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3D mathematical model for suspended load transport by turbulent flows and its applications

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science china(Technological sciences) 2004年第2期47卷 237-256页

作者： LU Yongjun1,DOU Guoren1,HAN Longxi2,SHAO Xuejun3 & YANG Xianghua1,3 1.nanjing Hydraulic Research Institute,nanjing 210029,china 2.college of environmental Engineering of Hohai university,nanjing 210098,china 3.Department of Hydraulic Engineering,Tsinghua university,Beijing 100084,china nanjing Hydraulic Research Institute Nanjing China college of environmental Engineering of Hohai university Nanjing China Department of Hydraulic Engineering Tsinghua University Beijing China

This paper presents a 3D mathematical model for suspended load transport in turbulent flows. Based on Dous stochastic theory of turbulent flow, numerical schemes of Reynolds stresses for anisotropic turbulent flows were obtained. A refined wall function was employed to treat solid wall boundaries. The equations for 2D suspended load motion and sorting of bed material have been expanded into 3D cases. Numerical results are validated by the measured data of the Gezhouba Project, and proved to be in good agreement with the experimental. The present method has been employed to simulate sediment erosion and deposition in the dam area of Three Gorges Project, and for the operation of the project, siltation process and deposition pattern in the near-dam area of the reservoir, size distribution of the deposits and bed material, and flow fields and sediment concentration fields at different time and elevations are predicted. The predicted results are close to the experimental observations in physical model studies. Thus, a new method is established for 3D simulation of sediment motion in dam areas of multi-purpose water projects.

关键词： turbulent flows, Dou's stochastic theory, nonuniform suspended load, riverbed erosion and deposition, 3D mathematical model, Three Gorges Project.

Effect of Long-Term Fertilization on Organic Carbon and Nitrogen in a Subtropical Paddy Soil

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Pedosphere 2009年第6期19卷 727-734页

作者： HUANG Qian-Ru HU Feng HUANG Shan LI Hui-Xin YUAN Ying-Hong PAN Gen-Xing ZHANG Wei-Jian college of resources and environmental sciences Nanjing Agricultural University Nanjing 210095 (China) Jiangxi Institute of Red Soils Jinxian 331717 (China) Institute of Applied Ecology Nanjing Agricultural University Nanjing 210095 (China)

A long-term experiment beginning in 1981 in Jinxian County of Jiangxi Province, subtropical china, was conducted in a paddy field under a double rice cropping system with four different fertilization regimes, including 1) no fertilizer as control (CK), 2) balanced chemical N, P, and K fertilizers (NPK), 3) organic manure using milk vetch and pig manure in the early and late rice growing season, respectively (OM), and 4) balanced chemical fertilizers combined with organic manure (NPKM). Samples (0-17 cm) of the paddy field soil, which was derived from Quaternary red clay, were collected after the late rice harvest in November 2003 for determination of total organic carbon (TOC) and total nitrogen (TN) and fractions of organic C and N. Results showed that TOC and TN in the NPKM and OM treatments were significantly higher than those in other two treatments (CK and NPK). Application of organic manure with or without chemical fertilizers significantly increased the contents of all fractions of organic C and N, whereas chemical fertilizer application only increased the contents of occluded particulate organic C (oPOC) and amino acid N. In addition, application of organic manure significantly enhanced the proportions of free particulate organic carbon (fPOC) and oPOC in total C, and those of amino sugar N and amino acid N (P < 0.01) in total N. In contrast, chemical fertilizer application only increased the proportions of oPOC and amino acid N (P < 0.05). There were no significant differences in either contents or proportions of soil organic C and organic N fractions between the NPKM and OM treatments. These indicated that organic manure application with or without chemical fertilizers played the most significant role in enhancing soil organic C and N quantity and quality in the paddy field studied.

关键词： chemical fertilizers double rice cropping system organic manure

Effect of Saline Aquaculture Effluent on Salt-Tolerant Jerusalem Artichoke (Helianthus tuberosus L.) in a Semi-Arid Coastal Area of china

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Pedosphere 2006年第6期16卷 762-769页

作者： ZHAO Geng-Mao LIU Zhao-Pu CHEN Ming-Da KOU Wei-Feng college of resources and environmental Scivnces Nanjing Agricultural University Nanjing 210095 China

An experiment with six treatments: CK1 (rainfed), CK2 (irrigated with freshwater), and 4 treatments of saline aquaculture effluent blended with brackish groundwater at different ratios of 1:1, 1:2, 1:3, and 1:4 (v/v) was carried out during 2004 to assess the effect of saline aquaculture effluent on plant growth and soil properties in the Laizhou region, Shandong Province, china and to determine an optimal salinity threshold for aquaculture effluent. Cumulative evapotranspiration for the saline aquaculture effluent irrigation and non-irrigation treatments was lower than that for the freshwater irrigation treatment. Soil electrical conductivity was higher with respect to saline aquaculture effluent irrigation treatment compared to that with respect to non-irrigation or freshwater irrigation treatment. For Jerusalem artichoke (Helianthus tuberosus L.), in comparison to the freshwater treatment, plant height and aboveground biomass for the 1:3 and 1:4 treatments were constrained, whereas stem width and root biomass were enhanced. Concomitantly, higher tuber yield was obtained for the 1:3 and 1:4 treatments compared to that for CK1 and 1:1 treatments. Nitrogen and phosphorus were higher in tubers of the 1:4 treatment. This study demonstrated that saline aquaculture effluent could be used successfully to irrigate Jerusalem artichoke with higher tuber yield and nutrient removal.

