This paper proposes a bi-stable permanent magnetic actuator (PMA) for medium voltage vacuum circuit breaker. The structure of the proposed PMA is discussed and the optimization of the structure is carried out. The model of finite element analysis (FEA) is constructed where the flux distributions, electromagnetic force under different structure parameters are analyzed. The feasibility and correctness of the PMA are verified by the FEA simulation results and the optimal size for movable plunger and stationary iron ring is obtained.

In this paper, an explicit dynamic finite element model is built to study the compressive forming technology used in the metal connector of transmission lines of power system. Additionally, to improve the calculation accuracy, an optimized reversed calculation method for determining the equivalent friction coefficients is designed and coupled into the dynamic finite element model. It is validated with a carefully designed experiment that the coupled dynamic finite element model is effective in describing the plastic flow and in determining the grip strength of the compressive forming structure. Finally, with the dynamic finite element model, an optimized compressive forming process window is obtained for controlling the formation of edge flaws while keeping sufficient grip strength.

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This article analyzes the forward kinematics and inverse kinematics of the seven-degree-of-freedom exoskeleton rehabilitation manipulator. Denavit–Hartenberg coordinates are used to model the forward kinematics, and the working space of the end effector of the manipulator is analyzed according to the joint motion range of the human arm. In the inverse solution of the seven-degree-of-freedom exoskeleton rehabilitation manipulator, the self-motion angle [Formula: see text] of the elbow is used. The minimum energy standard is used to calculate the self-motion angle [Formula: see text]. The minimum energy mainly includes the gravitational potential energy of the upper limbs and the elastic potential energy stored in the muscles. Thus, the inverse solution formula of the seven-degree-of-freedom exoskeleton rehabilitation manipulator is derived. When calculating the angle [Formula: see text], an auxiliary parameter is introduced to solve the self-motion manifold of the manipulator. Finally, the theoretical derivation and verification of the forward and inverse kinematics are carried out in this article, and through analysis of the results, it is concluded that the inverse kinematics of this article has some limitations but the theory of inverse kinematics is feasible.

A common source of noise is operational excitations of mechanical devices, which cause vibrations and thus sound radiation from their surfaces. Plate and shell structures in transformer, vehicle or airplane applications vibrating in resonance show particularly high noise levels. Classic methods of noise reduction such as passive damping or anti-noise are not efficient enough in certain cases. Therefore, the use of structural control for reduction of sound radiation is presented in this paper. A piezoelectric ceramic actuator (PCA) for the active noise control is also proposed. The structure of the proposed PCA is discussed and the control method of the structure is carried out. The proposed PCA has excellent performance compared with conventional ones, such as more force, convenient installation and disassembly. The active noise control (ANC) system and control algorithm are also discussed in this paper. The performance of the proposed controller is analyzed through simulation in the Matlab/Simulink.