检索结果-南通市图书馆

Predicting submerged vegetation drag with a machine learning-based method

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2024年第3期36卷 534-545页

作者： Meng-yang Liu Hong-wu Tang Sai-yu Yuan Jing Yan College of water Conservancy and hydropower engineering Hohai UniversityNanjing210098China Key Laboratory of Hydrologic-Cycle and Hydrodynamic-System of Ministry of water resources Hohai UniversityNanjing210098China

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 *** coupling relationship between vegetation layer flow velocity and vegetation drag makes precise prediction of submerged vegetation drag forces particularly *** 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 *** 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)*** approach significantly enhances the model’s predictive capabilities and results in a simpler and more user-friendly formula expression.

关键词： Drag coefficient genetic programming algorithm submerged vegetation flow resistance cylinder array

Pixel-level crack segmentation of tunnel lining segments based on an encoder–decoder network

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil engineering 2024年第5期18卷 681-698页

作者： Shaokang HOU Zhigang OU Yuequn HUANG Yaoru LIU State Key Laboratory of Hydroscience and engineering Tsinghua UniversityBeijing 100084China China Renewable Energy engineering institute Beijing 100120China State Key Laboratory of Stimulation and Regulation of water Cycles in River Basins China Institute of Water Resources and Hydropower ResearchBeijing 100038China Hunan Provincial water resources Development&Investment Co. Ltd.Changsha 410007China

Regular detection and repair for lining cracks are necessary to guarantee the safety and stability of *** development of computer vision has greatly promoted structural health *** study proposes a novel encoder–decoder structure,CrackRecNet,for semantic segmentation of lining segment cracks by integrating improved VGG-19 into the U-Net *** image acquisition equipment is designed based on a camera,3-dimensional printing(3DP)bracket and two laser rangefinders.A tunnel concrete structure crack(TCSC)image data set,containing images collected from a double-shield tunnel boring machines(TBM)tunnel in China,was *** data preprocessing operations,such as brightness adjustment,pixel resolution adjustment,flipping,splitting and annotation,2880 image samples with pixel resolution of 448×448 were *** model was implemented by Pytorch in PyCharm processed with 4 NVIDIA TITAN V *** the experiments,the proposed CrackRecNet showed better prediction performance than U-Net,TernausNet,and *** paper also discusses GPU parallel acceleration effect and the crack maximum width quantification.

关键词： tunnel lining segment crack detection semantic segmentation convolutional neural network encoder-decoder structure

What control the spatial patterns and predictions of runoff response over the contiguous USA?

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2024年第7期34卷 1297-1322页

作者： JIANG Shanhu DU Shuping REN Liliang GONG Xinglong YAN Denghua YUAN Shanshui LIU Yi YANG Xiaoli XU Chongyu The National Key Laboratory of water Disaster Prevention Hohai UniversityNanjing210098China College of Hydrology and water resources Hohai UniversityNanjing210098China School of water Conservancy&Civil engineering Northeast Agricultural UniversityHarbin150030China Department of water resources China Institute of Water Resources and Hydropower ResearchBeijing100038China Department of Geosciences University of OsloOsloNorway

Understanding the nonlinear relationship between hydrological response and key factors and the cause behind this relationship is vital for water resource management and earth system *** this study,we undertook several steps to explore the ***,we partitioned runoff response change(RRC)into multiple components associated with climate and catchment properties,and examined the spatial patterns and smoothness indicated by the Moran's Index of RRC across the contiguous United States(CONUS).Subsequently,we employed a machine learning model to predict RRC using catchment attribute predictors encompassing climate,topography,hydrology,soil,land use/cover,and ***,we identified the primary factors influencing RRC and quantified how these key factors control RRC by employing the accumulated local effect,which allows for the representation of not only dominant but also secondary ***,we explored the relationship between ecoregion patterns,climate gradients,and the distribution of RRC across *** findings indicate that:(1)RRC demonstrating significant connections between catchments tends to be well predicted by catchment attributes in space;(2)climate,hydrology,and topography emerge as the top three key attributes nonlinearly influencing the RRC patterns,with their second-order effects determining the heterogeneous patterns of RRC;and(3)local Moran's I signifies a collaborative relationship between the patterns of RRC and their spatial smoothness,climate space,and ecoregions.

