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Parameterized expressions for an improved Rouse equation

International Journal of Sediment Research 2013年第4期28卷 523-534页

作者： Chen CHENG Zhi-yao SONG Yi-gang WANG Jin-shan ZHANG School of Marine Sciences Nanjing University of Information Science&Technology Key Laboratory of Virtual Geographic Environment under Ministry of Education and Jiangsu Key Laboratory for Numerical Simulation of Large-Scale Complex SystemNanjing Normal University College of harbor Coastal and Offshore EngineeringHohai University river harbor engineering department Nanjing Hydraulic Research Institute

The equilibrium profile of suspended sediment concentration（SSC） in steady,uniform turbulent flow has been extensively studied since the proposition of Rouse equation（Rouse,1937）.Many researchers keep studying and attempting to improve the Rouse equation by modifying the mixing length *** and dey（2009） improved Rouse equation based on the modified sediment diffusivity,however,their proposed sediment diffusivity has two parameters,the depth modification factor α and the reciprocal of the sediment Schmidt number β=1/S;,and the corresponding expressions were not given properly in their *** paper aims to parameterize the relevant coefficients,the results shows:（1）α is parameterized from a reasonable approximation by the analysis of surface boundary condition of SSC;（2） considering some effect factors on the settling velocity,β can be expressed by an extended and modified Montcs-Ippen formula,and its related parameters are calibrated by substantial data about the relationship between the primary Rouse parameter Z.= ω;/*** its counterpart Z.’=ω;/β*** verification with some experimental and field datasets,and comparison with related formula,the results show that the sediment diffusivity and SSC profiles have a good agreement with measured data used the present parameterized expressions of a and β,so the present improved Rouse equation is reasonable,and can be applied in practical ***,an approximation and simplified expression of the improved Rouse equation is deduced by using the approach of perturbation,which can be applied easily for the estimation of suspended sediment transport rate.

关键词： Improved Rouse equation Parameterization Sediment transport

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Prediction of Salinity Variations in a Tidal Estuary Using Artificial Neural Network and Three-dimensional Hydrodynamic Models

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Computational Water, Energy, and Environmental engineering 2017年第1期6卷 107-128页

作者： Weibo Chen Wencheng Liu Weiche Huang Hongming Liu National Science and Technology Center for disaster Reduction Taiwan department of Civil and disaster Prevention engineering National United University Taiwan ph.d. program in Materials and Chemical engineering National United University Taiwan

The simulation of salinity at different locations of a tidal river using physically-based hydrodynamic models is quite cumbersome because it requires many types of data, such as hydrological and hydraulic time series at boundaries, river geometry, and adjusted coefficients. Therefore, an artificial neural network (ANN) technique using a back-propagation neural network (BPNN) and a radial basis function neural network (RBFNN) is adopted as an effective alternative in salinity simulation studies. The present study focuses on comparing the performance of BPNN, RBFNN, and three-dimensional hydrodynamic models as applied to a tidal estuarine system. The observed salinity data sets collected from 18 to 22 May, 16 to 22 October, and 26 to 30 October 2002 (totaling 4320 data points) were used for BPNN and RBFNN model training and for hydrodynamic model calibration. The data sets collected from 30 May to 2 June and 11 to 15 November 2002 (totaling 2592 data points) were adopted for BPNN and RBFNN model verification and for hydrodynamic model verification. The results revealed that the ANN (BPNN and RBFNN) models were capable of predicting the nonlinear time series behavior of salinity to the multiple forcing signals of water stages at different stations and freshwater input at upstream boundaries. The salinity predicted by the ANN models was better than that predicted by the physically based hydrodynamic model. This study suggests that BPNN and RBFNN models are easy-to-use modeling tools for simulating the salinity variation in a tidal estuarine system.

关键词： Salinity Variation Artificial Neural Network Backpropagation Algorithm Radial Basis Function Neural Network Three-dimensional Hydrodynamic Model Tidal Estuary

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dynamic Behaviors of a Moored Floating Structure with Flexible Skirts

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Journal of Energy and Power engineering 2016年第1期10卷 13-22页

作者： Wen-Kai Weng duc-Tru Tran Ruey-Syan Shih Research Center for Ocean Energy and Strategies National Taiwan Ocean University Keelung 202 Taiwan R.O.C. ph.d. program in department of harbor and river engineering National Taiwan Ocean University Keelung 202 Taiwan R.O.C. department of Construction and Spatial design. Tungnan University New Taipei City 222 Taiwan R.O.C

A numerical model was developed by using the dual boundary element method to investigate the dynamic behavior of a moored floating structure with a pair of vertical and flexible skirts attached at its bottom in the linear wave field. Theoretical conception is based on potential theory with linear external forces. The motions of the structure were assumed to be small and linear. The flexible skirts mounted beneath the structure were assumed uniform flexural rigidity and the thickness of the skirts was negligible. Comparison between the present model and Gesraha＇s solution was made to verify the results for a moored floating structure with or without rigid skirts. The influence of the skirt rigidity on the moored floating structure, moored lines and waves is investigated in this study. The results show that, the natural frequencies of structure＇s oscillation, moored force, wave reflection and transmission tend to the region of short-period waves when the flexible rigidity gradually decreases. Positive correlation exists between the aft mooring force and the pitch motion of the floating structure.

