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   

南洞地下河月径流时间序列的混沌特征及预测   总被引：2，自引：1，他引：1  

覃星铭  蒋忠诚  蓝芙宁  马祖陆  赵一 《中国岩溶》2015,34(4):341-347

利用基于相空间重构技术、混沌识别与预测理论对1993-2013年南洞地下河月径流时间序列的非线性特征进行了分析,由所获得的延迟时间和最佳嵌入维数实现了月径流时间序列的相空间重构,运用饱和关联维数法和小数据量法计算出南洞地下河月径流时间序列的饱和关联维数和最大Lyapunov指数,并运用Volterra模型对南洞地下河月径流时间序列进行了多步预测研究。研究结果表明,南洞地下河月径流时间序列相空间重构的延迟时间和最佳嵌入维数分别为τ=5、m=8,饱和关联维数D和最大Lyapunov指数λ分别为4.63、0.748 9,从定性和定量的角度证明了南洞地下河月径流时间序列具有弱混沌特征。Volterra自适应滤波模型的预测结果能较好地表征南洞地下河月径流的变化趋势和规律,对18个月内的短期预测精度较高,模拟效果较好。   相似文献   

On particle trajectories in restricted 3-body problem including the effect of radiation: Sun-Jupiter system     

M. K. Das  Pankaj Narang  M. Yuasa  L. M. Saha 《Astrophysics and Space Science》2008,314(1-3):59-71

In this work, we have simulated orbits of a particle moving in gravitational field of the Sun-Jupiter system. The effect of solar radiation pressure, including Poynting Robertson drag, on the evolution of particle orbits in phase space have been studied for different values of the parameter β ₁ (the ratio of radiation to gravitational force) and initial conditions. Characteristics of various computed trajectories have been studied using wavelet transform (WT), Fourier transform (FT) and Poincare surface of section method. We use wavelet analysis to identify transitions of a trajectory in time-frequency plane and further apply it to classify it as regular or chaotic in phase space. Unlike the Fourier transform method (FT), we observe that the wavelet transform (WT) also provides a basis to identify ‘sticky’ trajectories in the present dynamical system.  相似文献   

大气湍流的混沌吸引子特征   总被引：7，自引：2，他引：5  

李昕  胡非  刘罡 《气候与环境研究》2001,6(1):58-66

采用时间延迟技术,利用高性能的超声风温仪和红外湿度脉动仪所测得的大气湍流脉动资料,重构相空间中的湍流吸引子,估算了其相关维D2和最大Lyapunov指数λ1。结果表明,在不同地点、不同时间以及不同大气稳定度条件下,大气湍流的最大Lyapunov指数λ1均大于零,说明大气湍流的确具有混沌特征,且存在低维奇怪吸引子,其维数在3～7之间,视变量的不同(动力变量还是非动力变量)而不同,且受大气稳定度影响。首次使用了湍流动能来重建湍流吸引子。  相似文献   

基于三维混沌序列的DEM置乱与还原方法     

仲浩宇  王中元  李安波 《测绘通报》2019,(5):64-71

DEM是地形的真实表达,蕴含着丰富的地理空间信息。如何保证涉密DEM在网络环境中的安全传输是当前亟待解决的关键问题之一。本文采用三维混沌序列,对DEM文件先后进行高程置乱、位置置乱和文件头置乱,可使置乱后的数据失去高程变化的空间连续性与数值连续性。置乱数据经网络传输后,接收方仅凭用户密钥就可以实现置乱DEM数据的无损、盲式还原。基于ASCII格式DEM的置乱与还原试验表明:本文方法可以有效破坏原始DEM数据的空间形态特征和空间连续性,并具有较高的安全性。此外,在无原始数据参与的情况下,用户可以将置乱数据恢复至初始形态,且不会造成任何精度损失。本文算法特性基本满足了DEM数据在安全传输、封装存储等方面的应用需求。  相似文献   

Relationship between social stability and climate change in the Tang Dynasty     

Wang Xiao-Qing  Zhang David D  Pei Qing  Zhang Sheng-Da  Li Teng 《古地理学报》1999,22(2):385-396

