparticles modified MOS,organic polymers modified MOS,carbon-based materials(carbon nanotubes and graphene derivatives)modified MOS,and two-dimensional transition metal dichalcogenides materials modified MOS.The effect of light-illuminated to improve gas sensing performance is further discussed.Furthermore,the applications and future perspectives of FRT gas sensors are also discussed.展开更多
The random displacement model(RDM)can efficiently simulate particle transport processes,which are difficult to observe,incorporating stochastic and hydraulic parameters.In recent decades,it has been used in many domai...The random displacement model(RDM)can efficiently simulate particle transport processes,which are difficult to observe,incorporating stochastic and hydraulic parameters.In recent decades,it has been used in many domains,including environments,hydraulics,and ecology.However,the results exhibit significant uncertainties arising from the model resolution,hydrodynamic accuracy,intrinsic characteristics of particles,and boundary conditions.The objective of the present study is to comprehensively interpret the RDM from theory to application,and emphasize essential considerations for users in different domains.The study also provides several application strategies for the model,based on several practical RDM cases.Determining the turbulent diffusivity and velocity profiles in complex flow field is a critical step to precisely simulate particle movement.Furthermore,the physical and biological properties of passive and active particles require fundamental investigation to extend the applicability of the model.Existing studies suggest that flexibly coupling the RDM with other numerical models customized to the characteristics of distinct problems will substantially expand the utility of the RDM and could yield innovative approaches for addressing previously intractable issues.展开更多
The significance of riparian vegetation on river flow and material transport is not in dispute.Conveyance laws,sediment erosion and deposition,and element cycling must all be adjusted from their canonical rough-wall b...The significance of riparian vegetation on river flow and material transport is not in dispute.Conveyance laws,sediment erosion and deposition,and element cycling must all be adjusted from their canonical rough-wall boundary layer to accommodate the presence of aquatic plants.In turn,the growth and colonization of riparian vegetation are affected by fluvial processes and river morphology on longer time scales.These interactions and feedbacks at multiple time scales are now drawing significant attention within the research community given their relevance to river restoration.For this reason,a review summarizing methods,general laws,qualitative cognition,and quantitative models regarding the interplay between aquatic plants,flow dynamics,and sediment transport in vegetated rivers is in order.Shortcomings,pitfalls,knowledge gaps,and daunting challenges to the current state of knowledge are also covered.As a multidisciplinary research topic,a future research agenda and opportunities pertinent to river management and enhancement of ecosystem services are also highlighted.展开更多
Background:Tuberculosis(TB)is still one of the most serious infectious diseases in the mainland of China.So it was urgent for the formulation of more effective measures to prevent and control it.Methods:The data of re...Background:Tuberculosis(TB)is still one of the most serious infectious diseases in the mainland of China.So it was urgent for the formulation of more effective measures to prevent and control it.Methods:The data of reported TB cases in 340 prefectures from the mainland of China were extracted from the China Information System for Disease Control and Prevention(CISDCP)during January 2005 to December 2015.The Kulldorff’s retrospective space-time scan statistics was used to identify the temporal,spatial and spatio-temporal clusters of reported TB in the mainland of China by using the discrete Poisson probability model.Spatio-temporal clusters of sputum smear-positive(SS+)reported TB and sputum smearnegative(SS-)reported TB were also detected at the prefecture level.Results:A total of 10200528 reported TB cases were collected from 2005 to 2015 in 340 prefectures,including 5283983 SS-TB cases and 4631734 SS+TB cases with specific sputum smear results,284811 cases without sputum smear test.Significantly TB clustering patterns in spatial,temporal and spatiotemporal were observed in this research.Results of the Kulldorff’s scan found twelve significant space-time clusters of reported TB.The most likely spatio-temporal cluster(RR=3.27,P<0.001)was mainly located in Xinjiang Uygur Autonomous Region of western China,covering five prefectures and clustering in the time frame from September 2012 to November 2015.The spatio-temporal clustering results of SS+TB and SS-TB also showed the most likely clusters distributed in the western China.However,the clustering time of SS+TB was concentrated before 2010 while SS-TB was mainly concentrated after 2010.Conclusions:This study identified the time and region of TB,SS+TB and SS-TB clustered easily in 340 prefectures in the mainland of China,which is helpful in prioritizing resource assignment in high-risk periods and high-risk areas,and to formulate powerful strategy to prevention and control TB.展开更多
