基于数字散斑相关方法的微位移测量

介绍了数字散斑相关方法的基本原理,利用模拟散斑图分析了3种常用亚像素算法的性能.根据数字散斑相关方法测量微位移的特点,采用爬山搜索法进行整像素搜索,采用计算量小、计算精度高的基于梯度的算法进行亚像素搜索.利用千分表和数字散斑相关方法对有机玻璃梁试件三点弯曲中心挠度进行了测量,并与有限元计算结果进行了比较.结果表明,数字散斑相关方法测量微位移的实验系统是可靠的,在此基础上测量了试件加载位置附近区域的全场位移.     

基于布谷鸟算法的数字散斑相关方法优化

将布谷鸟算法引入到数字散斑相关方法的搜索中,通过设定隔离边界对数字散斑图像分块,在每一个子块上利用布谷鸟算法进行局部搜索,在此基础上利用爬山算法进一步搜索峰值。全局搜索可以设定一个较弱的收敛条件,快速搜索到相关系数分布单峰上,充分利用了布谷鸟算法的全局搜索能力与爬山算法的快速收敛特点;最后通过模拟散斑图片进行了相关仿真,并通过实际人工散斑进行了相关实验,表明该算法能有效稳定测量刚体的位移量。     

基于数字散斑自相关技术的微位移测量

通过散斑照相实验,得到粗糙表面在激光照射下的散斑场,移动粗糙表面,记录位移前后的散斑图像,利用数字散斑相关方法分析散斑图像,即可确定粗糙表面的位移。理论分析和实验结果表明,数字散斑相关技术可以很好地实现测量带有粗糙表面物体的微小位移,精度可达微米级。     

数字散斑相关法测量连续位移的原理与实验

提出用数字散斑相关方法测量移动物体的连续位移.激光照射粗糙表面形成散斑场,用CCD记录粗糙表面移动时的序列散斑图像,利用数字散斑相关方法分析散斑图像,确定粗糙表面的位移.研究结果表明,数字散斑相关技术可以高精度地测出连续移动物体的位移.     

DSCM中摄像机光轴与物面不垂直引起的误差分析

该文研究了数字散斑相关方法(DSCM)中由于摄像机与被测物面不垂直而引起的误差。首先从成像原理上进行分析,得出当位移和偏差角度比较小时,误差分别与它们成线性关系。为验证这一结论,提出了引入摄像机成像模型的数字模拟散斑图像生成方法;采用数字散斑相关方法,对模拟散斑图像进行计算,计算的结果与理论分析的误差公式结果非常吻合。基于数字散斑相关测量灵敏度为0.01像素,要求不垂直度或被测平面的平面度应小于5,°这也是二维数字散斑可否用于曲面测量的判据。     

数字图像相关方法最优散斑尺寸

综合分析了图像灰度噪声和亚像素插值误差这两种最主要的误差源对数字图像相关方法位移测量精度的影响,并在此基础上建立了计算数字图像相关方法的总测量误差数学模型.在综合考虑这两种误差的基础上具体分析了散斑尺寸对数字图像相关方法的位移测量精度的影响,运用理论分析和数值模拟得到了不同参数下的最优散斑尺寸.研究结果表明,对于一定的测量参数而言,存在一个散斑尺寸的最优区间,在这个区间内的散斑越多,数字图像相关方法的位移测量精度越高.     

显微图像相关处理原理及其应用

基于图像识别原理,对数字散斑相关方法做了新的理论探讨,通过分析散斑位移及其导数对变形前后显微图像相关性的影响,对相关算法进行简化和改进,提出了相关识别法,大大减少了相关迭代的计算时间。图像预处理有助于提高图像的相关性。典型的实验证明了该方法的可行性、准确性。     

模拟散斑尺寸对数字图像相关算法影响分析

数字散斑测试精度的影响因素相对较多、精准控制难度较大,定量分析程度不足。为了提高数字散斑测试精度,文章通过模拟散斑的方法分析观测散斑尺寸大小对计算结果的影响。结果表明：随着散斑尺寸的增加,位移计算误差呈现先降后升的趋势,即散斑尺寸过大或者过小都不利于数字图像相关的位移计算,最优散斑尺寸为5～7像素。研究结果为数字图像相关计算的观测对象设计提供了数据基准,为实际现场监测的观测目标变形信息的精度提高提供了数据基础。     

极值搜索法在数字相关性计算中的应用

通过对数字散斑相关性计算公式的分析,提出了计算相关性的极值搜索法,将平面上散斑的连续搜索变为离散搜索,将二维搜索变为一维搜索。同时,通过样条插值法完成非整数像素点的搜索。实验结果表明,该方法能明显提高散斑搜索的速度和灵敏度,并能达到满意的计算精度。     

基于光照不变特征的数字散斑相关方法

边坡问题是中外工程建设中的主要工程地质问题之一,准确、可靠的边坡变形监测方法对预防滑坡灾害起着至关重要的作用.将数字散斑相关方法应用在边坡变形监测中,可以快速得到准确的边坡位移场信息,具有操作简单、非接触式等优点.但是在野外测量环境下,光照变化对图像的灰度唯一性产生了较大影响,从而导致测量精度的下降.在数字散斑相关方法求解边坡变形场的基础上,使用局部敏感直方图替换原始图像对应位置的灰度值,作为图像的光照不变特征,克服了光照变化对图像灰度信息的影响,并通过数值模拟实验对算法精度进行验证.实验结果表明,该方法大幅提高了边坡变形计算精度,为研究边坡破坏机理和发展过程,提供了一种经济有效的监测方法.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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