1,804 research outputs found
Efficient routing on scale-free networks based on local information
In this letter, we propose a new routing strategy with a single free
parameter only based on local information of network topology. In
order to maximize the packets handling capacity of underlying structure that
can be measured by the critical point of continuous phase transition from free
flow to congestion, the optimal value of is sought out. By
investigating the distributions of queue length on each node in free state, we
give an explanation why the delivering capacity of the network can be enhanced
by choosing the optimal . Furthermore, dynamic properties right after
the critical point are also studied. Interestingly, it is found that although
the system enters the congestion state, it still possesses partial delivering
capability which do not depend on . This phenomenon suggests that the
capacity of the network can be enhanced by increasing the forwarding ability of
small important nodes which bear severe congestion.Comment: 4 pages, 7 figure
Comment on ``Scientific collaboration networks. II. Shortest paths, weighted networks, and centrality"
In this comment, we investigate a common used algorithm proposed by Newman
[M. E. J. Newman, Phys. Rev. E {\bf 64}, 016132(2001)] to calculate the
betweenness centrality for all vertices. The inaccurateness of Newman's
algorithm is pointed out and a corrected algorithm, also with O() time
complexity, is given. In addition, the comparison of calculating results for
these two algorithm aiming the protein interaction network of Yeast is shown.Comment: 3 pages, 2 tables, and 2 figure
Exact solution of gyration radius of individual's trajectory for a simplified human mobility model
Gyration radius of individual's trajectory plays a key role in quantifying
human mobility patterns. Of particular interests, empirical analyses suggest
that the growth of gyration radius is slow versus time except the very early
stage and may eventually arrive to a steady value. However, up to now, the
underlying mechanism leading to such a possibly steady value has not been well
understood. In this Letter, we propose a simplified human mobility model to
simulate individual's daily travel with three sequential activities: commuting
to workplace, going to do leisure activities and returning home. With the
assumption that individual has constant travel speed and inferior limit of time
at home and work, we prove that the daily moving area of an individual is an
ellipse, and finally get an exact solution of the gyration radius. The
analytical solution well captures the empirical observation reported in [M. C.
Gonz`alez et al., Nature, 453 (2008) 779]. We also find that, in spite of the
heterogeneous displacement distribution in the population level, individuals in
our model have characteristic displacements, indicating a completely different
mechanism to the one proposed by Song et al. [Nat. Phys. 6 (2010) 818].Comment: 4 pages, 4 figure
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