CCD高分辨成像的梯度解析法

基于序列图像重建的高分辨成像技术需要获取互有位移的序列图像,并需利用图像重建算法进行高分辨率图像重建。为此,设计了一种利用压电陶瓷体控制CCD位移来获取互有微小位移的序列图像的装置,在此基础上提出了一种基于梯度理论从序列图像重建高分辨率图像的算法——梯度解析法。该解析法根据图像灰度场梯度理论,同时考虑了图像的更高频成分,提高了重建图像分辨率。仿真实验显示,该算法与已有算法相比,重建图像的失真度降低40％以上。     

基于路径匹配技术的高精度微位移检测系统

文中研究了用图像技术来检测微位移的问题 ,提出一种路径匹配微位移检测算法。该算法能自动搜索移动前后图像中匹配边缘 ,并避免了常用图像匹配算法复杂度太大的问题。文中还对算法进行了可信性分析并给出了实验结果。理论分析和实验结果表明 ,路径相关微位移检测算法运算量小且获得了亚像素的准确度     

基于SSDA的模板匹配法在指纹识别中的应用

基于细节提取的指纹识别算法需要进行复杂的预处理，直接FFT求相关系数法计算量很大．提出了一种结合SSDA和模板匹配法的指纹识别算法．试图简化处理过程，提高处理速度．其基本思想是采用序贯相似性检测算法（SSDA）快速得到候选匹配子图，再通过求子图与模板的相关系数来判别两幅指纹图像是否匹配．采用指纹库中的指纹图像进行了大量实验．实验表明，该算法简化了处理过程，相对于直接FFT求相关系数法，运算速度提高了近10倍．     

互相关 DPIV 技术及其在氧化沟模型中的应用

重点研究二维DPIV技术的速度信息提取方法并进行算法实现。该技术基于灰度图像互相关法,在相邻时刻的序列图像中,灰度分布最相似的子窗口即是最佳匹配,粒子在像平面上的运动位移由两个子窗口中心距离确定。通过对互相关测度的优选既能兼顾粒子匹配成功率也能降低匹配算法的时间开销,通过优化算法的搜索空间极大地减少了互相关运算量。给出了标准图像仿真结果及其在氧化沟模型流速测试中的成功应用。实验结果表明,该算法适合于氧化沟模型流场及类似场合的测速。     

基于改进Census变换的鲁棒立体匹配算法

针对局部立体匹配算法对噪声与光照变化敏感及在弱纹理区域匹配效果不佳的情况，提出一种基于改进Census变换与自适应参数引导滤波的立体匹配算法。该算法融合HSV通道值计算代价，对噪声与光照变化有较好的鲁棒性；在支持窗口内分别使用欧式距离加权与颜色加权获得Census变换参考值；集成AD与Census代价提高了单像素匹配代价的稳定性，降低了原Census变换对中心像素的依赖程度。在代价聚合过程中使用峰度系数对正则化参数进行自适应处理，通过视差计算获得视差图。在VS2017平台上对Middlebury数据库提供的图像对进行匹配实验，该算法在标准图像、加噪声图像及光照变化图像的各区域平均误匹配率分别是7.80%、10.72%和9.89%。结果表明：该算法可以降低误匹配率，同时能更好地适应噪声与光照变化。     

一种新的DPIV处理方法及其系统实现

本文首先简述数字粒子图像测流体速度场DPIV（Digital Particle Image Velocinmetry)的基本原理，提出一种新的DPIV快速算法－改进序贯似性检测算法，该算法直接在空域里处理DPIV图像，利用粒子图像特征，最大限度地去除冗余的处理，计算量比空域互相关算法提高两个数量级。就解决亚像素位移精度的问题提出了相位拟合法。最后，详细地分析了DPIV系统的一些关键性设计，并给出了实验结果。     

一种基于灰度投影与块匹配的视频序列快速稳像算法

针对视频图像序列的不稳定性,结合灰度投影算法与块匹配法各自的特点,提出了一种可以快速消除图像序列间平移和旋转抖动的新型电子稳像算法.该算法首先采用灰度投影法估计与补偿图像序列间的平移运动,然后用拉普拉斯算子在图像边缘处选取灰度信息比较丰富的小块模板,利用块匹配法计算模板的平移运动,再结合模板在图像上的位置估计图像的旋转...     

