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Fundamentals and progress of the manifold method based on independent covers

Science China(Technological Sciences) 2024年第4期67卷 966-991页

作者： SU HaiDong LIN ShaoZhong XIE ZhiQiang GONG YaQi QI YongFeng Material and Engineering Structure Department Yangtze River Scientific Research InstituteWuhan 430010China research center of water Engineering Safety and Disaster Prevention of Ministry of water Resources Wuhan 430010China

Aiming to solve mesh generation,computational stability,accuracy control,and other problems encountered with existing numerical methods,such as the finite element method and the finite volume method,a new numerical computational method for continuum mechanics,namely the manifold method based on independent covers(MMIC),is proposed based on the concept of mathematical manifolds,to form partitioned series solutions of partial differential *** partitions,the cover meshes have the characteristics of arbitrary shape,arbitrary connection,and arbitrary *** are expected to fundamentally solve the mesh generation problem and can also simulate the precise geometric boundaries of the CAD model and strictly impose boundary *** the selection of series solutions,local analytical solutions(such as series solutions at crack tips and series solutions in infinite domains)or proper forms of complete series can be used to reflect the local or global characteristics of the physical field to accelerate *** applications are presented.A new method of beam,plate,and shell analysis is *** deformation characteristics of beams,plates,and shells are simulated with polynomial series of suitable forms,and the analysis of curved beams and shells with accurate geometric representation is *** the static elastic analysis of two-dimensional structures,a mesh splitting algorithm is proposed,and h-p version adaptive analysis is carried out with error ***,automatic computation integrated with CAD is *** analysis is also attempted for the solution of differential equations of *** the one-dimensional convection-diffusion equation and Burgers equation,calculation results with high precision are obtained in strong convection and shock wave simulations,avoiding nonphysical *** solving the two-dimensional incompressible Navier-Stokes equation is also *** series solution formula is used to o

关键词： series solutions mesh generation adaptive analysis fixed meshes numerical manifold method

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Synthesis of chitosan-based grafting magnetic flocculants for flocculation of kaolin suspensions

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Journal of Environmental Sciences 2024年第5期139卷 193-205页

作者： Chuang Liu Xiaoyu Wang Sicong Du Wenyan Liang Beijing Key Lab for Source Control Technology of water Pollution/Engineering research center for water Pollution Source Control&Eco-remediation/College of Environmental Science and Engineering Beijing Forestry UniversityBeijing 100083China

A series of novel chitosan-based magnetic flocculants FS@CTS-P(AM-DMC)was prepared by molecular structure *** characterization results showed that FS@CTS-P(AM-DMC)had a uniform size of about 21.46 nm,featuring a typical core-shell structure,and the average coating layer thickness of CTS-P(AM-DMC)was about 5.03 ***@CTS-P(AM-DMC)exhibited excellent flocculation performance for kaolin suspension,achieved 92.54% turbidity removal efficiency under dosage of 150 mg/L,pH 7.0,even at high turbidity(2000 NTU)with a removal efficiency of 96.96%.The flocculation mechanism was revealed to be dominated by charge neutralization under acidic and neutral conditions,while adsorption and bridging effects play an important role in alkaline *** properties of magnetic aggregates during flocculation,breakage,and regeneration were studied at different pH levels and *** the process of magnetophoretic,magnetic particles collide and adsorb with kaolin particles continuously due to magnetic and electrostatic attraction,transform into magnetic chain clusters,and then further form three-dimensional network magnetic aggregates that can capture free kaolin particles and other chain *** image velocimetry confirmed the formation of eddy current of magnetic flocs and experienced three stages:acceleration,stabilization,and deceleration.

关键词： Magnetic flocculation Chitosan Fe_(3)O_(4) Graft copolymerization PIV

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Directional amine-based solvent extraction for simultaneous enhanced water recovery,salt separation and effective descaling from hypersaline brines

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Frontiers of Environmental Science & Engineering 2024年第3期18卷 83-92页

作者： Yuyao Zhang Litao Jia Jin Zhao Xuming Liu Shuyu Dong Chuanyang Liu Yuanyuan Cui Shougang research Institute of Technology Beijing 100043China research center of Environmental Technology in water Pollution Source Identification and Precise Supervision School of EnvironmentTsinghua UniversityBeijing 100084China

