When a low dimensional chaotic attractor is embedded in a three dimensional space its topological properties are embedding-dependent. We show that there are just three topological properties that depend on the embedding: parity, global torsion, and knot type. We discuss how they can change with the embedding. Finally, we show that the mechanism that is responsible for creating chaotic behavior is an invariant of all embeddings. These results apply only to chaotic attractors of genus one, which covers the majority of cases in which experimental data have been subjected to topological analysis. This means that the conclusions drawn from previous analyses, for example that the mechanism generating chaotic behavior is a Smale horseshoe mechanism, a reverse horseshoe, a gateau roule, an S-template branched manifold, ..., are not artifacts of the embedding chosen for the analysis.
Continuous and discrete time systems possessing strange non-chaotic attractors are under investigation. It is demonstrated that unpredictable trajectories exist in the dynamics. A recent numerical technique, the sequential test, is utilized to show the presence of unpredictability.
We investigate the response of quasiperiodically driven nonlinear systems exhibiting strange non- chaotic attractors (SNAs) to deterministic input signals. We show that if one uses two square waves in aperiodic manner as input to a quasiperiodically driven double-well Duffing oscillator system, the response of the system can produce logical output controlled by such a forcing. Changing the threshold or biasing of the system changes the output to another logic operation and memory latch. The interplay of nonlinearity and quasiperiodic forcing yields logic behaviour and the emergent out- come of…
We consider strange attractors of two dimensional generalized map with one nonlinearity such that Lozi, Hénon and Belykh maps are particular cases of it. We describe technique of invariant expanding and contracting cones creation for study of hyperbolic properties. Theorems of singular hyperbolic attractors for new modifications of Lozi, Hénon and Belykh-type maps are presented.
In this paper, we investigate a mathematical modeling of biochemical processes which makes it possible to determine the adaptation of a biosystem to open environmental conditions.
Bubbling route to strange nonchaotic attractor in a nonlinear series LCR circuit with a nonsinusoidal force
我们确定了一个新的路线诞生的一个奇怪的非混沌吸引子（SNA）的准周期强迫电子电路与非正弦（方波）的力作为准周期力之一，通过数值和实验研究。我们发现，气泡出现在股的准周期吸引子由于不稳定性引起的附加方波型力。然后，气泡扩大，并作为控制参数的函数而变得越来越皱。最后，气泡变得非常褶皱（而环面的其余部分基本上不受影响），导致SNA的诞生，我们称之为\emph{bubbling route to SNA}。我们从实验和数值数据的最大李雅普诺夫指数和他们的方差，庞加莱映射，傅立叶振幅谱和频谱分布函数的特征和确认这一诞生。我们还强烈证实了SNA的诞生通过冒泡路线的有限时间李雅普诺夫指数的分布。
Institut für KI-Sicherheit, Deutsches Zentrum für Luft- und Raumfahrt (DLR)（德国航空航天中心人工智能安全研究所）；Ludwig-Maximilians-Universität (LMU)（慕尼黑大学）；University College Cork（科克大学）；INFANT Research Centre, University College Cork（科克大学INFANT研究中心）；Institut für Frontier Materials auf der Erde und im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR)（德国航空航天中心地外前沿材料研究所）
It is shown that the incorporation of linear sink/source terms in the three-wave resonance interaction model results in the time dependence of the wave amplitudes, which could exhibit the properties of a strange attractor. This finding demonstrates that the transition to turbulent dynamics of the waves could be related not only to the coupling of wave triads but also to the establishing of the strange attractor-like dynamics within individual wave triads.
