Wang Wenzheng, Wang Yanming, Song Wujun, Li Xueqin
Appl Opt. 2017 Mar 20;56(9):2548-2555. doi: 10.1364/AO.56.002548.
A multiband infrared diagnostic (MBID) method for methane emission monitoring in limited underground environments was presented considering the strong optical background of gas/solid attenuation. Based on spatial distribution of aerosols and complex refractive index of dust particles, forward calculations were carried out with/without methane to obtain the spectral transmittance through the participating atmosphere in a mine roadway. Considering the concurrent attenuation and absorption behavior of dust and gases, four infrared wavebands were selected to retrieve the methane concentration combined with a stochastic particle swarm optimization (SPSO) algorithm. Inversion results prove that the presented MBID method is robust and effective in identifying methane at concentrations of 0.1% or even lower with inversed relative error within 10%. Further analyses illustrate that the four selected wavebands are indispensable, and the MBID method is still valid with transmission signal disturbance in a conventional dust-polluted atmosphere under mechanized mining condition. However, the effective detection distance should be limited within 50 m to ensure inversed relative error less than 5% at 1% methane concentration.
针对有限地下环境中甲烷排放监测问题，考虑到气体/固体衰减造成的强烈光学背景，提出了一种多波段红外诊断（MBID）方法。基于气溶胶的空间分布和粉尘颗粒的复折射率，分别在有/无甲烷的情况下进行正向计算，以获取矿井巷道中参与大气的光谱透过率。考虑到粉尘和气体的同时衰减和吸收行为，结合随机粒子群优化（SPSO）算法，选择四个红外波段来反演甲烷浓度。反演结果表明，所提出的MBID方法在识别浓度为0.1%甚至更低的甲烷时具有鲁棒性和有效性，反演相对误差在10%以内。进一步分析表明，所选的四个波段是不可或缺的，并且在机械化开采条件下传统粉尘污染大气中存在传输信号干扰时，MBID方法仍然有效。然而，有效检测距离应限制在50米以内，以确保在甲烷浓度为1%时反演相对误差小于5%。
