This paper gives an exact solution for free vibration of a physically nonuniform straight bar with varying section by the use of a class of integrable linear ordinary differential equation.
By applying a fixed point theorem, the authors study the existence of positive periodic solutions to a class of differential equations with stated-dependent delay.
运用不动点定理，研究一类具状态依赖时滞的微分方程周期正解的存在性。
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The problem of minimum_energy optimal control for multivariable linear systems determined by a class of differential operator matrixes is investigated.