一个分段Sprott系统及其混沌机理分析

提出了一个分段Sprott系统,对其混沌机理进行了分析.根据Shilnikov定理,在满足异宿轨道基本特性、Shilnikov不等式和特征方程条件下,通过寻找该系统中由不稳定流形、异宿点和稳定流形三个几何不变集上所形成的一条异宿轨道,在分段Sprott系统中导出了存在异宿轨道时该系统中各个参数应符合的条件, 并找到了一组对应的实参数,由此证明了异宿轨道的存在性.最后,根据这组对应的实参数,进行了电路设计与实验验证. 关键词： 分段Sprott系统 Shilnikov定理 异宿轨道 电路实验     

一个新四维自治超混沌系统及其电路实现

提出了一个新的四维超混沌系统,并对该系统的基本动力学特性进行了深入研究,得到该系统的LE,LE维数,给出了Poincare映射图、LE谱、分岔图以及时域图和相图.利用Mutisim软件设计了该新混沌系统的振荡电路并进行了仿真实验.经过数值仿真和电路系统仿真证实该系统与以往发现的混沌吸引子并不拓扑等价,属于新的混沌系统. 关键词： 超混沌系统 Lyapunov指数 Poincare截面图 电路实现     

一种超混沌映射的单双参量自适应同步

利用参量自适应法实现了超混沌系统Kawakami映射的同步.通过严密的数学推导,给出了Kawakami映射在单参量自适应下实现同步的充分条件,并在双参量自适应控制下系统同样实现了同步.数值模拟结果显示,该映射输出具有类似于白噪声的宽谱特性,因此比较适合用于保密通信.     

不同结构混沌系统的自适应同步和反同步

针对不同结构混沌系统的同步与反同步问题进行了研究.在系统参数已知时,采用主动控制法实现混沌系统的同步与反同步,并将主动控制器的设计方法进行了推广.在参数未知时,基于Lyapunov稳定性理论和自适应控制方法,给出了自适应控制器和参数自适应律,实现了参数均未知且结构不同的驱动系统和响应系统的同步与反同步.在控制器的设计过程中,将驱动系统和响应系统进行互换,讨论了互换前后的控制器和自适应律之间的关系.数值仿真结果说明了所提出设计方法的有效性. 关键词： 混沌同步 反同步 主动控制法 自适应控制法     

随机性参数自适应的混沌同步

对两个不同参数的混沌系统进行随机性参数自适应控制，选取合适的控制律和反馈系数，导致其同步.以Henon映射为例进行数值模拟，结果表明，由于控制周期和反馈系数的随机变化，具有一定的实用意义. 关键词： Henon映射 混沌同步 随机性自适应控制     

多涡卷混沌系统的广义同步控制

基于反步自适应方法,提出了一种在初值不同以及驱动系统参数未知的情况下,保持驱动和响应两多涡卷混沌系统同步的控制律设计方法.该方法所设计的控制律能够同时适用于两混沌系统的完全同步、反同步和一类非线性广义同步,具有较高的实用价值.仿真结果表明了所设计控制律的有效性. 关键词： 多涡卷混沌 广义同步 反步 自适应     

新三维混沌系统及其电路仿真

提出了一个新的不同于Lorenz系统和Chen系统的三维连续自治混沌系统.该系统含有五个参数,其中两个方程中各含有一个非线性乘积项.通过理论推导、数值仿真、Lyapunov指数谱、分岔图、Lyapunov维数、Poincare截面图研究了系统的基本动力学特性,并分析了改变不同参数时系统动力学行为的变化.最后设计了硬件电路并运用电子工作平台Multisim软件对该电路进行仿真实验,证实了该混沌系统的可实现性. 关键词： 混沌系统 Lyapunov指数 Poincare截面图 电路仿真     

自适应同步参数未知的异结构分数阶超混沌系统

基于分数阶系统稳定理论,实现了分数阶超混沌CYQY系统与参数未知的分数阶超混沌Lorenz系统间的异结构自适应同步.不仅设计了控制器,还设计了参数自适应规则并保留了非线性项.数值仿真证实了自适应控制器的有效性. 关键词： 分数阶 超混沌 同步 自适应     

