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Université de Fribourg

Information filtering based on transferring similarity

Sun, Duo ; Zhou, Tao ; Liu, Jian-Guo ; Liu, Run-Ran ; Jia, Chun-Xiao ; Wang, Bing-Hong

In: Physical Review E, 2009, vol. 80, no. 1, p. 017101

n this Brief Report, we propose an index of user similarity, namely, the transferring similarity, which involves all high-order similarities between users. Accordingly, we design a modified collaborative filtering algorithm, which provides remarkably higher accurate predictions than the standard collaborative filtering. More interestingly, we find that the algorithmic performance will approach...

Université de Fribourg

Optimal view angle in collective dynamics of self-propelled agents

Tian, Bao-Mei ; Yang, Han-Xin ; Li, Wei ; Wang, Wen-Xu ; Wang, Bing-Hong ; Zhou, Tao

In: Physical Review E, 2009, vol. 79, no. 5, p. 052102

We study a system of self-propelled agents with the restricted vision. The field of vision of each agent is only a sector of disk bounded by two radii and the included arc. The inclination of these two radii is characterized by the view angle. The consideration of restricted vision is closer to the reality because natural swarms usually do not have a panoramic view. Interestingly, we find that...

Université de Fribourg

Accelerating consensus of self-driven swarm via adaptive speed

Zhang, Jue ; Zhao, Yang ; Tian, Baomei ; Peng, Liqian ; Zhang, Hai-Tao ; Wang, Bing-Hong ; Zhou, Tao

In: Physica A: Statistical Mechanics and its Applications, 2009, vol. 3888, no. 7, p. 1237-1242

In recent years, the well-developed Vicsek model has attracted more and more attention. Unfortunately, in-depth research on its convergence speed is not yet completed. In this paper, we investigate some key factors governing the convergence speed of the Vicsek model with the assistance of extensive numerical simulations. A significant phenomenon surfaces that the convergence time scales obeys a...

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

Consensus of self-driven agents with avoidance of collisions

Peng, Liqian ; Zhao, Yang ; Tian, Baomei ; Zhang, Jue ; Wang, Bing-Hong ; Zhang, Hai-Tao ; Zhou, Tao

In: Physical Review E, 2009, vol. 79, no. 2, p. 026113

In recent years, many efforts have been addressed on collision avoidance of collectively moving agents. In this paper, we propose a modified version of the Vicsek model with adaptive speed, which can guarantee the absence of collisions. However, this strategy leads to an aggregated state with slowly moving agents. We therefore further add a certain repulsion, which results in both faster...

Université de Fribourg

Structural effects on synchronizability of scale-free networks

Liu, Jian-Guo ; Zhou, Tao ; Guo, Qiang ; Wang, Bing-Hong

In: International Journal of Modern Physics C, 2008, vol. 19, no. 9, p. 1359 - 1366

In this paper, we numerically investigate the structural characteristics that affect the synchronizability of coupled identical oscillators on scale-free networks. By using the edge-exchange method, we can change the network structure with degree sequence fixed. An optimal algorithm, namely Tabu Search, is applied, respectively, to enhance and weaken the synchronizability. The numerical results...

Université de Fribourg

Personal recommendation via modified collaborative filtering

Liu, Run-Ran ; Jia, Chun-Xiao ; Zhou, Tao ; Sun, Duo ; Wang, Bing-Hong

In: Physica A: Statistical Mechanics and its Applications, 2009, vol. 388, no. 4, p. 462-468

In this paper, we propose a novel method to compute the similarity between congeneric nodes in bipartite networks. Different from the standard cosine similarity, we take into account the influence of a node’s degree. Substituting this new definition of similarity for the standard cosine similarity, we propose a modified collaborative filtering (MCF). Based on a benchmark database, we...

Université de Fribourg

Optimal contact process on complex networks

Yang, Rui ; Zhou, Tao ; Xie, Yan-Bo ; Lai, Ying-Cheng ; Wang, Bing-Hong

In: Physical Review E, 2008, vol. 78, no. 6, p. 066109

Contact processes on complex networks are a recent subject of study in nonequilibrium statistical physics and they are also important to applied fields such as epidemiology and computer and communication networks. A basic issue concerns finding an optimal strategy for spreading. We provide a universal strategy that, when a basic quantity in the contact process dynamics, the contact probability...

Université de Fribourg

Scale invariance of human electroencephalogram signals in sleep

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

In: Physical Review E, 2007, vol. 76, p. 061903

In this paper, we investigate the dynamical properties of electroencephalogram (EEG) signals of humans in sleep. By using a modified random walk method, we demonstrate that scale-invariance is embedded in EEG signals after a detrending procedure is applied. Furthermore, we study the dynamical evolution of the probability density function (PDF) of the detrended EEG signals by nonextensive...

Université de Fribourg

Modeling human dynamics with adaptive interest

Han, Xiao-Pu ; Zhou, Tao ; Wang, Bing-Hong

In: New Journal of Physics, 2008, vol. 10, p. 073010

Increasing recent empirical evidence indicates the extensive existence of heavy tails in the inter-event time distributions of various human behaviors. Based on the queuing theory, the Barabási model and its variations suggest the highest-priority-first protocol to be a potential origin of those heavy tails. However, some human activity patterns, also displaying heavy-tailed temporal statistics,...