Exact Synchronization Research Articles

Peer-to-peer mobile data flow in a crop field

The adoption of mobile technology in the agriculture sector can lead to benefits such as high productivity, improvement in mechanisation, increment in revenue, and timely information accessibility by farmers. The problem, however, is that mobile devices communicate over wireless mediums that can be unreliable; and when data states are kept on distributed nodes, inconsistencies can arise due to inefficiencies in the flow propagation of the updated agronomic data. This work describes a new key-value storage synchronisation workflow using exact set reconciliation and bloom filters. The proposed flow algorithm with its two-phase architect, with the first one being approximate synchronisation and the second one being exact synchronisation, provides better performance regarding bandwidth management. In addition, the usage of redundancy detection in the synchronisation mechanism makes it possible for the proposed algorithm to operate in a peer-to-peer environment, independent of any centralised server.

Network Synchronization with Convexity

In this paper, we establish a few new synchronization conditions for complex networks with nonlinear and nonidentical self-dynamics with switching directed communication graphs. In light of the recent works on distributed subgradient methods, we impose integral convexity for the nonlinear node self-dynamics in the sense that the self-dynamics of a given node is the gradient of some concave function corresponding to that node. The node couplings are assumed to be linear but with switching directed communication graphs. Several sufficient and/or necessary conditions are established for exact or approximate synchronization over the considered complex networks. These results show when and how nonlinear node self-dynamics may cooperate with the linear diffusive coupling, which eventually leads to network synchronization conditions under relaxed connectivity requirements.

Sur l'état de synchronisation exacte d'un système couplé d'équations des ondes

In this Note, we consider the determination of the state of exact synchronization for a coupled system of wave equations. In a special case, the state of exact synchronization can be uniquely determined whatever the boundary controls would be chosen. In the general case, the state of exact synchronization depends on the boundary controls that realize the exact synchronization. However, we can estimate the difference between the state of exact synchronization and the solution to a problem independent of boundary controls. The determination of the state of exact synchronization by groups is also discussed.

A note on the exact synchronization by groups for a coupled system of wave equations

By means of a non‐exact controllability result, we show the necessity of the conditions of compatibility for the exact synchronization by two groups for a coupled system of wave equations with Dirichlet boundary controls. Copyright © 2014 John Wiley & Sons, Ltd.

Synchronization of time-delayed chemically coupled burst-spiking neurons with correlated noises.

Synchronization of two time-delayed chemically coupled neurons with burst-spiking states is studied. Different from the previous study by N. Buric et al. (Phys. Rev. E 78, 036211 (2008)), it is found that exactly synchronous burst-spiking dynamics can occur for small coupling strengths and time delays. The results are confirmed by common time delays and non-equal time delays. When common noise is added to the two neurons, synchronization is enhanced as noise strength is increased. But the results are different for larger time delay and smaller time delay. When noises are correlated, it is found that only strong noises with large correlation coefficient can induce exact synchronization. Even one percent of independent noises can influence synchronization much.

Heterogeneous delays making parents synchronized: A coupled maps on Cayley tree model

We study the phase synchronized clusters in the diffusively coupled maps on the Cayley tree networks for heterogeneous delay values. Cayley tree networks comprise of two parts: the inner nodes and the boundary nodes. We find that heterogeneous delays lead to various cluster states, such as; (a) cluster state consisting of inner nodes and boundary nodes, and (b) cluster state consisting of only boundary nodes. The former state may comprise of nodes from all the generations forming self-organized cluster or nodes from few generations yielding driven clusters depending upon on the parity of heterogeneous delay values. Furthermore, heterogeneity in delays leads to the lag synchronization between the siblings lying on the boundary by destroying the exact synchronization among them. The time lag being equal to the difference in the delay values. The Lyapunov function analysis sheds light on the destruction of the exact synchrony among the last generation nodes. To the end we discuss the relevance of our results with respect to their applications in the family business as well as in understanding the occurrence of genetic diseases.

