基于标签化医学图像的多阈值三维重建算法

针对传统面绘制重建方法 MC无法一次性提取多个阈值器官的问题,提出一种将MRI图像中靶区及其周边组织进行标签化分割的多阈值三维重建算法。该算法通过将二维图像中的多阈值器官标签化为简单的整数,降低提取等值面时的数据存储量,进而提高等值面的绘制速度。同时,定义了多阈值三维重建时体素顶点索引方式和等值面相交形态,减少了传统MC算法提取多个阈值器官时存在三角面片与顶点复用的情况,且仅需一次性扫描即可重建多个器官等值面。实验结果表明,本文算法较传统MC算法,重建器官数量越多,器官彼此结构越紧密,三角面片与顶点复用情况减少越明显,在保证重建效果的同时,绘制速度可提高30%。     

MC 算法在 CT 医学图像三维重建中的应用*

MC 算法是三维重建面绘制的经典方法,采用等值面提取的方式把所需的数据分离出来进行重建。通过对 MC 算法的原理进行分析,结合 VTK 类库编程,研究基于 MC 算法提取CT 图像病灶的方法,并通过坐标平滑的方法对算法进行改进,提高三维重建的平滑显示效果和重建速度。     

改进标记分水岭的乳腺X线图像肿块检测方法

乳腺X线图像肿块大小不一,固定参数的传统标记分水岭算法无法实现乳腺X线图像肿块的有效检测。针对此问题,文中提出了一种结合形状特征和改进型标记分水岭的乳腺X线图像肿块检测方法。在计算前景标记时,结合标记的形状特征判定前景标记,通过对前景标记进行形态学膨胀并提取边缘以获得背景标记,利用改进型自适应参数标记分水岭算法实现肿块检测。实验结果表明,文中算法通过结合形状特征,自适应地选择合适的形态学参数,使得肿块检测准确率高于传统标记分水岭算法。     

视点相关排序的硬件Occlusion查询MC算法

移动立方体(MC)算法是一种高质量的面绘制方法,要对大量三角面片实现实时绘制和交互操作,因而速度慢,交互性不好;提出一种方法利用显卡硬件实现Occlusion查询,将MC算法生成三角面片分割标记到不同的cube后,基于视点距离对cube进行先后Occlusion查询,检测并剔除对最终图像没有贡献的三角面片;实验数据表明,提出的方法对大规模体数据集进行表面绘制,绘制速度和交互性都得到了明显提高.方法应用在"高级三维PACS工作站"系统上,进行医学CT图像的三维重建表面绘制,取得了良好的效果.     

工业CT数据场面绘制和体绘制改进算法研究

工业CT图像的重建速度和精度是工业CT产品的两个重要指标。针对面绘制的MC算法提出了一种基于相似性区域分割的三维工业图像表面重建算法,实现了准确分割,并利用分割结果精确地提取等值面,显著提高了检测效率;针对体绘制的光线投射算法提出了一种基于二维最大熵阈值的分割预处理方法,利用二维直方图熵最大化寻找阈值的最佳组合,能有效减少重建体数据量,实测数据表明体绘制速度明显提高。     

基于最近邻Marching Cubes的医学图像三维重建

在医学图像三维可视化中,移动立方体算法（Marching Cubes,MC）是面绘制的经典算法。针对MC算法计算插值点导致执行速度慢、效率不高的缺点,提出一种基于最近邻逼近的MC算法,该方法在n次等分点量化序列中寻找等值面最近邻点代替线性或非线性插值,既避免了插值的大量计算又保证了误差精度,还可改善三角面片结构。利用可视化工具开发包VTK对人体脸部和脚部CT数据集进行三维重建,实验表明改进算法明显缩短了绘制时间,提高了重建效率。     

脑部MRI图像头皮三维提取及重建

开颅手术中,为了满足手术导航系统进行快速、准确定位的要求,提出一种脑部核磁共振成像(MRI)图像三维头皮轮廓提取方法。首先采用各向异性扩散滤波方法对图像滤波,借助BrainSuite3医学软件获取脑标记图像;然后将图像中脑实质部分剔除,根据非脑组织图像计算头皮组织的分割阈值;再利用数学形态学处理二值图像获取头皮轮廓;最后结合目标灰度信息,用移动立方体(MC)算法进行三维重建。实验结果表明,该方法结合阈值、数学形态学和MC算法,能连续、光滑地提取出头皮外轮廓,并使精度达到亚像素级别。     

面绘制三维重建原理及其改进算法研究

Marching Cubes(MC)算法是经典的面绘制算法,但它存在数据源复杂、分割方法单一和三维网格存储量大的问题.针对这种情况,提出了改进策略,主要是从图像预处理、图像分割及三角形网格简化方面加以讨论,并给出了相应的算法,由此使得重建算法的数据源信息更准确,适用面更广,存储效率更高.     

乳腺X线图像中致密区域肿块的检测算法

提出一种在乳腺X线图像中致密区域肿块的检测算法.该算法根据乳腺致密区域肿块内核灰度一致性的特点,利用小波多尺度分析特性,在小波域的高频子带进行疑似肿块区域的搜索和定位;再借由分形维数对图像灰度表面粗糙度刻画能力对可疑病灶区判别筛选:最终针对致密区域肿块与正常腺体界限模糊的特性采用结合模糊理论的区域生长算法提取出保持关键诊断信息的肿块病灶区域.实验表明,提出的算法在乳腺致密区域肿块自动定位、肿块病灶区域边缘形态刻画等方面较传统算法有较大改进,能为后续的计算机辅助诊断决策判决提供有效全面的分析数据.     

双侧特征融合的乳腺肿块检测

乳腺癌是妇女最常见的恶性肿瘤之一,面向乳腺钼靶X线图像的计算机辅助肿块检测技术可以帮助影像科医师早期发现乳腺病变.针对于单侧的乳腺肿块检测中准确率有待提升的问题,提出双侧特征融合的乳腺肿块检测算法.首先,进行图像预处理,并利用相干点漂移完成乳腺轮廓配准;然后,利用配准得到的变换矩阵获得双侧乳腺感兴趣区域,再在其中提取左右侧乳腺的单侧特征向量和双侧对比特征向量,从而建立融合的特征模型,并采用遗传选择算法对特征向量进行特征选择;最后利用极限学习机基于选择后的特征进行乳腺肿块检测.实验结果表明,与传统的基于单侧的乳腺肿块检测算法相比,文中算法能有效地提高检测准确率.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.