摘要
针对光滑多翅膀混沌系统不易于构造的问题,基于光滑代数函数提出两个新光滑多分段非线性函数,并用新光滑多分段非线性函数构造了新光滑单方向多翅膀S-M混沌系统和新光滑二方向网格多翅膀S-M混沌系统.然后,分析了两个新光滑多翅膀混沌系统的非线性动力学行为,主要包括相图、平衡点、不变性、耗散性、李亚普诺夫指数、分维数和庞加莱截面,并得到了多翅膀混沌吸引子的产生机理.其产生机理为指标2鞍焦平衡点用于产生翅膀.此外,通过单方向多翅膀S-M混沌吸引子和二方向网格多翅膀S-M混沌吸引子的电路实现,验证了理论推导和数值仿真的正确性.
2020-04-19 收到第1稿,2020-06-30 收到修改稿.
1963年,Lorenz提出了Lorenz混沌系统,其混沌吸引子的拓扑结构与蝴蝶的形状十分相似,是一种双翅膀混沌系统,该系统的提出掀起了混沌研究的热
2008年,Yu
2016年,Zhou
自1980年,Shimizu和Moriok
本文首先以双翅膀S-M混沌系统为基础,基于代数函数提出了两个新多分段非线性函数和.然后,通过采用非线性函数代替双翅膀S-M混沌系统中的平方项,构造出新单方向多翅膀S-M混沌系统.通过采用多分段非线性函数代替新单方向多翅膀S-M混沌系统中的状态变量z,构造出新二方向网格多翅膀S-M混沌系统.随后,分析了新单方向多翅膀S-M混沌系统和新二方向网格多翅膀S-M混沌系统的非线性动力学行为,并得到了新单方向多翅膀S-M混沌吸引子和新二方向网格多翅膀S-M混沌吸引子的产生机理.其产生机理为指标2鞍焦平衡点用于产生翅膀.同时,对上述系统进行了电路实现.
首先引入代数函数,如
(1) |
随着参数值的变化,g(x)∈[-1,1].当时,代数函数变为具体的代数函

图1 代数函数的曲线
Fig.1 Algebraic function
(2) |
其中,,,,(),为正整数.由
(3) |
其中,a=0.75,b=0.45是参数. x,y和z是状态变量.
为了构造单方向多翅膀S-M混沌系统,用多分段非线性函数代替双翅膀S-M混沌系统(3)中的项,可得单方向多翅膀S-M混沌系统(4).
(4) |
单方向多翅膀S-M混沌系统(4)可以产生4翅膀S-M混沌吸引子,6翅膀S-M混沌吸引子和8翅膀S-M混沌吸引子.当初值为,仿真时间为1000 s,4翅膀S-M混沌吸引子在x-z平面的相图如

图2 4翅膀S-M混沌吸引子在x-z平面的相图
Fig.2 Phase diagrams of the 4-wing S-M chaotic attractor in the x-z plane

图3 4翅膀S-M混沌吸引子的电路实现
Fig.3 Circuit implementation of the 4-wing S-M chaotic attractor
为了研究单方向多翅膀S-M混沌吸引子的产生机理,对平衡点进行分析.令此混沌系统(4)中的,可得
(5) |
由
(6) |
根据

图4 当时,多分段非线性函数
Fig.4 Multisegment nonlinear function with
6翅膀S-M混沌吸引子的平衡点Q±n(x±n,y±n,z±n)和特征值,如
单方向多翅膀S-M混沌系统(4)在的变换下保持不变,即单方向多翅膀S-M混沌系统(4)关于z轴对称.通过体积的散度来计算单方向多翅膀S-M混沌系统(4)的耗散性,即
(7) |
因此,单方向多翅膀S-M混沌系统(4)是耗散的.
本节以6翅膀S-M混沌吸引子为例来研究李亚普诺夫指数、分维数和庞加莱截面.当初值为,仿真时间为3000 s,6翅膀S-M混沌吸引子的李亚普诺夫指数如

