利用格子气自动机模拟扩散现象的教学研究

利用格子气自动机模拟扩散现象,呈现了扩散的细节。文中对模拟过程的讨论和分析,可为格子气自动机方法应用于大学物理虚拟实验提供参考,也为将其他复杂系统模拟方法应用于物理教学提供借鉴。     

相位图去包裹方法及其进展

近年来付立叶变换法和相移法在辅助光学测量中得到了广泛的应用,但处理后的相位图一般包裹在[-π,π)间,要获得正确的物理变化信息,需要对原始相位图进行去包裹运算。相位去包裹算法主要有传统算法、分割线算法、最小二乘算法、细胞自动机算法、付立叶变换算法、质量导向图算法等。本文较详细地阐述了几种相位去包裹算法的数学模型和基本原理及其最新进展,分析了各自的优缺点及其适用范围。     

用细胞自动机方法模拟计算二维流体的平衡与非平衡相关函数

本文采用一个含有温度的简化点阵气模型,通过细胞自动机方法,模拟计算了服从于外部温度梯度的二维流体中的平衡与非平衡空间相关函数。数值结果表明,用本文方法所计算的结果与由涨落流体动力理论的预言在是性上是完全符合的。     

量子细胞神经网络的超混沌特性研究

研究了由量子点细胞自动机构成的量子细胞神经网络的非线性动力学特性.以量子点细胞的极化率和量子相位作为状态变量，对3个细胞耦合的量子细胞神经网络进行了理论分析和计 算机仿真研究.结果表明，该网络系统呈现复杂的混沌动力学行为，混沌振荡产生非常容易. 由数值计算得到的两个最大正Lyapunov指数证实了该系统具有超混沌特性. 关键词： 量子点细胞自动机 极化率 量子细胞神经网络 超混沌     

一维几率性细胞自动机演化的临界相变现象分析

本文用实位置空间重整化群方法对一类特殊的一维几率性细胞自动机演化的动力学方程进行了处理,得到该细胞自动机的演化存在相变,其临界点几率参数值为P₀=0,P₁=P₂=0.5,临界动力学指数z=2,并获得了大量的计算机实验资料。     

用细胞演化算法研究原子结构问题

精确地计算磁场中二电子体系的基态能量是非常复杂和困难的,作者已用演化算法成功地处理了这类问题。并进一步针对传统演化算法中演化操作的对象是点集的不足,提出了一种改进的演化算法——细胞演化算法。此算法的主要思想是对集合进行操作,再采用嵌套式二次搜索方法以达到寻找最优解的目的。结果表明它不仅能处理复杂原子结构问题,而且较之传统的演化算法有速度快、精确度高等特点。     

武器自动机运动规律测试系统光斑定位算法的研究

针对重心法、高斯拟合法等传统的光斑中心定位算法存在抗干扰能力差、定位精度低等问题,提出了一种以圆拟合算法为基础进行改进计算光斑中心的方法。采用56式冲锋枪进行实弹单发实验,对测试系统获得的数据分别用改进圆拟合、高斯拟合及重心法进行处理。将处理结果与OFV5000激光速度计测试结果相比较,改进圆拟合算法的相对误差仅为0.92%。结果表明:该算法提高了抗干扰能力,实现了光斑中心的快速、准确计算,并且获得了武器自动机运动规律。     

基于元胞自动机法的高温金属腐蚀行为模拟

本文基于元胞自动机方法对镍-铬合金在高温的含硫腐蚀性气氛中的氧化腐蚀行为进行模拟。模型中的重要变量包括反应概率、反应时间以及腐蚀层厚度。模拟结果表明,元胞自动机方法可以模拟出金属在氧化-硫化复杂化学反应体系,腐蚀层厚度符合Wagner抛物线理论。另外,研究了不同参数对镍-铬二元合金腐蚀的影响,结果表明,相同反应概率下,Cr浓度升高,反应物厚度减小,体现了铬的腐蚀防护性。     

一种基于误差快速扩散元胞自动机的加密技术

构造了一个具有较大密钥空间的新型一维元胞自动机. 在该元胞自动机中,密钥为采用移位映射的伪随机序列及受控扰动项,避免了数据膨胀,元胞自动机具有随机性触发规则. 该元胞自动机一次处理信息量大,避免了复杂的计算过程. 所生成的流密码在理论上被证明了具有理想的随机性与雪崩效应,误差扩散速度快. 实证分析研究表明,流密码不仅在全局上、而且在局部上都具有良好的随机性能,通过测试长度为24000的流密码在400次迭代产生的数据表明,经χ²检验,在显著性水平为5%时,频数检验通过率超 关键词： 保密通信 元胞自动机 伪随机序列     

格点自动机与探索复杂性

从1983年美国年轻物理学家斯·沃尔夫拉曼对格点自动机(亦称细胞自动机)的大力宣传,到1986年格点自动机流体动力学模型(FHP模型)的提出,以及1987年《Complex Systems》杂志的创刊,这一领域的研究可谓高潮迭起。而美国洛斯·阿拉莫斯国家实验室非线性中心近几年的几次年会更起了推波助澜的作用。目     

双模晶体相场研究形变诱导的多级微结构演化

本文采用双模晶体相场模型,计算了双模二维相图;模拟了形变诱导六角相向正方相转变过程的多级微结构演化,详细分析了位相差、形变方向对位错、晶界、晶体结构、新相形貌的影响规律.模拟结果表明:形变方向影响正方相晶核的形核位置和生长方向,拉伸时正方相优先在变形带上形核,垂直于形变方向长大,而压缩时正方相直接在位错和晶界的能量较高处形核,平行于形变方向长大;位相差对形变诱发晶界甄没过程有显著影响,体现在能量峰上为,小位相差晶界位错的攀滑移和甄没形成一个能量峰,大位相差晶界位错攀滑移和甄没因分阶段完成而不出现明显的能量峰;形变诱导相变过程中各种因素相互作用复杂,是相变与动态再结晶的复合转变.     

