本文研究了具有时滞的三种群食物链模型的分支问题.利用分支理论及Nyquist准则等方法,获得了系统永久持续生存和正平衡点附近发生Hopf分支的条件.文中进一步研究得到了系统保持稳定的最大时滞长度,从而可以了解并控制种群密度发生异常振荡,推广了已有文献的结果.
A kind of three-species food chain model with time delays is considered.With the theory of Hopf bifurcation and Nyquist rule,the conditions of the permanence and the positive equilibrium of Hopf bifurcation is given.Further,the estimation of the length of delay to preserve stability has also been calculated,which gives the idea and will prevent the abnormal oscillation in population density.This researches extends the previous results.