This paper quantitatively divides the Tang Dynasty into five prosperous and chaotic social periods,and discusses the relationship between the social division and climate change. The criteria for determining prosperity and chaos is refered to a set of systematic war data. In order to verify the reasonableness of the division,we applied 1-way-ANOVA to test the differences of each variable index between prosperity and chaos periods. The results of social division are as follows: from AD 618 to AD 626,and from AD 743 to AD 784,as well as from AD 860 to AD 907 were the chaotic periods;while from AD 627 to A0 742,and from AD 785 to AD 859 were the prosperous periods. The results of 1-way-ANOVA show that,climate change,general wars,rebellions,offensive border wars,defensive border wars,agricultural harvests,and population growth rates are all significantly different between prosperity and chaos,except the general external wars. War data were used to quantitatively represent the social changes in the Tang Dynasty. In chaotic periods,the main types of wars are rebellions and defensive border wars,while the main type of wars in prosperous periods are offensive border wars. To explore the relationship between climate change and social division means to make clear the relationship between climate change and wars. The results of correlation analysis show the decrease of agricultural harvest due to lower temperature and less precipitation leads to the shortage of resources supply,so that the likelihood of rebellions increase;while during the warm periods with abundant rainfall,increasing agricultural harvest stimulates rapid population growth. Due to the limitations of technology and land resources,offensive border wars for expansion are more likely to occur.  相似文献   

A Symplectic Mapping Model as a Tool to Understand the Dynamics of 2/1 Resonant Asteroid Motion     

John D. Hadjidemetriou 《Celestial Mechanics and Dynamical Astronomy》1999,73(1-4):65-76

We present a 3-D symplectic mapping model that is valid at the 2:1 mean motion resonance in the asteroid motion, in the Sun-Jupiter-asteroid model. This model is used to study the dynamics inside this resonance and several features of the system have been made clear. The introduction of the third dimension, through the inclination of the asteroid orbit, plays an important role in the evolution of the asteroid and the appearance of chaotic motion. Also, the existence of the secondary resonances is clearly shown and their role in the appearance of chaotic motion and the slow diffusion of the elements of the orbit is demonstrated. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

甜水海钻孔TS95若干地球化学指标的非线性分析与意义   总被引：1，自引：0，他引：1  

周厚云  朱照宇  李世杰  李炳元  向明菊  余素华 《湖泊科学》2001,13(2):97-102

应用关联维分析和R／S分析对西昆伦甜水海孔TS95的4项指标（FeO,Fe2O3,Fe2O3/FeO和有机碳）进行分析,发现它们存在明显的混沌特征和Hurst现象,4项指标的混沌吸引子分别为：FeO－2．8;Fe2O3－3．2;Fe2O／FeO－2．9;有机碳2．5,饱和嵌入维数为5到6,表明控制该地区气候环境演化的动力系统是由有限维数确定的混沌系统,构筑该系统所需变量至少3到4个,最多5到6个,这种体上与深海氧同位素比较接近,与黄土剖面一些指标差异较大,4项指标折Hurst指数（FeO－0．85;Fe2O3－0．76;Fe2O3／FeO－0．65;有机碳－0．74）显示该地区气候环境演化存在明显的持续性成分,这与早期的研究一致,很可能与青藏高原的构造抬升有关,表明除了全球性气候环境波动背景外,局域性因素,如肝藏高原构造抬升和未海地区水系变迁,都会在各种气候环境演化的替代性指标上有所反映。4项指标Hurst指数的差异可能反映FeO容易迁移,受到了流域水系变化的影响,因而有机碳和Fe2O3可能是反映这种环境演化持续性分更好的指标。  相似文献   

分数阶混沌系统与整数阶混沌系统之间的同步   总被引：1，自引：0，他引：1  

周平  邝菲 《海洋学报》2010,32(10):6851-6858

基于追踪控制的思想,利用分数阶系统稳定性理论,实现了分数阶混沌系统与整数阶混沌系统之间的混沌同步,给出了补偿器和反馈控制器的选择方法. 以三维分数阶Chen系统和三维整数阶Lorenz混沌系统之间的混沌同步为例进行了数值仿真和电路仿真. 研究表明了该同步方法的有效性.  相似文献