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Nonlinear Dynamics and Entropy of Complex Systems with Hidden and Self-excited Attractors

A special issue of Entropy (ISSN 1099-4300). This special issue belongs to the section "Complexity".

Deadline for manuscript submissions: closed (31 January 2019) | Viewed by 86326

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Laboratory of Nonlinear Systems, Circuits & Coplexity (LaNSCom), Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
Interests: electrical and electronics engineering; mathematical modeling; control theory; engineering, applied and computational mathematics; numerical analysis; mathematical analysis; numerical modeling; modeling and simulation; robotics
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Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
Interests: chaos; nonlinear dynamics; optimization
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Department of Electrical Engineering, University of Dschang, Dschang P.O. Box 134, Cameroon
Interests: chaos theory; nonlinear phenomena; nonlinear circuits; hidden attractors; synchronization
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Faculty of Electronics Sciences, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, Puebla 72570, Mexico
Interests: chaos theory; chaotic dynamics and applications; nonlinear circuits and systems; mathematical modeling; electronics; fractional-order chaotic systems; fractional-order calculus
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Center for Nonlinear Systems, Chennai Institute of Technology, Tamil Nadu 600069, India
Interests: optimal control theory; artificial intelligence; adaptive control; neural networks
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Special Issue Information

Dear Colleagues,

In the last few years, entropy has been a basic and important concept in information theory. It is also often used as a measure of the degree of chaos in systems, e.g., Lyapunov exponents, fractal dimension, and entropy are usually used to describe the complexity of chaotic systems. Thus, it would be very interesting to study entropy in nonlinear systems. Additionally, there has been an increasing interest in a new classification of nonlinear dynamical systems including two kinds of attractors: Self-excited attractors and hidden attractors. Self-excited attractors can be localized straight forwardly by applying a standard computational procedure. Some interesting examples of systems with self-excited attractors are chaotic systems with different kinds of symmetry, with multi-scroll attractors, with multiple attractors, and with extreme multistability.

In systems with hidden attractors we have to develop a specific computational procedure to identify the hidden attractors due to the fact that the equilibrium points do not help in their localization. Some examples of this kind of systems are chaotic dynamical systems with no equilibrium points, with only stable equilibria, with curves of equilibria, with surfaces of equilibria, and with non-hyperbolic equilibria. There is evidence that hidden attractors play an important role in the various fields ranging from phase-locked loops, oscillators, describing convective fluid motion, model of drilling system, information theory, cryptography to multilevel DC/DC converter. Furthermore, hidden attractors may lead to unexpected and disastrous responses.

The Special Issue is dedicated to the presentation and discussion of the advanced topics of entropy in complex systems with hidden attractors and self-excited attractors. The contribution to the Special Issue should be focus on the aspects of nonlinear dynamics, entropy, and applications of nonlinear systems with hidden and self-excited attractors.

Dr. Christos Volos
Dr. Sajad Jafari
Dr. Jacques Kengne
Dr. Jesus M. Munoz-Pacheco
Dr. Karthikeyan Rajagopal
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nonlinear systems
  • Complex systems
  • Chaos
  • Control
  • Entropy
  • Fractionalorder systems
  • Hidden attractors
  • Self-excited attractors
  • Synchronization

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Published Papers (19 papers)

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Editorial

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4 pages, 169 KiB  
Editorial
Nonlinear Dynamics and Entropy of Complex Systems with Hidden and Self-Excited Attractors
by Christos K. Volos, Sajad Jafari, Jacques Kengne, Jesus M. Munoz-Pacheco and Karthikeyan Rajagopal
Entropy 2019, 21(4), 370; https://doi.org/10.3390/e21040370 - 5 Apr 2019
Cited by 11 | Viewed by 3354
Abstract
In the last few years, entropy has been a fundamental and essential concept in information theory [...] Full article

Research

Jump to: Editorial

12 pages, 1659 KiB  
Article
Bogdanov Map for Modelling a Phase-Conjugated Ring Resonator
by Vicente Aboites, David Liceaga, Rider Jaimes-Reátegui and Juan Hugo García-López
Entropy 2019, 21(4), 384; https://doi.org/10.3390/e21040384 - 10 Apr 2019
Cited by 1 | Viewed by 3050
Abstract
In this paper, we propose using paraxial matrix optics to describe a ring-phase conjugated resonator that includes an intracavity chaos-generating element; this allows the system to behave in phase space as a Bogdanov Map. Explicit expressions for the intracavity chaos-generating matrix elements were [...] Read more.
In this paper, we propose using paraxial matrix optics to describe a ring-phase conjugated resonator that includes an intracavity chaos-generating element; this allows the system to behave in phase space as a Bogdanov Map. Explicit expressions for the intracavity chaos-generating matrix elements were obtained. Furthermore, computer calculations for several parameter configurations were made; rich dynamic behavior among periodic orbits high periodicity and chaos were observed through bifurcation diagrams. These results confirm the direct dependence between the parameters present in the intracavity chaos-generating element. Full article
Show Figures

Figure 1

Figure 1
<p>Phase-conjugated ring resonator with an intracavity chaos-generating element.</p>
Full article ">Figure 2
<p>Phase space (<math display="inline"><semantics> <msub> <mi>y</mi> <mi>n</mi> </msub> </semantics></math>, <math display="inline"><semantics> <msub> <mi>θ</mi> <mi>n</mi> </msub> </semantics></math>), equivalent to a round trip inside the resonator for (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>0.95</mn> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>0.99</mn> </mrow> </semantics></math> and (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>0.998</mn> </mrow> </semantics></math>; in all cases <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0.295</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>ε</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>μ</mi> <mo>=</mo> <mo>−</mo> <mn>0.1</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 3
<p>(<b>a</b>) Bifurcation diagram of local max of <math display="inline"><semantics> <msub> <mi>b</mi> <mi>n</mi> </msub> </semantics></math> as a function of parameter <span class="html-italic">d</span>. (<b>b</b>) Temporal inter peak interval (IPI) of <math display="inline"><semantics> <msub> <mi>b</mi> <mi>n</mi> </msub> </semantics></math> as a function of parameter <span class="html-italic">d</span>; in both plots, the following fixed values were used: <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0.295</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>ε</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>μ</mi> <mo>=</mo> <mo>−</mo> <mn>0.1</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 4
<p>Bifurcation diagram of local max of <math display="inline"><semantics> <msub> <mi>b</mi> <mi>n</mi> </msub> </semantics></math> as a function of parameter <span class="html-italic">k</span>, for <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>0.9837</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>ε</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>μ</mi> <mo>=</mo> <mo>−</mo> <mn>0.1</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 5
<p>Phase space (<math display="inline"><semantics> <msub> <mi>y</mi> <mi>n</mi> </msub> </semantics></math>, <math display="inline"><semantics> <msub> <mi>θ</mi> <mi>n</mi> </msub> </semantics></math>). High periodicity for (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0.2925</mn> </mrow> </semantics></math>, low periodicity for (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0.30434</mn> </mrow> </semantics></math> and chaos for (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>30735</mn> </mrow> </semantics></math>, in all cases <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>9837</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>ε</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>μ</mi> <mo>=</mo> <mo>−</mo> <mn>0.1</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 6
<p>The bifurcation diagram of local max <math display="inline"><semantics> <msub> <mi>b</mi> <mi>n</mi> </msub> </semantics></math> as a function of <math display="inline"><semantics> <mi>ε</mi> </semantics></math> for three different values of <span class="html-italic">k</span> with <span class="html-italic">d</span> fixed in the chaotic region, and <math display="inline"><semantics> <mrow> <mi>μ</mi> <mo>=</mo> <mo>−</mo> <mn>0.1</mn> </mrow> </semantics></math>. (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0.2925</mn> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0.30434</mn> </mrow> </semantics></math> and (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0.30735</mn> </mrow> </semantics></math>.</p>
Full article ">
21 pages, 14391 KiB  
Article
Dynamics and Entropy Analysis for a New 4-D Hyperchaotic System with Coexisting Hidden Attractors
by Licai Liu, Chuanhong Du, Xiefu Zhang, Jian Li and Shuaishuai Shi
Entropy 2019, 21(3), 287; https://doi.org/10.3390/e21030287 - 15 Mar 2019
Cited by 27 | Viewed by 3956
Abstract
This paper presents a new no-equilibrium 4-D hyperchaotic multistable system with coexisting hidden attractors. One prominent feature is that by varying the system parameter or initial value, the system can generate several nonlinear complex attractors: periodic, quasiperiodic, multiple topology chaotic, and hyperchaotic. The [...] Read more.
This paper presents a new no-equilibrium 4-D hyperchaotic multistable system with coexisting hidden attractors. One prominent feature is that by varying the system parameter or initial value, the system can generate several nonlinear complex attractors: periodic, quasiperiodic, multiple topology chaotic, and hyperchaotic. The dynamics and complexity of the proposed system were investigated through Lyapunov exponents (LEs), a bifurcation diagram, a Poincaré map, and spectral entropy (SE). The simulation and calculation results show that the proposed multistable system has very rich and complex hidden dynamic characteristics. Additionally, the circuit of the chaotic system is designed to verify the physical realizability of the system. This study provides new insights into uncovering the dynamic characteristics of the coexisting hidden attractors system and provides a new choice for nonlinear control or chaotic secure communication technology. Full article
Show Figures