蜂窝纸芯成形质量在线检测系统的开发

基于MATLAB 开发软件,对蜂窝纸板生产过程中蜂窝纸芯的成形质量进行了在线自动检测。将生产线上获得的蜂窝纸芯实际图像进行处理后,与标准模板图像进行比对运算,得出蜂窝纸芯的实际生产质量情况。比对算法的关键有2 个:在图像中寻找匹配目标;将实际图像与模板图像的匹配部分进行相似度计算。采用相关模板匹配的方法进行目标匹配,采用逐个像素点比较的方法进行相似度的比对计算,通过该算法可以高效快速地将实际图像与模板图像中提取的匹配部分进行运算,得到其相似度,获得产品的生产质量。     

利用无线局域网遥测的3-D表面轮廓重构

提出一种基于IEEE820.11无线局域网(WLAN)遥测捕获图像的三维恢复算法,通过无线网络中的现场计算机获取远端物体双目图像,采用立体视觉法对双目图像的精确匹配,得到三维场景的精确重构恢复。实验结果表明,该算法能有效地实现双目图像匹配和恢复远端物体的三维表面信息。     

基于塔型结构的快速相关跟踪算法

提出一种能自适应的确定相关匹配搜索范围的快速相关跟踪算法。该算法结合两点线性预测器和图像塔型结构的多分辨力分析方法,综合图像在不同尺度下的位置信息,自适应地计算出相关匹配的搜索范围,减小了相关运算的计算量,同时确定了有效的帧间相关置信度估计和模板更新策略。实验证明此算法计算速度快,能持久稳定地跟踪运动目标。     

Parametric semi-blind deconvolution algorithm with Huber–Markov regularization for passive millimeter-wave images

Passive millimeter-wave (PMMW) images often suffer common problems of noise and blurring. A new method is proposed to estimate the instrument response function (IRF) and desired image simultaneously. The proposed variational model integrates the adaptive weight data term, image smooth term, and IRF smooth term. The major novelty of this work is that Huber–Markov regularization is adopted for PMMW image restoration, which can preserve structural details as well as suppress noise effectively. The IRF is parametrically formulated as a Gaussian-shaped function based on experimental measurements through the utilized PMMW imaging system. The alternation minimization iterative method is applied to achieve the IRF width and desired image. Comparative experimental results with some real PMMW images reveal that the proposed approach can effectively suppress noise, reduce ringing artifacts, and improve the spatial resolution.     

Single-shot full resolution region-of-interest (ROI) reconstruction in image plane digital holographic microscopy

We describe a numerical processing technique that allows single-shot region-of-interest (ROI) reconstruction in image plane digital holographic microscopy with full pixel resolution. The ROI reconstruction is modelled as an optimization problem where the cost function to be minimized consists of an L2-norm squared data fitting term and a modified Huber penalty term that are minimized alternately in an adaptive fashion. The technique can provide full pixel resolution complex-valued images of the selected ROI which is not possible to achieve with the commonly used Fourier transform method. The technique can facilitate holographic reconstruction of individual cells of interest from a large field-of-view digital holographic microscopy data. The complementary phase information in addition to the usual absorption information already available in the form of bright field microscopy can make the methodology attractive to the biomedical user community.     

光谱Neugebauer模型的抗差最小二乘优化

Yule-Nielsen修正光谱Neugebauer模型是一种用来预测彩色网目调印刷品颜色的重要光谱预测模型。为了提高Neugebauer模型预测精度,在分析光谱Neugebauer模型和抗差估计理论的基础上,提出了将抗差最小二乘法用于计算模型参数网点面积率和基色光谱反射率。常用的抗差估计方案有:Huber估计和IGG估计。实验表明,当存在粗差的情况下,与传统的最小二乘法相比,抗差最小二乘法的光谱Neugebauer模型的预测精度更高且更为稳定。     

脉冲噪声的最小均值M－估计有源控制算法

经典的滤波―X最小均方算法(Fx LMS)已经被广泛应用于有源噪声控制(ANC)领域。 但是当存在脉冲噪声时, 它的性能就会严重退化。基于鲁棒统计的概念介绍了一种新型自适应算法,采用的目标函数为M－估计函数, 而不是传统的最小均方误差。该算法分别采用了Huber 函数、Hampel 三段下降M估计函数等四种不同的M－估计函数作为目标函数,仿真结果表明所采用的算法能有效地消除脉冲噪声,并且与日本学者Akhtar 改进的加窗算法相比表现了更好的收敛性。     

