共查询到20条相似文献,搜索用时 15 毫秒
1.
We investigate cluster formation in populations of coupled chaotic model neurons under homogeneous global coupling, and distance-dependent coupling, where the coupling weights between neurons depend on their relative distance. Three types of clusters emerge for global coupling: synchronized cluster, two state cluster and anti-phase cluster. In addition to these, we find a novel three state cluster for distance-dependent coupling, where the population splits into two synchronized groups and one incoherent group. Lastly, we study a system with random inhomogeneous coupling strengths, in order to discern if the special pattern found in distance-dependent coupling arises from the underlying lattice structure or from the inhomogeneity in coupling. 相似文献
2.
We analyze the critical transitions (a) to endemic states in an SIS epidemiological model, and (b) to full synchronization in an ensemble of coupled chaotic maps, on networks where, at any given time, each node is connected to just one neighbour. In these “monogamous” populations, the lack of connectivity in the instantaneous interaction pattern—that would prevent both the propagation of an infection and the collective entrainment into synchronization—is compensated by occasional random reconnections which recombine interacting couples by exchanging their partners. The transitions to endemic states and to synchronization are recovered if the recombination rate is sufficiently large, thus giving rise to a bifurcation as this rate varies. We study this new critical phenomenon both analytically and numerically. 相似文献
3.
Complex adaptive systems have been the subject of much recent attention. It is by now well established that members ("agents") tend to self-segregate into opposing groups characterized by extreme behavior. However, the study of such adaptive systems has mostly been restricted to simple situations in which the prize-to-fine ratio R equals unity. In this Letter we explore the dynamics of evolving populations with various different values of the ratio R, and demonstrate that extreme behavior is in fact not a generic feature of adaptive systems. In particular, we show that "confusion" and "indecisiveness" take over in times of depression, in which case cautious agents perform better than extreme ones. 相似文献
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We consider the collective dynamics in an ensemble of globally coupled chaotic maps. The transition to the coherent state with a macroscopic mean field is analyzed in the framework of the linear response theory. The linear response function for the chaotic system is obtained using the perturbation approach to the Frobenius-Perron operator. The transition point is defined from this function by virtue of the self-excitation condition for the feedback loop. Analytical results for the coupled Bernoulli maps are confirmed by the numerics. 相似文献
6.
We study a family of equivalent continuum models in one dimension. All these models map onto a single equation and include
simple chemical reactions, diffusion in presence of a trap or a source and an ideal polymer chain near an attractive or repulsive
site. We have obtained analytical results for the survival probability, total growth rate, statistical properties of nearest-neighbour
distribution between a trap and unreacted particle and mean-squared displacement of the polymer chain. Our results are compared
with the known asymptotic results in the theory of discrete random walks on a lattice in presence of a defect. 相似文献
7.
Synchronization of chaotic vertical-cavity surface-emitting lasers (VCSELs) is achieved by external chaotic signal modulation successfully. Simulation indicates that we can get chaos synchronization if the intensity of external chaotic signal is large enough. First of all, we use direct current modulation to achieve the chaos of VCSELs, and determine the laser's chaotic state by analyzing time series of the output and the corresponding power spectrum. And then we achieve synchronization of the two chaotic systems by external chaotic signal parameter modulation. We also find that the larger the modulation intensity is, the easier it is to achieve synchronization for chaotic VCSELs. This approach can also be applied to systems with a number of modulated lasers. 相似文献
8.
Synchronization between fractional-order chaotic systems and integer orders chaotic systems (fractional-order chaotic systems) 下载免费PDF全文
Based on the idea of tracking control and stability theory of fractional-order systems, a controller is designed to synchronize the fractional-order chaotic system with chaotic systems of integer orders, and synchronize the different fractional-order chaotic systems. The proposed synchronization approach in this paper shows that the synchronization between fractional-order chaotic systems and chaotic systems of integer orders can be achieved, and the synchronization between different fractional-order chaotic systems can also be realized. Numerical experiments show that the present method works very well. 相似文献
9.
《Physics letters. A》1999,251(3):169-176
We present a new chaotic masking scheme by using synchronized chaotic systems. In this method, synchronization and message transmission phases are separated, and while synchronization is achieved in the synchronization phases, the message is only sent in message transmission phases. We show that if synchronization is achieved exponentially fast, then under certain conditions any message of any length could be transmitted and successfully recovered provided that the synchronization length is sufficiently long. We also show that the proposed scheme is robust with respect to noise and parameter mismatch under some mild conditions. 相似文献
10.
