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Magnetic reconnection is a fundamental mechanism for energy conversion in the realms of space physics, astrophysics, and plasma physics. Over the past few decades, obtaining analytical solutions for three-dimensional (3D) magnetic reconnection has remained a challenging endeavor. Due to the complexity and nonlinearity of the equations, analytical solutions can only be obtained when specific spatiotemporal distributions of magnetic fields or plasma flows are provided. Particularly, the evolution of reconnection flows in time-dependent 3D reconnection has not been analytically discussed. Additionally, quasi-steady magnetic reconnection persisting for several hours can be observed in the turbulent solar wind, which raises an important question: can steady reconnection flows theoretically exist in a time-dependent 3D magnetic reconnection model? In this study, a generalized analytical model for time-dependent kinematic 3D magnetic reconnection has been constructed. In the framework of pure analytical approach, it is firstly demonstrated that steady reconnection outflows can theoretically exist within a time-varying magnetic field. We have also analytically discussed the possibility of the existence of quasi-steady reconnection flows in 3D magnetic reconnection for turbulent magnetic fields in the solar wind. These findings broaden our understanding of the stability and necessary conditions for time-dependent 3D magnetic reconnection, offering new insights into quasi-steady reconnection phenomena in real cosmic environments.

The study of the dynamic characteristics of MEMS micro-devices depends on relevant testing facilities. Testing with a base excitation method was studied and employed in practical tests. A system for the dynamic characteristic testing of MEMS micro-devices was built based on a PZT transducer as the shock excitation source. A high voltage power source for the PZT transducer, which can provide large transient current, was developed for impact generation. Experiments for testing micro piezoelectric cantilevers were accomplished with the base excitation method. The impact response, i.e. electric charge signal generated by the micro piezoelectric cantilever, was acquired. By performing spectral analysis and comparison of the result with another cantilever having different resonance frequencies, the resonance frequency of the tested microstructure was determined. For comparison, simulation of the piezoelectric cantilever with a finite element analysis (FEA) method was carried out. Because the theory analysis is in good agreement with the experiment results, it can be used to estimate the actual resonance frequency of the tested microstructure. The base excitation method was also applied in the dynamic testing of microstructures under a high-gforce environment. By the exclusion of the resonance peaks of PZT transducer and noise frequencies, the resonance frequency of the tested microstructure was determined. The applicability and the limitation of the method were briefly discussed. [ABSTRACT FROM AUTHOR]