Application Of Synchronization Research Articles

High-precision nonlocal temporal correlation identification of entangled photon pairs for quantum clock synchronization.

High-precision nonlocal temporal correlation identification in entangled photon pairs is critical to measure the time offset between remote independent time scales for many quantum information applications. The first nonlocal correlation identification was reported in 2009, which extracts the time offset via the algorithm of iterative fast Fourier transformations and their inverse. The best identification resolution is restricted by the peak identification threshold of the algorithm, and thus the time offset calculation precision is limited. In this paper, an improvement for the identification is presented both in resolution and precision via a modified algorithm of direct cross correlation extraction. A flexible resolution down to 1 ps is realized, which is only dependent on the least significant bit resolution of the time-tagging device. The attainable precision is shown to be mainly determined by the inherent timing jitter of single photon detectors, the acquired pair rate, and acquisition time, and a sub-picosecond precision (0.72 ps) has been achieved at an acquisition time of 4.5 s. This high-precision nonlocal measurement realization provides a solid foundation for the field applications of entanglement-based quantum clock synchronization, ranging, and communications.

Application of fuzzy synchronization in the NLOS UV communication system

Application of fuzzy synchronization in the NLOS UV communication system

Linear Kalman Filter-Based Grid Synchronization Technique: An Alternative Implementation

Grid synchronization techniques play a significant role in integrating renewable energy sources to the electric power grid. In this context, estimating the phase and frequency of the grid voltage signal is an interesting problem. Out of various techniques available in the literature, linear Kalman filter (LKF) is one of the most popular one. In this article, we propose an alternative implementation of the LKF for grid synchronization application. The proposed implementation uses a linear parametric model of the grid voltage signal including dc offset. It does not involve any quadrature signal generation, rather it works by estimating the phase angle. This helps to estimate the unknown grid frequency directly from the phase angle. This clearly differentiates the proposed alternative implementation with respect to the existing implementations. Performance improvement by the proposed technique is verified extensively through comparative numerical simulation and experimental studies. Comparative results demonstrate the suitability of the proposed technique with respect to other state-of-the-art techniques namely second-order generalized integrator phase-locked loop and enhanced phase-locked loop.

Dislocated hybrid synchronization via. tracking control & parameter estimation methods with application

ABSTRACT In this article the dislocated hybrid synchronization between chaotic systems of different structures viz. real integer order and complex fractional order have been performed using two control methods viz. tracking control method and parameter estimation adaptive method. Illustrative example of the application of synchronization in secure communication has been performed. Numerical simulations have been performed using MATLAB which verify the efficacy of both the methods and help compare results.

Impulsive Synchronization of Derivative Coupled Neural Networks With Cluster-Tree Topology

This article is devoted to discussing the exponential synchronization for a kind of delay derivative coupled neural networks with stochastic disturbance and multiple time-varying delays. To simulate more practical situations and widen the synchronization application fields in network science, the coupled neural networks with cluster-tree topology structure is studied by applying a novel impulsive pinning control strategy, which skillfully considered the neural networks in current cluster that directly linked to the neural networks in other clusters. Since the existence of delayed impulses, the general comparison principle for normal impulsive differential equations is efficiently extended. In view of the concept of average impulsive interval, the parameters classification discussion method and the mathematical induction method, some judgement conditions for achievement of the cluster synchronization on derivative coupled neural networks are derived. Additionally, the exponential convergence velocity of the derivative coupled neural networks is accurately estimated. Finally, numerical examples are presented to demonstrate the effectiveness of the control strategy and the theoretical results.

Fundamental Concepts of Synchronization

Objects with rhythms naturally synchronize. Synchronization is the coordination of events in order to run the system uniformly. Yet the phenomenon went entirely undocumented until 1665. Since the pioneering description of synchronization by Huygens, the phenomenon has been studied by various researchers in an interdisciplinary manner. Many researchers have contributed to the development of synchronization theory proving that synchronization occurs in coupled non-linear dissipative oscillators. Such oscillators range from mechanical clocks and population dynamics to human heart and neural networks. This article aims to explain the basic principles of synchronization theory. The history and applications of synchronization are discussed in real-world scenarios. We address different types of synchronization with a detailed discussion on the simplest type of synchronization. The phenomenon of synchronization applies to oscillations of different forms—periodic, noisy, and chaotic in nature. Here, we specifically discuss the oscillators which can hold synchronization. In particular, we provide an overview of self-sustained periodic and chaotic oscillators with a detailed description of different forms of these oscillators in phase space. Further, a summary of further research challenges has also been given for the future development of advanced applications based on natural synchronization phenomenon.

