基于等概率符号分析方法计算互信息确定延迟时间

用互信息函数确定混沌时间序列相空间重构最佳延迟时间.针对常规符号分析方法计算互信息准确度不高的缺陷,提出等概率符号分析方法计算互信息,即对时间序列按值域大小重排列,再对重排后的序列进行等概率分割,分割的组数由分组经验公式确定,然后取每组的边界值组成符号分析方法的临界点集合进行计算.通过对Lorenz方程和强迫Brusselator振子进行仿真实验,得到的最佳延时与Fraser等概率分格子法得到的结果一致,而算法上更容易实现,证明方法有效.     

相空间重构中延迟时间选取的新算法

根据Takens提出的嵌入理论,对比研究在相空间重构过程中对延迟时间选取的若干方法,提出一种新的平均位移-互信息联合算法.在互信息函数的具体计算上,引入二叉树的方法划分和标记网格,克服了以往算法繁琐、难以编程实现的缺点,并通过判断稀疏网格所占比例控制划分层数,获得较高的精度.最后通过对R ssler系统和Lorenz系统的数值仿真,证明算法具备更高的可行性与准确度.     

基于符号分析的极大联合熵延迟时间求取方法

本文通过符号分析法求取联合熵的极大值点, 进而得到相空间重构的最佳延迟时间, 通过对几个典型的混沌系统进行数值仿真试验, 结果表明, 该方法简化了计算, 提高了效率, 能够准确快速地获得最佳延迟时间, 从而有效地重构原系统的相空间, 为混沌信号识别提供一种快速有效的途径. 关键词： 相空间重构 延迟时间 联合熵 符号分析     

DC-DC变换器的符号时间序列描述及模块熵分析

本文提出了一种采用符号时间序列和熵理论分析DC-DC变换器非线性行为的方法.该方法首先用离散时间序列描述非线性连续系统,然后将其转换为由简单字符构成的符号序列,再用信息学方法计算出该符号序列的模块熵,从而得到一种新的可量化的非线性动力学行为统计指标.文中以一阶电压反馈DCM和二阶电流反馈CCM Boost变换器为例进行研究.研究结果表明,模块熵这种粗粒化的统计分析方法,能够量化DC-DC变换器的倍周期分岔和混沌行为,且能够准确地确定混沌行为的发生,是一种尚未在DC-DC变换器中提出的简单、实用的分析方法. 关键词： 符号时间序列 符号动力学 模块熵 Lyapunov指数     

On the Distribution of Long-Term Time Averages on Symbolic Space

The pressure was studied in a rather abstract theory as an important notion of the thermodynamic formalism. The present paper gives a more concrete account in the case of symbolic spaces, including subshifts of finite type. We relate the pressure of an interaction function to its long-term time averages through the Hausdorff and packing dimensions of the subsets on which has prescribed long-term time-average values. Functions with values in ^d are considered. For those depending only on finitely many symbols, we get complete results, unifying and completing many partial results.     

Influence of Dark Energy on Gravitational Time Delay

We investigate the gravitational time delay of light in the Schwarzschild black hole space-time surrounded by quintessence. With the analysis and numerical methods, we find that the gravitational time delay of light in the Schwarzschild black hole space-time surrounded by quintessence increases when the normalization factor c increases, and that the gravitational time delay also decreases when the quintessential state parameter ωq increases.     

Formative Time Delay in Nitrogen Discharges at Low Pressure

In this paper the formative time delay in nitrogen was determined from statistically based measurements of electrical breakdown time delay. The measurements were carried out under different conditions on a newlydesigned gas tube with a plane‐parallel electrode system made from copper. The avalanche growth was followed based on a simple analytical model agreeing well with the experimental data. The dependencies of the formative time delay on the working voltage and the electron yields in the interelectrode space originating from residual states were found. A developed approximate model for the formative time delay has shown fits with the experimental data better than other models discussed in the literature. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of Dark Energy on Gravitational Time Delay

We investigate the gravitational time delay of light in the Schwarzschild black hole space-time surrounded by quintessence. With the analysis and numerical methods, we find that the gravitational time delay of light in the Schwarzschild black hole space-time surrounded by quintessence increases when the normalization factor c increases, and that the gravitational time delay also decreases when the quintessential state parameter ω_q increases.     

Investigation of the Influence of Overvoltage,Auxiliary Glow Current and Relaxation Time on the Electrical Breakdown Time Delay Distributions in Neon

Results of the statistical analysis of the electrical breakdown time delay for neon‐filled tube at 13.3 mbar are presented in this paper. Experimental distributions of the breakdown time delay were established on the basis of 200 successive and independent measurements, for different overvoltages, relaxation times and auxiliary glows. Obtained experimental distributions deviate from usual exponential distribution. Breakdown time delay distributions are numerically generated, usingMonte‐Carlo method, as the compositions of the two independent random variables with an exponential and a Gaussian distribution. Theoretical breakdown time delay distribution is obtained from the convolution of the exponential and Gaussian distribution. Performed analysis shows that the crucial parameter that determines the complex structure of time delay is the overvoltage and if it is of the order of few percentage, then distribution of time delay must be treated as an convolution of two random variables. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Control Strategy of True Time Delay Lines

This article presents the control of adjustable true time delays applied to an optical beamforming system. First is introduced the response of ring resonators of two and four ports and the cascade and lattice structures. The coupling factor and the phase modulation are employed as the control parameters for the adjustable group delay. The strategy of control is proposed and applied to a cascade of five ring resonators for producing wideband true time delays in the picosecond–nanosecond range with 2-GHz bandwidth and extremely low ripple. Ripples lower than 0.1% were obtained for the adjusted group delays. The proposed strategy can be simply extended if more resonators are added to increase the bandwidth of the system.     

