应用数学和力学

On the Sensitive Dynamical System and the Transition from the Apparently Deterministic Process to the Completely Random Process

Yue Zeng-yuan, Zhang Bin

1985, 6(3): 197-212.

Abstract(1557) PDF(430)

Abstract:
The detailed analysis of the dynamical process of coin tossing is made. Through calculalions, it is illustrated how and why the result is extremely sensitive to the initial conditions. It is also shown that, as the initial height of the mass center of the coin increases, the final conflguration, i.e. "head" or "tail", becomes more and more sensitive to the initial parameters(the initial velocity angular velocity,and the initial orientation). the coefficient of the air drag, and the energy absorption factor of the surface on which the coin bounces. If we keep the "head" upward initially hut allow a small range for the change of somt other initial parameters, the frequency that thefmal conflguration is "head", would be I if the initial height h of the mass center is sufficiently small, and would be close to 1/2 if h is sufficiently large. An interesting question is how this frequency changes continuously from 1 to 1/2 as h increases. Detailed calculations show that such a "transition" is very similar to the transition from laminar to turbulent flows. A basic difference between the "transition stage" and the"completely rondom stage" is indicated: In the "completely rondom stage", the deterministic process of the individual case is extremely sensitive to the initial conditions and the dynamical parameters. but the statistical properties of the ensemble are insensitive to the small changes of the initial conditions and the dynamical parameters. On the contrary, in the "transition stage", both the deterministic process of the individual case and the statistical properties of the ensemble are sensitive to the initial conditions and the dynamical parameters. The mechanism for this feature of the "transition stage" is the existence of the "long-train structure" in the parameter space. The illuminalions of this analysis on some other rondom phenomena are discussed.

The Spectral Problem of Poiseuille Flow

Dong Ming-de

1985, 6(3): 213-218.

Abstract(1588) PDF(442)

Abstract:
For Poiseuille flow the Orr-Sommerfeld equation is solved exactly. Regular solutions are obtained, thereby eigenvalue equation can be analyzed analytically and explicitly. The bifurcation solutions will be discussed subsequently.

Theorem of the Uniqueness of Displacement and Stress Fields of Line-Loaded Integral Equation Method

Yun Tian-quan

1985, 6(3): 219-222.

Abstract(1936) PDF(441)

Abstract:
According to Fredholm's theorem, this paper proves that due to the virtual fundaemental loods which satisfy the boundary conditions and being distributed outside the elastic body occupied region the displacement and stress fields in the elastic body occupied region are unique. This theorem forms a theoretical basis of the applications of the line-loaded integral equation method.

New Formulations of the Second Fundamental Problem in Plane Elasticity

Lu Jian-ke

1985, 6(3): 223-230.

Abstract(1702) PDF(552)

Abstract:
Some general formulations of the second fundamental problem in plane elasticity are proposed here when the displacements given on the closed boundary contours of a multi-connected elastic region are relative to certain rigid motions which are different to each other for different boundary contours. In such case, it is proved that, for the unique existence ofsolution, there must be given in addition to the principal vector and the principal moment of the extemal forces on each boundary contour. A method of solution is given also together with some illustrative examples.

Forced Vibrations of Elastic Shallow Shell Due to the Moving Mass

Cheng Xiang-sheng

1985, 6(3): 231-238.

Abstract(1598) PDF(541)

Abstract:
This paper discusses the forced vibrations of the elastic shailow shell due to the moving moss by means of the variational method. In the text mentioned above a series of problems such as the forced vibrations, resonance conditions and critical speed and so forth.

Elastic-Plastic Analysis of Cylindrically Orthotropic Composite Thick-Walled Tube

Zhou Ci-qing, Qiu Yi-yuan

1985, 6(3): 239-246.

Abstract(1633) PDF(455)

Abstract:
In the present paper, Tsai-Hill Yield Criterion in a state of plane strain is derived for incompressible and compressible materials respectively. The elastoplastic stress and displacement fields of cylindrically orthotropic composite thick-walled tube under uniform radial pressure are studied. The formulas of the yield pressure, Iimit pressure and region of shakedown are obtained.

Application of Shooting Methods for Two-Point Boundary Value Problems of Ordinary Differential Equations with Parameters in Hydrodynamics

Guo Ben-tie, Ying Yu-yan, Chen Bang-guo, Xu Bao-zhi

1985, 6(3): 247-254.

Abstract(1961) PDF(518)

Abstract:
In this paper, first we introduce the shooting method(including the method of adjoints and the method of quasilinearization) for two-point boundary value problems of ordinary differential equations with parameters, and give out an example of solving hydrodynamic lubrication equation by using the shooting method. The calculated results are satisfactory.

One-Dimensional Nonuniform Temperature Flow with Heat Transfer by Convection

Yuan Yi-wu

1985, 6(3): 255-263.

Abstract(1948) PDF(509)

Abstract:
In this paper, the author presents a general method for computing velocity and temperature of liquid flow in pipes when the liquid viscosity is an exponential function of temperature and the field of temperature is not uniform in the pipe with heat transfer by convection.

Criteria for the Existence of Solutions to Random Integral and Differential Equations

Ding Xie-ping

1985, 6(3): 265-270.

Abstract(1781) PDF(513)

Abstract:
In [1], we proved a general rondom fixed point theorem and gave some applications. In this paper, we shall give further applications of the theorem. We first obtain a rondom Darbo's fixed point theorem, using the theorem, we give the criteria for the existence of solutions under compactness hypotheses to nonlinear rondom volterra integral equations and the Cauchy problem of nonlinear rondom differential equations. Our theorems improve andgeneralize some main results of Lakshmikanthem^[2], Vaughn^[3,4] as well as De Blasi and Myjak^[5].

Recurrence Formula for B-Splines with Respect a Class of Differential Operators

Xu Yue-sheng

1985, 6(3): 271-275.

Abstract(2003) PDF(437)

Abstract:
In this paper, we give recurrence formula for normalized B-Splines with respect to Standard system {φ^i-1(x)}_i-1^m which is the basic set of solutions to a class of differential operators in view of generalized divided difference——Green function——B-Splines.

A New Method of Integer Linear Programming——Branch Direction Search Method

Xia De-lin

1985, 6(3): 277-284.

Abstract(1643) PDF(446)

Abstract:
An endeavour is made in this paper to present a new and simple ILP algorithm for optimization. It hos the most desirable features of robustness and fast convergence. The algorithm is successful in applying it to some problems arisen in engineering design.

A Discussion on "The Large Deflection Problem of Circular Thin Plate with Variable Thickness Under Uniformly Distributed Loads"

Yeh Kai-yuan, Ye Zhi-ming, Wang Xin-zhi

1985, 6(3): 285-287.

Abstract(1733) PDF(799)

Abstract:

1985 Vol. 6, No. 3