熵极小动力系统的复杂性

设X是一个紧致度量空间,f:X→X是一个连续映射,(X,f)是熵极小的.该文首先证明了f是强遍历的;另外,如果还假设X中存在f的一个真的(拟)弱几乎周期点,则得到f具有正拓扑熵且对任意的n1,f~n是遍历敏感依赖的.因此,f在Li-Yorke和Takens-Ruelle意义下是混沌的.该文所得结论改进和推广了最近的一些结论.     

环面上的动力系统的遍历性

设 f 为定义在环面上的连续流 ,当 f 无奇点时 ,文中证明了 :f 为唯一遍历的充要条件是 f 最多存在一条周期轨道 ;环面上的任一轨道均为周期轨道的充要条件是 f存在一个非遍历的不变测度μ,使其对任何非空开集 U,均有 μ( U) >0 .     

连续自映射及其扭扩半流的不变测度

本文研究了紧致度量空间上连续自映射及连续半流的不变测度,并且证明了如下结论:(1)在拓扑等价的无不动点的连续半流的不变测度之间以及在连续自映射及其扭扩半流的不变测度之间存在一一对应;(2)作为(1)的应用,给出如下结论(见[2,定理2.1]):“环面上无不动点的连续流是唯一遍历的当且仅当它至多有一条周期轨”一个易接受的证明.     

连续自映射及其扭扩半流的不变测度

本文研究了紧致度量空间上连续自映射及连续半流的不变测度,并且证明了如下结论(1)在拓扑等价的无不动点的连续半流的不变测度之间以及在连续自映射及其扭扩半流的不变测度之间存在一一对应;(2)作为(1)的应用,给出如下结论(见[2,定理2.1])"环面上无不动点的连续流是唯一遍历的当且仅当它至多有一条周期轨"一个易接受的证明.     

关于连续变换的遍历性质的一些注记

设(X,d)是一个紧的距离空间,T是(X,d)上的连续变换.利用平均遍历定理证明了:对任意的x∈X,1/n sum from i=0 to n-1 f(T~i x)在C(X)上收敛.该结果是连续变换的Birkhoff型个别遍历定理的推广.由此结果研究了T的其它遍历性质,特别,不依赖深刻的Choquet积分表示定理,给出了遍历分解定理的一个较为简单而直接的证明.     

Devaney定义下变换的拓扑和随机性质的关系

利用拓扑和遍历理论对Devaney混沌意义下变换的弱混合与拓扑混合、拓扑传递及初值敏感的关系进行了研究,改进了已有文献的结论,证明了弱混合则初值敏感.     

关于连续区间映射的敏感依赖性

首先证明:若区间映射f是敏感依赖的,则f的拓扑熵ent(f)>0.然后通过引入一种扩张映射进一步证明了敏感依赖的区间映射的拓扑熵的下确界为0,即,上式中拓扑熵的下界0是最优的.最后通过实例展示稠混沌、Spatio-temporal混沌、Li-Yorke敏感及敏感性之间是几乎互不蕴含的.     

关于二维定向流形上动力系统的分类问题

本文研究了二维定向流形M~2上只有孤立临界点且可有无穷多分界线与极限分界线的连续流M_t~2的拓扑分类。证明了(1)M_t~2可按某个确定的程序分解成一些广义规范区域的并集,而且如果它们相交,则仅交在它们的边界上;(2)设M_t~((1)),M_t~((2))表示M~2上两个只具有孤立临界点的连续流,M_t~((1))与M_t~((2))是拓扑等价的,当且仅当它们有相同的广义规范区域的分解。     

CNC系统路径遍历的时间最优控制算法

针对计算机数控(CNC)系统给定路径的遍历问题,给出了一种加减速控制算法,使CNC系统的路径遍历时间最小.由于CNC系统的优化变量(加速度)为线性的存在于时间最优指标和约束条件中,且沿坐标方向加速度有界.因此通常这类时间最小路径遍历问题具有Bang-bang的控制结构,即任意时刻至少有一个坐标方向存在最大加/减速度.针对一类参数化路径,推导了沿坐标方向加速度与曲线局部特性间的关系.保证系统在Bang-bang控制情况下,实现路径精确遍历.1/4和1/2圆弧最短时间遍历问题的仿真结果,验证算法的有效性.     

