无穷迭代函数系统的遍历定理

度量空间的压缩映射的一个集合称为一个迭代函数系统．凝聚迭代函数系统可以被看成无穷迭代函数系统．研究了紧度量空间上的无穷迭代函数系统．利用Banach极限的特性和均匀压缩性,证明了紧度量空间上无穷迭代函数系统的随机迭代算法满足遍历性．于是,凝聚迭代函数系统的随机迭代算法也满足遍历性．     

超越整函数的某些动力学性质

本文研究了由m个超越整函数{fl,f2,…,fm}生成的随机迭代系统的Fatou集分支的某些动力学性质.运用复动力系统理论与双曲度量理论,得到了随机迭代系统有界Fatou分支不存在的一个判别准则,同时回答了Baker所提出的问题,且给出了随机迭代系统Fatou分支为单连通的一个充分条件,推广了Bergweiler的结果.     

随机迭代系统的有界Fatou分支的存在性

本文研究了由m个超越整函数函数f1,f2,···,fm生成的随机迭代系统的Fatou分支的有界性问题.利用复动力系统理论的方法,得到一个Fatou连通分支U分别作为游荡域和非游荡域有界的条件,推广了Zheng的结果,同时也是对Baker的问题在随机迭代系统情形的一个回答.     

计算微分代数系统稳定域的迭代Lyapunov函数方法

用迭代Lyapunov函数方法对微分代数系统稳定域进行了研究,根据所研究的微分代数系统形式,构造一个Lyapunov函数,然后对这个Lyapunov函数进行逐次迭代,给出了微分代数系统稳定域逐次扩大的迭代算法,数值实验表明迭代Lyapunov函数方法应用于微分代数系统稳定域的估计比单个Lyapunov函数具有良好的优越性。     

Zalcman引理在随机迭代函数族动力系统中的应用

本文根据Schwick的思想,利用Zalcman引理讨论了随机迭代函数族动力系统,指出了函数族随机迭代动力系统的Fatou集和函数族衍生半群动力系统的Fatou集定义差别明显但却等价.并获得了如下正规定则,设■上的非线性解析函数,i∈M},其中M为非空指标集,■,若对任意的指标序列σ=(j_1,j_2,…,j_n,…)∈Σ_M,迭代序列■在点z处正规,则函数族■本身在点z处正规.     

超整函数族Julia集的Hausdorff维数

Stallard曾经用一族特殊的整函数说明了:超越整函数的Julia集的Hausdorff维数可以无限接近1.本文证明了该函数族的随机迭代的Julia集的Hausdorff维数也可无限接近于1.另一方面,对任意自然数M及任意实数d∈(1,2),本文给出了M个元素的整函数族其随机迭代的Julia集的Hausdorff维数等于d.     

一种分形插值函数的最大值问题

通过迭代函数系统构造出一种分形插值函数,从研究迭代过程入手,得到了关于这种自仿射分形插值函数的一些性质和特点.在垂直比例因子1/2d1的情况下,证明最大值的存在性,并计算出此类分形插值函数的最大值.     

向量递归迭代函数系统及其不变测度

本文阐述了RIFS和IFS之间的关系,并对定义在一组紧空间上的向量递归迭代函数系统(VRIFS),定义了Markov算子,给出Markov算子是压缩算子的条件,描述了其不动点即广义递归迭代函数系统的不变测度.文中还给出了相应的拼贴定理.     

非光滑有界凸域上全纯自映射的随机迭代

该文在经典的Wolff-Denjoy理论的基础上研究C~n中有界严格凸域与有界弱凸域上随机迭代的收敛性问题.给出了有界严格凸域中全纯映射的随机迭代存在内闭一致收敛到边界上的常值映射的子序列的限制条件;而在有界弱凸域中,所给的限制条件强了很多,但全纯映射的随机迭代的收敛性却减弱了.该文所给定理的证明方法可以证明单个解析函数的相应结果的迭代理论.     

迭代函数系统的吸引子和OSC集

主要研究迭代函数系统的吸引子,OSC集和它们之间的关系．其中重点分析了吸引子的结构．首先分析Rd上几类迭代函数系统的吸引子结构以及它和OSC集之间的关系,然后在此基础上具体分析并得到了R上一些相关有趣的结果,同时也证明了它们的复杂性．     

基于一类新的胞腔排除遗传算法求解迭代函数系逆问题

提出求解迭代函数系（IFS）逆问题的一类有效遗传算法,该算法基于新发展的可拼接/可分解编码,并结合使用胞腔排除技巧,对于典型图像的应用表明;该方法可有效应用于基于矩匹配表示的IFS逆向题求解,从而为IFS逆问题的数值方法研究提供了一条新颖途径。     

直觉模糊支付合作对策的核仁解

本文主要研究支付值为直觉模糊集的合作对策问题及其模糊核仁解.首先定义了直觉模糊集的得分函数和精确函数,并给出其排序方法,得到基于直觉模糊集的合作对策模型和适合这种模型的相应定义,同时提出了直觉模糊核仁解的概念;其次运用新的排序方法将求核仁解的问题转化为求解双目标非线性规划问题;最后通过实例分析验证了该方法的可行性和有效性。     

Invariant measures for parabolic IFS with overlaps and random continued fractions