Interruption of torus doubling bifurcation and genesis of strange nonchaotic attractors in a quasiperiodically forced map : Mechanisms and their characterizations
The effect of noise on a hyperbolic strange attractor in the system of two coupled van der Pol oscillators
我们研究了在庞加莱截面中具有Smale - Williams型双曲混沌吸引子的物理可实现的流动系统的噪声效应[S. P. Kuznetsov，Phys. Rev. Lett. 95，2005，144101]。数值结果表明，只要稍微改变吸引子的初始条件，就可以得到无噪声系统的轨迹对噪声轨道的一致逼近，即所谓的“阴影”轨迹。我们提出了一种算法，用于定位的阴影轨迹在系统中考虑。使用该算法，我们表明，噪声轨道和近似的一个之间的平均距离基本上不依赖于观察的时间间隔的长度，但只对噪声强度。这种依赖性在噪声强度的宽范围内几乎是线性的。研究发现，对于弱噪声，李雅普诺夫指数对噪声强度的依赖性不明显。而在强噪声情况下，系统的最大李雅普诺夫指数减小，甚至变为负值，表明外界噪声对混沌有抑制作用。
Different routes to chaos via strange nonchaotic attractor in a quasiperiodically forced system
研究了一类拟周期受迫动力系统的奇异非混沌吸引子。几条路线，包括标准的奇怪的非混沌吸引子的外观发生，被证明是可实现的在同一模型中的两个参数（$f-ε$）域的系统。特别地，借助于双参数（$f-ε$）相图，证明了环面通过SNA从倍周期到混沌的转变，环面通过SNA从倍周期到混沌的破缺以及分形环面的倍周期分岔。更有趣的是，为了接近奇怪的非混沌吸引子，存在的几个新的分歧对应的环面鼓泡的新现象的环面进行了描述。特别指出了通向混沌的新途径：（1）双频准周期性$\to$环面加倍$\to$环面并合，然后环面逐步分形，（二）双频率准周期性$\to$环面加倍$\to$混沌$\to$ SNA $\to$混沌$\to$逆环面加倍$\to$环面$\to$环面开始后的环面气泡通过SNA打破混沌或随后通过SNA开始环面加倍路径进入混沌。通过计算系统的李雅普诺夫指数、缠绕数、功率谱测度和维数等特征量，证实了奇异非混沌吸引子的存在性.各种分叉背后的机制也进行了简要讨论。
Delay differential equations (DDEs) are infinite-dimensional systems, so even a scalar, unforced nonlinear DDE can exhibit chaos. Lyapunov exponents are indicators of chaos and can be computed by comparing the evolution of infinitesimally close trajectories. We convert DDEs into partial differential equations with nonlinear boundary conditions, then into ordinary differential equations (ODEs) using the Galerkin projection. The solution of the resulting ODEs approximates that of the original DDE system; for smooth solutions, the error decreases exponentially as the number of terms used in the G…
In this paper we analyze local structure of several chaotic attractors recently suggested in literature as pseudohyperbolic. The absence of tangencies and thus the presence of the pseudohyperbolicity is verified using the method of angles that includes computation of distributions of the angles between the corresponding tangent subspaces. Also we analyze how volume expansion in the first subspace and the contraction in the second one occurs locally. For this purpose we introduce a family of instant Lyapunov exponents. Unlike the well known finite time ones, the instant Lyapunov exponents show …
Computing geometric Lorenz attractors with arbitrary precision
Lorenz吸引子是由E. N. Lorenz是\emph{strange attractors}的第一个例子。然而，洛伦兹的研究主要是基于（非严格）数值模拟，直到最近，证明存在的洛伦兹吸引仍然难以捉摸。为了解决这个问题，一些作者引入了几何洛伦兹模型，并证明了几何洛伦兹模型有一个奇怪的吸引子。在2002年，原始的洛伦兹模型表现得像一个几何洛伦兹模型，因此有一个奇怪的吸引子。在本文中，我们表明几何洛伦兹吸引子是可计算的，以及它们的物理措施。
We study the spatial spread of out-of-time-ordered correlators (OTOCs) in coupled map lattices (CMLs) of quasiperiodically forced nonlinear maps. We use instantaneous speed (IS) and finite-time Lyapunov exponents (FTLEs) to investigate the role of strange non-chaotic attractors (SNAs) on the spatial spread of the OTOC. We find that these CMLs exhibit a characteristic on and off type of spread of the OTOC for SNA. Further, we provide a broad spectrum of the various dynamical regimes in a two-parameter phase diagram using IS and FTLEs. We substantiate our results by confirming the presence of SN…