The feasibility of simultaneous water recovery,salt separation and effective descaling of hypersaline brine was investigated by diisopropylamine(DIPA)-based directional solvent extraction(DSE),using diluted/concentrated seawater with initial saline concentration range of 12–237 g/L at extraction temperatures of 5 and 15℃,*** water recovery shows an obvious boundary at saline concentration of 115 g/L under dual effect of specific water extraction efficiency and extraction *** Cl^(–) ion concentration in product water is in sharp contrast to the nearly complete removal of SO_(4)^(2–)and hardness ions,indicating that DIPA-based DSE process indeed achieved efficient separation and purification of Cl^(–) ion from hypersaline ***,the radical precipitation of Mg^(2+)and Ca^(2+)ions in form of Mg(OH)_(2)and CaCO_(3)demonstrates effective descaling potential,although it leads to more DIPA residues in dewatered raffinate than product ***,an exponential correlation between the Cl^(–) removal efficiency and specific water extraction efficiency further reveals the intrinsic relationship of water extraction process and transfer of Cl^(–) ion to the product ***,the study provides a novel approach for integrating the water recovery and separation of Cl^(–) ion from ultra-high-salinity brines with radical precipitation of Mg^(2+)and Ca^(2+) ions in one step.

关键词： Hypersaline brines Directional solvent extraction Salt separation Ca^(2+)and Mg^(2+)descaling

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Runoff and Infiltration responses of revegetated slopes to clipping management on the northern Loess Plateau

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International Soil and water Conservation research 2024年第1期12卷 171-183页

作者： Qilin He Binbin Li Fengbao Zhang Nan Shen Mingyi Yang The research center of Soil and water Conservation and Ecological Environment Chinese Academy of Sciences and Ministry of EducationYanglingShaanxi712100China Institute of Soil and water Conservation Chinese Academy of Sciences and Ministry of Water ResourcesYanglingShaanxi712100China Institute of Soil and water Conservation Northwest A&F UniversityYanglingShaanxi712100China water and Soil Conservation Monitoring center of Ministry of water Resources Beijing100053China University of Chinese Academy of Sciences Beijing100049China

Large-scale vegetation restoration can reduce local watershed water yield,limit vegetation establishment and subsequent growth,and influence regional ecosystem *** management by reducing aboveground parts of grassland was gradually recommended and adopted in Grain-for-Green project management to offset these additional ***,scientific evaluation of the effectiveness of clipping management on infiltration and runoff processes is necessary for maintaining the stability of the surface water system and the sustainability of vegetation restoration in semi-arid regions.A field simulated rainfall experiment was conducted with four managed clipping grasslands(mainly bunge needlegrass and Stipa grandis),including no clipping,light clipping,heavy clipping,and complete clipping under three slope gradients(10,20,and 30°)and three rainfall intensities(60,90,and 120 mm/h)to explore the mechanism of runoff and infiltration responses to clipping using structural equation modeling and variation partitioning based on an SCS-CN *** results showed the runoff coefficient of the light clipping,heavy clipping,and complete clipping plots were 1.33,2.22,and 4.22 times that of the no clipping *** light clipping,heavy clipping,and complete clipping plots decreased the infiltration coefficients by 0%,5%,and 26%relative to the no clipping *** intensity dominated runoff and infiltration amounts,and clipping intensity's total effect was stronger than slope *** intensity and slope gradient were more influential on runoff with increasing rainfall *** mutual inhibition effect was between clipping intensity and slope gradient on *** order to maintain the sustainability of restoration,a 25-50%vegetation coverage after clipping maximizes the benefits of increasing runoff and maintaining enough soil water supply that prevents possible soil *** propose that future vegetation restoration policies should evaluate the appropriat

关键词： Runoff Infiltration Grassland clipping management SCS-CN model Structural equation model Variation partitioning

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Mixed D-vine copula-based conditional quantile model for stochastic monthly streamflow simulation

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water Science and Engineering 2024年第1期17卷 13-20页

作者： Wen-zhuo Wang Zeng-chuan Dong Tian-yan Zhang Li Ren Lian-qing Xue Teng Wu College of water Resources and Hydrology Hohai UniversityNanjing 210098China Yellow River research center Hohai UniversityNanjing 210098China

Copula functions have been widely used in stochastic simulation and prediction of ***,existing models are usually limited to single two-dimensional or three-dimensional copulas with the same bivariate block for all *** address this limitation,this study developed a mixed D-vine copula-based conditional quantile model that can capture temporal *** model can generate streamflow by selecting different historical streamflow variables as the conditions for different months and by exploiting the conditional quantile functions of streamflows in different months with mixed D-vine *** up-to-down sequential method,which couples the maximum weight approach with the Akaike information criteria and the maximum likelihood approach,was used to determine the structures of multivariate Dvine *** developed model was used in a case study to synthesize the monthly streamflow at the Tangnaihai hydrological station,the inflow control station of the Longyangxia Reservoir in the Yellow River *** results showed that the developed model outperformed the commonly used bivariate copula model in terms of the performance in simulating the seasonality and interannual variability of *** model provides useful information for water-related natural hazard risk assessment and integrated water resources management and utilization.

