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Aghababa M.P.,Urmia University of Technology
Nonlinear Dynamics | Year: 2013

This paper concerns the problem of robust control of uncertain fractional-order nonlinear complex systems. After establishing a simple linear sliding surface, the sliding mode theory is used to derive a novel robust fractional control law for ensuring the existence of the sliding motion in finite time. We use a nonsmooth positive definitive function to prove the stability of the controlled system based on the fractional version of the Lyapunov stability theorem. In order to avoid the chattering, which is inherent in conventional sliding mode controllers, we transfer the sign function of the control input into the first derivative of the control signal. The proposed sliding mode approach is also applied for control of a class of nonlinear fractional-order systems via a single control input. Simulation results indicate that the proposed fractional variable structure controller works well for stabilization of hyperchaotic and chaotic complex fractional-order nonlinear systems. Moreover, it is revealed that the control inputs are free of chattering and practical. © 2013 Springer Science+Business Media Dordrecht. Source

Aghababa M.P.,Urmia University of Technology
Nonlinear Dynamics | Year: 2015

Chaos control and synchronization of second-order nonautonomous fractional complex chaotic systems are discussed in this paper. A novel fractional nonsingular terminal sliding surface which is suitable for second-order fractional systems is proposed. It is proved that once the state trajectories of the system reach to the proposed sliding surface, they will be converged to the origin within a given finite time. After establishing the desired terminal sliding surface, a novel robust single sliding mode control law is introduced to force the system trajectories to reach the terminal sliding surface over a finite time. The stability and robustness of the proposed method are proved using the latest version of the fractional Lyapunov stability theorem. The proposed method is implemented for synchronization of two uncertain different fractional chaotic systems to confirm the theoretical results. Moreover, the fractional-order gyro system is stabilized using the proposed fractional sliding mode control scheme. It is worth noticing that the proposed fractional sliding mode approach is still a general control method and can be applied for control of second- order uncertain nonautonomous/autonomous fractional systems. © 2014, Springer Science+Business Media Dordrecht. Source

Aghababa M.P.,Urmia University of Technology
ISA Transactions | Year: 2013

The problem of active control of vibration structures has attracted much attention over the past decades. A general description of the control problem of vibration systems is to design an active controller to suppress the vibrations of the system induced by external disturbances such as an earthquake. In this paper, a novel fractional-order sliding mode control is introduced to attenuate the vibrations of structures with uncertainties and disturbances. After establishing a stable fractional sliding surface, a sliding mode control law is proposed. Then, the global asymptotic stability of the closed-loop system is analytically proved using fractional Lyapunov stability theorem. Finally, the robustness and applicability of the technique are verified using two examples, including a three degree of freedom structure and a two-story shear building. © 2013 ISA.Published by Elsevier Ltd. All rights reserved. Source

Sadrzadeh A.,Urmia University of Technology
Computers and Industrial Engineering | Year: 2012

The paper presents a genetic algorithm-based meta-heuristic to solve the facility layout problem (FLP) in a manufacturing system, where the material flow pattern of the multi-line layout is considered with the multi-products. The matrix encoding technique has been used for the chromosomes under the objective of minimizing the total material handling cost. The proposed algorithm produces a table with the descending order of the data corresponding to the input values of the flow and cost data. The generated table is used to create a schematic representation of the facilities, which in turn is utilized to heuristically generate the initial population of the chromosomes and to handle the heuristic crossover and mutation operators. The efficiency of the proposed algorithm has been proved through solving the two examples with the total cost less than the other genetic algorithms, CRAFT algorithm, and entropy-based algorithm. © 2011 Elsevier Ltd. All rights reserved. Source

Aghababa M.P.,Urmia University of Technology
Chinese Physics B | Year: 2012

The present paper investigates the existence of chaos in a non-autonomous fractional-order micro-electromechanical resonator system (FOMEMRS). Using the maximal Lyapunov exponent criterion, we show that the FOMEMRS exhibits chaos. Strange attractors of the system are plotted to validate its chaotic behavior. Afterward, a novel fractional finite-time controller is introduced to suppress the chaos of the FOMEMRS with model uncertainties and external disturbances in a given finite time. Using the latest version of the fractional Lyapunov theory, the finite time stability and robustness of the proposed scheme are proved. Finally, we present some computer simulations to illustrate the usefulness and applicability of the proposed method. © 2012 Chinese Physical Society and IOP Publishing Ltd. Source

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