Phase Propagations in a Coupled Oscillator-Excitor System of FitzHugh-Nagumo Models

A one-dimensional array of 2N ＋ 1 automata with FitzHugh-Nagumo dynamics, in which one is set to be oscillatory and the others are excitable, is investigated with hi-directional interactions. We find that 1 ： 1 rhythm propagation in the array depends on the appropriate couple strength and the excitability of the system. On the two sides of the 1 ： 1 rhythm area in parameter space, two different kinds of dynamical behaviour of the pacemaker, i.e. phase-locking phenomena and canard-like phenomena, are shown. The latter is found in company with chaotic pattern and period doubling bifurcation. When the coupling strength is larger than a critical value, the whole system ends to a steady state.     

反应扩散系统中波传播的锁频现象

在空间延展系统中,当增强外部光强时,作者观察到波传播的N：N-1（N≥2）锁频现象.此现象是在光敏BZ反应实验中观察到的.通过构建一个映射函数,发现在波周期和外部光强的关系中存在魔鬼阶梯,并且此阶梯与实验数据相吻合.     

黄原胶溶液中法拉第斑图色散关系的修正

质量一定、受竖直简谐驱动的液体表面在一定条件下会产生稳定驻波图样,即法拉第斑图.对于黄原胶溶液斑图系统,朗道的经典表面重力张力波色散关系仅适用于低频区域.为了使更大频率范围内色散关系成立,需要考虑黏滞耗散及剪切稀化效应,作出理论修正.分析表明,黏滞耗散为斑图系统的色散关系引入了频率的四次方依赖项;剪切稀化效应在高频下弱...     

非线性热对流斑图实验

搭建了非线性热对流斑图实验装置,在对流水层上下表面形成稳定的温度差,并通过改变温度差实现了远离平衡态的开放系统从无序到有序的自组织转变过程.利用阴影法对对流斑图的发生、发展和演化的过程进行了可视化观察.     

Responses of a Noisy Excitable System to External Signals with Different Periods

The behaviour of an excitable system under Gaussian white noise and external periodic forcing is systematically studied. In a large range of noise intensity, the n:l phase locking patterns are obtained for certain ranges of the input periods, where n input periods give one spike. In the phase locking regimes, the system presents low noise-to-signal ratios and shows better regularities. Out of the regimes the system behaves less regularly and the relations between the noise-to-signal ratio and the noise intensity exhibit typical stochastic resonance phenomena.At a higher noise level, the system shows the characteristic behaviour of the noise.     

竖直周期外驱力下的颗粒碰撞自组织研究

对竖直方向振动诱导的颗粒碰撞进行了理论和实验的探究.按照近似原则选取恰当参量,在准理想气体近似下对颗粒系统做极限假设,用热力学方法分析系统得出系统状态量服从的微分方程,针对该方程不可解析求解问题,提出了有效的修正方法并做级数修正.基于热力学输运和逐级展开研究受竖直驱动的颗粒系统的碰撞,展示了对颗粒系统的的研究思路,对文献中没有指明的恒温近似做进一步处理,给出温度分布方程和一阶修正,证明该近似在实验条件下成.     

蜂蜜溶液法拉第斑图的研究

本文研究周期性外力驱动下蜂蜜溶液法拉第斑图的特性.实验中观察到相较于水或黄原胶溶液,蜂蜜溶液的法拉第斑图具有很高的有序度.对产生斑图的临界加速度进行了探究,发现蜂蜜溶液与黄原胶溶液在弱非线性区具有相似的动力学特性.关于色散关系的测量结果显示,蜂蜜溶液色散关系与重力-表面张力波理论色散关系有较好的一致性,但蜂蜜溶液的非牛顿黏滞性导致两者有所差异.