关键词： hydrological response prediction machine learning accumulated local effect Moran’s Index large-sample study

Effectiveness of urban distributed runoff model for discharge and water depth calculation in urban drainage pipe networks

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2024年第3期36卷 582-591页

作者： Yang Zhou Yi-ling Leng Peng-yu Wang Shang-hong Zhang Yu-long Zhu Yu-jun Yi School of water resources and hydropower engineering North China Electric Power UniversityBeijing102206China State Key Laboratory of water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing100875China

Effective urban land-use re-planning and the strategic arrangement of drainage pipe networks can significantly enhance urban flood defense *** at reducing the potential risks of urban flooding,this paper presents a straightforward and efficient approach to an urban distributed runoff model(UDRM).The model is developed to quantify the discharge and water depth within urban drainage pipe networks under varying rainfall intensities and land-use *** Nash efficiency coefficient of UDRM exceeds 0.9,which indicates its high computational efficiency and potential benefit in predicting urban *** prediction of drainage conditions under both current and re-planned land-use types is achieved by adopting different flood recurrence *** findings reveal that the re-planned land-use strategies could effectively diminish flood risk upstream of the drainage pipe network across 20-year and 50-year flood recurrence ***,in the case of extreme rainfall events(a 100-year flood recurrence),the re-planned land-use approach fell short of fulfilling the requirements necessary for flood disaster *** these instances,the adoption of larger-diameter drainage pipes becomes an essential requisite to satisfy drainage ***,the proposed UDRM effectively combines land-use information with pipeline data to give practical suggestions for pipeline modification and land-use optimization to combat urban ***,this methodology warrants further promotion in the field of urban re-planning.

关键词： Stormwater runoff water depth urban distributed runoff model urban drainage pipe networks urban land-use re-planning

Analytical solutions of turbulent boundary layer beneath forward-leaning waves

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 695-710页

作者： Yiqin XIE Jifu ZHOU Xu WANG Jinlong DUAN Yongjun LU Shouqian LI Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Simulation and Regulation of water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China School of engineering Sciences University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Hydrology-water resources and Hydraulic engineering Nanjing Hydraulic Research InstituteNanjing 210024China

As a typical nonlinear wave,forward-leaning waves can be frequently encountered in the near-shore areas,which can impact coastal sediment transport ***,it is of significance to describe the characteristics of the boundary layer beneath forward-leaning waves accurately,especially for the turbulent boundary *** this work,the linearized turbulent boundary layer model with a linear turbulent viscosity coefficient is applied,and the novel expression of the near-bed orbital velocity that has been worked out by the authors for forward-leaning waves of arbitrary forward-leaning degrees is further used to specify the free stream boundary condition of the bottom boundary ***,a variable transformation is found so as to make the equation of the turbulent boundary layer model be solved analytically through a modified Bessel ***,an explicit analytical solution of the turbulent boundary layer beneath forward-leaning waves is derived by means of variable separation and variable *** analytical solutions of the velocity profile and bottom shear stress of the turbulent boundary layer beneath forward-leaning waves are verified by comparing the present analytical results with typical experimental data available in the previous literature.

关键词： forward-leaning wave turbulent boundary layer velocity profile bottom shear stress

Blast damage zone strength reduction method for deep cavern excavation and its application

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil engineering 2024年第2期18卷 236-251页

作者： Tianzhi YAO Zuguo MO Li QIAN Yunpeng GAO Jianhai ZHANG Xianglin XING Enlong LIU Ru ZHANG State Key Laboratory of Hydraulics and Mountain River engineering College of Water Resources and HydropowerSichuan UniversityChengdu 610065China Power China Chengdu engineering Corporation Limited Chengdu 610072China

The drill and blast(D&B)method is widely used to excavate underground spaces,but explosions generally cause damage to the ***,no blast simulation method can provide computational accuracy and *** this paper,a blast equivalent simulation method called the blast damage zone strength reduction(BDZSR)method is *** method first calculates the range of the blast-induced damage zone(BDZ)by formulae,then reduces the strength and deformation parameters of the rock within the BDZ ahead of excavation,and finally calculates the excavation damage zone(EDZ)for the D&B method by numerical *** method combines stress wave attenuation,rock damage criteria and stress path variation to derive the BDZ depth calculation *** formulae consider the initial geo-stress,and the reliability is verified by numerical *** calculation of BDZ depth with these formulae allows the corresponding numerical simulation to avoid the time-consuming dynamic calculation process,thus greatly enhancing the calculation *** method was applied to the excavation in Jinping Class II hydropower station to verify its *** results show that the BDZSR method can be applied to blast simulation of underground caverns and provide a new way to study blast-induced damage.

