考虑二阶微分方程组{x"+H(t)x'+A(t)x=F(t,x),0〈t〈T,x(0)=x(T),x'(0)=x'(T).正周期解的存在性。利用Krasnoselskii不动点定理以及所对应的格林函数正性,证明上述二阶微分方程组新的正周期解的存在定理,将所得结论进行推广,得到上述二阶微分方程组多个正周期解的存在定理。将结论应用在经典实例上,验证了所得结果的正确性。
The existence of positive periodic solutions for the following second order differential equations is considered.{x"+H(t)x'+A(t)x=F(t,x),0〈t〈T,x(0)=x(T),x'(0)=x'(T). First of all, by using the Krasnoselskii fixed point theorem and the positivity of the Green' s function, the new existence theorem of positive periodic solutions of the equations is obtained ; Then, the above main conclusions are generalized to existence theorem of multiple positive periodic solutions ; Finally, a classic example is tested to present the value of the main results.