Floating vegetation island(FVI)provides an effective way to remove excessive nutrition and pollutants in rivers.The Reynolds stress model(RSM)is employed to investigate the hydrodynamic characteristics induced by vari...Floating vegetation island(FVI)provides an effective way to remove excessive nutrition and pollutants in rivers.The Reynolds stress model(RSM)is employed to investigate the hydrodynamic characteristics induced by varied canopy densities of FVI in an open channel.In longitudinal direction,four regions are subdivided according to the flow development process:upstream adjustment region(LUD),diverging flow region(LDF),shear layer growth region(LSD),and flilly developed region.The increasing canopy density accelerates the flow adjustment in the diverging flow region and shear layer growth region,signaling a shorter distance to reach an equilibrium stage,while LUD keeps a constant.The vertical profiles of the normalized velocity are found to be self-similar downstream of the diverging flow region.In the vertical direction,the streamwise velocity profiles in the mixing layer collapse for all densities and obey the hyperbolic tangent law.Normalized penetration depth into the canopy was fitted as a function of dimensionless canopy density given by δc/hc=0.404(CDahc)^-0.316.This finding indicates a large space for rapid water renewal between the canopy region and the underlying water driven by the shear-scale vortices.In the lateral direction,the intensification of secondary current and the increasing number of secondary current cells with increasing canopy density reveal that dense floating canopies contribute to strong momentum exchange.The centers of vortices move as canopy density increases,while the vortices in canopy region do not merge with those in the gap region,as limited by the height and width of the canopy region.The distribution of longitudinal velocity in the transects is significantly influenced by secondary current.展开更多
Deep ultraviolet(DUV)phototransistors are key integral of optoelectronics bearing a wide spectrum of applications in flame sensor,military detector,oil spill detection,biological sensor,and artificial intelligence fie...Deep ultraviolet(DUV)phototransistors are key integral of optoelectronics bearing a wide spectrum of applications in flame sensor,military detector,oil spill detection,biological sensor,and artificial intelligence fields.In order to further improve the responsivity of UV photodetectors based onβ-Ga_(2)O_(3),in present work,high-performanceβ-Ga_(2)O_(3) phototransistors with local back-gate structure were experimentally demonstrated.The phototransistor shows excellent DUV photoelectrical performance with a high responsivity of 1.01×107 A/W,a high external quantum efficiency of 5.02×109%,a sensitive detectivity of 2.98×1015 Jones,and a fast rise time of 0.2 s under 250 nm illumination.Besides,first-principles calculations reveal the decent stability ofβGa_(2)O_(3) nanosheet against oxidation and humidity without significant performance degradations.Additionally,the hexagonal boron nitride(h-BN)/β-Ga_(2)O_(3) phototransistor can behave as a photonic synapse with ultralow power consumption of~9.6 fJ per spike,which shows its potential for neuromorphic computing tasks such as facial recognition.Thisβ-Ga_(2)O_(3) phototransistor will provide a perspective for the next generation optoelectrical systems.展开更多
Accurate estimation of the drag forces generated by vegetation stems is crucial for the comprehensive assessment of the impact of aquatic vegetation on hydrodynamic processes in aquatic environments.The coupling relat...Accurate estimation of the drag forces generated by vegetation stems is crucial for the comprehensive assessment of the impact of aquatic vegetation on hydrodynamic processes in aquatic environments.The coupling relationship between vegetation layer flow velocity and vegetation drag makes precise prediction of submerged vegetation drag forces particularly challenging.The present study utilized published data on submerged vegetation drag force measurements and employed a genetic programming(GP)algorithm,a machine learning technique,to establish the connection between submerged vegetation drag forces and flow and vegetation parameters.When using the bulk velocity,U,as the reference velocity scale to define the drag coefficient,C_(d),and stem Reynolds number,the GP runs revealed that the drag coefficient of submerged vegetation is related to submergence ratio(H^(*)),aspect ratio(d^(*)),blockage ratio(ψ^(*)),and vegetation density(λ).The relation between vegetation stem drag forces and flow velocity is implicitly embedded in the definition of C_(d).Comparisons with experimental drag force measurements indicate that using the bulk velocity as the reference velocity,as opposed to using the vegetation layer average velocity,U_(v),eliminates the need for complex iterative processes to estimate U_(v)and avoids introducing additional errors associated with U_(v)estimation.This approach significantly enhances the model’s predictive capabilities and results in a simpler and more user-friendly formula expression.展开更多
In simulating vegetated flows using the porous approach,the reasonableness of the drag coefficient significantly impacts the calculation results.This study employs large eddy simulation(LES)to quantitatively investiga...In simulating vegetated flows using the porous approach,the reasonableness of the drag coefficient significantly impacts the calculation results.This study employs large eddy simulation(LES)to quantitatively investigate the effect of drag parameters on key flow characteristics in submerged vegetated flows.The results indicate that changes in the drag coefficient significantly alter the velocity in the middle of the vegetation layer and near the water surface in the free-flow layer.Compared with longitudinal velocity,the drag coefficient has a more pronounced effect on the vertical distribution of Reynolds stress,especially its peak at the top of the vegetation layer.The porous approach can accurately reproduce the vertical distribution of longitudinal velocity and Reynolds stress,consistent with experimental measurements,only when shear-scale flow dominates.Due to the high-intensity secondary flow under moderate vegetation density,fluctuations in the drag coefficient have a more significant impact on the numerical results than in very dense vegetation.Therefore,selecting the drag coefficient value should be done cautiously,especially in the absence of experimental measurements for validation.展开更多
基金supported(in part)by the National Key Research and Development Program(2022YFC3600700)the Fundamental Research Funds for the Central Universities(2042024YXA008)the Young Top-Notch Talent Cultivation Program of Hubei Province(for Prof.Xian-Tao Zeng).
