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    An efficient synchronization circuit in multi-rate SDH networks

    , Article Arabian Journal for Science and Engineering ; Volume 39, Issue 4 , April , 2014 , Pages 3101-3109 ; ISSN: 13198025 Zare, M ; Hessabi, S ; Goudarzi, M ; Sharif University of Technology
    Abstract
    Single-rate synchronous digital hierarchy (SDH) networks contain one master block and several slave blocks and the slaves will synchronize themselves by the master clock frequency. However, the clock frequencies of master and slaves are different in multi-rate SDH networks and hence, the slaves require a synchronization circuit to match their clock frequencies with the master clock frequency. This research presents an efficient synchronization circuit for such networks. The proposed circuit occupies smaller area than the prior circuit and requires no clock alignment for its implementation. The circuit constraints are described and the maximum clock frequencies of master and slaves are... 

    Comments on " Synchronization and anti-synchronization of new uncertain fractional-order modified unified chaotic systems via novel active pinning control" [Commun Nonlinear Sci Numer Simulat 2010;15:3754-3762]

    , Article Communications in Nonlinear Science and Numerical Simulation ; Volume 16, Issue 6 , June , 2011 , Pages 2656-2657 ; 10075704 (ISSN) Asheghan, M. M ; Beheshti, M. T. H ; Tavazoei, M. S ; Sharif University of Technology
    2011
    Abstract
    In this note some points to paper [L. Pan, W. Zhou, J. Fang, D. Li, Synchronization and anti-synchronization of new uncertain fractional-order modified unified chaotic systems via novel active pinning control, Commun Nonlinear Sci Numer Simulat 2010;15:3754-3762] are presented. Hereby, we illustrate that the way that authors in [1] treat with fractional version of Lyapunov stability theorem suffers lack of a correct justification  

    Comment on: "Synchronization of two chaotic nonlinear gyros using active control" [Phys. Lett. A 343 (2005) 153]

    , Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 372, Issue 14 , 2008 , Pages 2539-2540 ; 03759601 (ISSN) Salarieh, H ; Sharif University of Technology
    Elsevier  2008
    Abstract
    A modification to the control law presented in [Y. Lei, W. Xu, H. Zheng, Synchronization of two chaotic nonlinear gyros using active control, Phys. Lett. A 343 (2005) 153] is proposed. © 2007 Elsevier B.V. All rights reserved  

    The contrastive study of identical and generalized synchronization

    , Article International Conference on Control, Automation and Systems, ICCAS 2007, Seoul, 17 October 2007 through 20 October 2007 ; December , 2007 , Pages 1573-1576 ; 8995003871 (ISBN); 9788995003879 (ISBN) Alibeaki, S ; Haeri, M ; Sharif University of Technology
    2007
    Abstract
    The main purpose of this study is to compare identical synchronization and linear generalized synchronization from various points of views including synchronization error variance, convergence time, control effort variance, maximum and minimum values of the control signal. The nonlinear control is used in the both synchronizations. The results of our study show that the identical synchronization is not the optimal one from the mentioned criteria points of view. © ICROS  

    Impulsive synchronization of Chen's hyperchaotic system

    , Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 356, Issue 3 , 2006 , Pages 226-230 ; 03759601 (ISSN) Haeri, M ; Dehghani, M ; Sharif University of Technology
    Elsevier  2006
    Abstract
    In this Letter the impulsive synchronization of the Chen's hyperchaotic systems is discussed. Some new and sufficient conditions on varying impulsive distance are established in order to guarantee the synchronizabillity of the systems using the synchronization method. In particular, some simple conditions are derived in synchronizing the systems by equal impulsive distances. Two illustrative examples are provided to show the feasibility and the effectiveness of the proposed method. The boundaries of the stable regions are also estimated. © 2006 Elsevier B.V. All rights reserved  

    Multivariate Synchronization Analysis of Brain Electroencephalography Signals: A Review of Two Methods

