本文選題：TDLAS + SLIDT�。� 參考：《天津大學》2015年博士論文

【摘要】：近年來,隨著科技的進步及經(jīng)濟的快速發(fā)展,環(huán)境污染問題成為人們?nèi)找骊P(guān)注的話題。氣體污染作為環(huán)境污染的一個重要方面,對工業(yè)生產(chǎn)安全及人類的身體健康均構(gòu)成嚴重危害。光譜吸收技術(shù)的調(diào)諧二極管激光吸收光譜(Tunable Diode Laser Absorption Spectroscopy,TDLAS)技術(shù)與波長調(diào)制/諧波檢測技術(shù)相結(jié)合,以其響應時間短、探測靈敏度高、高穩(wěn)定性等諸多優(yōu)點,被廣泛應用于有毒有害氣體濃度檢測。本文基于TDLAS技術(shù),提出軟件鎖相方法代替硬件鎖相,并對軟件鎖相方法中涉及的數(shù)學模型及算法進行理論和實驗研究。對系統(tǒng)進行儀器化設(shè)計,能夠?qū)O、CO_2和CH4氣體濃度、溫度和壓強進行同時檢測,實現(xiàn)了氣體傳感系統(tǒng)的多氣體、多參量混合傳感。本文的主要創(chuàng)新性工作如下:1、基于TDLAS氣體濃度檢測理論,本文提出了軟件鎖相的TDLAS氣體濃度檢測系統(tǒng)理論模型,理論分析了調(diào)制深度、調(diào)制頻率、相移和系統(tǒng)噪聲對軟件鎖相得到的二次諧波幅值的影響,通過仿真和理論推導得到了軟件鎖相系統(tǒng)最優(yōu)調(diào)制參數(shù)理論值。2、基于針對非平穩(wěn)非線性信號進行時域分解的經(jīng)驗模態(tài)分解(EMD)理論,本文提出了一種EMD-FCR算法用于系統(tǒng)信號去噪,以提高系統(tǒng)檢測精度。將本算法與其他常用濾波算法進行了比較,結(jié)果表明,本算法大大提高了解調(diào)信號的信噪比,將系統(tǒng)的檢測下限從原來的18ppm降低到2ppm,降低近一個數(shù)量級。3、針對氣體吸收線存在部分重疊的現(xiàn)象,本文構(gòu)建了重疊光譜擬合的數(shù)學模型,提出了一種重疊光譜分離算法,用于分離CO和CO_2的重疊光譜,實現(xiàn)了單個DFB激光器電流調(diào)諧下的CO和CO_2兩種混合氣體濃度的同時檢測。4、本文提出基于氣體吸收線線寬的溫度和壓強測量的方法。通過測量不同溫度和壓強下氣體吸收線線寬,即可推算出待測氣體的溫度和壓強。結(jié)合上述同時對多種氣體檢測研究,以及氣體的溫度和壓強檢測方法研究,本文對多種混合氣體、多參量進行同時檢測,實現(xiàn)了基于軟件鎖相的混合式傳感。
[Abstract]:In recent years, with the progress of science and technology and the rapid development of economy, environmental pollution has become a topic of increasing concern. As an important aspect of environmental pollution, gas pollution poses serious harm to industrial production safety and human health. The tunable Diode Laser Absorption Spectroscopy (TDLAS) technique combined with wavelength modulation / harmonic detection technology has many advantages, such as short response time, high detection sensitivity, high stability and so on. It is widely used to detect the concentration of toxic and harmful gases. In this paper, based on TDLAS technology, the software phase-locking method is proposed to replace the hardware phase-locked method, and the mathematical model and algorithm involved in the software phase-locking method are studied theoretically and experimentally. The instrument design of the system can simultaneously detect the concentration, temperature and pressure of COC _ 2 and Ch _ 4 gas, and realize the multi-gas and multi-parameter mixed sensing of the gas sensing system. The main innovative work of this paper is as follows: 1. Based on the TDLAS gas concentration detection theory, this paper presents a theoretical model of the software phase-locked TDLAS gas concentration detection system. The effect of phase shift and system noise on the second harmonic amplitude obtained by software phase-locked, Based on the empirical mode decomposition (EMD) theory of time-domain decomposition for non-stationary nonlinear signals, an EMD-FCR algorithm is proposed for system signal denoising. In order to improve the system detection accuracy. The algorithm is compared with other common filtering algorithms. The results show that the signal-to-noise ratio of demodulated signal is greatly improved. The detection limit of the system is reduced from the original 18ppm to 2 ppm, and the detection limit is reduced by nearly one order of magnitude. 3. Aiming at the phenomenon of partial overlap of gas absorption lines, a mathematical model of overlapping spectral fitting is constructed, and an overlapping spectral separation algorithm is proposed. The overlapping spectrum of CO and CO _ 2 is used to separate CO and CO _ 2, and the concentration of CO and CO _ 2 mixed gas in a single DFB laser is detected simultaneously. A method of measuring temperature and pressure based on the line width of gas absorption line is presented in this paper. By measuring the line width of the gas absorption line at different temperatures and pressures, the temperature and pressure of the gas to be measured can be calculated. Combined with the research of gas detection and the temperature and pressure detection methods, the mixed sensing based on software phase locking is realized in this paper.
【學位授予單位】：天津大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：X831;O433.51

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