圆弧型墙背下的主动土压力研究

基于平面滑裂面假设,采用水平层分析法计算墙背为圆弧型情况下的挡土墙主动土压力及其分布情况,分析了挡土墙与墙后填土的各参数对主动土压力大小及分布的影响。计算结果表明,随着挡土墙倾斜角的减小,土压力分布曲线由凸曲线变成凹曲线。最后通过算例将圆弧型墙背下主动土压力及分布的计算结果与平面墙背下的进行分析对比,结果表明当墙背倾斜...     

从深基坑护壁桩桩身弯矩分析桩侧土压力

根据某高层建筑深基坑护壁桩从实测钢筋应力求得的桩身变矩,用数值分析的方法,对桩侧土压力的分布和大小进行了反分析,所得结果与经典土压力理论有显差别,中用土拱的概念对桩侧土压力的分布进行了解释,并给出了桩侧土压力建议图式。     

TheC k instability of navier-Stokes equation appending polynomials of unknown functions

Applying the theory of stratification, the solution space structure about a class of deformed Navier-Stokes equation isdetermined. It is proved that such kind of equation has no C^k (k≥2) stable solution by the fact that the strate transversale is a null set. Foundation item: the National Natural Science Foundation of China (19971054), Shanghai Natural Science Foundation (99ZA14034) Biography: HE You-hua (1960-)     

Upper bound limit analysis of active earth pressure with different fracture surface and nonlinear yield criterion

Conventional calculations of static and seismic active earth pressures of soils on a retaining wall are formulated assuming the soils obeying a linear Mohr–Coulomb yield criterion. However, experimental evidences show that the strength envelopes of almost all geomaterials are nonlinear in nature over a wide range of normal stresses. In this paper, the strength envelope of the backfill behind a retaining wall is considered to follow a nonlinear yield criterion. A simple method is proposed for calculating the static and seismic active earth pressures acting against a retaining wall using a nonlinear yield criterion. This method is based on the upper bound theorem of limit analysis. Both translational and rotational fracture surfaces are employed in the formulation for calculating active earth pressures. Quasi-static representation of earthquake effects using a seismic coefficient concept is adopted for seismic active earth pressure calculations. Instead of using directly the actual nonlinear yield criterion, a linear Mohr–Coulomb yield criterion, which is tangential to the nonlinear yield criterion, is used to formulate the active earth pressure problem as a classical nonlinear programming problem. A nonlinear sequential quadratic programming algorithm is used to search for the maximum solution. In order to assess the validity of the proposed method, values of active earth pressures for different values of seismic coefficients and nonlinear parameters in the yield criterion are calculated and compared with solutions obtained using an extended Rankine’s active earth pressure theory. For the case of static active earth pressure, the upper bound solutions using the present method with a translational fracture surface are equal to the extended Rankine’s theoretical solutions and are slightly smaller than those obtained using the present method with a rotational fracture surface. For the case of seismic active earth pressure, numerical results obtained using the present method with a rotational fracture surface is very close to the extended Rankine’s theoretical solutions. A study is conducted to investigate the effects of the parameters in the nonlinear yield criterion on the active earth pressures.     

IMPULSIVE CONTROL FOR THE STABILIZATION AND SYNCHRONIZATION OF LUR＇ E SYSTEMS

An impulsive control scheme of the Lur‘e system and several theorems on stability of impulsive control systems was presented, these theorems were then used to find the conditions under which the Lur‘e system can be stabilized by using impulsive control with varying impulsive intervals. The parameters of Lur‘e system and impulsive control law are given, a theory of impulsive synchronization of two Lur‘e system is also presented. A numerical example is used to verify the theoretical result.     