关键词： attenuation of stress wave deep-buried underground building drill and blast in situ stress

Hydrodynamic characteristics and particle tracking of 90° lateral intakes at an inclined river slope

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

water Science and engineering 2024年第2期17卷 197-208页

作者： Wei He Si-yuan Feng Jian Zhang Hong-wu Tang Yang Xiao Sheng Chen Chun-sheng Liu College of water Conservancy and hydropower engineering Hohai UniversityNanjing 210098China State Key Laboratory of Hydrology water resources and Hydraulic engineering Hohai UniversityNanjing 210098China Collaborative Innovation Center on water Safety and water Science Hohai UniversityNanjing 210098China

Lateral intakes are common in *** pump effciency and sediment deposition are determined by the local hydrodynamic characteristics and mainstream division *** hydraulic characteristics of lateral withdrawal from inclined river slopes at different intake elevations should be ***,the division width exhibits significant vertical non-uniformity at an inclined river slope,which should be ***,a three-dimensional(3-D)hydrodynamic and particle-tracking model was developed with the Open Source Field Operation and Manipulation(Open FOAM),and the model was validated with physical model tests for 90°lateral withdrawal from an inclined side *** flow fields,withdrawal sources,and division widths were investigated with different intake bottom elevations,withdrawal discharges,and main channel *** study showed that under inclined side bank conditions,water entered the intake at an oblique angle,causing significant 3-D spiral flows in the intake rather than two-dimensional closed recirculation.A lower withdrawal discharge,a lower bottom elevation of the intake,or a higher main channel velocity could further strengthen this *** average division width and turbulent kinetic energy were smaller under inclined side bank conditions than under vertical bank *** a low intake bottom elevation,a low withdrawal discharge,or a high main channel velocity,the sources of lateral withdrawal were in similar ranges near the local inclined bank in the vertical *** inclined slope conditions,sediment deposition near the intake entrance could be reduced,compared to that under vertical slope *** results provide hydrodynamic and sediment references for engineering designs for natural rivers with inclined terrains.

关键词： Lateral withdrawal Hydrodynamic characteristics Particle tracking Inclined river slope Bottom elevation of intake OpenFOAM

Mechanism of Primary Frequency Regulation for Battery Hybridization in hydropower Plant

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2024年第5期10卷 2127-2137页

作者： Yiwen Liao Weijia Yang Zhecheng Wang Yifan Huang C.Y.Chung State Key Laboratory of water resources and hydropower engineering Science Wuhan UniversityWuhan 430072China Department of Electrical engineering The Hong Kong Polytechnic UniversityHong KongChina

Battery hybridization in hydropower plants is a hydropower flexibility enhancement technology innovation that can potentially expand hydropower’s contributions to the grid,but its fundamental characteristics and influencing mechanisms are still *** this paper,primary frequency regulation(PFR)performance and the mechanism of this new technology are studied.A battery hybridized hydropower plant(BH-HPP)model,based on a field-measured-data-based hydropower plant(HPP)model and a verified battery simplified model,is *** of system stability and dynamics is undertaken for three different battery control strategies by root locus and participation factor *** to conventional HPPs,analysis results theoretically reveal BH-HPP can not only accelerate system regulation rapidity but also effectively enlarge HPP stability region during PFR *** domain simulation verifies the results and further shows synthetic control has better performance among introduced ***,initial design ranges of control parameters considering battery capacity and a renewable energy source scenario case are also *** work could provide theoretical support for flexibility enhancement solutions for hydropower systems.

关键词： Battery hybridization dynamic response hydropower plant primary frequency regulation stability

Evaluation and attribution of trends in compound dry-hot events for major river basins in China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第1期67卷 79-91页

作者： Shaotang XIONG Tongtiegang ZHAO Chengchao GUO Yu TIAN Fang YANG Wenlong CHEN Xiaohong CHEN Key Laboratory of water Security Guarantee in Guangdong-Hong Kong-Marco Greater Bay Area of Ministry of water resources&Sun Yatsen University/Southern Marine Science and engineering Guangdong Laboratory(Zhuhai) Guangzhou 510275China China institute of water Resource and hydropower Research Beijing 100038China Pearl River Hydraulic Research institute Guangzhou 510611China

Concurrent compound dry and hot events(CDHEs)amplified more damange on the ecosystems and human society than individual *** climate change,compound dry and hot events become more frequent on a global *** paper proposes a mathematical method to quantitatively attribute changes of CDHEs to changes of precipitation,change in temperature and change in the dependence between precipitation and *** attribution is achieved by formulating the total differential equation of the return period of CDHEs among Meta-gaussian model.A case study of China is devised based on monthly precipitation and temperature data during the period from 1921 to 2020 for 80 major river *** is found that temperature is the main driving factor of increases in CDHEs for 49 major river basins in China,except for the upper and middle reaches of the Yangtze *** West China,precipitation changes drove the increase in CDHEs in 18 river basins(23%),particularly in parts of North Xinjiang,Qinghai and *** the other hand,dependence between precipitation and temperature dominated changes of CDHEs in 13 river basins(16%)of China with other factors,including parts of South China,East China and Northwestern ***,changes in both the mean and spread of precipitation and temperature can also contribute to changes in CDHEs.

关键词： Climate extreme Compound dry and hot extreme Precipitation Temperature Return period