Generalized synchronization in autooscillatory media

The phenomenon of generalized chaotic synchronization has been found in autooscillatory media described by the Ginzburg-Landau equations. A mechanism responsible for the establishment of generalized synchronization regimes in one-way coupled autooscillatory media exhibiting chaotic spatiotemporal behavior is proposed. The mechanism of generalized synchronization is described based on an analysis of a modified Ginzburg-Landau equation with an additional dissipative term.     

Generalized synchronization of chaotic oscillators

The behavior of two unidirectionally coupled chaotic oscillators near the boundary of their generalized synchronization is analyzed. Using the modified system method, the position of this boundary on the plane of control parameters is considered and the physical mechanisms leading to the establishment of the generalized synchronization regime are elucidated.     

Generalized synchronization in Ginzburg-Landau equations with local coupling

The establishment of generalized chaotic synchronization in Ginzburg-Landau equations unidirectionally coupled at discrete points of space (local coupling) has been studied. It is shown that generalized synchronization regimes are also established with this type of coupling, but the necessary intensity of coupling is significantly higher than that in the case of a spatially homogeneous coupling.     

Schedule synchronization for public transit networks

Summary The problem of minimizing waiting times of passengers who want to change communication routes at transfer stations is considered. The paper contains heuristics (regret-methods, improvement algorithms, simulated annealing) as well as a branch and boundalgorithm and provides computational results, some of them gained with practical data.

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Zusammenfassung Betrachtet wird das Problem der Fahrplangestaltung im öffentlichen (Personen-)Nahverkehr mit dem Ziel der Minimierung der Summe der Wartezeiten für Umsteiger. Es werden heuristische Lösungsverfahren (Regret-Methoden, Verbesserungsverfahren, Simulated Annealing) sowie ein Branch-and- Bound-Algorithmus beschrieben. Die Verfahren wurden u. a. anhand von Daten aus der Praxis getestet.

     

Generalized synchronization of chaotic oscillators as a partial case of time scale synchronization

Two coupled dynamical systems of the Rössler type are studied, and it is shown that the generalized synchronization regime can be considered as a partial case of the time scale synchronization process.     

Generalized synchronization in a system of coupled klystron chaotic oscillators

The phenomenon of generalized chaotic synchronization has been studied in a system of two unidirectionally coupled chaotic oscillators modeling two-sresonator klystron autooscillators. A mechanism explaining the observed behavior is presented.     

A method of distinguishing between the characteristic phases of behavior in complex networks in the intermittent generalized synchronization regime

A method of identification of the phases of synchronous and asynchronous intervals in the time realizations of interacting chaotic systems representing elements of a network with complex coupling topology in the state of transition to the generalized synchronization regime is proposed. The method allows determining the duration of the phases of synchronous and asynchronous dynamics, which potentially allows analyzing the statistical characteristics of the intermittent behavior of the discussed systems.     

Least squares timestamp synchronization for local broadcast networks

The analysis of computer network experiments strongly relies on event log files recorded by the participating network nodes during the experiment. Timing related issues play an important role here for a number of central parameters like, e.g., end-to-end delay. As each node uses its local clock to timestamp the events in the log files, the large deviation of standard crystal oscillator based clocks imposes some big problems. We look at this issue in the case of networks with local broadcast media, where occurring transmissions can often be observed by multiple network nodes. We have developed a method to correct the timestamps in such an environment in a previous paper. Here, we present a second solution. For this new solution, we give bounds on the synchronization quality and compare the two approaches by means of simulation.     

Generalized Hirsch h-index for disclosing latent facts in citation networks

What is the value of a scientist and its impact upon the scientific thinking? How can we measure the prestige of a journal or a conference? The evaluation of the scientific work of a scientist and the estimation of the quality of a journal or conference has long attracted significant interest, due to the benefits by obtaining an unbiased and fair criterion. Although it appears to be simple, defining a quality metric is not an easy task. To overcome the disadvantages of the present metrics used for ranking scientists and journals, J. E. Hirsch proposed a pioneering metric, the now famous h-index. In this article we demonstrate several inefficiencies of this index and develop a pair of generalizations and effective variants of it to deal with scientist ranking and publication forum ranking. The new citation indices are able to disclose trendsetters in scientific research, as well as researchers that constantly shape their field with their influential work, no matter how old they are. We exhibit the effectiveness and the benefits of the new indices to unfold the full potential of the h-index, with extensive experimental results obtained from the DBLP, a widely known on-line digital library.     

移动传感器网络的一种基于自适应扩散的时间同步协议

针对移动传感器网络中网络拓扑动态变化和通信链路不稳定的特性,提出了一种基于自适应扩散的时间同步协议(SDTS).该协议分为被动同步和主动同步两种同步方式,被动同步方式下已同步节点根据自身和网络当前的状态,以自适应变化的概率发布时间同步信息,未同步节点与同步信息的发布者实现同步;主动同步方式下已同步节点停止发送同步信息,未同步节点通过发送同步请求信息的方式来实现同步.该协议能够很好地适应移动传感器网络的网络特性,在通信开销、同步收敛速度和鲁棒性方面具有较好的性能.     

Intermittent generalized synchronization in distributed autooscillatory media described by complex Ginzburg-Landau equations

The appearance of an intermittent regime at the boundary of the generalized chaotic synchronization region has been found for distributed autooscillatory systems described by the complex Ginzburg-Landau equations, which occur in the regime of spatiotemporal chaos. The type of the observed intermittent generalized synchronization behavior is established.     