Dynamical Behavior of Viscoelastic Cylindrical Shells Under Axial Pressures

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｏｒｙｏｆｖｉｓｃｏｅｌａｓｔｉｃｉｔｙａｎｄｉｔｓａｐｐｌｉｃａｔｉｏｎｓｈａｖｅｂｅｅｎｂｅｃｏｍｉｎｇａｖｅｒｙａｔｔｒａｃｔｉｖｅｒｅｓｅａｒｃｈｆｉｅｌｄｓｉｎｃｅｖｉｓｃｏｅｌａｓｔｉｃｓｔｒｕｃｔｕｒｅｓｗｅｒｅｗｉｄｅｌｙａｐｐｌｉｅｄｉｎｔｏｖａｒｉｏｕｓｅｎｇｉｎｅｅｒｉｎｇ .Ｂｕｔｔｏｔｈｅａｕｔｈｏｒｓ’ｋｎｏｗｌｅｄｇｅ,ｔｈｅｒｅａｒｅｒａｒｅｆｏｒｐａｐｅｒｓｃｏｎｃｅｒｎｉｎｇｗｉｔｈｄｙｎａｍｉｃａｌｂｅｈａｖｉｏｒｏｆｖｉｓｃｏｅ…     

Modeling the interaction of solitary waves and semi-circular breakwaters by using unsteady reynolds equations

A vertical 2 -D numerical wave model was developed based on unsteady Reynolds equations. In this model, the k-epsilon models were used to close the Reynolds equations, and volume of fluid( VOF) method was used to reconstruct the free surface. The model was verified by experimental data. Then the model was used to simulate solitary wave interaction with submerged, alternative submerged and emerged semi-circular breakwaters. The process of velocity field, pressure field and the wave surface near the breakwaters was obtained. It is found that when the semi-circular breakwater is submerged, a large vortex will be generated at the bottom of the lee side wall of the breakwater ; when the still water depth is equal to the radius of the semi-circular breakwater, a pair of large vortices will be generated near the shoreward wall of the semi-circular breakwater due to wave impacting, but the velocity near the bottom of the lee side wall of the breakwater is always relatively small. When the semi-circular breakwater is emerged, and solitary wave cannot overtop it, the solitary wave surface will run up and down secondarily during reflecting from the breakwater. It can be further used to estate the diffusing and transportation of the contamination and transportation of suspended sediment.     

Noether's theory of mechanical systems with unilateral constraints

Ｎｏｅｔｈｅｒ’ｓｔｈｅｏｒｅｍｒｅｖｅａｌｓｔｈｅｉｎｎｅｒｃｏｎｎｅｃｔｉｏｎｂｅｔｗｅｅｎｔｈｅｃｏｎｓｅｒｖａｔｉｏｎｌａｗｓａｎｄｔｈｅｄｙｎａｍｉｃａｌｓｙｍｍｅｔｒｙｏｆｄｙｎａｍｉｃａｌｓｙｓｔｅｍｓ．Ｉｎｔｈｅｒｅｃｅｎｔｔｗｅｎｔ...     

Modeling and analysis of a coupled rigid-flexible system

ＩｎｔｒｏｄｕｃｔｉｏｎＭａｎｙｍｅｃｈａｎｉｃａｌｓｙｓｔｅｍｓｓｕｃｈａｓｒｏｂｏｔｍａｎｉｐｕｌａｔｏｒ,ｔｕｒｂｉｎｅｂｌａｄｅｓ,ｈｅｌｉｃｏｐｔｅｒｐｒｏｐｅｌｌｅｒａｎｄｍａｎ＿ｍａｄｅｓａｔｅｌｌｉｔｅｗｉｔｈｆｌｅｘｉｂｌｅａｔｔａｃｈｍｅｎｔｓａｒｅｃｏｍｐｏｓｅｄｏｆｒｉｇｉｄａｎｄｆｌｅｘｉｂｌｅｂｏｄｉｅｓ．Ｔｈｅｙａｒｅｃａｌｌｅｄｃｏｕｐｌｅｄｒｉｇｉｄ＿ｆｌｅｘｉｂｌｅｓｙｓｔｅｍｓ．Ｃｏｒｒｅｃｔｐｒｅｄｉｃｔｉｏｎｓｏｆｔｈｅｂｅｈａｖｉｏｒｏｆｆｌｅｘｉｂｌ…     

On the Homoclinic Orbits in a Class of Two-Degree-of-Freedom Systems under the Resonance Conditions

