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Université de Fribourg

Improved collaborative filtering algorithm via information transformation

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

In: International Journal of Modern Physics C, 2009, vol. 20, no. 2, p. 285-293

In this paper, we propose a spreading activation approach for collaborative filtering (SA-CF). By using the opinion spreading process, the similarity between any users can be obtained. The algorithm has remarkably higher accuracy than the standard collaborative filtering using the Pearson correlation. Furthermore, we introduce a free parameter β to regulate the contributions of objects to...

Université de Fribourg

Effects of user's tastes on personalized recommendation

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

In: International Journal of Modern Physics C, 2009, vol. 20, no. 12, p. 1925-1932

In this paper, based on a weighted projection of the user-object bipartite network, we study the effects of user tastes on the mass-diffusion-based personalized recommendation algorithm, where a user's tastes or interests are defined by the average degree of the objects he has collected. We argue that the initial recommendation power located on the objects should be determined by both of their...

Université de Fribourg

Accurate and diverse recommendations via eliminating redundant correlations

Zhou, Tao ; Su, Ri-Qi ; Liu, Run-Ran ; Jiang, Luo-Luo ; Wang, Bing-Hong ; Zhang, Yi-Cheng

In: New Journal of Physics, 2009, vol. 11, p. 123008

In this paper, based on a weighted projection of a bipartite user-object network, we introduce a personalized recommendation algorithm, called network-based inference (NBI), which has higher accuracy than the classical algorithm, namely collaborative filtering. In NBI, the correlation resulting from a specific attribute may be repeatedly counted in the cumulative recommendations from different...

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

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

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...