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Silver in the form of AgNO 3 was added to ZnO-based varistor ceramics prepared by the solid-state reaction method. The effects of AgNO 3 on both the microstructure and electrical properties of the varistors were studied in detail. The optimum addition amount of AgNO 3 in ZnO-based varistors was also determined. The mechanism for grain growth inhibition by silver doping was also proposed. The results indicate that the varistor threshold voltage increases substantially along with the AgNO 3 content increasing from 0 to 1.5mol%. Also, the introduction of AgNO 3 can depress the mean grain size of ZnO, which is mainly responsible for the threshold voltage. Furthermore, the addition of AgNO 3 results in a slight decrease of donor density and a more severe fall in the density of interface states, which cause a decline in barrier height and an increase in the depletion layer.

A synchronous control system of virtual main-axis based on extended sliding mode disturbance observer is designed to solve some problems that coupling of multi-axis synchronous control of electronic gears is low and has poor anti-interference ability, and a large amount of synchronization error callback overshoot in bag-making machines. First, a velocity compensator is designed in order to establish the coupling relationship between the virtual and traction motor. Second, a nonsingular terminal sliding mode controller and a disturbance observer are used to enhance the anti-disturbance capability of the system. Finally, by using MATLAB/Simulink simulation, the viability and superiority of the method in multi-axis synchronous control are proved. The simulation results demonstrate that the control method decreases the synchronization error and the callback overshoot between the traction motors, and enhances the coupling performance and anti-interference ability of the system, which has a more significant impact on the high-performance synchronization control for the multi-traction motor system of the bag-making machine.

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