基于灰度共生矩阵的表面粗糙度研究

介绍了激光散斑的形成及其统计性质,拍摄大量不同加工工艺、不同表面粗糙度标准样块的散斑图像,基于激光散斑图像的灰度共生矩阵及惯性矩、角二阶矩、熵、相关性4个参量,对图像进行了纹理分析.分别绘制了不同加工工艺、不同表面粗糙度标准样块的4个参量与表面粗糙度关系的特性曲线.最后将实验结果和未知表面粗糙度工件的实验数据进行比对,准确估算出了工件的表面粗糙度.     

基于自相关函数的非平面表面粗糙度的图像纹理研究

采用自相关函数对不同加工工艺形成的非平面工件表面粗糙度进行了研究。讨论了自相关函数及其扩展度参数与图像纹理特性的关系,构建了实验装置,利用图像处理软件对实验所得的激光散斑图像进行了处理,得到了自相关函数及其扩展测度参数随表面粗糙度的变化曲线。为研究非平面工件的粗糙度,提供了一种新的方法。     

基于机器视觉的表面粗糙度测量与三维评定

表面粗糙度的测量与评定一直是机械行业的重要课题。提出了一种基于机器视觉检测工件表面粗糙度的方法。首先利用显微镜获取端铣、刨、车不同等级下工件表面的序列图像,采用方差聚焦测度算子对序列图像中的每一个点进行高度计算;然后再利用高斯插值法计算出微观物体表面的准确高度,重构其表面微观形貌;最后计算出各个工件表面的三维粗糙度。通过对实验数据的分析和讨论,可以确定出表面均方根偏差Sq、表面偏斜度Ssk和表面峰密度Sds这三个参数,它们是常用地对工件表面粗糙度进行评价的可靠参数,可为以后三维粗糙度体系的科学建立提供依据。     

干涉显微镜测量表面粗糙度条纹的自动处理

本文介绍了用干涉显微镜对表面粗糙度检测时干涉条纹的计算机处理过程，其中采用灰度阈值分割法进行干涉图像二值化处理，采用边界描迹法萃取干涉条纹边界线，可对高度偏差≤λ／２的表面粗糙度进行测量。     

基于灰度共生矩阵的自动聚焦算法

为了快速而准确的进行聚焦,提出一种基于灰度共生矩阵的自动聚焦评价算法。算法利用灰度共生矩阵提取图像的纹理,以此矩阵的对比度作为图像的清晰度值;为了提高算法的实时性,在计算对比度时,选取合适的阈值去掉矩阵对角线附近灰度差较小的元素,减少算法的计算量。实验结果表明:算法满足无偏性和单峰性,具有较高的灵敏度和陡峭度,聚焦性能较好,对引入噪声的图像同样具有很好的聚焦性能。     

车削零件表面粗糙度图像法检测优选方法

为实现对车削零件表面粗糙度检测,提出一种基于机器视觉表面粗糙度检测图像处理的新方法。该方法先按相应算法对所采集图像剔出受光衍射影响严重区域,然后再按其灰度分布情况进行区域优化,获得的图像灰度特征参数能反映表面粗糙度量值的有效特征区域。用该方法对表面粗糙度Ra标称值为0.8 μm~12.5 μm的五种车削样件测试,处理后图像灰度的均值、方差、能量和熵等特征参数与Ra标称值单调关系显著,各特征曲线的非线性误差均在1.5%以内。对比实验显示,这种特征提取和区域优化方法可应用于表面粗糙度的区分与检测。     

刹车片表面缺陷的图像检测方法

针对汽车刹车片表面纹理情况不一、种类繁多的问题，提出一种基于机器视觉的刹车片表面缺陷图像检测方法，该方法结合了灰度共生矩阵与密度聚类。首先提取刹车片的摩擦面，然后确定灰度共生矩阵的构造因子的选取，利用线性相关性选择特征参数。将每个摩擦面切分成若干小窗口，计算各个小窗口的特征值构造特征数据集，通过自适应密度聚类算法进行聚类分析，从而进一步判断是否存在缺陷区域。通过对58块不同型号的刹车片样本进行检测结果统计分析，实验表明，该方法误检率为8%，漏检率为6%，具有较高的检测精度，因此，该方法能够较好地检测刹车片样本是否存在缺陷，具有广泛的适用性。     

纹理分析在红外目标识别中的应用

若背景有雾时，红外图像中的目标会受到影响而变得比较模糊。雾的纹理是一种比较典型的自然纹理，利用灰度共生矩阵提取纹理特征图像的方法，对雾天获取的红外图像进行分析。通过实验证明了该方法对红外图像中（背景有雾时）目标的提取和识别有积极的作用。     