拟生灭过程几种遍历性的判别准则(Ⅱ)

本文是文[7]的继续,研究了连续时间拟生灭过程,给出了一类连续时间拟生灭过程l-遍历和几何遍历行之有效的判别准则,并证明其不可能是多项式一致遍历和强遍历的.     

Several sufficient conditions for sensitive dependence on initial conditions

This paper is concerned with sensitive dependence on initial conditions for maps and semi-flows. Several sufficient conditions for sensitive dependence are given, where it is not required that maps and semi-flows are continuous and spaces are compact. In particular, it is shown that if a measure-preserving map (resp. a measure-preserving semi-flow) on a metric probability space with a fully supported measure is topologically strongly ergodic, then it has sensitive dependence. These results relax and extend the conditions of some existing results.     

大偏差定理与初值敏感性

本文讨论了动力系统的统计性质和动力性质的某些关系.对于紧致度量空间X上的连续自映射f,我们证明了:如果f满足大偏差定理,那么f是初值敏感的当且仅当f不是极小等度连续的.     

RELATIONS BETWEEN SOLUTIONS TO STOCHASTIC DIFFERENTIAL EQUATIONS DRIVEN BY SEMIMARTINGALE WITH NON-LIPSCHITZ COEFFICIENTS

In this paper, a class of stochastic differential equations (SDEs) driven by semi-martingale with non-Lipschitz coefficients is studied. We investigate the dependence of solutions to SDEs on the initial value. To obtain a continuous version, we impose the conditions on the local characteristic of semimartingale. In this case, it gives rise to a flow of homeomorphisms if the local characteristic is compactly supported.     

Structural Stability for the Brinkman Equations of Porous Media

Explicit a priori continuous dependence estimates are derived for the Brinkman equations for non-isothermal flow in porous media. Continuous dependence on the cooling coefficient is shown when a boundary condition of Newton cooling type is employed. Continuous dependence on the model itself is proved when the Boussinesq model is allowed to change to one appropriate to penetrative convection. The final result derives an a priori continuous dependence estimate for the heat supply and body force.     

弱混合的一个等价条件

Let X be a compact metric space containing at least two points and let f ： X → X be continuous. In this paper, we introduce the notion of totally maximum sensitive （TMS, for short） and prove that f is weakly mixing if and only if it is TMS, and if X = [0, 1], then f is weakly mixing if and only if it is 2-maximum sensitive.     

Dynamics of quasicontinuous systems

Quasicontinuous functions are continuous on a residual subset of their domain. The class includes many standard examples from dynamical systems, including the baker transformation and interval exchange maps. We present standard results of continuous topological dynamics (such as that sensitive dependence follows from transitivity and dense periodic points) which extend to quasicontinuous dynamics     

Devaney’s chaos on uniform limit maps

Let (X, d) be a compact metric space and f_n : X → X a sequence of continuous maps such that (f_n) converges uniformly to a map f. The purpose of this paper is to study the Devaney’s chaos on the uniform limit f. On the one hand, we show that f is not necessarily transitive even if all f_n mixing, and the sensitive dependence on initial conditions may not been inherited to f even if the iterates of the sequence have some uniform convergence, which correct two wrong claims in [1]. On the other hand, we give some equivalence conditions for the uniform limit f to be transitive and to have sensitive dependence on initial conditions. Moreover, we present an example to show that a non-transitive sequence may converge uniformly to a transitive map.     

On sensitive sets and regionally proximal sets of group actions

Semigroup Forum - We introduce the concepts of S-sets and Q-sets for a flow (a group action on a compact metric space) and prove that a transitive flow is sensitive if and only if there exists an...     

直线同胚的嵌入流及其应用

设M是一个C~r(r≥0)流形,f:M→M为给定的同胚,f是否可以嵌入一个M上的C~r流?这是一个很有意义也很困难的问题。到目前为止已有不少人做了不少工作,但只对一维的情形才有较完整的结果。Sterberg较早地通过研究直线的局部同胚的共轭类,证明了直线的保向同胚在其双曲不动点附近可局部地嵌入一连续流。P.F.Lam对无不动点的可     

Fixed points of endomorphisms of trace monoids

It is proved that the fixed point submonoid and the periodic point submonoid of a trace monoid endomorphism are always finitely generated. If the dependence alphabet is a transitive forest, it is proved that the set of regular fixed points of the (Scott) continuous extension of an endomorphism to real traces is Ω-rational for every endomorphism if and only if the monoid is a free product of free commutative monoids.