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10 December 2003, Volume 25 Issue 6
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    Application study
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-225
    Abstract ( 2109 )  
    This paper verifies an expression, which is rarely mentioned in textbooks, relating the results of 3-point and 4-point bending tests of ceramic materials on fracture strength with the experimental data obtained by Katayama. The expression is shown to be of satisfactory accuracy. The load factor for 4-point bending test, whose derivation is usually not included in textbooks, is also derived in this paper.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-247
    Abstract ( 1023 )  
    Instability destruction of bluff rock slope is closely related to the creep of rock. With a given load, the delayed instability occurs after a period of time. By taking account of creep of rock and using the beam-pole model under the action of gravity, the utmost height of bluff rock slope for different rheology models is derived.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-253
    Abstract ( 1207 )  
    This paper studies the buckling of the Euler's column with large deflection. By combining the linearization of the governing equation with the method of harmonic balance, we have established analytic approximate formulas for the buckling load and the largest deflection of the column. These formulas are valid for small as well as large deformation of the column.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-264
    Abstract ( 1012 )  
    The rectangular beam with dual surface bonded piezoelectric actuators can achieve a pure bending deformation by an external electric field. The strain distribution of the actuators and the beam are analyzed and based on the analytical expressions of strains, the directional attached piezoelectric elements, instead of the conventional attached piezoelectric elements, are used as actuators to reduce their effective transverse stiffness and enhance the actuating effectiveness. In the end, the deformations of two beams with directionally attached piezoelectric elements and the conventional piezoelectric elements are compared by static experiments.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-289
    Abstract ( 935 )  
    The runner-system design is of great importance for a successful injection molding process, particularly, for a family mold with multiple cavities. This paper presents a methodology for automatically balancing multi-cavity injection molds with the aid of flow simulation. After the runner and cavity layout have been designed and the gate size decided, one can adjust runner size iteratively, based on the outputs of flow analysis. A three-cavity family mold is used to illustrate this methodology.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-308
    Abstract ( 957 )  
    The formula for calculating the incipient motion condition of non-uniform sediment has been established by considering the equivalent grain and the relative exposure degree. The results show that the coefficient of the formula is not a constant but varies in a range with the diameter, relative exposure degree and incipient status of grain. The formula for uniform sediment has also been obtained, with the coefficient in a range. The domain of coefficient value calculated in the formula has been verified by using other coefficient data. The results show that the equivalent grain can reflect the characteristics of the sediment incipient motion.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-324
    Abstract ( 1031 )  
    In this paper, the experiments of fuel-air mixture explosion were carried out in a 7.2\,m$^{2} \times 600$\,m real scale tunnel to study the variation and propagation of the pressure and flame in explosion. The relations among the compositions of mixture, boundary conditions, turbulence, combustion and pressure have been obtained.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-330
    Abstract ( 948 )  
    A system to monitor impact forces on piezoelecric smart structures is constructed. The signals of the impact stress wave in time domain were transformed into momentary sequential time signals using Hilbert transform. Neural networks were established to extract different characteristics from these signals for automatic identification of impact location. Experimental results show that the method enjoys good accuracy and stability, which may find applications in the health monitoring of laminated structure damages caused by not very energetic impacts.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-333
    Abstract ( 1121 )  
    Dye coating is the key part of the replication process of recordable optical discs. A simplified model of the coating process is given on the basis of experiments and the dye coating process is studied with the rotating disk theory. The motion equation, boundary equations and continuity equation of flow for the dye film are derived, taking into account the topography on the substrate and the interface slip between liquid and substrate. The governing equation is finally obtained.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-335
    Abstract ( 1157 )  
    In this paper, the carbon steel samples with three kinds of pre-strains were treated by aging, and the bending fatigue test were carried out on these samples. The results show that the fatigue limit of the materials is affected by the pre-strain and the temperature of the strain aging. When the fatigue limit is the maximum, the optimal temperature of the strain aging may decrease with the increase of the pre-strain.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-368
    Abstract ( 1204 )  
    Parameter uncertainty of structural systems is inherent in most engineering problems. It is necessary to study the reliability of uncertain systems. Frequency analysis is important for reliability study of dynamically uncertain structures. In this paper, the criterion is used that the difference between the natural frequency and driving frequency should be less than a specific value. The reliability mode and the safety probability of the random axial vibration systems of rods are defined as a series mode, and the frequency reliability analysis method for avoiding the resonanse is proposed. The quasi-failure analysis method for resonant problem of the random axial vibration systems of rods is studied.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-384
    Abstract ( 1105 )  
    The equilibrium equation of a catastrophe model can describe the jumping behavior of a pole, when there is a tiny displacement at the equilibrium location. The method can also be applied to the jump of other elastomers.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-397
    Abstract ( 1020 )  
    The paper presents a successful numerical simulation of the stone tongue formation in blasting toe-shooting by distinct element method, and an analysis of the numerical simulation results.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2002-449
    Abstract ( 1371 )  
    The three-dimensional state equation was derived for a cylindrically orthotropic piezoelectric body with radial polarization. The layerwise method was employed to transform the state equation with variable coefficients to that with constant coefficients and the state variable solution was obtained. The free vibration problem of a fluid-filled multi-layered piezoelectric cylindrical shell was then analyzed. Exact form of frequency equation was presented and numerical results were obtained.
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2003-081
    Abstract ( 1332 )  
    Overtaking between two vehicles on a highway is one the most basic processes. Traditional modeling is not simple enough. In this paper, the deflection curve of a beam of fixed ends is used to represent the speed-time relation of the faster vehicle. In this way, a mesh-less model is found. Compared with a traditional model, useful results can be obtained. The beam model is applied in a realistic case and the calculated results agree with observation.
    Education Study
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2003-105
    Abstract ( 1324 )  
    Vascular diseases due to atherosclerosis have become a major cause of human mortality and morbidity in modern society. Although atherosclerosis is a multifactor disease, the localization of this disease strongly suggests the involvement of local hemodynamics in the vascular system. In past years, researchers have mainly focused their attention to the effects of stresses, especially the flow-induced wall shear stress, on the pathogenesis of atherosclerosis. In this review, the hemodynamic factors involved in atherogenesis were discussed, and a flow-dependent concentration polarization hypothesis was proposed to explain the localization of atherogenesis.
    Application study
    2003, 25(6):  0-0.  doi:10.6052/1000-0992-2003-427
    Abstract ( 1285 )  
    The invention of the airplane was a milestone in mankind's history. It has tremendously changed human society. It revolutionized the way of travel and commerce; redefined the mode of wars; fueled the progress of science and technology. Aviation and airplane are, and will continue to be, one of the mankind's most significant accomplishments. This paper reviews the evolution of technology of centennial development of airplane, and emphatically points out that aerodynamics has play an important role in the development of aviation. Finally, the paper looks forward to new generation of airplanes in the future.