3,404 research outputs found
Communities and classes in symmetric fractals
Two aspects of fractal networks are considered: the community structure and
the class structure, where classes of nodes appear as a consequence of a local
symmetry of nodes. The analysed systems are the networks constructed for two
selected symmetric fractals: the Sierpinski triangle and the Koch curve.
Communities are searched for by means of a set of differential equations.
Overlapping nodes which belong to two different communities are identified by
adding some noise to the initial connectivity matrix. Then, a node can be
characterized by a spectrum of probabilities of belonging to different
communities. Our main goal is that the overlapping nodes with the same spectra
belong to the same class
Combinatorial aspect of fashion
Simulations are performed according to the Axelrod model of culture
dissemination, with modified mechanism of repulsion. Previously, repulsion was
considered by Radillo-Diaz et al (Phys. Rev. E 80 (2009) 066107) as dependent
on a predefined threshold. Here the probabilities of attraction and repulsion
are calculated from the number of cells in the same states. We also investigate
the influence of some homogeneity, introduced to the initial state. As the
result of the probabilistic definition of repulsion, the ordered state
vanishes. A small cluster of a few percent of population is retained only if in
the initial state a set of agents is prepared in the same state. We conclude
that the modelled imitation is successful only with respect to agents, and not
only their features
Heavy context dependence---decisions of underground soldiers
An attempt is made to simulate the disclosure of underground soldiers in
terms of theory of networks. The coupling mechanism between the network nodes
is the possibility that a disclosed soldier is going to disclose also his
acquaintances. We calculate the fraction of disclosed soldiers as dependent on
the fraction of those who, once disclosed, reveal also their colleagues. The
simulation is immersed in the historical context of the Polish Home Army under
the communist rule in 1946-49.Comment: 7 pages, 5 figures, for the European Conference on Modelling and
Simulation (ECMS 2015
If others jump to the queue front, how long I will wait?
Two models of a queue are proposed: a human queue and two lines of vehicles
before a narrowing. In both models, a queuer tries to evaluate his waiting
time, taking into account the delay caused by intruders who jump to the queue
front. As the collected statistics of such events is very limited, the
evaluation can give very long times. The results provide an example, when
direct observations should be supplemented by an inference from the context.Comment: 4 pages, 3 figure
Parametrisation of F_2^gamma at low Q^2 and of sigma(gamma,gamma) and sigma(gamma^*,gamma) at high energies
A parametrisation of the real photon structure function F_2^gamma in the low
Q^2, low x region is formulated. It includes both the VMD and the QCD
components, the latter suitably extrapolated to the low Q^2 region and based on
arbitrary parton distributions in the photon. The parametrisation used together
with the GRV and GRS' parton densities describes reasonably well the existing
high energy data on F_2^gamma, sigma(gamma,gamma) and the low Q^2 data on
sigma(gamma^*, gamma). Predictions for sigma(gamma,gamma) and for sigma(gamma^*
,gamma) for energies which may become accessible in future linear colliders are
also given.Comment: 21 pages, 11 figure
Situations in traffic - how quickly they change
Spatio-temporal correlations of intensity of traffic are analysed for one
week data collected in the motorway M-30 around Madrid in January 2009. We
found that the lifetime of these correlations is the shortest in the evening,
between 6 and 8 p.m. This lifetime is a new indicator how much attention of
drivers is demanded in given traffic conditions.Comment: 9 pages, 6 figure
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