关于二次微分系统I类方程的极限环

On Limit Cycles of Type I Equation of Quadratic Differential Systems

本文研究二次微分系统Ｉ类方程ｄｘ／ｄｔ＝－ｙ＋δｘ＋ｌｘ２＋ｍｘｙ＋ｎｙ２，ｄｙ／ｄｔ＝ｘ的极限问题，得到了当ｌ＝０时大范围内存在极限环的条件，并探讨了与之有关的分界线环和分歧曲线的存在问题．

In this paper, the problem on limit cycles of Type I equation of quadratic differential systems dx/dt=-y+δx+lx 2+mxy+ny 2,dy/dt=x has been researched. It obtained the existential condition of limit cycles on large range when l=0 .Furthermore, the paper also discussed the existence problem of boundary line cycles (strange limit cycles) and bifurcation curve.