Figure 1

Figure 1
<p>Three-dimensional chaotic attractor of system (2) with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial conditions <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mn>4</mn> <mo>,</mo> <mn>4</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math> on the (<b>a</b>) <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>,</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> space, (<b>b</b>) <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>,</mo> <mi>w</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> space, (<b>c</b>) <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>z</mi> <mo>,</mo> <mi>w</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> space, and (<b>d</b>) <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mi>y</mi> <mo>,</mo> <mi>z</mi> <mo>,</mo> <mi>w</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> space.</p>
Full article ">Figure 1 Cont.
<p>Three-dimensional chaotic attractor of system (2) with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial conditions <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mn>4</mn> <mo>,</mo> <mn>4</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math> on the (<b>a</b>) <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>,</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> space, (<b>b</b>) <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>,</mo> <mi>w</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> space, (<b>c</b>) <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>z</mi> <mo>,</mo> <mi>w</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> space, and (<b>d</b>) <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mi>y</mi> <mo>,</mo> <mi>z</mi> <mo>,</mo> <mi>w</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> space.</p>
Full article ">Figure 2
<p>Two-dimensional chaotic attractor of system (2) with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial conditions <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mn>4</mn> <mo>,</mo> <mn>4</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics></math> plane; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics></math> plane; (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics></math> plane; (<b>d</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> plane; (<b>e</b>) <math display="inline"><semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> plane; and (<b>f</b>) <math display="inline"><semantics> <mrow> <mi>z</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> plane.</p>
Full article ">Figure 3
<p>Time series of system (2) with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial conditions <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mn>4</mn> <mo>,</mo> <mn>4</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) <math display="inline"><semantics> <mi>x</mi> </semantics></math> variable; (<b>b</b>) <math display="inline"><semantics> <mi>y</mi> </semantics></math> variable; (<b>c</b>) <math display="inline"><semantics> <mi>z</mi> </semantics></math> variable; and (<b>d</b>) <math display="inline"><semantics> <mi>w</mi> </semantics></math> variable.</p>
Full article ">Figure 4
<p>Frequency spectrum of system (2) with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial conditions <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mn>4</mn> <mo>,</mo> <mn>4</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) the <math display="inline"><semantics> <mi>x</mi> </semantics></math> variable; (<b>b</b>) <math display="inline"><semantics> <mi>y</mi> </semantics></math> variable; (<b>c</b>) <math display="inline"><semantics> <mi>z</mi> </semantics></math> variable; and (<b>d</b>) <math display="inline"><semantics> <mi>w</mi> </semantics></math> variable.</p>
Full article ">Figure 5
<p>LEs of system (2) in dependence on parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mn>4</mn> <mo>,</mo> <mn>4</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 6
<p>Poincaré map of system (2) in dependence on parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mn>4</mn> <mo>,</mo> <mn>4</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math> in the (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics></math> plane and (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>ω</mi> </mrow> </semantics></math> plane.</p>
Full article ">Figure 7
<p>Bifurcation diagram and LEs of system (2) about <math display="inline"><semantics> <mi>a</mi> </semantics></math>, with <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mn>5</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) bifurcation diagram; (<b>b</b>) LE graphs.</p>
Full article ">Figure 8
<p>Bifurcation diagram and LEs of system (2) about <math display="inline"><semantics> <mi>a</mi> </semantics></math>, with <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0.7</mn> <mo>,</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) bifurcation diagram; (<b>b</b>) LE graphs.</p>
Full article ">Figure 9
<p>Bifurcation diagram and LEs of system (2) about <math display="inline"><semantics> <mi>a</mi> </semantics></math>, with <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>4</mn> <mo>,</mo> <mn>5</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) bifurcation diagram; (<b>b</b>) LE graphs.</p>
Full article ">Figure 10
<p>Projections of hidden attractors with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.88922</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math> and initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>z</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> space; (<b>b</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics></math> plane.</p>
Full article ">Figure 11
<p>Projections of hidden attractors with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1.0621</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math> and initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>z</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> space; (<b>b</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics></math> plane.</p>
Full article ">Figure 12
<p>Projections of hidden attractors with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1.2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math> and initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>z</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> space; (<b>b</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics></math> plane.</p>
Full article ">Figure 13
<p>Projections of hidden attractors with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>2.982</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math> and initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>z</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> space; (<b>b</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics></math> plane.</p>
Full article ">Figure 14
<p>Projections of hidden attractors with parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>4.9</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math> and initial value <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>z</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> space; (<b>b</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics></math> plane.</p>
Full article ">Figure 15
<p>Projections of hidden attractors with different initial conditions. Blue attractors‘ initial is <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>2</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, red attractors‘ initial is<math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mo>−</mo> <mn>2</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, and the parameters are <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>: (<b>a</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> plane; (<b>b</b>) attractor in the <math display="inline"><semantics> <mrow> <mi mathvariant="normal">y</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> plane.</p>
Full article ">Figure 16
<p>Bifurcation diagram and LEs of system (2) with <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, initial value <math display="inline"><semantics> <mrow> <mi>Y</mi> <mn>0</mn> <mo>=</mo> <mo stretchy="false">(</mo> <mi>u</mi> <mo>,</mo> <mi>u</mi> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>u</mi> <mo>∈</mo> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mn>5</mn> <mo stretchy="false">]</mo> </mrow> </semantics></math>: (<b>a</b>) bifurcation diagram; (<b>b</b>) LE graphs.</p>
Full article ">Figure 17
<p>Bifurcation diagram and LEs of system (2) with <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, initial value <math display="inline"><semantics> <mrow> <mi>Y</mi> <mn>1</mn> <mo>=</mo> <mo stretchy="false">(</mo> <mi>u</mi> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>u</mi> <mo>∈</mo> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mn>5</mn> <mo stretchy="false">]</mo> </mrow> </semantics></math>: (<b>a</b>) bifurcation diagram; (<b>b</b>) LE graphs.</p>
Full article ">Figure 18
<p>Projections of hidden attractors with different initial conditions. Green attractors‘ initial is <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mn>0.01</mn> <mo>,</mo> <mn>0.01</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, blue attractors‘ initial is <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mn>2.093</mn> <mo>,</mo> <mn>2.093</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, red attractors‘ initial is<math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mn>1.5</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, and parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>: (<b>a</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics></math> plane; (<b>b</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi mathvariant="normal">z</mi> </mrow> </semantics></math> plane; (<b>c</b>) attractor <math display="inline"><semantics> <mrow> <mi mathvariant="normal">y</mi> <mo>−</mo> <mi mathvariant="normal">z</mi> </mrow> </semantics></math> plane; (<b>d</b>) in the <math display="inline"><semantics> <mrow> <mi mathvariant="normal">x</mi> <mo>−</mo> <mi mathvariant="normal">y</mi> <mo>−</mo> <mi mathvariant="normal">z</mi> </mrow> </semantics></math> space; (<b>e</b>) attractor in the <math display="inline"><semantics> <mrow> <mi mathvariant="normal">x</mi> <mo>−</mo> <mi mathvariant="normal">y</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> space; and (<b>f</b>) attractor in the <math display="inline"><semantics> <mrow> <mi mathvariant="normal">x</mi> <mo>−</mo> <mi mathvariant="normal">z</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> space.</p>
Full article ">Figure 18 Cont.
<p>Projections of hidden attractors with different initial conditions. Green attractors‘ initial is <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mn>0.01</mn> <mo>,</mo> <mn>0.01</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, blue attractors‘ initial is <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mn>2.093</mn> <mo>,</mo> <mn>2.093</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, red attractors‘ initial is<math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mn>1.5</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, and parameters <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>: (<b>a</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics></math> plane; (<b>b</b>) attractor in the <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi mathvariant="normal">z</mi> </mrow> </semantics></math> plane; (<b>c</b>) attractor <math display="inline"><semantics> <mrow> <mi mathvariant="normal">y</mi> <mo>−</mo> <mi mathvariant="normal">z</mi> </mrow> </semantics></math> plane; (<b>d</b>) in the <math display="inline"><semantics> <mrow> <mi mathvariant="normal">x</mi> <mo>−</mo> <mi mathvariant="normal">y</mi> <mo>−</mo> <mi mathvariant="normal">z</mi> </mrow> </semantics></math> space; (<b>e</b>) attractor in the <math display="inline"><semantics> <mrow> <mi mathvariant="normal">x</mi> <mo>−</mo> <mi mathvariant="normal">y</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> space; and (<b>f</b>) attractor in the <math display="inline"><semantics> <mrow> <mi mathvariant="normal">x</mi> <mo>−</mo> <mi mathvariant="normal">z</mi> <mo>−</mo> <mi>w</mi> </mrow> </semantics></math> space.</p>
Full article ">Figure 19
<p>SE vs. parameters of the system, initial is <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>,</mo> <mi>z</mi> <mo>,</mo> <mi>ω</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mn>5</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mn>5</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 20
<p>SE vs. initials of the system, where<math display="inline"><semantics> <mrow> <mi>I</mi> <mi>N</mi> <mn>0</mn> <mo>=</mo> <mo stretchy="false">(</mo> <mi>u</mi> <mo>,</mo> <mi>u</mi> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math> (Blue), <math display="inline"><semantics> <mrow> <mi>I</mi> <mi>N</mi> <mn>1</mn> <mo>=</mo> <mo stretchy="false">(</mo> <mi>u</mi> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math> (Red), and <math display="inline"><semantics> <mrow> <mi>I</mi> <mi>N</mi> <mn>2</mn> <mo>=</mo> <mo stretchy="false">(</mo> <mn>0.01</mn> <mi>u</mi> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mo>−</mo> <mn>2</mn> <mi>u</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> (Green); <math display="inline"><semantics> <mrow> <mi>u</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mn>5</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 21
<p>Chaotic characteristics of SE vs. the parameters of the system, with <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mn>5</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mn>5</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>, and the initial <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>w</mi> <mn>0</mn> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>2</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 22
<p>Circuit exhibiting hidden attractors without equilibrium.</p>
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<p>Hidden chaotic attractors of circuit (14) : (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>10</mn> <mi>k</mi> <mi>Ω</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>u</mi> <mi>x</mi> </msub> <mo>−</mo> <msub> <mi>u</mi> <mi>y</mi> </msub> </mrow> </semantics></math> plane; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>10</mn> <mi>k</mi> <mi>Ω</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>u</mi> <mi>y</mi> </msub> <mo>−</mo> <msub> <mi>u</mi> <mi>w</mi> </msub> </mrow> </semantics></math> plane; (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>10</mn> <mi>k</mi> <mi>Ω</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>u</mi> <mi>z</mi> </msub> <mo>−</mo> <msub> <mi>u</mi> <mi>w</mi> </msub> </mrow> </semantics></math> plane; (<b>d</b>) <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>4.9</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>2.041</mn> <mi>k</mi> <mi>Ω</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>u</mi> <mi>x</mi> </msub> <mo>−</mo> <msub> <mi>u</mi> <mi>z</mi> </msub> </mrow> </semantics></math> plane; (<b>e</b>) <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1.0621</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>9.415</mn> <mi>k</mi> <mi>Ω</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>u</mi> <mi>x</mi> </msub> <mo>−</mo> <msub> <mi>u</mi> <mi>z</mi> </msub> </mrow> </semantics></math> plane; (<b>f</b>) <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.88922</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>11.246</mn> <mi>k</mi> <mi>Ω</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>u</mi> <mi>x</mi> </msub> <mo>−</mo> <msub> <mi>u</mi> <mi>z</mi> </msub> </mrow> </semantics></math> plane; (<b>g</b>) <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>2.982</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>3.353</mn> <mi>k</mi> <mi>Ω</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>u</mi> <mi>x</mi> </msub> <mo>−</mo> <msub> <mi>u</mi> <mi>z</mi> </msub> </mrow> </semantics></math> plane; (h) <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1.2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>8.333</mn> <mi>k</mi> <mi>Ω</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>u</mi> <mi>x</mi> </msub> <mo>−</mo> <msub> <mi>u</mi> <mi>z</mi> </msub> </mrow> </semantics></math> plane.</p>
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10 pages, 2979 KiB  
Article
Chaotic Map with No Fixed Points: Entropy, Implementation and Control
by Van Van Huynh, Adel Ouannas, Xiong Wang, Viet-Thanh Pham, Xuan Quynh Nguyen and Fawaz E. Alsaadi
Entropy 2019, 21(3), 279; https://doi.org/10.3390/e21030279 - 14 Mar 2019
Cited by 24 | Viewed by 4376
Abstract
A map without equilibrium has been proposed and studied in this paper. The proposed map has no fixed point and exhibits chaos. We have investigated its dynamics and shown its chaotic behavior using tools such as return map, bifurcation diagram and Lyapunov exponents’ [...] Read more.
A map without equilibrium has been proposed and studied in this paper. The proposed map has no fixed point and exhibits chaos. We have investigated its dynamics and shown its chaotic behavior using tools such as return map, bifurcation diagram and Lyapunov exponents’ diagram. Entropy of this new map has been calculated. Using an open micro-controller platform, the map is implemented, and experimental observation is presented. In addition, two control schemes have been proposed to stabilize and synchronize the chaotic map. Full article
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<p>Strange attractor of the map for <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>0.1</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>x</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>,</mo> <mi>y</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>)</mo> <mo>=</mo> <mo>(</mo> <mn>1.5</mn> <mo>,</mo> <mn>0.5</mn> <mo>)</mo> </mrow> </semantics></math>.</p>
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<p>Bifurcation diagram (<b>a</b>); and Lyapunov exponents (<b>b</b>) when varying <span class="html-italic">c</span> for <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0.1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>0.1</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>x</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>,</mo> <mi>y</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>)</mo> <mo>=</mo> <mo>(</mo> <mn>1.5</mn> <mo>,</mo> <mn>0.5</mn> <mo>)</mo> </mrow> </semantics></math>.</p>
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<p>Arduino Uno board for implementing chaotic the map in Equation (<a href="#FD1-entropy-21-00279" class="html-disp-formula">1</a>).</p>
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<p>Captured waveforms at pins 9 and 10 of the Arduino Uno board.</p>
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<p>Stabilization when applying the proposed control law: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>(</mo> <mi>n</mi> <mo>)</mo> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>y</mi> <mo>(</mo> <mi>n</mi> <mo>)</mo> </mrow> </semantics></math>, and (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics></math> plane.</p>
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<p>Evolution of states when applying the control: (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mi>x</mi> <mi>m</mi> </msub> <mrow> <mo>(</mo> <mi>n</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>x</mi> <mi>s</mi> </msub> <mrow> <mo>(</mo> <mi>n</mi> <mo>)</mo> </mrow> </mrow> </semantics></math> and (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mi>y</mi> <mi>m</mi> </msub> <mrow> <mo>(</mo> <mi>n</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>y</mi> <mi>s</mi> </msub> <mrow> <mo>(</mo> <mi>n</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>.</p>
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<p>Synchronization errors.</p>
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12 pages, 2107 KiB  
Article
Adaptive Synchronization of Fractional-Order Complex Chaotic system with Unknown Complex Parameters
by Ruoxun Zhang, Yongli Liu and Shiping Yang
Entropy 2019, 21(2), 207; https://doi.org/10.3390/e21020207 - 21 Feb 2019
Cited by 16 | Viewed by 3500
Abstract
This paper investigates the problem of synchronization of fractional-order complex-variable chaotic systems (FOCCS) with unknown complex parameters. Based on the complex-variable inequality and stability theory for fractional-order complex-valued system, a new scheme is presented for adaptive synchronization of FOCCS with unknown complex parameters. [...] Read more.
This paper investigates the problem of synchronization of fractional-order complex-variable chaotic systems (FOCCS) with unknown complex parameters. Based on the complex-variable inequality and stability theory for fractional-order complex-valued system, a new scheme is presented for adaptive synchronization of FOCCS with unknown complex parameters. The proposed scheme not only provides a new method to analyze fractional-order complex-valued system but also significantly reduces the complexity of computation and analysis. Theoretical proof and simulation results substantiate the effectiveness of the presented synchronization scheme. Full article
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<p>Dynamic behaviors of the fractional-order complex Lorenz-like System with commensurate order <math display="inline"><semantics> <mi>α</mi> </semantics></math> (<math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>10</mn> <mo>+</mo> <mi>i</mi> <mo>,</mo> <mo> </mo> <mi>b</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mo> </mo> <mi>c</mi> <mo>=</mo> <mn>16</mn> <mo>+</mo> <mn>0.3</mn> <mi>i</mi> </mrow> </semantics></math>). (<b>a</b>) maximal Lyapunov exponent; (<b>b</b>) bifurcation diagram.</p>
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<p>Chaotic attractors of fractional-order complex Lorenz-like system with <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>10</mn> <mo>+</mo> <mi>i</mi> <mo>,</mo> <mo> </mo> <mi>b</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mo> </mo> <mi>c</mi> <mo>=</mo> <mn>16</mn> <mo>+</mo> <mn>0.3</mn> <mi>i</mi> </mrow> </semantics></math> and commensurate order <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.95</mn> </mrow> </semantics></math>.</p>
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<p>Dynamic behaviors of the fractional-order complex Lorenz-like System with commensurate order 0.95 (<math display="inline"><semantics> <mrow> <msup> <mi>a</mi> <mi>r</mi> </msup> <mo>=</mo> <mn>10</mn> <mo>,</mo> <mo> </mo> <mi>b</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mo> </mo> <mi>c</mi> <mo>=</mo> <mn>16</mn> <mo>+</mo> <mn>0.3</mn> <mi>i</mi> </mrow> </semantics></math>). (<b>a</b>) maximal Lyapunov exponent; (<b>b</b>) bifurcation diagram.</p>
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<p>The state trajectories of fractional-order complex Lorenz-like system with <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>10</mn> <mo>+</mo> <mi>i</mi> <mo>,</mo> <mo> </mo> <mi>b</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mo> </mo> <mi>c</mi> <mo>=</mo> <mn>16</mn> <mo>+</mo> <mn>0.3</mn> <mi>i</mi> </mrow> </semantics></math> and commensurate order <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.95</mn> </mrow> </semantics></math>.</p>
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<p>Synchronization errors <span class="html-italic">e</span><sub>1</sub>, <span class="html-italic">e</span><sub>2</sub>, <span class="html-italic">e</span><sub>3</sub> of fractional-order complex Lorenz-like chaotic system.</p>
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<p>Estimated complex parameters of fractional-order complex Lorenz-like chaotic system.</p>
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15 pages, 3574 KiB  
Article
Entropy Analysis and Neural Network-Based Adaptive Control of a Non-Equilibrium Four-Dimensional Chaotic System with Hidden Attractors
by Hadi Jahanshahi, Maryam Shahriari-Kahkeshi, Raúl Alcaraz, Xiong Wang, Vijay P. Singh and Viet-Thanh Pham
Entropy 2019, 21(2), 156; https://doi.org/10.3390/e21020156 - 7 Feb 2019
Cited by 84 | Viewed by 4675
Abstract
Today, four-dimensional chaotic systems are attracting considerable attention because of their special characteristics. This paper presents a non-equilibrium four-dimensional chaotic system with hidden attractors and investigates its dynamical behavior using a bifurcation diagram, as well as three well-known entropy measures, such as approximate [...] Read more.
Today, four-dimensional chaotic systems are attracting considerable attention because of their special characteristics. This paper presents a non-equilibrium four-dimensional chaotic system with hidden attractors and investigates its dynamical behavior using a bifurcation diagram, as well as three well-known entropy measures, such as approximate entropy, sample entropy, and Fuzzy entropy. In order to stabilize the proposed chaotic system, an adaptive radial-basis function neural network (RBF-NN)–based control method is proposed to represent the model of the uncertain nonlinear dynamics of the system. The Lyapunov direct method-based stability analysis of the proposed approach guarantees that all of the closed-loop signals are semi-globally uniformly ultimately bounded. Also, adaptive learning laws are proposed to tune the weight coefficients of the RBF-NN. The proposed adaptive control approach requires neither the prior information about the uncertain dynamics nor the parameters value of the considered system. Results of simulation validate the performance of the proposed control method. Full article
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<p>A bifurcation diagram exhibiting a periodic-doubling route to chaos of the peak of <math display="inline"><semantics> <mi>x</mi> </semantics></math> (<math display="inline"><semantics> <mi>x</mi> </semantics></math> max) of system (1) versus parameter <math display="inline"><semantics> <mi>g</mi> </semantics></math>.</p>
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<p>The three-dimensional (3D) chaotic portrait for system (1) in (<b>a</b>) <span class="html-italic">x</span>-<span class="html-italic">y</span>-<span class="html-italic">z</span> space, (<b>b</b>) <span class="html-italic">x</span>-<span class="html-italic">y</span>-<span class="html-italic">w</span> space, (<b>c</b>) <span class="html-italic">x</span>-<span class="html-italic">z</span>-<span class="html-italic">w</span> space, and (<b>d</b>) <span class="html-italic">y</span>-<span class="html-italic">z</span>-<span class="html-italic">w</span> space.</p>
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<p>The largest Lyapunov exponent of the system (1).</p>
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<p>Values of ApEn, SampEn, and FuzzEn computed from <math display="inline"><semantics> <mrow> <mi>x</mi> <mrow> <mo>(</mo> <mi>n</mi> <mo>)</mo> </mrow> </mrow> </semantics></math> of the system (1) with respect to parameter g.</p>
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<p>Architecture of the neural network.</p>
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<p>The state variables when the proposed control input is activated at <math display="inline"><semantics> <mrow> <mi>t</mi> <mo>=</mo> <mn>50</mn> </mrow> </semantics></math> s.</p>
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<p>The state variables in the presence of the proposed control method.</p>
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<p>Norm of the weights of the RBF-NN.</p>
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<p>Phase portraits of the controlled system.</p>
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<p>The 3-D behavior of the controlled system.</p>
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18 pages, 4267 KiB  
Article
Dynamics and Complexity of a New 4D Chaotic Laser System
by Hayder Natiq, Mohamad Rushdan Md Said, Nadia M. G. Al-Saidi and Adem Kilicman
Entropy 2019, 21(1), 34; https://doi.org/10.3390/e21010034 - 7 Jan 2019
Cited by 51 | Viewed by 4702
Abstract
Derived from Lorenz-Haken equations, this paper presents a new 4D chaotic laser system with three equilibria and only two quadratic nonlinearities. Dynamics analysis, including stability of symmetric equilibria and the existence of coexisting multiple Hopf bifurcations on these equilibria, are investigated, and the [...] Read more.
Derived from Lorenz-Haken equations, this paper presents a new 4D chaotic laser system with three equilibria and only two quadratic nonlinearities. Dynamics analysis, including stability of symmetric equilibria and the existence of coexisting multiple Hopf bifurcations on these equilibria, are investigated, and the complex coexisting behaviors of two and three attractors of stable point and chaotic are numerically revealed. Moreover, a conducted research on the complexity of the laser system reveals that the complexity of the system time series can locate and determine the parameters and initial values that show coexisting attractors. To investigate how much a chaotic system with multistability behavior is suitable for cryptographic applications, we generate a pseudo-random number generator (PRNG) based on the complexity results of the laser system. The randomness test results show that the generated PRNG from the multistability regions fail to pass most of the statistical tests. Full article
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<p>Dynamics of the system (<a href="#FD2-entropy-21-00034" class="html-disp-formula">2</a>) versus the parameter <span class="html-italic">b</span> for the initial values <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math> and with <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>=</mo> <mn>27</mn> </mrow> </semantics></math>: (<b>a</b>) bifurcation diagram; (<b>b</b>) Lyapunov exponents.</p>
