基于自适应传播机制的红外图像快速增强算法

针对传统的红外图像对比度增强方法存在的运算速度慢、增强效果不佳的问题,提出了一种基于自适应传播机制的红外图像对比度快速增强算法。首先使用自适应传播机制求出红外图像的各种局部空间信息,然后对各种信息进行非线性拉伸调整,得到增强后的图像。最后,比较和分析了几种增强算法实验结果,证明了本方法快速高效的优异性质。     

Optimized contrast enhancement for tumor detection

Magnetic resonance imaging (MRI) is a real assistant for doctors. It provides rich information about anatomy of human body for precise diagnosis of a diseases or disorder. But it is quite challenging to extract relevant information from low contrast and poor quality MRI images. Poor visual interpretation is a hindrance in correct diagnosis of a disease. This creates a strong need for contrast enhancement of MRI images. Study of existing literature shows that conventional techniques focus on intensity histogram equalization. These techniques face the problems of over enhancement, noise and unwanted artifacts. Moreover, these are incapable to yield the maximum entropy and brightness preservation. Thus ineffective in diagnosis of a defect/disease such as tumor. This motivates the authors to propose the contrast enhancement model namely optimized double threshold weighted constrained histogram equalization. The model is a pipelined approach that incorporates Otsu's double threshold method, particle swarm optimized weighted constrained model, histogram equalization, adaptive gamma correction, and Wiener filtering. This algorithm preserves all essential information recorded in an image by automatically selecting an appropriate value of threshold for image segmentation. The proposed model is effective in detecting tumor from enhanced MRI images.     

基于形态分析法的中国北方游牧民族饮器造型元素提取及应用研究

目的 探析中国北方游牧民族饮器造型再设计应用方法。方法 采用实证研究的方式,通过焦点小组方法建立中国北方游牧民族饮器的语义感知评价量表,并进行问卷调查。运用形态分析法解构中国北方游牧民族饮器造型元素,建立反应矩阵。以数量化Ⅰ类理论数据分析方法为基础,构建语义感知评价与各造型元素之间的对应关联模型。结果 共有16种中国北方游牧民族饮器造型元素对使用者的语义感知评价产生了显著影响,每种造型元素可对不同的语义感知评价产生正向或负向影响。结论 应用语义感知评价与中国北方游牧民族饮器造型元素的对应关联模型,可以快速帮助设计师找到针对不同的用户需求产生正向影响的造型元素,规避产生负面影响的造型元素。为中国北方游牧民族饮器造型再设计提供了高效的指导路径。     

连续太赫兹波数字全息相衬成像

太赫兹波具有独特的低能性、高穿透性、惧水性等成像特性,将其应用于相衬成像能够反映物体的内部结构和更加丰富全面的生物信息,在生物医学检测等领域具有重要的应用。其中,太赫兹波数字全息成像是一种可以给出定量的振幅和相位信息的非接触、全场相衬成像方法,是太赫兹成像技术领域的重要研究方向之一。本文基于连续太赫兹源,从离轴式和同轴式数字全息成像的相衬成像原理、光路系统和再现算法多个方面,介绍了相关技术的研究现状,分析了太赫兹源、再现算法等因素对成像分辨率的影响,并对太赫兹数字全息的发展趋势进行了展望。     

基于多尺度形态学操作的超声图像增强方法

针对医学超声图像低对比度和强噪声给医疗诊断和图像处理所带来的困难，通过基于多尺度形态学操作的方法实现图像增强和噪声抑制的目的．该方法将传统的图像增强概念延伸到数学形态学多尺度空间中，利用多尺度形态学操作提取图像多尺度特征，并通过改变这些特征的强度实现图像局部对比度增强和噪声抑制．实验证明，该方法对超声图像局部对比度增强和噪声抑制是有效的．     

Medical image enhancement algorithm based on NSCT and the improved fuzzy contrast

In order to solve the problem of noise amplification, low contrast and image distortion in the process of medical image enhancement, a new algorithm is proposed which combines NSCT (nonsubsampled contourlet transform) and improved fuzzy contrast. The image is decomposed by NSCT. Firstly, linear enhancement method is used in low frequency coefficients; secondly the improved adaptive threshold function is used to deal with the high frequency coefficients. Finally, the improved fuzzy contrast is used to enhance the global contrast and the Laplace operator is used to enhance the details of the medical images. Experimental results show that the proposed algorithm can improve the image visual effects, remove the noise and enhance the details of medical images. © 2015 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 25, 7–14, 2015     

Hamilton's law of variable mass system and time finite element formulations for time‐varying structures based on the law

Traditional principles of mechanics are primarily conceived for constant mass systems, which are only valid if mass is gained or lost at null velocity with respect to an inertial reference frame for variable mass systems, thus the numerical algorithms for time‐varying structures based on these principles are only suitable for this special case. In this paper, Hamilton's law of variable mass system is derived based on Meshchersky's fundamental equation, and two classes of novel time finite element formulations for linear systems with arbitrary continuous time‐varying parameters are developed based on the previous law. The formulations are verified extensively through numerical examples in which the convergence and effectiveness of algorithms are evaluated. Numerical examples demonstrate that compared with the algorithms for time‐varying structures that developed based on traditional principles of mechanics, the proposed algorithms provide extended capabilities in both time‐varying mass problems that mass is gained or lost at any velocity (such as rocket problem) and moving‐mass problems (such as vehicle‐bridge interaction problem) besides the time‐varying stiffness and damping problems, the proposed algorithms have a wider range of application. In particular, Hamilton's law of variable mass system provides a solid theoretical foundation for further research on the algorithm design for time‐varying structures. Copyright © 2014 John Wiley & Sons, Ltd.     