文摘Background:The burden of common urologic diseases,including benign prostatic hyperplasia(BPH),urinary tract infections(UTI),urolithiasis,bladder cancer,kidney cancer,and prostate cancer,varies both geographically and within specific regions.It is essential to conduct a comprehensive and precise assessment of the global burden of urologic diseases.Methods:We obtained data on incidence,prevalence,mortality,and disability-adjusted life-years(DALYs)for the aforementioned urologic diseases by age,sex,location,and year from the Global Burden of Disease(GBD)2021.We analyzed the burden associated with urologic diseases based on socio-demographic index(SDI)and attributable risk factors.The trends in burden over time were assessed using estimated annual percentage changes(EAPC)along with a 95%confidence interval(CI).Results:In 2021,BPH and UTI were the leading causes of age-standardized incidence rate(ASIR)and age-standardized prevalence rate(ASPR),with rates of 5531.88 and 2782.59 per 100,000 persons,respectively.Prostate cancer was the leading cause of both age-standardized mortality rate(ASMR)and age-standardized DALYs rate(ASDR),with rates of 12.63 and 217.83 per 100,000 persons,respectively.From 1990 to 2021,there was an upward trend in ASIR,ASPR,ASMR,and ASDR for UTI,while urolithiasis showed a downward trend.The middle and low-middle SDI quintile levels exhibited higher incidence,prevalence,mortality,and DALYs related to UTI,urolithiasis,and BPH,while the high and high-middle SDI quintile levels showed higher rates for the three cancers.The burden of these 6 urologic diseases displayed diverse age and sex distribution patterns.In 2021,a high body mass index(BMI)contributed to 20.07%of kidney cancer deaths worldwide,while smoking accounted for 26.48%of bladder cancer deaths and 3.00%of prostate cancer deaths.Conclusions:The global burden of 6 urologic diseases presents a significant public health challenge.Urgent international collaboration is essential to advance the improvement of urologic disease management,encompassing the development of effective diagnostic screening tools and the implementation of high-quality prevention and treatment strategies.
基金This work is supported by This work was supported by the National Key R&D Program of China(Nos.2020YFB2008604 and 2021YFB3202500)the National Natural Science Foundation of China(Nos.61874034 and 51861135105)+1 种基金the International Science and Technology Cooperation Program of Shanghai Science and Technology Innovation Action Plan(No.21520713300)Fudan University-CIOMP Joint Fund(E02632Y7H0).
文摘With the rapid development of the Internet of Things,there is a great demand for portable gas sensors.Metal oxide semiconductors(MOS)are one of the most traditional and well-studied gas sensing materials and have been widely used to prepare various commercial gas sensors.However,it is limited by high operating temperature.The current research works are directed towards fabricating high-performance flexible room-temperature(FRT)gas sensors,which are effective in simplifying the structure of MOS-based sensors,reducing power consumption,and expanding the application of portable devices.This article presents the recent research progress of MOS-based FRT gas sensors in terms of sensing mechanism,performance,flexibility characteristics,and applications.This review comprehensively summarizes and discusses five types of MOS-based FRT gas sensors,including pristine MOS,noble metal nanoparticles modified MOS,organic polymers modified MOS,carbon-based materials(carbon nanotubes and graphene derivatives)modified MOS,and two-dimensional transition metal dichalcogenides materials modified MOS.The effect of light-illuminated to improve gas sensing performance is further discussed.Furthermore,the applications and future perspectives of FRT gas sensors are also discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12402493,U2340216,52020105006 and 12272281)supported by the China Postdoctoral Science Foundation(Grant Nos.2024M752476,2025T180862)the Postdoctoral Project of Hubei Province(Grant No.2024HBBHCXA060).
