本文關鍵詞： 甲烷 光譜吸收法 經(jīng)驗模態(tài)分解 支持向量機 光子晶體光纖　出處：《燕山大學》2015年碩士論文　論文類型：學位論文

【摘要】：甲烷是大氣的主要污染物之一,嚴重危害人們的生命安全,據(jù)悉,當空氣中甲烷的濃度達到百分之十時,人體就會產(chǎn)生嚴重不適,甚至影響生命健康。因此,找到一種便捷,高效且實用的檢測甲烷濃度的方法極為重要,由經(jīng)典的郎伯-比爾定律可知,光譜吸收法對于甲烷的檢測具有其獨特的優(yōu)勢,能夠實現(xiàn)甲烷的低濃度、高精度測量。本文以光譜吸收法為主線,展開系列研究,將光路模塊設計、硬件電路模塊設計、軟件信號處理三者相銜接,依次進行研究設計,最終構成了一套完整的甲烷濃度檢測系統(tǒng)。分別對以下工作進行研究:(1)對甲烷光譜吸收理論進行分析,根據(jù)甲烷分子的性質(zhì)和光譜理論,選擇適合甲烷檢測的線性和線寬,然后根據(jù)光譜吸收波段的確定,選擇合適的光源,并進行差分式檢測的光路設計。(2)搭建整體模式的甲烷濃度檢測系統(tǒng),將它主要分為三個模塊:光路模塊、電路模塊、信號處理模塊。分別對三個模塊進行設計,利用光子晶體光纖和全反棱鏡的有效結合,設計出可實現(xiàn)氣體雙光路濃度檢測的氣室,并對接收信號進行硬件電路和軟件編程的處理,提高實驗結果的精確性。(3)將小波去噪和經(jīng)驗模態(tài)分解去噪分別應用到測量的實驗結果中,選取不同的評價指標對比它們的優(yōu)劣性,從而確定經(jīng)驗模態(tài)分解的去噪效果更優(yōu)。并且將去噪后的數(shù)據(jù)進行多次實驗分析,驗證了數(shù)據(jù)的有效性,進而驗證了系統(tǒng)的可靠性。(4)應用支持向量機神經(jīng)網(wǎng)絡實現(xiàn)甲烷濃度的等級預測,通過實驗驗證其預測的可靠性,實現(xiàn)了在不需要知道精確濃度,只需知道一定濃度范圍下的準確預測,并設計出基于GUI的甲烷濃度等級預測的人機交互界面,便于更加直觀的觀測甲烷濃度等級變化,及時采取措施,降低損失。
[Abstract]:Methane is one of the major pollutants in the atmosphere, seriously endangering the safety of people's lives. It is reported that when the concentration of methane in the air reaches 10:00, the human body will have serious discomfort and even affect the health of life. It is very important to find a convenient, efficient and practical method to detect methane concentration. According to the classical Langbo-Beer law, the spectral absorption method has its unique advantages for methane detection. In this paper, spectral absorption method is the main line, a series of research will be carried out, optical circuit module design, hardware circuit module design, software signal processing. A complete methane concentration detection system was designed in turn. The following work was studied: 1) the theory of methane spectral absorption was analyzed. According to the properties of methane molecule and spectrum theory, the linear and linewidth suitable for methane detection are selected, and then the suitable light source is selected according to the spectrum absorption band. And the differential detection of the optical path design. 2) build the overall mode of methane concentration detection system, it is mainly divided into three modules: optical circuit module, circuit module. Signal processing module. The three modules are designed respectively. Using the effective combination of photonic crystal fiber and full inverse prism, the gas chamber can be designed to detect the concentration of gas double optical path. In order to improve the accuracy of the experimental results, wavelet de-noising and empirical mode decomposition de-noising are applied to the experimental results respectively. Different evaluation indexes are selected to compare their advantages and disadvantages, so as to determine that empirical mode decomposition is more effective in de-noising, and the de-noised data are analyzed many times to verify the validity of the data. Furthermore, the reliability of the system is verified. 4) the support vector machine neural network is used to realize the prediction of methane concentration, and the reliability of the prediction is verified by experiments, and the accurate concentration is realized without knowing the exact concentration. We only need to know the accurate prediction under a certain concentration range, and design the man-machine interface of methane concentration grade prediction based on GUI, which is convenient to observe methane concentration grade change more intuitively and take measures in time. Reduce losses.
【學位授予單位】：燕山大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X84;TP274

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