Sharif Digital Repository

Traditionally, chemical Process design is focused on the selection of technologies and optimization based on economic consideration .In the 1970’s because of the global energy crisis, other consideration consider with economic goals .in this study we are eager to provide design procedures and guidance for optimizing chemical processes simultaneously based on economic and environmental aspects .this optimization is applied to production maleic anhydride(MA) from n-butane feedstock .an optimization algorithm based on the genetic algorithm with four decision variables(recycle flow ratio ,air to feed ratio ,solvent flow and reactor temperature ).for including dynamic objective in optimization... 

The application of Stochastic Differential Equations in branches like nonlinear control,robatic systems, financial mathematics and etc. has grown impressively nowadays. In this thesis, we are going to introduce this equations and study their stability. First, we will present methods to check the stability of nonlinear systems dx(t) = f(x(t); t)dt using Lyapunov’s theorem.Then we will study stability of autonomous systems using it’s results. In the case of instability, we will study the possibility of stabilizing the stochastic equations dx(t) = Ax(t)dt + Σn i=1 Bix(t)dWi(t) by using Brownian motions and these methods. In the end, we will study the stabilizablity conditions of instable... 

Selecting an appropriate control structure is an important subject in the design of control systems. Distillation column is one of the most popular and widely used unit operations in industry which complete understanding of its operability and controllability is one of the most important issues in the process control engineering. The present work studies the method of Output Controllability Index for nonlinear systems and compares it with Relative Gain Array and Condition Number. By using this index, the extent of intrinsic controllability of a process can be identified quantitatively in the absence of any controller. Also, the controllability of the process can be stated numerically or... 

In this study, the attitude control of an under-actuated satellite has been investigated. The investigated satellite uses reaction wheels for attitude control. For having full controllability of a satellite attitude, at least three reaction wheels are required. However, due to the high failure rate of reaction wheels, in this study assumed the satellite has two perpendicular reaction wheels, which causes the satellite to be under-actuated. The path planning method is used for controlling the satellite, which is an offline method. In the beginning, tries to define the control input of the satellite in term of limited parameters with different methods. In this regard, the control input is... 

Tipping points occur in diverse systems in various disciplines such as ecology, climate science, economy, sociology, and engineering. Critical thresholds in system parameters or state variables at which a tiny perturbation can lead to a qualitative change in the system exist in many subsystems in complex systems. These thresholds are called tipping points, and these subsystems are called tipping elements. Additionally, many systems with tipping points can be modeled as networks of coupled multistable subsystems. Domino-like tippings are called tipping cascades. Considering that these tipping cascades are primarily unprecedented, it is essential to study the dynamics and control of these...