Chen Yushu

STUDY FOR THE BIFURCATION TOPOLOGICAL STRUCTURE AND THE GLOBAL COMPLICATED CHARACTER OF A KIND OF NONLINEAR FINANCE SYSTEM(I)

Based on the mathematical model of a kind of complicated financial system all possible things that the model shows in the operation of our country’s macro-financial system were analyzed, such as balance, stable periodic, fractal, Hopf-bifurcation, the relationship between parameters and Hopf-biburcations, and chaotic motion etc. By the changes of parameters of all economic meanings, the conditions on which the complicated behaviors occur in such a financial system, and the influence of the adjustment of the macro-economic policies and adjustment of some parameter on the whole financial system behavior were analyzed. This study will deepen people’s understanding of the lever function of all kinds of financial policies.

The subharmonic bifurcation solution of nonlinear Mathieu's equation and Euler dynamic buckling problems

A new approach is presented in this paper on the basis of dynamic systems theory. This paper presents the form of a generic classification of stable response diagrams for the nonlinear Mathieu equation. In addition, a general method is presented for determining the topological type of the response diagram for a given equation. This method has been successfully applied to Euler dynamic buckling problems. Some new results are obtained.

Bifurcation in a nonlinear duffing system with multi-frequency external periodic forces

By introducing nonlinear freqyency, using Floquet theory and referring to the characteristics of the solution when it passes through the transition boundaries, all kinds of bifurcation modes and their transition boundaries of Duffing equation with two periodic excitations as well as the possible ways to chaos are studied in this paper.

New bifurcation patterns in elementary bifurcation problems with single-side constraint

Bifurcations with constraints are open problems appeared in research on periodic bifurcations of nonlinear dynamical systems, but the present singularity theory doesn’t contain any analytical methods and results about it. As the complement to singularity theory and the first step to study on constrained bifurcations, here are given the transition sets and persistent perturbed bifurcation diagrams of 10 elementary bifurcation of codimension no more than three.

Global bifurcations and chaos in a Van der Pol-Duffing-Mathieu system with three-well potential oscillator

Semi-analytical and semi-numerical method is used to investigate the global bifurcations and chaos in the nonlinear system of a Van der Pol-Duffing-Mathieu oscillator. Semi-analytical and semi-numerical method means that the autonomous system, called Van der Pol-Duffing system, is analytically studied to draw all global bifurcations diagrams in parameter space. These diagrams are called basic bifurcation diagrams. Then fixing parameter in every space and taking parametrically excited amplitude as a bifurcation parameter, we can observe the evolution from a basic bifurcation diagram to chaotic pattern by numerical methods.

CLASSIFICATION OF BIFURCATIONS FOR NONLINEAR DYNAMICAL PROBLEMS WITH CONSTRAINTS

Bifurcation of periodic solutions widely existed in nonlinear dynamical systems is a kind of constrained one in intrinsic quality because its amplitude is always non-negative. Classification of the bifurcations with the type of constraint was discussed. All its six types of transition sets are derived, in which three types are newly found and a method is proposed for analyzing the constrained bifurcation.

Threshold value for diagnosis of chaotic nature of the data obtained in nonlinear dynamic analysis

In this paper surrogate data method of phase-randomized is proposed to identify the random or chaotic nature of the data obtained in dynamic analysis. The calculating results validate the phase-randomized method to be useful as it can increase the extent of accuracy of the results. And the calculating results show that threshold values of the random timeseries and nonlinear chaotic timeseries have marked difference.

Response of parametrically excited Duffing-van der Pol oscillator with delayed feedback

The dynamical behaviour of a parametrically excited Duffing-van der Pol oscillator under linear-plus-nonlinear state feedback control with a time delay is concerned. By means of the method of averaging together with truncation of Taylor expansions, two slow-flow equations on the amplitude and phase of response were derived for the case of principal parametric resonance. It is shown that the stability condition for the trivial solution is only associated with the linear terms in the original systems besides the amplitude and frequency of parametric excitation. And the trivial solution can be stabilized by appreciate choice of gains and time delay in feedback control. Different from the case of the trivial solution, the stability condition for nontrivial solutions is also associated with nonlinear terms besides linear terms in the original system. It is demonstrated that nontrivial steady state responses may lose their stability by saddle-node (SN) or Hopf bifurcation (HB) as parameters vary. The simulations, obtained by numerically integrating the original system, are in good agreement with the analytical results.

Self-excited vibration of the shell-liquid coupled system induced by dry friction

The nonlinear vibration theory and the experimental modal analysis are used in this paper to study the self-excited vibration of the shell-liquid coupled system induced by dry friction. The effect of dry friction stick-slip coefficients and rubbing velocity on self-excited vibration, and the limit cycle and Hopf bifurcation solution of the system are obtained. In particular, it is shown that the phenomenon of 4 point (or 6 point) water droplet spurting of the Chinese cultural relic Dragon Washbasin is the result of the perfect combination of the self-excited vibration induced by dry friction and its special modes, which indicates the significant scientific value of the Chinese cultural relic Dragon Washbasin.

On monotone iterative method for initial value problems of nonlinear second-order integro-differential equations in Banach spaces

Using the monotone iterative method and Mönch fixed point theorem, the existence of solutions and coupled minimal and maximal quasisolutions of initial value problems for mixed monotone second-order integro-differential equations in Banach spaces are studied. Some existence theorems of solutions and coupled minimal and maximal quasisolutions are obtained.