关键词： Jerusalem artichoke (Helianthus tuberosus L.) nutrient uptake saline aquaculture effluent irrigation soil properties tuber yield

Thermal Conductivity and Heat Transfer Coefficient of Concrete

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Journal of Wuhan university of Technology(Materials science) 2011年第4期26卷 791-796页

作者：郭利霞 North china university of Water resources and Electric Power

A very simple model for predicting thermal conductivity based on its definiensis was presented. The thermal conductivity obtained using the model provided a good coincidence to the investigations performed by other authors. The heat transfer coefficient was determined by inverse analysis using the temperature measurements. From experimental results, it is noted that heat transfer coefficient increases with the increase of wind velocity and relative humidity, a prediction equation on heat transfer coefficient about wind velocity and relative humidity is given.

关键词： thermal conductivity heat transfer coefficient relative humidity wind velocity

Occurrence of nitrification-denitrification and gaseous nitrogen loss process in flooded rice soil

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Progress in Natural science:Materials International 2007年第1期17卷 6-10页

作者： NI Wuzhong, LI Jianping and ZHU Zhaoliang (college of environmental and Resource sciences, Zhejiang university, Hangzhou 310029, china college of Biosystems Engineering and Food science, Zhejiang university, Hangzhou 310029, china Institute of Soil science, Chinese Academy of sciences, nanjing 210008, china) college of environmental and Resource sciences Zhejiang University Hangzhou 310029 China college of Biosystems Engineering and Food science Zhejiang University Hangzhou 310029 China Institute of Soil science Chinese Academy of Sciences Nanjing 210008 China

Flooding in wetland rice fields soon after transplanting results in displacement of soil air (including O2). Thus any dissolved O2 in the pore water is consumed out by microbial respiration in a short period. Supply of O2 to the flooded rice soil is by diffusion of O2 through the standing floodwater and consumption at the soil-water interface, and by exudation of O2 by rice roots and subsequent diffusion of O2 into the rhizosphere. The greater potential consumption of O2 compared to the renewal rate results in the development of distinct soil layers: oxidized soil layers under soil-water interface and in the rhizosphere, and reduced soil layers or reduced bulk soil. Nitrification in oxidized soils and denitrification in reduced soils have been known. Currently, denitrification in oxidized soils, even in standing floodwater, has also been identified. In this article, we present a modified nitrification and denitrification occurring mechanism in flooded rice soil.

关键词： denitrification flooded rice soil gaseous nitrogen loss nitrification.

NUMERICAL STUDY ON THE PURIFICATION PERFORMANCE OF RIVERBANK

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Journal of Hydrodynamics 2007年第5期19卷 643-652页

作者： DAI Yu WANG De-guan college of environmental science and Engineering Hohai University Nanjing 210098 China

During the rain time, the runoff infiltrates into the riverbank through the collecting gutter and slope surface. The city runoff is generally polluted by organic, oil, heavy metal particulates, etc. The pollutants moving with the water through the riverbank experience advection, dispersion, diffusion, adsorption, biochemical reaction and plant uptaking processes. In this article, a mathematical model was developed to simulate the performance of pollutant removal of the riverbank. The model took those main mechanisms into account. The modified Richards equation was used in simulating flow field. The mass balance law was employed in deriving the equation for pollutant transport, where the diffusion and dispersion were described with the Fick-type law, the adsorption was macroscopically expressed as form isotherm, and the bio-chemical degradation process was assumed to follow the Monod kinetics. The NH3-N and TP were considered in the present model. The mathematical model was descritized with a finite element numerical model, which was applied to two types of model riverbanks. In the model test, the hydraulic loading was assumed to have the intermittent pattern simulating the storm runoff of certain return period, and the values of the rainfall runoff and concentrations of the NH3-N and TP were taken from the model test. The computed overall removal rates for the NH3-N and TP in 6 cases are in the range of 88%-98%, 87%-97%, respectively. The differences between the computed and tested overall removal rates for the NH3-N and TP are less than 5%. The time-varying oscillation pattern of the concentrations of the NH3-N and TP were rationally simulated, which shows that the model presented in this article can be used to assess the purification performance of the riverbank constructed with sand or soil.

