Abstract: This paper studies synchronization via pinning control on general complex dynamical networks, such as strongly connected networks, networks with a directed spanning tree, weakly connected networks, and directed forests. A criterion for ensuring network synchronization on strongly connected networks is given. It is found that the vertices with very small in-degrees should be pinned first. In addition, it is shown that the original condition with controllers can be reformulated such that it does not depend on the form of the chosen controllers, which implies that the vertices with very large out-degrees may be pinned. Then, a criterion for achieving synchronization on networks with a directed spanning tree, which can be composed of many strongly connected components, is derived. It is found that the strongly connected components with very few connections from other components should be controlled and the components with many connections from other components can achieve synchronization even without controls...

Abstract: In this paper, global exponential synchronization stability in an array of linearly diffusively coupled reaction-diffusion neural networks with time-varying delays is investigated by adding impulsive controller to a small fraction of nodes (pinning-impulsive controller). In order to overcome the difficulty resulting from the fact that the impulsive controller affects only the dynamical behaviors of the controlled nodes, a new analysis method is developed. By using the developed method, two known lemmas on stability of delayed functional differential equation with and without impulses, and Lyapunov stability theory, several novel and easily verified synchronization criteria guaranteeing the whole network will be pinned to a homogenous solution are derived. Moreover, the effects of the pinning-impulsive controller and the dynamics of the uncontrolled nodes and the diffusive couplings on the synchronization process are explicitly expressed in the obtained criteria. Our results also show that we can always de...

Abstract: A method and an apparatus for performing synchronization by a first device in a Device-to-Device (D2D) network are provided. The method includes detecting a synchronization signal from at least one second device during one period, determining a phase adjustment value depending on a number of synchronization signals, which have been detected from the at least one second device during the one period, adjusting a phase value of a first device using the phase adjustment value, and transmitting a synchronization signal if the phase value of the first device reaches a predetermined specific value.

Abstract: A method and apparatus are provided for performing acquisition, synchronization and cell selection within an MIMO-OFDM communication system. A coarse synchronization is performed to determine a searching window. A fine synchronization is then performed by measuring correlations between subsets of signal samples, whose first signal sample lies within the searching window, and known values. The correlations are performed in the frequency domain of the received signal. In a multiple-output OFDM system, each antenna of the OFDM transmitter has a unique known value. The known value is transmitted as pairs of consecutive pilot symbols, each pair of pilot symbols being transmitted at the same subset of sub-carrier frequencies within the OFDM frame.

Abstract: In this paper, the distributed synchronization problem of networks of agent systems with controllers and nonlinearities subject to Bernoulli switchings is investigated. Controllers and adaptive updating laws injected in each vertex of networks depend on the state information of its neighborhood. Three sets of Bernoulli stochastic variables are introduced to describe the occurrence probabilities of distributed adaptive controllers, updating laws and nonlinearities, respectively. By the Lyapunov functions method, we show that the distributed synchronization of networks composed of agent systems with multiple randomly occurring nonlinearities, multiple randomly occurring controllers, and multiple randomly occurring updating laws can be achieved in mean square under certain criteria. The conditions derived in this paper can be solved by semi-definite programming. Moreover, by mathematical analysis, we find that the coupling strength, the probabilities of the Bernoulli stochastic variables, and the form of nonlinearities have great impacts on the convergence speed and the terminal control strength. The synchronization criteria and the observed phenomena are demonstrated by several numerical simulation examples. In addition, the advantage of distributed adaptive controllers over conventional adaptive controllers is illustrated.

Abstract: We introduce and characterize two different measures which quantify the level of synchronization of coupled continuous variable quantum systems. The two measures allow us to extend to the quantum domain the notions of complete and phase synchronization. The Heisenberg principle sets a universal bound to complete synchronization. The measure of phase synchronization is, in principle, unbounded; however, in the absence of quantum resources (e.g., squeezing) the synchronization level is bounded below a certain threshold. We elucidate some interesting connections between entanglement and synchronization and, finally, discuss an application based on quantum optomechanical systems.

Abstract: This paper presents the most exhaustive study of synchronization to date. We span multiple layers, from hardware cache-coherence protocols up to high-level concurrent software. We do so on different types of architectures, from single-socket -- uniform and non-uniform -- to multi-socket -- directory and broadcast-based -- many-cores. We draw a set of observations that, roughly speaking, imply that scalability of synchronization is mainly a property of the hardware.

