Herrero R, Farjas J, Pi F, Orriols G
Departament de Física, Universitat Politècnica de Catalunya, 08222 Terrassa, Spain.
Departament de Física, Campus Montilivi, Universitat de Girona, 17003 Girona, Spain.
Chaos. 2022 Feb;32(2):023116. doi: 10.1063/5.0069878.
We have found a way for penetrating the space of the dynamical systems toward systems of arbitrary dimension exhibiting the nonlinear mixing of a large number of oscillation modes through which extraordinarily complex time evolutions may arise. The system design is based on assuring the occurrence of a number of Hopf bifurcations in a set of fixed points of a relatively generic system of ordinary differential equations, in which the main peculiarity is that the nonlinearities appear through functions of a linear combination of the system variables. The paper outlines the design procedure and presents a selection of numerical simulations with a variety of designed systems whose dynamical behaviors are really rich and full of unknown features. For concreteness, the presentation is focused on illustrating the oscillatory mixing effects on the periodic orbits, through which the harmonic oscillation born in a Hopf bifurcation becomes successively enriched with the intermittent incorporation of other oscillation modes of higher frequencies while the orbit remains periodic and without the necessity of bifurcating instabilities. Even in the absence of a proper mathematical theory covering the nonlinear mixing mechanisms, we find enough evidence to expect that the oscillatory scenario be truly scalable concerning the phase-space dimension, the multiplicity of involved fixed points, and the range of time scales so that extremely complex but ordered dynamical behaviors could be sustained through it.
我们已经找到了一种方法,能够穿透动力系统的空间,进入任意维度的系统,这些系统展现出大量振荡模式的非线性混合,由此可能产生极其复杂的时间演化。系统设计基于确保在一个相对一般的常微分方程组的一组不动点中出现多个霍普夫分岔,其主要特点是,非线性通过系统变量的线性组合的函数出现。本文概述了设计过程,并给出了对各种设计系统的数值模拟结果,这些系统的动力学行为确实丰富且充满未知特性。具体而言,本文重点阐述了对周期轨道的振荡混合效应,通过这种效应,霍普夫分岔中产生的谐波振荡会随着其他高频振荡模式的间歇性并入而不断丰富,同时轨道保持周期性,且无需分岔失稳。即使在缺乏涵盖非线性混合机制的恰当数学理论的情况下,我们也找到了足够的证据,预期这种振荡情形在相空间维度、相关不动点的多重性以及时间尺度范围方面具有真正的可扩展性,从而能够通过它维持极其复杂但有序的动力学行为。