Electrostatic actuated mems for precision AC voltage references
The purpose of this paper is to present results on the design of electrostatic actuated micro- electromechanical systems (MEMS) aiming at developing AC voltage references through mechanical-electrical transduction for electrical metrology and more generally for miniaturized instrumentation. Several test MEMS architectures (targeted AC voltages from 10 V up to 100 V) for the vertical motion have been designed and are under fabrication by an epitaxial silicon on insulator (SOI) surface micromachining process with the aim to investigate the potentialities of the different structures with respect to the geometrical dispersion, the strain sensitivity and the electrical stability.
Dielectric charging in radio frequency microelectromechanical system capacitive switches: A study of material properties and device performance
The paper analyze the direct relation between the dielectric polarization mechanisms and the radio frequency microelectromechanical system capacitive switches performance. The dielectric polarization mechanisms are investigated in metal-insulator-metal capacitors with the aid of the thermally stimulated depolarization current method. The performance of microelectromechanical system is studied through the temperature dependence of the bias for the minimum capacitance. The simultaneous assessment allows the discrimination of dipolar and space charge polarization that allows the prediction of the shift of capacitance minimum with temperature.
Column Axial Load Effects on Performance of Panel Zone in Welded-Flange-Plate Connections
In this study the effects of different levels of column axial load on seismic performance of Welded Flange Plate (WFP) connections with different panel zone strength are presented. Finite element method was used to do this investigation and reliability of the modelling method was verified by comparison with experimental available records in documents. Fifteen sub-assemblages of WFP connections were generated by means of ABAQUS software. The aim was to enhance the knowledge about the consequence of column axial load level on cyclic behaviour and fracture potential of the connections with different panel zone strength for external joints in Steel Moment Resisting Frames (SMRFs). Results showed that cyclic behaviour including hysteresis loops and energy dissipation were not affected significantly by increasing column axial load regardless of the panel zone strength. It was also found that increase of the fracture potential due to increase in column axial load became less pronounced when the panel zone strength was decreased.