【摘要】 建立了被动多轴差分吸收光谱层析系统,实现烟羽气体的时空浓度分布测量,分别采用传统的同步迭代重建算法(SIRT)和改进的SIRT对测量数据进行了重建分析,克服了一些实际测试中不能获取大量投影数据或投影分布不均匀、存在噪声的问题,精确地重建出大气痕量气体的二维空间分布.在不同的模型及评价指标下,通过数值模拟对两种重建算法的效果进行比较,改变改进的SIRT算法中的松弛因子,在5500次的迭代过程中,指标d从0.435降到了0.044,指标r从0.376降到了0.044,改进的SIRT算法具有更好的重建效果.外场重建试验中成功重建了大气痕量气体的二维空间.更多还原

【Abstract】 Optical tomography system based on modified simultaneous iterative reconstruction technique is designed to real-time monitor spatial distribution and diffusion process of smoke plume in a power plant.Concentration profiles,rather than just a point value,of smoke plume concentrations are the goal of this method,and the tomography algorithm is analyzed.According to incomplete projection data in the process of reconstruction and exiting noise interference,the modified simultaneous iterative reconstruction technique(SIRT) is adopted to extract the information of the trace gas concentration by a fan beam scanning and is compared to the conventional SIRT.Three evaluation indexes show that the reconstruction effect is the best by choosing proper relaxation factor,which reduces the index d to 0.044 from 0.435 and reduces the index r to 0.044 from 0.376 for 5500 iterations.Hence,the modified algorithm performs better in estimating the shape of the plume,this method is used to process the measured spectra in field campaign,the reconstruction results and the measured data are basically consistent,which is further confirmed by the experimental results.更多还原