Determination of the shape of a binary object of a square with a square hole by means of chosen initial phases

The binary object treated is a square with a square hole. We first use a set of initial phases to determine the symmetry of the object. The initial image has the gross shape of a square with a square hole, and preserves symmetry of the object. With another set of initial phases, the initial image has gross shape of a square with a hole. Sayre's equation is applied to refine this gross shape. After iterations, the result shows a square with a distorted square hole. These three squares have approximately same edge lengths. These squares are larger than the object. The holes are smaller than the hole of the object. The initial phases or the gross shapes can be used as starting phases or starting envelopes in other iterative algorithms.     

Recognition of external object features in gas media using ultrasound transmission tomography

The paper presents and analyzes a new way of recognizing external object features (shape, size, location) in gas media using ultrasound transmission tomography (UTT) with parallel-ray-projection scanning geometry. The concept of UTT in a gas medium is close to classical tomography, however because of the nature of the measurement environment, visualizing the internal structure of solid objects is difficult; whereas it is possible to image their external features: their shape, size and spatial location. The paper presents the results of examining the shape, size and location of different objects in the air in the form of tomographic images, obtained in parallel-ray-projection geometry, using a specially elaborated research setup for UTT. Applying parallel-ray-projection geometry enabled us to investigate the influence of scanning resolution on image quality. In order to test the operation of the elaborated algorithm of tomographic image reconstruction on the basis of correct measurement data, special software was written for simulating the binary matrix of the measurements for a set of a dozen or so solid objects of different shapes and a few simulations were performed.     

Symmetrical group theory for mathematical complexity reduction of digital holograms

This work presents the use of mathematical group theory through an algorithm to reduce the multiplicative computational complexity in the process of creating digital holograms. An object is considered as a set of point sources using mathematical symmetry properties of both the core in the Fresnel integral and the image, where the image is modeled using group theory. This algorithm has multiplicative complexity equal to zero and an additive complexity (k ? 1) × N for the case of sparse matrices and binary images, where k is the number of pixels other than zero and N is the total points in the image.     

二元综合鉴别函数的神经网络优化

根据Ｈｏｐｆｉｅｌｄ神经网络的优化功能，对综合鉴别函数进行二元优化，使相关输出具有期的望的形状及峰值大小，从而实现旋转不变识别，并定义了一个判别依据－判别比，计算机模拟的结果表明，目标物体通过优化的二元滤波器后，不仅具有期望输出，而且判别经要比伪目标物体至少大一个量级。     

二维轴对称图象高阶胡氏不变矩快速算法的改进

提出了基于二维轴对称性目标图象矩快速算法的实用化改进方案.算法实用化改进是通过两个命题的证明实现的.一是通过轴对称目标图象质心在对称轴上的命题证明,实现了将二维轴对称图象矩快速算法用于轴对称性图象中心矩的计算;二是通过目标图象以坐标系中任意两点为圆心,旋转相同角度,结果图象具有平移性的命题证明,实现了算法用于对旋转不同角度的对称目标图象的中心矩的计算改进.在此基础上,完成了二维轴对称目标图象高阶胡氏不变矩实用化快速算法的实现.实验证明,该算法具有较好的实时性能,且具有较小的引入误差.     

观测表面反射像检测精密薄板玻璃翘曲度的理论分析

分析了一种高效简便测试精密薄板玻璃翘曲度的方法。这种方法是通过观测精密薄板玻璃和基准平面反射同一参考物的像,检测两个像分离的程度来判定精密薄板玻璃的翘曲度。通过对精密薄板玻璃表面变形形态进行抽象、模拟和近似处理,从理论上推导出精密薄板玻璃翘曲度 Ｗ ≤０ ．００３ ,样品尺寸在２００ｍ ｍ ～５００ｍ ｍ 的条件下,参考物直径与测量装置结构尺寸和翘曲度之间的关系式。     

一维和二维傅里叶谱相位测量

我们利用正交偏振方法将傅里叶谱的实部和虚部分开,从而测定了一维和二维傅里叶谱的相位。文中报道了位移狭缝和位移方孔傅里叶谱相位的测量结果,它们与用位移量计算出的相位值符合很好,因此证实了该方法的可靠性。在此基础上我们还考察了其它二维二进制图形傅里叶谱的实部和虚部。     

二元位相校正技术在相控列阵光学系统中的应用

提出一种使用二元光学器件实现位相校正的新方法。在子孔径拼接的相控列阵光学系统中，采用二元光学器件二元位相校正板对子孔径拼接后产生的残留波像差进行校正，既达到位相校正技术要求，又大大简化系统结构并减小了系统的尺寸和重量。所制作的二元器件具有８个台阶，套刻精度达到２μｍ，并使残留波像差降为原来的一半。     

