淀山湖水环境污染探析及防治对策

淀山湖位于上海市西部,是上海市主要饮用水源地,供水量占上海原水供应量的80％左右,因此湖区所在地被上海市政府划定为黄浦江上游水源保护区,是上海市地表水监测重点。为监测湖水水质,在湖区设立了13个监测点,每月监测一次。根据2001~2008年的水质监测资料,对淀山湖的水质变化情况进行了分析。从时间上看,2001~2004年,淀山湖水质的综合污染指数呈上升趋势,2005~2008年,水质总体上呈逐年改善趋势;从空间上看,水质从优到劣排序为：出水口、湖边、进水口。目前,淀山湖水质恶化态势尚未得到根本扭转。针对淀山湖水质污染的现状、原因、变化趋势、污染特征,提出了保护淀山湖水质的措施。     

SIGMA-COORDINATE NUMERICAL MODEL FOR SIDE-DISCHARGE INTO NATURAL RIVERS

Due to large topography slopes in natural rivers, pollutant concentration embodies a property of three-dimensional distribution when wastewater is discharged from effluents along the bank. With the sigma coordinate along the vertical dimension fitted to both the moving free surface and the bed topography, a three-dimensional numerical model was developed in the present work to address pollutant transport processes in the above-mentioned cases. To avoid the reduction in accuracy caused by spurious diffusion in the case of steep bottom slopes, a formula for horizontal diffusion in the sigma coordinate system was derived. A case study for the side discharge into a straight open-channel flow shows that numerical results are verified well by experimental data. Furthermore, the present model is also verified by the simulation of discharging wastewater from Fuling Phosphorus Factory effluent into the Three Gorges Reservoir and the agreement between the numerical simulation results and field observation data is satisfactory. The change of the mixing zone scope in the water surface versus the layers along the vertical dimension was also discussed in detail. The study shows that a more realistic calculation for pollutant discharge has been provided by the present model than by the depth-average model which predicts an unrealistically smaller mixing zone.     

STRUCTURES OF CONFINED VORTEX BREAKDOWN IN CONSTANT DIAMETER PIPE FLOW

Numerical solutions of three-dimensional, incompressible and unsteady Navier-Stokes equations for constant diameter swirling pipe flows are used to study vortex breakdown, including the detailed flow structures in the bubble domain and the “tail” behind the bubble during the vortex breakdown, and a comparison is made between the numerical solutions and the experimental results.     

NUMERICAL MODELLING OF FREE-SURFACE FLOWS WITH BOTTOM AND SURFACE-LAYER PRESSURE TREATMENT

A new non-hydrostatic numerical model with the three-dimensional Navier-Stokes equations on structured grids was constructed and discussed. The algorithm is based upon a staggered finite difference Crank-Nicholson scheme on a Cartesian grid. The eddy viscosity coefficient was calculated by the efficient k-ε turbulence model. A new surface-layer non-hydrostatic treatment and a local cell bottom treatment were introduced so that the three-dimensional model is fully non-hydrostatic and is free of any hydrostat...     

SOLUTION OF THE ENSO DELAYED OSCILLATOR WITH HOMOTOPY ANALYSIS METHOD

An ENSO delayed oscillator is considered.The El Nino atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions.The conceptual oscillator model should consider the variations of both the eastern and western Pacific anomaly patterns.Using the homotopy analysis method,the approximate expansions of the solution of corresponding problem are constructed.The method is based on a continuous variation from an initial trial to the exact solution.A Maclaurin series expansion provides a successive approximation of the solution through repeated application of a differential operator with the initial trial as the first term.This approach does not require the use of perturbation parameters and the solution series converges rapidly with the number of terms.Comparing the approximate analytical solution by homotopy analysis method with the exact solution,we can find that the homotopy analysis method is valid for solving the strong nonlinear ENSO delayed oscillator model.     