Capability index of a complex-product machining process

A complex product often requires a high machining precision. This is often achieved by a close-loop machining process to be carried out in several stages, and the measurements, fixture adjustments, and feedback or feed-forward control are inserted after each of these stages. The Complex Product Machining Process (CPMP) Capability Index (CPMPCI) is affected by the control and adjustments in a CPMP, and hence the calculation results of CPMPCI can be used as references to select a proper CPMP. In this paper, we present a novel calculation method of CPMPCI as quality control and improvement technology in a CPMP. A linear model is proposed for describing the variation propagation effect throughout all stages in a CPMP, and an observation model with the pre-specified control and adjustment strategy is employed to calculate the process mean and variation during a CPMP. Finally, through application of Taguchi's quality loss function, the CPMPCI calculation method is derived. The feasibility and effectiveness of this method are validated by a case study on a three-stage CPMP.     

Adaptive contrast enhancement based on histogram modification framework

ABSTRACT

An adaptive contrast enhancement method is proposed in this paper. The proposed method is based on the contrast limited adaptive histogram equalization (CLAHE) and the histogram modification framework. The predefined clip point for the clipped histogram of each block in original CLAHE may still result in excessive contrast enhancement in homogeneous regions, which gives the enhanced image an unnatural look and creates visual artifacts. By replacing the clipped histogram with a modified histogram, the proposed method achieves success in adaptively enhancing contrast in each block based on its content. In addition to this, a novel mapping function is introduced to further improve the enhanced result of histogram equalization (HE). Experiments are conducted with both visible images and infrared images to evaluate the performance of the proposed method. The results show that the proposed method gets better performance on contrast enhancement and visual quality of the enhanced results.     

结合基元对比度与边界先验的显著性区域检测

研究了对完成计算机视觉任务有重要作用的视觉显著性检测,考虑到单纯依靠对比度计算进行显著性检测具有一定的局限性,提出了一种结合基元对比度与边界先验信息的显著性区域检测算法。该算法通过Mean-Shift分割构造图像基元结构,以图像基元为基础,利用图像颜色和亮度两种特征获得基元对比度显著图,再利用图像边界先验条件得到边界显著图;为了突出显著性目标,采用一种新的融合方式将以上检测结果进行融合,最后对显著图像进行多尺度增强操作,以获得更加高质量的显著性图。在国际公开数据集上的实验表明,该算法与现有的较成熟的方法相比,基本符合人眼的主观判断,具有较高的精度召回率。     

Process capability index for Poisson regression profile based on the Spmk index

In many process control applications, the quality of a process or a product can be characterized by a functional relationship between a response variable and one or more explanatory variables which is typically referred to as a profile. Such profiles can be expressed by a linear or a non-linear model. On the other hand, for an in-control process, capability indices are used for process quality improvement. In this article, we propose a method to measure the process capability when the quality of the process is characterized by a Poisson regression profile. The performance of the proposed index is evaluated through simulations studies. Two real data examples illustrate this method.     

基于自适应形态滤波的医学超声图像降噪

针对医学超声图像上的斑点噪声,本文提出一种基于自适应形态滤波的降噪方法.首先构造一组检测图像中不同像素值突变的结构因子;再对每个结构因子构造相应的形态滤波结构元;最后对每个像素点邻域进行结构检测,找到该点处最可能存在的突变结构,以相应的结构元完成该点的形态滤波.对不同信噪比的仿真图像和实际图像分别采用本文方法和各向异性扩散滤波,不同尺度传统形态滤波进行了:比较实验,结果表明:采用本方法可将超声图像的信噪比、对比度噪声比和图像优度分别平均提高15%、37%和69%,优于其它方法.     

Assessment of a capability index sensitive to skewness

For many quality characteristics, such as circularity, cylindricity, straightness and flatness, positive skewness in the inspection data is the norm, and, in fact, is desirable. Summarizing the process performance using such data in conjunction with capability indices has recently received a considerable amount of attention, with new indices being proposed and compared for usefulness and accuracy. This paper is intended to contribute to this growing discussion, and to add a unique focus. In particular, this investigation concentrates on one form of a neoclassical index, the Cs index, originally proposed to be sensitive to skewness and to decrease in value as the skewness increased in the underlying distribution of the data. In other words, ‘skewness is badness’. Looking at this index from an altered perspective, the possibility that this index could serve a useful purpose in summarizing process performance for such non‐normal processes by merely changing its interpretation or slightly changing its form is considered. Hence, actual data from circularity measurements are used to identify a relevant group of distributions, and then the accuracy of C_s is investigated along with its modified version for this group of distributions. In particular, this investigation includes several Rayleigh and gamma distributions for various sample sizes and reports on the bias of the proposed estimators. These findings indicate that such a modified index has some useful attributes in reflecting process performance, with respect to the percentage of non‐conformance and the accuracy for relatively large samples. Copyright © 2001 John Wiley & Sons, Ltd.     