关键词： Stochastic monthly streamflow simulation Mixed D-vine copula Conditional quantile model Up-to-down sequential method Tangnaihai hydrological station

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Solute transport and geochemical modeling of the coastal quaternary aquifer, Delta Dahab Basin, South Sinai, Egypt

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Acta Geochimica 2024年第1期43卷 16-39页

作者： Amira Samy Mustafa Eissa Seham Shahen Moustafa M.Said Rabab M.Abou-shahaba Division of water Resources and Arid Land Department of HydrogeochemistryDesert Research CenterCairoEgypt Egypt Desalination research center of Excellence Desert Research CenterCairoEgypt center for water Supply Studies S&E-Physical&Environmental SciencesTexas A&M University Corpus ChristiCorpus ChristiUSA Department of Chemistry Faculty of Science(Girls)Al-Azhar UniversityYousef Abbas StrNasr CityP.O.Box:11754CairoEgypt

The wadi dahab delta is in a dry, arid coastal zone within Egypt’s south Sinai Peninsula’s eastern portion. The primary water source is the Quaternary coastal alluvial aquifer. The groundwater salinity varies from 890to 8213 mg/L, with a mean value of 3417 mg/L. The dissolved major ions have been used to calculate the seawater mixing index(SWMI) using a linear equation that discriminates the groundwater mostly affected by water–rock interaction(SWMI 1>) and other samples mixed with Seawater(SWMI water for specifically chosen groundwater samples ranges from-0.645‰ to +5.212‰ for δ^(18)O and from-9.582‰ to + 22.778‰ for δ^(2)H, where the seawater represented by a Red Sea water sample(δ^(18)O + 1.64‰-δ^(2)H + 9.80‰) and reject brine water are considerably enriched the isotopic groundwater values. The geochemical NETPATH model constrained by the dissolved significant ions, isotopes, and the rock aquifer forming minerals as phases indicate the mixing percent with the seawater ranges from 9% to 97% of seawater from 91% to 3% of original recharge water. According to the SEAWAT 3-D flow models, seawater has penetrated the Northeastern Dahab delta aquifer, with the intrusion zone extending1500 m inland. The salt dissolution, upwelling of saline water, recharge from the upstream mountain block, and seawater encroachment are the primary aspects contributing to the deterioration of groundwater quality. These findings may have significance for effective groundwater withdrawal management in arid locations worldwide with similar hydrogeological systems.

关键词： Groundwater geochemistry Seawater intrusion Solute transport SEAWAT

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Semi-automated detection of rangeland runoff and erosion control berms using high-resolution topography data

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International Soil and water Conservation research 2024年第1期12卷 217-226页

作者： Li Li Changjiang River Scientific research Institute of Changjiang water Resources Commission Wuhan430010China research center on Mountain Torrent&Geologic Disaster Prevention Ministry of Water ResourcesWuhan430010China University of Arizona School of Natural Resources and the EnvironmentTucsonAZ85719USA

An inventory of topographic modifications is essential to addressing their impacts on hydrological and morphological processes in human-altered ***,such inventories are generally *** study presents two workflows for semi-automatic detection of linear earthen runoff and erosion control berms in rangelands using high-resolution topographic *** workflows consist of initial object identification by applying either morphological grayscale reconstruction(MGR)or the Geomorphon(GEO)method,followed by identification refinements through filters based on objects’horizontal and vertical *** sites were selected within the Altar Valley,Arizona,in the southwestern United *** site was used for developing workflows and optimizing filter thresholds,and the other two sites were used to validate *** results showed that:1)The MGR-based workflow methodology could produce final precision and detection rates of up to 92%and 75%,respectively,and take less than 5 s for a 10.1 km^(2) site;2)The workflow based on the MGR method yielded greater identification accuracy than did the GEO workflow;3)Object length,orientation,and eccentricity were important characteristics for identifying earthen berms,and are sensitive to general channel flow direction and berm shape;4)Manual interrogation of topographic data and imagery can significantly improve identification precision *** proposed workflows will be useful for developing inventories of runoff and erosion control structures in support of sustainable rangeland management.

