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Features and formulae of sediment incipient motion in vegetated flow environment

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Journal of Hydrodynamics 2024年第2期36卷 331-339页

作者： Yu-xuan Xu Wei-jie Wang Shi-bao Zhang Han-qing Zhao Xue-kai Chen Hai-ping Zhang School of water conservancy North China University of Water Resources and Electric PowerZhengzhou450045China State Key Laboratory of Simulation and Regulation of water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing100038China China Three Gorges Corporation Wuhan430010China

Aquatic vegetation is a vital component of natural river ecosystems,playing a crucial role in maintaining ecological balance,providing habitat and improving water ***,the presence of vegetation results in increased resistance in vegetated channels compared with non-vegetated channels,rendering traditional sediment movement predictions inadequate for the ***,the concept of a vegetation influence factor,denoted by CDah,has been proposed by previous researchers to represent the effect of vegetation on sediment movement in *** this study,we focus on exploring the vegetation resistance coefficient(CD)among the vegetation influence factors,evaluating two different calculation methods for vegetation resistance coefficient,and presenting two expressions through genetic algorithm analysis to predict the incipient flow velocity of sediment in vegetated *** predicted values from the new formulae show excellent agreement with measured data,highlighting the high accuracy of the proposed methods in predicting the incipient flow velocity of *** results provide a solid theoretical basis for understanding the influence of aquatic vegetation on sediment particle movement.

关键词： Vegetation flow vegetation resistance coefficient genetic algorithm sediment initiation

Microstructure evolution and mechanical properties of brazing joint for ultra-thin-walled Inconel 718 considering grain size effect and brazing temperature

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Chinese Journal of Aeronautics 2024年第2期37卷 541-556页

作者： Rui ZHAO Yueshuai SONG Hui KANG Min WAN School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China jiangxi research institute of Beihang University Jiangxi 330000China

The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high demands on its *** achieve this objective,this study investigates the impact of three distinct brazing temperatures and five typical grain sizes on the brazed joints’mechanical properties and microstructure evolution *** evolution analysis was conducted based on Electron Back Scatter Diffraction(EBSD),Scanning Electron Microscopy(SEM),X-Ray Diffraction(XRD),High-Resolution Transmission Electron Microscopy(HRTEM),and Focused Ion Beam(FIB).Besides,the mechanical properties and fracture behavior were studied based on the uniaxial tension tests and in-situ tension *** findings reveal that the brazing joint’s strength is higher for the fine-grain capillary than the coarse-grain one,primarily due to the formation of a dense branch structure composed of G-phase in the brazing *** effects of grain size,such as pinning and splitting,are amplified at higher brazing ***,micro-cracks initiate around brittle intermetallic compounds and propagate through the eutectic zone,leading to a cleavage fracture *** fracture stress of fine-grain specimens is higher than that of coarse-grain due to the complex micro-crack ***,this study contributes significantly to the literature by highlighting the crucial impact of grain size on the brazing properties of ultra-thin-walled Inconel 718 structures.

关键词： EYWORDS Ultra-thin-walled structure Brazing Inconel 718 Grain size effect Brazing temperature

Modified constitutive models for Inconel 718 considering current density and temperature in electrically assisted forming process

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Chinese Journal of Aeronautics 2024年第2期37卷 524-540页

作者： Xuan CUI Rui ZHAO Min WAN School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China jiangxi research institute of Beihang University Jiangxi 330000China

Electrically Assisted Forming(EAF)technology has obvious advantages in material *** develop an effective constitutive model considering electrical effects,room temperature and electrically assisted quasi-static uniaxial tensile tests were conducted using ultrathin nickelbased superalloy plates with a thickness of 0.25 *** research focused on the two most widely recognized effects:the Joule thermal and the electric athermal *** mechanism of current action can be divided into two scenarios:one considering the Joule thermal effect only,and the other considering both effects *** basic constitutive models,namely the Modified-Hollomon model and the Johnson-Cook(J-C)model,were selected to be optimized through the classification of two different situations,and four optimized constitutive models were *** was found that the J-C model with simultaneous consideration of the Joule thermal effect and electric athermal effect had the best prediction effect by comparing the results of these four ***,the accuracy of the optimization model was verified by finite element simulation of the electrically assisted stretching optimization *** results show that the constitutive model can effectively predict the temperature effect caused by the Joule heat effect and the athermal effect of current on the material.

