共查询到20条相似文献,搜索用时 15 毫秒
1.
Li WANG 《Frontiers of Physics》2009,4(4):556
In this paper, we model the mobile ad hoc communication network on a two-dimensional square lattice. Both structure and function of it depend on transmission range and site-occupancy of nodes. Critical occupancies σc for different transmission ranges r to maintain global connection are found. Universal scaling function behaves as η~f(Rβσ), where R=(r−r0)/r0, and the scaling exponent β=−0.61, which distinguishes itself from percolation in previous lattice or network models. When the occupancy σ is near the threshold σc, individual nodes self-organize into a dynamic small world network relative to geometric distance. The network has a cut-off degree below which clustering coefficient keeps constant, which distinguish itself from other systems and has its potential application in technical designs. 相似文献
2.
G. Demirel R. Prizak P. N. Reddy T. Gross 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(4):541-548
The Rock-Paper-Scissors (RPS) game is a paradigmatic model for cyclic dominance in
biological systems. Here we consider this game in the social context of competition
between opinions in a networked society. In our model, every agent has an opinion which is
drawn from the three choices: rock, paper or scissors. In every timestep a link is
selected randomly and the game is played between the nodes connected by the link. The
loser either adopts the opinion of the winner or rewires the link. These rules define an
adaptive network on which the agents’ opinions coevolve with the network topology of
social contacts. We show analytically and numerically that nonequilibrium phase
transitions occur as a function of the rewiring strength. The transitions separate four
distinct phases which differ in the observed dynamics of opinions and topology. In
particular, there is one phase where the population settles to an arbitrary consensus
opinion. We present a detailed analysis of the corresponding transitions revealing an
apparently paradoxical behavior. The system approaches consensus states where they are
unstable, whereas other dynamics prevail when the consensus states are stable. 相似文献
3.
The concept of network immunity, i.e., the robustness of
the network connectivity after a random deletion of edges or
vertices, has been investigated in biological or communication
networks. We apply this concept to a self-assembling, physical
network of microemulsion droplets connected by telechelic
polymers, where more than one polymer can connect a pair of
droplets. The gel phase of this system has higher immunity if it
is more likely to survive (i.e., maintain a
macroscopic, connected component) when some of the polymers are
randomly degraded. We consider the distribution
p(σ) of the number of polymers between a pair of
droplets, and show that gel immunity decreases as the variance
of p(σ) increases. Repulsive interactions between the
polymers decrease the variance, while attractive interactions
increase the variance, and may result in a bimodal p(σ). 相似文献
4.
Hristu Culetu 《Central European Journal of Physics》2008,6(2):317-320
We take a null hypersurface (causal horizon) generated by a congruence of null geodesics as the boundary of the Doran-Lobo-Crawford
spacetime to be the place where the Brown-York quasilocal energy is located. The components of the outer and inner stress
tensors are computed and shown to depend on time and on the impact parameter b of the test-particle trajectory. The spacetime is a solution of Einstein’s equations with an anisotropic fluid as source.
The surface energy density σ on the boundary is given by the same expression as that obtained previously for the energy stored on a Rindler horizon. For
time intervals long compared to b (when the stretched horizon tends to the causal one), the components of the stress tensors become constant.
相似文献
5.
We study a generalization of the voter model on complex networks, focusing on the scaling of mean exit time. Previous work
has defined the voter model in terms of an initially chosen node and a randomly chosen neighbor, which makes it difficult
to disentangle the effects of the stochastic process itself relative to the network structure. We introduce a process with
two steps, one that selects a pair of interacting nodes and one that determines the direction of interaction as a function
of the degrees of the two nodes and a parameter α which sets the likelihood of the higher degree node giving its state to the other node. Traditional voter model behaviors
can be recovered within the model, as well as the invasion process. We find that on a complete bipartite network, the voter
model is the fastest process. On a random network with power law degree distribution, we observe two regimes. For modest values
of α, exit time is dominated by diffusive drift of the system state, but as the high-degree nodes become more influential, the
exit time becomes dominated by frustration effects dependent on the exact topology of the network. 相似文献
6.
