2,312 publications from this institution
In this paper, we consider the nonlinear dynamical behavior of a single neuron model with adapting feedback synapse, and show that chaotic behaviors exist in this model. In some parameter domain, we observe two coexisting chaotic attractors, switching from the coexisting chaotic attractors to a connected chaotic attractor, and then switching back to the two coexisting chaotic attractors. We confirm the chaoticity by simulations with phase plots, waveform plots, and power spectra.
Summary form only given, as follows. A complete record of the panel discussion was not made available for publication as part of the conference proceedings. The theme of the IEEE ICCA plenary session this year is Trends in Research on Multi-agent Systems. We are honored that four prominent researchers in our field will join this panel to share their expertise and visions, as well as to discuss about challenges and opportunities, in research on multi-agent systems. Through direct conversation between these world-renowned panelists and other ICCA attendees, we hope to gain a deeper insight into some fundamental and emerging problems in the research area of multi-agent systems and in our general field of control and automation. This panel will also serve as a platform for the audience, in particular students and other junior researchers, to hear the opinions of senior members of our community on issues we often face at the early stage of our career or study.
In this letter, we study the chaotic behaviors in the fractional order Chen system. We found that chaos exists in the fractional order Chen system with order less than 3. The lowest order we found to have chaos in this system is 2.1. Linear feedback control of chaos in this system is also studied.
The Lai-Chen algorithm, an extended feedback control scheme of the original Chen- Lai algorithm, was proposed to gradually make an arbitrarily given discrete-time dynamical system chaotic in terms of possessing positive Lyapunov exponents with uniformly bounded orbits. In this paper, based on the Monte Carlo method, we further study the distribution of the controlled Lyapunov exponents generated by the Lai-Chen algorithm.
Beam halo-chaos in high-current accelerators has become a key concerned issue because it can cause excessive radioactivity from the accelerators therefore significantly limits their applications in industry, medicine, and national defense. This article reviews the complexity of accelerator driven clean nuclear power system (ADS) as well as the associate physical mechanism for beam halo-chaos formation in high-intensity proton linear accelerator. Notably, some general engineering methods for chaos control have been developed in recent years, but they are generally unsuccessful for beam halo-chaos suppression due to many technical constraints. In this article, some of these technical problems are addressed. Particles-in-Cell (PIC) simulations are described, for exploring the nature of beam halo-chaos formation. Some efficient nonlinear control methods, including wavelet function feedback control, are reported for beam halo-chaos suppression. PIC simulations show that after control is applied to the initial proton beam with water bag or full Gauss distributions, the beam halo strength factor is quickly reduced to zero, and other statistical physical quantities of beam halo-chaos are also doubly reduced. These performed PIC simulation results demonstrate that the developed methods are very effective for halo-chaos suppression. Potential applications of the beam halo-chaos control methods are finally discussed.
This letter addresses the problem of robust adaptive control for synchronization of continuous-time coupled chaotic systems, which may be subjected to disturbances. A general model is studied via two different approaches, using either state feedback or measured output feedback controls. Adaptive controllers are designed, in which a sliding mode structure is employed to increase the robustness of the closed-loop systems. When only output variables are measurable for synchronization, the adaptive controllers are designed by incorporating with a filter and using the so-called σ-modification technique. Several numerical examples are presented to show the effectiveness of the proposed chaos synchronization methods.
Classification of homoclinic tangencies for periodically perturbed systems is discussed. A relationship between the order of Melnikov function’s zeros and the harmonic components of a dynamical system is derived. By applying the singularity theory to the Melnikov function, possible types of homoclinic tangencies are studied for realization of the classification. In addition, certain multi-harmonically perturbed systems are investigated, showing the corresponding homoclinic bifurcation with their bifurcation diagrams.
No abstract is provided for this article.
In this paper the problem of second-order consensus in multi-agent dynamical systems with sampled position data is addressed. Both the current and some sampled past position data are used to design a distributed linear consensus protocol with second-order dynamics. It turns out that sampled position data, especially the sampling period, is critical for such a multi-agent system to achieve second-order consensus under the given protocol. Then a necessary and sufficient condition for reaching consensus is derived, followed by a characterization of consensus regions. When the eigenvalues of the Laplacian matrix are all real-valued, the multi-agent system can achieve second-order consensus almost for any sampling period. The proposed theory is validated by computer simulations.
This paper is concerned with chaos of discrete dynamical systems in complete metric spaces. Discrete dynamical systems governed by continuous maps in general complete metric spaces are first discussed, and two criteria of chaos are then established. As a special case, two corresponding criteria of chaos for discrete dynamical systems in compact subsets of metric spaces are obtained. These results have extended and improved the existing relevant results of chaos in finite-dimensional Euclidean spaces.
A large number of real-world complex networks or their sub-networks possess excellent dynamical properties such as high dynamic synchronizability, optimal controllability, strong resistance to attacks, and fast information spreading capability, but existing network models are unable to well represent these intrinsic features and ubiquitous phenomena. This paper establishes an optimal homogeneous network model which can well describe at least one of such optimal dynamical behaviors - the best possible synchronizability.
To some, the answer can be a very quick "yes"; but to many, this question deserves consideration. Every day you receive tens of submissions on top of an already growing pile of manuscripts awaiting review assignments, so you start to panic. Worse is still ahead. All of a sudden, you receive an e-mail complaining that a paper has not been assigned for review after being submitted for so long, or that a paper has not been published after being accepted for so long. When this happens, you do not wish to be an editor.
Degenerate (or singular) Hopf bifurcations of a certain type determine the appearance of multiple limit cycles under system parameter perturbations. In the study of these degenerate Hopf bifurcations, computational formulas for the stability indexes (i.e., curvature coefficients) are essential. However, such formulas are very difficult to derive, and so are usually computed by different approximation methods. Inspired by the feedback control systems methodology and the harmonic balance approximation technique, higher-order approximate formulas for such curvature coefficients are derived in this paper in the frequency domain setting. The results obtained are then applied to a study of nonlinear dynamical systems within the region of one periodic solution, bypassing a direct investigation of the multiple limit cycles and some tedious discussion of the complex multiplicity issue. Finally, we will show that several types of stability bifurcations can be controlled based on the results obtained in this paper.
No abstract is provided for this article.
To further mitigate the BER error floor of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$M$</tex-math></inline-formula> -ary differential chaos shift keying (MDCSK) modulation for impulsive noise, a low-cost high-reliability coded modulation scheme without equalizations is desirable for impulsive noise. In this paper, a protograph-based low-density parity-check coded MDCSK-based bit-interleaved coded modulation (MDCSK-BICM) scheme is proposed for the scenario with impulsive noise obeying Bernoulli-Laplace distribution. Considering the Gaussian distribution of protograph extrinsic information transfer (PEXIT) and the benchmark of coding design, the U-shaped non-coherent capacity is derived with optimal code rate for square MDCSK, showing that the code rates are stable with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$E_b/N_0$</tex-math></inline-formula> increasing but still much lower than that of DS-16DQAM at code rate <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$>\!0.145$</tex-math></inline-formula> . The derived joint probability density function can be considered as approximately a Gaussian distribution, which is used to improve the impulsive noise fitted PEXIT. Finally, a new code under a novel principle is designed for better bit error rate performance based on the improved PEXIT analysis. Both PEXIT analysis and simulation results demonstrate that the proposed scheme achieves a better BER than that with a traditional scheme, and suggesting a research approach based on simple methods. This basic research work provides a guide to establish a framework and optimize the performance of transmission systems over practical power line communication.
