长三角地区经济一体化发展中的外汇管理对策研究

本文在分析长三角地区经济一体化发展与外汇管理关系和现状的基础上,论述了现阶段推进长三角地区经济一体化发展中外汇管理面临的突出问题,并提出了外汇管理的总体应对规划和近期的对策建议.     

NUMERICAL STUDY OF PARTICLE DISTRIBUTION IN THE WAKE OF GAS-PARTICLE TWO-PHASE FLOWS PAST A CIRCULAR CYLINDER AT HIGH REYNOLDS NUMBER

1. INTRODUCTION Particle ladengasflowspastcircularcylinders areoftenencounteredinindustrial,environmental andenergy relatedprocesses.Becausethegas flowspastcircularcylindersarecharacterizedby thedevelopmentofwakevortices,itwouldsuffice tosaythatunderstandingthemechanismofparti cledistributioninthewakeofcircularcylindersis crucialforreliablepredictions.Thenumericalstudiesofparticledispersioninplanemixinglay ers,planjets,andsprayshavebeenmadeexten sively,anditwasfoundthatthelargeorganized…     

TIDAL CONSTITUENTS IN THE BOHAI AND YELLOW SEAS FROM AN ADJOINT NUMERICAL MODEL WITH TOPEX／POSEIDON DATA

1. INTRODUCTION TheBohaiandYellow(hereafterreferredto asB Y)seas,whichhavebeenwidelyresearched (suchasQiaoetal.[1],Huetal.[2],Pangetal.[3] andsoon),areconsecutivesemi enclosedshallow waterareaswiththemaximumdepth140m.Tides arethemaincontributortooceandynamics.Be causeofthecomplexcoastlinesandbathymetry, thelargedifferenceofdynamics,thelittlespatial scaleoftidesandtheobviousshallowwatercon stituents,itisatypicalareatoinvestigatetides. ManyworkshavebeendoneforthetidesofBYseas.Fang[4]h…     

APPLICATION OF VOF TECHNIQUE TO CHANNEL IMPROVEMENT FOR PANJIATAI SHOAL IN THE YELLOW RIVER

In this paper, Volume Of Fluid (VOF) technique is used to simulate the free surface and the flow field affected by the groynes in the experimental flume and the natural river. A series of flume experiments are carried out. According to the orientation of groynes, angles from the flow direction to the axis of the groyne used in the experiments are assorted into obtuse angle, right angle, and acute angle as well. For each arrangement option, flow conditions are classified as the submerged and the non submerged one. Velocities and the water level affected by single groyne or double-groyne are measured. The calculated results are agreement well with the experimental data. Because of the high demands in the mesh quality and the computer capability, the VOF technique is seldom used to simulate the natural river. In this paper, the VOF technique is also used to simulate the Panjiatai Shoal of 2km long, one of the important improvement reaches in the Yellow River. Two improvement schemes are compared and analyzed, and the better one is recommended.     

SECOND-ORDER DRIFT FORCES AND MOMENTS BETWEEN TWO SUBMERGED BODIES IN WAVES ON 3D METHOD

Two near field methods, namely the integral method and differential method, were presented for giving second-order mean drift forces and moments between two fixed submerged bodies in regular waves. For the integral method, with a series of mathematical manipulations, second order drift forces and moments could be easily expressed by distributed sources which could be calculated by source distribution techniques with the assumption that the amplitude of ship motions are small on the basis of the linear 3D frequency theory. For the differential method, drift forces and moments could be expressed by the derivative of velocity potential with respect to space coordinate. Because two bodies would behaveas a single body while the clearance is very large, the numerical results of one sphere in such case were given and compared with analytical results of a single sphere which does not involve the effect of free surface. When submerged depth becomes enough large, a good agreement can be reached. Then the integral method was used to predict the second order drift forces and moments of two submerged spheres and spheroids with a small lateral separation distance in waves compared with the numerical results obtained by the differential method and they agree well. By comparison, it indicates the interaction effects between two submerged bodies have a profound influence on the drift forces and moments. In this paper, the forward speed effect on submerged spheres was also considered.     

THRESHOLD CONDITION FOR CHOCKING IN OPEN CHANNELS AND EXCAVATION OF TAILRACE

On the basis of energy and continuity equations a general threshold condition for chocking in open channels is obtained and a representation in terms of the Froude number at the upstream section and other parameters is given to predict whether the chocking phenomenon occurs or not at the downstream section. From the general threshold condition for chocking the limit contraction ratios of the channel width are introduced for both with and without the energy losses and a criterion for excavation of the tailrace to avoid chocking is derived. An example shows that using these criterion and the representation proposed for calculating flow depth it is very easy to determine the scheme of the excavation of the open channels.     

INFLUENCE OF GAPS BETWEEN 3-D MULTIPLE FLOATING STRUCTURES ON WAVE FORCES

In the present investigation, influence of gaps between multiple floating structures on wave forces is examined. Strong and complicate hydrodynamic interactions between the floating bodies are observed and the numerical computations have proved the existence of the sharp peak force response on each floating body at some special resonant wave numbers. The resonant wave number is also proved to be around kL =nπ(n = 1, 2, …, ∞) with a corresponding frequency shift. A small yet finite gap width will also give influence on the resonant frequency and resonant amplitude of the wave forces, but when the distance between two aligned boxshaped floating bodies becomes big enough, the hydrodynamic interaction can be neglected. The strong hydrodynamic interaction feature has its own important practical significance for the design of module structures and the links (connection) in the whole floating body system. Moreover, the importance is closely related to the hydro-elasticity analyses of a multiple box-shaped floating body system, in which local loads may be as important as the integrated loads.     

NUMERICAL RESEARCH ON UNSTEADY SHIP WAVE-MAKING PROBLEMS IN TIME-DOMAIN

A time-domain Kelvin source high-order panel method based on NURBS is developed and applied to solve the unsteady wave-making problems. Numerical results of instant wave resistance and free surface elevation are presented and compared with the availaby results by other authors, for submerged spheroid and sphere beneath the free surface and for surface ship of Wigley models moving with unsteady speed,The agreement is satisfying.     

CONTINUOUS WAVELET TRANSFORM OF TURBULENT BOUNDARY LAYER FLOW

The spatio-temporal characteristics of the velocity fluctuations in a fully-developed turbulent boundary layer flow was investigated using hotwire. A low-speed wind tunnel was established. The experimental data was extensively analyzed in terms of continuous wavelet transform coefficients and their auto-correlation. The results yielded a potential wealth of information on inherent characteristics of coherent structures embedded in turbulent boundary layer flow. Spatial and temporal variations of the low- and high- frequency motions were revealed.