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Wang Z.-C.,Jiangxi Provincial Institute of Water science | Li D.-M.,Tianjin University | Hu Y.-W.,Tianjin University
Jisuan Lixue Xuebao/Chinese Journal of Computational Mechanics | Year: 2017

In order to suppress the stress unstability of SPH method, a stress correction algorithm that calculating the tensile and compressive stress with different kernel functions and state equations is proposed. Then an improved Quintic kernel function improve compressive stress stability of SPH model is introduced. The stress correction algorithm increases Bell-Shaped kernel's smooth length to promote the tensile stresses stability. Moreover the stress correction algorithm is applied to simulate oscillation and deformation of a square droplet under weightlessness conditions. Several numerical results of different algorithms are proposed for comparative analysis. In addition, to further verify the algorithm's applicability, this paper simulates a dam break example. Studies show that Improved Quintic kernel function significantly solved particles aggregation problem. The SPH stress correction method can make droplets having more uniform particle distribution and more smooth free surface, effectively improve the stress stability of SPH method as well as the simulation accuracy of free surface flow. © 2017, Editorial Office of Chinese Journal of Computational Mechanics. All right reserved.


Feng L.,Wuhan University | Feng L.,University of South Florida | Hu C.,University of South Florida | Chen X.,Wuhan University | And 5 more authors.
Remote Sensing of Environment | Year: 2011

Using MODIS 250-m resolution data, we developed a novel approach to derive the bottom topography of Poyang Lake, the largest freshwater lake of China (> 3000 km2 at maximum inundation) for every year between 2000 and 2009. The approach differs from other traditional methods (sonar, Lidar, optical inversion, and Radar) but takes advantage of the fast-changing nature of the lake's inundation area. On every image, the water/land boundary is effectively a topographic isobath after correction for the water level gradient. Thus, the ~10/year carefully selected MODIS images provided incremental topographic isobaths, from which bottom topography was derived every year. Such-derived topographic maps were validated using limited historical data and other consistency checks. Most of the lake bottom showed an elevation of 12m to 17m (referenced against the elevation reference of the Woosung Horizontal Zero). Significant inter-annual variability of the bottom topography from 2000 to 2009 was found for some of the lake's bottom, with more areas associated with bottom elevation increases than decreases. The changes and inter-annual variability in the bottom topography were attributed to the combined effect of human activities (e.g., sand dredging and levee construction) and weather events. One example was the increased bottom elevation from 2002 to 2003, which was apparently due to the excessive precipitation in 2002 and the impoundment of the Three-Gorges Dam in 2003. The 10-year record of the bottom topography of this highly dynamic lake provides baseline information to monitor the impact of future engineering and management activities, to estimate the lake's water and sediment budgets, and to aid ship navigation. © 2011 Elsevier Inc.


Gao J.,Tianjin University | Chen Y.,Jiangxi Provincial Institute of Water Science
Advanced Materials Research | Year: 2012

Closed concrete cut-off wall has been widely used in the reinforcement projects of earth-rock dam. However, the research on the cut-off wall was rare. In order to discuss the stress state of the wall under different engineering conditions, a coupled numerical model was established by considering coupled interaction, including contact between wall and dam, and coupling of stress and seepage. Taking the earth-rock dam which built on common foundation for example, the stress distribution of the wall and influencing law of different factors were mainly researched, including elastic modulus of the wall, deformation modulus of the dam filling materials, permeability coefficient of the dam foundation, etc. The conclusions had reference significance for the application and design and calculation method of concrete cut-off wall in the reinforcement projects of earth-rock dam. © (2012) Trans Tech Publications, Switzerland.