直驱型永磁同步风力发电机组中混沌运动的反步自适应控制

以直驱型永磁同步风力发电机为研究对象, 推导了发电机在参数不确定以及风速扰动情况下的数学模型,验证了系统在某些参数及工作条件下会呈现出混沌属性. 并提出了直驱型永磁同步风力发电机混沌运动下的基于反步自适应控制算法,并对其进行了仿真, 仿真结果表明,所提出的算法对于具有参数不确定以及风速干扰的直驱型风力发电系统具有较好的鲁棒性. 关键词： 风力发电 直驱型永磁同步风力发电机组 混沌控制 反步自适应控制     

参数未知的统一超混沌系统自适应反同步

文章研究了参数未知的统一超混沌系统的控制与同步问题.首先基于Lyapunov稳定性理论,设计了自适应控制器,证明了该控制器可使参数未知统一超混沌系统渐近稳定于不动点.其次使用自适应反同步方法,设计了自适应同步控制器,实现了参数未知统一超混沌系统的完全同步,最后数值仿真实验进一步验证了所提出方案的有效性. 关键词： 统一超混沌系统 自适应控制器 自适应反同步     

A Numerical Study of Arnold Diffusion in a Priori Unstable Systems

This paper concerns the problem of the numerical detection of Arnold diffusion in a priori unstable systems. Specifically, we introduce a new definition of Arnold diffusion which is adapted to the numerical investigation of the problem, and is based on the numerical computation of the stable and unstable manifolds of the system. Examples of this Arnold diffusion are provided in a model system. In this model, we also find that Arnold diffusion behaves as an approximate Markovian process, thus it becomes possible to compute diffusion coefficients. The values of the diffusion coefficients satisfy the scaling . We also find that this law is correlated to the validity of the Melnikov approximation: in fact, the law is valid up to the same critical value of ε for which the error terms of Melnikov approximations have a sharp increment.     

Finite-size scaling and the renormalization group

Renormalization group calculations ind = 4 andd = 4 – are performed for a system of finite size. A form of mean-field theory is used which yields a rounded transition for a finite system, and this allows a sensible expansion in fluctuations. A combination of Ewald and Poisson sum techniques is used to produce explicit numerical results for the specific heat ind = 4 which, with the setting of two nonuniversal metrical factors and the fourth-order coupling constant may be compared with simulations. The numerical visibility of logarithmic corrections is investigated. The universal scaling function for the specific heat to relativeO() is also evaluated numerically.     

Ground state of the parallel double quantum dot system

We resolve the controversy regarding the ground state of the parallel double quantum dot system near half filling. The numerical renormalization group predicts an underscreened Kondo state with residual spin-1/2 magnetic moment, ln2 residual impurity entropy, and unitary conductance, while the Bethe ansatz solution predicts a fully screened impurity, regular Fermi-liquid ground state, and zero conductance. We calculate the impurity entropy of the system as a function of the temperature using the hybridization-expansion continuous-time quantum Monte Carlo technique, which is a numerically exact stochastic method, and find excellent agreement with the numerical renormalization group results. We show that the origin of the unconventional behavior in this model is the odd-symmetry "dark state" on the dots.     

LWDG Method for a Multi-Class Traffic Flow Model on an Inhomogeneous Highway

In this paper, we apply the discontinuous Galerkin method with Lax-Wendroff type time discretizations (LWDG) using the weighted essentially non-oscillatory (WENO) limiter to solve a multi-class traffic flow model for an inhomogeneous highway, which is a kind of hyperbolic conservation law with spatially varying fluxes. The numerical scheme is based on a modified equivalent system which is written as a "standard" hyperbolic conservation form. Numerical experiments for both the Riemann problem and the traffic signal control problem are presented to show the effectiveness of these methods.     

The Gravitating Perfect Fluid-Scalar Field Equations: Quintessence and Tachyonic Matter

The system consisting of a self gravitating perfect fluid and scalar field is considered in detail. The scalar fields considered are the quintessence and tachyonic forms which have important application in cosmology. Mathematical properties of the general system of equations are studied including the algebraic and differential identities as well as the eigenvalue structure. The Cauchy problem for both quintessence and the tachyon is presented. We discuss the initial constraint equations which must be satisfied by the initial data. A Cauchy evolution scheme is presented in the form of a Taylor series about the Cauchy surface. Finally, a simple numerical example is provided to illustrate this scheme.     