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<p>Different orientations on a two-scroll chaotic attractor of the system (<a href="#FD2-entropy-21-00034" class="html-disp-formula">2</a>) for the initial values <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math> and with the parameters <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>=</mo> <mn>27</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>. (<b>a</b>) <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>3</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>)</mo> </mrow> </semantics></math> space; (<b>b</b>) <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mn>4</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>)</mo> </mrow> </semantics></math> space; (<b>c</b>) <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mn>4</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>3</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>)</mo> </mrow> </semantics></math> space; (<b>d</b>) <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mn>4</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>3</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>)</mo> </mrow> </semantics></math> space.</p>
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<p>Hopf bifurcation of the system (<a href="#FD2-entropy-21-00034" class="html-disp-formula">2</a>): (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>=</mo> <mn>5</mn> <mo>.</mo> <mn>5</mn> <mo>&lt;</mo> <msub> <mi>r</mi> <mn>0</mn> </msub> </mrow> </semantics></math>, the orbit of the system is attracted to the stable symmetric equilibria <math display="inline"><semantics> <msub> <mi>E</mi> <mn>2</mn> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>E</mi> <mn>3</mn> </msub> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>=</mo> <mn>6</mn> <mo>.</mo> <mn>5</mn> <mo>&gt;</mo> <msub> <mi>r</mi> <mn>0</mn> </msub> </mrow> </semantics></math>, the orbit of the system is attracted to a stable limit cycle emerging from the symmetric equilibria <math display="inline"><semantics> <msub> <mi>E</mi> <mn>2</mn> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>E</mi> <mn>3</mn> </msub> </semantics></math>.</p>
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<p>Bifurcation diagrams versus parameter <span class="html-italic">r</span> for illustrating the two and three coexisting attractors of the system (<a href="#FD2-entropy-21-00034" class="html-disp-formula">2</a>): (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>1</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>7</mn> </mrow> </semantics></math> for the initial values <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>)</mo> </mrow> </semantics></math> (red) and <math display="inline"><semantics> <mrow> <mo>(</mo> <mo>-</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>)</mo> </mrow> </semantics></math> (blue); (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math> for the initial values <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math> (blue), <math display="inline"><semantics> <mrow> <mo>(</mo> <mo>-</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mo>-</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math> (red) and <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mo>-</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math> (green).</p>
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<p>Multiple coexisting chaotic attractors of the system (<a href="#FD2-entropy-21-00034" class="html-disp-formula">2</a>) when <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>1</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>7</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>=</mo> <mn>9</mn> <mo>.</mo> <mn>41</mn> </mrow> </semantics></math> for the initial values <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>)</mo> </mrow> </semantics></math> (red) and <math display="inline"><semantics> <mrow> <mo>(</mo> <mo>-</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>)</mo> </mrow> </semantics></math> (blue). (<b>a</b>) <math display="inline"><semantics> <msub> <mi>x</mi> <mn>1</mn> </msub> </semantics></math>–<math display="inline"><semantics> <msub> <mi>x</mi> <mn>2</mn> </msub> </semantics></math> plane; (<b>b</b>) <math display="inline"><semantics> <msub> <mi>x</mi> <mn>2</mn> </msub> </semantics></math>–<math display="inline"><semantics> <msub> <mi>x</mi> <mn>3</mn> </msub> </semantics></math> plane; (<b>c</b>) <math display="inline"><semantics> <msub> <mi>x</mi> <mn>1</mn> </msub> </semantics></math>–<math display="inline"><semantics> <msub> <mi>x</mi> <mn>4</mn> </msub> </semantics></math> plane; (<b>d</b>) <math display="inline"><semantics> <msub> <mi>x</mi> <mn>2</mn> </msub> </semantics></math>–<math display="inline"><semantics> <msub> <mi>x</mi> <mn>4</mn> </msub> </semantics></math> plane.</p>
Full article ">Figure 6
<p>Three coexisting attractors with <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>=</mo> <mn>27</mn> </mrow> </semantics></math>: (<b>a</b>,<b>c</b>,<b>e</b>) different perspectives on the coexistence of the chaotic and two stable fixed-point attractors for the initial values <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math> (blue), <math display="inline"><semantics> <mrow> <mo>(</mo> <mo>-</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mo>-</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math> (red) and <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mo>-</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math> (green); (<b>b</b>,<b>d</b>,<b>f</b>) the corresponding time series of the state variables <math display="inline"><semantics> <msub> <mi>x</mi> <mn>1</mn> </msub> </semantics></math>, <math display="inline"><semantics> <msub> <mi>x</mi> <mn>2</mn> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>x</mi> <mn>4</mn> </msub> </semantics></math>, respectively.</p>
Full article ">Figure 7
<p>SamEn in the parameter <span class="html-italic">r</span>-initial value plane for <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>-</mo> <msub> <mi>x</mi> <mn>10</mn> </msub> </mrow> </semantics></math> plane; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>-</mo> <msub> <mi>x</mi> <mn>20</mn> </msub> </mrow> </semantics></math> plane; (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>-</mo> <msub> <mi>x</mi> <mn>30</mn> </msub> </mrow> </semantics></math> plane; (<b>d</b>) <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>-</mo> <msub> <mi>x</mi> <mn>40</mn> </msub> </mrow> </semantics></math> plane.</p>
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<p>SamEn versus varying two of the initial values for <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>=</mo> <mn>27</mn> </mrow> </semantics></math>: (<b>a</b>) <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mn>10</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>20</mn> </msub> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>2</mn> <mo>,</mo> <msub> <mi>x</mi> <mn>20</mn> </msub> <mo>,</mo> <msub> <mi>x</mi> <mn>30</mn> </msub> <mo>,</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mn>10</mn> </msub> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <msub> <mi>x</mi> <mn>40</mn> </msub> <mo>)</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 9
<p>The statistical tests NIST SP800-22 of the pseudorandom number generator (PRNG) that generated by <math display="inline"><semantics> <msub> <mi>x</mi> <mn>1</mn> </msub> </semantics></math>, <math display="inline"><semantics> <msub> <mi>x</mi> <mn>2</mn> </msub> </semantics></math>, <math display="inline"><semantics> <msub> <mi>x</mi> <mn>3</mn> </msub> </semantics></math>, <math display="inline"><semantics> <msub> <mi>x</mi> <mn>4</mn> </msub> </semantics></math> of the system (<a href="#FD2-entropy-21-00034" class="html-disp-formula">2</a>) with <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>∈</mo> <mo>[</mo> <mn>27</mn> <mo>,</mo> <mn>29</mn> <mo>]</mo> </mrow> </semantics></math> and for the initial values <math display="inline"><semantics> <mrow> <mo>(</mo> <mn>2</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mo>-</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math>. (<b>a</b>) Block-Frequency, Discrete Fourier Transform, Frequency (Monobit), Random Excursions, Random Excursions Variant, Serial-1, Serial-2, Linear Complexity, and Longest Run of Ones, respectively; (<b>b</b>) Approximate Entropy, Cumulative Sums (Forward), Cumulative Sums (Reverse), Lempel-ziv Compression, Non-overlapping Template, Overlapping Template, Binary Matrix Rank, Runs, and Universal Statistical.</p>
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16 pages, 2843 KiB  
Article
The Complexity and Entropy Analysis for Service Game Model Based on Different Expectations and Optimal Pricing
by Yimin Huang, Xingli Chen, Qiuxiang Li and Xiaogang Ma
Entropy 2018, 20(11), 858; https://doi.org/10.3390/e20110858 - 8 Nov 2018
Cited by 9 | Viewed by 4451
Abstract
The internet has provided a new means for manufacturers to reach consumers. On the background of the widespread multichannel sales in China, based on a literature review of the service game and multichannel supply chain, this paper builds a multichannel dynamic service game [...] Read more.
The internet has provided a new means for manufacturers to reach consumers. On the background of the widespread multichannel sales in China, based on a literature review of the service game and multichannel supply chain, this paper builds a multichannel dynamic service game model where the retailer operates an offline channel and the manufacturer operates an online channel and offers customers the option to buy online and pick up from the retailer’s store (BOPS). The manufacturer and the retailer take maximizing the channel profits as their business objectives and make channel service game under optimal pricing. We carry on theoretical analysis of the model and perform numerical simulations from the perspective of entropy theory, game theory, and chaotic dynamics. The results show that the stability of the system will weaken with the increase in service elasticity coefficient and that it is unaffected by the feedback parameter adjustment of the retailer. The BOPS channel strengthens the cooperation between the manufacturer and the retailer and moderates the conflict between the online and the offline channels. The system will go into chaotic state and cause the system’s entropy to increase when the manufacturer adjusts his/her service decision quickly. In a chaotic state, the system is sensitive to initial conditions and service input is difficult to predict; the manufacturer and retailer need more additional information to make the system clear or use the method of feedback control to delay or eliminate the occurrence of chaos. Full article
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<p>Multichannel service supply chain.</p>
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<p>The stable regions of system (9) with <math display="inline"> <semantics> <mrow> <msub> <mi>γ</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>0.25</mn> </mrow> </semantics> </math> and <math display="inline"> <semantics> <mrow> <msub> <mi>γ</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>0.55</mn> </mrow> </semantics> </math>.</p>
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<p>The evolution process of system (9) with change of <math display="inline"> <semantics> <mi>ξ</mi> </semantics> </math> when <math display="inline"> <semantics> <mrow> <msub> <mi>γ</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>0.55</mn> </mrow> </semantics> </math>. (<b>a</b>) The bifurcation diagram and (<b>b</b>) the entropy diagram.</p>
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<p>The evolution process of system (9) with change of <math display="inline"> <semantics> <mi>ξ</mi> </semantics> </math> with <math display="inline"> <semantics> <mrow> <msub> <mi>γ</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>0.7</mn> </mrow> </semantics> </math>. (<b>a</b>) The bifurcation diagram and (<b>b</b>) the entropy diagram.</p>
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<p>The bifurcation diagrams of the system (9) with change of <math display="inline"> <semantics> <mi>β</mi> </semantics> </math>. (<b>a</b>) <math display="inline"> <semantics> <mrow> <mi>ξ</mi> <mo>=</mo> <mn>0.3</mn> </mrow> </semantics> </math> and (<b>b</b>) <math display="inline"> <semantics> <mrow> <mi>ξ</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics> </math>.</p>
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<p>Chaotic attractor of system (9), (<b>a</b>) <math display="inline"> <semantics> <mrow> <mi>β</mi> <mo>=</mo> <mn>0.3</mn> </mrow> </semantics> </math>, <math display="inline"> <semantics> <mrow> <mi>ξ</mi> <mo>=</mo> <mn>0.48</mn> </mrow> </semantics> </math>; (<b>b</b>) <math display="inline"> <semantics> <mrow> <mo> </mo> <mi>β</mi> <mo>=</mo> <mn>0.3</mn> </mrow> </semantics> </math>, <math display="inline"> <semantics> <mrow> <mi>ξ</mi> <mo>=</mo> <mn>0.58</mn> </mrow> </semantics> </math>; and (<b>c</b>) <math display="inline"> <semantics> <mrow> <mo> </mo> <mi>β</mi> <mo>=</mo> <mn>0.3</mn> </mrow> </semantics> </math>, <math display="inline"> <semantics> <mrow> <mi>ξ</mi> <mo>=</mo> <mn>0.74</mn> <mo>.</mo> </mrow> </semantics> </math></p>
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<p>Initial value sensitivity of service level in stable system.</p>
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<p>Initial value sensitivity of service level in a chaotic system.</p>
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<p>Profit diagram of system (9).</p>
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<p>Average profit diagram of system (9).</p>
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<p>The evolution process of controlled system with <math display="inline"> <semantics> <mi>P</mi> </semantics> </math> changing. (<b>a</b>) The bifurcation diagram and (<b>b</b>) the entropy diagram.</p>
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13 pages, 408 KiB  
Article
The Co-existence of Different Synchronization Types in Fractional-order Discrete-time Chaotic Systems with Non–identical Dimensions and Orders
by Samir Bendoukha, Adel Ouannas, Xiong Wang, Amina-Aicha Khennaoui, Viet-Thanh Pham, Giuseppe Grassi and Van Van Huynh
Entropy 2018, 20(9), 710; https://doi.org/10.3390/e20090710 - 14 Sep 2018
Cited by 23 | Viewed by 3837
Abstract
This paper is concerned with the co-existence of different synchronization types for fractional-order discrete-time chaotic systems with different dimensions. In particular, we show that through appropriate nonlinear control, projective synchronization (PS), full state hybrid projective synchronization (FSHPS), and generalized synchronization (GS) can be [...] Read more.
This paper is concerned with the co-existence of different synchronization types for fractional-order discrete-time chaotic systems with different dimensions. In particular, we show that through appropriate nonlinear control, projective synchronization (PS), full state hybrid projective synchronization (FSHPS), and generalized synchronization (GS) can be achieved simultaneously. A second nonlinear control scheme is developed whereby inverse full state hybrid projective synchronization (IFSHPS) and inverse generalized synchronization (IGS) are shown to co-exist. Numerical examples are presented to confirm the findings. Full article
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Figure 1
<p>Phase space plot for the fractional Hénon map with <math display="inline"><semantics> <mrow> <mfenced separators="" open="(" close=")"> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>,</mo> <mspace width="4.pt"/> <msub> <mi>b</mi> <mn>1</mn> </msub> </mfenced> <mo>=</mo> <mfenced separators="" open="(" close=")"> <mn>1.4</mn> <mo>,</mo> <mspace width="4.pt"/> <mn>0.3</mn> </mfenced> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>υ</mi> <mo>=</mo> <mn>0.984</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mfenced separators="" open="(" close=")"> <msub> <mi>x</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> <mo>,</mo> <msub> <mi>x</mi> <mn>2</mn> </msub> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> </mfenced> <mo>=</mo> <mfenced separators="" open="(" close=")"> <mn>0</mn> <mo>,</mo> <mn>0</mn> </mfenced> </mrow> </semantics></math>.</p>
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<p>Phase portraits for the fractional generalized Hénon map with <math display="inline"><semantics> <mrow> <mfenced separators="" open="(" close=")"> <msub> <mi>a</mi> <mn>2</mn> </msub> <mo>,</mo> <mspace width="4.pt"/> <msub> <mi>b</mi> <mn>2</mn> </msub> </mfenced> <mo>=</mo> <mfenced separators="" open="(" close=")"> <mn>0.99</mn> <mo>,</mo> <mspace width="4.pt"/> <mn>0.2</mn> </mfenced> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>υ</mi> <mo>=</mo> <mn>0.984</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mfenced separators="" open="(" close=")"> <msub> <mi>y</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> <mo>,</mo> <msub> <mi>y</mi> <mn>2</mn> </msub> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> <mo>,</mo> <msub> <mi>y</mi> <mn>3</mn> </msub> <mrow> <mo>(</mo> <mn>0</mn> <mo>)</mo> </mrow> </mfenced> <mo>=</mo> <mfenced separators="" open="(" close=")"> <mn>0.1</mn> <mo>,</mo> <mn>0.2</mn> <mo>,</mo> <mn>0.5</mn> </mfenced> </mrow> </semantics></math>.</p>
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<p>The evolution of errors over time for Example 1.</p>
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<p>The evolution of errors over time for Example 2.</p>
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23 pages, 11259 KiB  
Article
Strange Attractors Generated by Multiple-Valued Static Memory Cell with Polynomial Approximation of Resonant Tunneling Diodes
by Jiri Petrzela
Entropy 2018, 20(9), 697; https://doi.org/10.3390/e20090697 - 12 Sep 2018
Cited by 22 | Viewed by 4986
Abstract
This paper brings analysis of the multiple-valued memory system (MVMS) composed by a pair of the resonant tunneling diodes (RTD). Ampere-voltage characteristic (AVC) of both diodes is approximated in operational voltage range as common in practice: by polynomial scalar function. Mathematical model of [...] Read more.
This paper brings analysis of the multiple-valued memory system (MVMS) composed by a pair of the resonant tunneling diodes (RTD). Ampere-voltage characteristic (AVC) of both diodes is approximated in operational voltage range as common in practice: by polynomial scalar function. Mathematical model of MVMS represents autonomous deterministic dynamical system with three degrees of freedom and smooth vector field. Based on the very recent results achieved for piecewise-linear MVMS numerical values of the parameters are calculated such that funnel and double spiral chaotic attractor is observed. Existence of such types of strange attractors is proved both numerically by using concept of the largest Lyapunov exponents (LLE) and experimentally by computer-aided simulation of designed lumped circuit using only commercially available active elements. Full article
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<p>Basic network configurations of MVMS: original (<b>left</b> schematic), dual (<b>right</b> schematic).</p>
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<p>Three-dimensional perspective views on a typical chaotic attractor generated by polynomial MVMS for the initial conditions <b>x</b><sub>0</sub> = (0.1, 0.3, 0)<sup>T</sup>; Poincaré sections in planes shifted by the offsets of polynomial functions: <span class="html-italic">x</span> = <span class="html-italic">c</span><sub>1</sub> (red), <span class="html-italic">y</span> = <span class="html-italic">c</span><sub>2</sub> (yellow); fixed point of the flow (blue dots), state space rotation (no deformations of axis system). Numerical integration with final time 10<sup>4</sup> and time step 0.01.</p>
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<p>Three-dimensional perspective views on chaotic attractor with increased entropy generated by polynomial MVMS for the initial conditions <b>x</b><sub>0</sub> = (0.1, 0.3, 0)<sup>T</sup>; Poincaré sections in planes shifted by offsets of polynomial functions: <span class="html-italic">x</span> = <span class="html-italic">c</span><sub>1</sub> (red), <span class="html-italic">y</span> = <span class="html-italic">c</span><sub>2</sub> (yellow); fixed point of the flow (blue dots), state space rotation (no deformations of axis system). Calculation with final time 10<sup>4</sup> and time step 0.01.</p>
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<p>Important geometric structures located within state space: <span class="html-italic">v</span><sub>1</sub>–<span class="html-italic">v</span><sub>2</sub> plane projection of function <span class="html-italic">f</span><sub>1</sub>(<span class="html-italic">v</span><sub>1</sub>) (orange), function <span class="html-italic">f</span><sub>2</sub>(<span class="html-italic">v</span><sub>2</sub>) (green) and <span class="html-italic">v</span><sub>1</sub> = <span class="html-italic">V<sub>bias</sub></span> − <span class="html-italic">v</span><sub>2</sub> (blue line), intersections of these planes are fixed points of dynamical flow. Discovered chaotic attractor put into the context of vector field.</p>
Full article ">Figure 5
<p>Graphical visualization of a dynamical behavior near the fixed points (red dots): equilibrium <span class="html-italic">x<sub>e</sub></span> = 0.046 (left two images), for fixed point located at <span class="html-italic">x<sub>e</sub></span> = 0.292 (middle two plots) and fixed point with <span class="html-italic">x<sub>e</sub></span> = 0.55 (right two state portraits).</p>
Full article ">Figure 6
<p>Gallery of one-dimensional bifurcation diagrams calculated with respect to the polynomial approximation of AVCs of RTDs; individual plots from left to right: horizontal axis represented by parameter range <span class="html-italic">a</span><sub>1</sub> ∈ (600, 700) calculated with step Δ = 0.1; parameter range <span class="html-italic">b</span><sub>1</sub> ∈ (−30, 0) established with step Δ = 0.01; parameter range <span class="html-italic">c</span><sub>1</sub> ∈ (−1.5, 0) together with step Δ = 0.001; parameter <span class="html-italic">a</span><sub>2</sub> ∈ (30, 100) with step Δ = 0.1; parameter <span class="html-italic">b</span><sub>2</sub> ∈ (−25, −20) together with step Δ = 0.01 and parameter <span class="html-italic">c</span><sub>2</sub> ∈ (−4, 0) with step Δ = 0.01.</p>
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<p>Rainbow-scaled contour plots of short-time evolution of MVMS energy for the state space slices forming unity cube (left to right): <span class="html-italic">z</span><sub>0</sub> = −5, <span class="html-italic">z</span><sub>0</sub> = −4, <span class="html-italic">z</span><sub>0</sub> = −3, <span class="html-italic">z</span><sub>0</sub> = −2, <span class="html-italic">z</span><sub>0</sub> = −1, <span class="html-italic">z</span><sub>0</sub> = 0, <span class="html-italic">z</span><sub>0</sub> = 1, <span class="html-italic">z</span><sub>0</sub> = 2, <span class="html-italic">z</span><sub>0</sub> = 3, <span class="html-italic">z</span><sub>0</sub> = 4, <span class="html-italic">z</span><sub>0</sub> = 5.</p>
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<p>Gallery of the rainbow-scaled surface-contour plots of LLE as functions of two parameters; vertical range dedicated for LLE is −0.004 to 0.103, counting of plots from left to right and up to down: <span class="html-italic">a</span><sub>1</sub>–<span class="html-italic">b</span><sub>1</sub>, <span class="html-italic">a</span><sub>1</sub>–<span class="html-italic">c</span><sub>1</sub>, <span class="html-italic">a</span><sub>1</sub>–<span class="html-italic">a</span><sub>2</sub>, <span class="html-italic">a</span><sub>1</sub>–<span class="html-italic">b</span><sub>2</sub>, <span class="html-italic">a</span><sub>1</sub>–<span class="html-italic">c</span><sub>2</sub>, <span class="html-italic">b</span><sub>1</sub>–<span class="html-italic">c</span><sub>1</sub>, <span class="html-italic">b</span><sub>1</sub>–<span class="html-italic">a</span><sub>2</sub>, <span class="html-italic">b</span><sub>1</sub>–<span class="html-italic">b</span><sub>2</sub>, <span class="html-italic">b</span><sub>1</sub>–<span class="html-italic">c</span><sub>2</sub>, <span class="html-italic">c</span><sub>1</sub>–<span class="html-italic">a</span><sub>2</sub>, <span class="html-italic">c</span><sub>1</sub>–<span class="html-italic">b</span><sub>2</sub>, <span class="html-italic">c</span><sub>1</sub>–<span class="html-italic">c</span><sub>2</sub>, <span class="html-italic">a</span><sub>2</sub>–<span class="html-italic">b</span><sub>2</sub>, <span class="html-italic">a</span><sub>2</sub>–<span class="html-italic">c</span><sub>2</sub>, <span class="html-italic">b</span><sub>2</sub>–<span class="html-italic">c</span><sub>2</sub>.</p>
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<p>Chaotic oscillator designed to audio band based on integrator block schematic associated with mathematical model of MVMS, numerical values of passive network components are included.</p>
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<p>Chaotic system obtained directly from fundamental MVMS with ideal multipliers and ideal second-generation current-conveyors, numerical values of the circuit components are included.</p>
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<p>Chaotic system obtained directly from fundamental MVMS network with floating synthetic inductor, numerical values of the passive circuit components are included, ready for verification.</p>
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<p>Hypothetic analog circuit realization dual to original MVMS network with ideal controlled sources: trans-resistance of output current-to-voltage conversion is considered as global parameter.</p>
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<p>Orcad Pspice optimization toolbox: definitions of the objective functions and requested maximal errors (upper right field), error graph (upper left), new values of resistors (middle table).</p>
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<p>Orcad Pspice circuit simulation associated with chaotic circuit given in <a href="#entropy-20-00697-f009" class="html-fig">Figure 9</a>: selected plane projection <span class="html-italic">v</span><sub>3</sub>–<span class="html-italic">v</span><sub>2</sub> (blue, upper graph), <span class="html-italic">v</span><sub>2</sub>–<span class="html-italic">v</span><sub>1</sub> (red) and <span class="html-italic">v</span><sub>3</sub>–<span class="html-italic">v</span><sub>1</sub> (blue) of the chaotic attractor, generated chaotic signal <span class="html-italic">v</span><sub>1</sub> (red) and <span class="html-italic">v</span><sub>2</sub> (blue) in the time domain, chaotic waveform <span class="html-italic">v</span><sub>1</sub> (red) and <span class="html-italic">v</span><sub>2</sub> (blue) in the frequency domain. Note that significant frequency components are concentrated in audio range.</p>
Full article ">Figure 15
<p>Orcad Pspice circuit simulation associated with network given in <a href="#entropy-20-00697-f010" class="html-fig">Figure 10</a>: selected plane projection <span class="html-italic">v</span><sub>1</sub>–<span class="html-italic">v</span><sub>2</sub> (blue, upper plot), <span class="html-italic">v</span><sub>1</sub>–<span class="html-italic">i</span><sub>L</sub> (red) and <span class="html-italic">v</span><sub>2</sub>–<span class="html-italic">i</span><sub>L</sub> (blue) of chaotic attractor, generated signal <span class="html-italic">v</span><sub>1</sub> (red) and <span class="html-italic">v</span><sub>2</sub> (blue) in time domain, chaotic waveform <span class="html-italic">v</span><sub>1</sub> (red) and <span class="html-italic">v</span><sub>2</sub> (blue) in frequency domain.</p>
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<p>Orcad Pspice circuit simulation associated with network given in <a href="#entropy-20-00697-f010" class="html-fig">Figure 10</a>: plane projection <span class="html-italic">v<sub>Z</sub></span>–<span class="html-italic">i<sub>L</sub></span><sub>2</sub> (blue, upper plot), <span class="html-italic">i<sub>L</sub></span><sub>2</sub>–<span class="html-italic">i<sub>L</sub></span><sub>1</sub> (red) and <span class="html-italic">v<sub>Z</sub></span>–<span class="html-italic">i<sub>L</sub></span><sub>1</sub> (blue) of the observed strange attractor, generated chaotic signal <span class="html-italic">i<sub>L</sub></span><sub>2</sub> (red) and <span class="html-italic">v<sub>Z</sub></span> (blue) in the time domain, chaotic waveform <span class="html-italic">i<sub>L</sub></span><sub>2</sub> (red) and <span class="html-italic">v<sub>Z</sub></span> (blue) in the frequency domain. Note that generated chaos is not affected by saturation levels of the active devices.</p>
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<p>Practical realization of the integrator-based chaotic MVMS using bread-board.</p>
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<p>Selected chaotic waveforms in time domain generated by integrator-based MVMS.</p>
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<p>Selected <span class="html-italic">v</span><sub>3</sub>–<span class="html-italic">v</span><sub>2</sub> plane projections measured of integrator-based MVMS realization, see text.</p>
Full article ">Figure 20
<p>Few selected <span class="html-italic">v</span><sub>3</sub>–<span class="html-italic">v</span><sub>1</sub> plane projections measured within dynamics of the integrator-based implementation MVMS, voltage sources <span class="html-italic">V<sub>c</sub></span><sub>1</sub> and <span class="html-italic">V<sub>c</sub></span><sub>2</sub> are swept, i.e., system parameters <span class="html-italic">c</span><sub>1</sub> and <span class="html-italic">c</span><sub>2</sub> are considered as variable parameters, change of the voltages starts within bifurcation diagrams provided by means of <a href="#entropy-20-00697-f006" class="html-fig">Figure 6</a> but finally goes far beyond it.</p>
Full article ">Figure 21
<p>Gallery of interesting (still robust and real-time observable) strange attractors generated by the integrator-based realization of MVMS, different plane projections, see text for details.</p>
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10 pages, 434 KiB  
Article
Optimization of Thurston’s Core Entropy Algorithm for Polynomials with a Critical Point of Maximal Order
by Gamaliel Blé and Domingo González
Entropy 2018, 20(9), 695; https://doi.org/10.3390/e20090695 - 11 Sep 2018
Cited by 1 | Viewed by 3225
Abstract
This paper discusses some properties of the topological entropy systems generated by polynomials of degree d in their Hubbard tree. An optimization of Thurston’s core entropy algorithm is developed for a family of polynomials of degree d. Full article
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Figure 1

