小波变换-差分吸收光谱法在NO气体浓度反演过程中的研究  

Study on wavelet transform in the process of NO concentration inversion

作　　者：贾英新[1] 姚鹏辉 庞增拴[1] 王勇[1] JIA Ying-xin;YAO Peng-hui;PANG Zeng-shuan;WANG Yong(Hebei Mechatronics Intermediate Pilot Production Base,Shijiazhuang Hebei 050000,China)

机构地区：[1]河北省机电一体化中试基地,河北石家庄050000

出　　处：《河北省科学院学报》2018年第1期11-17,共7页Journal of The Hebei Academy of Sciences

摘　　要：差分吸收光谱法通过快变("窄带"高频)分子特征吸收部分来区别微量气体种类。在实际的测量中由于系统噪声信号叠加在吸收光谱上,进而影响测量结果。差分吸收光谱法较为常见的去噪分析方法为多项式拟合平滑滤波的方式,因此提出在不影响原有差分吸收光学密度细节的基础上采用小波变换-差分吸收光谱法进行逐层解析去噪。首先,利用软阈值小波去噪处理随波长在0上下波动的差分光学密度曲线,然后取绝对值求其绝对面积积分。不同气体浓度的差分吸收光学密度的面积积分不同,以此建立浓度反演方程,提高了反演精度。对于本系统而言采用db4母小波的小波母函数和一层分解层数效果最好。The differential absorption spectrum is used to distinguish the trace gas species by means of fast changing(narrow band,high frequency)molecular characteristic absorption components.In the actual measurement due to the system noise signal superimposed on the absorption spectra,and then affect the measurement results.Differential absorption spectroscopy usually uses polynomial fitting and smoothing filtering to deal with noise.Therefore,wavelet transform is proposed to reduce noise in this paper.The differential absorption optical density of the measured gas is a fluctuation curve of 0 at the upper and lower levels by soft threshold wavelet denoising,and then take the absolute value and the area integral.The area integral of difference absorption optical density of different gas concentration is different,so the concentration inversion equation is established and the inversion accuracy is improved.For this system,the wavelet parent function and the number of layers decomposed by db4 wavelet are the best.

关 键 词：差分吸收光谱法 小波变换 去噪 NO 浓度 

分 类 号：TH741[机械工程—光学工程]