A completely Lorentz-invariant Bohmian model has been proposed recently for the case of a system of non-interacting spinless
particles, obeying Klein-Gordon equations. It is based on a multi-temporal formalism and on the idea of treating the squared
norm of the wave function as a space-time probability density. The particle’s configurations evolve in space-time in terms
of a parameter σ with dimensions of time. In this work this model is further analyzed and extended to the case of an interaction with an external
electromagnetic field. The physical meaning of σ is explored. Two special situations are studied in depth: (1) the classical limit, where the Einsteinian Mechanics of Special
Relativity is recovered and the parameter σ is shown to tend to the particle’s proper time; and (2) the non-relativistic limit, where it is obtained a model very similar
to the usual non-relativistic Bohmian Mechanics but with the time of the frame of reference replaced by σ as the dynamical temporal parameter. 相似文献
7.
在实际的应用中,无线传感器网络常常由大量电池资源有限的传感器节点组成.如何降低网络功耗,最大化网络生存时间,是传感器网络拓扑控制技术的重要研究目标.随着传感节点的运行,节点的能量分布可能越来越不均衡,需要在考虑该因素的情况下,动态地调整节点的网络负载以均衡节点的能耗,达到延长网络生存时间的目的.该文引入博弈理论和势博弈的概念,综合考虑节点的剩余能量和节点发射功率等因素,设计了一种基于势博弈的拓扑控制模型,并证明了该模型纳什均衡的存在性.通过构造兼顾节点连通性和能耗均衡性的收益函数,以确保降低节点功耗的同时维持网络的连通性.通过提高邻居节点的平均剩余能量值以实现将剩余能量多的节点选择作为自身的邻居节点,提高节点能耗的均衡性.在此基础上,提出了一种分布式的能耗均衡拓扑控制算法.理论分析证明了该算法能保持网络的连通性.与现有基于博弈理论的DIA算法和MLPT算法相比,本算法形成的拓扑负载较重、剩余能量较小的瓶颈节点数量较少,节点剩余能量的方差较小,网络生存时间更长. 相似文献
8.
M. Schumacher 《The European Physical Journal A - Hadrons and Nuclei》2006,30(2):413-422
The t-channel contribution to the difference of electromagnetic polarizabilities of the nucleon, (α - β)t, can be quantitatively understood in terms of a σ-meson pole in the complex t-plane of the invariant scattering amplitude A
1(s, t) with properties of the σ-meson as given by the quark-level Nambu-Jona-Lasinio model (NJL). Equivalently, this quantity may
be understood in terms of a cut in the complex t-plane where the properties of the σ-meson are taken from the ππ → σ → ππ, γγ → σ → ππ and Nˉ → σ → ππ reactions. This equivalence may be understood as a sum rule where the properties of the σ-meson as predicted by
the NJL model are related to the f
0(600) particle observed in the three reactions. In the following, we describe details of the derivation of (α - β)t making use of predictions of the quark-level NJL model for the σ-meson mass.
An erratum to this article is available at . 相似文献
9.
We investigate a game-theoretic model of a social system where both the rules of the game and the interaction structure are shaped by the behavior of the agents. We call this type of model, with several types of feedback couplings from the behavior of the agents to their environment, a multiadaptive game. Our model has a complex behavior with several regimes of different dynamic behavior accompanied by different network topological properties. Some of these regimes are characterized by heterogeneous, hierarchical interaction networks, where cooperation and network topology coemerge from the dynamics. 相似文献
10.
L. H. Shang X. Li X. F. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(3):369-373
We investigate the evolution of cooperative behaviors of small-world networking agents in a snowdrift game mode, where two
agents (nodes) are connected with probability depending on their spatial Euclidean lattice distance in the power-law form
controlled by an exponent α.
Extensive numerical simulations indicate that the game dynamics crucially depends on the spatial topological structure of
underlying networks with different values of the exponent α. Especially, in the distance-independent case of α=0, the small-world
connectivity
pattern contributes to an enhancement of cooperation compared with that in
regular lattices, even for the case of having a high cost-to-benefit ratio r. However, with the increment of α>0, when r≥0.4,
the spatial distance-dependent small-world (SDSW) structure tends to inhibit the evolution of cooperation in the snowdrift
game. 相似文献
11.
