Using division with remainder of matrix polynomials and structural features of unbounded Hamiltonian operator,the plate bending problems arising from elasticity and two kinds of un-bounded Hamiltonian operator families are considered,the eigenvalues and the corresponding generalized eigenfunctions of those two kinds of unbounded Hamiltonian operators are calculat-ed,and the properties generalized eigenfunctions are studied.The completeness of the eigen-functions is proved in the sense of Cauchy principal value.This method is also extended to a class of 4th PDEs with constant coefficients,and the completeness theorem is obtained,and the general solutions of two kinds of Hamiltonian systems are given. |