Transient Properties of a Bistable System with Delay Time Driven by Non-Gaussian and Gaussian Noises： Mean First-Passage Time

The mean first-passage time of a bistable system with time-delayed feedback driven by multiplicative non-Gaussian noise and additive Gaussian white noise is investigated. Firstly, the non-Markov process is reduced to the Markov process through a path-integral approach; Secondly, the approximate Fokker-Planck equation is obtained by applying the unified coloured noise approximation, the small time delay approximation and the Novikov Theorem. The functional analysis and simplification are employed to obtain the approximate expressions of MFPT. The effects of non-Gaussian parameter （measures deviation from Gaussian character） r, the delay time τ, the noise correlation time to, the intensities D and a of noise on the MFPT are discussed. It is found that the escape time could be reduced by increasing the delay time τ, the noise correlation time τ0, or by reducing the intensities D and α. As far as we know, this is the first time to consider the effect of delay time on the mean first-passage time in the stochastic dynamical system.     

Experimental investigation of slow light propagation in degenerate two-level system

Slowing a light pulse in a degenerate two-level system is observed with a double-frequency sweeping technique. The effects of coupling beam intensity, cell temperature and frequency detunings of the coupling and probe beams in resonance, on the slowing of light propagation in such a system are investigated. It is found that group velocities depend strongly on polarization combinations. A group velocity $v_{\rm g}$=6760m/s of light pulses in caesium vapour is obtained under the optimal parameters.     

各向同性坐标系中的雷达回波时间延迟

本文在静球对称Schwarzschild度规的各向同性坐标形式下,重新计算了雷达回波时间延迟,发现所得理论结果与标准坐标形式下的结果不同,并分析了它的内在原因。     

利用相空间重构时间延迟特性进行语音音质分析

在简要分析相空间重构时间延迟计算方法的基础上,利用复自相关时间延迟计算方法进行了语音信号相空间重构时间延迟的计算分析,通过对比不同信噪比下复自相关-时间延迟曲线,提出了利用时间延迟参数进行语音音质评估的方法,利用BP网络对大量试验数据进行建模,通过统计分析认为该方法具有一定的可行性。     

Stochastic Resonance in a Time-Delayed Bistable System Driven by Square-Wave Signal

Stochastic resonance in a time-delayed bistable system subject to asymmetric dichotomous noise and multiplicarive and additive white noise is investigated. Using small time delay approximation, we obtain the expression of the signal-to-noise ratio （SNR）. It is found that the SNR is a non-monotonic function of the delayed times, of the amplitude of the input square-wave signal, as well as of the asymmetry of the dichotomous noise. In addition, the SNR varies non-monotonously with the system parameters, with the intensities of the multiplicative and additive noise, as well as with the correlate rate of the dichotomous noise.     

时间延迟增强双稳系统的共振抑制

研究了时间延迟对双稳系统激活率的影响.在短时间延迟的情况下,应用最陡下降法导出延迟双稳系统的平均首通时间表达式和相应的与延迟时间有关的激活率表达式.数值计算结果表明,时间延迟可以增强双稳系统的共振抑制.     

时间延迟增强双稳系统的共振抑制

研究了时间延迟对双稳系统激活率的影响.在短时间延迟的情况下,应用最陡下降法导出延迟双稳系统的平均首通时间表达式和相应的与延迟时间有关的激活率表达式.数值计算结果表明,时间延迟可以增强双稳系统的共振抑制.     

Generalized Synchronization of Time-Delayed Discrete Systems

This paper establishes two theorems for two time-delayed （chaotic） discrete systems to achieve timedelayed generalized synchronization （TDGS）. These two theorems uncover the genera/forms of two TDGS systems via a prescribed transformation. As examples, we convert the Lorenz three-dimensional chaotic map to an equal time-delayed system as the driving system, and construct the TDGS driven systems according to the Theorems 1 and 2. Numerical simulations demonstrate the effectiveness of the proposed theorems.     

Increasing-order Projective Synchronization of Chaotic Systems with Time Delay

This work is concerned with lag projective synchronization of chaotic systems with increasing order. The systems under consideration have unknown parameters and different structures. Combining the adaptive control method and feedback control technique, we design a suitable controller and parameter update law to achieve lag synchronization of chaotic systems with increasing order. The result is rigorously proved by the Lyapunov stability theorem. Moreover, corresponding simulation results are given to verify the effectiveness of the proposed methods.