Entropy and stability of phase synchronisation of oscillators on networks

I examine the role of entropy in the transition from incoherence to phase synchronisation in the Kuramoto model of N coupled phase oscillators on a general undirected network. In a Hamiltonian ‘action-angle’ formulation, auxiliary variables Ji combine with the phases θi to determine a conserved system with a 2N dimensional phase space. In the vicinity of the fixed point for phase synchronisation, θi≈θj, which is known to be stable, the auxiliary variables Ji exhibit instability. This manifests Liouville’s Theorem in the phase synchronised regime in that contraction in the θi parts of phase space are compensated for by expansion in the auxiliary dimensions. I formulate an entropy rate based on the projection of the Ji onto eigenvectors of the graph Laplacian that satisfies Pesin’s Theorem. This leads to the insight that the evolution to phase synchronisation of the Kuramoto model is equivalent to the approach to a state of monotonically increasing entropy. Indeed, for unequal intrinsic frequencies on the nodes, the networks that achieve the closest to exact phase synchronisation are those which enjoy the highest entropy production. I compare numerical results for a range of networks.

Anti-phase synchronization and ergodicity in arrays of oscillators coupled by an elastic force

We have proposed a mechanism of interaction between two non-linear dissipative oscillators, leading to exact and robust anti-phase and in-phase synchronization. The system we have analyzed is a model for the Huygens's two pendulum clocks system, as well as a model for synchronization mediated by an elastic media. Here, we extend these results to arrays, finite or infinite, of conservative pendula coupled by linear elastic forces. We show that, for two interacting pendula, this mechanism leads always to synchronized anti-phase small amplitude oscillations, and it is robust upon variation of the parameters. For three or more interacting pendula, this mechanism leads always to ergodic non-synchronized oscillations. In the continuum limit, the pattern of synchronization is described by a quasi-periodic longitudinal wave.

Diversity analysis of distributed linear convolutive space‐time codes for time–frequency asynchronous cooperative networks

This study analyses the achievable cooperative diversity order of the distributed linear convolutional space-time coding (DLC-STC) scheme for time–frequency asynchronous cooperative networks. The authors first prove that perfect time or frequency synchronisation is impractical for cooperative networks with multiple relays serving multiple destinations even when the relays know all accurate time delays and frequency offsets. Then the DLC-STC scheme, in which the exact time synchronisation at the relay nodes is unnecessary, is introduced into this type of cooperative networks. This study proves that the achievable time–frequency asynchronous cooperative diversity order of the DLC-STC scheme with maximum-likelihood receivers is equal to the number of relays. Simulation results verify the analysis.

Exact boundary synchronization for a coupled system of 1-D wave equations

Several kinds of exact synchronizations and the generalized exact synchronization are introduced for a coupled system of 1-D wave equations with various boundary conditions and we show that these synchronizations can be realized by means of some boundary controls.

A Mechanism for the Crossing of Orthogonal Magnetic Wires in Multiferroic Nanomagnet Logic

We report time division multiplexing-based seven-phase clocking mechanism for the crossing of magnetic wires by in-plane multiferroic nanomagnet logic (m-NML). By reasonably setting hold time and sequence of applied stress (or voltage), the proposed multiferroic clocking ensures correct signal propagation of two orthogonal m-NML wires (or paths). The effects of magnetostrictive layer thickness on required seven-phase clock period and strain are investigated. Accordingly, a link scheme between early four-phase clocking and proposed seven-phase multiferroic clocking is developed by compressing seven-phase clock period. Thus, exact computation synchronization and pipelining in the entire NML circuit have been implemented. Finally, power consumption in the proposed m-NML crossing is discussed. The result shows that the m-NML signal crossing can be achieved with an energy dissipation of only about 533 aJ.

A note on the exact synchronization by groups for a coupled system of wave equations

By means of a non‐exact controllability result, we show the necessity of the conditions of compatibility for the exact synchronization by two groups for a coupled system of wave equations with Dirichlet boundary controls. Copyright © 2013 John Wiley & Sons, Ltd.

Practical and Exact Synchronization of Complex Networks of Fractional Order Nonlinear Systems

Based on stability theorems for nonlinear differential systems with commensurate fractional orders and on the use of a nonlinear coupling that does not require the total elimination of the nonlinear part of the system, we have obtained an analytical result to ensure the practical and exact synchronization of complex networks with fractional nonlinear order systems as elements. As an application, we present the synchronization with different kinds of fractional differential systems. We use some numerical results to verify the effectiveness of the proposed method.

