基于CT图像的自动肺实质分割方法

在肺癌、肺气肿等肺部疾病计算机辅助诊断方法中,肺实质分割是最核心的步骤.提出一种基于三维CT图像序列的新的自动肺实质分割方法,综合利用了阈值分割、区域增长及数学形态学等算法,并在特定体层通过图搜索算法精确定位左右肺前后连接线狭窄区域,有效解决了肺实质边缘结节易分割遗漏及左右肺分离的难题.通过多组胸部CT序列图像的实验证明,该方法对于肺实质分割非常精确有效.     

基于区域增长算法分割DICOM格式的CT肝脏图像

在计算机辅助诊断中,为减少数据损失与处理时间,直接从DICOM格式的CT腹部图像中分割肝脏组织.利用区域增长算法自动分割CT肝脏,并和医生手工分割的肝脏图像做对比.分割的肝脏图像与原图像相比,自动分割的肝脏和原图像肝脏接近一致,得到较为满意的效果.区域增长分割算法能从胸腹腔CT图像中分割出保留灰度的肝脏,为CT图像的计算机辅助诊断起到了重要的作用.     

采用改进Snake模型的胸片肺野自动分割方法

为了解决传统Snake模型应用于X光胸片肺野分割时,对人工初始化轮廓的选择敏感、对凹陷区域分割不准确等问题,提出一种基于自动初始化Snake模型的X光胸片肺野自动分割方法.该方法首先通过Otsu法对原始图像进行二值化,得到包含肺野、背景区域的二值图像,并经过图像取反和连通域处理,运用形态学方法,得到只含有肺野区域的二值图像;然后,通过边界提取,完成对Snake模型轮廓的自动初始化;最后通过Snake模型的演化,得到分割结果.实验结果表明:该方法能摆脱Snake模型对人工初始化轮廓的依赖,提高分割的鲁棒性,同时对凹陷区域的分割更准确,具有更好的分割效果.     

CT图像中肺结节毛刺特征的计算机量化方法

根据CT图像中肺结节毛刺的生长特点,提出了一种CT图像的肺结节毛刺特征计算机量化分级方法.该方法首先利用动态规划算法对感兴趣的CT图像区域进行肺结节分割,然后在分割的结节边界基础上,通过分析边界附近区域梯度方向的规律性,提取边界法线-梯度正交指数作为结节毛刺特征的量化指标,在此基础上对肺结节毛刺特征进行量化分级.实验结果表明:该指数能够准确地量化肺结节的毛刺特征,对区分无毛刺、短毛刺及长毛刺结节具有较高的分辨率.     

基于随机游走算法的CT图像肺肿瘤分割

针对CT图像肺肿瘤分割中复杂大肿瘤分割的准确性和自适应问题,提出了一种基于随机游走算法的分割方法.首先,根据图像灰度信息提取肺实质;针对大肿瘤与周围肺组织粘连的复杂情况,先提取有凹陷的肺实质,再根据肺实质先验轮廓,用曲线段形变模型修补肺实质的凹陷边界.然后,用区域生长法自动确定目标种子点和背景种子点;对于大血管与肿瘤粘连的情况,需要少量交互修改个别背景种子点.最后,用随机游走算法完成大肿瘤的分割.实验结果表明,该方法的准确性高,分割结果能够满足临床治疗效果分析和病理学研究的要求.     

基于数学形态学的医学图像自动阈值分割

提出了一种自动分割癌细胞图像的方法.该方法利用数学形态学开运算型边缘检测算子对图像边缘锐化;利用邻域平均与中值滤波方法平滑图像;利用改进的判别分析法自动选取灰度阈值进行图像自动分割;利用自动分割区域与手动分割区域的误差和平均最短距离对自动分割效果进行评价.用该方法对20幅癌细胞图像进行自动分割实验,证明了其对图像分割的有效性.     

基于形状分析的肺部疑似粘连肿瘤检测

肺部疑似粘连肿瘤的自动检测是肺区分割的关键步骤。提出一种利用肺区轮廓的形状特征及序列图像的相似性检测粘连肿瘤的方法。首先在CT序列中的每幅图像上定位肺区轮廓。然后分析轮廓形状,检测出包含肿瘤的CT图像。最后,用CT序列中与之相邻的正常图像轮廓来近似肿瘤侵占之前肺区轮廓。比较侵占前后的轮廓线形状差异检测出肿瘤区域,区域生长定位肿瘤。实验结果表明该方法能够有效的实现肿瘤自动检测和分割。     

一种基于CT图像的肺实质分割方法

在肺部疾病的计算机辅助诊断(CAD)时,肺实质的正确分割尤为重要.为了减少检测区域,节省运算时间,提高准确率,需要预先提取肺组织.提出了一种改进的最大类间方差法(OTSU)结合形态学运算的肺实质分割方法.首先对原始CT图像做滤波去噪、图像增强的预处理,自适应阈值二值化图像;然后连通区域标记获取轮廓,利用基于OTSU的改进算法去除气管、肺液等干扰,分离肺实质与背景,对左右肺叶粘连的情况采用行列扫描、区域彩色标记并将其有效分离;最后采用一系列的形态学运算对提取出来的肺实质弥合修补.从公开数据库LIDC中选取830张CT图像,用该方法可完整分割肺实质,平均准确率为97.56%,平均召回率可达99.29%,Dice相似系数为98.42%.     

基于改进的大津方法与区域生长的医学图像分割

提出了一种自动分割边缘模糊图像的新方法.该方法利用小波变换对图像进行压缩与多解像度分解,通过强调各解像度上高周波成分的极值进行图像锐化;利用邻域平均与中值滤波方法对图像进行平滑;利用改进的大津方法与多种子投票机制的区域生长方法进行图像的自动分割;根据分割效果对阈值进行迭代控制;通过自动分割的区域与影像医生手动分割区域的误差、平均最短距离进行自动分割效果的评价.将本方法应用于实际的30幅边缘模糊的腹部MRI图像,证明了其对复杂图像分割的有效性.     

基于分形几何和最小凸包法的肺区域分割算法

在计算机辅助诊断系统中,为了缩小系统的分析范围、提高计算效率,需要将肺区域分割出来.但是通过已有方法获得的肺区域边界不准确,为此提出了一种基于分形几何和最小凸包法的肺区域分割算法.首先,根据肋骨和各组织的位置关系以及CT图像的上下层相似的性质,实现了对初始肺区域的自动提取.其次,利用网格线将肺区域分成小子块,并计算各子区域块的分形维数.根据肺区域边界的全局性质和局部性质,构造了最优的分形维数阈值,并根据该阈值识别需要修复的肺边界.最后,利用Jarvis步进法对肺边界进行了修复,从而在CT图像中获得了最终的肺区域.通过数值实验证明了提出的算法比传统方法更优秀,具有较高的分割准确率和较高的鲁棒性.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to