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actuation-mechanism
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Investigation of the mechanical behaviors of carbon nanotubes under electrostatic actuation using the modified couple stress theory
, Article Fullerenes Nanotubes and Carbon Nanostructures ; Volume 21, Issue 10 , Oct , 2013 , Pages 930-945 ; 1536383X (ISSN) ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
2013
Abstract
The paper presents size-dependant mechanical behaviors of carbon nanotubes under electrostatic actuation using modified couple stress theory. The behaviors of the carbon nanotubes with different geometries and boundary conditions are studied in detail. The results reveal that application of this theory results in higher pull-in voltages for both cantilever and doubly clamped boundary conditions
Wideband tunable photonic crystal cavity with electrostatic actuation
, Article 2012 IEEE Photonics Conference, IPC 2012, 23 September 2012 through 27 September 2012 ; September , 2012 , Pages 266-267 ; 9781457707315 (ISBN) ; Sodagar, M ; Eftekhar, A. A ; Mehrany, K ; Rashidian, B ; Adibi, A ; Sharif University of Technology
2012
Abstract
We present a wideband tunable optical cavity based on electrostatic actuation. Over 60nm shift in wavelength is achieved by applying less than 1 Volt corresponds to a mechanical displacement of 30nm
Design and Analysis of an Actuating Robot to Employ Manual Endo-Wrist Laparoscopic Instruments in a Robotic Surgery System
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor) ; Hoviattalab, Maryam (Co-Advisor)
Abstract
This research describes the design and analysis of an actuating robot to manipulate the disposable Endo-wrist robotic surgery instruments. Analyzing the mechanism of common manual Endo-wrist instruments, it was found that the rotations of handle of the instrument are transferred to its wrist using a snake-like element and four connecting cables. Based on this observation, a 2DOF parallel actuating robot was designed to rotate the instrument handle, in which the degrees of freedom are controlled by two linear spindle motors. The Inverse kinematic analysis of the manual instrument was performed by minimizing the potential energy of cables. Also the inverse kinematic solution of the actuating...
Dynamic analysis of carbon nanotubes under electrostatic actuation using modified couple stress theory
, Article Acta Mechanica ; Vol. 225, Issue 6 , June , 2014 , pp. 1523-1535 ; Online ISSN: 1619-6937 ; Rastgoo, A ; Ahmadian, M. T ; Mashhadi, M. M ; Sharif University of Technology
Abstract
Modified couple stress theory is a size-dependent theorem capturing the micro/nanoscale effects influencing the mechanical behaviors of the micro- and nanostructures. In this paper, it is applied to investigate the nonlinear vibration of carbon nanotubes under step DC voltage. The vibration, natural frequencies and dynamic pull-in characteristics of the carbon nanotubes are studied in detail. Moreover, the effects of various boundary conditions and geometries are scrutinized on the dynamic characteristics. The results reveal that application of this theory leads to the higher values of the natural frequencies and dynamic pull-in voltages
Dynamic behaviours of carbon nanotubes under dc voltage based on strain gradient theory
, Article Journal of Physics D: Applied Physics ; Volume 46, Issue 40 , 2013 ; 00223727 (ISSN) ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
2013
Abstract
The paper deals with scrutinizing the vibration and dynamic pull-in behaviours of carbon nanotubes with different dimensions and boundary conditions. The strain gradient theory as a nonclassical elasticity theorem is applied in this research to compensate the limitations of the classical theories in predicting the mechanical behaviours of the micro- and nanostructures in general and carbon nanotubes, in particular under electrostatic actuation. The results reveal that the mechanical properties of carbon nanotube (CNTs) computed using the strain gradient theory differ significantly with those obtained from the classical theory. The strain gradient theory leads to higher stiffness and pull-in...
Experimental study of a novel Magneto Mercury Reciprocating (MMR) micropump, fabrication and operation
, Article Sensors and Actuators, A: Physical ; Volume 194 , 2013 , Pages 277-284 ; 09244247 (ISSN) ; Salari, A ; Shafii, M. B ; Sharif University of Technology
2013
Abstract
Today, MEMS have wide applications in modern technologies. Magneto hydro dynamic (MHD) micropumps play an important role in the MEMS industry and have been thoroughly studied in the recent years. In this study, the idea of classic reciprocating micropumps was combined with magneto hydro dynamics (MHD) to develop a novel Magneto Mercury Reciprocating (MMR) micropump. To attain this goal, the Lorentz force, as the actuation mechanism, was used to move a conductive liquid (mercury) slug in a reciprocating manner in order to suck the working fluid (air) from the inlet and pump it to the outlet. The performance of the fabricated MMR micropump was examined in terms of parameters such as pressure...
Design and Implementation of an Activation Mechanism for Wristed Laparoscopic Instruments at Sina Robotic Surgery System
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor)
Abstract
Sina surgical system is a telesurgery robotic system which is capable of using the conventional laparoscopic tools. In order to provide the wrist degree of freedom and increase the surgical maneuverability, a mechanism is introduced here which enables Sina to use and activate the wristed laparoscopic instrument Laparo-Angle. At first, the kinematics and dynamics characteristics of Laparo-Angle were identified experimentally. This tool contains 4 degrees of freedom, pitch, yaw, grasp and distal Roll. Activation of pitch and Yaw degrees of freedom requires a mechanism which at least has two rotational degrees of freedom to move the tool handle in a cone shape workspace with an apex angle of 36...
Conceptual design of a miniaturized hybrid local actuator for Minimally Invasive Robotic Surgery (MIRS) instruments
, Article Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS ; 2011 , Pages 2140-2143 ; 1557170X (ISSN); 9781424441211 (ISBN) ; Mirbagheri, A ; Farahmand, F ; Sharif University of Technology
Abstract
The actuation mechanism of the tip of an endoscopic instrument is a major problem in designing miniature scale motorized instruments, especially when a high level of functionality and multi degrees of freedom (DOF) are concerned. We evaluated the different possible actuation methods for an endoscopic needle holder and proposed a new design of hybrid local-actuation, including a micro DC motor and a piezoelectric (PZT) actuator. The DC motor provided the long movement course required for opening-closing function of the gripper while the PZT guaranteed the high gripping force required for holding the needle. A compact serial configuration was considered for the actuators, producing an overall...
Rotary magnetohydrodynamic micropump based on slug trapping valve
, Article Journal of Microelectromechanical Systems ; Volume 20, Issue 1 , December , 2011 , Pages 260-269 ; 10577157 (ISSN) ; Shafii, M. B ; Sharif University of Technology
2011
Abstract
A novel rotary magnetohydrodynamic (MHD) (RMHD) micropump is presented in this paper in order to both benefit exclusive advantages from the MHD micropumps and eliminate the current obstacles in their implementation. Lorentz force, which is the actuation mechanism in RMHD, is used to propel a mercury slug in a circular microchannel in order to suck the working fluid from the inlet and pump it to the outlet. This idea is integrated with a valve which prevents the working fluid from passing through, while allowing the mercury slug to pass, during each pumping loop. The performance of a fabricated RMHD is evaluated, considering parameters such as pressure difference, running duration, electric...