Applied Mechanics and Materials Vols. 256-259

Abstract: In order to identify the main factors causing the changes of groundwater quality in major cities of Xinjiang and provide the basis for the prevention and control of groundwater pollution, the monitoring statistics of 17 groundwater samples from the same positions or similar positions in nine major cities of Xinjiang in April-June 2003 and in October-November 2011 are used to classify the groundwater quality of the nine cities in 2003 and 2011 by the “one vote veto” system. The groundwater quality is evaluated with city as the basic unit and according to Quality Standard for Groundwater (GB/T 14848-93). Meanwhile, the changing trend of the major ions in the groundwater is analyzed. The results show: the overall quality of the groundwater of each city was good in 2003 but deteriorated seriously in 2011; Urumqi and Shihezi were the cities where the groundwater quality was seriously deteriorated; the concentrations of most ions and other quality indices in the groundwater all presented a rising trend

Abstract: The multi-objective decision methodology is employed to identify the water resources sustainable utilization (WRSU) mode in Dianchi basin, Kunming. The regional water resources development and utilization is treated as a continuous process for a long-term span. a multi-objective decision model of WRSU is established, which pursues the main objectives including economic growth, environmental improvement and social development and subjects them to the carrying capacity of water resources and the dependant relation of economic, environmental and social development on water resources. The time-varying dynamic evolution characteristics of the trade-off rate between the objectives are analyzed according to decision-makers’ different preference structures during the process of water resources utilization. In the light of Dianchi basin reality, the preferred program of WRSU in the basin is obtained and the coordination between the objectives of WRSU is revealed. A feasible and valid approach is proposed for the sustainability identification and appraisal of water resources utilization.

Abstract: The paper analyzes the research status of shallow salt groundwater at home and abroad and summarizes the research results. It studies on hydrogeochemistry action and variation of hydrogeology parameters which aparts are weak link, and then describes evolution and formation of salt water. In accordance with the principle of environment sustainability, to exploit and utilize water resources reasonably as well as completely improve salt water are mainly emphasis. Future research direction on shallow salt groundwater inland is proposed to urge the research effort to develop to new depth and width.

Abstract: In this paper, we use 3D time-averaged equations and the 3D k-ε turbulence model to numerically simulate the flow in a horizontal sedimentation tank. The PISO algorithm is used to couple velocity and pressure. The results show that the model can provide a reference in designing sedimentation tanks.

Abstract: In this paper, a numerical two-fluid flow model combining with the Realizable k–ε turbulent model for compressible viscous fluid is presented for the computation of flow characteristics in an aeration tank; and the equations are solved with the finite volume method. A multigrid technique based on the full approximation storage (FAS) scheme is employed to accelerate the numerical convergence. The numerical results for velocity and turbulent kinetic energy distribution in the aeration tank are obtained. It is shown that the Computational Fluid Dynamics (CFD) is a valuable tool to analyze the interaction of flow field and aeration.

Abstract: The periodicities of the annual maximum and minimum runoff time series at Datong hydrological station in the Yangtze River（P. R. China）were analyzed, according to the data from 1950 to 1995. The runoff of Datong hydrological station can be used to estimate the water discharges into the sea from the Yangtze River in a certain degree as there is no branch inflow from Datong station to the Yangtze Estuary. Two independent techniques were used in the analysis of time series: the conventional periodogram and the maximum entropy spectral analysis. The results reveal that the periods obtained in the time series at Datong station are related to the rainfall characteristics of the Yangtze River to a great extent. The long periods that are more than 10 years may be related to some climatic factors which are influenced by the solar activities. The short periods that are less than 10 years may be related to some factors which are affected by oceanic tides or human activities. The obtained periods not only reflect the periodicity characteristics of the water discharges into the sea from the Yangtze River, but also provide scientific evidence for the study of evolution of Datong reach of the Yangtze River.

Abstract: This paper introduces development of the agent construction system in China and overview of the South-to-North Water Diversion Middle Route Project. The current practical application of three management modes of direct management，agent construction system(ACS) and commissioning system in the Beijing-Shijiazhuang section of the South-to-North Water Diversion Middle Route Project is analyzed, and some of the advantages of the ACS is pointed out. In the process of practice of the ACS, several existent key problems are discussed, such as the choice of the agent construction units, defective section division of the agent construction, unclear responsibilities, rights and obligations of the agent construction unit, the unreasonable agent construction cost and so on. Then,some constructive improvement measures are put forward , such as to improve the supervision and inspection mechanism, to issue the regulations and standard contract templates of agent construction, to establish incentive and punishment mechanism, to strengthen qualification management of the agent construction unit and to actively cultivate the project management company.Through exploration and analysis on the ACS of the concrete practice and applied research, a reference is provided for further promotion and application of the ACS in the hydraulic engineering in China and the direction of development is indicated.

Abstract: In this paper the numerical simulation of a free surface flow over a vertical weir with in turns of a scour pool and a small hump weir is presented. Since in this case few of calculative examples adds scour pool and small hump weir in the model, it is meaningful to compute this example using a numerical software which is named Fluent 6.3. The numerical method used consists of Navier–Stokes turbulence solver and k-ε model together with a VOF method and PISO algorithm in pave meshes. Thus, the sketches of flow fields on each typical time point and velocity distributions on each section on 16s are provided to describe flow field accurately. A very good quantitative consequence which accords with hydraulics theoretical analysis has been obtained.

Abstract: This paper is concerned with a gas-liquid two-phase model combining with the k–ε turbulent model for numerical simulation of 3D flood waves due to complete or partial dam-break. The flow equations are solved with the finite volume method and solved by the pressure-correction algorithm of the SIMPLE-type. The free fluid surface is simulated by the the volume of fluid(VOF) method. The comparisons with other numerical results show that the proposed method is accurate, reliable and effective in simulation of dam-break flood waves.

Abstract: There are a large number of natural gas pipelines in East Sichuan. In order to prevent these natural gas pipelines from being corroded, they all use cathodic protection, but in terms of pipeline protection potential, the effect is unsatisfactory. Based on pipeline protection potential data collection, this paper carried out field investigation on anode beds, reference electrodes and management mode, analyzed the common problems of cathodic protection systems and put forward rectification suggestions.