图5 6翅膀S-M混沌吸引子的李亚普诺夫指数
Fig.5 Lyapunov exponents of the 6-wing S-M chaotic attractor
由

图6 6翅膀S-M混沌吸引子的庞加莱截面
Fig.6 Poincaré section of the 6-wing S-M chaotic attractor
本节利用代数函数构造多分段非线性函数,并利用多分段非线性函数构造二方向网格多翅膀S-M混沌系统.此系统能产生二方向网格多翅膀S-M混沌吸引子.利用代数函数构造多分段非线性函数,其可以表示为
(8) |
其中,,,(),为整数.由
(9) |
其中,,是系统参数.和分别由

(a) 网格多翅膀S-M混沌吸引子(,)
(a) -grid multi-wing S-M chaotic attractor (,)

(b) 网格多翅膀S-M混沌吸引子(N=2,M=0)
(b) -grid multi-wing S-M chaotic attractor(N=2,M=0)

(c) 网格多翅膀S-M混沌吸引子(N=3,M=0)
(c) -grid multi-wing S-M chaotic attractor(N=3,M=0)

(d) 网格多翅膀S-M混沌吸引子(,)
(d) -grid multi-wing S-M chaotic attractor(,)

(e) 网格多翅膀S-M混沌吸引子(,)
(e) -grid multi-wing S-M chaotic attractor(,)

(f) 网格多翅膀S-M混沌吸引子(,)
(f) -grid multi-wing S-M chaotic attractor(,)
图7 网格多翅膀S-M混沌吸引子在x-z平面的相图
Fig.7 Phase diagrams of the -grid multi-wing S-M chaotic attractors in the x-z plane
网格多翅膀S-M混沌吸引子的Multisim电路实现结果如

图8 网格多翅膀S-M混沌吸引子的电路实现
Fig.8 Circuit implementation of the -grid multi-wing S-M chaotic attractor
本节通过分析平衡点来研究二方向网格多翅膀S-M混沌系统的产生机理.令二方向网格多翅膀S-M混沌系统(9)中,可得
(10) |
由
(11) |
由

图9 当时,多分段非线性函数
Fig.9 Multisegment nonlinear function with
网格多翅膀S-M混沌吸引子的平衡点和特征值,如
二方向网格多翅膀S-M混沌系统(9)的不变性和耗散性计算方法与单方向多翅膀S-M混沌系统(4)相同,这里不再详细讨论.
本节以网格多翅膀S-M混沌吸引子为例来分析李亚普诺夫指数、分维数和庞加莱截面.当初值为,仿真时间为3000 s,网格多翅膀S-M混沌系统的李亚普诺夫指数如

图10 网格多翅膀S-M混沌吸引子的李亚普诺夫指数
Fig.10 Lyapunov exponents of the 6×4 -grid multi-wing S-M chaotic attractor
由

图11 网格多翅膀S-M混沌吸引子的庞加莱截面
Fig.11 Poincaré section of the -grid multi-wing S-M chaotic attractor
以6翅膀S-M混沌系统(,)为例,分析李亚普诺夫指数如

图12 随参数变化的李亚普诺夫指数
Fig.12 Lyapunov exponents with varying parameter

图13 分岔图
Fig.13 Bifurcation diagram
对经典双翅膀S-M混沌系统(3)、单方向多翅膀S-M混沌系统(4)以及二方向网格多翅膀S-M混沌系统(9),分别从SE复杂
本文基于光滑代数函数构造了两个新光滑多分段非线性函数和.然后,采用这两个新光滑多分段非线性函数构造了新光滑单方向多翅膀S-M混沌系统和新光滑二方向网格多翅膀S-M混沌系统.翅膀的个数由指标2鞍焦平衡点的个数来确定.需要说明的是,该光滑代数函数也可以被用于构造其他新光滑多分段非线性函数.此外,本文构造的新光滑单方向多翅膀S-M混沌系统和新光滑二方向网格多翅膀S-M混沌系统可应用于保密通信,图像加密等领域.
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