Recent advances in phase-locked loop based synchronization methods for inverter-based renewable energy sources

<p>Recently, researchers have shown an increased interest in renewable energy sources (RESs) to improve power quality, reliability and stability of the power system. However, RESs require proper control strategies to ride through grid disturbances and stay connected to the main grid for the stability contribution. Moreover, the control of them relies mainly on the synchronization algorithms to precisely detect the voltage phase angle, magnitude and frequency. Throughout the years, various synchronization schemes have been introduced and developed. In the renewable-based generation sources, the phase-locked loop (PLL) is a well-known technique for operating grid-tied power converters for the estimation of the synchronization information and grid voltage monitoring. This paper aims to provide a comprehensive review of the recently developed PLL algorithms for grid synchronization applications. At first, various estimation techniques are discussed. Then, a comparison between various PLLs and possible future works are recommended.</p>

A brief survey on finite time and fixed time synchronization of complex dynamical networks and its applications

Complex networks have, in recent years, brought many innovative impacts to large-scale systems. However, great challenges also come forth due to distinct complex situations and imperative requirements in human life nowadays. This paper attempts to present an overview of recent progress of synchronization of complex dynamical networks and its applications. We focus on Finite-time and Fixed-time synchronization of complex dynamical networks with nonidentical discontinuous nodes, time delay, Class of Output-Coupling via continuous control and Markovian jump complex networks. Then, were view several applications of synchronization in complex networks, especially in neuroscience and power grids. The present limitations are summarized and future trends are explored and tentatively highlighted.

The fractional-order unified chaotic system: A general cascade synchronization method and application

In this paper, we extend the cascade synchronization of integer-order chaotic systems to function cascade synchronization of fractional-order chaotic systems. The nice feature of our method is that a fractional-order chaotic system will synchronize to another system via a scaling function. The rich choices of the scaling function turn our method more general than some existing methods. As applications, we take a fractional-order unified chaotic system as an illustrative example to test the effectiveness.

An Adaptive Frequency-Fixed Second-Order Generalized Integrator-Quadrature Signal Generator Using Fractional-Order Conformal Mapping Based Approach

The frequency-fixed second-order generalized integrator-based quadrature signal generator (FFSOGI-QSG) has been widely used in grid synchronization applications. The major limitations of using this technique are the unequal amplitudes of in-phase and quadrature-phase signals under grid frequency variation, which causes double-frequency oscillatory and offset errors in FFSOGI-based phase-locked loop output. To overcome the issues, in this letter, a modified complex analysis of FFSOGI-QSG using fractional-order-based conformal mapping approach has been presented, and an adaptive FFSOGI-QSG (AFFSOGI-QSG) is proposed. The proposed AFFSOGI-QSG can adapt itself to the grid frequency variations through the adjustment of single tuning parameter, i.e., fractional-order gain. The proposed structure is also found to inherit the simplicity of the FFSOGI-QSG without changing the order of the system while demonstrating an improved disturbance rejection capability under various grid disturbances. Performance of the proposed AFFSOGI-QSG is finally validated against some well-known SOGI-QSGs using numerical results obtained from the MATLAB and experimental results from the dSPACE DS1104 hardware.

Stability analysis and synchronization application for a 4D fractional-order system with infinite equilibria

This paper reports a 4D fractional-order memristor-based system with the flux-controlled memristor characterized by a cubic smooth monotonically increasing function. An unusual phenomenon is the fractional-order system has infinite equilibria. It is found that the local stability of these equilibria could be divided into three categories by the aid of local linearization technique. For those unstable equilibrium points, the dynamical behavior of the 4D fractional-order system depends on the differential order and initial conditions simultaneously. Through building a drive- response configuration, complete synchronization could be achieved with the proper initial value of response system. Finally, a novel information transmission scheme has been designed based on the switch synchronization of the fractional-order system, which has a larger key space. Two different types of information signals are taken as examples to verify the effectiveness of the proposed secure communication scheme.

Anti-phase collective synchronization with intrinsic in-phase coupling of two groups of electrochemical oscillators.