基于重投影的多项式拟合校正射束硬化

在X射线工业CT(ICT)中,射束硬化会导致重建的图像出现伪影,甚至产生变形。为了消除这种影响,提出了一种基于重投影的多项式拟合校正射束硬化的方法。该方法对原始CT图像进行阈值分割二值化,将物体目标区域的像素值设为1;重投影此二值图像以获取X射线贯穿物体的长度集合;利用多项式拟合此长度集合与多色投影间的关系来建立射束硬化校正模型,用该模型对多色投影进行校正。与传统的多项式拟合校正方法相比,该方法不需要楔状模体(用于测量不同厚度下的衰减值,以此来建立射束硬化校正模型)。研究表明,该方法能有效地抑制射束硬化的影响。     

光学图像与雷达图像的数据融合研究

利用可提取更多图像信息和细节的像素级数据融合方法实现光学图像和雷达图像的融合。试验表明，基于像素级的数据融合方法有效可行，生成的图像具有更好的图像质量和最小的均方误差。     

Space-time generated from a set of binary units

This paper shows that the properties of space-time that constitutes the background of the theory of special relativity, namely its dimensionality, the correct partition of dimensions between one time-type and three space-type dimensions and the Minkowski metrics, may emerge from a set of completely interacting binary units structured by a noise defined in a Landau-type free energy of Higgs fields and by gauge symmetries, in particular those related to the permutation group of four objects.Received: 28 October 2003, Revised: 23 February 2004, Published online: 3 June 2004     

A circle similarity algorithm for an automatic circular decomposition of blood cell images

This paper presents an iterative algorithm for circular decomposition which investigates the separation of overlapped circular particles of a binary image, in order to locate their center coordinates and to estimate their radii. Since this algorithm is based on the measure of a circle similarity of an object in an image to execute a search for concavities, object segmentation and circle recognition, its implementation is simpler than the algorithm based on polygonal approximation. In this work we compare the accuracy and robustness of the proposed circle similarity algorithm with a polygonal approximation based algorithm using synthetic images and real blood cell images. Both the algorithms are able to decompose connected blood cells. However, the input parameters of the polygonal approximation method shows high sensitivity to the shape or agglomeration of an object, while the proposed algorithm demonstrates more stable performance.     

Computerised Perimeter Mapping and the Measurement of Fractal Dimensions

A method is described for mapping the perimeter of shapes as a sequence of connected X & Y coordinates. It operates by tracking, in tandem, along a dilated outline of the shape and the true outline, maintaining contact between both tracks. This combination permits the complete mapping of binary shapes regardless of their complexity. The resulting sequence of X & Y coordinates form an 8-connected map of the outline, which can then be used to obtain fractal dimensions using structured walks. The method requires a digitised image that has been converted into a binary form and the ability to read the values of individual pixels from the digitised binary image. In addition a number of approaches for increasing the efficiency of the twin tracking algorithm are outlined. Obtaining fractal dimensions from a structured walk based on a fully mapped perimeter increases the accuracy of the measured fractal dimensions, extends the range of step sizes over which measurements can be made and permits a highly detailed examination of the perimeter.     

Interaction of Four Rarefaction Waves in the Bi-Symmetric Class of the Two-Dimensional Euler Equations

The global existence and structures of solutions to multi-dimensional unsteady compressible Euler equations are interesting and important open problems. In this paper, we construct global classical solutions to the interaction of four orthogonal planar rarefaction waves with two axes of symmetry for the Euler equations in two space dimensions, in the case where the initial rarefaction waves are large. The bi-symmetric initial data is a basic type of four-wave two-dimensional Riemann problems. The solutions in this case are continuous, bounded and self-similar, and we characterize how large the rarefaction waves must be. We use the methods of hodograph transformation, characteristic decomposition, and phase space analysis. We resolve binary interactions of simple waves in the process.     

Polymeric quasicrystal: mesoscopic quasicrystalline tiling in ABC star polymers

A mesoscopic tiling pattern with 12-fold symmetry has been observed in a three-component polymer system composed of polyisoprene, polystyrene, and poly(2-vinylpyridine) which forms a star-shaped terpolymer, and a polystyrene homopolymer blend. Transmission electron microscopy images reveal a nonperiodic tiling pattern covered with equilateral triangles and squares, their triangle/square number ratio of 2.3 (approximately equal to 4/sqrt[3]), and a microbeam x-ray diffraction pattern shows dodecagonal symmetry. The same kind of quasicrystalline structures have been found for metal alloys (approximately 0.5 nm), chalcogenides (approximately 2 nm), and liquid crystals (approximately 10 nm). The present result (approximately 50 nm) confirms the universal nature of dodecagonal quasicrystals over several hierarchical length scales.     