    , Article Cognitive Computation ; Volume 7, Issue 1 , February , 2013 , Pages 3-10 ; 18669956 (ISSN) Jalili, M ; Sharif University of Technology
    Springer New York LLC  2013
    Abstract
    Temporal synchronization of neuronal activity plays an important role in various brain functions such as binding, cognition, information processing, and computation. Patients suffering from disorders such as Alzheimer’s disease or schizophrenia show abnormality in the synchronization patterns. Electroencephalography (EEG) is a cheap, non-invasive, and easy-to-use method with fine temporal resolution. Modern multichannel EEG data are increasingly being used in brain studies. Traditional approaches for identifying synchronous activity in EEG are through univariate techniques such as power spectral density or bivariate techniques such as coherence. In this paper, we review two methods for... 

    Generalized synchronization of non-identical chaotic systems with minimum control effort

    , Article 2008 International Conference on Control, Automation and Systems, ICCAS 2008, Seoul, 14 October 2008 through 17 October 2008 ; 2008 , Pages 2330-2333 ; 9788995003893 (ISBN) Alibeiki, E ; Haeri, M ; Sharif University of Technology
    2008
    Abstract
    In synchronization of identical chaotic systems, the control cost would be optimal in the sense that it would be zero when the synchronization is occurred. Based on this idea, in synchronization of non-identical chaotic systems, we find a signal function added to states of the derive system so that it makes the dynamics of the drive system translated into dynamics of the response system. After synchronizing two systems using this function, states of the response system will be synchronized with the equivalent states and the control cost will be optimal similar to those in the identical synchronization. © ICROS  

    Prediction of chaos in non-salient permanent-magnet synchronous machines

    , Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 377, Issue 1-2 , December , 2012 , Pages 73-79 ; 03759601 (ISSN) Rasoolzadeh, A ; Tavazoei, M. S ; Sharif University of Technology
    2012
    Abstract
    This Letter tries to find the area in parameter space of a non-salient Permanent-Magnet Synchronous Machine (PMSM) in which chaos can occur. This area is briefly named as chaotic area. The predicted chaotic area is obtained by checking some conditions which are necessary for existence of chaos in a dynamical system. In this Letter, it is assumed that this machine is in the generator mode, and its model is based on direct and quadrature axis of stator voltages and currents. The information of the predicted area is used in non-chaotic maximum power control of torque in the machine  

    Chaos synchronization in noisy environment using nonlinear filtering and sliding mode control

    , Article Chaos, Solitons and Fractals ; Volume 36, Issue 5 , 2008 , Pages 1295-1304 ; 09600779 (ISSN) Behzad, M ; Salarieh, H ; Alasty, A ; Sharif University of Technology
    2008
    Abstract
    This paper presents an algorithm for synchronizing two different chaotic systems, using a combination of the extended Kalman filter and the sliding mode controller. It is assumed that the drive chaotic system has a random excitation with a stochastically chaotic behavior. Two different cases are considered in this study. At first it is assumed that all state variables of the drive system are available, i.e. complete state measurement, and a sliding mode controller is designed for synchronization. For the second case, it is assumed that the output of the drive system does not contain the whole state variables of the drive system, and it is also affected by some random noise. By combination of... 

    Comparison between different synchronization methods of identical chaotic systems

    , Article Chaos, Solitons and Fractals ; Volume 29, Issue 4 , 2006 , Pages 1002-1022 ; 09600779 (ISSN) Haeri, M ; Khademian, B ; Sharif University of Technology
    2006
    Abstract
    This paper studies and compares three nonadaptive (bidirectional, unidirectional, and sliding mode) and two adaptive (active control and backstepping) synchronization methods on the synchronizing of four pairs of identical chaotic systems (Chua's circuit, Rössler system, Lorenz system, and Lü system). Results from computer simulations are presented in order to illustrate the effectiveness of the methods and to compare them based on different criteria. © 2005 Elsevier Ltd. All rights reserved  