微光夜视仪分辨力客观测量方法研究

利用灰度 梯度共生矩阵模型对微光夜视仪分辨力测量图像的纹理特征进行了分析 ,通过对大量图像的 5个纹理特征参数的计算 ,结果表明 ,这些参数能对微光夜视仪分辨力测量图像的纹理特征作出有效的客观评价 ,此计算结果与人眼的观察结果具有较好的一致性。     

基于中值的平方距离对称共生矩阵阈值化方法

对灰度概率分布呈现偏斜和重尾的一类图像的阈值选取问题进行了研究.鉴于应用均值方法进行分类估计出现偏差的问题,本文应用中值方法进行修改,使图像阈值的选取更加合理.基于平方距离的对称共生矩阵阈值方法,在对称共生矩阵上定义了区域中值,提出了基于中值进行分类统计的平方距离对称共生矩阵阈值法,并给出了多阈值分割计算式.与Otsu′s法、基于平方距离法的分割比较表明:本文提出的方法不仅对于分类概率呈现偏斜和重尾的情况分割效果突出,而且由于考虑了图像的空间信息,与基于中值的Otsu′s法相比,所提取的目标信息更加完整,边缘更加清晰;对于小目标类的图像,该方法也具有良好的阈值选取效果.为进一步说明该方法的正确性和有效性,基于标准分割图像进行了误分类误差计算,结果表明所提出的方法误差值能够达到最小.     

Complete wetting characteristics of micro/nano dual-scale surface by plasma etching to give nanohoneycomb structure

A variety of flat superhydrophilic surfaces have been fabricated for biological and industrial applications. We report here the preparation of a simple and inexpensive non-polar curved superhydrophilic surface. This surface has dual-scale surface roughness, on both micro- and nanoscales. Curved surfaces with a near-zero water contact angle and ‘complete wetting’ are demonstrated. By using a conventional plasma etching process, which creates microscale irregularity on an aluminum surface, followed by an anodization process which further modifies the plasma etched surface by creating nanoscale structures, we generate a surface having irregularities on two-scales. This surface displays a semi-permanent superhydrophilic property (if the surface has no damage by the exterior failure), having a near-zero contact angle with water drops. We further report a simple and inexpensive curved (i.e., non-planar) superhydrophilic structure with a near-zero contact angle. The dual-scale character of the surface increases the capillary force effect and reduces the energy barriers of the nanostructures.     

Irregularities at the {001} surface of MgO: Topography and other aspects

Non-planar sites (e.g. kinks, corners and ledges) are believed to be important in such processes as corrosion, catalysis and crystal growth, but it is difficult to obtain information about their surface relaxation or properties by experimental means. We have therefore studied them using theoretical methods, and present calculations on the topography of non-planar surface sites in the fcc materials MgO, CaO, NiO and NaCl. The models used in the calculations involved both cavities of vacancies within the planar surface and blocks of adatoms above it, and the validity of using such models is discussed. In addition, a more detailed study is undertaken for the doping of non-planar sites in MgO, and comparison is made with the bulk and at the planar {001} surface. Finally, a brief discussion of some thermal excitation energies, both in the planar surface and at selected irregularities in the non-planar surface, is given.     

Selective gold nano-patterning on flexible polymer substrate via concurrent nanoimprinting and nanotransfer printing

We report a simple technique of selective gold nano-patterning on non-planar polycarbonate substrate by combining nanoimprinting and gold nanotransfer printing techniques in a single concurrent nano-patterning process: thermal nanoimprinting directly patterns a MPTMS (3-mercaptopropyl trimethoxysilane)-coated polycarbonate sheet to form the non-planar nanostructures using a gold-film deposited mold. Simultaneously, the gold-film from the mold is selectively transfer-printed either onto the protrusion or the base of the imprinted non-planar structures. This high nano-patterning selectivity is achieved due to a combined effect of a thiol-terminated MPTMS-gold surface chemistry, more importantly, aided by a surface area dependent differential work of adhesion. We show the high delineation of the patterned gold on the non-planar polycarbonate substrate of various geometries such as pillars, dimples, and gratings, down to nano-scale resolution (130 nm) as well as over micro-scale resolution (10 μm), thus demonstrating that this can be a generic metal patterning technique. Using this technique, we fabricate a metal nanowire grid polarizer to demonstrate a potential device application. The main advantage of this technique lies in its inherent self-aligned process that simplifies selective Au nano-patterning on non-planar polymer surfaces, which is otherwise difficult to be obtained using conventional patterning techniques.     