Senlin Yan 《中国光学快报(英文版)》2005,3(5)
We present an all-optical chaotic multi-quantum-well (MQW) laser repeater system to be used in long-haul chaotic communications. Chaotic synchronization is achieved among transmitter, repeater, and receiver. Chaotic repeater communications with a sinusoidal signal of 0.2-GHz modulation frequency and a digital signal of 0.4-Gb/s bit rate are numerically simulated, respectively. Calculation results illustrate that the signals are well decoded by the chaotic repeaters. Its bandwidth and the characteristics at much high bit rate are also analyzed. Simulation shows that the repeater can improve decoding quality, especially in higher bit rate chaotic communications. 相似文献
11.
Chaotic systems perform well as a new rich source of
cryptography and pseudo-random coding. Unfortunately their digital
dynamical properties would degrade due to the finite computing
precision. Proposed in this paper is a modified digital chaotic
sequence generator based on chaotic logistic systems with a coupling
structure where one chaotic subsystem generates perturbation signals
to disturb the control parameter of the other one. The numerical
simulations show that the length of chaotic orbits, the output
distribution of chaotic system, and the security of chaotic
sequences have been greatly improved. Moreover the chaotic sequence
period can be extended at least by one order of magnitude longer
than that of the uncoupled logistic system and the difficulty in
decrypting increases 2128*2128 times indicating that the
dynamical degradation of digital chaos is effectively improved. A
field programmable gate array (FPGA) implementation of an algorithm
is given and the corresponding experiment shows that the output
speed of the generated chaotic sequences can reach 571.4~Mbps
indicating that the designed generator can be applied to the
real-time video image encryption. 相似文献
12.
提出混沌通信中继器设想,建立半导体激光器激光混沌全光中继器物理模型,理论证明了激光混沌中继器系统的同步.数值实现了发射系统、中继器系统、接收系统的混沌同步,分析了系统反馈系数和同步误差以及同步时间的关系.模拟了中继器系统在激光混沌保密通信中的应用,分别给出了具有正弦信号调制频率0.2GHz和数字信号0.2Gb/s速率的混沌通信以及同步误差分析,表明混沌中继器系统确能改善和提高激光混沌通信的解码质量.分析了中继器系统的带宽和20Gb/s高速率数字信号混沌通信以及同步误差,给出了具有正弦信号调制频率0.1—2
关键词:
混沌
同步
激光器
中继器 相似文献
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The distribution of tunneling rates in the presence of classical chaos is derived. We use classical information about tunneling trajectories plus random matrix theory arguments about wave function overlaps. The distribution depends on the stability of a specific tunneling orbit and is not universal, though it does reduce to the universal Porter-Thomas form when the orbit is very unstable. For some situations there may be systematic deviations due to scarring of real periodic orbits. The theory is tested in a model problem and possible experimental realizations are discussed. 相似文献
16.
Results of a detailed numerical study on the structure of chaotic bands in a forced limit cycle oscillator (the Brusselator) are presented. Embedded in the chaotic bands of primary bifurcation sequence there are many secondary sequences with both direct and inverse segments. Within secondary chaotic bands tertiary sequences of similar structure exist. This has been shown by using subharmonic stroboscopic sampling combined with power spectra analysis. 相似文献
17.
《Physics letters. A》2003,320(1):39-46
We have observed anti-synchronization phenomena in coupled identical chaotic oscillators. Anti-synchronization can be characterized by the vanishing of the sum of relevant variables. We have qualitatively analyzed its base mechanism by using the dynamics of the difference and the sum of the relevant variables in coupled chaotic oscillators. Near the threshold of the synchronization and anti-synchronization transition, we have obtained the novel characteristic relation. 相似文献
18.
In an experimental investigation of the response of a chaotic system to a chaotic driving force, we have observed synchronization of chaos of the response system in the forms of generalized synchronization, phase synchronization, and lag synchronization to the driving signal. In this paper we compare the features of these forms of synchronized chaos and study their relations and physical origins. We found that different forms of chaotic synchronization could be interpreted as different stages of nonlinear interaction between the coupled chaotic systems. (c) 1998 American Institute of Physics. 相似文献
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Starting from the semiclassical dynamical zeta function for chaotic Hamiltonian systems we use a combination of the cycle expansion method and a functional equation to obtain highly excited semiclassical eigenvalues. The power of this method is demonstrated for the anisotropic Kepler problem, a strongly chaotic system with good symbolic dynamics. An application of the transfer matrix approach of Bogomolny is presented leading to a significant reduction of the classical input and to comparable accuracy for the calculated eigenvalues. 相似文献
20.
《Physics letters. A》1986,115(9):433-436
We contrast analytic properties of chaotic maps with the results of fixed-precision computation and then use Turing's ideas of computable irrational numbers to illustrate the computation of chaotic orbits to arbitrary N-bit precision. This leads to the study of chaos theory via integer maps that are automata with long-range site interactions. We also explain why the β-shadowing lemma is not a justification for the use of fixed-precision arithmetic in chaos theory. 相似文献