    Robust stability of impulsive synchronization in hyperchaotic systems

    , Article Communications in Nonlinear Science and Numerical Simulation ; Volume 14, Issue 3 , 2009 , Pages 880-891 ; 10075704 (ISSN) Haeri, M ; Dehghani, M ; Sharif University of Technology
    2009
    Abstract
    In this paper the impulsive synchronization of general continuous chaotic and hyperchaotic systems is investigated. The robust stability of the synchronization method is examined in the presence of uncertainties both on linear and nonlinear parts of the system dynamics and the channel noise. Conditions on the impulse distances are derived for different cases. Numerical simulations are presented to show the effectiveness of the method. © 2007 Elsevier B.V. All rights reserved  

    Chaos synchronization of nonlinear gyros in presence of stochastic excitation via sliding mode control

    , Article Journal of Sound and Vibration ; Volume 313, Issue 3-5 , 2008 , Pages 760-771 ; 0022460X (ISSN) Salarieh, H ; Alasty, A ; Sharif University of Technology
    2008
    Abstract
    In this paper the problem of synchronization between two chaotic gyros with stochastic base excitation, based on the mater-slave scheme, is studied. The stochastic excitation is modeled by applying a Gaussian white noise to the deterministic model of gyro. The white noise is derived from the Wiener process, so the resulted system is a stochastic differential equation and is modeled by an Ito differential form. Using a modified sliding mode control a Markov synchronizing control law is designed and the convergence of error states to the sliding surface in the mean square norm is analytically proved. Simulation results show the high performance of the proposed controller in stochastic chaos... 

    Application of static synchronous series compensator to damp sub-synchronous resonance

    , Article 2006 International Conference on Power Electronics, Drives and Energy Systems, PEDES '06, New Delhi, 12 December 2006 through 15 December 2006 ; 2006 ; 078039772X (ISBN); 9780780397729 (ISBN) Barati, H ; Lashkar Ara, A ; Ehsan, M ; Fotuhi Firuzabad, M ; Bathaee, M. T ; Sharif University of Technology
    2006
    Abstract
    In this paper, a Static Synchronous Series Compensator (SSSC) is used to avoid torsional mode instability in a series compensated transmission system. The power system used in this study is the IEEE first benchmark model for Sub-Synchronous Resonance (SSR) analysis. Simulation results in time domain using PSCAD/EMTDC presented and discussed. ©2006 IEEE  

    On the fractional-order extended Kalman filter and its application to chaotic cryptography in noisy environment

    , Article Applied Mathematical Modelling ; Vol. 38, issue. 3 , 2014 , pp. 961-973 ; ISSN: 0307904X Sadeghian, H ; Salarieh, H ; Alasty, A ; Meghdari, A ; Sharif University of Technology
    Abstract
    In this paper via a novel method of discretized continuous-time Kalman filter, the problem of synchronization and cryptography in fractional-order systems has been investigated in presence of noisy environment for process and output signals. The fractional-order Kalman filter equation, applicable for linear systems, and its extension called the extended Kalman filter, which can be used for nonlinear systems, are derived. The result is utilized for chaos synchronization with the aim of cryptography while the transmitter system is fractional-order, and both the transmitter and transmission channel are noisy. The fractional-order stochastic chaotic Chen system is then presented to apply the... 

    Robust synchronization of chaotic systems using active sliding mode control with minimum control effort

    , Article International Journal of Modern Physics B ; Volume 25, Issue 17 , July , 2011 , Pages 2271-2288 ; 02179792 (ISSN) Naseh, M. R ; Haeri, M ; Sharif University of Technology
    2011
    Abstract
    oActive sliding mode control is one of the effective methods to synchronize chaotic systems in the presence of uncertainties. Use of the method, however, requires decision making on how to choose the control parameters for a specific performance. In this paper we propose an algorithm to determine the best control parameters for which the minimum control efforts are required to synchronize two identical or non-identical chaotic systems. We have also determined the maximum range of the uncertainties on which the selected control parameters to work properly. The effectiveness of the proposed method has been verified through numerical simulations  

