激光光条中心线提取研究综述

激光光条中心线提取在视觉测量、三维重建等领域具有重要的作用.介绍了不同类型的中心线提取模型,并且回顾了这些模型的转变和创新.具体来说,根据模型采用的核心算法,将中心线提取模型分为传统提取模型和基于深度学习的提取模型;传统中心线提取模型又分为极值模型、灰度重心模型、曲线拟合模型、基于Hessian矩阵的Steger模型和可变方向模板模型;结尾从优缺点及其克服的问题等角度对比分析了不同类型的算法模型.分析表明传统激光光条中心线提取算法在图像的适应性和处理的实时性上有较为明显的不足,指出光条中心线提取模型的发展应逐渐偏向于灵活性、泛化性、实时性更强的深度学习领域.     

球B样条曲线结合树状结构的脑血管表示模型

针对分割之后的脑血管体数据场,提出基于球B样条曲线结合树状结构的表示模型.该模型中主要分为3个步骤表示脑血管:首先采用Hessian矩阵结合弹性球的方法获取脑血管的中心线和半径信息,可提高中心线的求取精度并且在中心线的求取过程中即可获得半径;然后对获得的中心线和半径进行树状重构,得到符合血管的形态拓扑结构,便于对脑血管进行遍历;最后对重构之后的每一分支血管采用球B样条曲线的方式来描述,以对脑血管病变区域进行检测,并能针对不同大小的显示窗口采用多尺度方式绘制.实验结果表明,文中模型在脑血管的显示、病灶检测等方面具有极大优势.     

结肠中心线快速提取算法研究

中心线的提取速度是提高结肠计算机辅助检测的效率的重要因素.为此提出了一种基于生成树的中心线快速提取算法(FMST).在分析了最大生成树中心线提取算法(MST)存在大量冗余数据特点的基础上,利用边主源辅的搜索策略,保留趋于物体中心的关键点,通过消减冗余数据的方法来提高MST算法的速度.在10套已知中心线金标准的结肠仿真数据和2套结肠CT数据上的实验结果表明,FMST算法加快了MST算法的提取速度并且保持了中心线提取的准确性;在仿真数据上,FMST算法较MST算法的速度提高了80％以上,中心线重合率达到96.98％.     

基于最小代价路径的血管中心线提取

为解决传统最小代价路径算法提取血管中心线时存在偏向血管侧壁的问题,提出一种基于点的中心线校正方法。应用最小代价路径算法初步提取中心线,然后根据血管剖面灰阶值呈高斯分布的特点对每个中心点进行校正,再利用三次B样条将离散的中心点拟合为一条连续的中心线。实验结果表明,该算法提取的中心线更靠近血管的中心处,且对噪声具有鲁棒性。此外,将该算法用于起点、终点位置的校正,则提取的中心线对用户定义点的位置不敏感。     

基于曲线拟合的Placido图像中心提取方法

中心提取是Placido图像特征提取的关键环节,提出了一种基于曲线拟合的中心定位方法。利用Hough变换定位图像的像素级中心,建立图像的极坐标系;在极坐标轴方向,通过亮环灰度变化曲线的导数特征检测亮环中心线;将亮环中心线进行曲线拟合,确定亮环中心位置。中心提取精度达到亚像素级,利用标准球验证算法精度,屈光度误差小于0.25D。与常规算法进行对比,分析结果表明,曲线拟合法在准确性和稳定性上更优,为绘制精确的角膜地形图提供了保证。     

基于改进边界距离变换的路径提取算法研究*

针对虚拟内窥镜中心路径提取算法时间效率不高的问题,通过改进边界距离变换,提出了中心路径的快速提取算法。首先建立最小距离场,在边界内推过程,仅扫描并处理与边界点面连接的点并对其设标记属性,每次向里剥离一层体素标记属性随之增加,直到对内部点集都置到边界的最小边界距离值（DFB）;然后找到DFB值不小于其所有面邻接点DFB值的体素点,即3D局部最大值;最后用最短路径相连3D局部最大值,形成中心线。实验结果表明,改进的中心路径提取算法的时间效率较传统距离变换算法有很大提高。     

一种新的血管造影图像Hessian矩阵增强算法

针对实际血管造影图像存在的噪声和光照不均,本文提出一种新的Hessian矩阵增强算法来提取血管图像。算法主要通过无抽样方向滤波器组进行血管方向图分解、同态滤波器滤波、Hessian特征矩阵和血管方向图合成。实验表明,与传统Hessian算法相比,提出的算法能够连续提取血管的精细结构,对噪声不敏感,处理的图像质量更高。     

一种新的肺结节检测算法

为了能够在肺癌早期或者例行体检时及时发现肺部结节灶,临床上要求能够对肺结节进行全面迅速的检测。提出了一种新的肺结节检测算法——TMH（引入了Hessian矩阵的模版匹配）算法。该算法首先获取肺实质;然后在二维层面上采用模版匹配方法（Template-Matching,TM）对结节进行检测;最后引入Hessian矩阵,有效降低了原TM算法的假阳率,实验证明该算法能够快速检测出肺结节,且假阳率较小。     

自适应回声对消的初期迭代统计学模型及改进算法

为减少滤波器长度,提出自适应滤波算法初期迭代统计学模型及改进的回声消除算法。提出的统计学模型分析了自适应算法迭代初期滤波器各系数的均值和方差。基于该模型提出的改进算法,先检测回声路径峰值,进而确定回声路径延时,然后以延时为中心,用一个短的滤波器辨识原回声路径活跃系数部分。用实际回声路径进行仿真,理论和实验结果均表明,新算法在迭代的前75～100步已可准确检测回声路径峰值并确定延时;而减少滤波器长度,可大幅提高自适应算法收敛速度并降低算法计算复杂度。     

改进的边界距离变换算法在虚拟内窥镜中应用

为提高虚拟内窥镜实现中提取中心路径的时间效率,改善虚拟内窥镜的实时漫游,边界距离变换算法是提取中心路径的常用算法.上述算法在建立边界距离场和源距离场时非常耗时,故实时性很差.针对建立两个场非常耗时的缺点,提出定义超大数组,建立体素点ID值和体素点在体素点集中位置的一一对应关系,减少在确定体素点位置时对体素集的扫描次数,从而提高算法的效率.实验结果表明,改进后的算法时间效率高,实时漫游效果好,速度快,提取的中心路径漫游效果好,实现了虚拟漫游效果,具有一定的实际应用与理论研究价值.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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