This paper discuss the solving motheds for Dirichlet problems on the ring area,give its solving process its solution form of Fourier series,this have great significance for understanding the eigen-value problems of Laplace equation on the various boundary conditions,especially on the nature boundary condition and periodic boundary condition.

The Hamiltonian analytical method for Stokes flow problems in an annular cavity;

A new method on order reduction for diserete time stochastic system is presented in this paper,viz:order reduction with state covariance and pole ring bounds.