控制单模激光Haken-Lorenz系统混沌的一种有效方法

基于变量脉冲反馈法(VPF)的设计思想,提出了一种控制非线性系统中混沌的新方法——变量变化率脉冲反馈(VRPF)法.将此方法应用到单模激光Haken-Lorenz系统混沌的控制中,计算机模拟结果表明,通过恰当地选择反馈系数和脉冲间隔,可以将系统稳定在1p、2p、3p…2mp、3np以及2mp×3np这样不同的周期轨道,并且获得同一周期轨道的反馈系数和脉冲间隔并不是唯一的.     

非线性光学 非线性光学器件

O437 2005010226 控制单模激光Haken-Lorenz系统混沌的一种有效方法= A valid method of controlling chaos in single-mode laser Haken-Lorenz system[刊,中]／吕翎(辽宁师范大学物理系．辽宁,大连(116029)),栾玲…∥光子学报．-2004,33 (4)．-416-419 基于变量脉冲反馈法(VPF)的设计思想,提出了一种控制非线性系统中混沌的新方法-变量变化率脉冲反馈 (VRPF)法。将此方法应用到单模激光Heken-Lorenz系统混沌的控制中,计算机模拟结果表明,通过恰当地选择     

PO反应中混沌控制的变量交叉反馈方法研究

设计了一种变量交叉反馈(VCF)方法控制非线性系统混沌.介绍了VCF方法的控制原理,并用此方法 控制Peroxidase Oxidase(PO)反应系统的混沌,以此验证其有效性.仿真模拟显示,通过恰当地选择控制系数m1、 m2,可以使受控系统的返回映像由具有一定分布形式和结构的离散点的集合转变为有限个点,功率谱也由连续 谱转变为具有独立单峰的分立谱,从而使以[O2]和[NADH]的浓度作为反馈变量的受控系统的动力学性质由混 沌态转变为周期态,周期态轨道的周期数为2n×3mp(n,m为整数).     

状态反馈控制声光双稳系统的倍周期分岔和混沌

设计了一种动力学状态反馈(DSF)方法控制非线性混沌系统.介绍了DSF方法的控制原理,并用此方法控制声光双稳(AOB)系统的混沌,以此验证其有效性.仿真模拟显示,通过选择恰当的控制参数,有效地实现了声光双稳(AOB)系统中倍周期分岔的延迟控制和混沌吸引子中原不稳定周期轨道的稳定控制,同时,还可以将系统控制在2np、3mp 和2np×3mp这样其它任意所需的周期轨道上.     

混沌系统的递次错位反馈控制方法研究

设计了一种递次错位反馈控制（SDF）方法来实现混沌控制.介绍了SDF方法的控制原理,以单模激光Lorenz混沌系统作为典型的例子,验证了这种控制方法的有效性.比较单模激光Lorenz混沌系统受控前后相图、功率谱和相空间重构等刻划混沌系统的特征量.数值模拟结果显示, 受控系统的相图和相空间重构中由具有无穷嵌套自相似结构并限定在有限相空间内的混沌吸引子转变为周期数为2ⁿ×3^mp(n、m为整数)的周期轨道;同时,功率谱也由连续谱转变为具有独立单峰的分立谱.     

电磁场中空间思维的构建

利用电子线路实验实现了用变量脉冲扰动法控制离散混沌 .该方法只用单一输出信号作为反馈信号 ,每隔一定的脉冲间隔将其加到系统的某些变量中去 ,适当调节脉冲间隔和反馈系数 ,可得到多个稳定的周期轨道 .该方法不仅适用于一维和二维离散系统 ,也适用于三维或更高维的离散系统 .     

非线性反馈控制单模激光Haken-Lorenz混沌系统

提出一种变量非线性反馈（VNF）方法控制混沌系统.介绍了该方法的控制原理以及反馈系数的选取原则,以单模激光Haken-Lorenz系统为例对非线性反馈控制方法进行了理论研究.仿真结果显示,通过恰当的选择反馈系数k,使系统的最大李雅普诺夫（Lyapunov）指数由正值转变为负值,相图中系统的轨迹由混沌吸引子转变为周期数为2n×3mp(n、m为整数)的周期轨道.通过与线性反馈控制结果对比发现,非线性反馈控制方法简便有效,控制速度快.     

