Sharif Digital Repository

In this work dynamic behavior of a two body TSS with main satellite as rigid body is studied and effects of tether elasticity and tension on the satellite dynamic are indicated in station keeping phase and circular orbit. Also a simplified modeling is introduced which could be used in nonlinear controller design. Lagrange and extended Lagrange method is used to derive equations of motion. It is shown that longitudinal vibration of tether has small effect on satellite attitude and angular velocity and because of high frequency it can be decoupled from satellite dynamic. In the simplified model, orbital motion is decoupled from equations of TSS and main satellite dynamic. Effect of decoupling... 

Given the optimum design importance of parallel mechanisms, characteristics such as degree of freedom, decoupled and isotropic in structural synthesis of these mechanisms are considered. Also, due to less attention to the development of 5-DoF parallel manipulators, in this research, the improvement of this types of mechanisms is considered. In this research effort to design 5-DoF cartesian, decoupled and isotropic parallel manipulators leads to represent four numbers of this type of mechanisms with 3T2R and 2T3R degrees of freedom. Represented PMs verified with linear transformation theory. Morever by using Jacobian, they more analyzed for their decoupled and isotropic specifications in... 

Design of complex systems requires different challenges to be met simultaneously. Yet the current methods lack a sound theoretic framework and thus designers normally rely on heuristic or empirical methods; based on available experiences. Such approaches to the system design entail both technical and business risks and subsequently increase the probability of long-term problems. In this research, along with the theoretical framework of the systems design concepts, we discuss number of important models. The main concentration of the work, however, is to; somehow, correlate Axiomatic Design Matrix (ADM) with Design Structure Matrix (DSM). Here we exploit mathematical model based on sets and by... 

Many processes in the real world are multiple-input multiple-output (MIMO) systems. There are often some interactions between the inputs and outputs. In the other words, every input affects on several outputs, and every output is affected by several inputs. In order to control of these systems, we usually desire to decouple the loops into multiple non-interacting SISO systems after proper pairing of manipulated and controlled variables. Loop interactions can destabilize a control system, so tuning controllers in an interacting MIMO system can be difficult. Decoupling problem has been discussed in the two domains: linear control and nonlinear control. However, both of them need an exact model... 

With the increase in the number of regulatory agencies and the proliferation of the idea of regulatory state since the second half of the 20th century, regulators have become one of the important pillars of governance systems. In Iran, the communication market can be considered one of the leading markets in having a modern regulatory body. This thesis deals with the evaluation and analysis of the situation of Iran's communications regulator. In the descriptive layer, relying on regulatory governance literature, we examine Iran's communications regulator from the perspective of institutional indicators of independence, accountability, and tools. We argue that the characteristics of regulators...