Sharif Digital Repository

In this study a synchronization method is developed to prevent the blocking arrhythmias which are caused by lack of synchronization between the two major heart pacemakers called the Sino-Atrial (SA) node and Atrio-Ventricullar (AV) node. Such pacemakers can be modeled by the Van der Pol oscillators. Feedback linearization method is used in synchronization. Since all states are not always available, they are estimated by a new observer in this research. To design the observer, first we introduce a robust observer for a unique Van der Pol oscillator. The robustness of proposed observer is obtained using gain and phase margins test. The observer variables are such that the error dynamical... 

In this paper, the synchronization of a pair of pacemaker cells as Sino-Atrial (SA) and Atrio-Ventricullar (AV) nodes have been studied and a new approach for synchronization, based on the concept of Phase Response Curve (PRC), has been proposed. The paper starts with presenting the necessary and sufficient conditions for synchronization in terms of the PRC parameters. Such conditions are time dependent and thus, the paper proceeds with deriving some sufficient conditions, which are not time dependent. The time-delay between the firing time of SA node and when it reaches the AV node is also considered. When the conditions for spontaneous synchronization are not valid, the synchronization is... 

Adsorption of Cr (VI) from aqueous solution was studied using a continuous fixed bed column which is packed with a new micro-porous composite particle developed in this study. This composite particle is composed of silica porous particle in which acrylamide is polymerized within the pore regions of the silica particles. The composite particle was supposed to maintain the mechanical properties of polyacrylamide as efficient absorbent to serve appropriately in the continuous processes. In order to enhance the adsorption capacity of the composite particle, it was modified with ethylenediamine. Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR) and...