Firstly the interval perturbation robustness of an optimal schedule was defined, that was the property that an optimal schedule keeps the same when some of the parameters in the scheduling problem vary in some intervals.

Matrix perturbation methods for eigenvalue analysis of vibration of compressible fluid-solid;

A perturbation method for weakly damped systems repeated eigenvalues;

An analytical solution to tunnels with over-under-excavated surface based on perturbation method;