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Laminar optical tomography (LOT) is a new mesoscopic functional optical imaging technique. Currently, the forward problem of LOT image reconstruction is generally solved on the basis of Monte-Carlo (MC) methods. However, considering the nonlinear nature of the image reconstruction in LOT with the increasing number of source positions, methods based on MC take too much computation time. This letter develops a fast image reconstruction algorithm based on perturbation MC (pMC) for reconstructing the absorption or scattering image of a slab medium, which is suitable for LOT or other functional optical tomography system with narrow source-detector separation and dense sampling. To calculate the pMC parameters, i.e., the path length passed by a photon and the collision numbers experienced in each voxel with only one baseline MC simulation, we propose a scheme named as the trajectory translation and target voxel regression (TT&TVR) based on the reciprocity principle. To further speed up the image reconstruction procedure, the weighted average of the pMC parameters for all survival photons is adopted and the region of interest (ROI) is extracted from the raw data to save as the prior information of the image reconstruction. The method is applied to the absorption reconstruction of the layered inhomogeneous media. Results demonstrate that the reconstructing time is less than 20 s with the X - Y section of the sample subdivided into 50 × 50 voxels, and the target size quantitativeness ratio can be obtained in a satisfying accuracy in the source-detector separations of 0.4 and 1.25 mm, respectively.  相似文献   
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建立了描述投资者心理和股票交易量的元胞自动机模型.综合零邻居、Von Neumann和Moore三种邻居形式制定不同的规则,用模糊隶属度函数刻画投资者的选择心理.模拟结果表明:自信程度系数与绝对总交易量之间呈现稳定的"倒U形"结构;信息交流程度对股市活跃程度有影响;投资者数目对市场活跃程度起关键作用.  相似文献   
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A method for the untargeted screening and quantitative analysis of drug residues in bean sprouts by ultra performance liquid chromatography-quadrupole/ orbitrap high resolution mass spectrometry (UPLC-QOrbitrap HRMS) was developed. In the process of screening, the samples were extracted by acetonitrile and the data were gathered via the full MS-ddMS2 mode. In the absence of standards, qualitative analysis was carried out according to the exact mass number of precursor ions and secondary fragment ions information combined with the database. The optimized dispersive solid-phase extraction (d-SPE) method was used to purify the samples. 9 compounds in bean sprouts were screened and quantified on the basis of the peak areas of the precursor ions. 9 compounds showed good linear relationships (R2>0.990) in the linear concentration ranges. The limits of detection of this method were between 2.0-5.0 μg/kg. The recoveries of 9 compounds at three spiked levels of 5, 10, 50 μg/kg ranged from 80.1% to 111.1%, and the relative standard deviations were less than 15%. © 2023, Youke Publishing Co.,Ltd. All rights reserved.  相似文献   
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