基于二类切比雪夫正交多项式非参数混合模型的图像分割

有参混合模型需要假设模型为某种已知的参数模型,而实际数据往往很难假设出这种参数模型的分布.为此,提出一种二类切比雪夫正交多项式的非参数图像混合模型分割方法.首先,设计出一种基于二类切比雪夫正交多项式的图像非参数混合模型,每一个模型的平滑参数根据误差方法和最小的准则进行计算.然后,利用随机期望最大(SEM)算法求解正交多项式系数和每一个模型的权重.此方法不需要对模型作任何假设,可以有效克服有参混合模型与实际数据分布不一致的问题.实验表明,该方法比高斯混合模型分割效率更高,并比其他非参数正交多项式混合模型有更好的分割效果.     

基于抽样的正交多项式混合模型图像分割

针对有限混合模型中参数估计方法对先验假设存在过分依赖和图像数据量大的问题,提出了一种基于抽样的非参数余弦正交序列的图像混合模型分割方法.首先,基于图像的直方图进行分层随机抽样得到样本数据,根据样本数据构建非参数正交多项式混合模型,对于模型的平滑参数采用最小均方差方法进行估计;其次,采用NEM(Nonparametric Expectation Maximum)算法求解混合模型中正交多项式系数和模型的混合比;最后,根据贝叶斯准则进行图像分割.此方法能够克服参数模型的基本假设与实际的物理模型之间存在的差异,实验表明该方法比GMM和Hermite混合模型分割方法分割质量高,而且分割速度快.     

多元Chebyshev正交多项式混合模型及其在医学图像分割中的应用

针对原有一元正交多项式混合模型只能根据灰度特征分割图像的问题,提出一种基于多元Chebyshev正交 多项式混合模型的多维特征的医学图像分割方法。首先,根据Fouricr分析方法与张量积理论推导出图像的多元 Chcbyshcv正交多项式,并构建多元正交多项式的非参数混合模型,用最小均方差(MISE)估计每一个模型的平滑参 数;然后,用EM算法求解正交多项式系数和模型的混合比。此方法不需要对模型作任何假设,可以有效克服“模型失 配”问题。通过实验,表明了该分割方法的有效性。     

基于多分辨率的非参数正交多项式医学图像融合方法

基于估计理论的图像融合方法都是假设图像偏移或噪声服从高斯混合分布,容易造成模型不匹配和丢失局部细节等问题。文中提出一种基于小波的多分辨率的非参数正交多项式医学图像融合方法。首先,对图像进行多分辨率分解。对低频部分,根据图像信息模型和非参数正交多项式混合模型,采用非参数期望最大法估计模型参数,获得低频融合结果。对高频部分,采用系数绝对值选大法进行融合。然后,将高频和低频部分结果进行反变换,得到最终融合图像。实验结果表明,该方法融合质量优于其它方法,融合时间大为缩短。     

基于邻域信息的B样条密度模型的医学图像分割研究

针对有参混合模型的聚类算法需要假设模型为某种已知的参数模型而存在模型不匹配及应用于图像分割时对噪声比较敏感的问题,提出了一种基于空间邻域信息的B样条密度模型的图像分割方法。首先,通过构建基于规范化的B样条密度函数的非参数混合模型,定义空间信息函数,使得分割模型具有空间邻域信息;其次,利用非参数B样条期望最大(NNBEM)算法估计密度模型的未知参数;最后根据贝叶斯准则实现图像的分割。该图像分割方法不需要假设图像符合某种模型,就可以克服实际数据分布与假设图像模型不一致的问题。此方法有效克服了"模型失配"问题,而且有力抑制了噪声点,同时很好地保留了边界的特性。分别对模拟图像进行仿真,验证了基于空间邻域信息的B样条密度模型的分割方法的有效性。     

基于改进高斯混合模型的MR图像分割

传统高斯混合模型分割核磁共振图像时严重依赖初值,且易受图像中偏移场与噪声的影响。为此,提出一种基于片信息的改进高斯混合模型。采用模糊C均值聚类方法优化初始值,以减小初值对分割结果的影响,加快算法的收敛速度。使用Legendre多项式对偏移场进行拟合,并融入EM框架中,得到光滑的偏移场。利用邻域信息降低噪声的影响,使模型在降低噪声影响的同时,保留细长拓扑结构信息。实验结果表明,该模型能恢复出偏移场,分割结果较好。     

基于EM算法的混合模型医学图像分割

医学图像分割中的期望最大化(EM)算法在求解混合模型参数时存在局限性。为此,提出一种模糊约束的混合模型图像分割算法。该算法以像素的独立性假设为前提,在采用EM算法对模型参数进行求解的过程中,通过模糊集合论方法,引入像素空间信息。实验结果表明,该算法没有引入新的模型参数,能够保持独立混合模型的简单性,且具有自动模型选择能力,可以获得较理想的分割结果。     

基于超像素及贝叶斯合并的图像分割算法

针对超像素分割算法中普遍存在的过分割问题,结合Mean Shift算法和非参数贝叶斯聚类模型,提出了一种新的图像分割算法MS-BRM（Mean Shift based Bayesian Region Merging）。首先,利用Mean Shift算法对图像进行超像素分割,然后根据非参数贝叶斯聚类模型,融合超像素的空间信息,提出一种区域合并策略对超像素进行合并,得到了最终的分割结果。实验结果表明,MS-BRM算法改善了超像素的过分割问题,对图像进行分割的结果保留了图像的边界信息,更加符合人类视觉的判断结果。     

基于可变形状参数Gamma混合模型的区域化模糊聚类SAR图像分割

为了解决传统模糊聚类算法无法准确刻画SAR图像强度分布特征以及抗噪性差等问题,提出一种基于可变形状参数Gamma混合模型(GaMM)的区域化模糊聚类SAR图像分割方法.首先,利用Voronoi划分技术将SAR图像完备地划分为若干个Voronoi多边形;然后,假设SAR图像强度服从可变形状参数的GaMM,以GaMM的负对数函数刻画多边形与聚类间的非相似性关系,并结合具有邻域多边形空间约束作用的规则化项定义区域化模糊聚类目标函数;在模型参数求解的过程中,对于无法直接通过导数求解的形状参数及生成点集,设计以目标函数最小化为准则的移动更新操作以逐步逼近最优解.通过对真实及模拟SAR图像分割结果进行定性定量分析,有效地验证了所提出算法对SAR图像强度分布拟合的准确性及分割的抗噪性.     

一类离散模糊系统的迭代学习控制算法

针对离散T-S模糊系统的终端控制问题,提出了一种基于离散Legendre正交多项式的迭代学习算法。该算法把待求控制量表示为离散Legendre正交多项式的线性组合,将求控制量问题转化为求离散Legendre正交多项式系数问题。在此基础上,用迭代学习的方式来修正控制量的离散Legendre系数,并运用不确定离散系统的H∞设计方法求解学习增益矩阵。最后以机器人为例进行仿真,仿真结果表明了所提算法能实现工业机器人的精确定位。     

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.     

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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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