关键词： riverbank numerical modelling purification,pollutant experiments

MODEL OF CALCULATING WATER QUANTITY NEEDED TO DILUTE AND PURIFY POLLUTANTS IN RIVER NETWORK ANDITS APPLICATIONS

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Journal of Hydrodynamics 2005年第4期17卷 418-428页

作者： WANG Chao WANG Pei-fang Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes Hohai University Nanjing 210098 China college of environmental science and Engineering Hohai University Nanjing 210098 China

Based on the analysis of dilution capacity and self-purification capacity of water body, the dilution, dispersion, entrapping and purification principles of pollutants in river system at river network area were discussed in this paper. Also, the one and two dimensional models of water quantity needed for improving water environment quality and pollutant concentrations were developed for rivers and lakes respectively. The calculation method for the quantity of water transfer was given and the forecasting evaluation of the effect of water transfer was carried out. It was took the project, water transfer from Yangtze River to improve the water quality of rivers in Zhangjiagang City, as an example, and changing principles of water quantity and quality were observed in rivers and lakes through site water transfer experiments. The theory of estimating parameters in inverse problem was used to determine parameters in water quantity and quality models. The water quantity and quality coupled models in river system were applied to calculate the minimal water transfer quantity. The theoretical and technical support for the improvement of water environmental quality in Zhangjiagang City and the project ＂water transfer form Yangtze River to Taihu Lake＂ were provided.

关键词： river network dilution purification mathematical models site observation

Hybrid method of limit equilibrium and finite element internal force for analysis of arch dam stability against sliding

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science china(Technological sciences) 2011年第4期54卷 793-798页

作者： BAO TengFei1,2,3,XU BaoSong1,2,3 & ZHENG XueQing1,2,3 1State Key Laboratory of Hydrology-Water resources and Hydraulic Engineering,Hohai university,nanjing 210098,china 2National Engineering Research Center of Water resources Efficient Utilization and Engineering Safety,nanjing 210098,china 3college of Water Conservancy and Hydropower Engineering,Hohai university,nanjing 210098,china State Key Laboratory of Hydrology-Water resources and Hydraulic Engineering Hohai University Nanjing China National Engineering Research Center of Water resources Efficient Utilization and Engineering Safety Nanjing China college of Water Conservancy and Hydropower Engineering Hohai University Nanjing China

A hybrid method of limit equilibrium and finite element internal force for analysis of arch dam stability against sliding is *** finite element internal force method(FEIFM) is used to provide more accurate thrust forces acting on the faces of a slip body,and the limit equilibrium method(LEM) is employed to evaluate the factor of safety of the slip *** method presented can deal with a slip body with large amount of geometrically complex slip *** addition,compared with the traditional LEM,it can meet the balance condition of the forces in the slip *** example shows that the factor of safety obtained by the method presented agrees well with the theoretical solution.A practical example is also presented to demonstrate the application of the method in the stability analysis of an arch dam *** results from the examples show that the method is promising in analysis of arch dam stability against sliding.

关键词： arch dam stability against sliding limit equilibrium method finite element internal force method

New Insights into the Nitrogen Form Effect on Photosynthesis and Photorespiration

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Pedosphere 2007年第5期17卷 601-610页

作者： GUO Shi-Wei ZHOU Yi GAO Ying-Xu LI Yong SHEN Qi-Rong college of resources and environmental sciences Nanjing Agricultural University Nanjing 210095 （China）

Under high light conditions, ammonium nutrition has a negative effect on plant growth. This suggests that the adverse effects of ammonium nutrition on plant growth may be related to carbon gain, photosynthesis, and photorespiration. However, there is no consistent evidence of a specific mechanism that could explain the plant growth reduction under ammonium supply. It is generally accepted that during the light reaction, a surplus of nicotinamide adenine dinucleotide hydrogen phosphate （NADPH） is produced, which is not completely used during the assimilation of CO2, Nitrate reduc- tion in the leaf represents an additional sink for NADPH that is not available to ammonium-grown plants. Nitrate and ammonium nutrition may use different pathways for NADPH consumption, which leads to differences in photosynthesis and photorespiration. The morphological （i.e., cell size, mesophyll thickness, and chloroplast volume） and enzymic （i.e., ribulose-1,5-bisphosphate carboxylase/oxygenase （Rubisco）, phosphoenolpyruvate carboxylase （PEPCase）, and glutamine synthetase/glutamate synthetase （GS/GOGAT）） differences that develop when plants are treated with either nitrate or ammonium nitrogen forms are related to photosynthesis and photorespiration. The differences in photorespiration rate for plants treated with nitrate or ammonium are related to the conversion of citrate to 2-oxoglutarate （2-OG） and photorespiratory CO2 refixation.

关键词： ammonium nitrate nitrogen form photorespiration photosynthesis