粗糙集理论及其在图像处理中的应用*

首先描述了粗糙集理论的基本概念,包括粗糙集知识表示方法和粗糙集约简理论;叙述了粗糙集理论及其与其他非线性理论相结合在图像处理中的应用情况;最后指出了粗糙集理论应用于图像处理的基本思路,并指出将粗糙集理论与其他非线性理论相结合应用于图像处理,将会产生更加有效的结果.     

Microstructural modeling approach applied to rock material

The importance of the microstructural parameters in rock mechanical behavior has been investigated by several authors. Moreover, the Weibull statistical model has been used to characterize the heterogeneity of several materials on the basis of the concept that the microscopic defects within the material determine their mechanical strength. The modeling of different rocks is a topic that is fundamental for the prediction of rock fragmentation. In this article, the analysis of rock microstructure is performed using the microstructural modeling approach, which consists of the simplification, quantification, and modeling of the main properties of rock microstructure. The grain size, grain shape, and microcracks are modeled by means of statistical density functions, namely, Cauchy, chi-squared, exponential, extreme value, gamma, Laplace, normal, uniform, and Weibull. It is found that the Weibull distribution is the most appropriate statistical model of the grain size and grain shape, when compared with the other eight statistical models. Regarding microcracks, the results show that the gamma distribution is the most appropriate model. The Weibull and gamma distributions are then used to analyze the heterogeneity of the microstructure. This is done by comparison of the statistical models of each microstructural property evaluated in several thin sections of the same rock. It is found that with respect to grain size and grain shape, the rock is homogeneous, while the size distribution of the microcracks shows a clear trend toward less homogeneity. The microstructural modeling approach is important for modeling, characterizing, and analyzing the microstructure of rock material. Among other applications, it can be used to explain differences in the mechanical behavior obtained in testing several specimens.     

基于网络文本的山地景观游客行为与形象感知研究——以重庆市长嘉汇弹子石老街为例

剖析网络评价文本能为景观规划设计提供科学的依据支撑,弥补因快速城镇化建设发展而导致的公众参与不足,对于景观设计而言是非常重要的。以重庆市弹子石老街为例,基于网络文本内容分析法,利用rostcm6、excel及python等分析和数据抓取软件,采集大众点评的相关评论数据,以山地景观设计视角结合相关数据分析软件进行定性定量分析并制作可视化分析图,最终从多维度分析游客评论得出结果及改进建议,总结针对重庆弹子石老街及山地景观设计的6条设计策略:(1)交通可达的组织方式;(2)垂直上下的衔接转换;(3)对景远眺的外向空间;(4)本土文化的特色彰显;(5)城市事件的策划安排;(6)游览夜景的慢行系统,期望对今后的类似山地景观空间规划设计提供一定参考和借鉴价值。     

高铬铸铁中铌碳化物的辨认

介绍了用背散射象法、彩色金相法和扫描电镜分析区别铬碳化物和铌碳化物。     

梭式窑火焰数字图像的边缘检测初探

本文介绍了几种典型的边缘检测算法,对它们各自的特点进行了比较。对梭式窑内的一幅原始图像,可用边缘检测算法提取火焰图像的边缘。     

基于Bayes特征判别的选煤建模与识别

研究了煤块的Harr小波变换和幅度投影分析,在对原始图像进行特征判别分析的基础上,建立了煤块和煤矸石的统计模型,提出了用Bayes判别函数分选煤块和煤矸石的算法,实现了用计算机视觉系统对样本进行了识别检验.并运用神经网络BP算法进行训练识别,检验其正确性,最后通过实验验证了算法有效性.     

Augment low-field intra-operative MRI with preoperative MRI using a hybrid non-rigid registration method

Background

Preoperatively acquired diffusion tensor image (DTI) and blood oxygen level dependent (BOLD) have been proved to be effective in providing more anatomical and functional information; however, the brain deformation induced by brain shift and tumor resection severely impairs the correspondence between the image space and the patient space in image-guided neurosurgery.

Method

To address the brain deformation, we developed a hybrid non-rigid registration method to register high-field preoperative MRI with low-field intra-operative MRI in order to recover the deformation induced by brain shift and tumor resection. The registered DTI and BOLD are fused with low-field intra-operative MRI for image-guided neurosurgery.

Results

The proposed hybrid registration method was evaluated by comparing the landmarks predicted by the hybrid registration method with the landmarks identified in the low-field intra-operative MRI for 10 patients. The prediction error of the hybrid method is 1.92 ± 0.54 mm, and the compensation accuracy is 74.3 ± 5.0%. Compared to the landmarks far from the resection region, those near the resection region demonstrated a higher compensation accuracy (P-value = .003) although these landmarks had larger initial displacements.

Conclusions

The proposed hybrid registration method is able to bring preoperatively acquired BOLD and DTI into the operating room and compensate for the deformation to augment low-field intra-operative MRI with rich anatomical and functional information.     

Fall detection for multiple pedestrians using depth image processing technique

A fall detection method based on depth image analysis is proposed in this paper. As different from the conventional methods, if the pedestrians are partially overlapped or partially occluded, the proposed method is still able to detect fall events and has the following advantages: (1) single or multiple pedestrian detection; (2) recognition of human and non-human objects; (3) compensation for illumination, which is applicable in scenarios using indoor light sources of different colors; (4) using the central line of a human silhouette to obtain the pedestrian tilt angle; and (5) avoiding misrecognition of a squat or stoop as a fall. According to the experimental results, the precision of the proposed fall detection method is 94.31% and the recall is 85.57%. The proposed method is verified to be robust and specifically suitable for applying in family homes, corridors and other public places.     

基于多混沌系统的彩色图像加密方法

为了提高彩色图像加密的安全性和加密性能,设计了一种基于多混沌系统的彩色图像加密方法.将一个彩色图像分解为R、G、B三个灰度图像,使用MD5算法动态生成加密算法的初始值,然后使用三种不同的基于混沌的加密结构对三个图像进行加密.对R图像使用Feistel结构加密,其中Feistel结构的S一盒由Logistic混沌序列和Hyperhenon混沌序列组合产生;对G图像使用由Lorenz系统产生加密序列对图像进行代替和置换操作的加密结构;对B图像使用由分段线性混沌映射产生加密序列,然后加密图像的加密结构,再把加密后的图像结合起来生成加密后的图像.理论分析和实验结果表明,该加密方法能够较为有效地保证彩色图像加密的安全性.     

基于Gabor多尺度空间的不变兴趣点检测

针对以往仿射不变兴趣点的特征尺度不能直接断定的问题, 提出一种基于Gabor多尺度空间的不变兴趣点检测算法。该算法主要包括三个步骤：应用Gabor滤波器组与图像卷积建立图像Gabor多尺度空间; 通过极大值准则检测兴趣点并直接断定特征尺度; 采用二阶矩矩阵描述兴趣点局部结构。实验结果表明, 相比较其他Hessian-Affine、MSER等算法, 该算法在图像模糊和JPEG压缩情况下可重复率和可匹配率均取得最好结果, 是一种能有效直接提取特征尺度的兴趣点检测算法。