用相位恢复方法测量多孔光纤的三维折射率分布

结合计算机断层成像方法，提出了一种新的相位恢复显微测量实验技术.应用该技术测量了多孔光纤的三维折射率分布.这种技术是基于强度传递方程的理论，对相位的测量是直接的，测量对光纤无损害.这是一种测量多孔光纤的三维折射率分布的有效方法. 关键词： 断层法 相位恢复 显微测量 多孔光纤     

核技术的医学应用

 自30年代起医学上就已开始应用原子核来治疗疾病,到了60年代核医学进入发展阶段,80年代开展了γ照相和放射性核素发射计算机断层摄影术,进行了体外竞争放射分析法的各项实验,由此进入了现代核医学的高级发展阶段。核医学是研究放射性核素及其辐射线的医学应用、医学理论基础的新兴学科。     

基于Radon逆变换的相对平行直线扫描CT解析重建

计算机断层成像(CT)技术广泛应用于医学诊断、工业检测等领域.近年来,提出了一种相对平行直线扫描CT(PTCT),采取射线源-探测器对物体作相对平行直线移动的扫描方式来采集数据,其结构简单、应用灵活、成本低.针对PTCT图像重建,提出了一种基于Radon逆变换的解析重建算法(PTCT-DHB).相比于经典的PTCT滤波...     

In-vivo fluorescence molecular tomography based on optimal small animal surface reconstruction

Accurate small animal surface reconstruction is important for full angle non-contact fluorescence molecular tomography （FMT） systems. In this letter, an optimal surface reconstruction method for FMT is proposed. The proposed method uses a line search method to minimize the mismatch between the reconstructed three- dimensional （3D） surface and the projected object silhouette at different angles. The results show that the mean mismatches of the 3D surfaces generated on three live anesthetized mice are all less than two charge coupled device （CCD） pixels （0.154 mm）. With the accurately reconstructed 3D surface, in-vivo FMT is also performed.     

Photon-Measurement Density Function of Fluorescence Molecular Tomography Based on Direct Method

Photon-measurement density function （PMDF）, which is the kernel of fluorescence molecular tomography （FMT）, largely determines the accuracy of reconstruction result of FMT. Based on the direct method, we propose an expression of PMDF in FMT, which is derived from the finite element method （FEM） solution of the diffusion equation. Compared with the traditional expression based on the perturbation method, the accuracy of expression based on the direct method is shown in theory. Lastly the reconstruction results of phantoms prove this accuracy in experiment.     

内蒙古卡休他他铁矿断层泥近红外光谱学特征及意义

内蒙古卡休他他铁矿是一个矽卡岩型磁铁矿床,矿区内有多组成矿后期发育的断层。本研究采用近红外光谱(NIR)分析技术对矿区内地下,地表断层泥以及地表土壤进行分析,通过矿物特征峰鉴定发现地下断层泥主要成分为镁铁质矿物,地表断层泥成分为硅铝质矿物,而地表土壤成分则两者兼有之。三组样品的成分分析结果都与采样地的地质背景一致。研究表明,鉴于矿化区内断层泥的主要成分为断层活动形成的粘土及其他早期成矿期的蚀变矿物,近红外光谱分析技术十分适用于此类样品,利用近红外光谱分析,一方面可鉴定断层泥中粘土矿物,进一步推测粘土的蚀变原岩成分。另一方面有也可鉴别成矿期蚀变矿物的种类,从而对热液矿床的研究提供有用的信息。     

Coherent addition of gratings for chirped-pulse-amplified lasers based on near-field and far-field measurements

The development of phased-array grating compressor is a crucial issue for high-energy,ultra-short pulse petawatt-class lasers.Almost all systems have adopted a tiled-grating approach to meet the size requirements for the compression gratings.We present a computer-control test system utilizing near-field interference and far-field focusing capable of monitoring and fast correcting tiled errors of the grating compressor.In this system,the tilt/tip errors between the two gratings are determined by the Fourier transform (FT) of the individual interference fringe,and the piston errors are determined by the ratio of the two primary peaks formed in the far-field pattern as a function of the piston difference.Monochromatic grating phasing is achieved experimentally and pulse compression is demonstrated with a tiled grating system.     

基于变分自编码器的眼科光学相干断层成像图像生成

提出了一种基于变分自编码器的眼科光学相干断层成像(OCT)图像生成方法,缓解了深度学习任务中数据不足的问题,有助于提高眼科疾病辅助诊断算法的性能.搭建了基于变分自编码器的OCT图像生成网络,并基于目前两个公开的视网膜OCT图像数据集,构建了老年性黄斑变性、糖尿病性黄斑水肿和正常三种类别的视网膜OCT图像样本数据集,并分...     

青海乐都断层气氡的年变异常特征分析

在地震预报研究中,断层气观测具有重要意义。以青海乐都断层气氡的观测资料为基础,结合该测点的环境变化特征、地球化学特征、震例等及其机理分析,认为乐都断层气氡在门源6.4级地震前有较好的前兆指示意义。2017年,因附近河道施工改造,影响断层气的运移路径,引起观测数据年形态改变。这些现象表明,该测点位于构造活动敏感部位,具有较好的映震效能,当异常出现时,排除环境及观测系统干扰后,可作为震情跟踪的重要依据。     

An improvement of the Peierls equation by taking into account the lattice effects

An improvement of the Peierls equation has been made by including the lattice effects. By using the non-trivially gluing mechanism for the simple cubic lattice, in which atoms interact with its first and second nearest neighbours through a central force, the dislocation equation has been derived rigorously for the isotropic case. In the slowly varying approximation, the Peierls equation with the improvement by including the lattice effects has been obtained explicitly. The new equation can be used to substitute for the old one in theoretical investigations of dislocations. The major change of the predicted dislocation structure is in the core region. The width of the dislocation given by using the new equation is about three times that given by the classical Peierls--Nabarro theory for the simple cubic lattice.