Report on the dynamical evolution of an axially symmetric quasar model     

N. J. Papadopoulos  N. D. Caranicolas 《Journal of Astrophysics and Astronomy》2006,27(4):389-397

The role of the angular momentum in the regular or chaotic character of motion in an axially symmetric quasar model is examined. It is found that, for a given value of the critical angular momentumL _zc , there are two values of the mass of the nucleusM _n for which transition from regular to chaotic motion occurs. The [L _zc – M _n ] relationship shows a linear dependence for the time independent model and an exponential dependence for the evolving model. Both cases are explained using theoretical arguments together with some numerical evidence. The evolution of the orbits is studied, as mass is transported from the disk to the nucleus. The results are compared with the outcomes derived for galactic models with massive nuclei.  相似文献   

智能优化LSSVM算法的混沌时间序列边坡变形预测模型     

徐南  马符讯  贾东振 《测绘与空间地理信息》2015,(2):9-11,17

边坡变形序列存在一定混沌特征,本文将混沌分析方法应用到边坡变形预测中。为解决标准LSSVM模型中惩罚参数和核函数参数因任意给定或经验给定带来的非最优问题,将遗传算法和粒子群算法引入LSSVM模型,根据变形序列建立GA-LSSVM和PSO-LSSVM预测模型,与标准LSSVM混沌预测模型和基于神经网络的混沌预测模型进行比较。结果表明,GA-LSSVM和PSO-LSSVM模型预测中误差分别为0.73 mm和0.77 mm,LSSVM,BP,RBF三种模型中误差分别为0.90 mm,0.80 mm和0.75 mm;因此,本文提出的预测模型用于边坡变形预测比其他几种模型具有更高的精度。  相似文献   

混沌蜂群优化的NSST域多光谱与全色图像融合     

吴一全  王志来 《遥感学报》2017,21(4):549-557

为有效融合多光谱图像的光谱信息和全色图像的空间细节信息,提出了一种基于混沌蜂群优化和改进脉冲耦合神经网络(PCNN)的非下采样Shearlet变换(NSST)域图像融合方法。首先对多光谱图像进行Intensity-HueSaturation(IHS)变换,全色图像的直方图按照多光谱图像亮度分量的直方图进行匹配;然后分别对多光谱图像的亮度分量和新全色图像进行NSST变换,对低频分量使用改进加权融合算法进行融合,以互信息作为适应度函数,利用混沌蜂群算法找到最优加权系数。对高频分量采用改进脉冲耦合神经网络(PCNN)方法进行融合,再经NSST逆变换和IHS逆变换得到融合图像。本文方法在主观视觉效果和信息熵、光谱扭曲度等客观定量评价指标上优于基于IHS变换、基于非下采样Contourlet变换(NSCT)和非负矩阵分解(NMF)、基于NSCT和PCNN等5种融合方法。本文方法在提升图像空间分辨率的同时,有效地保留了光谱信息。  相似文献   

A generalized two-disk dynamo model     

Sergey V. Ershov  George G. Malinetskii  Alexander A. Ruzmaikin 《地球物理与天体物理流体动力学》2013,107(1-4):251-277

Abstract

A generalized two-disk dynamo model is considered that includes mechanical friction; this model is intended to simulate in its broad character the behavior of the geodynamo. Fixed points, limit cycles and chaotic attractors are located for different input parameters of the model. The chaotic regimes are of several kinds as are the “routes to chaos”. Several approximate models, helpful for studying the dynamo are discussed. A number of essential differences from the well-known Rikitake dynamo are demonstrated.  相似文献   

Barodesy: a new hypoplastic approach   总被引：1，自引：0，他引：1  

D. Kolymbas 《国际地质力学数值与分析法杂志》2012,36(9):1220-1240

It is shown that the asymptotic mechanical behaviour (i.e. stresses asymptotically obtained with constant deformation rates) determines the entire mechanical behaviour of granular materials, such as soil. In this paper, a constitutive model, or rather a new theoretical framework, for sand is derived in terms of rational mechanics. The new theory, called ‘barodesy’, has an outstanding simplicity and comprises previously introduced concepts of Soil Mechanics: critical states and barotropy (i.e. power law dependence of stiffness on stress). Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

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栾元重  栾亨宣  马德鹏  刘娜  周岩 《大地测量与地球动力学》2013,33(5):133-135

?纣??????????硢????????????????????????????α???????????????????????????????????????db10С???????????????????????????????е???????????????С???????????????????????????????????????Lyapunov??????????????????ж???????????????????????????????????????з??????????????????????????  相似文献   

Extracting predictable components and forecasting techniques in extended-range numerical weather prediction     

WANG QiGuang  CHOU JiFan  FENG GuoLin 《中国科学:地球科学(英文版)》2014,57(7):1525-1537

This paper refers to the CNOP-related algorithms and formulates the practical method and forecast techniques of extracting predictable components in a numerical model for predictable components on extended-range scales.Model variables are divided into predictable components and unpredictable chaotic components from the angle of model prediction error growth.The predictable components are defined as those with a slow error growth at a given range.A targeted numerical model for predictable components is established based on the operational dynamical extended-range forecast(DERF)model of the National Climate Center.At the same time,useful information in historical data are combined to find the fields for predictable components in the numerical model that are similar to those for the predictable components in historical data,reducing the variable dimensions in a similar judgment process and further correcting prediction errors of predictable components.Historical data is used to obtain the expected value and variance of the chaotic components through the ensemble forecast method.The numerical experiment results show that this method can effectively improve the forecast skill of the atmospheric circulation field in the 10–30 days extended-range numerical model and has good prospects for operational applications.  相似文献   

利用混沌粒子群算法确定河流水质模型参数     

孟令群  郭建青 《西安地质学院学报》2009,(2):169-172

将混沌寻优思想引入到粒子群优化算法中,提出了混沌粒子群算法,这种方法利用混沌运动的随机性、遍历性和规律性等特性对当前粒子群体中的粒子进行混沌寻优。通过这种处理使得粒子群体的进化速度加快,从而改善了粒子群优化算法摆脱局部极值点的能力,提高了算法的收敛速度和精度。并将混沌粒子群算法应用于求解分析瞬时投放示踪剂情况下的一维河流水团示踪试验数据以及确定河流水质参数的函数优化问题,结果表明,混沌粒子群算法的收敛性能明显优于粒子群优化算法。  相似文献   

一种基于分数阶傅里叶变换的改进图像加密算法   总被引：1，自引：0，他引：1  

崔得龙  肖明  左敬龙 《成都信息工程学院学报》2010,25(1):22-25

针对目前基于分数阶傅里叶变换的图像加密算法中存在的不足,设计了一种基于分数阶傅里叶变换和混沌系统的图像加密新算法。图像加密过程分两个步骤：首先将原始图像的分数阶傅里叶变换系数经过双随机相位加密,然后利用混沌系统生成的置乱矩阵对图像进行置乱加密后得到最终的加密图像。方案的安全性依赖于随机相位掩膜、分数阶傅里叶变换阶数以及混沌系统的初始参数。理论分析和模拟实验结果表明该方案具有良好的图像加密效果。  相似文献   

Stress attractors predicted by a high-cycle accumulation model confirmed by undrained cyclic triaxial tests     

《Soil Dynamics and Earthquake Engineering》2015

  相似文献