Figure 1
<p>Julia set and critical portrait for <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1.07183814</mn> <mo>+</mo> <mn>0.1928507</mn> <mi>i</mi> </mrow> </semantics></math>.</p>
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<p>Restricted critical portrait for <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1.07183814</mn> <mo>+</mo> <mn>0.1928507</mn> <mi>i</mi> </mrow> </semantics></math>.</p>
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<p>Core entropy for <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>.</p>
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12 pages, 3930 KiB  
Article
A New Chaotic System with Stable Equilibrium: Entropy Analysis, Parameter Estimation, and Circuit Design
by Tomasz Kapitaniak, S. Alireza Mohammadi, Saad Mekhilef, Fawaz E. Alsaadi, Tasawar Hayat and Viet-Thanh Pham
Entropy 2018, 20(9), 670; https://doi.org/10.3390/e20090670 - 5 Sep 2018
Cited by 30 | Viewed by 4670
Abstract
In this paper, we introduce a new, three-dimensional chaotic system with one stable equilibrium. This system is a multistable dynamic system in which the strange attractor is hidden. We investigate its dynamic properties through equilibrium analysis, a bifurcation diagram and Lyapunov exponents. Such [...] Read more.
In this paper, we introduce a new, three-dimensional chaotic system with one stable equilibrium. This system is a multistable dynamic system in which the strange attractor is hidden. We investigate its dynamic properties through equilibrium analysis, a bifurcation diagram and Lyapunov exponents. Such multistable systems are important in engineering. We perform an entropy analysis, parameter estimation and circuit design using this new system to show its feasibility and ability to be used in engineering applications. Full article
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Figure 1