关键词： Floating structure dual boundary element method response amplitude operators flexible skirts.

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Wave Attenuation Properties of double Trapezoidal Submerged Breakwaters on Flat-Bed

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Transactions of Tianjin University 2012年第6期18卷 401-410页

作者：曹永港蒋昌波白玉川 State Key Laboratory of Hydraulic engineering Simulation and Safety Tianjin University School of Hydraulic engineering Changsha University of Science&Technology Institute of Sediment on river and Coast engineering Tianjin University

This paper investigates the wave attenuation properties of the double trapezoidal submerged breakwaters on the flat-bed by conducting physical experiments subjected to linear and cnoidal incident *** method of Goda's two points is used to separate the heights of incident,reflected and transmitted waves based on the experimental *** possible factors affecting the wave attenuation properties of the double trapezoidal submerged breakwaters(i.e.,the relative submerged water depth,relative breakwater spacing,wave steepness and relative wave height) are investigated with respect to the reflection and transmission *** results show that there is a range,within which the breakwater spacing has little impact on the reflection coefficient,and the transmission coefficient tends to be a *** influence of the wave steepness is reduced while the breakwater spacing is too large or too *** the range of the relative wave height tested in this study,the reflection and transmission coefficients increase and decrease with the relative wave height,*** double trapezoidal submerged breakwaters model indicates a good attenuation effect for larger wave steepness,big relative wave height and within the range of the relative breakwater spacing between 12.5 and 14 according to linear and cnoidal *** changes of wave energy spectra between the double submerged breakwaters on the flat-bed are investigated by the fast Fourier transform(FFT) method,showing that wave energy dissipation can be reached more effectively when the relative breakwater spacing is 12.5.

关键词： linear wave cnoidal wave double trapezoidal submerged breakwaters reflection coefficient transmis- sion coefficient attenuation coefficient

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Filler effect of fine particle sand on the compressive strength of mortar

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International Journal of Minerals,Metallurgy and Materials 2011年第2期18卷 240-246页

作者： Chai Jaturapitakkul Jatuphon Tangpagasit Sawang Songmue Kraiwood Kiattikomol department of Civil engineering Faculty of Engineering King Mongkut's University of Technology Thonburi department of Civil engineering Faculty of Engineering Rajamangala University of Technology Thanyaburi

The river sand, which is a non-pozzolanic material, was ground into 3 different particle sizes. Portland cement type I was replaced by the ground river sands at 10wt%？40wt% of binder to cast mortar. Compressive strengths of mortar were investigated and the filler effect of different fine particles of sand on the compressive strength of mortar was evaluated. The results show that the compressive strength of mortar contributed from the filler effect of smaller particles is higher than that of the coarser ones. The difference in compressive strength of mortar tends to be greater as the difference in ground river sand fineness increases. The results also suggest that ASTM C618 specification is not practically suitable for specifying pozzolan in concrete since the strength activity index of mortar containing ground river sand （high crystalline phase） with 33.8wt% of particles retained on a 45-μm sieve can pass the strength requirement.

关键词： mortar sand particle size compressive strength hydration

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Simultaneous removal of Pb and MTBE by mixed zeolites in fixed-bed column tests

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Journal of Environmental Sciences 2022年第12期34卷 41-49页

作者： Yunhui Zhang FeiWang Benyi Cao Hailong Yin Abir Al-Tabbaa College of Environmental Science and engineering Tongji UniversityShanghai 200092China Key Laboratory of Yangtze river Water Environment Ministry of EducationTongji UniversityShanghai 200092China department of engineering University of CambridgeCambridgeCB21PZUK Institute of Geotechnical engineering School of TransportationSoutheast UniversityNanjing 210096China State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control Nanjing Institute of Environmental SciencesMinistry of Ecology and Environment of ChinaNanjing 210042China