文摘The random displacement model(RDM)can efficiently simulate particle transport processes,which are difficult to observe,incorporating stochastic and hydraulic parameters.In recent decades,it has been used in many domains,including environments,hydraulics,and ecology.However,the results exhibit significant uncertainties arising from the model resolution,hydrodynamic accuracy,intrinsic characteristics of particles,and boundary conditions.The objective of the present study is to comprehensively interpret the RDM from theory to application,and emphasize essential considerations for users in different domains.The study also provides several application strategies for the model,based on several practical RDM cases.Determining the turbulent diffusivity and velocity profiles in complex flow field is a critical step to precisely simulate particle movement.Furthermore,the physical and biological properties of passive and active particles require fundamental investigation to extend the applicability of the model.Existing studies suggest that flexibly coupling the RDM with other numerical models customized to the characteristics of distinct problems will substantially expand the utility of the RDM and could yield innovative approaches for addressing previously intractable issues.
基金Projects supported by the National Natural Science Foundation of China(Grant Nos.52020105006,11872285)the U.S.National Science Foundation(Grant Nos.NSF-AGS-1644382,NSF-AGS-2028633 and NSF-IOS-1754893).
文摘The significance of riparian vegetation on river flow and material transport is not in dispute.Conveyance laws,sediment erosion and deposition,and element cycling must all be adjusted from their canonical rough-wall boundary layer to accommodate the presence of aquatic plants.In turn,the growth and colonization of riparian vegetation are affected by fluvial processes and river morphology on longer time scales.These interactions and feedbacks at multiple time scales are now drawing significant attention within the research community given their relevance to river restoration.For this reason,a review summarizing methods,general laws,qualitative cognition,and quantitative models regarding the interplay between aquatic plants,flow dynamics,and sediment transport in vegetated rivers is in order.Shortcomings,pitfalls,knowledge gaps,and daunting challenges to the current state of knowledge are also covered.As a multidisciplinary research topic,a future research agenda and opportunities pertinent to river management and enhancement of ecosystem services are also highlighted.
基金The research was supported by the National S&T Major Project(Grant No.2014ZX10004005–001).
文摘Background:Tuberculosis(TB)is still one of the most serious infectious diseases in the mainland of China.So it was urgent for the formulation of more effective measures to prevent and control it.Methods:The data of reported TB cases in 340 prefectures from the mainland of China were extracted from the China Information System for Disease Control and Prevention(CISDCP)during January 2005 to December 2015.The Kulldorff’s retrospective space-time scan statistics was used to identify the temporal,spatial and spatio-temporal clusters of reported TB in the mainland of China by using the discrete Poisson probability model.Spatio-temporal clusters of sputum smear-positive(SS+)reported TB and sputum smearnegative(SS-)reported TB were also detected at the prefecture level.Results:A total of 10200528 reported TB cases were collected from 2005 to 2015 in 340 prefectures,including 5283983 SS-TB cases and 4631734 SS+TB cases with specific sputum smear results,284811 cases without sputum smear test.Significantly TB clustering patterns in spatial,temporal and spatiotemporal were observed in this research.Results of the Kulldorff’s scan found twelve significant space-time clusters of reported TB.The most likely spatio-temporal cluster(RR=3.27,P<0.001)was mainly located in Xinjiang Uygur Autonomous Region of western China,covering five prefectures and clustering in the time frame from September 2012 to November 2015.The spatio-temporal clustering results of SS+TB and SS-TB also showed the most likely clusters distributed in the western China.However,the clustering time of SS+TB was concentrated before 2010 while SS-TB was mainly concentrated after 2010.Conclusions:This study identified the time and region of TB,SS+TB and SS-TB clustered easily in 340 prefectures in the mainland of China,which is helpful in prioritizing resource assignment in high-risk periods and high-risk areas,and to formulate powerful strategy to prevention and control TB.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11872285,11672213).
文摘Floating vegetation island(FVI)provides an effective way to remove excessive nutrition and pollutants in rivers.The Reynolds stress model(RSM)is employed to investigate the hydrodynamic characteristics induced by varied canopy densities of FVI in an open channel.In longitudinal direction,four regions are subdivided according to the flow development process:upstream adjustment region(LUD),diverging flow region(LDF),shear layer growth region(LSD),and flilly developed region.The increasing canopy density accelerates the flow adjustment in the diverging flow region and shear layer growth region,signaling a shorter distance to reach an equilibrium stage,while LUD keeps a constant.The vertical profiles of the normalized velocity are found to be self-similar downstream of the diverging flow region.In the vertical direction,the streamwise velocity profiles in the mixing layer collapse for all densities and obey the hyperbolic tangent law.Normalized penetration depth into the canopy was fitted as a function of dimensionless canopy density given by δc/hc=0.404(CDahc)^-0.316.This finding indicates a large space for rapid water renewal between the canopy region and the underlying water driven by the shear-scale vortices.In the lateral direction,the intensification of secondary current and the increasing number of secondary current cells with increasing canopy density reveal that dense floating canopies contribute to strong momentum exchange.The centers of vortices move as canopy density increases,while the vortices in canopy region do not merge with those in the gap region,as limited by the height and width of the canopy region.The distribution of longitudinal velocity in the transects is significantly influenced by secondary current.