Figure 1
<p>Time series of System (1) with parameter <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial conditions <math display="inline"><semantics> <mrow> <mrow> <mo stretchy="false">(</mo> <mrow> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> </mrow> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <mrow> <mo stretchy="false">(</mo> <mrow> <mn>5.4</mn> <mo>,</mo> <mtext> </mtext> <mo>−</mo> <mn>1.8</mn> <mo>,</mo> <mtext> </mtext> <mn>3.3</mn> </mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </semantics></math>.</p>
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<p>Three projections of the chaotic attractor of System (1) with parameter <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial conditions <math display="inline"><semantics> <mrow> <mrow> <mo stretchy="false">(</mo> <mrow> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> </mrow> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <mrow> <mo stretchy="false">(</mo> <mrow> <mn>5.4</mn> <mo>,</mo> <mtext> </mtext> <mo>−</mo> <mn>1.8</mn> <mo>,</mo> <mtext> </mtext> <mn>3.3</mn> </mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </semantics></math> in (<b>a</b>) <span class="html-italic">X-Y</span> plane. (<b>b</b>) <span class="html-italic">X-Z</span> plane. (<b>c</b>) <span class="html-italic">Y-Z</span> plane and (<b>d</b>) 3-D chaotic attractor.</p>
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<p>Poincaré map (peaks of <span class="html-italic">x</span> variable) of System (1) with parameter <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and initial conditions <math display="inline"><semantics> <mrow> <mrow> <mo stretchy="false">(</mo> <mrow> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> </mrow> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <mrow> <mo stretchy="false">(</mo> <mrow> <mn>5.4</mn> <mo>,</mo> <mtext> </mtext> <mo>−</mo> <mn>1.8</mn> <mo>,</mo> <mtext> </mtext> <mn>3.3</mn> </mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </semantics></math>.</p>
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<p>(<b>a</b>) Bifurcation diagram of System (1) with respect to the changing parameter <span class="html-italic">a</span> in the interval [1, 1.5] and forward continuation. (<b>b</b>) Lyapunov exponents of System (1) with respect to the changing parameter <span class="html-italic">a</span> in the interval [1, 1.5] and forward continuation.</p>
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<p>Kolmogorov–Sinai entropy of System (1) with respect to changing parameter <span class="html-italic">a</span>.</p>
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<p>The value of the cost function with respect to changing the parameter <span class="html-italic">a</span>.</p>
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<p>The value of the cost function with respect to changing the parameter <span class="html-italic">a</span> &amp; <span class="html-italic">b</span>.</p>
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<p>The result of WOA for the 30 searching agents and 40 iterations.</p>
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<p>The circuit constructed by six operational amplifiers <math display="inline"><semantics> <mrow> <mrow> <mo stretchy="false">(</mo> <mrow> <msub> <mi>U</mi> <mn>1</mn> </msub> <mo>−</mo> <msub> <mi>U</mi> <mn>6</mn> </msub> </mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </semantics></math> and electronic elements.</p>
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<p>Generated attractors in PSpice of the circuit: (<b>a</b>) <span class="html-italic">X</span>-<span class="html-italic">Y</span> plane, (<b>b</b>) <span class="html-italic">X</span>-<span class="html-italic">Z</span> plane, (<b>c</b>) <span class="html-italic">Y</span>-<span class="html-italic">Z</span> plane.</p>
Full article ">
18 pages, 12752 KiB  
Article
A New Fractional-Order Chaotic System with Different Families of Hidden and Self-Excited Attractors
by Jesus M. Munoz-Pacheco, Ernesto Zambrano-Serrano, Christos Volos, Sajad Jafari, Jacques Kengne and Karthikeyan Rajagopal
Entropy 2018, 20(8), 564; https://doi.org/10.3390/e20080564 - 28 Jul 2018
Cited by 74 | Viewed by 5541
Abstract
In this work, a new fractional-order chaotic system with a single parameter and four nonlinearities is introduced. One striking feature is that by varying the system parameter, the fractional-order system generates several complex dynamics: self-excited attractors, hidden attractors, and the coexistence of hidden [...] Read more.
In this work, a new fractional-order chaotic system with a single parameter and four nonlinearities is introduced. One striking feature is that by varying the system parameter, the fractional-order system generates several complex dynamics: self-excited attractors, hidden attractors, and the coexistence of hidden attractors. In the family of self-excited chaotic attractors, the system has four spiral-saddle-type equilibrium points, or two nonhyperbolic equilibria. Besides, for a certain value of the parameter, a fractional-order no-equilibrium system is obtained. This no-equilibrium system presents a hidden chaotic attractor with a `hurricane’-like shape in the phase space. Multistability is also observed, since a hidden chaotic attractor coexists with a periodic one. The chaos generation in the new fractional-order system is demonstrated by the Lyapunov exponents method and equilibrium stability. Moreover, the complexity of the self-excited and hidden chaotic attractors is analyzed by computing their spectral entropy and Brownian-like motions. Finally, a pseudo-random number generator is designed using the hidden dynamics. Full article
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Figure 1