关键词： Joule heating Elastoplasticity Plastic deformation Superalloys Constitutive models

BIM-based framework of automatic tunnel segment assembly and deviation control

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Underground Space 2024年第3期16卷 59-78页

作者： Jian Gong Tengfei Bao Zheng Zhu Hong Yu Yangtao Li The National Key Laboratory of water Disaster Prevention Hohai UniversityNanjing 210098China College of water conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China College of Hydraulic and Environmental Engineering China Three Gorges UniversityYichang 443002China Zhejiang Design institute of water conservancy and Hydro-Electric Power Hangzhou 310002China

The design of universal segments and deviation control of segment assembly are essential for robust and low-risk tunnel construction.A building information modeling(BIM)-based framework was proposed for parametric modeling,automatic assembly,and deviation control of universal ***,segment models of different levels of detail(LoDs)were built based on BIM visual programming language(VPL)for different project life ***,the geometric constraints,requirements,and procedures for parametric segment assembly were distilled to develop a program that combines a novel typesetting algorithm with a 3. path replanning *** is implemented by introducing a point indication matrix,characterizing segments by sides,and manipulating geometries in a ***,3. path replanning,with non-uniform rational B-splines(NURBS)and arcs as basic shapes,was used to resolve unacceptable deviation situations after ***,the proposed framework was validated on a water diversion line and was found to be more effective and accurate than the previous method.

关键词： Parametric generative design BIM Deviation control Typesetting 3. path replanning

Characteristics and influencing factors of greenhouse gas emissions from reservoirs in the Yellow River Basin:A Meta-analysis

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Science China Earth Sciences 2024年第7期67卷 2210-2225页

作者： Shurui HUANG Peijia ZHANG Wenxiu ZHENG Jiajia ZHANG Yang LI Yuanjian WANG Enhui JIANG Shaoda LIU Xinghui XIA State Key Laboratory of water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 00875China Yellow River institute of Hydraulic research Yellow River Conservancy CommissionZhengzhou 450003China

Reservoir construction and operation profoundly alter the hydrological,hydrodynamic,and carbon and nitrogen cycling processes of ***,current research still lacks a systematic understanding of the characteristics of greenhouse gas(GHG)emissions from reservoirs in arid/semi-arid *** study integrates existing monitoring data to discuss the characteristics of GHG emissions from reservoirs in the Yellow River Basin and illustrate the controlling factors and underlying mechanism of these *** results indicate that while CO_(2) emission flux from reservoirs is lower than that from river channels,the emission fluxes of CH_(4) and N_(2)O are 1.9 times and 10 times those from rivers,respectively,indicating that the emission of GHG with stronger radiative effect is significantly enhanced in *** to the reservoirs in humid climates(e.g.,the Three Gorges Reservoir),reservoirs in the Yellow River Basin exhibit relatively lower emissions of CO_(2) and CH_4 due to lower organic matter concentrations,but significantly higher N_(2)O emissions due to higher nitrogen *** Carlo simulations for 23. reservoirs in the Yellow River Basin showed that total emission of the three GHGs is 3.05 Tg CO_(2)-eq yr^(-1),accounting for 0.3.% of the total emission from global reservoirs and lower than the area percentage of the basin(0.53.).This study has important implications on revealing the GHG emission characteristics and control mechanisms of reservoirs in arid/semi-arid regions.

关键词： Yellow River Basin Reservoir Greenhouse gas Emission flux water quality

Spatio-temporal Variation Characteristics of Extreme Climate Events and Their Teleconnections to Large-scale Ocean-atmospheric Circulation Patterns in Huaihe River Basin,China During 1959–2019

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Chinese Geographical Science 2024年第1期34卷 118-134页

作者： YAO Tian ZHAO Qiang WU Chuanhao HU Xiaonong XIA Chuan'an WANG Xuan SANG Guoqiang LIU Jian WANG Haijun School of water conservancy and Environment University of JinanJinan250022China Yangtze institute for Conservation and Development Hohai UniversityNanjing210098China Zijin School of Geology and Mining Fuzhou UniversityFuzhou350108China water research institute of Shandong Province Jinan250014China Shandong Provincial Bureau of Hydrology and water Resources Jinan250100China