The co-contamination of metals and organic pollutants,such as Pb and methyl tert-butyl ether(MTBE),in groundwater,has become a common and major phenomenon in many contaminated *** study evaluated the feasibility of their simultaneous removal with permeable reactive barrier(PRB)packed with mixed zeolites(clinoptilolite and ZSM-5)using fixed-bed column tests and breakthrough curve *** effect of grain size on the permeability of PRB and removal efficacy was also assessed by granular and power *** replacement of granular clinoptilolite by powder clinoptilolite largely reduced the breakthrough time but increased the saturation time nearly *** column adsorption capacity of clinoptilolite powders almost tripled that of clinoptilolite granules(130.6mg/g versus 45.3 mg/g)due to higher specific surface *** minimum thickness and corresponding longevity of PRB were calculated as 7.12 cm and 321.5 min when 5%of granular clinoptilolite was mixed with 5%ZSM-5 and 90%sand as mixed PRB reactive media compared with 10.86 cm and 1230.2 min for the application of powder *** study is expected to provide theoretical support and guidance for the practical application of mixed adsorbents in PRBs.

关键词： MTBE Zeolite Heavy metal Permeable reactive barrier Groundwater remediation

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Human impacts on runoff regime of middle and lower Yellow river

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Water Science and engineering 2011年第1期4卷 36-45页

作者： Yan-fang SANG dong WANG Ji-chun WU Qing-ping ZHU Ling WANG department of Hydrosciences School of Earth Sciences and Engineering Nanjing University Nanjing 210093 P. R. China China Water International engineering Consulting Co. Ltd. Beijing 100053 P.. R. China Hydrology Bureau of Yellow river Conservancy Committee of Ministry of Water Resources Zhengzhou 450001 P. R. China

In this study, the 54-year （1950 to 2003） monthly runoff series from February, April, August, and November, as well as the annual runoff series, measured at both Huayuankou and Lijin hydrological stations were chosen as representative data, and the continuous wavelet transform （CWT） was applied to analyze the impacts of human activities on the runoff regime of the middle and lower Yellow river. A point of change in 1970 was first determined, and the observed series before 1970 were considered natural runoff while those after 1970 were restored according to linear trends. Then, the CWT was applied to both the observed and restored runoff series to reveal their variations at multi-temporal scales, including the five temporal ranges of 1-4, 6-8, 9-12, 16-22, and 22-30 years, and the trend at the temporal scale of 54 years. These analysis results are compared and discussed in detail. In conclusion, because of the impacts of human activities, there have been significant changes in the runoff regime in the middle and lower Yellow river since 1970. The decaying tendency of annual runoff has become more pronounced, and the inner-annual distribution of runoff has changed, but human activities have had little impact on the periodic characteristics of runoff.

关键词： time series analysis wavelet analysis runoff human activity Yellow river

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Road effects on vegetation composition in a saline environment

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Journal of Plant Ecology 2012年第2期5卷 206-218页

作者： Sheng-Lan Zeng Ting-Ting Zhang Yu Gao Bo Li Chang-Ming Fang S.Luke Flory Bin Zhao Coastal Ecosystems Research Station of the Yangtze river Estuary Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringInstitute of Biodiversity ScienceFudan University220 Han Dan RoadShanghai 200433P.R.China department of Biology Indiana University1001 East 3rd StreetBloomingtonIN 47405USA

Aims Road effects from maintenance and traffic have the potential to alter plant communities,but the exact relationships between these effects and changes in plant community composition have not often been studied in diverse *** determine the direction and level of community composition changes in saline environment due to road effects,we conducted a study along roads of different ages and in nearby non-road(***)areas in the Yellow river delta,***,to potentially elucidate the mechanisms underlying the changes in the richness and composition of plant communities along roads,we evaluated physiochemical changes in soil of roadside and non-road *** Floristic and environmental data were collected along roadside of different ages and nearby non-road *** evaluate plant communities at each site,six 2 m 32 m quadrats were placed at 3-m intervals along roads and six quadrats were arranged randomly in non-road *** determine the difference in plant community composition betweenroadside andnon-road areas,wemeasuredspecies richness and the abundance of each species,examined species turnover and floristic dissimilarity between the two areas and positioned plant species and sites in an abstract multivariate *** community(species richness,percentage of halophytes)and soil physicochemical properties(ph,salinity,moisture content,bulk density,nitrate and ammonium nitrogen concentration)were compared between roadside and non-road areas(young roadside *** non-road areas,old roadside *** non-road areas)by using *** and ordination techniques were used to examine the relationship between vegetation and related environmental variables in both roadside and non-road *** Findings For both the young and old roadside areas,species richness in roadside areas was significantly higher than in non-road areas and high floristic dissimilarity values indicated that roadside and non-roa

关键词： road effect salinization species composition vegetation–environment relationships

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Experiments and modelling of phenanthrene biodegradation in the aqueous phase by a mixed culture

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Journal of Environmental Sciences 2006年第1期18卷 147-153页