Abstract: Control problems such as multirobot control, distributed intelligence, swarm intelligence, distributed decision, distributed cognition, congestion control in networks, collective motion in biology, oscillator synchronization in physics, parallelization in optimization theory, distributed estimation, cooperative estimation, equilibria in economics, social interaction modeling, and game theory may be analyzed under the theory of interconnected dynamic systems. Those topics have several overlapping research communities; for that reason they are characterized by different definitions and a variety of approaches ranging from rigorous mathematical analysis to trial-and-error experimental study or emulation by observation of natural phenomena. The areas involved concern robotics, dynamic systems, computer science, signal theory, biology, economics, and mathematics. A shared taxonomy is missing; for example, dynamic systems can be identified in robots, agents, nodes, processors, and entities. An ensemble is called a group, network, platoon, swarm, team, and cluster, and the algorithms are defined as controllers, protocols, and dynamics. In the following, the term agent is used to denote the single dynamic system and network or collective the ensemble.

Abstract: Explosive synchronization (ES) has recently attracted much attention, where its two necessary conditions are found to be a scale-free network topology and a positive correlation between the natural frequencies of the oscillators and their degrees. Here we present a framework for ES to be observed in a general complex network, where a positive correlation between coupling strengths of the oscillators and the absolute of their natural frequencies is assumed and the previous studies are included as specific cases. In the framework, the previous two necessary conditions are replaced by another one, thus fundamentally deepening the understanding of the microscopic mechanism toward synchronization. A rigorous analytical treatment by a mean field is provided to explain the mechanism of ES in this alternate framework.

Abstract: The problem of matching not just two, but m different sets of objects to each other arises in many contexts, including finding the correspondence between feature points across multiple images in computer vision. At present it is usually solved by matching the sets pairwise, in series. In contrast, we propose a new method, Permutation Synchronization, which finds all the matchings jointly, in one shot, via a relaxation to eigenvector decomposition. The resulting algorithm is both computationally efficient, and, as we demonstrate with theoretical arguments as well as experimental results, much more stable to noise than previous methods.

Abstract: The Kalray MPPA-256 processor integrates 256 user cores and 32 system cores on a chip with 28nm CMOS technology. Each core implements a 32-bit 5-issue VLIW architecture. These cores are distributed across 16 compute clusters of 16+1 cores, and 4 quad-core I/O subsystems. Each compute cluster and I/O subsystem owns a private address space, while communication and synchronization between them is ensured by data and control Networks-On-Chip (NoC). The MPPA-256 processor is also fitted with a variety of I/O controllers, in particular DDR, PCI, Ethernet, Interlaken and GPIO. We demonstrate that the MPPA-256 processor clustered manycore architecture is effective on two different classes of applications: embedded computing, with the implementation of a professional H.264 video encoder that runs in real-time at low power; and high-performance computing, with the acceleration of a financial option pricing application. In the first case, a cyclostatic dataflow programming environment is utilized, that automates application distribution over the execution resources. In the second case, an explicit parallel programming model based on POSIX processes, threads, and NoC-specific IPC is used.

Abstract: Methods and systems are provided for synchronizing and sharing data objects in a cloud based social networking environment of the type including a collaboration cloud. The method includes defining a sharing configuration within the collaboration cloud to include a second computing device; running a dedicated client synchronization application on a first computing device; creating a sync folder on the first computing device using the client synchronization application; updating a data object using the first computing device; adding the updated data object to the sync folder; automatically synchronizing the updated data object with the collaboration cloud; and propagating, using the collaboration cloud, the updated data object to the second computing device.

Abstract: A method includes receiving and storing sensor data including a first plurality of data points indicative of a plurality of respective states of the environment external to a vehicle at a plurality of respective times, operational data including a second plurality of data points indicative of a plurality of respective states of an operational parameter of the vehicle at a plurality of respective times, and synchronization data. The method also includes generating an animated re-creation of an event involving the vehicle using the stored data, and causing the animated re-creation of the event to be displayed.

Abstract: A Comment on the Letter by F. Wilczek, Phys. Rev. Lett. 109, 160401 (2012). The authors of the Letter offer a Reply.

Abstract: Synchronization is one of the paradigmatic phenomena in the study of complex systems. It has been explored theoretically and experimentally mostly to understand natural phenomena, but also in view of technological applications. Although several mechanisms and conditions for synchronous behavior in spatially extended systems and networks have been identified, the emergence of this phenomenon has been largely unexplored in quantum systems until very recently. Here we discuss synchronization in quantum networks of different harmonic oscillators relaxing towards a stationary state, being essential the form of dissipation. By local tuning of one of the oscillators, we establish the conditions for synchronous dynamics, in the whole network or in a motif. Beyond the classical regime we show that synchronization between (even unlinked) nodes witnesses the presence of quantum correlations and entanglement. Furthermore, synchronization and entanglement can be induced between two different oscillators if properly linked to a random network.

