45,029 research outputs found
Distributed parameter estimation in unreliable sensor networks via broadcast gossip algorithms
In this paper, we present an asynchronous algorithm to estimate the unknown parameter under an unreliable network which allows new sensors to join and old sensors to leave, and can tolerate link failures. Each sensor has access to partially informative measurements when it is awakened. In addition, the proposed algorithm can avoid the interference among messages and effectively reduce the accumulated measurement and quantization errors. Based on the theory of stochastic approximation, we prove that our proposed algorithm almost surely converges to the unknown parameter. Finally, we present a numerical example to assess the performance and the communication cost of the algorithm.This work was supported in part by the National Natural Science Foundation of China under Grant 61503308 and Grant 61472331, in part by the Natural Science Foundation Project of Chongqing CSTC 2015jcyjA40043, and in part by Fundamental Research Funds for the Central Universities under Grant SWU114036. This publication was made possible by NPRP grant #4-1162-1-181 from the Qatar National Research Fund (a member of Qatar Foundation)
Promote cooperation by localised small-world communication
The emergence and maintenance of cooperation within sizable groups of
unrelated humans offer many challenges for our understanding. We propose that
the humans' capacity of communication, such as how many and how far away the
fellows can build up mutual communications, may affect the evolution of
cooperation. We study this issue by means of the public goods game (PGG) with a
two-layered network of contacts. Players obtain payoffs from five-person public
goods interactions on a square lattice (the interaction layer). Also, they
update strategies after communicating with neighbours in learning layer, where
two players build up mutual communication with a power law probability
depending on their spatial distance. Our simulation results indicate that the
evolution of cooperation is indeed sensitive to how players choose others to
communicate with, including the amount as well as the locations. The tendency
of localised communication is proved to be a new mechanism to promote
cooperation.Comment: 6 pages, 4 figure
Superconductivity and Phase Diagram in (LiFe)OHFeSeS
A series of (LiFe)OHFeSeS (0 x 1)
samples were successfully synthesized via hydrothermal reaction method and the
phase diagram is established. Magnetic susceptibility suggests that an
antiferromagnetism arising from (LiFe)OH layers coexists with
superconductivity, and the antiferromagnetic transition temperature nearly
remains constant for various S doping levels. In addition, the lattice
parameters of the both a and c axes decrease and the superconducting transition
temperature T is gradually suppressed with the substitution of S for Se,
and eventually superconductivity vanishes at = 0.90. The decrease of T
could be attributed to the effect of chemical pressure induced by the smaller
ionic size of S relative to that of Se, being consistent with the effect of
hydrostatic pressure on (LiFe)OHFeSe. But the detailed
investigation on the relationships between and the crystallographic
facts suggests a very different dependence of on anion height from
the Fe2 layer or -Fe2- angle from those in FeAs-based superconductors.Comment: 6 pages, 6 figure
Enhancing Transport Efficiency by Hybrid Routing Strategy
Traffic is essential for many dynamic processes on real networks, such as
internet and urban traffic systems. The transport efficiency of the traffic
system can be improved by taking full advantage of the resources in the system.
In this paper, we propose a dual-strategy routing model for network traffic
system, to realize the plenary utility of the whole network. The packets are
delivered according to different "efficient routing strategies" [Yan, et al,
Phys. Rev. E 73, 046108 (2006)]. We introduce the accumulate rate of packets,
{\eta} to measure the performance of traffic system in the congested phase, and
propose the so-called equivalent generation rate of packet to analyze the
jamming processes. From analytical and numerical results, we find that, for
suitable selection of strategies, the dual- strategy system performs better
than the single-strategy system in a broad region of strategy mixing ratio. The
analytical solution to the jamming processes is verified by estimating the
number of jammed nodes, which coincides well with the result from simulation.Comment: 6 pages, 3 figure
Promotion of cooperation induced by nonlinear attractive effect in spatial Prisoner's Dilemma game
We introduce nonlinear attractive effects into a spatial Prisoner's Dilemma
game where the players located on a square lattice can either cooperate with
their nearest neighbors or defect. In every generation, each player updates its
strategy by firstly choosing one of the neighbors with a probability
proportional to denoting the attractiveness of the
neighbor, where is the payoff collected by it and
(0) is a free parameter characterizing the extent of the nonlinear
effect; and then adopting its strategy with a probability dependent on their
payoff difference. Using Monte Carlo simulations, we investigate the density
of cooperators in the stationary state for different values of
. It is shown that the introduction of such attractive effect
remarkably promotes the emergence and persistence of cooperation over a wide
range of the temptation to defect. In particular, for large values of ,
i.e., strong nonlinear attractive effects, the system exhibits two absorbing
states (all cooperators or all defectors) separated by an active state
(coexistence of cooperators and defectors) when varying the temptation to
defect. In the critical region where goes to zero, the extinction
behavior is power law-like , where the
exponent accords approximatively with the critical exponent
() of the two-dimensional directed percolation and depends
weakly on the value of .Comment: 7 pages, 4 figure
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