基金supported by the National Natural Science Foundation of China(Nos.62027818,61874034,51861135105,and 51972319)International Science and Technology Cooperation Program of Shanghai Science and Technology Innovation Action Plan(No.21520713300)Science and Technology Commission of Shanghai Municipality(No.19520744400).
文摘Deep ultraviolet(DUV)phototransistors are key integral of optoelectronics bearing a wide spectrum of applications in flame sensor,military detector,oil spill detection,biological sensor,and artificial intelligence fields.In order to further improve the responsivity of UV photodetectors based onβ-Ga_(2)O_(3),in present work,high-performanceβ-Ga_(2)O_(3) phototransistors with local back-gate structure were experimentally demonstrated.The phototransistor shows excellent DUV photoelectrical performance with a high responsivity of 1.01×107 A/W,a high external quantum efficiency of 5.02×109%,a sensitive detectivity of 2.98×1015 Jones,and a fast rise time of 0.2 s under 250 nm illumination.Besides,first-principles calculations reveal the decent stability ofβGa_(2)O_(3) nanosheet against oxidation and humidity without significant performance degradations.Additionally,the hexagonal boron nitride(h-BN)/β-Ga_(2)O_(3) phototransistor can behave as a photonic synapse with ultralow power consumption of~9.6 fJ per spike,which shows its potential for neuromorphic computing tasks such as facial recognition.Thisβ-Ga_(2)O_(3) phototransistor will provide a perspective for the next generation optoelectrical systems.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC3202601)the National Natural Science Foundation of China(Grant No.52309088)+1 种基金the China Postdoctoral Science Foundation(Grant No.2023M730932)the Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2023ZB608).
文摘Accurate estimation of the drag forces generated by vegetation stems is crucial for the comprehensive assessment of the impact of aquatic vegetation on hydrodynamic processes in aquatic environments.The coupling relationship between vegetation layer flow velocity and vegetation drag makes precise prediction of submerged vegetation drag forces particularly challenging.The present study utilized published data on submerged vegetation drag force measurements and employed a genetic programming(GP)algorithm,a machine learning technique,to establish the connection between submerged vegetation drag forces and flow and vegetation parameters.When using the bulk velocity,U,as the reference velocity scale to define the drag coefficient,C_(d),and stem Reynolds number,the GP runs revealed that the drag coefficient of submerged vegetation is related to submergence ratio(H^(*)),aspect ratio(d^(*)),blockage ratio(ψ^(*)),and vegetation density(λ).The relation between vegetation stem drag forces and flow velocity is implicitly embedded in the definition of C_(d).Comparisons with experimental drag force measurements indicate that using the bulk velocity as the reference velocity,as opposed to using the vegetation layer average velocity,U_(v),eliminates the need for complex iterative processes to estimate U_(v)and avoids introducing additional errors associated with U_(v)estimation.This approach significantly enhances the model’s predictive capabilities and results in a simpler and more user-friendly formula expression.
基金Projects supported by the National Natural Science Foundation of China(Grant No.52309088).
文摘In simulating vegetated flows using the porous approach,the reasonableness of the drag coefficient significantly impacts the calculation results.This study employs large eddy simulation(LES)to quantitatively investigate the effect of drag parameters on key flow characteristics in submerged vegetated flows.The results indicate that changes in the drag coefficient significantly alter the velocity in the middle of the vegetation layer and near the water surface in the free-flow layer.Compared with longitudinal velocity,the drag coefficient has a more pronounced effect on the vertical distribution of Reynolds stress,especially its peak at the top of the vegetation layer.The porous approach can accurately reproduce the vertical distribution of longitudinal velocity and Reynolds stress,consistent with experimental measurements,only when shear-scale flow dominates.Due to the high-intensity secondary flow under moderate vegetation density,fluctuations in the drag coefficient have a more significant impact on the numerical results than in very dense vegetation.Therefore,selecting the drag coefficient value should be done cautiously,especially in the absence of experimental measurements for validation.
