用最小作用原理研究具有次线性的非线性项2阶系统
Research Second Order Systems with Sublinear Nonlinearity by the Least Action Principle

利用最小作用原理研究2阶系统ü(t)-A(t)u(t)=?F(t,u(t)),a.e.t∈[0,T]u(0)-u(T)=(u)(0)-(u)(T)=0,的周期解的存在性,在非线性项是次线性及A(t)是1个连续N阶对称矩阵的条件下得到了该系统的2个新的存在性定理.
The existence of periodic solutions of the following second order systems {ü(t)-A(t)u(t)= ??SymbolQC@ F(t,u(t)), u(0)-u(T)=u(0)-u(T)=0,a.e.t∈[0,T] is studied by the least action principle.When the nonlinearity is sublinear and A(t) is a continuous symmetric matrix of N is a continuous symmetric matrix of der,two new existence theorems of this system are obtained