作者： LIU Xiang MAO Xiao-min YANG Jian-gang d.A. Barry LI Ling department of Environmental Science and engineering Tsinghua University Beijing 100084 China Contaminated Land Assessment and Remediation Research Centre Institute for Infrastructure and Environment School of Engineering and Electronics The University of Edinburgh Edinburgh EH9 3JL United Kingdom Chinese Academy of Transportation Sciences Ministry of Communications Beijing 100029 China Environmental engineering division School of Engineering the University of Queensland St. Lucia QLD 4072 Australia Centre for Eco-Environmental Modelling Hohai University Nanjing 210098. China

Pollution by polycyclic aromatic hydrocarbons（PAHs） is widespread due to tmsuitable disposal of industrial waste. They are mostly defined as priority pollutants by environmental protection authorities worldwide. phenanthrene, a typical PAH, was selected as the target in this paper. The PAH-degrading mixed culture, named ZM, was collected from a petroleum contaminated river bed. This culture was injected into phenanthrene solutions at different concentrations to quantify the biodegradation process. Results show near-complete removal of phenanthrene in three days of biodegradation if the initial phenanthrene concentration is low. When the initial concentration is high, the removal rate is increased but 20%-40% of the phenanthrene remains at the end of the experiment. The biomass shows a peak on the third day due to the combined effects of microbial growth and decay. Another peak is evident for cases with a high initial concentration, possibly due to production of an intermediate metabolite. The ph generally decreased during biodegradation because of the production of organic acid. Two phenomenological models were designed to simulate the phenanthrene biodegradation and biomass growth. A relatively simple model that does not consider the intermediate metabolite and its inhibition of phenanthrene biodegradation cannot fit the observed data. A modified Monod model that considered an intermediate metabolite （organic acid） and its inhibiting reversal effect reasonably depicts the experimental results.

关键词： biodegradation model phenanthrene microbial growth and decay Monod growth model

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Nitrogen addition mediates the response of foliar stoichiometry to phosphorus addition: a meta-analysis

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Ecological Processes 2021年第1期10卷 804-816页

作者： Chengming You Changhui Peng Zhenfeng Xu Yang Liu Li Zhang Rui Yin Lin Liu Han Li Lixia Wang Sining Liu Bo Tan Paul Kardol Forestry Ecological engineering in the Upper Reaches of the Yangtze river Key Laboratory of Sichuan Province and National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze river and Rainy Area of West China Plantation Ecosystem Permanent Scientifc Research Base Institute of Ecology and ForestrySichuan Agricultural University211 Huimin RoadWenjiang DistrictChengdu 611130SichuanPeople’s Republic of China. department of Biological Science Institute of Environment SciencesUniversity of Quebec at MontrealCase Postale 8888Succursale Centre-VilleMontrealQC H3C 3P8Canada. Laboratory for Ecological Forecasting and Global Change College of ForestryNorthwest A&F UniversityNo.3 Taicheng RoadYangling 712100People’s Republic of China. department of Community Ecology Helmholtz-Centre for Environmental Research-UFZTheodor-Lieser-Strasse 406110 HalleSaaleGermany. College of Animal Science and Technology Sichuan Agricultural UniversityChengdu 611130People’s Republic of China. department of Forest Ecology and Management Swedish University of Agricultural Science90183 UmeåSweden.

Background:Changes in foliar nitrogen(N)and phosphorus(P)stoichiometry play important roles in predicting the efects of global change on ecosystem structure and ***,there is substantial debate on the efects of P addition on foliar N and P stoichiometry,particularly under diferent levels of N ***,we conducted a global meta-analysis to investigate how N addition alters the efects of P addition on foliar N and P stoichiometry across different rates and durations of P addition and plant growth types based on more than 1150 ***:We found that P addition without N addition increased foliar N concentrations,whereas P addition with N addition had no *** positive efects of P addition on foliar P concentrations were greater without N addition than with N ***,the efects of P addition on foliar N,P and N:P ratios varied with the rate and duration of P *** particular,short-term or low-dose P addition with and without N addition increased foliar N concentration,and the positive efects of short-term or low-dose P addition on foliar P concentrations were greater without N addition than with N *** responses of foliar N and P stoichiometry of evergreen plants to P addition were greater without N addition than with N ***,regardless of N addition,soil P availability was more efective than P resorption efciency in predicting the changes in foliar N and P stoichiometry in response to P ***:Our results highlight that increasing N deposition might alter the response of foliar N and P stoichiometry to P addition and demonstrate the important efect of the experimental environment on the *** results advance our understanding of the response of plant nutrient use efciency to P addition with increasing N deposition.

关键词： Ecological stoichiometry Plant nutrient regime Nutrient resorption efciency Soil N and P availability Global change Global synthesis

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