This paper studies the stability of in-phase solutions in a class of coupled systems and gives a sufficient condition for stability of the in-phase solutions in coupled Oreg-onators.

It studies the in-phase solution and out-of-phase solution of linear difference coupledsystem of Poincare equation,gets the parameter domain in which the in-phase solution is sta-ble,and establishes the existence and stability theorem of out-of-phase solution in diagonal dif-ference coupling.

The feasibility of square wave driving were demonstrated,adding phase shift element in self-excited driving circuit was presented,to make the Micro Quartz Tuning Fork Gyroscope s driving oscillation frequency equal to it s mechanical resonant frequency,the switch synchronous phase sensitive demodulation s application in det.

By introducing first the concept of coset in the sub-space of linear space,we have testified an im- portant property of the coset and finally give the necessary and sufficient condition for the same solution of the solva- ble nonhomogeneous linear equations.

Analytic method and appliction about intersection line of fault and coal seam on the conditions of same dip of fault and coal seam;

And a procedure is developed to create in-phase crossover network.