Sharif Digital Repository

In this work, we want to gain and analyze the dynamic equations of an open four bar mechanism with two flexible links and three flexible hinges. In continue, one of the applications of a 3-RRR mechanism has been mentioned and dynamic equations and angles behavior have been analyzed. The effect of hinge stiffnesses and their sequence has been investigated by using Hamilton principle. In addition, The behavior of the mechanism with flexible links has compared to the mechanism with non-flexible. At last, the results have been validated by ADAMS software.

 

This dissertation presents aeroelastic stability analysis (flutter) pertinent to the complete flexible aircraft based on analytical dynamics, structural dynamics and aerodynamics. The unified formulation is based on fundamental principles and incorporates in a natural manner both rigid body motions of the aircraft as a whole and elastic deformations of the flexible components (fuselage, wing and empennage), as well as the aerodynamic, propulsion and gravity forces. The aircraft motion is described in terms of three translations and three rotations of a reference frame attached to the undeformed fuselage, and acting as aircraft body axes, and elastic displacements of each of the flexible... 

In this study, two conventional methods for controlling flexible two-link robots based on artificial neural networks is improved. The first method is implemented by combining fuzzy logic and reinforcement learning in the form of a neural network. This method is modified in two steps. In the first step, the system feedback is changed and in the second step, the system Jacobin is used. This Jacobin can be the result of system identification. In the second method, an optimal controller is proposed for the system, which is also implemented in the form of a neural network. The performance of the neural-optimal controller is further improved by redefining the Bellman's principle of optimality.... 

The power systems’ net-load variability and uncertainty would aggravate significantly as the penetration of Renewable Energy Resources (RERs) in power systems increases. In response, power system researchers have introduced a new concept, namely flexibility, to quantitatively and systematically deal with unavoidable features of RERs. In power distribution systems as the connection point of power systems with customers, there are many opportunities for improving the flexibility level of systems. Nowadays, the emergence of prosumers has created new opportunities for distribution system operators in providing the system with different services of flexibility in distribution systems. Therefore,... 

In this study, a nonlinear aeroelastic model for an aircraft with fully flexible wings is obtained. This aeroelastic model is based on system identification and is created using the beam model for the structure and the three-dimensional panel method for aerodynamic analysis. The model intended for the structure is a nonlinear beam with exact geometry with initial deformation and rigid motion. The model intended for aerodynamics is an unsteady three-dimensional panel method for the airplane’s body, wings, and tail. The desired aeroelasticity model is a reduced-order model based on system identification using the time-domain/frequency-domain aerodynamic response under forced vibrations in the... 

Hydrodynamics of flow is affected by physical and biological interactions between flow and aquatic vegetation. This study represents the role of array distribution on lateral dispersion in emergent aquatic vegetation using two flexible and semi-rigid models. Experiments were carried out with three different arrangements, including random, staggered, and in-line. The Reynolds numbers at the stem scale ranged from 120 to 690, and the stem densities were 1% and 1.44%. Furthermore, the effects of stem flexibility and, specifically, stem resonance on lateral dispersion were examined. An image processing technique was used to measure plume width and calculate lateral dispersion. It was found that... 

Power distribution systems are experiencing restructuring owning to the increasing trend of integrating renewable energy sources as well as privatization in the network. In this regard, the dependence of power generation by renewable energy sources on meteorological characteristics would challenge the conventional procedures of operating the system. Respectively, while the expansion of renewable energy sources would facilitate supplying the demand loads locally; the issues associated with the uncertainty and variability of power generation by these units should be addressed in future operational schemes of distribution systems. This condition has resulted in the development of the... 

The flexible magnetic robot is used for minimally invasive surgeries where there is a complex environment. Precise control of the position of the end of the robot and quick adaptation of the robot to uncertainties are among the most important challenges in this field, where the controller is responsible for compensating the error and controlling the position of the end of the robot. Now, is it possible to create a kind of memory in the system that when faced with the same or similar errors in the same situations or close to previous errors, the system uses its past and compensates the error? The importance of this work is that the response speed of the system is increased and the system can...