K. G. Trouni V. R. Kocharyan G. R. Grigoryan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2012,47(2):87-92
The problem of Borrmann absorption (anomalous absorption) of X-rays in weakly deformed crystals is considered on the basis
of Takagi’s approach to the dynamical theory. Using wave function considerations, the attenuation of rays is represented by
exp(−σl) where the attenuation factor σ includes a parameter of the lattice deformation field. The possibility of cases σ = 0 and
even σ < 0 is discussed. 相似文献
12.
Eleni Arapaki 《Physica A》2009,388(13):2757-2761
We study the spatial prisoner’s dilemma game where the players are located on the nodes of a random scale-free network. The prisoner’s dilemma game is a powerful tool and has been used for the study of mutual trust and cooperation among individuals in structured populations. We vary the structure of the network and the payoff values for the game, and show that the specific conditions can greatly influence the outcome of the game. A variety of behaviors are reproduced and the percentage of cooperating agents fluctuates significantly, even in the absence of irrational behavior. For example, the steady state of the game may be a configuration where either cooperators or defectors dominate, while in many cases the solution fluctuates between these two limiting behaviors. 相似文献
13.
We review our recent work on the synchronization of a network of delay-coupled maps, focusing on the interplay of the network
topology and the delay times that take into account the finite velocity of propagation of interactions. We assume that the
elements of the network are identical (N logistic maps in the regime where the individual maps, without coupling, evolve in a chaotic orbit) and that the coupling
strengths are uniform throughout the network. We show that if the delay times are sufficiently heterogeneous, for adequate
coupling strength the network synchronizes in a spatially homogeneous steady state, which is unstable for the individual maps
without coupling. This synchronization behavior is referred to as ‘suppression of chaos by random delays’ and is in contrast
with the synchronization when all the interaction delay times are homogeneous, because with homogeneous delays the network
synchronizes in a state where the elements display in-phase time-periodic or chaotic oscillations. We analyze the influence
of the network topology considering four different types of networks: two regular (a ring-type and a ring-type with a central
node) and two random (free-scale Barabasi-Albert and small-world Newman-Watts). We find that when the delay times are sufficiently
heterogeneous the synchronization behavior is largely independent of the network topology but depends on the network’s connectivity,
i.e., on the average number of neighbors per node.
相似文献
14.
Yin-Wen Sun Ye Liu Shou-Wan Chen Quan Liu Jian-You Guo 《The European Physical Journal A - Hadrons and Nuclei》2012,48(2):18
Influences from different fields of mesons on the pseudospin symmetry are investigated for deformed nuclei. The energy splitting
between pseudospin partners are extracted from the relativistic mean field calculations. The results show that the σ-field contribution to the pseudospin energy splitting has nearly the same magnitude as the one obtained by the ω-field, but with opposite signs. The pseudospin energy splittings either for neutron or for protons are almost the same if
the σ-field (V
σ
) and the ω-field (V
ω
) change at the same scale. The pseudospin energy splitting depends in the same way as the nucleus binding energy of the cancellation
of these two potentials, and is controlled by the same nuclear physics scale as the potential sum V
ω
+ V
σ
In comparison with the σ- and ω-fields, it is seen that the ρ meson field produces a minor influence on the pseudospin symmetry. 相似文献
15.
James Burridge Yu Gao Yong Mao 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(1):13
We consider a group of agents playing the Hawk-Dove game. These agents have a finite memory of past interactions which they use to optimize their play. By both analytical and numerical approaches, we show that an instability occurs at a critical memory length, and we provide its characterization. We show also that when the game is stable, having a long memory is beneficial but that instability, which may be produced by excessively long memory, hands the advantage to those with shorter memories. 相似文献
16.
