A variable structural control of a serially connected string

A variable structural control of a serially connected string is concerned in this paper. The system is formulated by partial differential equations with the boundary conditions. The eigenvalues and eigenfunctions of the system operator are discussed in the appropriate Hilbert spaces. A variable structural control is applied to the serially connected beam and it has been shown that the actual variable stractural mode of the system can be approximated by ideal variable stractural modes in any accuracy under certain conditions. In this paper, a significant semigroup property of restriction of the system operator is derived.