Dynamical properties and synchronization of complex non-linear equations for detuned lasers

We study the dynamics and synchronization properties of a system of complex non-linear equations describing detuned lasers. These equations possess a whole circle of fixed points, while the corresponding real variable equations have only isolated fixed points. We examine the stability of their equilibrium points and determine conditions under which the complex equations have positive, negative or zero Lyapunov exponents and chaotic, quasiperiodic or periodic attractors for a wide range of parameter values. We investigate the synchronization of chaotic solutions of our detuned laser system, using as a drive a similar set of equations and applying the method of global synchronization. We find attractors whose three-dimensional projection is not at all similar to the well-known shape of the (real) Lorenz attractor. Finally, we apply complex periodic driving to the electric field equation and show that the model can exhibit a transition from chaotic to quasiperiodic oscillations. This leads us to the discovery of an exact periodic solution, whose amplitude and frequency depend on the parameters of the system. Since this solution is stable for a wide range of parameter values, it may be used to control the system by entraining it with the applied periodic forcing.     

Minimum steering node set of complex networks and its applications to biomolecular networks

Many systems of interests in practices can be represented as complex networks. For biological systems, biomolecules do not perform their functions alone but interact with each other to form so‐called biomolecular networks. A system is said to be controllable if it can be steered from any initial state to any other final state in finite time. The network controllability has become essential to study the dynamics of the networks and understand the importance of individual nodes in the networks. Some interesting biological phenomena have been discovered in terms of the structural controllability of biomolecular networks. Most of current studies investigate the structural controllability of networks in notion of the minimum driver node sets (MDSs). In this study, the authors analyse the network structural controllability in notion of the minimum steering node sets (MSSs). They first develop a graph‐theoretic algorithm to identify the MSS for a given network and then apply it to several biomolecular networks. Application results show that biomolecules identified in the MSSs play essential roles in corresponding biological processes. Furthermore, the application results indicate that the MSSs can reflect the network dynamics and node importance in controlling the networks better than the MDSs.Inspec keywords: molecular biophysics, biocontrol, graph theoryOther keywords: graph‐theoretic algorithm, MSS, minimum driver node sets, structural controllability, network dynamics, network controllability, biological systems, biomolecular networks, complex networks, minimum steering node set     

基于非漏电脉冲耦合振荡器模型的无线传感器网络时间同步算法

提出了一种基于非漏电脉冲耦合振荡器模型的无线传感器网络(WSNs)时间同步算法,并对算法的正确性进行了证明,给出了算法步骤的描述.同时分析了如何在WSN节点上实现该算法,引入了不应期来解决由于延迟带来的节点之间重复激发问题,并讨论了模型中各参数对同步的影响.非漏电脉冲耦合振荡器模型采用线性的动态函数描述振荡器的状态变化...     

Generalized methodology for modeling and simulating optical interconnection networks using diffraction analysis

Research in the field of free-space optical interconnection networks has reached a point where simulators and other design tools are desirable for reducing development costs and for improving design time. Previously proposed methodologies have only been applicable to simple systems. Our goal was to develop a simulation methodology capable of evaluating the performance characteristics for a variety of different free-space networks under a range of different configurations and operating states. The proposed methodology operates by first establishing the optical signal powers at various locations in the network. These powers are developed through the simulation by diffraction analysis of the light propagation through the network. After this evaluation, characteristics such as bit-error rate, signal-to-noise ratio, and system bandwidth are calculated. Further, the simultaneous evaluation of this process for a set of component misalignments provides a measure of the alignment tolerance of a design. We discuss this simulation process in detail as well as provide models for different optical interconnection network components.     

Nonlinear complex behaviour of TCP in UMTS networks and performance analysis

Nonlinear dynamic behaviour of transmission control protocol (TCP) in universal mobile telecommunications system (UMTS) networks is proposed. The dynamic characteristics of TCP are explored using the fundamentals of chaos theory, and the occurrence of chaotic behaviour in relation to the feedback that is received (packet drops, packet delays) by TCP from the network is explained theoritically. To validate the concept proposed, a model of the UMTS network is built and simulated under various user traffic loads. Using standard chaos methodology, it was found that inside the UMTS the TCP exhibits aperiodicity and sensitivity to initial conditions that are inherent characteristics of chaos. In particular, simulation results illustrate that as the traffic load increases, the behaviour of the network ranges from periodically stable to chaotic, with a direct impact on the quality of service of the network.     

The diminishing role of hubs in dynamical processes on complex networks

It is notoriously difficult to predict the behaviour of a complex self-organizing system, where the interactions among dynamical units form a heterogeneous topology. Even if the dynamics of each microscopic unit is known, a real understanding of their contributions to the macroscopic system behaviour is still lacking. Here, we develop information-theoretical methods to distinguish the contribution of each individual unit to the collective out-of-equilibrium dynamics. We show that for a system of units connected by a network of interaction potentials with an arbitrary degree distribution, highly connected units have less impact on the system dynamics when compared with intermediately connected units. In an equilibrium setting, the hubs are often found to dictate the long-term behaviour. However, we find both analytically and experimentally that the instantaneous states of these units have a short-lasting effect on the state trajectory of the entire system. We present qualitative evidence of this phenomenon from empirical findings about a social network of product recommendations, a protein–protein interaction network and a neural network, suggesting that it might indeed be a widespread property in nature.