EMD时频分析拉曼光谱和近红外光谱  

EMD Time-Frequency Analysis of Raman Spectrum and NIR

作　　者：赵肖宇[1] 方一鸣[2] 谭峰[1] 佟亮[3] 翟哲[4] 

机构地区：[1]黑龙江八一农垦大学信息技术学院,黑龙江大庆163319 [2]燕山大学电气工程学院,河北秦皇岛066004 [3]齐齐哈尔大学通信与电子工程学院,黑龙江齐齐哈尔161006 [4]中国林业科学研究院华北林业实验中心,北京102300

出　　处：《光谱学与光谱分析》2016年第2期424-429,共6页Spectroscopy and Spectral Analysis

基　　金：黑龙江省科学基金项目(QC2015071;F201329);国家科技支撑项目(2014BAD06B01);黑龙江省教育厅科学技术研究项目(12521378;12541897)资助

摘　　要：用时频方法分析拉曼光谱和近红外光谱。经验模态分解光谱成为特征模态分量,模态分量比重计算显示拉曼光谱能量均匀分布于各个分量,而近红外光谱的低阶特征模态分量只承载了较少的原光谱有效信息。真实光谱和数值实验均显示,经验模态分解视拉曼光谱为调幅信号,具有高频能量吸附特性;视近红外光谱为调频信号,在一阶特征模态分量中可以较好实现高频窄带解调。一阶特征模态分量希尔伯特变换显示,经验模态分解拉曼光谱时易出现模态混叠现象。进一步在时频域分析玉米叶片近红外光谱,经验模态分解后截掉低能量的一、二阶分量,用剩余特征模态分量重构光谱信号,均方根误差为1.001 1,相关系数为0.981 3,两个指标反映出重构精度较高;分解趋势项表明在近红外光波段,吸光度随着波长的减小呈现递增趋势;特征模态分量的希尔伯特变换显示,657cm^(-1)是碱胁迫光谱特有频率,可作为碱胁迫光谱特征频率来辨识。This paper analyzes the Raman spectrum and Near Infrared Spectrum（NIR）with time-frequency method.The empirical mode decomposition spectrum becomes intrinsic mode functions,which the proportion calculation reveals the Raman spectral energy is uniform distributed in each component,while the NIR＇s low order intrinsic mode functions only undertakes fewer primary spectroscopic effective information.Both the real spectrum and numerical experiments show that the empirical mode decomposition（EMD）regard Raman spectrum as the amplitude-modulated signal,which possessed with high frequency adsorption property;and EMD regards NIR as the frequency-modulated signal,which could be preferably realized high frequency narrowband demodulation during first-order intrinsic mode functions.The first-order intrinsic mode functions Hilbert transform reveals that during the period of empirical mode decomposes Raman spectrum,modal aliasing happened.Through further analysis of corn leaf＇s NIR in time-frequency domain,after EMD,the first and second orders components of low energy are cut off,and reconstruct spectral signal by using the remaining intrinsic mode functions,the root-mean-square error is 1.001 1,and the correlation coefficient is 0.981 3,both of these two indexes indicated higher accuracy in re-construction;the decomposition trend term indicates the absorbency is ascending along with the decreasing to wave length in the near-infrared light wave band;and the Hilbert transform of characteristic modal component displays,657cm^（-1） is the specific frequency by the corn leaf stress spectrum,which could be regarded as characteristic frequency for identification.

关 键 词：时频分析 经验模态分解 希尔伯特变换 近红外光谱 拉曼光谱 

分 类 号：O657.3[理学—分析化学]