A numerical approach is presented for simulating the stability of harmonic resonance overvoltage in power systems and the relationship is discussed between the stability of harmonic solutions and the change of parameters of system by using the methods of Galerkin and Runge Kutta.It can be used for describing further bifurcation phenomenon in power systems.

A numerical approach is presented for simulating the quality of natural ventilation in an apartment unit with three bedrooms and one hall by using algorithm of Simpler and Artificial compressing method based on blocked interior spaces,which obtained the main data on the distribution of laminar-flow field in a housing unit. The application software created accordingly applies universally,which provides an effective means for an alyzing,optimizing and evaluating the quality of natural ventilation in housing design.

The approximate analysis of differential systems by applying the theory of regional analysis, is described. It supplies a formularization and calculating programme for algebraic limit cycle of second degree in a type of differential systems of third degree, and also for critical value of damping resistance in power systems. This new method simplifies the traditional method, hence it is acceptable and applicable for engineers. Finally, a few of examples are given based on this method.