The synchronization of two groups of electrochemical oscillators is investigated during the electrodissolution of nickel in sulfuric acid. The oscillations are coupled through combined capacitance and resistance, so that in a single pair of oscillators (nearly) in-phase synchronization is obtained. The internal coupling within each group is relatively strong, but there is a phase difference between the fast and slow oscillators. The external coupling between the two groups is weak. The experiments show that the two groups can exhibit (nearly) anti-phase collective synchronization. Such synchronization occurs only when the external coupling is weak, and the interactions are delayed by the capacitance. When the external coupling is restricted to those between the fast and the slow elements, the anti-phase synchronization is more prominent. The results are interpreted with phase models. The theory predicts that, for anti-phase collective synchronization, there must be a minimum internal phase difference for a given shift in the phase coupling function. This condition is less stringent with external fast-to-slow coupling. The results provide a framework for applications of collective phase synchronization in modular networks where weak coupling between the groups can induce synchronization without rearrangements of the phase dynamics within the groups. This article is part of the theme issue 'Coupling functions: dynamical interaction mechanisms in the physical, biological and social sciences'.

Simultaneous EEG Acquisition System for Multiple Users: Development and Related Issues.

Social interaction is one of humans’ most important activities and many efforts have been made to understand the phenomenon. Recently, some investigators have attempted to apply advanced brain signal acquisition systems that allow dynamic brain activities to be measured simultaneously during social interactions. Most studies to date have investigated dyadic interactions, although multilateral interactions are more common in reality. However, it is believed that most studies have focused on such interactions because of methodological limitations, in that it is very difficult to design a well-controlled experiment for multiple users at a reasonable cost. Accordingly, there are few simultaneous acquisition systems for multiple users. In this study, we propose a design framework for an acquisition system that measures EEG data simultaneously in an environment with 10 or more people. Our proposed framework allowed us to acquire EEG data at up to 1 kHz frequency from up to 20 people simultaneously. Details of our acquisition system are described from hardware and software perspectives. In addition, various related issues that arose in the system’s development—such as synchronization techniques, system loads, electrodes, and applications—are discussed. In addition, simultaneous visual ERP experiments were conducted with a group of nine people to validate the EEG acquisition framework proposed. We found that our framework worked reasonably well with respect to less than 4 ms delay and average loss rates of 1%. It is expected that this system can be used in various hyperscanning studies, such as those on crowd psychology, large-scale human interactions, and collaborative brain–computer interface, among others.

A Global Convergence Estimator of Grid Voltage Parameters for More Electric Aircraft

Phase-locked loops (PLLs) are widely popular in applications of grid synchronization for single- and three-phase utility power systems. However, these PLL-based methods are usually designed for constant frequency grids and these schemes only have fast dynamics and good accuracy in a small local region (i.e., phase-locked region). When applying these PLLs in the grids of more electric aircraft (MEA), in which the grid frequency varies in a wide range (360–800 Hz), both the dynamic response and the steady-state accuracy of PLLs reduce significantly. In light of this, this article presents a global convergence method to estimate the frequency, positive- and negative-sequence components of grid voltage in MEA power systems. By analyzing the relationship between the DC-offset component, the grid voltage, and their derivatives, a mathematic model with the unknown parameters, which are the DC-offset component and the grid frequency, is established. Accordingly, a global estimator is proposed to estimate the grid voltage parameters accurately. A Lyaponov-based argument ensures that the proposed estimator is global convergent and it has the capability to eliminate the DC offset effect completely. The experimental results are provided to verify the effectiveness of the proposed estimator.

Digital Video Steganography Technology For Security Application

The paper proposes a technique on the digital video steganography. Various techniques are employed in order to achieve a higher secure data transmission these includes the cryptography, watermarking and steganography the steganography finds its application in the audio-video synchronization, copyright control and T.V.broadcasting specially in military areas the paper analyses the various improvements made in the security f the data transmission as well as the various methodologies adapted in achieving the same.the major difference between the steganography and the cryptgraphy is the latter has the cipher text which is coded and then transmitted while the former is embedded within a image or in a video frame so as to achieve the intended use.

