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Hu K.,Xiangtan University | Xiang J.,First Aeronautical Institute of the Air Force | Xu X.-K.,Dalian Nationalities University | Li H.-J.,Central University of Finance and Economics | And 2 more authors.
Pramana - Journal of Physics | Year: 2014

By revisiting the preferential attachment (PA) mechanism for generating a classical scale-free network, we propose a class of novel preferential attachment similarity indices for predicting future links in evolving networks. Extensive experiments on 14 real-life networks show that these new indices can provide more accurate prediction than the traditional one. Due to the improved prediction accuracy and low computational complexity, these proposed preferential attachment indices can be helpful for providing both instructions for mining unknown links and new insights to understand the underlying mechanisms that drive the network evolution. © Indian Academy of Sciences.

Hu X.-G.,Huangshan University | Xiang J.,First Aeronautical Institute of the Air Force | Jiao Z.,Huangshan University | Liu Y.,Xiangtan University | And 2 more authors.
Pramana - Journal of Physics | Year: 2013

The bound states of four bosons in the quantum β-Fermi-Pasta-Ulam model are investigated and some interesting results are presented using the number conserving approximation combined with the number state method. We find that the relative magnitude of anharmonic coefficient has a significant effect on forming localized energy in the model, and the wave number plays an important role in forming different bound states. The signature of the quantum breather is also set up by the square of the amplitudes of the corresponding eigenvectors in real space.

Chen M.,Northwestern Polytechnical University | Kao K.,Northwestern Polytechnical University | Tu M.,First Aeronautical Institute of the Air Force | Zhang D.,Northwestern Polytechnical University
Advanced Materials Research | Year: 2012

Anodized composite films containing n-SiC and PTFE particles are prepared on 2024 Al alloy by anodization in phosphoric acid-base electrolyte and ultrasonic impregnation and subsequent heat treatment. Results show that the oxide film microhardness increase with n-SiC content and ultrasonic impregnation time increase, the oxide film wear extent decrease with n-SiC and PTFE content increase basically. The composite films formed on optimum conditions have reduced friction coefficients and relatively high microhardness. The friction coefficient can be as small as 0.14, while the microhardness can reach as high as 429 HV, which is much better than that of an oxide film prepared under the same conditions but without adding any particles. This indicates that the synthesized composite films have good anti-wear and self-lubricating properties. © (2012) Trans Tech Publications, Switzerland.

Xiang J.,First Aeronautical Institute of the Air Force | Hu X.G.,Huangshan University | Zhang X.Y.,First Aeronautical Institute of the Air Force | Fan J.F.,First Aeronautical Institute of the Air Force | And 4 more authors.
European Physical Journal B | Year: 2012

Community detection is of considerable importance for understanding the structure and function of complex networks. Recently, many multi-resolution methods have been proposed to uncover community structures of networks at different scales. Here, different multi-resolution methods are derived from modularity using self-loop assignment schemes, and then a set of multi-resolution modularity methods of this type are presented. These methods are carefully investigated by theoretical analysis of the transition points of the multi-resolution processes and experimental tests in model networks. Compared with the degree-dependent self-loop assignment, the mean-degree-dependent self-loop assignment can quicken the disconnecting of (small) communities with small vertex degrees, and can slow down the breakup of (large) communities with large vertex degrees. Moreover, we show that all these methods will encounter a limitation which is independent of the network size: large communities will break up before small communities are revealed by increasing their resolution parameters when the distribution of community sizes is very broad. Also, the tolerance of different methods against the limitation is different. © 2012 EDP Sciences, Società Italiana di Fisica, Springer-Verlag.

Xiang J.,Changsha Medical University | Hu T.,Shandong University of Technology | Hu K.,Xiangtan University | Tang Y.-N.,Changsha Medical University | And 3 more authors.
Canadian Journal of Physics | Year: 2015

Detection of community structures in complex networks is a common challenge in the study of complex networks. Recently, various methods have been proposed to discover community structures at different scales. Here, the multiscale methods based on Potts spin model for community detection are described and compared in the analysis of community structures of several networks. We give a critical analysis of the multiscale methods, showing a kind of limitation that the methods may suffer from when the community size difference is very broad, the breakup of (large) communities will appear before the merger of (small) communities disappears. In particular, we give the explicit expressions for the critical points of the merger and breakup of communities and derive the sufficient conditions (in the form of upper limits) that indicate when the Potts model methods suffer from the limitation. We apply the theoretical results to model networks and show that the method using the configuration null model (i.e., a random graph model as comparison that has the same degree distribution as the network under study) may not recover the full structure of the model network, whereas the method using the Erdös-Rényi null model will do so. © 2015 Published by NRC Research Press.

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