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ABSTRACT: An efficient active queue management (AQM) controller for a class of stochastic TCP communication networks is proposed in this study. By applying the Lyapunov-Krasovskii functional approach and the linear matrix inequality (LMI) technique, a static-state-feedback controller (SSFC) capable of both achieving the desired queue size and guaranteeing asymptotic stability of the operating point is presented. A series of numerical simulations are discussed in various network environments to evaluate the proposed scheme. The simulation results show that the proposed schemes surpass other AQM schemes.
Networking, Sensing and Control, 2009. ICNSC '09. International Conference on; 04/2009
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Expert Syst. Appl. 01/2009; 36:1903-1913.
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ABSTRACT: This paper investigates the synchronization problem for FitzHugh–Nagumo (FHN) neurons in external electrical stimulations. Using the sliding mode control technique, an adaptive control law is established that guarantees synchronization even when the parameters of the master and slave FHN neurons are fully unknown. A proportional-integral switching surface is introduced to simplify the task of assigning the stability of the closed-loop error system in the sliding mode. Furthermore, the proposed synchronization scheme is then applied to a secure communication system. Computer simulations are provided to verify the effectiveness of the proposed adaptive synchronization scheme. Copyright © 2007 John Wiley & Sons, Ltd.
International Journal of Adaptive Control and Signal Processing 12/2007; 22(9):833 - 844. · 0.91 Impact Factor
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ABSTRACT: This study is concerned with the chaos synchronization problem of Rössler systems subjected to multiple time delays. Based on the sliding mode control (SMC) technique, we first propose an adaptive switching surface which does not allow for a reduction of system order, as is the case in most SMC schemes. Then both a sliding mode controller and a new sufficient condition are derived to guarantee, respectively, the global hitting of the sliding mode and stability of the equivalent error dynamics in the sliding mode. Thus, the chaos synchronization for Rössler systems with multiple time delays can surely be achieved. Moreover, the proposed scheme is then applied to the secure communication system. Numerical simulations are included to demonstrate the feasibility of the proposed scheme.
Physica Scripta 09/2007; 76(5):436. · 1.20 Impact Factor
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Proceedings of the International MultiConference of Engineers and Computer Scientists 2007, IMECS 2007, March 21-23, 2007, Hong Kong, China; 01/2007
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ABSTRACT: This paper describes the design of active queue management (AQM) controllers for a class of TCP communication networks. In TCP/IP networks, the packet-dropping probability function is considered as a control input. Therefore, a TCP AQM controller was modeled as a time-delayed system with a saturated input. The objective of the work described here was to design robust controllers capable of achieving the desired queue size and guaranteeing asymptotic stability of the operating point. To achieve this aim, we have proposed two control strategies, namely a static state feedback controller and an observer-based controller. By applying the Lyapunov–Krasovskii functional approach and the linear matrix inequality technique, control laws and delay-independent stability criteria for the AQM controllers were derived. The performance of the two control schemes was evaluated in various network scenarios via a series of numerical simulations. The simulation results confirm that the proposed schemes outperform other AQM schemes.
Information Sciences. 12/2002;
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ABSTRACT: This study is concerned with the identical synchronization problem for a class of chaotic systems. A dynamic compensator is proposed to achieve the synchronization between master and slave chaotic systems using only the accessible output variables. A sufficient condition is also proposed to ensure the global synchronization. Furthermore, the strictly positive real (SPR) restriction, which is normally required in most of the observer-based synchronization schemes, is released in our approach. Two numerical examples are included to illustrate the proposed scheme.
Chaos Solitons & Fractals 39(3):1055-1063. · 1.22 Impact Factor
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ABSTRACT: Active queue management (AQM) is a key congestion control scheme for reducing packet loss and improving network utilization in TCP/IP networks. This paper proposes a proportional–integral-derivative (PID) controller as an active queue manager for Internet routers. Due to the limitations of packet-dropping probability and the effects of propagation delays in TCP networks, the TCP AQM network was modeled as a time-delayed system with a saturated input. An improved genetic algorithm is employed to derive optimal or near optimal PID controller gains such that a performance index of integrated-absolute error (IAE) is minimized, and thereby a stable queue length, low packet loss, and high link utilization for TCP networks are guaranteed. The performance of the proposed control scheme is evaluated in various network scenarios via a series of numerical simulations.
Expert Systems with Applications.
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ABSTRACT: In this study, eight image tasks: connected component detection (CCD) with down, right, +45° and −45° directions, edge detection, shadow projection with left and right directions and point removal are analyzed. These tasks are solved using the binary input and binary output discrete-time cellular neural networks (DTCNNs) associated with suitable templates. Furthermore, the behavior of the DTCNNs can be realized using Boolean functions, and the corresponding equivalent logic circuits are derived. An 8 × 8 DTCNNs-based image-processing chip is implemented by the FPGA technology. A simulation of the chip developed for the CCD task is also presented.
Chaos, Solitons & Fractals.