Generalized exact boundary synchronization for a coupled system of wave equations

By means of Moore-Penrose generalized inverse, a general framework is presented to treat the generalized exact boundary synchronization for a coupled systems of wave equations.

Networked dynamical systems with linear coupling: Synchronisation patterns, coherence and other behaviours

Many physical and biochemical systems are well modelled as a network of identical non-linear dynamical elements with linear coupling between them. An important question is how network structure affects chaotic dynamics, for example, by patterns of synchronisation and coherence. It is shown that small networks can be characterised precisely into patterns of exact synchronisation and large networks characterised by partial synchronisation at the local and global scale. Exact synchronisation modes are explained using tools of symmetry groups and invariance, and partial synchronisation is explained by finite-time shadowing of exact synchronisation modes.

Audiovisual presentation of video-recorded stimuli at a high frame rate

A method for creating and presenting video-recorded synchronized audiovisual stimuli at a high frame rate-which would be highly useful for psychophysical studies on, for example, just-noticeable differences and gating-is presented. Methods for accomplishing this include recording audio and video separately using an exact synchronization signal, editing the recordings and finding exact synchronization points, and presenting the synchronized audiovisual stimuli with a desired frame rate on a cathode ray tube display using MATLAB and Psychophysics Toolbox 3. The methods from an empirical gating study (Moradi, Lidestam, & Rönnberg, Frontiers in Psychology 4:359, 2013) are presented as an example of the implementation of playback at 120 fps.

Exact boundary synchronization for a coupled system of 1-D wave equations with coupled boundary conditions of dissipative type

Several kinds of exact synchronizations are introduced for a coupledsystem of 1-D wave equations with coupled boundary conditions of dissipative typeand these synchronizations can be realized by means of someboundary controls.

Exact synchronization bound for coupled time-delay systems

We obtain an exact bound for synchronization in coupled time-delay systems using the generalized Halanay inequality for the general case of time-dependent delay, coupling, and coefficients. Furthermore, we show that the same analysis is applicable to both uni- and bidirectionally coupled time-delay systems with an appropriate evolution equation for their synchronization manifold, which can also be defined for different types of synchronization. The exact synchronization bound assures an exponential stabilization of the synchronization manifold which is crucial for applications. The analytical synchronization bound is independent of the nature of the modulation and can be applied to any time-delay system satisfying a Lipschitz condition. The analytical results are corroborated numerically using the Ikeda system.

Asynchronous Communication: Exact Synchronization, Universality, and Dispersion

Recently, Tchamkerten and coworkers proposed a novel variation of the problem of joint synchronization and error correction. This paper considers a strengthened formulation that requires the decoder to estimate both the message and the location of the codeword exactly. Such a scheme allows for transmitting data bits in the synchronization phase of the communication, thereby improving bandwidth and energy efficiencies. It is shown that the capacity region remains unchanged under the exact synchronization requirement. Furthermore, asynchronous capacity can be achieved by universal (channel independent) codes. Comparisons with earlier results on another (delay compensated) definition of rate are made. The finite blocklength regime is investigated and it is demonstrated that even for moderate blocklengths, it is possible to construct capacity-achieving codes that tolerate exponential level of asynchronism and experience only a rather small loss in rate compared to the perfectly synchronized setting; in particular, the channel dispersion does not suffer any degradation due to asynchronism. For the binary symmetric channel, a translation (coset) of a good linear code is shown to achieve the capacity-synchronization tradeoff.

Substructurability and exact synchronisation analysis

SUMMARY A numerical-substructure-based framework for the synthesis of substructured dynamics, substructurability, and exact synchronisation controllers using state-space methods is presented in this paper. Substructurability is used to analyse the dynamic properties of numerical substructures and transfer systems, on the basis of controllability, substructured eigenvalue, and condition number techniques. Exact synchronisation controllers are designed under the assumptions of unknown parameters of the tested components and are used to achieve a higher level of synchronisation over the transient state. Implementation studies present a synchronised-component-based approach for the controller design and also verify that (1) substructured eigenvalues provide a general indicator to predict stability and performance in advance and (2) slow substructured eigenvalues due to low damping or large mass within a numerical substructure tend to yield ineffective and inefficient tests. Copyright © 2013 John Wiley & Sons, Ltd.