Reconstructing a complex field from a series of its near-field diffraction patterns

We propose a method for reconstructing a complex field from a series of its near-field diffraction patterns.This method is based on the paraxial Fresnel diffraction equation without making further approximations.Numerical simulations are presented showing that a complex field can even be reconstructed with moderate qualities from its two near-field diffraction patterns and almost exact reconstructions can be obtained when three or more diffraction patterns are used.We also show by numerical simulation that the correct diffraction distances can be recovered in case only coarsely measured values are available.This method may be applied to phase imaging of weak-absorption objects.     

Realization of Absolute‐Phase Unwrapping and Speckle Suppression in Laser Digital Holography

In this paper, an absolute‐phase unwrapping and speckle suppression approach to reconstruct a three‐dimensional (3‐D) image of an object with laser digital holography is described. This method offers three advantages to enhance the performance of the phase reconstruction technique. First, both speckle suppression and phase unwrapping are processed in the complex amplitude domain rather than in the single phase or amplitude domain. With this approach, the phase details of the object are better preserved upon phase reconstruction. Second, the proposed algorithm requires no threshold determination and thus achieves self‐adaptive speckle suppression and robust phase unwrapping, in contrast to other methods. Finally, an improved dual‐domain image denoising method is applied to further remove speckle‐remnant‐induced phase distortion. Ideal 3‐D phase reconstruction results are obtained both theoretically and experimentally for the first time.     

Phase coding in iterative synthesis of computer-generated holograms

A new method is investigated for phase-only hologram synthesis. The method combines iterative calculation of the hologram phase function with the coding of the amplitude-phase characteristics of the complex transmission function into phase characteristics. The results of computational experiments are presented. The phase masks and reconstructed object images are also presented.     

相位调制数字散斑干涉术

提出一种可绕Ｚ轴转动的粗糙平板（参考物体）实现相位调制，该方法在不改变电子散斑干涉术（ＥＳＰＩ）或数字散干涉术（ＤＳＰＩ）系统装置的情况下，可用于微小离而位移场（例如最大离面位移为λ）的测量，以及复杂形变的离面位移场的自动测量。     

Crystal structure and thermochemical properties of bis（1-octylammonium） tetrachlorochromate phase change materials

A new crystalline complex(C8 H17 NH3) 2 CdCl 4(s)(abbreviated as C8Cd(s)) is synthesized by liquid phase reaction.The crystal structure and composition of the complex are determined by single crystal X-ray diffraction,chemical analysis,and elementary analysis.It is triclinic,the space group is P-1 and Z = 2.The lattice potential energy of the title complex is calculated to be U POT(C 8 Cd(s))=978.83 kJ·mol-1 from crystallographic data.Low-temperature heat capacities of the complex are measured by using a precision automatic adiabatic calorimeter over a temperature range from 78 K to 384 K.The temperature,molar enthalpy,and entropy of the phase transition for the complex are determined to be 307.3±0.15 K,10.15±0.23 kJ·mol-1,and 33.05±0.78 J·K-1 ·mol-1 respectively for the endothermic peak.Two polynomial equations of the heat capacities each as a function of temperature are fitted by using the leastsquare method.Smoothed heat capacity and thermodynamic functions of the complex are calculated based on the fitted polynomials.     

Numerical approach for reflections and transmittance of finite plane-parallel absorbing and scattering medium subjected to normal and diffuse incidence

The discrete ordinate method (DOM) is used to analyze the radiative energy transfer in one-dimensional absorbing, scattering and non-emitting planar slab subjected to normal and diffuse incidence. To improve the ability of DOM to treat complex scattering phase function, a revision of DOM is presented. The reflectance and transmittance of a semitransparent planar slab is calculated by the DOM. The results are compared with the exact values and the solution arrived at other approximate method. It is shown that the DOM has a good accuracy in solving the reflectance and transmittance of a semitransparent planar slab, and can easily treat the complex scattering phase function.     

Photoacoustic Spectroscopy Studies on DL-β-Phenylalanine and Pd(Phe)2·H2O Complex

The complex crystal of Pd(Phe)2·H20 was synthesized and its PA spectra (with DL-β-Phenylalanine) were also determined in the range of 280–780nm at room temperature and explained. A method used to resolve the PA amplitude spectrum was suggested. With the phase spectrum of complex, the PA absorption peaks were resolved by this method, and the nonradiative relaxation time of all absorption bands were calculated.     

非线性小数重合法及其在轮廓测量中的应用

叠相还原的困难是光栅投影式轮廓测量技术中影响可靠性和阻碍自动化测量的最大问题。本文提出了一种新型的时域叠相还原算法－－非线性小数重合法,这种新方法可以将可靠测量扩大数部,而不失测量精度。文中详细论述了非线性小数重合法的原理,并给出了轮廓的可靠测量的实验结果。     

基于单幅图像的工业内窥镜相位法三维测量研究

用于工业内窥镜的相位法三维测量受探头尺寸限制,要求装置简单。求取相位的常用方法有相移法和傅里叶变换法。将傅里叶变换法用于内窥镜的相位法三维测量克服了相移法的移相装置复杂,需要多幅图像,计算量大的缺点。该方法只需一幅图像就能完成测量,测量精度比相移法略低。