基于啁啾光纤光栅时分延时的相控阵波束形成

利用脉冲调制雷达信号的间歇性工作特点,不同波长的激光与雷达信号进行时分调制。啁啾光纤光栅将已调制射频信号的一串光脉冲序列进行反射延时,不同波长的激光序列在不同位置反射后产生不同时延。对载波频率等于4GHz的脉冲雷达信号进行实验测量,结果表明4个阵元的延时值与波束指向的理论延迟值一致,满足系统设计要求。     

JP-10点火延时的激波管研究

在预加热激波管上测定了JP-10的点火延时时间．采用高精度真空仪直接测定注入激波管中JP-10蒸气压力，获得了JP-10气相浓度，解决了高碳数碳氢燃料点火延时激波管实验时管壁吸附影响燃料气相浓度确定的困难．采用压力传感器、单色仪和光电倍增管记录得到了完整的点火过程引起的压力变化和OH或CH自由基发射强度变化．自由基发射信号作为诊断点火发生的手段．当实验压力为151?556 kPa，温度为1000?2120 K，JP-10摩尔百分比为0.1%?0.55%，化学当量比为0.25、0.5、1.0、2.0时，获得了点火延时时间与实验温度、JP-10浓度、O2浓度的依赖关系，结果还表明，高温区和低温区呈现出不同的依赖关系．     

啁啾光栅色散及时延特性研究

基于耦合模理论，通过对耦合波方程进行相位共轭变换，将反向耦合波方程变换为Ｒｉｃｃａｔｉ微分方程，利用数值解法对常耦合系数和高斯型耦合系数线性啁啾光栅的反射特性、色散特性和时延特性进行了详细分析，为设计具有理想效果的色散补偿器件提供了有效的理论方法。     

Position and Velocity Time Delay for Suppression Vibrations of a Hybrid Rayleigh-Van der Pol-Duffing Oscillator

In this paper, we used time delay feedback to minimize the vibrations of a hybrid Rayleigh–van der Pol–Duffing oscillator. This system is a one-degree-offreedom containing the cubic and fifth nonlinear terms and an external force. We applied the multiple scales method to get the solution from first approximation. Graphically and numerically, we studied the system before and after adding time delay feedback at the primary resonance case (Ω ≌ ω). We used MATLAB program to simulate the efficacy of different parameters and the time delay on the main system.     

非线性光导开关输出脉冲延迟时间的研究

利用非线性光导开关的雪崩注入模型，讨论了光导开关工作偏压、光导开关材料的深能级杂质浓度、光脉冲能量等参量对非线性光导开关输出脉冲延迟时间的影响，给出了一些有意义的结论。     

Evaluating Temporal Correlations in Time Series Using Permutation Entropy,Ordinal Probabilities and Machine Learning

Time series analysis comprises a wide repertoire of methods for extracting information from data sets. Despite great advances in time series analysis, identifying and quantifying the strength of nonlinear temporal correlations remain a challenge. We have recently proposed a new method based on training a machine learning algorithm to predict the temporal correlation parameter, α, of flicker noise (FN) time series. The algorithm is trained using as input features the probabilities of ordinal patterns computed from FN time series, xαFN(t), generated with different values of α. Then, the ordinal probabilities computed from the time series of interest, x(t), are used as input features to the trained algorithm and that returns a value, αe, that contains meaningful information about the temporal correlations present in x(t). We have also shown that the difference, Ω, of the permutation entropy (PE) of the time series of interest, x(t), and the PE of a FN time series generated with α=αe, xαeFN(t), allows the identification of the underlying determinism in x(t). Here, we apply our methodology to different datasets and analyze how αe and Ω correlate with well-known quantifiers of chaos and complexity. We also discuss the limitations for identifying determinism in highly chaotic time series and in periodic time series contaminated by noise. The open source algorithm is available on Github.     

TDLAS中激光器IM/FM相位延迟实时测量方法研究

在基于谐波检测法的TDLAS（可调谐二极管激光吸收光谱)系统中,在通过改变激光器注入电流实现激光频率扫描和调制的同时引起激光强度的变化,激光器输出信号的强度-频率(IM/FM)相位延迟_m的变化将直接导致谐波系数波动,带来系统误差。提出一种利用光纤迈克尔逊干涉仪实现激光器输出信号强度-频率(IM/FM)相位延迟_m的测量方法,能在激光器调制测量的同时实时测量相位延迟_m。实验结果表明,激光器输出信号强度-频率(IM/FM)相位延迟_m与理论值π有一定差异。研究提出的方法可以用来实时补偿信号强度-频率(IM/FM)相位延迟_m对气体浓度测量结果的影响。     

Time Delay Induced Stochastic Resonance in One Species Competition Ecosystem without a Periodic Signal

One-species competition ecosystem with noise and time delay was investigated as not driven by a periodic force.The results show that the time delay is responsible for stochastic resonance of the system as delay time is smaller than critical point of the Hopf bifurcation.     

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 τ₀, the intensities D and α 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.     

Analyses of Optimal Embedding Dimension and Delay for Local Linear Prediction Model

In the reconstructed phase space, a novel local linear prediction model is proposed to predict chaotic time series. The parameters of the proposed model take the values that are different from those of the phase space reconstruction. We propose a criterion based on prediction error to determine the optimal parameters of the proposed model. The simulation results show that the proposed model can effectively make one-step and multistep prediction for chaotic time series, and the one-step and multi-step prediction accuracy of the proposed model is superior to that of the traditional local linear prediction.