Sharif Digital Repository

This paper describes latest results obtained on modeling, simulation and controller design of an insect-like Flapping Wing Micro Air Vehicle (FWMAV). Because of the highly nonlinear and time varying nature of insect flight and the inability to find an equilibrium point, linearization of the model without compromising the accuracy is not possible. Therefore, to address the problem of designing a controller capable of stabilizing and controlling the FWMAV around a hovering point, a metaheuristic optimization approach is proposed, based on the time averaging theorem. The results show that a controller, designed using the proposed method, is capable of stabilizing the FWMAV effectively around... 

In this paper, Artificial Neural Networks (ANN) has been used to identify the dynamics of robots used in haptic and master slave devices in order to improve transparency. In haptic and master slave devices, transparency depends on some factors such as robot's mass and inertia, gravitational forces and friction [1]. In such systems, mass and inertia of the robot has an undesirable effect on the system outputs, which should be neutralized for improved transparency. The main purpose of this paper introducting a method to neutralize the undesirable effects of mass and inertia of the robot. A recurrent multilayer perceptron (RMLP) is used in a way that the inputs and outputs of the neural network... 

Microrobots design and manufacturing has been one of interesting fields in robotics in recent years. Various legged designs have been proposed in the literature. All designs rely on friction for locomotion. In this paper the dynamic model of a planar two-legged microrobot is presented using LuGre friction model. LuGre friction model is more realistic model, reducing uncertainties of the microrobot dynamic model, providing a better prediction for both design and control applications. The proposed microrobot is driven by a piezoelectric actuator mounted between centers of two legs. One of important issues in modeling of microrobots is to determine the friction force between robot and... 

This paper presents inverse dynamics equations for a 3-UPS mechanism using virtual work principle. This mechanism has three UPS legs connecting the base to a triangular platform. By changing the orientation of leg's actuators a non-symmetric mechanism with a suitable workspace near the origin without any singularity is obtained. Direct and inverse kinematics Jacobian matrices of the mechanism are obtained by the Newton-Euler approach. Then the inverse dynamics problem is solved using the principle of virtual work, so that the force and torque of active actuators have been obtained by having external forces (force and torque) acted on the platform. Force analysis of the 3-UPS mechanism has... 

In reservoirs that have been water flooded or gas injected, it is still a significant amount of the remaining oil. Water alternative gas injection is a tertiary oil recovery method which was used for the first time in Canada for recovering remained oil in place of reservoir. The pore-scale mechanisms of this process are not fully understood yet. Such knowledge is essential for accurate modelling of reservoir. In this study various experiments on the WAG process is carried out by means of high pressure glass type micromodel instrument. The micromodel apparatus in this experiment was capable to operate at pressures up to 3500 Psi and temperatures up to 85°C which is similar to conventional... 

Relative permeability is used to describe quantitatively simultaneous transport of two or more immiscible phases through a porous medium. Accurate estimates of relative permeability curves depend on the method of estimation and are desired to obtain reliable predictions of flow behavior. To compare the accuracy of relative permeability estimation of implicit and explicit methods, primary drainage experiments of water by a sample oil fluid have been studied. The experiments performed on a horizontal glass type micromodel as a model of porous media sample under different fixed high flow rates condition to negate capillary pressure effects. The relative permeability of oil and water phases is... 

Real porous media even though seemingly homogenous and isotropic are most often nonuniform, and the nonuniformity may affect the macroscopic properties of porous media such as permeability, capillary pressure which is a result of the tortuous and circuitous nature of the flow paths in medium. In this study a glass type micromodel is considered as a porous media sample. A four parametric probability density function are used to express pore throat size, pore body size and pores length distributions which are measured using image analysis technique of porous model. The statistical models parameters are calculated by fitting the statistical model to the measured data of pore throat pore body... 

Therapeutic fragmented antibodies show a poor pharmacokinetic profile that leads to frequent high-dose administration. In the current study, for the first time, a novel proline, alanine, serine (PAS) repeat sequence called PAS#208 was designed to extend the plasma half-life of a nanosized anti-vascular endothelial growth factor-A single-domain antibody. Polyacrylamide gel electrophoresis, circular dichroism, dynamic light scattering, and electrophoretic light scattering were used to assess the physicochemical properties of the newly designed PAS sequence. The effect of PAS#208 on the biologic activity of a single-domain antibody was studied using an in vitro proliferation assay. The...