Abstract: Abstract. In this paper, we study the original Kuramoto oscillators and the generalized Kuramoto oscillators with directed coupling topology. For the original Kuramoto model with identical oscillators, we obtain that frequency synchronization can occur for all initial phase configurations distributed over the whole circle, which is proved by means of a new method based on the Lojasiewicz inequality for gradient systems of analytic functions. This improves the corresponding result in [S.-Y. Ha, T. Ha, and J.-H. Kim, Physica D 239, 1692–1700, 2010], where the authors only considered initial phase configurations distributed over the open half circle. For the generalized Kuramoto model with directed coupling topology, we show that when the phases of oscillators are distributed over the half circle and the coupling strength is sufficiently large, frequency synchronization is guaranteed. This improves and extends the previous results in [N. Chopra and M. W. Spong, IEEE Trans. Automat. Control 54, 353–357, 2009], [S.Y. Ha, T. Ha, and J.H. Kim, Physica D 239, 1692–1700, 2010], and [Y.P. Choi, S.Y. Ha, S. Jung, and Y. Kim, Physica D 241, 735–754, 2012], where the corresponding results hold in the original Kuramoto model for initial phase configurations whose diameters are smaller than π 2 or π. Finally, we extend the result to the case of switching topology.

Abstract: In this paper, we study the finite-time synchronization problem for linearly coupled complex networks with discontinuous nonidentical nodes. Firstly, new conditions for general discontinuous chaotic systems is proposed, which is easy to be verified. Secondly, a set of new controllers are designed such that the considered model can be finite-timely synchronized onto any target node with discontinuous functions. Based on a finite-time stability theorem for equations with discontinuous right-hand and inequality techniques, several sufficient conditions are obtained to ensure the synchronization goal. Results of this paper are general, and they extend and improve existing results on both continuous and discontinuous complex networks. Finally, numerical example, in which a BA scale-free network with discontinuous Sprott and Chua circuits is finite-timely synchronized onto discontinuous Chen system, is given to show the effectiveness of our new results.

Abstract: SUMMARY This paper addresses attitude synchronization and tracking problems in spacecraft formation in the presence of model uncertainties and external disturbances. A decentralized adaptive sliding mode control law is proposed using undirected interspacecraft communication topology and analyzed based on algebraic graph theory. A multispacecraft sliding manifold is derived, on which each spacecraft approaches desired time-varying attitude and angular velocity while maintaining attitude synchronization with the other spacecraft in the formation. A control law is then developed to ensure convergence to the sliding manifold. The stability of the resulting closed-loop system is proved by application of Barbalat's Lemma. Simulation results demonstrate the effectiveness of the proposed attitude synchronization and tracking methodology. Copyright © 2012 John Wiley & Sons, Ltd.

Abstract: The utility model discloses electric power automation equipment, which comprises an information processing module. The information processing module comprises a main processor and a wireless transceiver module. The wireless transceiver module and the main processor are in communication with each other based on the wireless communication protocol. The communication of the information processing module is realized also based on the wireless communication protocol. According to the technical scheme of the utility model, the automatic synchronization and the mutual communication among automation equipment are carried out in a wireless manner, so that the data transmission, including resource sharing, downloading and the like, can be realized. Therefore, the electric power automation equipment is convenient, efficient and safe to use.

Abstract: Like shared-memory multi-threaded programs, event-driven programs such as client-side web applications are susceptible to data races that are hard to reproduce and debug. Race detection for such programs is hampered by their pervasive use of ad hoc synchronization, which can lead to a prohibitive number of false positives. Race detection also faces a scalability challenge, as a large number of short-running event handlers can quickly overwhelm standard vector-clock-based techniques.This paper presents several novel contributions that address both of these challenges. First, we introduce race coverage, a systematic method for exposing ad hoc synchronization and other (potentially harmful) races to the user, significantly reducing false positives. Second, we present an efficient connectivity algorithm for computing race coverage. The algorithm is based on chain decomposition and leverages the structure of event-driven programs to dramatically decrease the overhead of vector clocks.We implemented our techniques in a tool called EventRacer and evaluated it on a number of public web sites. The results indicate substantial performance and precision improvements of our approach over the state-of-the-art. Using EventRacer, we found many harmful races, most of which are beyond the reach of current techniques.

Abstract: Techniques are disclosed for enabling selective subfolder synchronization in a cloud-based environment. In one embodiment, a method comprises, in response to a selection, from a user, of a first synchronization state of a first folder in a workspace, synchronizing content of the first folder associated with the user based on the first synchronization state regardless of a second synchronization state of a second folder in the workspace. The first folder is a subfolder of the second folder. The workspace is provided by a server of a cloud-based environment, and is shared among the user and one or more collaborators of the user. Among other advantages, embodiments disclosed herein provide fine-grained control to the users of a cloud collaboration environment over what folder(s) in their workspace is to be shared and/or synchronized.

