超声层析成像监测气／液两相泡状流体分布

综述了绕射、反射和透射３种不同模式超声层析成像系统的原理及在气／液两相流体分布状况监测中的应用现状，说细论述了透射模式ＵＣＴ系统在气／液两个泡状流体分布状况实时监测应用中的理论描述、系统构成及算法实现。最后，在仿真研究和实验研究的基础上论述了ＵＣＴ系统的发展和应用前景。     

基于卷积神经网络及有限元仿真的电容层析成像图像重建

为求解电容层析成像(electrical capacitance tomography,ECT)图像重建非线性病态逆问题,提出基于一维卷积神经网络(one-dimensional convolutional neural network,1D CNN)的电容层析成像图像重建算法.通过1D CNN建立了ECT系统独立测量...     

The subducted slab of Yangtze Continental block beneath the Tethyan orogen in western Yunnan

The western Yunnan area is a natural laboratory with fully developed and best preserved Tethyan orogen in the world. Seismic tomography reveals a slab-like high velocity anomaly down to 250 km beneath the western Yunnan Tethyan orogen, to its west there is a low-velocity column about 300 km wide. in the region from Lancangjiang to Mojiang an obvious low velocity in the lower crust and uppermost mantle overlies on the slab. Synthesizing the available geological and geochemical results, the present paper demonstrates that this slab-like high velocity anomaly is a part of the subducted plate of Yangtze Continental segment after the closure of Paleotethys. The collision of India and Eurasia continent starting from 50-60 MaBP might trigger thermal disturbance in the upper mantle and cause the uprising of asthenosphere, in that case the subducted Yangtze plate could be broken off, causing Cenozoic magmatic activities and underplating in the Lancangjiang-Mojiang region.     

Automatic data acquisition system and reconstruction algorithm for computerized ionospheric tomography

The design and operation features of the automatic data acquisition system for the low-latitude ionospheric tomography along the 120°E meridian are presented. The system, automatically collects the differential Doppler phase data, and GPS satellite beacon signal is simultaneously collected to achieve time synchronization of all recelvers in whole station-chain. An improved reconstruction algorithm of computerized ionospheric tomography is also proposed, in which calculating of the integral phase constant and choosing of the initial guess are integrated in the procedure of reconstruction and evaluated by the reconstructed image. Both numerical simulation examples and reconstructed results from observed data show that the new algorithm works reasonably and effectively with ionospheric CT problems. Foundation item: Supported by the National Natural Science Foundation of China (49584006) Biography: WU Xiong-bin (1968-), male, Ph. D candidate. Research direction: computerized ionospheric tomography.     

重力场中概率成像方法对脉状矿体的识别

重力场概率成像方法对复杂地质体的成像效果较差,提出一种较好的适用于脉状矿体模型的改进方法．把重力异常场看作位于脉状矿体顶点的点源产生的场,从而把对脉状矿体的成像转换成对脉状矿体的顶点成像,并根据顶点推断脉状矿体的几何参数．脉状矿体的正反演结果表明。这种方法是可行的．     

Narrow-band tomographic radar imaging of precession cone targets

The principle and method of the narrow-band tomo-graphic radar imaging (NBTRI) of the precession cone target are studied. Firstly, the motion model and electromagnetic scattering characteristics of the precession cone target are introduced. Secondly, based on the traditional NBTRI algorithm, a novel narrow-band tomography clean radar imaging (NBTCRI) algorithm is proposed to enhance the image quality of NBTRI results. In addition, the resolution performance of the NBTRI algorithm is analyzed. Finally, based on the ideal scattering point model, this paper discusses the relationship between the precession angle and the estimated target size from NBTRI results. By using the target’s chamber data, NBTRI and NBTCRI results of the precession cone target are further analyzed, which indicates the effectiveness of the proposed method.     

Data-Domain Wave Equation Reflection Traveltime Tomography

Estimation of an accurate macro velocity model plays an important role in seismic imag-ing and model parameter inversion. Full waveform inversion (FWI) is the classical data-domain inver-sion method. H...     

Region of Interest Imaging for a General Trajectory with the Rebinned BPF Algorithm

The back-projection-filtration(BPF) algorithm has been applied to image reconstruction for cone-beam configurations with general source trajectories.The BPF algorithm can reconstruct 3-D region-of-interest(ROI) images from data containing truncations.However,like many other existing algorithms for cone-beam configurations,the BPF algorithm involves a back-projection with a spatially varying weighting factor,which can result in the non-uniform noise levels in reconstructed images and increased computation ti...     

基于张量子空间的半脑对称度特征与癫痫识别

结合脑PET图像信息,提出了一种基于张量子空间的半脑对称度特征的识别方法用于识别PET图像中癫痫病灶.首先计算全部脑PET图像中所有体素的SUV,并基于SUV建立三阶张量;然后提取半脑对称度特征,建立半脑对称度张量模型;其次利用多线性主成分分析(MPCA)方法对半脑对称度张量模型进行特征选择;最后基于支持向量机(SVM)分类器进行癫痫识别.实验结果表明:提出的算法能够有效地识别脑PET图像中的癫痫病灶,可以作为计算机辅助诊断方式帮助医生进行癫痫疾病的诊断.     

开放式电阻抗成像建模及其仿真

为克服封闭式电阻抗成像电极位置不确定性引入的图像重构误差,采用固定电极阵列的开放式电阻抗成像(open electrical impedance tomography,OEIT)模型。将求解整个开放场域电磁场边值问题,近似转化为局部的虚拟场域。通过仿真实验选取有效边界参数和电极阵列结构。利用有限元法求解OEIT的正问题,采用一步牛顿法进行图像重构。实验结果表明OEIT能够探测到目标位置、区域以及电导率的变化,重构图像较清晰。OEIT在浅层体表具有较好的分辨率和定位准确度,有一定的临床应用价值。