The three-dimensional equilibrium crystal shape of Pb: Recent results of theory and experiment

The three-dimensional equilibrium crystal shape (ECS) is constructed from a set of 35 orientation-dependent surface energies of fcc Pb which are calculated by density functional theory in the local-density approximation and distributed over the [110] and [001] zones of the stereographic triangle. Surface relaxation has a pronounced influence on the equilibrium shape. The (111), (100), (110), (211), (221), (411), (665), (15,1,1), (410) and (320) facets are present after relaxation of all considered surfaces, while only the low-index facets (111), (100) and (110) exist for the unrelaxed ECS. The result for the relaxed Pb crystal state is in support of the experimental ECS of Pb at 320–350 K. On the other hand, approximating the surface energies of vicinal surfaces by assuming a linear relationship between the Pb(111) first-principles surface energy and the number of broken bonds of surface atoms leads to a trivial ECS that shows only (111) and (100) facets, with a sixfold symmetric (111) facet instead of the correct threefold symmetry. It is concluded that the broken bond rule in this simple linear form is not a suitable approximation for obtaining the proper three-dimensional ECS and correct step formation energies. PACS 05.70.Np; 61.50.Jr; 68.35.Md; 71.15.Mb     

数字全息重建图像的焦深研究

将来自物体的散射光视为物体表面相位随机取值的大量点源发出光波的叠加, 对数字全息重建像及离焦像的衍射场进行研究. 基于重建像以像素为单位显示的特点, 对焦深作出新的定义, 然后, 根据重建像的像素物理尺寸与计算方法相关的特点, 推导出不同重建算法重建图像的焦深表达式, 最后给出相关的实验证明.     

最小二乘支持向量域的混沌时间序列预测

从支持向量域SVD(Support Vector Domain)出发，根据Takens延时相空间重构思想，利用支持向量机非线性映射，建立了混沌时间序列和混沌非线性相轨迹运动的SVD预测模型.采用数据集作为支持对象元素，机器自学习缩小模型泛化误差的上界，利用最小二乘支持向量域(SVD)，预测了Henon/Lorenz/Rossler三种混沌时间序列.预测结果表明，三种预测模型将集合映射到一个更高维特征空间，通过嵌入维数，实现了序列预测，误差随嵌入维数变化趋于恒定，与支持向量机(SVM)相比，SVD所需支持向量少，收敛速度快，鲁棒性强，核函数选择容易灵活，且存在自适应方法.网格点数提高了10—20倍，序列预测在小样本、非线性、未知概率密度条件下，预测和实际值取得了一致. 关键词： 支持向量域 混沌 最小二乘 时间序列预测     

正交光栅干涉仪对二维分立点物体成像

本文将正交光栅干涉仪的条纹箱分离,获得两个方向上的条纹箱.对于由N个分立点组成的物体,从两个条纹箱可以得到由N~2个点组成的像.其中N个点是物的格实像点,N(N—1)个是交叉项点.将光栅干涉仪绕其对称轴转过一角度,得到第二个像.与第一个像相比,N(N—1)个交叉项点的空间位置发生了变化,而N个真实像点未变.因此,将这两个像相乘,即能消除交叉项点而获得真实像点.利用这一方法,给出了实验结果.     

Topological extensions of Noether charge algebras carried by Dp-branes

We derive an extension of the supersymmetry algebra carried by D-branes in a massless type IIA superspace vacuum. We find that the extended algebra contains not only topological charges that probe the presence of compact space-time dimensions but also pieces that measure non-trivial configurations of the gauge field on the world-volume of the brane. Furthermore there are terms that measure the coupling of the non-triviality of the world-volume regarded as a U(1) bundle of the gauge field to possible compact space-time dimensions. In particular, the extended algebra carried by the D2-brane can contain the charge of a Dirac monopole of the gauge field. In the course of this work we derive a set of generalized Gamma-matrix identities that include the ones presently known for the IIA case. In the first part of the paper we give an introduction to the basic notions of Noether current algebras and charge algebras; furthermore we find a theorem that describes in a general context how the presence of a gauge field on the world-volume of an embedded object transforming under the symmetry group on the target space alters the algebra of the Noether charges, which otherwise would be the same as the algebra of the symmetry group. This is a phenomenon recently found by Sorokin and Townsend in the case of the N15-brane, but here we show that it holds quite generally, and in particular also in the case of D-branes.