فهرست مطالب moharam habibnejad

The elasticity modules of the micro/Nanoparticles, especially biological particles are measured using different tools such as atomic force microscopy. The tip of the atomic force microscopy as an indenter has different shapes such as spherical, conical and pyramidal. In the contact of these tips and biological cells, avoiding the cell damage is a necessity. The goal of this paper is investigation and comparison of different tips’ geometries. Different tip’s geometries and their related theories were collected and proposed. To generalize theories’ application for any kind of particle (even non-biological particles) some of simplifying assumptions used in these theories, such as tip rigidity, were removed. Simulation of the force- indentation depth was done for gold nanoparticle and observed that if simplifying assumptions were not removed there would be big errors in calculating the elasticity module of some particles. Then, simulations were done for two yeast and mouse embryo cells. For both cells, in general, the geometry of the curve group, the geometry of the pyramidal group and finally the geometry of the conical group were positioned from the highest to the lowest places. For hyperbolic, conical and pyramidal tips, the important parameter was semi vertical angel. To observe its effect, different magnitudes of this parameter were simulated. According to observed results in three investigated geometries and for both cells, bigger semi vertical angel created higher curves and this means in bigger angels the possibility of cell damage is higher.

In this study, feedback linearization (FL) for 6R manipulator is designed, simulated and implemented. The presented input-output FL controller has achieved the desired performance for the complicated nonlinear terms in the arm’s dynamic equations. Simulations were used to test the performance of the controller for point-to-point motion as well as continuous trajectory. The results of the point-to-point motion simulations and experiments were compared, where it indicates that the proposed approach preserved smooth motion in a very short process time with good accuracy. The dynamic load carrying capacity (DLCC), which is a criterion to determine FL controller performance on 6R robot, is also investigated, based on saturated torque of the motors and allowable error bounds. Moreover, it was shown that the control law is able to accurately represent closed-loop equations and simultaneously imposed desirable behavior on 6R robot.

The behavior of frequency response of the cantilever of the atomic force microscopy was different in the liquid environment in comparison with air environment. In this research, the dynamic analysis of atomic force microscopy in the air and liquid environments have been carried out with consideration of linear and non-linear interaction forces and also the effect of geometrical parameters such as length, width, height and angle between cantilever and sample's surface on the rectangular cantilever has been investigated. A rectangular beam based on the Timoshenko beam model has been simulated in ADAMS software environment and more accurate results has been received by considering the probe tip and the angle location of cantilever at simulation.At the end of the beam, a silicone tip has been considered that the applied forces on it have been approximated with two tangential and vertical springs and the vibrational simulation of cantilever at two states has been carried out with regard to linear and non-linear interaction forces.The amplitude and resonance frequency of the simulated beam based on Timoshenko model is different from obtained results of Euler beam model Due to the effect of shear deformation and rotary moment in Timoshenko beam.Therefore, the Timoshenko beam model has the better accuracy in comparison with Euler beam model.Many chemical and biological processes occurred so fast so using of short cantilever for increasing the speed of imaging at impact mode in liquid environment was very necessary. Eventually short beam that has been modeled based on Timoshenko model can produce more accurate results. This paper aimed to show that the amplitude and resonance frequency of vibration in the liquid environment were different from amplitude and frequency of vibration in the air environment due to the damping coeficient and added mass of liquid.

In this article, the advantages of navigation based on dual tone multiple frequencies (DTMF) technique through telecommunication lines is studied. First, the calculations of direct and inverse kinematics of the manipulator in computer are transferred to the PIC microprocessors center. Next, each PIC is required to control and automate the relevant link separately. The main purpose of this work is making it possible to control the robot via a telephone line and without a modem. In order to apply this idea, computer is analyzed the data which received from the operator and insert the necessary instructions through the serial port using AVR microcontroller in the embedded hardware at the phone line and sends them to the hardware of the robot. Then the robot is performed the processes as a closed loop design and provides the necessary feedback for the computer. Real-time control, low volume of software and hardware computations and the possibility of using the phone lines with low and medium bandwidth in addition to ADSL lines simultaneously are the special features of this method. In the proposed method, control data and the corresponding feedbacks are transmitted as the remote closed loop control, which can be combined in the developing stages with other control methods such as neural networks which results the maximum productivity. At the end of this work, examination of the time delay of tele-controller system and experimenting according to the ISO9283 standard, specific to the accuracy of the robot, is carried out.

In this paper coupled nonlinear equations of motion of a suspended cable with time dependent tension and velocity are derived by using Hamilton’s principal. A modal analysis for a stationary sagged cable is initially carried out in order to identify the dynamic system. The natural solution is directed to compute the natural frequencies and mode shapes of the free vibration of a suspended cable. Natural frequencies and mode shapes are plotted versus a dimensionless parameter l, known as static sag character. In case of moving cable, the tension force and the rotary speed of the pullies are assumed to be sinusoidal functions. Galerkin mode summation approach is utilized to discretize the nonlinear equations of motions. Numerical simulations are carried out in the time domain. A frequency analysis is then carried out and effects of the frequency of tension force and rotary speed on the belt dynamic responses are studied.