6,080 research outputs found
A simple model of bank bankruptcies
Interbank deposits (loans and credits) are quite common in banking system all
over the world. Such interbank co-operation is profitable for banks but it can
also lead to collective financial failures. In this paper we introduce a new
model of directed percolation as a simple representation for contagion process
and mass bankruptcies in banking systems. Directed connections that are
randomly distributed between junctions of bank lattice simulate flows of money
in our model. Critical values of a mean density of interbank connections as
well as static and dynamic scaling laws for the statistic of avalange
bankruptcies are found. Results of computer simulations for the universal
profile of bankruptcies spreading are in a qualitative agreement with the third
wave of bank suspensions during The Great Depression in the USA.Comment: 8 pages, 6 Encapsulated Postscript figures, to be published in
Physica A (2001
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
Phase transition in hierarchy model of Bonabeau et al
The model of Bonabeau explains the emergence of social hierarchies from the
memory of fights in an initially egalitarian society. Introducing a feedback
from the social inequality into the probability to win a fight, we find a sharp
transition between egalitarian society at low population density and
hierarchical society at high population density.Comment: 3 pages including two figs.; for Int. J. Mod. Phys.
Multidimensional Consensus model on a Barabasi-Albert network
A Consensus Model according to Deffuant on a directed Barabasi-Albert network
was simulated. Agents have opinions on different subjects. A multi-component
subject vector was used. The opinions are discrete. The analysis regards
distribution and clusters of agents which are on agreement in the opinions of
the subjects. Remarkable results are on the one hand, that there mostly exists
no absolute consens. It determines depending on the ratio of number of agents
to the number of subjects, whether the communication ends in a consens or a
pluralism. Mostly a second robust cluster remains, in its size depending on the
number of subjects. Two agents agree either in (nearly) all or (nearly) no
subject. The operative parameter of the consens-formating-process is the
tolerance in change of views of the group-members.Comment: 14 pages including all 10 figures, for IJMPC 16, issue
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
Local heuristics and the emergence of spanning subgraphs in complex networks
We study the use of local heuristics to determine spanning subgraphs for use
in the dissemination of information in complex networks. We introduce two
different heuristics and analyze their behavior in giving rise to spanning
subgraphs that perform well in terms of allowing every node of the network to
be reached, of requiring relatively few messages and small node bandwidth for
information dissemination, and also of stretching paths with respect to the
underlying network only modestly. We contribute a detailed mathematical
analysis of one of the heuristics and provide extensive simulation results on
random graphs for both of them. These results indicate that, within certain
limits, spanning subgraphs are indeed expected to emerge that perform well in
respect to all requirements. We also discuss the spanning subgraphs' inherent
resilience to failures and adaptability to topological changes
Probabilistic heuristics for disseminating information in networks
We study the problem of disseminating a piece of information through all the
nodes of a network, given that it is known originally only to a single node. In
the absence of any structural knowledge on the network other than the nodes'
neighborhoods, this problem is traditionally solved by flooding all the
network's edges. We analyze a recently introduced probabilistic algorithm for
flooding and give an alternative probabilistic heuristic that can lead to some
cost-effective improvements, like better trade-offs between the message and
time complexities involved. We analyze the two algorithms both mathematically
and by means of simulations, always within a random-graph framework and
considering relevant node-degree distributions
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