用正交光路全息干涉CT技术重建电弧等离子体三维温度场

本文利用正交光路全息干涉技术和计算机有限角层析算法,借助电弧等离子体物理方程,对非对称电弧等离子体三维温度场的诊断进行了研究.     

浓度场测量的差分吸收光谱CT技术

提出了一种新的用于浓度场测量的差分吸收光谱CT技术。利用差分吸收原理进行浓度场多方位积分测量,采用少数投影最大熵重建算法进行层析图像重建。数值模拟结果表明,在0°～180°视场范围内,在4个不同的投影视角方向获取投影数据的条件下,能有效地重建出待测场分布。该技术具有较高的重建精度和良好的抗噪声性能。     

An acyclic days-off scheduling problem

This paper studies the days off scheduling problem when the demand for staffing fluctuates from day to another and when the number of total workdays is fixed in advance for each employee. The scheduling problem is then to allocate rests to employees with different days off policies: (1) two or three consecutive days off for each employee per week and (2) at least three consecutive days off for each employee per month. For each one, we propose a polynomial time algorithm to construct a solution if it exists. Received: April 2005 / Revised version: October 2005 AMS classification: 60K25, 60K30     

Mapping an underground rock mass by anisotropic acoustical transmission tomography

This paper briefly describes an acoustical transmission traveltime tomography method to simultaneously account for the anisotropy and heterogeneity of media. This method is applied to real data gathered at the rock wall of an underground plant in southwest China. The anisotropic tomograms reveal the rock wall features, which coincide well with the site observations, and provide very useful information for the evaluation and reinforcement of the rock wall.     

Experimental investigation of liquid chromatography columns by means of computed tomography

The efficiency of packed chromatographic columns was investigated experimentally by means of computed tomography (CT) techniques. The measurements were carried out by monitoring tracer fronts in situ inside the chromatographic columns. The experimental results were fitted using the equilibrium dispersive model (EDM) and varying the so called apparent axial dispersion coefficient. The additivity of the first and second central moments was exploited to estimate column efficiency in different regions of the column. The results showed that the columns under investigation offered a higher column efficiency in the centre compared to the wall region. Furthermore the void fraction in the vicinity of the walls was lower than that in the column core. For this reason the bands were conveyed faster in the central region of the column where the permeability was higher. This result is in good agreement with earlier findings.     

遥感傅里叶变换红外光谱层析技术中的重构算法

在遥感傅里叶变换红外光谱层析技术中，对于是否能够快速、经济地得出气体空间浓度分布图及预测浓度峰位置，重构算法的选择是至重要的。理想的重构算法即使在仪器噪声较大、存在测量误差、光线数量少以及待测气体在空间的分布不稳定情况下，也能够通过有限的测量数据和非对称的光线构型，得出理想的重构图。本文对遥感傅里叶变换红外光谱层析技术中采用的几种重构算法，如ART法、MART法、SIRT法和SBFM法等，作了扼要描述。与传统的ART法相比，MART法在迭代速度和迭代精度上有较大的优越性，SIRT法克服了采用代数重构技术所带来的模糊性，SBFM法使重构结果噪声明显减小。     

大型试件的X射线CT检测方法探讨

当对投影长度大于探测器长度的大型试件做平行光束CT时 ,可以认为投影被截断了。从数学上讲 ,这种情况下的解析法重建如滤波反投影法是不适宜的。然而从工程应用上来说 ,这又不是绝对的。就几种情况讨论了通过补充假数据 ,通过在 0～ 2π范围内对试件成像得到了完整的CT切片 ,获得了切片的精确重建     

Minimal Informationally Complete Measurements for Pure States

We consider measurements, described by a positive-operator-valued measure (POVM), whose outcome probabilities determine an arbitrary pure state of a D-dimensional quantum system. We call such a measurement a pure-state informationally complete (PS I-complete) POVM. We show that a measurement with 2D−1 outcomes cannot be PS I-complete, and then we construct a POVM with 2D outcomes that suffices, thus showing that a minimal PS I-complete POVM has 2D outcomes. We also consider PS I-complete POVMs that have only rank-one POVM elements and construct an example with 3D−2 outcomes, which is a generalization of the tetrahedral measurement for a qubit. The question of the minimal number of elements in a rank-one PS I-complete POVM is left open.     

Application of tomography method in millimeter wavelengths band II. Experimental

Tomographycal methods of image reconstruction of two-dimensional objects, surfaces or subsurface regions in millimeter wavelengths band are suggested and considered. Experimental images obtained using antennas and waveguiding lines of different types and radiation frequencyf≈33÷35GHz are represented. Volumetric dielectric objects and plane-parallel ferrite (or dielectric) plates distributed in free space or in homogeneous dielectric medium have been taken as objects under investigation. It is shown that in the frequency band under consideration, the images of investigated objects with characteristic dimensionA≈2λ÷7λ may be obtained by first-order diffraction tomography method (Born, Rytov or high frequency approximation of the first-order for electromagnetic field).     

Quantitative Imaging by Optical Diffraction Tomography

Optical diffraction tomography (ODT) is applied to reconstruct the cross-sectional, complex refractive index distribution of cylindrical objects. Experimental reconstructions showing noticeable image contrast for refractive index variations of about 0.001, and having a spatial resolution of about 2 μm, are obtained for objects with cross-sectional diameters of about 100 μm. The results demonstrate that ODT can be used for quantitative imaging of semitransparent fibers.Presented at the International Commission of Optics Topical Meeting, Kyoto, 1994.