ＩｎｔｒｏｄｕｃｔｉｏｎＴｗｏ＿ｄｅｇｒｅｅ＿ｏｆ＿ｆｒｅｅｄｏｍｓｙｓｔｅｍｓｈａｖｉｎｇｃｕｂｉｃｎｏｎｌｉｎｅａｒｉｔｉｅｓａｒｅｅｘｔｅｎｓｉｖｅｌｙｕｓｅｄｉｎｐｈｙｓｉｃｓ,ｍｅｃｈａｎｉｃｓ.Ｆｏｒｅｘａｍｐｌｅ :ｔｈｅｌａｒｇｅ＿ａｍｐｌｉｔｕｄｅｖｉｂｒａｔｉｏｎｓｏｆｓｔｒｉｎｇｓ,ｂｅａｍｓ,ｍｅｍｂｒａｎｅｓａｎｄｐｌａｔｅｓ ,ｄｙｎａｍｉｃｖｉｂｒａｔｉｏｎ＿ｉｓｏｌａｔｉｏｎｓｙｓｔｅｍｓ ,ｄｙｎａｍｉｃｖｉｂｒａｔｉｏｎａｂｓｏｒｂｅｒｓ,ｔｈｅｍｏｔｉｏｎｏｆｓｐｈｅ…     

RENEWAL OF BASIC LAWS AND PRINCIPLES FOR POLAR CONTINUUM THEORIES (Ⅳ)——SURFACE COUSERVATION LAWS

The purpose is to reestablish rather complete surface conservation laws for micropolar thermomechanical continua from the translation and the rotation invariances of the general balance law. The generalized energy-momentum and energy-moment of momentum tensors are presented. The concrete forms of surface conservation laws for micropolar thermomechanical continua are derived. The existing related results are naturally derived as special cases from the results proposed in this paper. The incomplete degrees of the existing surface conservation laws are clearly seen from the process of the deduction. The surface conservation laws for nonlocal micropolar thermomechanical continua may be easily obtained via localization. Contributed by DAI Tian-min, Original Member of Editorial Committee, AMM Foundation items: the National Natural Science Foundation of China (10072024); the Research Foundation of Liaoning Education Committee (990111001) Biography: DAI Tian-min (1931 ~)     

On the stability of general Navier-Stokes type equation

Ｉｎｔｈｉｓｐａｐｅｒ,ｗｈａｔｗｅｄｉｓｃｕｓｂｅｌｏｎｇｓｔｏａｓｔａｂｉｌｉｔｙｐｒｏｂｌｅｍａｂｏｕｔｔｈｅｓｅｃｏｎｄｃｌａｓｇｅｎｅｒａｌＮａｖｉｅｒ＿Ｓｔｏｋｅｓｅｑｕａｔｉｏｎｓ．Ｉｔｔｏｕｃｈｅｓｓｏｍｅｉｍｐｏｒｔａｎｔｐｒｏｂｌ...     

PREDICTION OF MODE Ⅰ CRACK PROPAGATION DIRECTION IN CARBON-FIBER REINFORCED COMPOSITE PLATE

A newly developed Z fracture criterion for the composite materials was introduced, the new concepts of in-plane average strain, in-plane dilatational strain energy density factor and reciprocal characteristic function were presented. Many experimental results show that the Z fracture criterion can be well used to predict the crack propagating direction for mode f crack in carbon-fiber reinforced composite laminates.     

New method to option pricing for the general black-scholes model—An actuarial approach

Using physical probability measure of price process and the principle of fair premium, the results of Mogens Bladt and Hina Hviid Rydberg are generalized. In two cases of paying intermediate divisends and no intermediate dividends, the Black-Scholes model is generalized to the case where the risk-less asset (bond or bank account) earns a time-dependent interest rate and risk asset (stock) has time-dependent the continuously compounding expected rate of return, volatility. In these cases the accurate pricing formula and put-call parity of European option are obtained. The general approach of option pricing is given for the general Black-Scholes of the risk asset (stock) has the continuously compounding expected rate of return, volatility. The accurate pricing formula and put-call parity of European option on a stock whose price process is driven by general Ornstein-Uhlenback (O-U) process are given by actuarial approach. Foundation items: the National Natural Science Foundation of China (69972036); the Natural Science Foundation of Henan Education Committee (1999110010) Biography: YAN Hai-feng (1964∼), Associate Professor, Doctor (E-mail: yhaif@263.net)     

MIXED FINITE ELEMENT METHODS FOR THE SHALLOWWATER EQUATIONS INCLUDING CURRENT AND SILTSEDIMENTATION （Ⅱ）——THE DISCRETE-TIMECASE ALONG CHARACTERISTICS

The mixed finite element(MFE) methods for a shallow water equation systemconsisting of water dynamics equations, silt transport equation, and the equation of bottomtopography change were derived. A fully discrete MFE scheme for the discrete-time alongcharacteristics is presented and error estimates are established. The existence andconvergence of MFE solution of the discrete current velocity, elevation of the bottomtopography, thickness of fluid column, and mass rate of sediment is demonstrated.     