Robust inversion for material parameters identification from correlated outlying observations

In this paper, a novel robust inversion method for correlated observations (RIMCO) is proposed to determine the material parameters from correlated observations under the effect of outliers and leverage points. This method is based on a full equivalent weight matrix established from the original measurement weight matrix and an adapted full weight matrix with hard rejection to outliers. This equivalent weight matrix plays key role to refine the stochastic model, while keeping the original correlation of measurements unchanged on the one hand, and ensuring simultaneously high robustness and statistical efficiency of the proposed method, on the other hand. The performance of the proposed method is demonstrated by considering a rockfill dam as an example, where the material parameters are identified from geotechnical and geodetic measurements after achievement of the construction, and during the first filling up of reservoir. Results of comparison of RIMCO with least squares and M Huber methods concerning their robustness and efficiency are presented for various configuration options.     

Numerical limit analysis of perforated plates

Full limit analysis is preseted of a thin plate under plane stress, perforated with circular holes arranged in a regular penetration pattern. The material is assumed to be elastic–perfectly plastic and to obey the Huber–Mises yield condition together with its associated flow law. The finite element tangential stiffness method is employed. Triangular constant-strain elements are used, the load being generated by means of constant edge displacements at the periphery of a suitably selected subregion. Load-displacement diagrams are obtained for various edge displacement programs and then an interaction curve is constructed for the perforated plate considered. Each computational step is associated with a certain plastic zone which develops until the limit state configuration is reached. The plate is provided with equilateral triangular configuration of holes with arbitrary cutout coefficients. The interaction curves are plotted against the Huber–Mises yield condition for the plate without openings.     

数值计算中的一种无网格方法研究

主要工作是推导了一种基于新的形函数形式的无网格方法。由于目前的无网格方法中,紧支域的大小和形状不同直接影响整体场函数的分布,有时会造成计算结果的严重失真。为了弱化紧支域尺寸的选取对计算结果的影响,以节点约束的形式构造一种形函数对位移场进行近似。一维位移场的计算实例表明方法能有效的弱化覆盖尺寸对计算结果的影响。一个简单的三维数值算例也表明利用该形函数构造的应变场进行无网格方法计算是可行的。方法的缺点是弱化核函数覆盖尺寸的影响是以增大计算量为代价的,需进一步改进。     

Influence of the patch field on work function study using the onset method

Work function study based on the onset method (WFS) is a surface technique used for investigation of the adsorption and deposition processes. When applied using scanning electron beam, it can be used for surface mapping of the work function with the lateral resolution presumably comparable to that of primary beam spot size. Such experimental arrangement is known as Work Function Microscopy (WFM). In the case of a non-uniform surface distribution of the work function, a contact potential is established between areas having different work function. The corresponding electrical field, known as patch field, influences work function study using the retarding field potential. Although this influence should be also present when using the onset method, this problem has not been tackled so far in these measurements. In this work we calculate the potential distribution above a single low work function patch on a high work function substrate. The potential distribution is evaluated in the presence of the external field, which is a common situation in WFS and WFM measurements. We show that WFS and WFM results may be strongly influenced by the patch field. Their interpretation depends on the external field and the size of areas (patches) having uniform local work function.     

海上远景小目标检测方法的研究

海水本身运动的复杂性以及海水与其它环境因素所产生的干扰物理场,往往使得海上小目标的探测尤为困难.因此,以可见光图像序列中海面小目标检测为研究对象,提出了核函数-马尔科夫随机场(Markov Random Fields,MRF)前景分割模型.该模型利用所提出的邻域相关核函数背景模型对图像序列的求解结果作为MRF的观测值,...     

Higher moments of weighted integrals of non-Gaussian fields

In general, the exact probability distribution of a definite integral of a given non-Gaussian random field is not known. Some information about this unknown distribution can be obtained from the 3rd and 4th moment of the integral. Approximations to these moments can be calculated by discretizing the integral and replacing the integrand by third-degree polynomials of correlated Gaussian variables which reproduce the first four moments and the correlation function of the field correctly. The method described (see Ditlevsen O, Mohr G, Hoffmeyer P. Integration of non-Gaussian fields. Probabilistic engineering mechanics, 1996) based on these ideas is discussed and further developed and used in a computer program which produces fairly accurate approximations to the mentioned moments with no restrictions put on the weight function applied to the field and the correlation function of the field. A pathological example demonstrating the limitations of the method is given.