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10 June 1998, Volume 20 Issue 3
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    Review
    1998, 20(3):  1-8.  doi:10.6052/1000-0879-1999-264
    Abstract ( 1130 )   PDF (405KB) ( 876 )  
    This paper summarized the essential variation of the dynamic factors of the downstream flow and sediment caused by the construction of the ThreeGorges Project, and its main influence on the ecology and environment of the downstream and estuary region by it. Some problems which are difficult to determine at present were analysed in detail to provide a reasonable scientific basis to the multiple development and environment protection of the downstream and estuary region of Yangtze River.
    1998, 20(3):  9-14.  doi:10.6052/1000-0879-1999-265
    Abstract ( 1070 )   PDF (292KB) ( 694 )  
    The middle route south-to-north water transfer project is a magnificent engineering of transcentury.It is characterized by a long route of water diversion and many structures of large size. For this reason, mechanics problems of the project are relatively complex and extremely difficult. Some of them have not yet encountered in the past. This paper described problems such as: hydraulic problems, including ice-hydraulic problems; river dynamic problems, including the engineering measures of main channel cro...
    Application study
    1998, 20(3):  15-16.  doi:10.6052/1000-0879-1999-266
    Abstract ( 1043 )   PDF (251KB) ( 674 )  
    In this paper, the twin-shear stress strength theory is used to analyze the ultimate load of a strength-differential wedge and a solution which takes account of the strength-difference effect and the intermediate main stress effect is obtained. The solution is of importance for giving full play to materials' strength potential ability. Finally, its application ingeotechnical engineering is discussed.
    1998, 20(3):  17-19.  doi:10.6052/1000-0879-1999-267
    Abstract ( 1137 )   PDF (305KB) ( 663 )  
    Internal cracks in grain kernel may occur due to highlevel of thermo-hydro-stresses during drying. Based on this actual problem,the hydro-stress distributions in a Maxwell viscoelastic sphere are studied wheninitial moisture concentration and equilibrium moisture concentration are given, and the variations of the hydro-stress with the lapse of time are discussedas well in this paper.
    1998, 20(3):  20-22.  doi:10.6052/1000-0879-1999-268
    Abstract ( 909 )   PDF (326KB) ( 608 )  
    The fixed transverse vibration under a thermal state of the three parameter foundation is studied using Galerkin principle and the improved KBM method. Through the calculation of examples the rising of temperature is discussed and analyzed, some valuable conclusons are made of the influence under the thermal state of charateristic parameters of the wall of the foundation on its eigen frequencies.
    1998, 20(3):  23-25.  doi:10.6052/1000-0879-1999-269
    Abstract ( 1023 )   PDF (185KB) ( 751 )  
    An approximate calculated formula for σ 0 of a material is provided by means of σ -1 and σ b of the material. Based on the study, the criterion for fatigue strength and yield strength for a member when the stress cyclic character r >0 is also obtained in this paper.
    1998, 20(3):  26-28.  doi:10.6052/1000-0879-1999-270
    Abstract ( 892 )   PDF (270KB) ( 659 )  
    This article describes the fittings of cistern and the application of mechanical principles in various inlet and outlet valves of a cistern. The characteristics of different products are compared from a mechanical view.
    1998, 20(3):  29-30.  doi:10.6052/1000-0879-1999-271
    Abstract ( 1034 )   PDF (211KB) ( 593 )  
    The effects of the shapes and dimensions of table tennis bat on table tennis ball head on impact probability have been investigated by an analytical method of probability function.In view of the fact that the table tennis bat outline is a curve of the equivalent probability,this paper derives a mathematical expression for the outline of the table tennis bat that gives the maximum impact ball probability. The results indicate that the present shapes and dimensions of the table tennis bat need to be improv...