关键词： Earthen berm Rangeland Grayscale morphological reconstruction Geomorphon LiDAR

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Stable hydrogen isoscape in precipitation generated using data fusion for East China

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Science China Earth Sciences 2024年第9期67卷 2972-2988页

作者： Jiacheng CHEN Jie CHEN Xunchang John ZHANG Peiyi PENG State Key Laboratory of water Resources Engineering and Management Wuhan UniversityWuhan 430072China Hubei Key Laboratory of water System Science for Sponge City Construction Wuhan UniversityWuhan 430072China USDA-ARS Oklahoma and Central Plains Agricultural research center El Reno OK 73036USA Southwest research Institute for Hydraulic and water Transport Engineering Chongqing Jiaotong UniversityChongqing 400016China

The stable hydrogen isotope in precipitation is an effective environmental tracer for climatic and hydrologic ***,accurate and high-precision precipitation hydrogen isoscapes are currently unavailable in *** this study,a data fusion method based on Convolutional Neural Networks(CNN)is used to fuse the hydrogen isotopic composition(δ^(2)H_(p))of observations and isotope-equipped general circulation model(iGCM)simulations.A precipitation hydrogen isoscape with a temporal resolution of monthly and a spatial resolution of 50-60 km is established for East China for the 1969-2017 *** to building the isoscape,the performance of three data fusion methods(DFMs)and two bias correction methods(BCMs)is *** results indicate that the CNN fusion method performs the best with a correlation coefficient larger than 0.90 and root mean square error smaller than 10.5‰ when using observation as a *** fusion methods based on back propagation and long short-term memory neural network perform similarly,while slightly outperforming the bias correction ***,the CNN method is used to generate the hydrogen isoscape,and the temporal and spatial distribution characteristics of the hydrogen isotope in precipitation are analyzed based on this *** generated isoscape shows similar spatial and temporal distribution characteristics to *** general,the distribution pattern of δ^(2)H_(p) is consistent with the temperature effect in northern China,and consistent with the precipitation amount effect in southern *** trend of the δ^(2)H_(p) time series is consistent with that of observed precipitation and ***,the generated isoscape effectively reproduces the observations,and has the characteristics of time continuity and relative spatial regularity,which can provide valuable data support for tracking atmospheric and hydrological processes.

关键词： Precipitation Precipitation isotope General circulation model Data fusion Dataset

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Ultra-high specific surface area activated carbon from Taihu cyanobacteria via KOH activation for enhanced methylene blue adsorption

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Chinese Journal of Chemical Engineering 2024年第3期67卷 106-116页

作者： Yifang Mi Wenqiang Wang Sen Zhang Yalong Guo Yufeng Zhao Guojin Sun Zhihai Cao Key Laboratory of Advanced Textile Materials and Manufacturing Technology and Engineering research center for Eco-Dyeing&Finishing of Textiles Ministry of EducationZhejiang Provincial Engineering Research Center for Green and Low-carbon Dyeing&FinishingZhejiang Sci-Tech UniversityHangzhou 310018China Key Laboratory for Technology in Rural water Management of Zhejiang Province Zhejiang University of Water Resources and Electric PowerHangzhou 310018China

Cyanobacteria-based activated carbon(CBAC)was successfully prepared by pyrolysis-activation of Taihu *** the impregnation ratio and activated temperature were 2 and 800-C,respectively,the optimal CBACs possessed an ultra-high specific surface(2178.90 m^(2)·g^(-1))and plenty of micro-and meso-pores,as well as a high pore volume(1.01 cm^(3)·g^(-1)).Ascribed to ultra-high surface area,π-π interaction,electrostatic interaction,as well as hydrogen-bonding interactions,the CBACs displayed huge superiority in efficient dye *** saturated methylene blue adsorption capacity by CBACs could be as high as 1143.4 mg·g^(-1),superior to that of other reported biomass-activated *** adsorption was endothermic and modeled well by the pseudo-second-order kinetic,intra-particle diffusion,and Langmuir *** work presented the effectiveness of Taihu cyanobacteria adsorbent ascribed to its super large specific surface area and high adsorption ability.

关键词： Activated carbon Biomass Dye adsorption Taihu cyanobacteria

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Digitalizing river aquatic ecosystems

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Journal of Environmental Sciences 2024年第3期137卷 677-680页

作者： Yaohui Bai Hui Lin Chenchen Wang Qiaojuan Wang Jiuhui Qu Key Laboratory of Drinking water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China School of Environmental and Municipal Engineering Tianjin Chengjian UniversityTianjin 300384China center for water and Ecology Tsinghua UniversityBeijing 100084China

Traditional river health assessment relies on limited water quality indices and representative organism activity,but does not comprehensively obtain biotic and abiotic information of the ***,we propose a new approach to evaluate the ecological and health risks of river aquatic ***,detailed physicochemical and biological characterization of a river ecosystem can be obtained through pollutant determination(especially emerging pollutants)and DNA/RNA ***,supervised machine learning can be applied to perform classification analysis of characterization data and ascertain river ecosystem ecology and *** proposed methodology transforms river ecosystem health assessment and can be applied in river management.

关键词： Digitalizing River ecosystem health Emerging pollutants High throughput sequencing Machine learning

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