基于Legendre正交多项式非参数混合模型的图像分割

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的问题,提出了一种非参数的Legendre正交多项式图像混合模型分割方法。首先,设计了一种基于Legendre正交多项式的图像非参数混合模型,并用最小均方差(MISE)估计每一个模型的平滑参数;其次,利用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。通过图像的分割实验表明,该方法比其他非参数混合模型分割效果更好。     

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.     

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t-混合模型的脑MR图像白质分割

核磁共振成像（MRI）作为临床辅助诊断和研究的重要工具,MR图像分割的准确性直接影响着后续处理的正确性和有效性。在目前的图像分割算法中,基于t-混合模型的图像分割方法因其快速和稳健性而受到重视。该方法的一般过程是先估计混合模型的参数,计算图像中每点的后验概率,然后根据贝叶斯最小错误率准则对图像进行分割。根据MR图像的特点,提出了基于t-混合模型的大脑MR图像白质分割的算法,并取得了较好的实验结果。     

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.     

模式识别.自动分割图像新方法研究*

提出一种采用非参数Dirichlet过程混合模型实现图像自动分割的算法。该方法在图像分割时不需要对分类数进行初始化,具有在分割过程中自动获得图像分类数的特点。模型中使用有控制参数的随机变量来代替聚类数,通过调整参数来指定聚类数的范围。使用该算法对具有高噪声的自然图像和临床磁共振图像进行分割实验,并与其他分割算法进行比较。实验结果显示本算法抗噪声性能强,且可以抑制磁共振图像分割过程中的偏场效应。准确度分析显示,图像分割结果的Dice相似性系数均高于90%,表明提出的新算法具有很高的精确性和鲁棒性。     

引入模糊因子的EM图像分割

基于有限高斯混合模型,在采用EM算法对混合模型参数求解的过程中,引入模糊因子,改善图像分割方法.该方法可以降低其对初选值的依赖和像素点值对混合模型分量间参数的干扰.结果表明,对含有高斯噪声影响的图像有较好的分割结果,目标图像的区域形状保持好、相对位置明确.     

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