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Université de Fribourg

Predictive protocol of flocks with small-world connection pattern

Zhang, Hai-Tao ; Chen, Michael Z. Q. ; Zhou, Tao

In: Physical Review E, 2009, vol. 79, no. 01, p. 016113

By introducing a predictive mechanism with small-world connections, we propose a new motion protocol for self-driven flocks. The small-world connections are implemented by randomly adding long-range interactions from the leader to a few distant agents, namely, pseudoleaders. The leader can directly affect the pseudoleaders, thereby influencing all the other agents through them efficiently....

Université de Fribourg

Opinion dynamics on directed small-world networks

Jiang, L. -L. ; Hua, D. -Y. ; Zhu, J. -F. ; Wang, Bing-Hong ; Zhou, Tao

In: The European Physical Journal B, 2008, vol. 65, no. 2, p. 251-255

We investigate the self-affirmation effect on formation of public opinion in a directed small-world social network. The system presents a non-equilibrium phase transition from a consensus state to a disordered state with coexistence of opinions. The dynamical behaviors are very sensitive to the density of long-range-directed interactions and the strength of self-affirmation. When the...

Université de Fribourg

Improve consensus via decentralized predictive mechanisms

Zhang, Hai-Tao ; Chen, Michael ZhiQiang ; Zhou, Tao

In: EPL Europhysics Letters, 2009, vol. 86, p. 40011

For biogroups and groups of self-driven agents, making decisions often depends on interactions among group members. In this paper, we seek to understand the fundamental predictive mechanisms used by group members in order to perform such coordinated behaviors. In particular, we show that the future dynamics of each node in the network can be predicted solely using local information provided by...

Université de Fribourg

Collective behavior coordination with predictive mechanisms

Zhang, Hai-Tao ; Chen, Michael ZhiQiang ; Stan, Guy-Bart ; Zhou, Tao ; Maciejowski, Jan M.

In: IEEE Circuits and Systems Magazine, 2008, vol. 6, no. 3, p. 67 - 85

In natural flocks/swarms, it is very appealing that low-level individual intelligence and communication can yield advanced coordinated collective behaviors such as congregation, synchronization and migration. In the past few years, the discovery of collective flocking behaviors has stimulated much interest in the study of the underlying organizing principles of abundant natural groups, which has...

Université de Fribourg

Evolution of the Internet and its cores

Zhang, Guo-Qing ; Zhang, Guo-Qiang ; Yang, Qing-Feng ; Cheng, Su-Qi ; Zhou, Tao

In: New Journal of Physics, 2008, vol. 10, p. 123027

In this paper, we empirically study the evolution of large scale Internet topology at the autonomous system (AS) level. The network size grows in an exponential form, obeying the famous Moore's law. We theoretically predict that the size of the AS-level Internet will double every 5.32 years. We apply the k-core decomposition method on the real Internet, and find that the size of a k-core with...

Université de Fribourg

Singularities and symmetry breaking in swarms

Li, Wei ; Zhang, Hai-Tao ; Chen, Michael ZhiQiang ; Zhou, Tao

In: Physical Review E, 2008, vol. 77, no. 5, p. 021920

A large-scale system consisting of self-propelled particles, moving under the directional alignment rule (DAR), can often self-organize to an ordered state that emerges from an initially rotationally symmetric configuration. It is commonly accepted that the DAR, which leads to effective long-range interactions, is the underlying mechanism contributing to the collective motion. However, in this...

Université de Fribourg

Effect of initial configuration on network-based recommendation

Zhou, Tao ; Jiang, L.-L. ; Su, R.-Q. ; Zhang, Yi-Cheng

In: Europhysics Letters, 2008, vol. 81, no. 5, p. 58004

In this paper, based on a weighted object network, we propose a recommendation algorithm, which is sensitive to the configuration of initial resource distribution. Even under the simplest case with binary resource, the current algorithm has remarkably higher accuracy than the widely applied global ranking method and collaborative filtering. Furthermore, we introduce a free parameter β to...

Université de Fribourg

Empirical study on clique-degree distribution of networks

Xiao, Wei-Ke ; Ren, Jie ; Qi, Feng ; Song, Zhi-Wei ; Zhu, Meng-Xiao ; Yang, Hong-Feng ; Jin, Hui-Yu ; Wang, Bing-Hong ; Zhou, Tao

In: Physical Review E, 2007, vol. 76, no. 3, p. 037102

The community structure and motif-modular-network hierarchy are of great importance for understanding the relationship between structures and functions. We investigate the distribution of clique degrees, which are an extension of degree and can be used to measure the density of cliques in networks. Empirical studies indicate the extensive existence of power-law clique-degree distributions in...

Université de Fribourg

Scaling behaviour and memory in heart rate of healthy human

Cai, Shi-Min ; Peng, Hu ; Yang, Hui-Jie ; Zhou, Tao ; Zhou, Pei-Ling ; Wang, Bing-Hong

In: Chinese Physics Letters, 2007, vol. 24, no. 10, p. 3002

We investigate a set of complex heart rate time series from healthy human in different behaviour states with the detrended fluctuation analysis and diffusion entropy (DE) method. It is proposed that the scaling properties are influenced by behaviour states. The memory detected by DE exhibits an approximately same pattern after a detrending procedure. Both of them demonstrate the long-range strong...

Université de Fribourg

Enhancing the network synchronizability

Zhao, Ming ; Chen, Guan-rong ; Zhou, Tao ; Wang, Bing-hong

In: Frontiers of Physics in China, 2007, vol. 2, no. 4, p. 460-468

The structural and dynamical properties, particularly the small-world effect and scale-free feature, of complex networks have attracted tremendous interest and attention in recent years. This article offers a brief review of one focal issue concerning the structural and dynamical behaviors of complex network synchronization. In the presentation, the notions of synchronization of dynamical systems...