光电反馈混沌系统脉冲同步特性研究

提出光电反馈混沌状态下的混沌脉冲同步.首先, 对激光器的混沌动力学方程进行了数值分析, 通过改变反馈系数和脉冲系数来观测混沌状态的变化, 实现了对混沌激光器的控制;然后, 对脉冲同步方程进行数值分析, 给出了同步的模拟图.实验结果表明此方法能实现混沌同步.     

变量脉冲扰动法控制离散混沌系统的实验

利用电子线路实验实现了用变量脉冲扰动法控制离散混沌．该方法只用单一输出信号作为反馈信号，每隔一定的脉冲间隔将其加到系统的某些变量中去，适当调节脉冲间隔和反馈系数，可得到多个稳定的周期轨道．该方法不仅适用于一维和二维离散系统，也适用于三维或更高维的离散系统．     

用系统变量比例脉冲方法控制超混沌的电路实验研究

利用电子线路实验实现了用正比于系统变量周期脉冲扰动法(PP-SV)控制超混沌,只用单一输出信号作为反馈信号,改变原来只对系统变量进行自身替换的方式,将反馈信号加到系统的其他变量上.将这种改进的方式用于一个超混沌电路中,得到了很好的控制效果.数值模拟结果与实验结果基本符合. 关键词： 超混沌 电路实验 脉冲扰动 反馈控制     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

High efficiency filtering using two-dimensional photonic crystal coupled cavity structures

Transmission spectra of coupled cavity structures (CCSs) in two-dimensional (2D) photonic crystals (PCs) are investigated using a coupled mode theory, and an optical filter based on CCS is proposed. The performance of the filter is investigated using finite-difference time-domain (FDTD) method, and the results show that within a very short coupling distance of about 3λ, where λ is the wavelength of signal in vacuum, the incident signals with different frequencies are separated into different channels with a contrast ratio of 20 dB. The advantages of this kind of filter are small size and easily tunable operation frequencies.     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.     

Real-time restoration of rotational blurred image using gradient-loading

The key to the restoration of rotational motion blurred image is how to restore the image under a low cost and to correct the irreversibility of the degradation function matrix.Based on the special qualities of degradation function matrix and precise deduction in space-domain, we present a new approach using gradient-loading for restoration of rotational blurred image.By easily adding a gradient operator, the irreversibility of the original matrix is corrected and can be applied for inverse filtering then.Gradientloading is the optimized approach which combines the advantages of both the approaches using constrained least square filtering and traditional diagonal-loading.Compared with the approach using least square filtering, its peak signal-to-noise ratio (PSNR) is improved from 3.18 to 6.46dB, while the computing time is reduced to 1/2-1/3.Experimental results demonstrate the effectiveness, noise-resistibility, robustness, and low complexity of this approach, which make it more suitable for real-time environment.     

All-Optical Logic Device Using Bent Nonlinear Tapered Y-Junction Waveguide Structure

We propose an all-optical logic device made of a bent tapered Y-junction waveguide with a Kerr-type nonlinear interface. It could provide an AND gate, OR gate, and exclusive-OR (XOR) gate. We could obtain different transmission results by adjusting the bending angle. The numerical simulation results show that the device functions as AND, OR, and XOR gates.     

Real-time, continuous-wave terahertz imaging by a pyroelectric camera

Real-time, continuous-wave terahertz (THz) imaging is demonstrated. A 1.89-THz optically-pumped farinfrared laser is used as the illumination source, and a 124 × 124 element room-temperature pyroelectric camera is adopted as the detector. With this setup, THz images through various wrapping materials are shown. The results show that this imaging system has the potential applications in real-time mail and security inspection.