Figure 1
<p>Self-excited attractor of the system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>) considering <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mo>−</mo> <mn>1</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.93</mn> </mrow> </semantics></math>. (<b>a</b>) x–y plane; (<b>b</b>) x–z plane; (<b>c</b>) y–z plane.</p>
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<p>Chaotic attractor of the system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>) with nonhyperbolic equilibrium points, <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.25</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.99</mn> </mrow> </semantics></math>. (<b>a</b>) x–y plane; (<b>b</b>) x–z plane; (<b>c</b>) y–z plane.</p>
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<p>(<b>a</b>) Lyapunov exponents spectrum, and (<b>b</b>) bifurcation diagram of the fractional-order nonhyperbolic system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>) when <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> <mo>/</mo> <mn>4</mn> </mrow> </semantics></math>.</p>
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<p>Hidden attractor of the system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>) considering <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.35</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.97</mn> </mrow> </semantics></math>, and initial conditions <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>x</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>,</mo> <mi>y</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>,</mo> <mi>z</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>)</mo> <mo>=</mo> <mo>(</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>)</mo> </mrow> </semantics></math>. (<b>a</b>) x–y plane; (<b>b</b>) x–z plane; (<b>c</b>) y–z plane.</p>
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<p>(<b>a</b>) Lyapunov exponents spectrum, and (<b>b</b>) bifurcation diagram of the fractional-order no-equilibrium system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>), when <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>&gt;</mo> <mn>1</mn> <mo>/</mo> <mn>4</mn> </mrow> </semantics></math>.</p>
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<p>Cross-section of the basins of attraction of the two coexisting attractors in the y–z plane at <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math> for the fractional-order chaotic system without equilibrium (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>) when <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.35</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.996</mn> </mrow> </semantics></math>.</p>
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<p>Coexistence of hidden chaotic and periodic attractors of the system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>) considering <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.35</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.996</mn> </mrow> </semantics></math>. (<b>a</b>) x–y plane; (<b>b</b>) x–z plane; (<b>c</b>) y–z plane.</p>
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<p>Hidden periodic attractor of the fractional-order system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>) with <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.35</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.996</mn> </mrow> </semantics></math>, and initial conditions <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>x</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>,</mo> <mi>y</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>,</mo> <mi>z</mi> <mo>(</mo> <mn>0</mn> <mo>)</mo> <mo>)</mo> <mo>=</mo> <mo>(</mo> <mn>0</mn> <mo>,</mo> <mn>75</mn> <mo>,</mo> <mo>−</mo> <mn>50</mn> <mo>)</mo> </mrow> </semantics></math>. (<b>a</b>) x–y plane; (<b>b</b>) x–z plane; (<b>c</b>) y–z plane.</p>
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<p>Bi-dimensional map for the different dynamical behaviors of the fractional-order system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>) as a function of the parameter <span class="html-italic">a</span> and order <span class="html-italic">q</span>. The white region leads to a chaotic attractor, the black region evolves to periodic attractors, and the orange region converges to unbounded orbits. Self-excited, nonhyperbolic, and hidden chaotic attractors for <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>&lt;</mo> <mn>1</mn> <mo>/</mo> <mn>4</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>1</mn> <mo>/</mo> <mn>4</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>&gt;</mo> <mn>1</mn> <mo>/</mo> <mn>4</mn> </mrow> </semantics></math>, respectively.</p>
Full article ">Figure 10
<p>Dynamics of the translation components <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>p</mi> <mn>1</mn> </msub> <mo>,</mo> <msub> <mi>p</mi> <mn>2</mn> </msub> <mo>)</mo> </mrow> </semantics></math> of the fractional-order system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>): (<b>a</b>) Self-excited chaotic attractor (<math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.93</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mo>−</mo> <mn>1</mn> </mrow> </semantics></math>) with an asymptotic growth rate <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>0.9988</mn> </mrow> </semantics></math>; (<b>b</b>) hidden chaotic attractor (<math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.97</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.35</mn> </mrow> </semantics></math>), with <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>0.9985</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 11
<p>Dynamics of the translation components <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>p</mi> <mn>1</mn> </msub> <mo>,</mo> <msub> <mi>p</mi> <mn>2</mn> </msub> <mo>)</mo> </mrow> </semantics></math> of the fractional-order system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>): (<b>a</b>) Coexisting hidden chaotic attractor (<math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.996</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.35</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>,</mo> <mi>z</mi> <mo>)</mo> <mo>=</mo> <mo>(</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>)</mo> </mrow> </semantics></math>) with an asymptotic growth rate <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>0.9975</mn> </mrow> </semantics></math>; (<b>b</b>) coexisting hidden periodic attractor (<math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>0.996</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.35</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>,</mo> <mi>z</mi> <mo>)</mo> <mo>=</mo> <mo>(</mo> <mn>0</mn> <mo>,</mo> <mn>75</mn> <mo>,</mo> <mo>−</mo> <mn>50</mn> <mo>)</mo> </mrow> </semantics></math> with <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>0.0364</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 12
<p>Spectral entropy versus fractional-order <span class="html-italic">q</span> for the system (<a href="#FD15-entropy-20-00564" class="html-disp-formula">15</a>): (<b>a</b>) Structural complexity of the self-excited attractor in <a href="#entropy-20-00564-f001" class="html-fig">Figure 1</a> (<math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mo>−</mo> <mn>1</mn> </mrow> </semantics></math>); (<b>b</b>) structural complexity of the hidden chaotic attractor in <a href="#entropy-20-00564-f004" class="html-fig">Figure 4</a> (<math display="inline"><semantics> <mrow> <mi>a</mi> <mo>=</mo> <mn>0.35</mn> </mrow> </semantics></math>).</p>
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14 pages, 9380 KiB  
Article
Multivariate Multiscale Complexity Analysis of Self-Reproducing Chaotic Systems
by Shaobo He, Chunbiao Li, Kehui Sun and Sajad Jafari
Entropy 2018, 20(8), 556; https://doi.org/10.3390/e20080556 - 27 Jul 2018
Cited by 46 | Viewed by 3705
Abstract
Designing a chaotic system with infinitely many attractors is a hot topic. In this paper, multiscale multivariate permutation entropy (MMPE) and multiscale multivariate Lempel–Ziv complexity (MMLZC) are employed to analyze the complexity of those self-reproducing chaotic systems with one-directional and two-directional infinitely many [...] Read more.
Designing a chaotic system with infinitely many attractors is a hot topic. In this paper, multiscale multivariate permutation entropy (MMPE) and multiscale multivariate Lempel–Ziv complexity (MMLZC) are employed to analyze the complexity of those self-reproducing chaotic systems with one-directional and two-directional infinitely many chaotic attractors. The analysis results show that complexity of this class of chaotic systems is determined by the initial conditions. Meanwhile, the values of MMPE are independent of the scale factor, which is different from the algorithm of MMLZC. The analysis proposed here is helpful as a reference for the application of the self-reproducing systems. Full article
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Figure 1