Interplay between topology and dynamics in the World Trade Web 总被引:1,自引:0,他引:1
D. Garlaschelli T. Di Matteo T. Aste G. Caldarelli M. I. Loffredo 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(2):159-164
We present an empirical analysis of the network formed by the trade relationships between all world countries, or World Trade Web (WTW). Each (directed) link is weighted by the amount of wealth flowing between two countries, and each country is characterized
by the value of its Gross Domestic Product (GDP). By analysing a set of year-by-year data covering the time interval 1950–2000, we show that the dynamics of all GDP
values and the evolution of the WTW (trade flow and topology) are tightly coupled. The probability that two countries are
connected depends on their GDP values, supporting recent theoretical models relating network topology to the presence of a
`hidden' variable (or fitness). On the other hand, the topology is shown to determine the GDP values due to the exchange between countries. This leads
us to a new framework where the fitness value is a dynamical variable determining, and at the same time depending on, network topology in a continuous feedback. 相似文献
17.
Stress-relaxation rates at a constant strain in A-grade nickel polycrystals has been reported to depend in a peculiar manner on the initial stress
levelσ
0 at which relaxation is allowed to start. For large grains (D>75μm),s varies withσ
0 linearly over the entire stress strain curve. For small grains (D<75μm),s-σ
0 curve undergoes a change in its slope at a critical value of plastic strainɛ, which decreases as grain size increases. The observation referred to are found to correlate well with the work-hardening
behaviour of the nickel polycrystals. 相似文献
18.
Xianyu Bo 《Physica A》2010,389(5):1105-1114
Prevailing models of the evolutionary prisoner’s game on networks always assume that agents are pursuing their own profit maximization. But the results from experimental games show that many agents have other-regarding preference. In this paper, we study the emergence of cooperation from the prisoner’s dilemma game on complex networks while some agents exhibit other-regarding preference such as inequality aversion, envious and guilty emotions. Contrary to common ideas, the simulation results show that the existence of inequality aversion agents does not promote cooperation emergence on a BA (Barabási and Albert) scale-free network in most situations. If the defection attraction is big and agents exhibit strong preference for inequality aversion, the frequency of cooperators will be lower than in situations where no inequality aversion agents exist. In some cases, the existence of the inequality agents will even induce the frequency of cooperators to zero, a feature which is not observed in previous research on the prisoner’s dilemma game when the underlying interaction topology is a BA scale-free network. This means that if an agent cares about equality too much, it will be difficult for cooperation to emerge and the frequency of cooperators will be low on BA networks. The research on the effect of envy or guilty emotions on the emergence of cooperation in the prisoner’s dilemma game on BA networks obtains similar results, though some differences exist. However, simulation results on a WS (Watts and Strogatz) small-world network display another scenario. If agents care about the inequality of agents very much, the WS network favors cooperation emergence in the prisoners’ dilemma game when other-regarding agents exist. If the agent weight on other-regarding is lowered, the cooperation frequencies emerging on a WS network are not much different from those in situations without other-regarding agents, although the frequency of cooperators is lower than those of the situation without other-regarding preference agents sometimes. All the simulation results imply that inequality aversion and its variations can have important effects on cooperation emergence in the prisoner’s dilemma game, and different network topologies have different effects on cooperation emergence in the prisoner’s dilemma game played on complex networks. 相似文献
19.
20.
The $-game 总被引:1,自引:0,他引:1
J. Vitting Andersen D. Sornette 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(1):141-145
We propose a payoff function extending Minority Games (MG) that captures the competition between agents to make money. In
contrast with previous MG, the best strategies are not always targeting the minority but are shifting opportunistically between
the minority and the majority. The emergent properties of the price dynamics and of the wealth of agents are strikingly different
from those found in MG. As the memory of agents is increased, we find a phase transition between a self-sustained speculative
phase in which a “stubborn majority” of agents effectively collaborate to arbitrage a market-maker for their mutual benefit
and a phase where the market-maker always arbitrages the agents. A subset of agents exhibit a sustained non-equilibrium risk-return
profile.
Received 5 June 2002 / Received in final form 21 November 2002 Published online 27 January 2003
RID="a"
ID="a"e-mail: sornette@unice.fr
RID="b"
ID="b"CNRS UMR7536
RID="c"
ID="c"CNRS UMR6622 相似文献