四维超混沌系统及其在信号加密中的应用

为获得复杂的混沌信号源,构建四维超混沌系统,同时提出一种基于该系统的信号加密算法.构建系统模型,得到该系统的Lyapunov指数,给出了系统的相轨迹图,实现电路及该实现电路的相轨迹图;依据混沌隐藏技术,将该四维超混沌系统作为混沌加密通信的信号源,把待加密的信号与混沌信号相叠加,再把迭代次数与混沌信号的算术运算相结合作为密码设置,以实现信号加密.仿真结果表明,实现电路的相轨迹图与系统的相轨迹图完全一致,证实所构建的电路系统为超混沌系统,且该系统可以作为混沌加密通信的信号源实现对信号进行加密,为信息加密提供了一种新方法.     

Bifurcation and Hausdorff dimension in families of chaotically driven maps with multiplicative forcing

We study bifurcations of invariant graphs in skew-product dynamical systems driven by hyperbolic surface maps T like Anosov surface diffeomorphisms or baker maps and with one-dimensional concave fibre maps under multiplicative forcing when the forcing is scaled by a parameter r = e ^?t . For a range of parameters two invariant graphs (a trivial and a non-trivial one) coexist, and we use thermodynamic formalism to characterize the parameter dependence of the Hausdorff and packing dimension of the set of points where both graphs coincide. As a corollary we characterize the parameter dependence of the dimension of the global attractor : Hausdorff and packing dimension have a common value , and there is a critical parameter γ^? _c determined by the SRB measure of T ^?1 such that for t?γ^? _c and is strictly decreasing for t∈[γ^? _c , γ_max ).     

Life as we know it

This paper presents a heuristic proof (and simulations of a primordial soup) suggesting that life—or biological self-organization—is an inevitable and emergent property of any (ergodic) random dynamical system that possesses a Markov blanket. This conclusion is based on the following arguments: if the coupling among an ensemble of dynamical systems is mediated by short-range forces, then the states of remote systems must be conditionally independent. These independencies induce a Markov blanket that separates internal and external states in a statistical sense. The existence of a Markov blanket means that internal states will appear to minimize a free energy functional of the states of their Markov blanket. Crucially, this is the same quantity that is optimized in Bayesian inference. Therefore, the internal states (and their blanket) will appear to engage in active Bayesian inference. In other words, they will appear to model—and act on—their world to preserve their functional and structural integrity, leading to homoeostasis and a simple form of autopoiesis.     

基于混沌神经网络公钥算法的RFID协议

物联网的时代即将来临,国家"十二五"发展规划明确将物联网上升到国家战略高度。作为物联网关键技术的射频识别(RFID,Radio Frequency Identification)系统的安全问题变得越来越重要。通过分析多种RFID认证协议的优缺点,基于神经网络混沌吸引子公钥加密算法提出一种新的RFID认证协议,对该协议的安全性和性能同其他安全协议进行了比较分析,结果表明该协议可以为RFID系统提供更好的安全性和较快的加解密速度,且性能较佳。     

一个四翼吸引子的超混沌系统设计与实现

为提高混沌吸引子的拓扑结构的复杂性,利用把z轴双极性化的方法,通过修改已知系统的第3个方程,将原系统的双翼吸引子系统变为了四翼吸引子系统,对新产生的系统进行了理论分析和计算机仿真,Lyapunov指数计算表明系统具有两个正的Lyapunov指数,采用模块化的方法,设计了一个模拟电路对系统进行了实验,实验所得相图与数值仿真一致,二者都是具有四翼的吸引子,从而证明了理论分析和数值仿真的正确性。     

Feature Extraction Based on Speech Attractors in the Reconstructed Phase Space for Automatic Speech Recognition Systems

In this paper, a feature extraction (FE) method is proposed that is comparable to the traditional FE methods used in automatic speech recognition systems. Unlike the conventional spectral‐based FE methods, the proposed method evaluates the similarities between an embedded speech signal and a set of predefined speech attractor models in the reconstructed phase space (RPS) domain. In the first step, a set of Gaussian mixture models is trained to represent the speech attractors in the RPS. Next, for a new input speech frame, a posterior‐probability‐based feature vector is evaluated, which represents the similarity between the embedded frame and the learned speech attractors. We conduct experiments for a speech recognition task utilizing a toolkit based on hidden Markov models, over FARSDAT, a well‐known Persian speech corpus. Through the proposed FE method, we gain 3.11% absolute phoneme error rate improvement in comparison to the baseline system, which exploits the mel‐frequency cepstral coefficient FE method.     

一类抽象随机发展方程的随机吸引子

在可分希尔伯特空间H上研究了抽象随机发展方程dX_t=A(X_t)d t-v X_td t+σ X_tdN_t的长时间动力行为,其中算子A满足标准单调性条件和强迫性条件,σ>0, N_t是标准实值Wiener过程.利用近似逼近方法证明了上述方程的随机吸引子的存在性,此结果可应用于随机非线性反应扩散方程、随机p -拉普拉斯方程和随机多孔介质方程等各类型的SPDE上.     

复Ginzburg-Landau方程在权空间上的长时间行为

在整体解的存在性的基础上,考虑带高阶非线性项的复Ginzburg-Landau方程的解的长时间行为。通过引入权空间,应用内插不等式和先验估计,获得复Ginzburg—Landau方程整体弱吸引子的存在性。进一步使用在权空间算子分解的方法,通过构造紧的正向不变吸收集,建立了整体强吸引子的存在性。     

一个新四翼超混沌系统及其在图像加密中应用

提出了一个新的四翼超混沌系统,并将该系统应用于图像加密中。分析新系统的相图、平衡点、Lyapunov指数谱及分岔图等基本动力学特性,着重对系统参数变化引起的Lyapunov指数谱及分岔图详细分析,并设计该系统的模拟电路,电路实验结果与理论分析结果一致,验证了系统的超混沌行为。最后将此四翼超混沌系统应用于图像加密中,分析加密前后图像的直方图和相邻像素间相关性等,验证该系统应用于图像加密的效果良好。     

调参随机共振在超高频微弱信号检测中的应用

针对经典随机共振（SR）理论只适用于小参数,在提取高频微弱信号失效而无法使用的问题,提出一种调参随机共振检测高频率微弱信号的方法。首先,推导出双稳系统中阻尼系数与信号频率的关系,并以Kramers逃逸速率为分析手段,讨论阻尼系数变化对系统发生随机共振的影响;然后,分析了系统形状参数对系统产生随机共振现象的影响,通过联合调整阻尼系数和系统参数实现了大频率微弱信号的检测,并讨论了不同采样频率与调参系统输出频谱特性的影响,验证了该方法在低采样率下仍具有较强的稳定性;最后,以通用软件无线电设备（USRP）接收的无线电带噪信号作为系统的输入进行仿真。实验结果表明,利用该调参随机共振策略能够稳定有效地检测出强噪声背景下的超高频微弱信号,信号频率可达到MHz、GHz,拓展了随机共振原理的微弱信号检测的应用领域。