Papers by Author: Yu Lan Tang

Abstract: This article describes the simulation method of water temperature and the model classification of water quality in lakes and reservoirs, and classic model of ecosystem dynamics of lakes and reservoirs - BA model from the water quality parameters of the relationship between two aspects of the basic equations are introduced. On this basis, establish the eutrophication of ecological models of lakes and reservoirs.

Abstract: The paper introduced the source and harmfulness of heavy metal pollution in water environment and summarized the applications of the chemical method, physiochemical method and biological method in heavy metal pollution of sudden emergency accident. Meanwhile, the heavy metal pollution emergency processing technology of rivers, lakes and other water bodies were elaborated and the emergency engineering technology of heavy metal pollution in rivers and lakes were analyzed. Finally, the application of bioremediation on heavy metal pollution caused by sudden emergency accident was prospected.

Abstract: Abstract.One superior iron and manganese bacteria were separated from the stable operation of porcelain granular BAF filters of removing iron, manganese and ammonia. The bacteria was domesticated at low temperature. By analyzing the sample water containing iron and manganese in the role of iron and manganese bacteria which was not domesticated and domesticated at different temperature, observing the Iron and manganese concentration with time going on, studying the bacteria’s removal of iron and manganese property and the domesticated effect. Studies show that: the selected bacteria with 1% bacterial liquid at proper temperature within 48h ,the removal rate of iron and manganese was 75% and 35% respectively;After domesticated at low temperature, the removal rate of the iron and manganese domesticated bacteria at 10°C was improved 0.4 and 2 times more than the before domesticated; The iron and manganese domesticated bacteria at 10°C did not grow at 4°C,but the bacteria’s removal rate was better than the bacteria cultured at 30°C,and the iron removal rate was improved from 23% to 35%,the manganese removal rate was improved from 5% to 11%.

Abstract: A 3D model of molecular dynamics for nanoceramic SiC is adopted to simulate the hot pressing sintering and preparation process of SiC, and mechanical properties such as density, hardness and elastic modulus are calculated. Finite element model of indentation is established based on the mechanical performance parameters from MD simulation. Conical indenter is adopted in indentation simulation. The FEM simulation results show that: Maximum equivalent stress appears at the place of indenter tip, and equivalent stress curves are appeared hemispherical. As indentation depth increases, the stress increased. As the distance of away from the indenter increases, the displacement in equivalent displacement nephogram gradually decreased until zero. During unloading process, elastic restitution is occurred. The elastic restitution in the area of below the indenter is obviously. Residual stress in the center of indentation is maximal after unloading.

Abstract: In order to extend the preservation time of the ferrate, the experiment was carried out to study the type of strong oxidizer and buffering agent through static comparing test. The orthogonal test determined the best parameters of sulfate type, temperature and the dosage. The result shows that the inhibitory action of Na2S2O8 is the strongest oxidizer, and the temperature had the important role on ferrate stability. The higher temperature, the quicker the ferrate decomposition speed. The Na2S2O8 effect on stability was the best at any temperature and the dosage of Na2S2O8 could be controlled between 0.5% and 1.0%.The carbonate buffering agent could play certain stable effect, the ferrate decomposition is only 7.65% from the 2nd day to the 10th day when the mole ratio of NaHCO3 and NaOH was 2:1 and the density was the ferrate’s 100times.

Abstract: Laboratory-scale tests for removal and recovery of nitrogen and phosphorus in human urine were conducted by magnesium ammonium phosphate precipitation (MAP) method. Proper Na2HPO4•12H2O as a phosphorus source and MgCl2•6H2O as a magnesium source were added to adjust the ratio of Mg2+, NH4+and PO43-. The effects of initial pH, (Mg2+): n (NH4+), n (PO43-) : n (NH4+), temperature, reaction time and stirring speed on removal and recovery of nitrogen and phosphorus in urine were studied by MAP method. Results showed that the optimum experimental conditions were at room temperature, pH, the molar ratio of Mg2+：PO43-：NH4+, reaction time and stirring speed were set 10, 1.2:1:0.9, 30min and 100r/min.

Abstract: Acclimation of short-cut nitrification aerobic granular sludge with aerobic granular sludge and nitrification sludge as seed sludge in a sequencing batch reactor(SBR) by controlling the pH, influent ammonia concentration, temperature and other conditions. Experimental results showed that the short-cut nitrification aerobic granular sludge with high ammonia and COD removal rate (95%) was formed successfully, and SBR can run long-term stably. DO at 6.0~8.0mg/L when the nitrosation rate remained stable at 50% ~ 60%, and lower DO levels within the reactor (2.0~3.0mg/L) nitrosation rates of up to 90%. Mature short-cut nitrification aerobic granular sludge average diameter of 2~3mm in between, MLSS of up to 10.162g/L, SVI minimum up to 22.63ml/g, moisture content is only 81.93%, total nitrogen removal rate of 40%, and carbon-nitrogen removal capability.

Abstract: Cathode catalyst layer plays an important role in PEMFC. Electrochemical reaction in cathode catalyst layer is a control process for the performance in PEMFC. In this paper, oxygen reduction reaction (ORR) is studied by molecular simulations based on a series pathway which consist of four steps. We calculated the free energy of four steps respectively by molecular simulations. Comparing free energy of our steps, we found that the fourth step can release more energy than the other steps. At the same time, we found that the energy released in ORR is decreased with the increase of temperature. The process of the first step in the series pathway release less energy than that of other steps. The results are very helpful for optimization of construction in the cathode and improving performance of PEM fuel cell.

Abstract: A molecular dynamics model was performed to study the proton transport of Nafion series membrane which is often used in low temperature fuel cells. The simulations intents to investigate the microstructure and the phenomenon of the proton transport processing. The model includes all-atom of main and side chains. The force field includes intermolecular Coulomb and Lennard-Jones terms and intra-molecular terms for harmonic bond stretch potentials, harmonic angle bend potentials and cosine terms for the torsions. The simulations were carried out in two cube systems at different temperature where water content differed from 5 and 10 water molecules per acid group in the polymer, respectively. The results showed that proton transport affected with water content by analyses of snap- shots of the MD simulation, the radial distribution functions between the sulfur atoms of SO3− groups, between the oxygen atoms of H3O+ ions, between oxygen atoms of water molecules and Nafion atoms at various stages.

Abstract: The microstructure evolution during sintering and preparation of nanoceramic materials is studied by molecular dynamics (MD) simulation. A 3D model for nanoceramic crystal body including mainly crystal planes of (100) and (110) is developed. This model is used to simulate the hot pressing of nanoceramic, especially for SiC, by rapid heating-up and cooling-down under certain pressure. In this model, the Tersoff potential function is used to simulate the interatomic force between atoms. The microstructure during melting process and crystallizing process are investigated by analyzing energy evolution, pair correlation function and the graph of instantaneous place of the atoms. The results show that the microstructure is amorphous after melting, and crystal planes of (100) and (110) are different in density, melting point and microstructure, showing anisotropy.