Huaihe River Basin(HRB) is located in China’s north-south climatic transition zone,which is very sensitive to global climate *** on the daily maximum temperature,minimum temperature,and precipitation data of 40 meteorological stations and nine monthly large-scale ocean-atmospheric circulation indices data during 1959–2019,we present an assessment of the spatial and temporal variations of extreme temperature and precipitation events in the HRB using nine extreme climate indices,and analyze the teleconnection relationship between extreme climate indices and large-scale ocean-atmospheric circulation *** results show that warm extreme indices show a significant(P < 0.05) increasing trend,while cold extreme indices(except for cold spell duration) and diurnal temperature range(DTR) show a significant decreasing ***,all extreme temperature indices show significant mutations during ***,a stronger warming trend occurs in eastern HRB than western HRB,while maximum 5-d precipitation(Rx5day) and rainstorm days(R25) show an increasing trend in the southern,central,and northwestern regions of *** oscillation(AO),Atlantic multidecadal oscillation(AMO),and East Atlantic/Western Russia(EA/WR) have a stronger correlation with extreme climate indices compared to other circulation *** and AMO(EA/WR) exhibit a significant(P < 0.05) negative(positive)correlation with frost days and diurnal temperature *** warm events are strongly correlated with the variability of AMO and EA/WR in most parts of HRB,while extreme cold events are closely related to the variability of AO and AMO in eastern *** contrast,AMO,AO,and EA/WR show limited impacts on extreme precipitation events in most parts of HRB.

关键词： extreme climate indices Sen’s slope variation mutation test atmospheric circulation indices Pearson’s correlation analysis Huaihe River Basin(HRB),China

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

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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

An efficient approach for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic excitations

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 677-690页

作者： Huang Huan Li Yingxiong Li Yuyu College of water conservancy and Civil Engineering South China Agricultural UniversityGuangzhou 510642China institute of Smart City and Intelligent Transportation Southwest Jiaotong UniversityChengdu 611756China

An efficient approach is proposed for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic *** concentrated plastic hinges,described by the Bouc-Wen model,are assumed to occur at the two ends of a linear-elastic beam *** auxiliary differential equations governing the plastic rotational displacements and their corresponding hysteretic displacements are replaced with linearized differential ***,the two sets of equations of motion for the original nonlinear system can be reduced to an expanded-order equivalent linearized equation of motion for equivalent linear *** solve the equation of motion for equivalent linear systems,the nonstationary random vibration analysis is carried out based on the explicit time-domain method with high ***,the proposed treatment method for initial values of equivalent parameters is investigated in conjunction with parallel computing technology,which provides a new way of obtaining the equivalent linear systems at different time *** on the explicit time-domain method,the key responses of interest of the converged equivalent linear system can be calculated through dimension reduction analysis with high *** examples indicate that the proposed approach has high computational efficiency,and shows good applicability to weak nonlinear and medium-intensity nonlinear systems.

关键词： nonstationary random vibration plastic hinge equivalent linearization method explicit time-domain method parallel computation

Advancement of metal(loid)research on farmland

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Frontiers of Agricultural Science and Engineering 2024年第3期11卷 442-467页

作者： Qiang ZHENG Chenchen WEI Yanbing CHI Peiling YANG College of water Resources and Civil Engineering China Agricultural UniversityBeijing 100083China Agricultural water conservancy Department Changjiang River Scientific Research InstituteWuhan 430019China Zhejiang University of water Resources and Electric Power Hangzhou 310018China

Metal(loid)pollution has emerged as a pressing environmental issue in agriculture,garnering extensive public ***(loid)s are potentially toxic substances that infiltrate the soil through diverse pathways,leading to food chain contamination via plant uptake and subsequent animal *** poses a serious threat to environmental quality,food security,and human ***,the remediation of metal(loid)-contaminated agricultural soil is an urgent concern demanding immediate ***,the majority of research papers concentrate on established,isolated remediation technologies,often overlooking comprehensive field management *** is imperative to provide a comprehensive summary of remediation technologies and identify future development *** review aims to comprehensively summarize a range of soil remediation and enhancement technologies,incorporating insights from multiple disciplines including physics,chemistry,biology,and their interdisciplinary *** review examines the mechanisms of action,suitable scenarios,advantages,disadvantages,and benefits associated with each remediation *** relevant is the examination of metal(loid)sources,as well as the mechanisms behind both established and innovative,efficient remediation and enhancement ***,the future evolution of remediation technologies are considered with the aim of offering a scientific research foundation and inspiration to fellow *** is intended to facilitate the advancement of remediation technologies and establish a robust foundation for sustainable development of soil.

关键词： Metal(loid)pollution metal(loid)remediation metal(loid)sources soil