We investigate the response of an excitable medium to a localized perturbation in the presence of a two-dimensional smooth chaotic flow. Two distinct types of flows are numerically considered: open and closed. For both of them three distinct regimes are found, depending on the relative strengths of the stirring and the rate of the excitable reaction. In order to clarify and understand the role of the many competing mechanisms present, simplified models of the process are introduced. They are one-dimensional baker-map models for the flow and a one-dimensional approximation for the transverse profile of the filaments.
We disclose a new class of patterns, called patched patterns, in arrays of non-locally coupled excitable units with attractive and repulsive interactions. Self-organization process involves formation of two types of patches, majority and minority ones, characterized by uniform average spiking frequencies. Patched patterns may be temporally periodic, quasiperiodic or chaotic, whereby chaotic patterns may further develop interfaces comprised of units with average frequencies in between those of majority and minority patches. Using chaos and bifurcation theory, we demonstrate that chaos typically…
具有粘性摩擦的地震断层的Burridge-Knopoff模型等价于具有弹性耦合的可激发介质的van der Pol-FitzHugh-Nagumo模型。我们在Burridge-Knopoff模型中使用的润滑蠕变滑动摩擦定律描述了一系列实际材料的摩擦滑动动力学。包括同步振荡和传播锋在内的低维结构占主导地位，这与实验室摩擦实验的结果一致。在这里，我们探讨弹性可激发介质中的前沿动力学。
An expression for the group delay of the FitzHugh-Nagumo model in response to low amplitude input is obtained by linearisation of the cubic term of the voltage equation around its stable fixed-point. It is found that a negative group delay exists for low frequencies, indicating that the evolution of slowly fluctuating signals are anticipated by the voltage dynamics. The effects of the group delay for different types of signals are shown numerically for the non-linearised FitzHugh-Nagumo model, and some observations on the signal aspects that are anticipated are stated.
Dynamic multiphase flow triggers chaotic mixing in porous media
University of Oslo（奥斯陆大学）；Norwegian University of Science and Technology（挪威科技大学）；University of Copenhagen（哥本哈根大学）；Univ. Grenoble Alpes（格勒诺布尔阿尔卑斯大学）；Univ. Savoie Mont Blanc（萨瓦蒙布朗大学）；Univ. Gustave Eiffel（古斯塔夫·埃菲尔大学）；Université de Rennes（雷恩大学）
