Bifurcation of limit cycles by perturbing piecewise non-Hamiltonian systems with nonlinear switching manifold

This paper is devoted to the study of limit cycles that can bifurcate of a perturbation of piecewise non-Hamiltonian systems with nonlinear switching manifold. We derive the first order Melnikov function to these systems. As application, the sharp upper bound of the number of bifurcated limit cycles of two concrete systems, whose switching manifolds are algebraic curves, is presented.     

Morrey Regularity of Solutions of Nonlinear Elliptic Systems of Arbitrary Order with Restrictions on the Modulus of Ellipticity

We investigate the dependence of the regularity of generalized solutions of nonlinear elliptic systems on the modulus of ellipticity and regularity of the right-hand side. We establish Morrey regularity with limit exponent determined by the modulus of ellipticity in the case where the right-hand side belongs to a space with a norm stronger than the Dini function. These conditions are exact for second-order systems, namely, for any violation of the Dini condition, we construct a solution that does not belong to the Morrey space with limit exponent.     

Analysis and synthesis of nonlinear systems having limit surfaces with prescribed stability properties

A method is presented for determining the dynamics of a system so that it will have prescribed hypersurfaces as limit sets with preassigned stability properties. This method is applicable not only to the synthesis of systems, but also to the analysis of nonlinear systems. This is equivalent to determining the approximate analytical solutions for multiple limit sets, or the boundary of the domain of attraction. Examples which verify this method are included.     

A cubic differential system with nine limit cycles

Advances in Computer Algebra software have made calculations possible that were previously intractable. Our particular interest is in the investigation of limit cycles of nonlinear differential equations. We describe some recent developments in handling very large computations involving resultants and present an example of a nonlinear differential system of degree three with nine small amplitude limit cycles surrounding a focus. We know of no examples of cubic systems with more than this number bifurcating from a fine focus, as opposed to a centre. Our example appears to be the first to have been obtained without recourse to some numerical calculation.     

Boolean Monomial Dynamical Systems

An important problem in the theory of finite dynamical systems is to link the structure of a system with its dynamics. This paper contains such a link for a family of nonlinear systems over the field with two elements. For systems that can be described by monomials (including Boolean AND systems), one can obtain information about the limit cycle structure from the structure of the monomials. In particular, the paper contains a sufficient condition for a monomial system to have only fixed points as limit cycles. This condition depends on the cycle structure of the dependency graph of the system and can be verified in polynomial time.Received February 2, 2004     

Oscillations in some nonlinear economic relationships

In this paper we consider a simple family of nonlinear dynamical systems generated by smooth functions. Some theorems for the existence and the uniqueness of the limit cycles of the systems are presented. If f and g are generating functions with unique limit cycles and xf(x) < xg(x), for all x ≠ 0, then according to the ‘bounding theorem’ proved in the paper, the limit cycle of the system generated by f is bounded by the limit cycle of the system generated by g. This gives us a method to estimate the amplitude of the oscillations also for systems for which we do not know the generating function exactly. As an application we extend the nonlinear business cycle model proposed by Tönu Puu (1989).     

On a double cycle and resonances

We consider systems with 3/2 degrees of freedom close to nonlinear autonomous Hamiltonian ones in the case where the perturbed autonomous systems have a double limit cycle. Then the initial non-autonomous systems have a special resonance zone. The structure of this zone is investigated.     

An existence theorem for some semilinear elliptic systems

An existence theorem is obtained for a class of semilinear, second order, uniformly elliptic systems obtained formally from a variational principle and modeled on nonlinear Helmholtz systems. Superlinear growth of the nonlinear term precludes application of standard methods to these systems. Indeed, we permit very rapid growth of the nonlinear term, so the underlying functional is not defined on the Hilbert space within which a solution is naturally sought. Mollification of the nonlinear term nonetheless results in the resulting functional satisfying the Palais-Smale condition; critical points are determined by solution of a dynamical system. The limit of vanishing mollification then produces a weak solution of the original problem.     

包围多个奇点的极限环的不存在性与唯二性

本文给出一类非线性方程没有及至多有两个包围三个奇点的极限环的若干条件，作为应用讨论了几类多项式系统的极限环分支。     

Exact number of limit cycles for a family of rigid systems

For a given family of planar differential equations it is a very difficult problem to determine an upper bound for the number of its limit cycles. Even when this upper bound is one it is not always an easy problem to distinguish between the case of zero and one limit cycle. This note mainly deals with this second problem for a family of systems with a homogeneous nonlinear part. While the condition that allows us to separate the existence and the nonexistence of limit cycles can be described, it is very intricate.

     

Visualization of four limit cycles of two-dimensional quadratic systems in the parameter space

This paper deals with the visualization of a domain that contains four limit cycles for quadratic dynamical systems of first-order differential equations with real coefficients. The visualization of the domain is carried out in the three-dimensional space of coefficients corresponding to the nonlinear part of the quadratic system. Theoretical and practical aspects of the numerical solution of the Cauchy problem for unstable systems are discussed.     

