第36卷，第11期 2016年11月
光谱学与光谱分析 Spectroscopy and Spectral Analysis
Vol.36,No.11,pp3752-3757
November，2016
TheApplicationofTHzSpectroscopyandGA-BP
inMethanolConcentrationDetection
TANHong-ying，ZHENGDe-zhong，LIXue，XUZheng-xia Hebei Provincial Key Laboratory on Measurement Technology and Instrumentation, School of Electrical Engineering,Yanshan University, Qinhuangdao066004, China
Abstract At ambient temperature and atmospheric pressure, making use of a photoconductive-antenna tera-hertz time-domain spectrograph and a self-designed air chamber, the terahertz timedomain spectroscopy(THz-TDS) technique test of methanol gas in the range of 0. 1~3. 0 THz shows that the methanol gas has no obvious absorption peaks in the range of 0. 1~3. 0 THz and has obvious absorption peaks in the range of o. 1~ 1. o THz. In order to improve the determination accuracy of the concentration of the methanol gas, the author detected 15 groups of methanol gas with different concentrations on the basis of the relationship between the strengths of 15 characteristic absorption peaks of different locations and the concentration of the methanol gas, and obtained the difference curve of the of the characteristic absorption peaks. Based on the function approxi-mation of BP neural network, the author optimized the initial weights and biases of the BP neural network by using the GA the genetic algorithm, which has higher rate of convergence to prevent from getting into local op timum easily, and constructed the mathematical model with the purpose of predicting the methanol gas concen tration. The test results show that the neural network is applicable to predict methanol gas in the volume con centration range of 0. 028 3~0. 424 6 m° . L1, the average relative standard deviation of the 2 sets of samples is 1. 7% , the average recovery rate is 98% , the error precision of the neural network is 101, and correlation coefficient of the measured values and the predicted values is 0. 996 77. The test basically achieved ideal predic ted results. The research results obtained experimental data of methanol gas in the terahertz frequency band and found that the method of combining terahertz time-domain spectroscopy with GA-BP neural network can effectively detect the volume concentration of methanol gas, and provided a new method for the detection of
concentration of methanol gas. Keywords
Spectroscopy; Terahertz time-domain spectroscopy: Genetic algorithm; BP neural network; Meth-
anol
中图分类号：0433
Introduction
文献标识码：A
DOI: 10.3964/i.issn. 10000593(2016)11-3752-06
when the broadband terahertz pulses are used to irradiate samples. Therefore, in recent years there are many researches scholars home and abroad used terahertz waves to detect or
Terahertz ray is in the far-infrared band, and it can real-ize nondestructive recognition for its little damage when it penetrates samples. Furthermore, because terahertz ray lo-cates between infrared spectrum and microwave, both the electromagnetic wave amplitude and phase can be acquired
Received: 2015-09-08; accepted: 2016-01-20
ganic molecules because the electromagnetic waves of this wave band can obtain the absorption spectrums of pure rota-tional transitions and vibration-rotation transitions of mole cules. For example, John C. Pearson1) et al. analyzed rota-tion spectrum in ground-state methanol, J. P. Laib[2] et al.
Foundation item: Young Scientistis Fund of the National Natural Science Foundation of China (51408528)
Biography万数据ng-ying，（1979—），female,PhD，Yanshan University
e-mail: sumeertree@163.com