Sharif Digital Repository

In this work performances of adaptive backstepping controller (BSC) and globally linearizing controller (GLC) are compared for pH control. First, based on the system full order model a GLC has been designed and it has been shown that this controller is identical to BSC proposed in the literature. Next in order to avoid state estimator design, BSC and GLC are designed based on pH reduced order model and their identities have been established. Through computer simulations, it has been shown that the performance of non-adaptive GLC designed based on reduced order model is better than that of adaptive BSC designed based on pH full order model which requires state measurement for implementation.... 

In this paper, an output tracking controller is proposed for cooperative transport of a gripped load by a team of quadrotors. The proposed control law requires the measurement of only four state variables: position and yaw angle of the system. Moreover, the controller provides rejection of step and ramp external force disturbances. In addition, the control basis vectors derived via optimization facilitate the real-time determination of quadrotors' control inputs. Numerical simulations show the effectiveness of the proposed control scheme and its superiority over formerly designed controllers for such systems. © 2019 Sharif University of Technology. All rights reserved  

As radar signals propagate above the ocean surface to determine the trajectory of a target, the signals that are reflected directly from the target arrive at the receiver along with indirect signals reflected from the ocean surface. These unwanted signals must be properly filtered; otherwise, their interference may mislead the signal receiver and significantly degrade the tracking performance of the radar. To this end, we propose a low-elevation target tracking mechanism considering the specular and diffuse reflection effects of multipath propagation over the ocean surface simultaneously. The proposed mechanism consists of a state-space model and a particle filtering algorithm and promises... 

Railway managers have a strong economic incentive to minimize track maintenance costs, while maintaining safety standards and providing adequate service levels to train operators. The objective of this study is to apply a procedure for making optimal maintenance decisions in Iranian Railways. This study consists of two parts. First, a cumulative damage model, based on a Markov process, is applied to model the deterioration of the track. For this reason, tracks are categorized into six classes, so that those tracks with similar traffic loads and geographical location are collected into one class. The track survey data from 215 blocks (4,228 km) of the ten divisions of the Iranian Railway...