基于WDFB及形态膨胀的图像压缩算法

将小波和方向滤波器组结合,实现了一种非冗余的图像变换WDFB,它满足各向异性尺度关系,能更稀疏地表示诸如边缘和纹理等几何特征.利用WDFB的优势,提出一种基于形态学操作的有效的图像压缩算法.该算法利用重要树来表达子带间的相关性,同时采用形态膨胀算子来聚类子带内的重要系数.实验结果表明,新算法在PSNR指标上明显优于基于小波的压缩算法,尤其对于含有丰富纹理的图像.例如对于512×512的Barbara图,在0.25bpp压缩率下,新算法比SPIHT和MRWD算法的PSNR分别提高1.08dB和0.87dB.     

基于提升格形态小波的生物芯片图像增强

提出一种使用提升格形态小波进行生物芯片图像滤波增强的方法。根据生物芯片图像的样点和噪声区域的大小选择合适的结构元素或者预测-升级算子,并通过形态学算子或者提升格构造形态小波分解和重构形式。利用形态小波的不同级连方式和高频系数的处理实现生物芯片图像的滤波增强。实验表明,该方法可以有效地结合形态学和小波滤波的优势,降低了运算量,取得良好的生物芯片图像增强效果。     

基于可靠指标的稳定安全系数探讨

桥梁结构当第一类稳定安全系数取4时,能否保证结构在更可能出现的第二类失稳发生时的可靠指标达到目标可靠指标值得研究。对单层单跨刚架桥分别进行了第一类和第二类稳定计算,以第一类稳定计算得到的临界荷载,取第一类稳定安全系数为4,采用一次可靠度方法编制程序得出可靠指标。进而采用第一类稳定可靠指标计算时的荷载效应和第二类临界荷载来计算第二类可靠指标。根据可靠指标探讨结构稳定安全系数取值的合理性。在此基础上,对两类稳定临界荷载进行了参数分析,研究临界荷载的变化对可靠指标的影响。结果表明:稳定分析应区分失稳状态,第一类稳定安全系数取4,但当结构发生第二类失稳时,有些情况下不足以保证可靠指标达到目标可靠指标。     

一种基于索引数组的频繁项集高效挖掘算法

为改进基于数据库垂直表示的频繁项集挖掘算法的性能,给出了用索引数组方法来改进计算性能的思路.提出了索引数组的概念及其计算方法,并提出了一种新的高效的频繁项集挖掘算法Index-FIMiner.该算法大大减少了不必要的tidset求交及相应的频繁性判断操作,同时也论证了代表项可直接与其包含索引中的所有项集的组合进行连接,这些结果项集的支持度均与代表项的支持度相等,从而降低了这些频繁项集的处理代价,提高了算法的性能.实验结果表明,Index-FIMiner算法具有较高的挖掘效率.     

Numerical calculation of grounding system in low‐frequency domain based on the boundary element method

A new mathematical model for accurately computing currents flowing along the high‐voltage ac substation's grounding system and nearby floating metallic conductors buried in the multilayer earth model has been developed in this paper, which is a hybrid of the Galerkin‐type boundary element method (BEM) and the conventional nodal analysis method. Only the propagation effect of electromagnetic waves within the substation's limited area has been neglected in this model. The quasi‐static complex image method and the closed form of Green's function are introduced into this model to accelerate the mutual impedance and induction coefficients calculation. The model is then implemented in a computer program, which can be used to calculate current distribution of any configuration of the grounding system, with or without floating metallic conductors'. Copyright © 2007 John Wiley & Sons, Ltd.     

字符形态特征的机械仪表判读算法

基于字符形态特征提出一种快速的机械仪表判读算法.该方法中采用平滑滤波对灰度化后的图像去除噪音,再使用OTSU算法进行二值化,同时根据图像投影确定表盘区域,最后将Canny算子和Hough变换结合对图像进行矫正并分割字符.字符判读模块中对图像进一步去除噪音,对字符形态特征进行加权计算和对比,准确识别出仪表示值.通过实验证明,该算法辨识率高,有较好的实用性.     

一种新的基于粗糙集的数学形态学算法及其在图像边缘检测中的应用

从粗糙集的角度出发来研究数学形态学,指出经典数学形态学模型是不符合实际的,引入粗糙集中的粗糙度的概念改进了形态学模型,通过动态的选择结构元素来对图像进行处理.实验显示,基于粗糙集的数学形态学方法较好地解决了经典形态学处理中图像目标边界线条较粗的缺点.相比经典梯度算子,文中提出的方法又较好地保证了图像边界的连续性,同时还避开了结构元素的选择问题.