Stability And Periodicity To Solutions Of Two Types Biological Models

This thesis mainly studies asymptotic stability and periodic of two types biological models. It is consists of three chapters.In Chapter1, introduce issues arising from the historical background and main tasks of this article.In Chapter2, discuss asymptotic stability and exponential stability of a2-dimensional impulsive differential equation model of plankton allelopathy. By means of piecewise continuous functions which are modifications of classical Lya-punov’s functions we give sufficient conditions for asymptotic stability of the so-lutions.In Chapter3, discuss asymptotic stability and Periodicity of a3-dimensional impulsive competitive system.It is shown that if the coefficients are continuous,periodic and satisfy certain average conditions then a positive periodic solution there exists which is globally asymptotically stable.