ahmad samiee

This paper addresses the application of using pneumatic force actuators at the hips of a five-link robotic system to provide a controllable input torque. The goal of this research is to provide a base to build upon to eventually produce an ” active” biped walking robot that utilizes the benefits of the passive walking cycle. A reduced-order mathematical model of the system consisting of the pneumatic proportional valve and actuators is utilized in designing the force controller. The model takes into account tube links, valve friction, piston friction, and valve mechanics. The five-link robot is also modeled, including moments of inertia, masses, and centers of mass to design the trajectory controller. The mathematical models provide the equations necessary to develop the nonlinear control laws based on Sliding Mode Control Theory for both the force and trajectory controller. The controllers receive input signals from both pressure and position sensors located at the hips and position sensors at the knees. These signals are then converted into digital signals and processed by the computer using numerical analysis to obtain ethical values. Once the signals are input into the controllers, the experimental results of the actual system track the desired force and position trajectories defined for each controller within desired limits.

In this study, the effect of heat transfers on lift and drag coefficients of two symmetric and camber airfoils with plunging motion in laminar flow is numerically investigated. The compressible Navier–Stokes equations are discretized using a finite volume method and they are solved by PIMPLE algorithm. In this simulation, fluid dynamic viscosity and thermal conductivity are considered to be variable. Also dynamic mesh method is used for oscillating motion. The results show that, by reducing the airfoil surface temperature less than the free flow temperature, lift to drag ratio increases. Moreover, influence of heat transfer on vortexes pattern at airfoils trailing edge and therefore its impact on the aerodynamic coefficients are investigated.

Research activities are carried out at two academic and national levels, aimed at thesmall community of academicians and wide public readers respectively. This articledeals with planning for research activities at the national level. It concerns withquestions such as reasons and uses of planning as well as the aims of suchresearches. To this end, it is necessary to creatively use previous studies andexperiences. In particular, the article underlines the necessity to examine theactivities of the modernists during the Constitutional Revolution and the intellectualsactive in the years following September 1941 at national level, and the convergenceof the French philosophers and Encyclopedists of the 18th century, and the Russianthinkers of the 19th century at global level, as well as the contemporary profoundsocial and political changes and the increasing development of knowledge andtechnology.