13,435 research outputs found
Critical dynamics of the Potts model: short-time Monte Carlo simulations
We calculate the new dinamic exponent of the 4-state Potts model,
using short-time simulations. Our estimates and obtained by following the behavior of the
magnetization or measuring the evolution of the time correlation function of
the magnetization corroborate the conjecture by Okano et. al. In addition,
these values agree with previous estimate of the same dynamic exponent for the
two-dimensional Ising model with three-spin interactions in one direction, that
is known to belong to the same universality class as the 4-state Potts model.
The anomalous dimension of initial magnetization
is calculated by an alternative way that mixes two different initial
conditions. We have also estimated the values of the static exponents
and . They are in complete agreement with the pertinent results of the
literature.Comment: 12 pages, 7 figure
QoS Recommendation in Cloud Services
As cloud computing becomes increasingly popular, cloud providers compete to offer the same or similar services over the Internet. Quality of service (QoS), which describes how well a service is performed, is an important differentiator among functionally equivalent services. It can help a firm to satisfy and win its customers. As a result, how to assist cloud providers to promote their services and cloud consumers to identify services that meet their QoS requirements becomes an important problem. In this paper, we argue for QoS-based cloud service recommendation, and propose a collaborative filtering approach using the Spearman coefficient to recommend cloud services. The approach is used to predict both QoS ratings and rankings for cloud services. To evaluate the effectiveness of the approach, we conduct extensive simulations. Results show that the approach can achieve more reliable rankings, yet less accurate ratings, than a collaborative filtering approach using the Pearson coefficient
Effects of Contrarians in the Minority Game
We study the effects of the presence of contrarians in an agent-based model
of competing populations. Contrarians are common in societies. These
contrarians are agents who deliberately prefer to hold an opinion that is
contrary to the prevailing idea of the commons or normal agents. Contrarians
are introduced within the context of the Minority Game (MG), which is a binary
model for an evolving and adaptive population of agents competing for a limited
resource. Results of numerical simulations reveal that the average success rate
among the agents depends non-monotonically on the fraction of
contrarians. For small , the contrarians systematically outperform the
normal agents by avoiding the crowd effect and enhance the overall success
rate. For high , the anti-persistent nature of the MG is disturbed and
the few normal agents outperform the contrarians. Qualitative discussion and
analytic results for the small and high regimes are also
presented, and the crossover behavior between the two regimes is discussed.Comment: revtex, 11 pages, 4 figure
Dynamics of opinion formation in a small-world network
The dynamical process of opinion formation within a model using a local
majority opinion updating rule is studied numerically in networks with the
small-world geometrical property. The network is one in which shortcuts are
added to randomly chosen pairs of nodes in an underlying regular lattice. The
presence of a small number of shortcuts is found to shorten the time to reach a
consensus significantly. The effects of having shortcuts in a lattice of fixed
spatial dimension are shown to be analogous to that of increasing the spatial
dimension in regular lattices. The shortening of the consensus time is shown to
be related to the shortening of the mean shortest path as shortcuts are added.
Results can also be translated into that of the dynamics of a spin system in a
small-world network.Comment: 10 pages, 5 figure
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