Lu J.,Jiangxi Water Resources Institute | Zhong X.,Jiangxi Provincial Institute of Water science | Wu H.,Jiangxi Water Resources Institute | Wu H.,Jiangxi Provincial Institute of Water science | Wang H.,Hohai University
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

The movement of lake sediments under different hydrodynamic conditions was simulated, and vertical distribution characteristics of heavy metals in lake under different hydrodynamic conditions were explored with self-designed circulating flume and sediments sampled from Xingzi section of Poyang Lake. The flume device was composed of inlet tank (0.5 m3), test area (2 m in length, 1 m in width, and 0.5 m in height), outlet tank (0.5 m3), storage tank (1 m3) and pump (maximum flow rate of 100 m3/h). Prior to testing, sediment was spread at the flume bottom, and lightly pressed and flattened to a thickness of 8 cm. After remaining it untouched for 0.5 h, water was added into the device. Water depth in the flume was controlled at 140 cm. Water was pumped from the storage tank into the inlet tank, and flowed through the test area, the outlet tank and eventually returned to the tank. During the test, the flow rate in the flume was gradually increased from 0 cm/s, and its flow rate was set through the control of the gate as 0 cm/s, 5 cm/s, 15 cm/s, 25 cm/s, 35 cm/s, 45 cm/s and 65 cm/s. To ensure that the water flowed through the flume at least once, the testing period was maintained 1 h under each flow rate, and then immediately proceeded to the next flow rate until it reached the maximum flow rate. During the test, the incipient motion characteristics of sediment, including critical motion state, slight motion state and plenty motion state, were initially simulated. The water depth in the flume was divided into four layers. The total heavy metal concentration and dissolved heavy metal concentration were measured at different flow rates and different water depths. In order to minimize deviation, heavy metal concentration was measured three times and the average value was taken under each group of water flow and water depth condition. When the sediment was in critical motion state at flow rate of less than 25 cm/s, a diluted suspension at the sediment surface was appeared with the increase of flow rate. The total heavy metal concentrations were similar at different water depths in this period. When the sediment was in slight motion state at flow rate of 25 cm/s to 50 cm/s, water became turbid, with part of the sediment washed up. Shear stress at sediment surface was obviously larger than that in critical motion state, and the total heavy metal concentrations were increased from water surface to bottom, although it was not obvious. When the sediment was in plenty motion state at flow rate of 60 cm/s to 70 cm/s, a large amount of sediment was washed up, and water became turbid in a short period. Large quantities of heavy metals in the sediment were released into water, and the total heavy metal concentration was increased obviously along the water depth direction. In addition, by analyzing the concentrations of dissolved Cu, Zn, Cd and Pb in each layer with curve fitting method, vertical distribution characteristics of heavy metals under different hydrodynamic conditions were revealed. The basic formula was established between heavy metal concentration and height above sediment surface. The results showed that when the hydrodynamic condition was strong, the concentrations of dissolved Cu, Zn, Pb were increased logarithmically from water bottom to water surface. Furthermore, to detect the applicability of the established formula, the testing results were applied to measurement of Poyang Lake, water samples collected from Poyang Lake Bridge section and Xingzi section at 0.3 m, 0.8 m, 1.3 m and 1.8 m above sediment were used to measure the dissolved heavy metal concentration. Flow rate at the two sections were 39 cm/s, 75 cm/s and 44 cm/s, 68 cm/s, respectively, when the samples were collected. By substituting the measured data into the established formula, the obtained result showed that the relative error between calculation results and measured results was within ±15%. The formula was applicable at flow rate of 65 cm/s to 75 cm/s in lakes with sediment grain size of 50 μm to 200 μm. The established formula was basically reasonable. The device was feasible for the experiment with strong operability. The research results could provide references for revealing heavy metal release characteristics under different water conditions. © 2016, Chinese Society of Agricultural Machinery. All right reserved.