Figure 1
<p>Steps to analyze the complexity of a chaotic system through the multiscale multivariate Lempel–Ziv complexity (MMLZC) and multiscale multivariate permutation entropy (MMPE) and algorithms. (<b>a</b>) Chaotic systems; (<b>b</b>) Chaotic time series; (<b>c</b>) Permutation Vector Discretization; (<b>d</b>) Measuring complexity based on <math display="inline"><semantics> <mo>Φ</mo> </semantics></math>; (<b>e</b>) Show the results.</p>
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<p>Coexisting attractors and complexity analysis results of System (13). (<b>a</b>) Coexisting attractors; (<b>b</b>) MMLZC; (<b>c</b>) MMPE; (<b>d</b>) MMLZC-MMPE plot.</p>
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<p>Complexity analysis result and mean value of <span class="html-italic">x</span> of System (13).</p>
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<p>Coexisting attractors and complexity analysis results of System (14). (<b>a</b>) Coexisting attractors; (<b>b</b>) MMLZC; (<b>c</b>) MMPE; (<b>d</b>) MMLZC-MMPE plot.</p>
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<p>Complexity analysis results of System (14) with simultaneous variations of <math display="inline"><semantics> <msub> <mi>x</mi> <mn>0</mn> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>y</mi> <mn>0</mn> </msub> </semantics></math>. (<b>a</b>) MMPE analysis result; (<b>b</b>) MMLZC analysis result.</p>
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<p>Coexisting attractors of System (15) with different initial conditions.</p>
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<p>Complexity analysis results of System (15). (<b>a</b>) MMPE with <math display="inline"><semantics> <msub> <mi>y</mi> <mn>0</mn> </msub> </semantics></math> and <span class="html-italic">b</span>; (<b>b</b>) MMPE with <math display="inline"><semantics> <msub> <mi>y</mi> <mn>0</mn> </msub> </semantics></math> and <span class="html-italic">b</span>; (<b>c</b>) MMPE with <math display="inline"><semantics> <msub> <mi>y</mi> <mn>0</mn> </msub> </semantics></math> and <span class="html-italic">b</span>; (<b>d</b>) MMLZC with <math display="inline"><semantics> <msub> <mi>z</mi> <mn>0</mn> </msub> </semantics></math> and <span class="html-italic">b</span>.</p>
Full article ">Figure 8
<p>Complexity of System (15) with both <math display="inline"><semantics> <msub> <mi>y</mi> <mn>0</mn> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>z</mi> <mn>0</mn> </msub> </semantics></math> varying. (<b>a</b>) MMPE; (<b>b</b>) MMLZC.</p>
Full article ">Figure 9
<p>Dynamics of System (15) with <math display="inline"><semantics> <mrow> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>y</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>z</mi> <mn>0</mn> </msub> <mo>)</mo> </mrow> <mo>=</mo> <mrow> <mo>(</mo> <mn>0</mn> <mo>,</mo> <mn>0.1</mn> <mo>−</mo> <mn>82</mn> <mi>π</mi> <mo>,</mo> <mo>−</mo> <mn>82</mn> <mi>π</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>. (<b>a</b>) Phase diagram; (<b>b</b>) time series <span class="html-italic">x</span>; (<b>c</b>) time series <span class="html-italic">y</span>; (<b>d</b>) time series <span class="html-italic">z</span>.</p>
Full article ">Figure 10
<p>States of System (15) under different scale factors. (<b>a</b>) Phase diagram under <math display="inline"><semantics> <mrow> <mi>τ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>; (<b>b</b>) quantification pattern series under <math display="inline"><semantics> <mrow> <mi>τ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>; (<b>c</b>) probability distribution under <math display="inline"><semantics> <mrow> <mi>τ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>; (<b>d</b>) phase diagram under <math display="inline"><semantics> <mrow> <mi>τ</mi> <mo>=</mo> <mn>50</mn> </mrow> </semantics></math>; (<b>e</b>) quantification pattern series under <math display="inline"><semantics> <mrow> <mi>τ</mi> <mo>=</mo> <mn>50</mn> </mrow> </semantics></math>; (<b>f</b>) probability distribution under <math display="inline"><semantics> <mrow> <mi>τ</mi> <mo>=</mo> <mn>50</mn> </mrow> </semantics></math>; (<b>g</b>) phase diagram under <math display="inline"><semantics> <mrow> <mi>τ</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>; (<b>h</b>) quantification pattern series under <math display="inline"><semantics> <mrow> <mi>τ</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>; (<b>i</b>) probability distribution under <math display="inline"><semantics> <mrow> <mi>τ</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>.</p>
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17 pages, 347 KiB  
Article
Stochastic Entropy Solutions for Stochastic Nonlinear Transport Equations
by Rongrong Tian and Yanbin Tang
Entropy 2018, 20(6), 395; https://doi.org/10.3390/e20060395 - 23 May 2018
Cited by 6 | Viewed by 2623
Abstract
This paper considers the existence and uniqueness of stochastic entropy solution for a nonlinear transport equation with a stochastic perturbation. The uniqueness is based on the doubling variable method. For the existence, we develop a new scheme of parabolic approximation motivated by the [...] Read more.
This paper considers the existence and uniqueness of stochastic entropy solution for a nonlinear transport equation with a stochastic perturbation. The uniqueness is based on the doubling variable method. For the existence, we develop a new scheme of parabolic approximation motivated by the method of vanishing viscosity given by Feng and Nualart (J. Funct. Anal. 2008, 255, 313–373). Furthermore, we prove the continuous dependence of stochastic strong entropy solutions on the coefficient b and the nonlinear function f. Full article
10 pages, 5288 KiB  
Article
A New Two-Dimensional Map with Hidden Attractors
by Chuanfu Wang and Qun Ding
Entropy 2018, 20(5), 322; https://doi.org/10.3390/e20050322 - 27 Apr 2018
Cited by 43 | Viewed by 4989
Abstract
The investigations of hidden attractors are mainly in continuous-time dynamic systems, and there are a few investigations of hidden attractors in discrete-time dynamic systems. The classical chaotic attractors of the Logistic map, Tent map, Henon map, Arnold’s cat map, and other widely-known chaotic [...] Read more.
The investigations of hidden attractors are mainly in continuous-time dynamic systems, and there are a few investigations of hidden attractors in discrete-time dynamic systems. The classical chaotic attractors of the Logistic map, Tent map, Henon map, Arnold’s cat map, and other widely-known chaotic attractors are those excited from unstable fixed points. In this paper, the hidden dynamics of a new two-dimensional map inspired by Arnold’s cat map is investigated, and the existence of fixed points and their stabilities are studied in detail. Full article
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Figure 1

Figure 1
<p>When <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.7</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.6</mn> </mrow> </semantics></math>, this represents the phase diagram of Arnold’s cat map.</p>
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<p>When <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.7</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.6</mn> </mrow> </semantics></math>, the phase diagram of the new 2-D map with <math display="inline"><semantics> <mrow> <mi>a</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>3</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>c</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>d</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>e</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.1</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>f</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.2</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 3
<p>The plot of the output time series (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 4
<p>When <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.7</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.6</mn> </mrow> </semantics></math>, the phase diagram of the new 2-D map with <math display="inline"><semantics> <mrow> <mi>a</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>3.2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>c</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>1.1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>d</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>e</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.1</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>f</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.2</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 5
<p>The plot of the output time series (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 6
<p>When <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.7</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mn>0</mn> <mo stretchy="false">)</mo> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.6</mn> </mrow> </semantics></math>, the phase diagram of the new 2-D map with <math display="inline"><semantics> <mrow> <mi>a</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>b</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>c</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mo>−</mo> <mn>0.25</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>d</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>e</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.1</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>f</mi> <mtext> </mtext> <mo>=</mo> <mtext> </mtext> <mn>0.2</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 7
<p>The plot of the output time series (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
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<p>The block diagram of the hardware implementation by FPGA.</p>
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14 pages, 4904 KiB  
Article
A Novel Algorithm to Improve Digital Chaotic Sequence Complexity through CCEMD and PE
by Chunlei Fan, Zhigang Xie and Qun Ding
Entropy 2018, 20(4), 295; https://doi.org/10.3390/e20040295 - 18 Apr 2018
Cited by 7 | Viewed by 4196
Abstract
In this paper, a three-dimensional chaotic system with a hidden attractor is introduced. The complex dynamic behaviors of the system are analyzed with a Poincaré cross section, and the equilibria and initial value sensitivity are analyzed by the method of numerical simulation. Further, [...] Read more.
In this paper, a three-dimensional chaotic system with a hidden attractor is introduced. The complex dynamic behaviors of the system are analyzed with a Poincaré cross section, and the equilibria and initial value sensitivity are analyzed by the method of numerical simulation. Further, we designed a new algorithm based on complementary ensemble empirical mode decomposition (CEEMD) and permutation entropy (PE) that can effectively enhance digital chaotic sequence complexity. In addition, an image encryption experiment was performed with post-processing of the chaotic binary sequences by the new algorithm. The experimental results show good performance of the chaotic binary sequence. Full article
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Figure 1