Scanning of skin gloss by a diffractive optical element-based handheld glossmeter

Skin specular gloss (referred to as “gloss’’) determination is important in dermatology and cosmetic industry as it gives an indication of the skin health and beauty. Its accurate determination is, therefore, necessary. Commercially available glossmeters typically employ large incidence angle geometry, large illumination area, and fixed point measurements making them impractical regarding measurement of curved and complex non-planar objects or surfaces as well as low gloss regime such as the skin. In this study, we have demonstrated the novel application of a diffractive optical element-based handheld glossmeter with scanning capability, overcoming the disadvantages of conventional glossmeters, in the accurate determination of skin gloss and gloss profile for different skin types under different measurement conditions. Different parts of the body (back of the hands, the inner part of the arm and the forehead) of four volunteers with light, dark and intermediate skin types were scanned (also in different directions) to obtain the skin gloss profile and the statistical average skin gloss. Additionally, the skin surface was modified by arm extension and scanned as well. Our preliminary results showed that the statistical average skin gloss reading increased with the increasing lightness of skin. Areas with higher sebaceous glands (forehead) showed higher gloss reading than the other body parts (inner arm and back of the hand). However, the roughness of the skin surface decreased the statistical average skin gloss reading. The handheld scanning skin glossmeter allows for the accurate determination of skin gloss with sensitivity to small variation in the skin surface roughness with high repeatability.     

Approximate solutions of radiative transfer in one-dimensional non-planar systems

An approximate method is developed for the study of radiative transfer in one-dimensional, non-planar systems. While this method can be regarded as an extension of some existing approximation techniques formulated for the one-dimensional planar problem, it does yield closed-form expressions for the radiant heat flux and the temperature profile for various non-planar problems, which have not been established before. Comparisons with the available numerical results show that the heat-flux expressions are accurate throughout the entire range of the optical thickness. Results for the temperature profile. however, have the same limitation as the various closed-form approximate solutions for the planar problem. They are not very accurate at regions near the boundary, except in the optically thick limit. Based on the closed-form expressions obtained for the non-planar radiative transfer problem, the present work establishes readily the effect of the various parameters, such as the optical thickness, the surface emissivity, the radius ratio and the heat-generation rate on the heat-transfer and the temperature profile. Differences between radiative heat-transfer characteristics of the two basic non-planar systems (concentric cylinders and concentric spheres) are discussed.     

随机粗糙微通道内流动特性研究

采用计算流体动力学的方法, 研究了微通道内气体在速度滑移和随机表面粗糙度耦合作用下的流动特性. 其中, 利用二阶速度滑移边界条件描述气体的边界滑移, 利用分形几何学建立随机粗糙表面. 研究发现, 综合考虑二阶速度滑移边界条件和随机表面粗糙度在较大的平均Knudsen数范围内 (0.025-0.59) 得到的计算结果与实验数据符合得很好, 而一阶速度滑移边界条件只在平均Knudsen数较小时(<0.1)符合实验结果. 随机表面粗糙度对气体在边界处的滑移有显著影响, 相对粗糙度越大, 速度滑移系数越小. 并针对计算结果, 给出了滑移系数与相对粗糙度近似满足的关系. 随机粗糙表面对气体流动过程中的压强、速度、Poiseuille数也有显著影响. 关键词： 随机表面粗糙度 二阶速度滑移边界条件 分形 微通道     

基于激光散斑成像的零件表面粗糙度建模

表面粗糙度是衡量机械表面加工水平的重要参数. 通过构建一套激光散斑成像采集系统, 获取了不同表面加工类型和不同粗糙度值的零件表面激光散斑图像. 应用Tamura纹理特征理论提取图像的纹理粗糙度、对比度、方向度特征, 并分析了这三个特征与表面粗糙度的关系. 发现了纹理粗糙度特征与表面粗糙度的单调关系, 推导出平磨、外磨、研磨三种表面加工工艺的粗糙度值与图像纹理粗糙度特征的数学函数关系, 实现了表面粗糙度的测量. 同时, 利用Tamura纹理特征与加工工艺的依赖关系, 建立了基于贝叶斯网络的工艺识别推理模型, 推理出了零件表面加工工艺. 通过为多种加工类型表面建立粗糙度测量模型, 为粗糙度测量提供了新思路. 实验证明所提的粗糙度测量模型能以较高的准确率识别出零件表面加工类型并测量出其表面粗糙度值.     

离子束作用下的光学表面粗糙度演变研究

 为了获得超光滑光学表面,介绍了离子束作用下改善表面粗糙度的抛光方法,并通过相关的实验进行了验证。光学材料是典型的硬脆材料,在加工过程中的表面粗糙度要经历复杂的演变过程。离子束加工作为光学镜面加工中的最后一道工序,如果在修正面形的同时,能够有效地改善表面粗糙度,那么离子束加工的性能就可以得到更好的延伸。分析了离子束作用下的粗糙度演变机理,在此基础上提出了倾斜入射抛光和牺牲层抛光技术2种改善表面粗糙度的方法,并使用原子力显微镜进行了测量。实验结果表明：以45°倾斜入射抛光熔石英样件,其粗糙度由初始的0.67nm RMS减小到0.38nm RMS;涂上牺牲层的材料表面粗糙度由0.81nm RMS减小到0.28nm RMS,倾斜入射抛光和牺牲层抛光技术能够有效地改善表面粗糙度。