Nonlinear Analysis of an Electrostatically Actuated Microbeam Considering Coupled Vibrations Due to Rotation

, Ph.D. Dissertation Sharif University of Technology Mojahedi, Mahdi (Author) ; Ahmadian, Mohammad Taghi (Supervisor) ; Firoozbakhsh, Keikhosrow (Supervisor)

Abstract

This research is concerned with the study of the static, dynamic, vibration and instability of an electrostatically actuated microbeam gyroscope considering geometric nonlinearities and electrostatic fringing fields. A vibrating microbeam gyroscope consists of a beam with a rigid (proof) mass attached to it and undergoes coupled flexural-flexural vibrations coupled with base rotation. The primary oscillation is generated in drive direction of the microbeam gyroscope by a pair of DC and AC voltages on the mass. The secondary oscillation occurring in the sense direction is induced by the Coriolis coupling caused by the input angular rate of the beam along its axis. In this case gyroscope acts...

Power System Voltage Stability Margin Assessment Using Synchronous Wide Area Measurement System (WAMS)

, M.Sc. Thesis Sharif University of Technology Mohammad Amini, Alireza (Author) ; Parniani, Mostafa (Supervisor)

Abstract

Although voltage control and stability issues are not new to the electricity industry, but nowadays, in most modern power systems, special attention has been paid to this issue. Once, only weak systems with long lines were involved in voltage instability, while today due to heavy loading, voltage stability is a serious concern even in developed networks. Over tim, with increasing demand for electricity and emergence of electricity market and economic constraints, power systems are more exposed to voltage instability and even voltage collapse. Therefore, reliable operation of the system in such circumstances requires evaluating voltage stability of the network at both stages of planning and...

Production of Liquid Metal Micro-droplets and Electrical Control of their Size and Rate of Formation

, M.Sc. Thesis Sharif University of Technology Asiabi Mollahaji, Arezoo (Author) ; Kebriaee, Azadeh (Supervisor)

Abstract

The use of liquid metal droplets due to their high electrical and thermal conductivity are used in various industries today. One of the methods of producing these micro-droplets is the flow focusing method, which is widely used to produce integrated and monodispersed droplets. Liquid metals have high surface tension and these micro-droplets are formed only if there is sufficient shear force between the liquid metal and a continuous fluid phase. In the past, they used several different methods such as pressure fluctuations and changes in continuous phase flow rate to control the shear force and produced polymer, gas, etc. micro-droplets.In this research, use the electric potential to control...