We study parabolic iterated function systems (IFS) with overlaps on the real line. An ergodic shift-invariant measure with positive entropy on the symbolic space induces an invariant measure on the limit set of the IFS. The Hausdorff dimension of this measure equals the ratio of entropy over Lyapunov exponent if the IFS has no ``overlaps.' We focus on the overlapping case and consider parameterized families of IFS, satisfying a transversality condition. Our main result is that the invariant measure is absolutely continuous for a.e. parameter such that the entropy is greater than the Lyapunov exponent. If the entropy does not exceed the Lyapunov exponent, then their ratio gives the Hausdorff dimension of the invariant measure for a.e. parameter value, and moreover, the local dimension of the exceptional set of parameters can be estimated. These results are applied to a family of random continued fractions studied by R. Lyons. He proved singularity above a certain threshold; we show that this threshold is sharp and establish absolute continuity for a.e. parameter in some interval below the threshold.

     

Fractal Tilings from Iterated Function Systems

A simple, yet unifying method is provided for the construction of tilings by tiles obtained from the attractor of an iterated function system (IFS). Many examples appearing in the literature in ad hoc ways, as well as new examples, can be constructed by this method. These tilings can be used to extend a fractal transformation defined on the attractor of a contractive IFS to a fractal transformation on the entire space upon which the IFS acts.     

Ruelle operator with nonexpansive IFS on the line

Ruelle operator defined by weakly contractive iterated function systems (IFS) satisfying the open set condition was discussed in the paper [K.S. Lau, Y.L. Ye, Ruelle operator with nonexpansive IFS, Studia Math. 148 (2001) 143-169]. There, one of our theorems gave a sufficient condition for the possession of the Perron-Frobenius property. In this paper we consider Ruelle operator defined by nonexpansive IFS on the line instead of by weakly contractive one. And we prove, under the same condition, that the newly defined Ruelle operator has the Perron-Frobenius property. It extends the Ruelle-Perron-Frobenius theorem partially to the nonexpansive IFS.     

A new exact method for obtaining the multifractal spectrum of multiscaled multinomial measures and IFS invariant measures

In this paper we present a new exact method for obtaining the multifractal spectrum of multiscaled multinomial measures and invariant measures associated with iterated function systems (IFS). A multinomial measure is shown to be generated as the invariant measure of an associated IFS. Then, the multifractal spectrum of the measure is determined by a couple of parametric implicit equations. This analysis generalizes some results previously obtained for the case of single-scaled multinomial measures (e.g., the binomial measure). A geometric interpretation of this new framework working in the space of codes of the IFS gives new insight into the nature of the multifractal formalism. This paper extends the results presented in Gutiérrez et. al. Fractals 4, (1996) 17–27.     

Finite-element modeling of the particle clustering effect in a powder-metallurgy-processed ceramic-particle-reinforced metal matrix composite on its mechanical properties

A new numerical method is proposed to predict the effect of particle clustering on grain boundaries in a ceramic- particle-reinforced metal matrix composite on its mechanical properties, and micromechanical finite-element simulation of stress–strain responses in composites with random and clustered arrangements of ceramic particles are carried out. A particular material modeled and analyzed is a TiC-particle-reinforced Al matrix composite processed by powder metallurgy. A representative volume element of a composite microstructure with 5 vol.% TiC is reconstructed based on the tetrakaidecahedral grain boundary structure by using a modified random sequential adsorption. The model proposed in this study accurately represents the stress concentrations and particle-particle interactions during deformation of the powder-metallurgy-processed composite. A comparison with the random-arrangement model shows that the present numerical approach is more accurate in simulating the behavior of the composite material.     

基于深度学习的直觉模糊集隶属度确定方法

直觉模糊集隶属度、非隶属度和犹豫度的确定方法是直觉模糊集理论与应用研究中一个十分重要的问题,其直接影响着相关方法的可扩展性及应用结果。然而,现有方法存在主观性强、标准难以统一等问题,并且大多基于模拟数据进行实验,难以应用至实际数据。针对上述问题以及大规模非结构化数据,提出一种基于深度学习的直觉模糊集隶属度、非隶属度和犹豫度确定方法。新方法克服了传统方法的技术和思维局限,拓展了直觉模糊集相关问题的研究思路,为其实际应用提供了更多可能。     

Node insertion in Coalescence Fractal Interpolation Function

The Iterated Function System (IFS) used in the construction of Coalescence Hidden-variable Fractal Interpolation Function (CHFIF) depends on the interpolation data. The insertion of a new point in a given set of interpolation data is called the problem of node insertion. In this paper, the effect of insertion of new point on the related IFS and the Coalescence Fractal Interpolation Function is studied. Smoothness and Fractal Dimension of a CHFIF obtained with a node are also discussed.     

Self-similar sets satisfying the common point property

A self-similar set is a fixed point of iterated function system (IFS) whose maps are similarities. We say that a self-similar set satisfies the common point property if the intersection of images of the attractor under the maps of the IFS is a singleton and this point has a common pre-image, under the maps of the IFS, and the pre-image is in the attractor.Self-similar sets satisfying the common point property were introduced in Sirvent (2008) in the context of space-filling curves. In the present article we study some basic topological and dynamical properties of self-similar sets satisfying the common point property. We show examples of this family of sets.We consider attractors of a sub-IFS, an IFS formed from the original IFS by removing some maps. We put conditions on this attractors for having the common point property, when the original IFS have this property.