A New Nine-Dimensional Chaotic Lorenz System with Quaternion Variables: Complicated Dynamics, Electronic Circuit Design, Anti-Anticipating Synchronization, and Chaotic Masking Communication Application

In this paper, a chaotic quaternion autonomous nonlinear structure is introduced and intends to be a contribution. It is the first nonlinear dynamical system with quaternion variables to be studied in the literature. With nine dimensions, the new system is a high-dimensional one. Several vital characteristics and features of this model are investigated, such as its Hamiltonian, symmetry, signal flow graph, dissipation, equilibriums and their stability, Lyapunov exponents, Lyapunov dimension, bifurcation diagrams, and chaotic behavior. A circuit implementation is designed to realize the new system, and a scheme is designed to achieve anti-anticipating synchronization (AAS) of two identical chaotic attractors with quaternion variables based on a Lyapunov function and active control. The concept of AAS is yet to be explored in the literature. A simulation experiment is designed and executed to illustrate the effectiveness of the acquired results. After synchronization, numerical outcomes are planned to explain the status variables and errors of these chaotic attractors to prove that AAS is achieved. The secure communication problem is studied based on the obtained events of the AAS of two identical nonlinear Lorenz systems with quaternion variables. AAS connecting the drive and response systems in chaotic systems with quaternion variables is the key to achieving communication. Signal encryption and restoration are simulated numerically.

Performance analysis of SRF-PLL and DDSRF-PLL algorithms for grid interactive inverters

In grid interactive power converter applications, phase locked loop (PLL) algorithms are very important to realize grid synchronization. The performance of PLL should not be affected by adverse conditions such as voltage unbalance, harmonics, frequency and phase changes. Otherwise, synchronization errors occur between the grid interactive inverter and the grid. In this paper, two different PLL algorithms are simulated by modeling under MATLAB/Simulink. The performances of the PLLs are comparatively presented under four different grid conditions such as balanced, unbalanced, harmonics and variable frequency. In this study, synchronous reference frame-PLL (SRF-PLL) and decoupled double synchronous reference frame-PLL (DDSRF-PLL) which are mostly used, state-of-arts and effective PLL algorithms are analyzed by modeling in grid synchronization applications. It has also been demonstrated the positive and negative aspects of the PLLs based on the obtained results.

Multiscroll chaotic system with sigmoid nonlinearity and its fractional order form with synchronization application

In this paper, a multiscroll snap oscillator with hyperbolic tangent function is proposed. There is no limitation in the number of scrolls and it can be increased by proper choice of a specific function. The Lyapunov exponents of the proposed system are obtained to testify the chaotic behavior of the system. Fractional order multiscroll system is derived from its integer order model by using the Adams–Bashforth–Moulton algorithm. A new scheme is applied in order to investigate the synchronization of the multiscroll systems. The main objective of the paper is to propose a multiscroll attractor and show that the number of scrolls can be controlled by the only nonlinear function. Such systems are less investigated in the literatures and has many real time applications like image and voice encryption, random number generators, chaos based communication systems and so on.

A High Precision Time Synchronization Method for Smart Grid based on Beidou Satellite System

With the rapid development of power grid and the large-scale application of automation equipment in power station, the requirement of high precision time synchronization for power system production and control is rapid growth. The accuracy of time synchronization for power system is an important basis to guarantee power network operation control and fault analysis, and a fundamental guarantee to improve power network accident analysis and stability control. In order to ensure that the automatic device receives accurate time synchronization signal, time monitoring and application schemes of different technical routes are studied in this paper. It is proposed that the precise monitoring based on the direct measurement of Beidou can realize high precision time monitoring and synchronization, better guarantee the accuracy of time synchronization between power equipment, ensure the precision of phase measurement, line fault location and time sequence recording of power system, and provide technical support for the stable and reliable operation of power system.

Synchronization for Incommensurate Riemann–Liouville Fractional-Order Time-Delayed Competitive Neural Networks With Different Time Scales and Known or Unknown Parameters1

Synchronization for incommensurate Riemann–Liouville fractional competitive neural networks (CNN) with different time scales is investigated in this paper. Time delays and unknown parameters are concerned in the model, which is more practical. Two simple and effective controllers are proposed, respectively, such that synchronization between the salve system and the master system with known or unknown parameters can be achieved. The methods are more general and less conservative which can also be applied to commensurate integer-order systems and commensurate fractional systems. Furthermore, two numerical ensamples are provided to show the feasibility of the approach. Based on the chaotic masking method, the example of chaos synchronization application for secure communication is provided.