    1998, 20(3):  31-33.  doi:10.6052/1000-0879-1999-272
    Abstract ( 999 )   PDF (246KB) ( 1127 )  
    In this paper it is proposed a complex number method to analyse the movement of plan mechamisms. The advantage of this method is the clear concept and simple operation. The more complecated of mechanism movement, the more obvious of this advantage, it is also very convenient for making computer programm.
    1998, 20(3):  34-35.  doi:10.6052/1000-0879-1999-273
    Abstract ( 887 )   PDF (246KB) ( 517 )  
    The stratum with the largest bearing capacity between coal seam and aquifer is regarded as the key stratum in preventing from water inrush,and it is simplified into a thin plate. Its fracturing span is determined by the plate theory, and is used to appraise the risk of water inrush from floor. The analyses of real examples show that the method is the simple and efficacious.
    1998, 20(3):  36-37.  doi:10.6052/1000-0879-1999-274
    Abstract ( 1193 )   PDF (249KB) ( 517 )  
    In this paper, the smooth blasting rock layer is analyzed. The development of smooth blasting crank, and the fragmentation process of the smooth blasting rock layer are discussed.
    1998, 20(3):  38-40.  doi:10.6052/1000-0879-1999-275
    Abstract ( 1180 )   PDF (245KB) ( 584 )  
    The bifurcation points of airfoil flutter system in incompressible flow are investigated in this paper. The theory of centre manifold is first used to reduce the flutter system to a two-dimensional one. Then the type and stability of the bifurcation points are analyzed by utilizing the method of succeeding function.
    1998, 20(3):  41-42.  doi:10.6052/1000-0879-1999-276
    Abstract ( 1253 )   PDF (273KB) ( 1214 )  
    Waterhammer is simulated by the recently developed lattice Boltzmann method, which is fully parallalled and simple in algorithm, and can be used to treat complex geometries. Basic principles, computing algorithms, and comparisons between results of the LB and the MOC (method of characteristics) are presented. It is shown that the LB method is a feasible approach to simulate hydraulic problems in engineering.
    1998, 20(3):  43-44.  doi:10.6052/1000-0879-1999-277
    Abstract ( 1011 )   PDF (288KB) ( 856 )  
    A detailed examination of the non steady forces (Basset force and added mass force) acted on particles moving in arbitrary flow field is carried out using the typical function method. It is found that Basset force is important for the motion of heavy particles, and that for the motion of light particles, added mass force is dominant while Basset force is negligible.
    1998, 20(3):  45-45.  doi:10.6052/1000-0879-1999-278
    Abstract ( 965 )   PDF (281KB) ( 515 )  
    In this paper, the local hybrid method, combining he moire interferometry experiment with FEM, is used to evaluate the experimental results in interfacal region. The results of local hybrid method is compared with photoelasticity and FEM method.
    1998, 20(3):  46-49.  doi:10.6052/1000-0879-1999-279
    Abstract ( 885 )   PDF (400KB) ( 414 )  
    Based on the third and the fourth strength theory, this paper presents an analytic formula for optimum radius of elastic-plastic juncture in autofrettage technology; influence of autofrettage on stress distribution and load-bearing capacity of a cylinder is studied and optimum pressure in autofrettage technology is obtained.
    1998, 20(3):  50-51.  doi:10.6052/1000-0879-1999-280
    Abstract ( 1104 )   PDF (251KB) ( 623 )  
    An approximate method of plane strain for the dynamic complex stiffness analysis of axial response of single pile is eveloped. A formulation of dynamic complex stiffness matrix of pile foundation is derived and dynamic property of stiffness and resistance of pile foundation is discussed. Then a series of relation curves and conclusions are obtained by comparison and checking with real examples.
    1998, 20(3):  52-53.  doi:10.6052/1000-0879-1999-281
    Abstract ( 1029 )   PDF (216KB) ( 670 )  
    Contact problem is a complex and nonlinear one. A number of difficulties will appear when only numerical or experimental method is adopted to solve it. The mixed method, which combining the finite element method with plane photo elasticity experiment method, is a simple and effect method for solving contact problem.