Lu J.,Jiangxi Water Resources Institute | Zhong X.,Jiangxi Provincial Institute of Water science | Wu H.,Jiangxi Water Resources Institute | Wu H.,Jiangxi Provincial Institute of Water science | Wang H.,Hohai University
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2016

To study the release flux of heavy metals in sediment of the lake under different hydrodynamic conditions, an interior experiment was designed and carried out. The experiment aimed to simulate the migration of sediment in the lake and to investigate the release regularity of heavy metals in sediment under different hydrodynamic conditions. The sediment in Xingzi Reach of Poyang Lake was selected as the experiment material and a circulating facility was designed. The circulating facility was composed of an inlet tank (0.5 m3), an experimental tank (2 m×1 m×0.5 m), an outlet tank (0.5 m3), a storage tank (0.5 m3) and a pump. First, sediment had been tiled at the bottom of the experimental tank with the thickness of 8 cm for half an hour. Then water of 30cm deep was filled in three tanks. The experiment was carried out by pumping water into the inlet tank from the storage tank, going through the experimental tank, the outlet tank and finally back to the storage tank. The average flow velocity was controlled at 0 to 5, 15, 25, 35, 45, and 65 cm/s as the highest speed by the gate. The test of each speed maintained 1 hour to ensure the water was circulated through the facility at least once. In this case, the test not only simulated different migration state under different hydrodynamic conditions, which were "stationary state", "slight migration state" and "intense migration state", but also detected the total concentration of heavy metals in water under different flow velocity conditions at the same time. In order to reduced the experimental error, the sample was taken 3 times to calculate an average concentration. Through analyzing varied heavy metal concentration under different hydrodynamic conditions, some conclusions were drawn as below: When flow velocity was less than 25cm/s, heavy metals were released only in interstitial water for not much sediment was suspended and heavy metal concentration was not increased greatly with slight interference; With increasing flow velocity, sediment shifted from "stationary state" to "slight migration state" and the concentration of Cu, Zn, Cd and Pb rose evidently for that much sludge moved up, smaller particle mud of heavy metals went up to overlying water, and large quantity of heavy metals released in interstitial water at the same time; When the flow velocity reached 60-70 cm/s, "intense migration state" was achieved since the movement of mud at the bottom was relatively severe and silt by piece. The concentration of Cu, Zn, Cd and Pb in water and its release flux in sediment speeded up. When flow velocity was 65 cm/s, the density of Cu, Zn, Cd and Pb was 127.16, 220.5, 0.28, 11.07 μg/L respectively. The release flux was calculated by analyzing the concentration changes of Cu, Zn, Cd and Pb in the water under different flow velocity conditions. The relationship between release flux of heavy metals in sediment of the lake (y) and speed (x) was established by linear fitting. The result shows that release flux of Cu, Zn, Cd and Pb in sediment of the lake has an exponential relationship with speed. In addition, to test the applicability of the established related equation, this paper applied the equation to field experiment of Poyang Lake. First, the concentration of heavy metals in Poyang Lake under different hydrodynamic conditions was detected and the velocity was recorded. And then the release flux of heavy metals in Poyang Lake was calculated by referring to the relationship which was established from the interior test. The concentration of heavy metals in Poyang Lake was calculated (that is the calculated concentration) according to the release flux. Finally, the calculated concentration was compared with measured concentration. The result shows that the values between calculated concentration and measured concentration are very close with the error range of 5%-20%, which indicated that the relationship between release flux of heavy metals and speed set in this paper was basically reasonable and could adapt to conditions similar with Poyang lake and the sediment particle size of 50 to 200 μm, of the experimental facility was feasible and operable. The results can provide scientific basis on control and governance of heavy metal pollution. © 2016, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.


Zhang X.-P.,Jiangxi Provincial Institute of Water science | Li R.-F.,Jiangxi Provincial Institute of Water science | Li R.-F.,Donghua University | Lei S.,Jiangxi Provincial Institute of Water science | And 2 more authors.
Procedia Environmental Sciences | Year: 2011

MODIS sensor has a high temporal resolution, spectral resolution, and moderate spatial resolution. The data products are widely used in Large-scale and long period dynamic monitoring of drought. This paper focuses on characters of farming rice dominated in Jiangxi province, and analysis on remote sensing monitoring model and drought monitoring indicators which selection the MODIS data products and drought information related from 2000-2008. Established standard for classification of drought in Jiangxi province, and verified instances of 2003 drought in Jiangxi. This study may have a certain significance to agricultural drought monitoring based on rice planting in southern China, because the correspondence match between the selected TD indices and cloud cover with precipitation and daily maximum temperature evolution curve. © 2011 Published by Elsevier Ltd.