A NOTE ON BIFURCATIONS OF u″+μ(u-uk)=0(4≤k∈Z+)

Bifurcations of one kind of reaction-diffusion equations, u″+μ(u-u^k)=0(μ is a parameter,4≤k∈Z⁺), with boundary value condition u(0)=u(π)=0 are discussed. By means of singularity theory based on the method of Liapunov-Schmidt reduction, satisfactory results can be acquired.     

A study on the mechanism of high-lift generation by an airfoil in unsteady motion at low reynolds number

The aerodynamic force and flow structure of NACA 0012 airfoil performing an unsteady motion at low Reynolds number (Re=100) are calculated by solving Navier-Stokes equations. The motion consists of three parts: the first translation, rotation and the second translation in the direction opposite to the first. The rotation and the second translation in this motion are expected to represent the rotation and translation of the wing-section of a hovering insect. The flow structure is used in combination with the theory of vorticity dynamics to explain the generation of unsteady aerodynamic force in the motion. During the rotation, due to the creation of strong vortices in short time, large aerodynamic force is produced and the force is almost normal to the airfoil chord. During the second translation, large lift coefficient can be maintained for certain time period and , the lift coefficient averaged over four chord lengths of travel, is larger than 2 (the corresponding steady-state lift coefficient is only 0.9). The large lift coefficient is due to two effects. The first is the delayed shedding of the stall vortex. The second is that the vortices created during the airfoil rotation and in the near wake left by previous translation form a short “vortex street” in front of the airfoil and the “vortex street” induces a “wind”; against this “wind” the airfoil translates, increasing its relative speed. The above results provide insights to the understanding of the mechanism of high-lift generation by a hovering insect. The project supported by the National Natural Science Foundation of China (19725210)     

ON THE WELL POSEDNESS OF INITIAL VALUE PROBLEM FOR EULER EQUATIONS OF INCOMPRESSIBLE INVISCID FLUID(Ⅱ)

The solvability of the Euler equations about incompressible inviscid fluid based on the stratification theory is discussed. And the conditions for the existence of formal solutions and the methods are presented for calculating all kinds of ill-posed initial value problems. Two examples are given as the evidences that the initial problems at the hyper surface does not exist any unique solution. Foundation item: the National Natural Science Foundation of China (19971054) Biography: Shen Zhen (1977−)     

Uniform Analytic Construction of Wavelet Analysis Filters Based on Sine and Cosine Trigonometric Functions

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ1 .1ＩｎｔｒｏｄｕｃｔｉｏｎｏｆｂａｃｋｇｒｏｕｎｄＷａｖｅｌｅｔａｎａｌｙｓｉｓａｎｄｉｔｓａｐｐｌｉｃａｔｉｏｎｓｈａｖｅｂｅｃｏｍｅｏｎｅｏｆｔｈｅｆａｓｔｅｓｔｇｒｏｗｉｎｇｒｅｓｅａｒｃｈａｒｅａｓｉｎｒｅｃｅｎｔｙｅａｒｓ[1- 9].Ｅｓｐｅｃｉａｌｌｙ ,ｔｈｅｗａｖｅｌｅｔｔｒａｎｓｆｏｒｍｓｂａｓｅｄｏｎｏｒｔｈｏｎｏｒｍａｌｂａｓｅｓｏｆｃｏｍｐａｃｔｌｙｓｕｐｐｏｒｔｅｄｗａｖｅｌｅｔａｒｅｗｉｄｅｌｙｕｓｅｄｉｎｉｍａｇｅｃｏｍｐｒｅｓｓｉｏｎ ,ｃｏｍ…