Bounds on the trajectories of a system of weakly coupled rotators

In this paper we study a classical mechanical system of weakly coupled rotators on a one-dimensional lattice. Such systems are of interest in statistical mechanics. We prove that for any site in the system there is a large set of initial conditions for which there exists a canonical change of variables such that the trajectory of that site, in the transformed system, is essentially indistinguishable from that of an integrable system for a long (but finite) time. Alternatively, the trajectory of this site lies very close to a torus in the phase space of the system for times very long in comparison with the typical period of the unperturbed rotators. All the estimates in this theory areindependent of the number of degrees of freedom in the system. We propose this mechanism as an explanation of certain numerical experiments.Supported in part by NSF Grant DMS-8403664     

Coexisting multiscroll hyperchaotic attractors generated from a novel memristive jerk system

In this paper, two kinds of novel non-ideal voltage-controlled multi-piecewise cubic nonlinearity memristors and their mathematical models are presented. By adding the memristor to the circuit of a three-dimensional jerk system, a novel memristive multiscroll hyperchaotic jerk system is established without introducing any other ordinary nonlinear functions, from which \(2N+2\)-scroll and \(2M+1\)-scroll hyperchaotic attractors are achieved. It is exciting to note that this new memristive system can produce the extreme multistability phenomenon of coexisting infinitely multiple attractors. Furthermore, the dynamical behaviours of the proposed system are analysed by phase portraits, equilibrium points, Lyapunov exponents and bifurcation diagrams. The results indicate that the system exhibits hyperchaotic, chaotic and periodic dynamics. Especially, the phenomenon of transient chaos can also be found in this memristive multiscroll system. Additionally, the MULTISIM circuit simulations and the hardware experimental results are performed to verify numerical simulations.     

光谱幅度编码OCDMA系统研究

针对单极性码在光码分多址系统应用中存在正交性和用户容纳能力较差的缺点，对采用双极性地址码的光谱幅度编码系统中接收端采用差分检测的方案进行了研究。讨论了用于差分频谱幅度编码方案中的地址码应满足的条件，对OOK和双极性编码系统方案，在考虑散弹噪声和热噪声的条件下，分析了误码率性能。通过数值计算，比较了“1”和“0”都发信号的系统和只有“1”发信号的系统性能。比较结果表明，双极性地址码方案可提高系统性能；另外，提高光功率还可改善系统性能。     

The transition from conservative to dissipative flows in class-B laser model with fold-Hopf bifurcation and coexisting attractors

Dynamical behaviors of a class-B laser system with dissipative strength are analyzed for a model in which the polarization is adiabatically eliminated. The results show that the injected signal has an important effect on the dynamical behaviors of the system. When the injected signal is zero, the dissipative term of the class-B laser system is balanced with external interference, and the quasi-periodic flows with conservative phase volume appear. And when the injected signal is not zero, the stable state in the system is broken, and the attractors (period, quasi-period, and chaos) with contractive phase volume are generated. The numerical simulation finds that the system has not only one attractor, but also coexisting phenomena (period and period, period and quasi-period) in special cases. When the injected signal passes the critical value, the class-B laser system has a fold-Hopf bifurcation and exists torus "blow-up" phenomenon, which will be proved by theoretical analysis and numerical simulation.     

Quantum Lyapunov Exponents

We show that it is possible to associate univocally with each given solution of the time-dependent Schrödinger equation a particular phase flow (quantum flow) of a non-autonomous dynamical system. This fact allows us to introduce a definition of chaos in quantum dynamics (quantum chaos), which is based on the classical theory of chaos in dynamical systems. In such a way we can introduce quantities which may be appelled quantum Lyapunov exponents. Our approach applies to a non-relativistic quantum-mechanical system of n charged particles; in the present work numerical calculations are performed only for the hydrogen atom. In the computation of the trajectories we first neglect the spin contribution to chaos, then we consider the spin effects in quantum chaos. We show how the quantum Lyapunov exponents can be evaluated and give several numerical results which describe some properties found in the present approach. Although the system is very simple and the classical counterpart is regular, the most non-stationary solutions of the corresponding Schrödinger equation are chaotic according to our definition.