arXiv subjects

Chunhua Ou

Publications and source records attributed to Chunhua Ou.

4 recordsLinked to original sources

arXiv2022

A time-periodic competition model with nonlocal dispersal and bistable nonlinearity: propagation dynamics and stability

Seasonality frequently occurs in population models, and the corresponding seasonal patterns have been of great interest to scientists. This paper is concerned with traveling waves to a time-periodic bistable Lotka-Volterra competition system with nonlocal dispersal. We first establish the existence, uniqueness and stability of traveling wave solutions for this system. Then, by utilizing comparison principle and the stability property, the relationship among the bistable wave speed, the asymptotic propagation speeds of the associated monotone subsystems and the speed of upper/lower solutions is obtained. Next, explicit sufficient conditions for positive and negative bistable wave speeds are derived. Our explicit results are derived by constructing particular upper/lower solutions with specific asymptotical behaviors, which can be seen as case studies shedding light on further studies and improvements. Finally, the theoretical results are corroborated under weak conditions by direct simulations of the underlying time-periodic system with nonlocal dispersal. The combined impact of competition, dispersal and seasonality on the invasion direction has shed new light on the modelings and analysis of population competition and species invasion in heterogeneous media.

math.AP↗

arXiv2020

Speed Selection for Reaction Diffusion Equations in Heterogeneous Environments

Reaction-advection-diffusion equations, in periodic settings and with general type nonlinearities, admit a threshold known as the minimal speed of propagation. The minimal speed does not have an accessible formula when the nonlinearity is not of KPP type, for instance. The question becomes whether the minimal speed can be obtained through a linearization procedure or not. In this paper, we derive selection criteria for the minimal speed: a key feature of the nonlinear selection is unveiled. Moreover, we use upper/lower solution techniques in order to derive practical criteria determining the minimal speed in the presence of advection and a general type nonlinearilty.

math.AP↗

arXiv2011

Exponential and Algebraical Stability of Traveling Wavefronts in Periodic Spatial-Temporal Environments

Global stability of traveling wavefronts in a periodic spatial-temporal environment in $n$-dimension ($n\ge 1$) is studied. The wavefront is proved to be exponentially stable in the form of $ O(e^{-μt})$ for some $μ>0$, when the wave speed is greater than the critical one, and algebraically stable in the form of $O(t^{-n/2})$ in the critical case. A new and easy to follow method is developed. These results are then extended to the case of time-periodic media. Finally, we illustrate how the stability result can be directly used to obtain the uniqueness of the wavefront with a given speed.

math.AP↗

arXiv2004

Periodic Oscillations of Blood Cell Populations in Chronic Myelogenous Leukemia

We develop some techniques to prove analytically the existence and stability of long period oscillations of stem cell populations in the case of periodic chronic myelogenous leukemia. Such a periodic oscillation $p_\infty $ can be analytically constructed when the hill coefficient involved in the nonlinear feedback is infinite, and we show it is possible to obtain a contractive returning map (for the semiflow defined by the modeling functional differential equation) in a closed and convex cone containing $p_\infty $ when the hill coefficient is large, and the fixed point of such a contractive map gives the long period oscillation previously observed both numerically and experimentally.

q-bio.TO↗