Based on this model,the expressions of critical field for the irreversible reversal magnetization and the coercive force are derived for both the parallel rotation and symmetric fanning mechanisms.

It is found that zero shifting of level detection system,secondary cooling and segment alignment have a conssderable influnce on the stability of mould level.

Forming technology of the unsymmetrical workpiece;

Differential protection based on waveform symmetry is furtherly studied and analyzed through a mal-operation incident when the unloaded power transformer is connected to the power system.

In consideration of the frequent mal-operation of transformer differential protection based on the principle of waveform symmetry, this paper analyzes the internal relationship of the waveform symmetry principle and the secondary harmonic restraint principle based on the generating mechanism of the magnetic inrush current of the three-phase transformer.

In connection with analyzing operation of two differential protections for transformer, The criterias for exciting current of differential protection were compared,and further explanation for the principle of waveform symmetry.

In this paper,we define a codazzi tensor on conformally symmetric space,and induce an operator,which is self-adjoint relative to the L2-inner product.