Majority-vote model with a bimodal distribution of noises

We consider the majority-vote dynamics where the noise parameter, associated with each spin on a two-dimensional square lattice, is a bimodally distributed random variable defined as q$q$ with probability (1−f)$(1-f)$ or zero with probability f$f$, where 0≤f≤1$0\le f\le 1$ is the proportion of noiseless sites. We use Monte Carlo simulations and finite size scaling theory to characterize the ordered and disordered phases and study the phase transition of the model. We conclude that in the thermodynamic limit, the value of the critical noise below which there exists an ordered phase increases with f$f$, the fraction of sites with zero noise. The calculation of the critical exponents shows that the introduction of disorder in the noise parameter does not alter the Ising critical behavior of the model system.     

Minor hysteresis loops model based on exponential parameters scaling of the modified Jiles–Atherton model

In this present work, the minor hysteresis loops model based on parameters scaling of the modified Jiles–Atherton model is evaluated by using judicious expressions. These expressions give the minor hysteresis loops parameters as a function of the major hysteresis loop ones. They have exponential form and are obtained by parameters identification using the stochastic optimization method “simulated annealing”. The main parameters influencing the data fitting are three parameters, the pinning parameter k, the mean filed parameter α and the parameter which characterizes the shape of anhysteretic magnetization curve a. To validate this model, calculated minor hysteresis loops are compared with measured ones and good agreements are obtained.     

全局耦合网络上的两种类集团的聚集-湮没反应动力学

利用Monte-Carlo模拟研究了全局耦合网络上扩散限制的不可逆聚集-湮没过程的动力学行为. 在系统中, 同种类集团相遇, 将发生聚集反应; 不同种类的集团相遇, 则发生部分湮没反应. 模拟结果表明:1) 当两种粒子初始浓度相等时, 系统长时间演化后, 集团浓度c(t)和粒子浓度g(t)呈现幂律形式, c(t)～t^{- α}和g(t)～t^-β, 其中幂指数α 和β 满足α=2β 的关系, 且α=2/(2 + q); 集团大小分布随时间的演化满足标度律, a相似文献   

Hydrogen storage in different carbon materials: Influence of the porosity development by chemical activation

The hydrogen adsorption capacity of different types of carbon nanofibers (platelet, fishbone and ribbon) and amorphous carbon have been measured as a function of pressure and temperature. The results showed that the more graphitic carbon materials adsorbed less hydrogen than more amorphous materials. After a chemical activation process, the hydrogen storage capacities of the carbon materials increased markedly in comparison with the non-activated ones.BET surface area of amorphous carbon increased by a factor of 3.5 and the ultramicropore volume doubled, thus increasing the hydrogen adsorption by a factor of 2. However, BET surface area in platelet CNFs increased by a factor of 3 and the ultramicropore volume by a factor of 6, thus increasing the hydrogen storage by a factor of 4.5. The dependency of hydrogen storage capacity of carbon materials on the BET surface area was evaluated using both a condensation model and experimental results. Comparison of data suggests that the hydrogen adsorption capacity clearly depends on the pore structure and so, on the accessibility to the internal surface.     

Synchronizing chaotic systems up to an arbitrary scaling matrix via a single signal

This paper introduces a novel type of synchronization, where two chaotic systems synchronize up to an arbitrary scaling matrix. In particular, each drive system state synchronizes with a linear combination of response system states by using a single synchronizing signal. The proposed observer-based method exploits a theorem that assures asymptotic synchronization for a wide class of continuous-time chaotic (hyperchaotic) systems. Two examples, involving Rössler’s system and a hyperchaotic oscillator, show that the proposed technique is a general framework to achieve any type of synchronization defined to date.     

A meshless scaling iterative algorithm based on compactly supported radial basis functions for the numerical solution of Lane‐Emden‐Fowler equation

In this article, we combine the compactly supported radial basis function (RBF) collocation method and the scaling iterative algorithm to compute and visualize the multiple solutions of the Lane‐Emden‐Fowler equation on a bounded domain Ω ? R² with a homogeneous Dirichlet boundary condition. This novel method has the advantage over traditional methods, which approximate the spatial derivatives using either the finite difference method (FDM), the finite element method (FEM), or the boundary element method (BEM), because it does not require a mesh over the domain. As a result, it needs less computational time than the globally supported RBF collocation method. When compared with the reference solutions in (Chen, Zhou, and Ni, Int J Bifurcation Chaos 10 (2000), 565–1612), our numerical results demonstrate the accuracy and ease of implementation of this method. It is therefore much more suitable for dealing with the complex domains than the FEM, the FDM, and the BEM. © 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 28: 554‐572, 2012     

基于多主体的股市模型不同市场形态下的标度行为

利用理论分析和计算机仿真相结合的方法研究一个随机多主体的股市模型,理论分析得到基础价值均衡、非基础价值均衡、周期和混沌四种市场形态的典型参数设置,基于多主体的计算机仿真产生对应参数的价格序列.对此数据的统计分析发现:股市的所有市场形态都呈现收益率分布和波动时间依赖的标度行为,其中基础价值均衡形态下收益率累积分布指数和波动时间依赖的自相似指数最大,非基础价值均衡形态下两指数最小,周期和混沌形态下居中.     

矩阵值函数空间中尺度空间的稠密性

多分辨分析的概念在小波基构造中起着非常重要的作用,并经历了从经典多分辨分析到多重多分辨分析,再到矩阵值多分辨分析的研究历程.本文基于矩阵值多分辨分析,研究并给出了矩阵值函数空间中尺度空间稠密性的两个充要条件,并在此基础之上得到了稠密性的两个充分条件.     

Extensive numerical study of the anomalous dynamic scaling of the Wolf-Villain model

In order to study the microscopic physical mechanisms of roughness surfaces exhibiting the anomalous scaling behavior, the Wolf-Villain model in 1+1 and 2+1 dimensions is investigated by the kinetic Monte-Carlo simulation on long time and large length scale (the growth time and the system size are respectively extended to t=2²⁹, for 1+1 dimensions, and t=2²¹, L×L=512×512 for 2+1 dimensions). In the 2+1-dimensional simulations, the noise reduction technique is employed so as to eliminate the crossover effects in the growth process. Our calculations show that the Wolf-Villain model in 1+1 dimensions very probably exhibits intrinsic anomalous scaling behavior in the time and length simulation range of this paper, and the 2+1-dimensional Wolf-Villain model leads to a pyramidal mounded morphology. Some properties of the mounded pattern in the 2+1-dimensional Wolf-Villain model are discussed in the final part of this presentation.     

Multiple time scale formalism and its application to long water waves

In the present work, by employing the multiple time scaling method, we studied the nonlinear waves in shallow-water problem and obtained a set of Korteweg–deVries equations governing the various order terms in the perturbation expansion. By seeking a travelling wave type of solutions for the evolution equations, we have obtained a set of wave speeds associated with each time parameter. It is shown that the speed corresponding to the lowest order time parameter given the wave speed of the conventional reductive perturbation method, whereas the wave speeds corresponding to the higher order time parameters give the speed correction terms. The result obtained here is exactly the same with that of Demiray [H. Demiray, Modified reductive perturbation method as applied to long water waves: Korteweg–deVries hierarchy, Int. J. Nonlinear Sci. 6 (2008) 11–20] who employed the modified reductive perturbation method.