Sharif Digital Repository

One of the most common problems encountered in multivariable systems is the interactions between the system inputs and outputs. Interaction causes difficulties in control of these systems. Hence reduction of interaction in multivariable systems is an important design objective. One way to do this is to employ a pre-compensator in the open loop systems. Several approaches with different design methods and optimization criterions have been proposed thus far. In this study the problem of interaction reduction for a square stable system is considered and a pre-compensator matrix is designed which reduces interactions in the interacting multivariable system.In this case the purpose is to use... 

Monitoring and control of gas transmission networks are very challenging and important, this is due to the fact that interactions between various elements in the transmission network severely affect network’s overall performance. This makes it crucial for the monitoring and control systems to take into account the topology of the network, in their decision making and control scenario’s. On the other hand, in the event of any abnormality in the network behavior, , in order to accurately and quickly detect the cause of the abnormal conditions, there is a need for rapid and effective analysis of the network based on the measurements made therein and to identify the key and effective situations... 

Order reduction is a very important issue in Control Theory. A growing need for order reduction models in different fields such as simulation, identification, and design of control system shows this significance. Actually, a high-order system makes a great deal of complexity in designing hardware of control system, debugging, and implementation. Till nowadays, many repetitive as well as nonrepetitive methods with various criteria have been introduced to find low-order models. In this research, order reduction of linear time invariant system models is analyzed. The selected criterion for measuring error between original system and reduced order system is the norm of H1 because it is not only... 

Monitoring of the water transmission networks is an essential factor to regard efficient, safe and economical strategic considerations. Several parameters (fluid pressure, fluid flow and fluid temperature in some cases) are measured to monitor the water transmission networks. The number and location of these measurements in deferent positions affect the cost and quality of the network states monitoring. It is obvious that measuring the all parameters and states of the network is not cost-effective even when it is possible. The conventional sensor-location methods have been developed based on the pressure variation stemmed from a leakage in the network. This study proposes a new procedure to... 

Inthis thesis, we provide a reduced multiple linear approximationfornonlinear systems. This approximationis a weighted summation of reduced order models thatapproximates the states or output(s) of the nonlinear system. It can be used inreal-time control instead of high-ordernonlinear models in order toreduce thecomputational cost. The reduction of computation cost is claimed qualitatively, based on the linearity of the approximation and its less order compared to the original model. To form amultiple modelapproximation eachlinearmodelis obtained from linearization atanoperating point. Then,each model is reduced byalinearreduction method. We used truncation and balanced residualization... 

Most of the robust or optimal controllers can produce extremely fragile controllers [1], in the sense that vanishingly small perturbations of the coefficients of the designed controller destabilize the closed-loop control system. Modern control methods, including robust control, lead to high order controllers.Often times a reduced order controller is implemented. As a result, need for low order control design reducing controller’s ensitivity is tangible. Based on studies carried out, properties of normal matrices can be employed to define a fragility measure. In this thesis, a new convex criterion measuring controller fragility is defined. Then, a more resilient reduced order controller can... 

Some systems exhibit probabilistic and nondeterministic behavior. This behavior arises, for example, due to the use of randomized algorithms or presence of the unreliable components. Probabilistic Activity Network (PAN) is a flexible model for describing such systems. Every PAN is convertible to a Markov decision process. Up to now, there is no model checker which can operate directly on this model. In addition state space explosion arises as an important problem in model checking of real systems. We have developed a software tool called SPTMAN, for model checking of PAN. In this dissertation we are going to present a way for applying partial order reduction on PAN and then we will introduce...