Figure 1
<p>The different projections of chaotic attractor with: (<b>a</b>) <span class="html-italic">x</span>-<span class="html-italic">y</span>; (<b>b</b>) <span class="html-italic">x</span>-<span class="html-italic">z</span>; (<b>c</b>) <span class="html-italic">y</span>-<span class="html-italic">z</span>.</p>
Full article ">Figure 1 Cont.
<p>The different projections of chaotic attractor with: (<b>a</b>) <span class="html-italic">x</span>-<span class="html-italic">y</span>; (<b>b</b>) <span class="html-italic">x</span>-<span class="html-italic">z</span>; (<b>c</b>) <span class="html-italic">y</span>-<span class="html-italic">z</span>.</p>
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<p>Poincaré map in the <span class="html-italic">x</span>-<span class="html-italic">z</span> plane.</p>
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<p>Initial value sensitivity for the time series <math display="inline"><semantics> <mi>x</mi> </semantics></math> with the initial values (−1.6, 0.82, 1.9) and (−1.601, 0.82, 1.9).</p>
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<p>Chaotic time series with <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> (blue color), <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> (green color), and <math display="inline"><semantics> <mrow> <mi>z</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math> (red color).</p>
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<p>All the low complexity signals in the intrinsic mode functions (IMFs) with: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>z</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 6
<p>Time series after algorithm processing with: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>x</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>y</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>z</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
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<p>Permutation entropy (PE) value comparisons between the original signal and post-processing signal.</p>
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<p>Key sensitivity test with: (<b>a</b>) plain-image for Lena; (<b>b</b>) cipher-image for Lena; (<b>c</b>) incorrect decryption using a 10<sup>−5</sup> change of the initial value for Lena; (<b>d</b>) plain-image for Baboon; (<b>e</b>) cipher-image for Baboon; (<b>f</b>) incorrect decryption using a 10<sup>−5</sup> change of the initial value for Baboon.</p>
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<p>Histogram test with: (<b>a</b>) R component of the plain-image; (<b>b</b>) R component of the cipher-image; (<b>c</b>) B component of the plain-image; (<b>d</b>) B component of the cipher-image; (<b>e</b>) G component of the plain-image; (<b>f</b>) G component of the cipher-image.</p>
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23 pages, 8699 KiB  
Article
A New Chaotic System with a Self-Excited Attractor: Entropy Measurement, Signal Encryption, and Parameter Estimation
by Guanghui Xu, Yasser Shekofteh, Akif Akgül, Chunbiao Li and Shirin Panahi
Entropy 2018, 20(2), 86; https://doi.org/10.3390/e20020086 - 27 Jan 2018
Cited by 83 | Viewed by 7312
Abstract
In this paper, we introduce a new chaotic system that is used for an engineering application of the signal encryption. It has some interesting features, and its successful implementation and manufacturing were performed via a real circuit as a random number generator. In [...] Read more.
In this paper, we introduce a new chaotic system that is used for an engineering application of the signal encryption. It has some interesting features, and its successful implementation and manufacturing were performed via a real circuit as a random number generator. In addition, we provide a parameter estimation method to extract chaotic model parameters from the real data of the chaotic circuit. The parameter estimation method is based on the attractor distribution modeling in the state space, which is compatible with the chaotic system characteristics. Here, a Gaussian mixture model (GMM) is used as a main part of cost function computations in the parameter estimation method. To optimize the cost function, we also apply two recent efficient optimization methods: WOA (Whale Optimization Algorithm), and MVO (Multi-Verse Optimizer) algorithms. The results show the success of the parameter estimation procedure. Full article
Show Figures

Figure 1

Figure 1
<p>Different projections of the chaotic attractor of system (1) with the initial conditions <math display="inline"> <semantics> <mrow> <mrow> <mo>(</mo> <mrow> <mo>−</mo> <mn>1.8</mn> <mo>,</mo> <mtext> </mtext> <mo>−</mo> <mn>1.5</mn> <mo>,</mo> <mtext> </mtext> <mo>−</mo> <mn>2.5</mn> </mrow> <mo>)</mo> </mrow> </mrow> </semantics> </math>.</p>
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<p>(<b>A</b>) Bifurcation diagram of the system (1) with respect to parameter <math display="inline"> <semantics> <mi>g</mi> </semantics> </math>, and (<b>B</b>) Lyapunov exponents of the system (1) with respect to parameter <math display="inline"> <semantics> <mi>g</mi> </semantics> </math>.</p>
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<p>ApEn of the system (1) with respect to parameter <math display="inline"> <semantics> <mi>g</mi> </semantics> </math>.</p>
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<p>The general outlook of “Raspberry Pi 3”.</p>
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<p>Pins of <span class="html-italic">x</span>, <span class="html-italic">y</span> and <span class="html-italic">z</span> for chaotic system outputs from “Raspberry Pi 3”.</p>
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<p><span class="html-italic">x</span>, <span class="html-italic">y</span> and <span class="html-italic">z</span> outputs on the oscilloscope (first 50 bits).</p>
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<p>Original signal data (first 50 bits).</p>
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<p>Encrypted signal data (first 50 bits).</p>
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<p>Decrypted Signal Data (first 50 bits).</p>
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<p>The electronic circuit schematic of system (1).</p>
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<p>The experimental circuit of the chaotic circuit and the phase portraits of system (1) on the oscilloscope.</p>
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<p>The phase portraits of the system (1) in ORCAD-Pspice.</p>
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<p>The phase portraits of system (1) on the oscilloscope.</p>
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<p>Plot of the attractor and its GMM modeling with <math display="inline"> <semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>256</mn> </mrow> </semantics> </math> components for the chaotic system (1) with <math display="inline"> <semantics> <mrow> <mtext> </mtext> <mi>a</mi> <mo>=</mo> <mn>4</mn> <mtext> </mtext> <mo>&amp;</mo> <mtext> </mtext> <mi>b</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics> </math>, in the 3-D state space.</p>
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<p>Cost function versus parameter <span class="html-italic">a</span>, with different number GMM components (M) for the 1D parameter estimation method.</p>
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<p>Cost function versus parameter <span class="html-italic">b</span>, with different number of GMM components (M) for the 1D parameter estimation method.</p>
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<p>The contour plot of the GMM-based cost function for the introduced chaotic system (<math display="inline"> <semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>256</mn> </mrow> </semantics> </math>) along with variations in the parameters, <span class="html-italic">a</span>&amp;<span class="html-italic">b</span>.</p>
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<p>The “cost surface” of the GMM-based cost function for the introduced chaotic system (<math display="inline"> <semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>256</mn> </mrow> </semantics> </math>) along with variations in the parameters, <span class="html-italic">a</span>&amp;<span class="html-italic">b</span>.</p>
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<p>Comparison between the performances of the MVO and WOA optimization algorithm.</p>
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<p>Process of finding the best parameters using the WOA algorithm. (<b>a</b>–<b>d</b>) represent the first, 10th, 20th, and 30th iteration, respectively.</p>
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5274 KiB  
Article
A New Chaotic System with Multiple Attractors: Dynamic Analysis, Circuit Realization and S-Box Design
by Qiang Lai, Akif Akgul, Chunbiao Li, Guanghui Xu and Ünal Çavuşoğlu
Entropy 2018, 20(1), 12; https://doi.org/10.3390/e20010012 - 27 Dec 2017
Cited by 96 | Viewed by 7474
Abstract
This paper reports about a novel three-dimensional chaotic system with three nonlinearities. The system has one stable equilibrium, two stable equilibria and one saddle node, two saddle foci and one saddle node for different parameters. One salient feature of this novel system is [...] Read more.
This paper reports about a novel three-dimensional chaotic system with three nonlinearities. The system has one stable equilibrium, two stable equilibria and one saddle node, two saddle foci and one saddle node for different parameters. One salient feature of this novel system is its multiple attractors caused by different initial values. With the change of parameters, the system experiences mono-stability, bi-stability, mono-periodicity, bi-periodicity, one strange attractor, and two coexisting strange attractors. The complex dynamic behaviors of the system are revealed by analyzing the corresponding equilibria and using the numerical simulation method. In addition, an electronic circuit is given for implementing the chaotic attractors of the system. Using the new chaotic system, an S-Box is developed for cryptographic operations. Moreover, we test the performance of this produced S-Box and compare it to the existing S-Box studies. Full article
Show Figures

Figure 1

Figure 1
<p>The butterfly attractor of system (1): (<b>a</b>) <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics> </math>; (<b>b</b>) <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics> </math>; (<b>c</b>) <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics> </math>; (<b>d</b>) <math display="inline"> <semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics> </math>.</p>
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<p>The time series of variable <span class="html-italic">z</span> generated from initial conditions <math display="inline"> <semantics> <mrow> <mo>(</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>)</mo> </mrow> </semantics> </math> (red color) and <math display="inline"> <semantics> <mrow> <mo>(</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>1.001</mn> <mo>)</mo> </mrow> </semantics> </math> (blue color).</p>
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<p>The Poincaré maps of system (1) with crossing sections: (<b>a</b>) <math display="inline"> <semantics> <msub> <mo>Δ</mo> <mn>1</mn> </msub> </semantics> </math>; (<b>b</b>) <math display="inline"> <semantics> <msub> <mo>Δ</mo> <mn>2</mn> </msub> </semantics> </math>.</p>
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<p>The bifurcation diagrams (<b>a</b>) and Lyapunov exponents (<b>b</b>) of system (1) versus <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>∈</mo> <mo>(</mo> <mn>0</mn> <mo>,</mo> <mn>6</mn> <mo>)</mo> </mrow> </semantics> </math>.</p>
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<p>The phase portraits of system (1) with: (<b>a</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>0.8</mn> </mrow> </semantics> </math>; (<b>b</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>1.2</mn> </mrow> </semantics> </math>; (<b>c</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>1.4</mn> </mrow> </semantics> </math>; (<b>d</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>1.6</mn> </mrow> </semantics> </math>; (<b>e</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>2.9</mn> </mrow> </semantics> </math>; (<b>f</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>3.1</mn> </mrow> </semantics> </math>; (<b>g</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>3.2</mn> </mrow> </semantics> </math>; (<b>h</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>3.6</mn> </mrow> </semantics> </math>.</p>
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<p>The phase portraits of system (1) with: (<b>a</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>0.8</mn> </mrow> </semantics> </math>; (<b>b</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>1.2</mn> </mrow> </semantics> </math>; (<b>c</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>1.4</mn> </mrow> </semantics> </math>; (<b>d</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>1.6</mn> </mrow> </semantics> </math>; (<b>e</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>2.9</mn> </mrow> </semantics> </math>; (<b>f</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>3.1</mn> </mrow> </semantics> </math>; (<b>g</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>3.2</mn> </mrow> </semantics> </math>; (<b>h</b>) <math display="inline"> <semantics> <mrow> <mi>c</mi> <mo>=</mo> <mn>3.6</mn> </mrow> </semantics> </math>.</p>
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<p>The bifurcation diagrams (<b>a</b>) and Lyapunov exponents (<b>b</b>) of system (1) versus <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>∈</mo> <mo>(</mo> <mn>5</mn> <mo>,</mo> <mn>25</mn> <mo>)</mo> </mrow> </semantics> </math>.</p>
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<p>The phase portraits of system (1) with: (<b>a</b>) <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>5</mn> </mrow> </semantics> </math>; (<b>b</b>) <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>15</mn> </mrow> </semantics> </math>; (<b>c</b>) <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>18</mn> </mrow> </semantics> </math>; (<b>d</b>) <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>25</mn> </mrow> </semantics> </math>.</p>
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<p>The coexisting attractors of system (1): (<b>a</b>) projections on <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics> </math> with <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>19</mn> </mrow> </semantics> </math>; (<b>b</b>) time series of <span class="html-italic">y</span> with <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>19</mn> </mrow> </semantics> </math>; (<b>c</b>) projections on <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics> </math> with <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics> </math>; (<b>d</b>) time series of <span class="html-italic">y</span> with <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics> </math>.</p>
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<p>The phase portraits of the scaled system (8) for <math display="inline"> <semantics> <mrow> <mo>(</mo> <mi>a</mi> <mo>,</mo> <mi>b</mi> <mo>,</mo> <mi>c</mi> <mo>,</mo> <mi>k</mi> <mo>)</mo> <mo>=</mo> <mo>(</mo> <mn>2</mn> <mo>,</mo> <mn>8</mn> <mo>,</mo> <mn>2.9</mn> <mo>,</mo> <mn>4</mn> <mo>)</mo> </mrow> </semantics> </math>: (<b>a</b>) <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics> </math>; (<b>b</b>) <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics> </math>; (<b>c</b>) <math display="inline"> <semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics> </math>.</p>
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<p>The circuit diagram of system (8).</p>
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<p>The experimental circuit of system (8).</p>
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<p>The phase portraits of two coexisting attractors of system (8) on the oscilloscope for <math display="inline"> <semantics> <mrow> <mo>(</mo> <mi>a</mi> <mo>,</mo> <mi>b</mi> <mo>,</mo> <mi>c</mi> <mo>,</mo> <mi>k</mi> <mo>)</mo> <mo>=</mo> <mo>(</mo> <mn>2</mn> <mo>,</mo> <mn>8</mn> <mo>,</mo> <mn>2.9</mn> <mo>,</mo> <mn>4</mn> <mo>)</mo> </mrow> </semantics> </math>: (<b>a,b</b>) <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>y</mi> </mrow> </semantics> </math>; (<b>c,d</b>) <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics> </math>; (<b>e,f</b>) <math display="inline"> <semantics> <mrow> <mi>y</mi> <mo>−</mo> <mi>z</mi> </mrow> </semantics> </math>.</p>
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