Abstract: This research work describes the modelling of two novel 3-D chaotic systems, the first with a hyperbolic sinusoidal nonlinearity and two quadratic nonlinearities (denoted as system (A)) and the second with a hyperbolic cosinusoidal nonlinearity and two quadratic nonlinearities (denoted as system (B)). In this work, a detailed qualitative analysis of the novel chaotic systems (A) and (B) has been presented, and the Lyapunov exponents and Kaplan-Yorke dimension of these chaotic systems have been obtained. It is found that the maximal Lyapunov exponent (MLE) for the novel chaotic systems (A) and (B) has a large value, viz. for the system (A) and for the system (B). Thus, both the novel chaotic systems (A) and (B) display strong chaotic behaviour. This research work also discusses the problem of finding adaptive controllers for the global chaos synchronization of identical chaotic systems (A), identical chaotic systems (B) and nonidentical chaotic systems (A) and (B) with unknown system parameters. The adaptive controllers for achieving global chaos synchronization of the novel chaotic systems (A) and (B) have been derived using adaptive control theory and Lyapunov stability theory. MATLAB simulations have been shown to illustrate the novel chaotic systems (A) and (B), and also the adaptive synchronization results derived for the novel chaotic systems (A) and (B).

Abstract: The emergence of dynamical abrupt transitions in the macroscopic state of a system is currently a subject of the utmost interest. Given a set of phase oscillators networking with a generic wiring of connections and displaying a generic frequency distribution, we show how combining dynamical local information on frequency mismatches and global information on the graph topology suggests a judicious and yet practical weighting procedure which is able to induce and enhance explosive, irreversible, transitions to synchronization. We report extensive numerical and analytical evidence of the validity and scalability of such a procedure for different initial frequency distributions, for both homogeneous and heterogeneous networks, as well as for both linear and nonlinear weighting functions. We furthermore report on the possibility of parametrically controlling the width and extent of the hysteretic region of coexistence of the unsynchronized and synchronized states.

Abstract: As tools for personal storage, file synchronization and data sharing, cloud storage services such as Dropbox have quickly gained popularity. These services provide users with ubiquitous, reliable data storage that can be automatically synced across multiple devices, and also shared among a group of users. To minimize the network overhead, cloud storage services employ binary diff, data compression, and other mechanisms when transferring updates among users. However, despite these optimizations, we observe that in the presence of frequent, short updates to user data, the network traffic generated by cloud storage services often exhibits pathological inefficiencies. Through comprehensive measurements and detailed analysis, we demonstrate that many cloud storage applications generate session maintenance traffic that far exceeds the useful update traffic. We refer to this behavior as the traffic overuse problem. To address this problem, we propose the update-batched delayed synchronization (UDS) mechanism. Acting as a middleware between the user’s file storage system and a cloud storage application, UDS batches updates from clients to significantly reduce the overhead caused by session maintenance traffic, while preserving the rapid file synchronization that users expect from cloud storage services. Furthermore, we extend UDS with a backwards compatible Linux kernel modification that further improves the performance of cloud storage applications by reducing the CPU usage.

Abstract: We study experimentally the synchronization patterns in time-delayed directed Boolean networks of excitable systems. We observe a transition in the network dynamics when the refractory time of the individual systems is adjusted. When the refractory time is on the same order of magnitude as the mean link time delays or the heterogeneities of the link time delays, cluster synchronization patterns change, or are suppressed entirely, respectively. We also show that these transitions occur when we change the properties of only a small number of driver nodes identified by their larger in degree; hence, the synchronization patterns can be controlled locally by these nodes. Our findings have implications for synchronization in biological neural networks.

Abstract: In this study, we investigate a class of chaotic synchronization and anti-synchronization with stochastic parameters. A controller is composed of a compensation controller and a fuzzy controller which is designed based on fractional stability theory. Three typical examples, including the synchronization between an integer-order Chen system and a fractional-order Lu system, the anti-synchronization of different 4D fractional-order hyperchaotic systems with non-identical orders, and the synchronization between a 3D integer-order chaotic system and a 4D fractional-order hyperchaos system, are presented to illustrate the effectiveness of the controller. The numerical simulation results and theoretical analysis both demonstrate the effectiveness of the proposed approach. Overall, this study presents new insights concerning the concepts of synchronization and anti-synchronization, synchronization and control, the relationship of fractional and integer order nonlinear systems.