多自由度非线性振动系统的内共振

本文研究多自由度非线性自治系统的周期解问题,我们推广了KBM[1]法,本方法可以求得极限环的相图,振幅,周期及其稳定性.     

TARGET PATTERNS AND SPIRAL WAVES IN REACTION-DIFFUSION SYSTEMS WITH LIMIT CYCLE KINETICSAND WEAK DIFFUSION

1.IntroductionTargetpatternsandspiralwavesarecommonlyobservedincertainmodelsofchemicalandbiologicalsystemssuchastheBelousov-ZhabotinskiireactionandthesocialamoebasDictyosteliumdiscoideium(of.11--4]andthereferencestherein).Thesesystemsaregovernedbyachemicalorbiologicalreactionandspatialdiffusion,i.e.reaction-diffusionequations.Generallyspeaking,atargetpatternisasetofconcentricringsofconstantconcentrationeachmovingoutward.Alonganyradialline,thepatternbehavesasymptoticallylikeaperiodictravellin…     

对一类非线性扰动方程的分析

本文研究了一类非线性扰动方程，确定自治扰动方程双曲不动点的稳定和不稳定流形的相对位置，给出了存在唯一极限环的参数范围，并应用于电机工程和力学中一类非线性系统。     

几类非线性微分系统极限环的存在性和唯一性

给出系统(E1),(E2)和(E3)等非线性微分系统存在闭轨的一些新的判定条件,推广了非线性微分系统极限环的存在性和唯一性许多这方面研究的结果,并大大改进了它们的某些条件．在这个基础上,还给出了系统(E1)和(E2)恰有一个极限环的一组充分条件．     

Nonlinear martingale problems involving singular integrals

We study a class of nonlinear martingale problems in one dimension, that involve a singular integral of the density in the drift term, and are related to systems of particles with singular interactions. First, we prove existence and uniqueness of regular solutions of the associated nonlinear evolution equation. Then, we establish a suitable framework and conditions where the martingale problem is well posed. This extends the results of Bonami et al. (J. Funct. Anal. 165 (1999) 390) to a wide class of coefficients and initial conditions. Finally, we obtain our solution of the martingale problem as the chaotic limit of some systems of particles interacting through regular approximating kernels.     

Semilinear parabolic problems in thin domains with a highly oscillatory boundary

In this paper, we study the behavior of the solutions of nonlinear parabolic problems posed in a domain that degenerates into a line segment (thin domain) which has an oscillating boundary. We combine methods from linear homogenization theory for reticulated structures and from the theory on nonlinear dynamics of dissipative systems to obtain the limit problem for the elliptic and parabolic problems and analyze the convergence properties of the solutions and attractors of the evolutionary equations.     

The existence of the exponentially stable limit cycle for a class of nonlinear systems

In this paper, the exponentially stable limit cycle phenomenon for a class of nonlinear systems is investigated. Based on the analytic method, the existence and uniqueness of the exponentially stable limit cycle for such systems can be guaranteed. Moreover, the amplitude of oscillation, the period of oscillation, and guaranteed convergence rate can be correctly estimated. Finally, two numerical examples are provided to illustrate the use of the main result.     

Zero relaxation and dissipation limits for hyperbolic conservation laws

We are interested in hyperbolic systems of conservation laws with relaxation and dissipation, particularly the zero relaxation limit. Such a limit is of interest in several physical situations, including gas flow near thermo-equilibrium, kinetic theory with small mean free path, and viscoelasticity with vanishing memory. In this article we study hyperbolic systems of two conservation laws with relaxation. For the stable case where the equilibrium speed is subcharacteristic with respect to the frozen speeds, we illustrate for a model in viscoelasticity that no oscillation develops for the nonlinear system in the zero relaxation limit. For the marginally stable case where the equilibrium speed may equal one of the frozen speeds, we show for a model in phase transitions that no oscillation arises when the dissipation is present and goes to zero more slowly than the relaxation. Our analysis includes the construction of suitable entropy pairs to derive energy estimates. We need such energy estimates not only for the compactness properties but also for the deviation from the equilibrium of the solutions for the relaxation systems. The theory of compensated compactness is then applied to study the oscillation in the zero relaxation limit. © 1993 John Wiley & Sons, Inc.     

Effective approaches to explore rich dynamics of delay-differential equations

Discrete models are proposed to delve into the rich dynamics of nonlinear delayed systems under Euler discretization, such as backwards bifurcations, stable limit cycles, multiple limit-cycle bifurcations and chaotic behavior. The effect of breaking the special symmetry of the system is to create a wide complex operating conditions which would not otherwise be seen. These include multiple steady states, complex periodic oscillations, chaos by period doubling bifurcations. Effective computation of multiple bifurcations, stable limit cycles, symmetrical breaking bifurcations and chaotic behavior in nonlinear delayed equations is developed.