Lei S.,Jiangxi Provincial Institute of Water science | Zhang X.-P.,Jiangxi Provincial Institute of Water science | Li R.-F.,Jiangxi Provincial Institute of Water science | Li R.-F.,Donghua University | And 2 more authors.
Procedia Environmental Sciences | Year: 2011

This paper studies on Poyang Lake natural wetlands. we calculation each month's vegetation area in Poyang Lake that according to cloudless images of MODIS in 2009. And it had a quantitative analysis for the changes of annual by Poyang Lake wetland vegetation with time; space; and the water level. Poyang Lake wetland vegetation is mainly located in the delta of the river lower reaches. The area is changing with month, each year there are two peaks. Before the flood season that the vegetation area increase from spring to April and May. Entering the flood season, the area had been decreased by water level raised; after season, the area increase again with water level dropped. To the autumn and winter, the areas decreased cause of vegetation withered. © 2011 Published by Elsevier Ltd.


Liu J.-T.,Jiangxi Provincial Institute of Water science | Yang Y.-S.,Jiangxi Provincial Institute of Water science | Jiang J.-H.,CAS Nanjing Institute of Geography and Limnology | Gao J.-F.,CAS Nanjing Institute of Geography and Limnology
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2011

Based on the risk analysis of cynaobacteria bloom hazard in Taihu Lake, the index system for the cynaobacteria bloom risk evaluation was constructed. Combined with the concept of risk evaluation, the risk evaluation method was established. On the basis, the hazard risk, exposure risk, vulnerability risk, and comprehensive risk of the nine lake regions in Taihu Lake were evaluated taking 2008 as the base year. The largest risk regions were in northern part of Taihu Lake, especially the Gonghu Lake was the most serious as the water source area. The risk in Zhushan Lake, Meiliang Bay and western coastal was middle for the large hazard risk. In the other regions, the risk in Xuhu Lake, southern coastal and big Taihu Lake was light risk, and there were almost no cyanobacteria bloom outbreak risk for the light eutrophication and large vegetation cover in the southwest regions of Taihu Lake.


Wang Z.Q.,Jiangxi Provincial Institute of Water science | Wang Z.Q.,Nanchang Institute of Technology | Wu X.B.,Jiangxi Provincial Institute of Water science
Applied Mechanics and Materials | Year: 2014

According to the existing arch dam design specification, the temperature load is obtained based on analytic solution of infinite long free plate, it only considers the average temperature and the equivalent linear temperature difference of dam section in operation period, the influence of non-linear temperature difference has not been considered. This kind of simplification has some approximation; especially it can not reflect spatial effect of larger temperature gradient changes in the upstream and downstream water level change area. This paper first takes the free plate as an example, has calculated the temperature field corresponding to analytical method, finite element method, standard method, explains the rationality of using written program to carry on finite element analysis. On this basis, take Xiluodu arch dam as an example, the dam temperature load and temperature stress has been analyzed by using finite element method and standard method, the difference between both has been discussed. © (2014) Trans Tech Publications, Switzerland.


Xiao L.-Y.,Nanchang Institute of Technology | Lan Y.-Y.,Nanchang Institute of Technology | Zhong A.-M.,Jiangxi Provincial Institute Of Water Science
Advanced Materials Research | Year: 2014

In recent years, a large proportion of reservoir works in Jiangxi province have emerged different kinds of new diseases, which not only hold back the benefit but also affect the safety of these projects, to some extent. Based on investigating the present situation of dams in Jiangxi province and analyzing the reasons for deterioration condition in reservoir works, the main disease for hydraulic concrete structure of ill-dangerous dams is divided into several typical types and the characteristics of the existing problems are given as well as some control measures. © (2014) Trans Tech Publications, Switzerland.

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