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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,...

Université de Fribourg

Enhanced synchronizability via age-based coupling

Lu, Yu-Feng ; Zhao, Ming ; Zhou, Tao ; Wang, Bing-Hong

In: Physical Review E, 2007, vol. 76, p. 057103

In this Brief Report, we study the synchronization of growing scale-free networks. An asymmetrical age-based coupling method is proposed with only one free parameter α. Although the coupling matrix is asymmetric, our coupling method could guarantee that all the eigenvalues are non-negative reals. The eigenratio R will approach 1 in the large limit of α

Université de Fribourg

Opinion spreading with mobility on scale-free networks

Guo, Qiang ; Liu, Jian-Guo ; Wang, Bing-Hong ; Zhou, Tao ; Chen, Xing-Wen ; Yao, Yu-Hua

In: Chinese Physics Letters, 2008, vol. 25, no. 2, p. 773-775

A continuum opinion dynamic model is presented based on two rules. The first one considers the mobilities of the individuals, the second one supposes that the individuals update their opinions independently. The results of the model indicate that the bounded confidence ∈c, separating consensus and incoherent states, of a scale-free network is much smaller than the one of a...

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...