Performance of third-order ghost imaging with second-order intensity correlation

The third-order ghost imaging with the second-order intensity correlation is theoretically and experimentally demonstrated.The resolution and visibility of the reconstructed image are discussed,and the relationship between resolution and visibility is analyzed.The theoretical results show that a tradeoff exists between the visibility and resolution of the reconstructed image;the better the image resolution,the worse the image visibility.Numerical simulations are carried out to verify this theory,and a ghost...     

Modified adaptive algebraic tomographic reconstruction of gas distribution from incomplete projection by a two-wavelength absorption scheme

A modified adaptive algebraic reconstruction technique (MAART) with an auto-adjustment relaxation parameter and smoothness regularization is developed to reveal the tomographic reconstruction of H 2 O distribution in combustion from incomplete projections. Determinations of relaxation parameter and regularization factor are discussed with regard to the consideration of improvement in reconstruction and reduction of computational burden. A two-wavelength scheme from tunable diode laser absorption measurement, 7444.36 and 7185.59 cm 1 , is used to simplify the nonlinear solution problem for obtaining the tomographic distributions of concentration and temperature simultaneously. Results of calculations demonstrate that MAART can perform the reconstruction results more efficiently with little complex modification and much lower iterations as compared with the traditional algebraic reconstruction technique (ART) or simultaneous iterative reconstruction technique (SIRT) methods. The stability of the algorithm is studied by reconstruction from projections with random noise at different levels to demonstrate the dependence of reconstruction results on precise line-of-sight measurements.     

无零级衍射干扰的彩色数字全息研究

彩色数字全息研究中,用球面波为重建波及角谱衍射公式进行波前重建是一种有效的方法.然而,重建图像上通常伴有强烈的零级衍射干扰.本文通过理论分析,对波前重建过程作了重要改进.用改进后的方法进行彩色数字全息的实验研究表明,重建彩色图像的质量获得显著改善. 关键词： 彩色数字全息 波前重建 零级衍射干扰     

一种测量多相流流型的ECT图像重建算法

提出了一种新的电容层析成像图像重建算法-IMNSNOF算法.该算法在分析极小范数解的基础之上针对ECT逆问题的特点对其进行改进,并利用奇异值分解定理证明这种改进的数值稳定作用.在此基础上建立新的日标泛函,并在求解该泛函的过程中采用正则技巧对其进行改进确保数值解的稳定性.利用非闭合电极ECT传感器实测了多相流沿流向的流型...     

中子半影成像的计算机断层重建技术

实际用于中子半影成像重建的方法都是线性方法,而计算机断层重建是一种能够用于中子半影成像重建的新方法.介绍了中子半影成像的断层重建原理,将半影成像的诊断图像沿径向等角度提取、微分后就可以使用断层重建方法重建.给出了使用卷积反投影方法重建不同噪声诊断图像的结果,并分析了断层重建的优缺点.重建结果表明,断层重建方法能够重建出...     

Simulation of ion beam extraction and focusing system

The characteristics of ion beam extraction and focused to a volume as small as possible were investigated with the aid of computer code SIMION 3D version 7. This has been used to evaluate the extraction characteristics (accel-decel system) to generate an ion beam with low beam emittance and high brightness. The simulation process can provide a good study for optimizing the extraction and focusing system of the ion beam without any losses and transported to the required target. Also, a study of a simulation model for the extraction system of the ion source was used to describe the possible plasma boundary curvatures during the ion extraction that may be affected by the change in an extraction potential with a constant plasma density meniscus.     

Convergence results of Landweber iterations for linear systems

The Landweber scheme is a method for algebraic image reconstructions. The convergence behavior of the Landweber scheme is of both theoretical and practical importance. Using the diagonalization of matrix, we derive a neat iterative representation formula for the Landweber schemes and consequently establish the convergence conditions of Landweber iteration. This work refines our previous convergence results on the Landweber scheme.     

一类Reinhardt域的Bergman核函数零点的边界性质

本文研究了形如E_p={(ω,z)∈C~(1+n):|ω|~(2p)+‖z‖~21}p∈R~+的一类Reinhardt域,并针对非陆启铿域E_p探讨其Bergman核函数零点的边界性质,即给出了域E_p×E_p的不同类型边界的邻域内是否存在Bergman核函数零点的判别方法.     

Existence and Nonexistence of Weak Positive Solution for a Class of p-Laplacian Systems

In this work, we are interested to obtain some result of existence and nonex- istence of positive weak solution for the following p-Laplacian system
{-△piui=λifi（u1,^…,um）,inΩ, i=1,...,m, ui=0,
on δΩ,Vi=1,…,m,
where △piz = div（｜△z｜^pi-2△Z）, Pi ≥ 1,λi,1 ≤ i ≤ m are a positive parameter, and Ω is a bounded domain in IR^N with smooth boundary δΩ. The proof of the main results is based to the method of sub-supersolutions.