首页|大气介质红外辐射场混沌与分形特征

大气介质红外辐射场混沌与分形特征

扫码查看
大气介质是红外光学的重要传播媒介,也是影响红外动态信号检测与追踪的复杂背景.与固、液态介质相对稳定的性质相比,大气介质具有动态复杂性与长期不可预测性,阻碍了将其他领域成功的波动技术(如弹性波成像与反演、量子场波函数等)引入大气电磁波场,故传统经典物理学理论无法精确刻画此类复杂系统问题.但自然界此类场中产生的无序性与随机性通常可用分形的概念来阐述.利用风云4A气象卫星记录的红外云图,以水汽-二氧化碳波段的红外辐射波场为例,选取云图上任一无规时间序列,计算分形维度为分数与最大Lyapunov指数为正,初步判断大气介质红外辐射场具有混沌特征,也证明红外辐射场的动力学行为是有限自由度控制的动态非线性不规则行为.根据排列熵参数取值范围(0.87,0.92)趋于1判定,风云4A涵盖0.45~13.8 μm波段的全红外数据显示强混沌性,且混沌强度分布具有空间不均匀性.本项工作既为利用混沌特性来研究动目标及背景杂波动态演化机理、捕捉时敏微扰信号以及对水陆空红外辐射场进行中长期非线性预测等提供了理论前提;也为建立大气红外辐射场的非保守耗散方程,刻画传输介质特性以及研究宏观与微观传播机理等基本问题奠定了实验基础.
Chaotic and fractal characteristics of infrared electromagnetic wavefield in the media of atmosphere
Chaotic dynamics is a significant systematic feature of infrared electromagnetic wavefields that requires further study.Understanding the chaotic dynamics of infrared radiation wavefields can lead to advancements in high-performance detection,imaging,and recognition of weak,moving,time-varying signals.To extract the time series of the dynamic sys-tem,we have established a 4D time-space observing system.We then use the FFT transform on a random time series of frequency-band infrared data to obtain the fractional Brownian motion dimension,indicating a fractal structure in the at-mospheric infrared radiation wavefield.By using time-delay analysis,we construct a dimensional phase space and com-pute the fractal dimension.We also observe that the first Lyapunov exponent remains positive in different phase spaces,leading to the initial conclusion that the atmospheric infrared wavefield is chaotic.To measure the chaotic strength of real cases in the time-space domain,we use the permutation entropy.These results serve as a foundation for further research,such as understanding the dynamic evolution mechanism of moving objects and their background wavefields,capturing time-varying signals,and making long-term nonlinear predictions of infrared wave behaviors in different domains.

chaosLyapunov exponentsfractal dimensioncorrelation dimensionpermutation entropy

徐文君、孙胜利、刘高睿

展开 >

中国科学院上海技术物理研究所 智能红外感知重点实验室,上海 200083

混沌 Lyapunov指数 分形维度 相关维度 排列熵

万人计划领军人才项目中国科学院引才计划-B类人才项目

2024

红外与毫米波学报
中国光学学会 中国科学院上海技术物理所

红外与毫米波学报

CSTPCD北大核心
影响因子:0.612
ISSN:1001-9014
年,卷(期):2024.43(2)
  • 22