    Robust synchronization of perturbed Chen's fractional-order chaotic systems

    , Article Communications in Nonlinear Science and Numerical Simulation ; Volume 16, Issue 2 , 2011 , Pages 1044-1051 ; 10075704 (ISSN) Asheghan, M. M ; Hamidi Beheshti, M. T ; Tavazoei, M. S ; Sharif University of Technology
    Abstract
    In this paper, based on a stability theorem proved for linear fractional-order systems, a scheme for robust synchronization of two perturbed fractional-order Chen systems is proposed. In the proposed scheme, both master and slave systems are considered to be involved with external disturbances having unknown values. It is analytically shown that any set of bounded external disturbances can be damped by the proposed method, where synchronization error will be forced and then kept inside a ball around the origin. Since during the design procedure the radius of this ball could be easily chosen by the designer, the synchronization can be done with any desired accuracy. The proposed method can be... 

    Modified impulsive synchronization of hyperchaotic systems

    , Article Communications in Nonlinear Science and Numerical Simulation ; Volume 15, Issue 3 , 2010 , Pages 728-740 ; 10075704 (ISSN) Haeri, M ; Dehghani, M ; Sharif University of Technology
    2010
    Abstract
    In an original impulsive synchronization only instantaneous errors are used to determine the impulsive inputs. To improve the synchronization performance, addition of an integral term of the errors is proposed here. In comparison with the original form, the proposed modification increases the impulse distances which leads to reduction in the control cost as the most important characteristic of the impulsive synchronization technique. It can also decrease the error magnitude in the presence of noise. Sufficient conditions are presented through four theorems for different situations (nominal, uncertain, noisy, and noisy uncertain cases) under which stability of the error dynamics is... 

    A loss minimization control strategy for direct torque controlled interior permanent magnet synchronous motors

    , Article Journal of Power Electronics ; Volume 9, Issue 6 , 2009 , Pages 940-948 ; 15982092 (ISSN) Siahbalaee, J ; Vaez Zadeh, S ; Tahami, F ; Sharif University of Technology
    2009
    Abstract
    The main objective of this a paper is to improve the efficiency of permanent magnet synchronous motors (PMSMs) by using an improved direct torque control (DTC) strategy. The basic idea behind the proposed strategy is to predict the impact of a small change in the stator flux amplitude at each sampling period to decrease electrical loss before the change is applied. Accordingly, at every sampling time, a voltage vector is predicted and applied to the machine to fulfill the flux change. The motor drive simulations confirm a significant improvement in efficiency as well as a very fast and smooth response under the proposed strategy  

    A secure self-synchronized stream cipher

    , Article Computer Journal ; Volume 61, Issue 8 , August , 2018 , Pages 1182-1201 ; 00104620 (ISSN) Daneshgar, A ; Mohebbipoor, F ; Sharif University of Technology
    Oxford University Press  2018
    Abstract
    We follow two main objectives in this article. On the one hand, we introduce a security model called LORBACPA+ for self-synchronized stream ciphers which is stronger than the blockwise LOR-IND-CPA, where we show that standard constructions as delayed CBC or similar existing self-synchronized modes of operation are not secure in this stronger model. Then, on the other hand, following contributions of Millérioux et al., we introduce a new self-synchronized stream cipher and prove its security in LORBACPA+ model. © The British Computer Society 2018. All rights reserved  

    Adaptive synchronization of two different chaotic systems with time varying unknown parameters

    , Article Chaos, Solitons and Fractals ; Volume 37, Issue 1 , 2008 , Pages 125-136 ; 09600779 (ISSN) Salarieh, H ; Shahrokhi, M ; Sharif University of Technology
    2008
    Abstract
    In this paper a nonlinear control method based on Lyapunov stability theorem is proposed to design an adaptive controller for synchronizing two different chaotic systems. It is assumed that the unknown parameters of the drive and the response chaotic systems are time varying. It is shown that the proposed scheme can identify the system parameters if the system parameters are time invariant and the richness conditions is satisfied. To demonstrate the effectiveness of the proposed technique it has been applied to Lorenz-Chen dynamic systems, as drive-response systems. Simulation results indicate that the proposed adaptive controller has a high performance in synchronizing two chaotic systems....