一类摄动系统的Poincaré分叉与极限环

本文利用临界情形的隐函数存在定理讨论了一类摄动系统分支周期解的存在性与稳定性,利用后继函数法讨论了该系统极限环的存在性、唯一性和稳定性。     

Ⅲ类二次系统极限环的惟一性(Ⅰ)

证明了一般的Ⅲ类二次系统当参数a很小时极限环的大范围惟一性,对于一般的参数值a,在适当的条件下也证明了极限环的大范围惟一性.文中也给出了极限环随参数d变化时产生和消失的过程.     

一类余维3的鞍-焦点异宿环分支

对余维3系统X_μ(x)具有包含一个双曲鞍-焦点O_1和一个非双曲鞍-焦点O_2的异宿环f进行了研究.证明了在f的邻域内有可数无穷条周期轨线和异宿轨线,当非粗糙异宿轨线Γ~0破裂时X_μ(x)会产生同宿轨分支,并给出了相应的分支曲线和两种同宿环共存的参数值.在3参数扰动下Γ~0破裂和O_2点产生Hopf分支的情况下,在f的邻域内有一条含O_1点同宿环,可数无效多条的轨线同宿于O_2点分支出的闭轨H_0,一条或无穷多条(可数或连续统的)异宿轨线等.     

PERSISTENCE AND STABILITY IN ARATIO‐DEPENDENT PREDATOR‐PREY SYSTEM WITH DELAY AND HARVESTING

ABSTRACT. . This paper aims to study the effect of time‐delay and combined harvesting on a Michaelis‐Menten type ratio‐dependent predator‐prey system. Dynamical behaviors such as persistence, stability, bifurcation, et cetera, are studied critically. Computer simulations are carried out to illustrate our analytical findings.     

Periodic solutions of Abel differential equations

For a class of polynomial non-autonomous differential equations of degree n, we use phase plane analysis to show that each equation in this class has n periodic solutions. The result implies that certain rigid two-dimensional systems have at most one limit cycle which appears through multiple Hopf bifurcation.     

Dynamical understanding of loop soliton solution for several nonlinear wave equations

It has been found that some nonlinear wave equations have one-loop soliton solutions. What is the dynamical behavior of the so-called one-loop soliton solution? To answer this question, the travelling wave solutions for four nonlinear wave equations are discussed. Exact explicit parametric representations of some special travelling wave solutions are given. The results of this paper show that a loop solution consists of three different breaking travelling wave solutions. It is not one real loop soliton travelling wave solution.     

迭代微分方程解的存在性及分支

本文讨论迭代微分方程ｘ（ｔ）＝ｆ（ｘ（ｔ），ｘ（ｘ（ｔ）））的解的性态，并在ｆ（ｘ（ｔ），ｘ（ｘ（ｔ）））＝（ｘ＾２（ｔ）－μ）ｘ（ｘ（ｔ））时研究解的分支问题，更正了现有文献中的错误，结出了正确，完整的结果。     

包含极值点和分枝点的解曲线跟踪算法的摄动解法

本文提出了采用摄动格式求解非线性方程组的解曲线跟踪算法的计算格式.文中着重讨论了解曲线上非正则点的搜索,以及从这些非正则点——转向点或分枝点——继续跟踪超临界平衡路径的计算方法.文中把这一算法应用于弹性薄壳的屈曲分析。通过柱壳和环壳的算例得到它们的整个屈曲过程的平衡路径和变形形态.     

Spatio-temporal symmetries and bifurcations via bi-orthogonal decompositions

Summary A tool for analyzing spatio-temporal complex physical phenomena was recently proposed by the authors, Aubry et al. [5]. This tool consists in decomposing a spatially and temporally evolving signal into orthogonal temporal modes (temporal “structures”) and orthogonal spatial modes (spatial “structures”) which are coupled. This allows the introduction of a temporal configuration space and a spatial one which are related to each other by an isomorphism. In this paper, we show how such a tool can be used to analyze space-time bifurcations, that is, qualitative changes in both space and time as a parameter varies. The Hopf bifurcation and various spatio-temporal symmetry related bifurcations, such as bifurcations to traveling waves, are studied in detail. In particular, it is shown that symmetry-breaking bifurcations can be detected by analyzing the temporal and spatial eigenspaces of the decomposition which then lose their degeneracy, namely their invariance under the symmetry. Furthermore, we show how an extension of the theory to “quasi-symmetries” permits the treatment of nondegenerate signals and leads to an exponentially decreasing law of the energy spectrum. Examples extracted from numerically obtained solutions of the Kuramoto-Sivashinsky equation, a coupled map lattice, and fully developed turbulence are given to illustrate the theory.