3,245 research outputs found
Simulation of Consensus Model of Deffuant et al on a Barabasi-Albert Network
In the consensus model with bounded confidence, studied by Deffuant et al.
(2000), two randomly selected people who differ not too much in their opinion
both shift their opinions towards each other. Now we restrict this exchange of
information to people connected by a scale-free network. As a result, the
number of different final opinions (when no complete consensus is formed) is
proportional to the number of people.Comment: 7 pages including 3 figs; Int.J.MOd.Phys.C 15, issue 2; programming
error correcte
Development of advanced composite structures
Composite structure programs: the L-1011 Advanced Composite Vertical Fin (ACVF), the L-1011 Advanced Composite Aileron, and a wing study program were reviewed. These programs were structured to provide the technology and confidence for the use of advanced composite materials for primary and secondary structures of future transport aircraft. The current status of the programs is discussed. The results of coupon tests for both material systems are presented as well as the ACVF environmental (moisture and temperature) requirements. The effect of moisture and temperature on the mechanical properties of advanced composite materials is shown. The requirements set forth in the FAA Certification Guidelines for Civil Composite Aircraft Structures are discussed as they relate to the ACVF
Universality of the Threshold for Complete Consensus for the Opinion Dynamics of Deffuant et al
In the compromise model of Deffuant et al., opinions are real numbers between
0 and 1 and two agents are compatible if the difference of their opinions is
smaller than the confidence bound parameter \epsilon. The opinions of a
randomly chosen pair of compatible agents get closer to each other. We provide
strong numerical evidence that the threshold value of \epsilon above which all
agents share the same opinion in the final configuration is 1/2, independently
of the underlying social topology.Comment: 8 pages, 4 figures, to appear in Int. J. Mod. Phys. C 15, issue
Los hermanos Goujaud Bonpland: dos enfoques complementarios del conocimiento botánico
French botanists of the late eighteenth and early nineteenth centuries deeply influenced the discovery and description of plant diversity in the Neotropics. Most of them studied medicine or pharmacy, for which systematics and comparative morphology played an extremely important role in the comprehension of useful plants. Some of them took courses by the most renowned European botanists and later themselves became the foremost scientists in charge of naming the plant diversity of most American countries. This article highlights the major contributions of the Goujaud Bonpland brothers to botany and describes the different ways they influenced the natural sciences at a local, regional and planetary scale.Los botánicos franceses de finales del siglo XVIII y principios del siglo XIX influenciaron profundamente el descubrimiento y la descripción de la diversidad vegetal que alberga la región Neotropical. La mayoría de estos botánicos realizaron estudios de medicina o farmacia, en el marco de los cuales la sistemática y la morfología comparativa jugaron un rol muy importante en la comprensión de la utilidad de las plantas. De esta manera, algunos de ellos tomaron cursos impartidos por los más reconocidos botánicos europeos y se convirtieron posteriormente en importantes investigadores a cargo de la identificación de la diversidad vegetal de la mayoría de los países americanos. La presente contribución pone en evidencia el aporte de los hermanos Goujaud Bonpland y describe las diferentes maneras en las que influenciaron los estudios de ciencias naturales a nivel local, regional y mundial
Number of spanning clusters at the high-dimensional percolation thresholds
A scaling theory is used to derive the dependence of the average number
of spanning clusters at threshold on the lattice size L. This number should
become independent of L for dimensions d<6, and vary as log L at d=6. The
predictions for d>6 depend on the boundary conditions, and the results there
may vary between L^{d-6} and L^0. While simulations in six dimensions are
consistent with this prediction (after including corrections of order loglog
L), in five dimensions the average number of spanning clusters still increases
as log L even up to L = 201. However, the histogram P(k) of the spanning
cluster multiplicity does scale as a function of kX(L), with X(L)=1+const/L,
indicating that for sufficiently large L the average will approach a finite
value: a fit of the 5D multiplicity data with a constant plus a simple linear
correction to scaling reproduces the data very well. Numerical simulations for
d>6 and for d=4 are also presented.Comment: 8 pages, 11 figures. Final version to appear on Physical Review
Do language change rates depend on population size?
An earlier study (Nettle 1999b) concluded, based on computer simulations and
some inferences from empirical data, that languages will change the more slowly
the larger the population gets. We replicate this study using a more complete
language model for simulations (the Schulze model combined with a
Barabasi-Albert net- work) and a richer empirical dataset (the World Atlas of
Language Structures edited by Haspelmath et al. 2005). Our simulations show
either a weak or stronger dependence of language change on population sizes
depending on the parameter settings, and empirical data, like some of the
simulations, show a weak dependence.Comment: 20 pages including all figures for a linguistic journa
Anomalous quantum glass of bosons in a random potential in two dimensions
We present a quantum Monte Carlo study of the "quantum glass" phase of the 2D
Bose-Hubbard model with random potentials at filling . In the narrow
region between the Mott and superfluid phases the compressibility has the form
with and vanishing or
very small. Thus, at the system is either incompressible (a Mott glass)
or nearly incompressible (a Mott-glass-like anomalous Bose glass). At stronger
disorder, where a glass reappears from the superfluid, we find a conventional
highly compressible Bose glass. On a path connecting these states, away from
the superfluid at larger Hubbard repulsion, a change of the disorder strength
by only changes the low-temperature compressibility by more than four
orders of magnitude, lending support to two types of glass states separated by
a phase transition or a sharp cross-over.Comment: Published version including supplementary material, 11 pages total,
15 figure
The Krause-Hegselmann Consensus Model with Discrete Opinions
The consensus model of Krause and Hegselmann can be naturally extended to the
case in which opinions are integer instead of real numbers. Our algorithm is
much faster than the original version and thus more suitable for applications.
For the case of a society in which everybody can talk to everybody else, we
find that the chance to reach consensus is much higher as compared to other
models; if the number of possible opinions Q<=7, in fact, consensus is always
reached, which might explain the stability of political coalitions with more
than three or four parties. For Q>7 the number S of surviving opinions is
approximately the same independently of the size N of the population, as long
as Q<N. We considered as well the more realistic case of a society structured
like a Barabasi-Albert network; here the consensus threshold depends on the
outdegree of the nodes and we find a simple scaling law for S, as observed for
the discretized Deffuant model.Comment: 12 pages, 6 figure
Monte Carlo Simulation of Deffuant opinion dynamics with quality differences
In this work the consequences of different opinion qualities in the Deffuant
model were examined. If these qualities are randomly distributed, no different
behavior was observed. In contrast to that, systematically assigned qualities
had strong effects to the final opinion distribution. There was a high
probability that the strongest opinion was one with a high quality.
Furthermore, under the same conditions, this major opinion was much stronger
than in the models without systematic differences. Finally, a society with
systematic quality differences needed more tolerance to form a complete
consensus than one without or with unsystematic ones.Comment: 8 pages including 5 space-consuming figures, fir Int. J. Mod. Phys. C
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