THE INFLUENCE OF DIFFERENT DESIGN PARAMETERS AND WORKING CONDITIONS ON CHARACTERISTICS OF HEAT METERS

In this article,the UDF technology in Fluent software is used to simulate three-dimensional flow fields and to obtain various flow parameters. The standard k-ε model and the RNG k-ε model are both used to calculate the inner flow field of the basal meter,and a comparison of the calculated results between two models shows that RNG k-ε model is more effective for calculations of the inner flow of rotary wing mechanism. The influence of tip clearance on the characteristics of the basal meter is studied. The in...     

EXPERIMENTAL STUDY ON THE MECHANISM OF THE RICHTMYERMESHKOV INSTABILITY AT A GAS-LIQUID INTERFACE

The mechanism of the Richtmyer-Meshkov instability was experimentally studied in a vertical rectangular shock tube. The velocity of the interface driven by the shock wave was measured by a self-designed measurement system, which consists of semiconductor lasers, signal amplification circuits, digital oscilloscope and computer. Tests were carried out at several shock wave Mach numbers. In addition, the movement of the interface and the variation of the mixed zone width with time were recorded by high-speed photography. The experimental results show that the interface velocity increases with the increase of the Mach number, and the distance of the interface's movement and the width of the mixed zone vary with time in a linear relationship.     

NUMERICAL SIMULATION OF A PODDED PROPULSOR IN VISCOUS FLOW

A podded propulsor in viscous flow is numerically simulated in this article.The region of fluid is divided into efficient calculation grids.The pressure and viscous force of blades,pod and strut are obtained as functions of an advance coefficient.The steady result is used as a base in the unsteady simulation to obtain a solution more quickly.The distributions of the thrust and torque fluctuations of the key blade in one revolution are obtained.The calculation results from the mixing plane on steady conditions are compared with those obtained from the sliding mesh model on unsteady conditions.The User-Defined Function(UDF)method is used to simulate the influence of ship hull on the non-uniform wake of the propeller.     

MEASUREMENT OF SOLID SLURRY FLOW VIA CORRELATION OF ELECTROMAGNETIC FLOW METER,ELECTRICAL RESISTANCE TOMOGRAPHY AND MECHANISTIC MODELLING

The study presented here was carried out to obtain the actual solids flow rate by the combination of electrical resistance tomography and electromagnetic flow meter. A new in-situ measurement method based on measurements of the Electromagnetic Flow Meters (EFM) and Electrical Resistance Tomography (ERT) to study the flow rates of individual phases in a vertical flow was proposed. The study was based on laboratory experiments that were carried out with a 50 mm vertical flow rig for a number of sand concentrations and different mixture velocities. A range of sand slurries with median particle size from 212 μm to 355 μm was tested. The solid concentration by volume covered was 5% and 15%, and the corresponding density of 5% was 1078 kg/m³ and of 15% was 1238 kg/m³. The flow velocity was between 1.5 m/s and 3.0 m/s. A total of 6 experimental tests were conducted. The equivalent liquid model was adopted to validate in-situ volumetric solids fraction and calculate the slip velocity. The results show that the ERT technique can be used in conjunction with an electromagnetic flow meter as a way of measurement of slurry flow rate in a vertical pipe flow. However it should be emphasized that the EFM results must be treated with reservation when the flow pattern at the EFM mounting position is a non-homogenous flow. The flow rate obtained by the EFM should be corrected considering the slip velocity and the flow pattern.     

试论开发适合银行销售的保险产品

在银行保险业务中,开发适合银行销售的保险产品是一个关键问题,这也是目前我国银行保险发展过程中急需解决的重要问题之一。要做好产品开发的工作,需要银行和保险公司双方的共同努力,一方面巩固分红险和投资连结险的市场,另一方面要重点开发与银行业务相联系的保险产品,同时也要做好产品开发前的市场细分工作和开发后的营销工作,这样才能开发出能够满足客户需求的保险产品,才能使银行和保险公司的合作达到“双赢”。