视觉传感网络图像破损数据交互方法仿真

针对传统破损数据交互方法未考虑位置系数导致交互效果差的问题,提出基于双边非局部均值算法的视觉传感网络图像破损数据交互方法.根据采集图像与真实场景之间的关系,构建像素多尺度域模型和多传感器矢量模型,确定传感器噪声特征信息;引入双边非局部均值算法获得位置系数,结合像素及其周围像素点之间的关联性进行去噪处理;按照贝叶斯理论建立破损数据观测模型,计算图像破损区域分布函数的均值和方差;设定扩展结构,定义像素参数,提取图像梯度边缘特征;将归一化互信息作为交互准则,选择两幅图像做空间变换,并使用金字塔分解方法优化交互过程,减少计算量.仿真结果证明,所提交互方法能够达到图像修复、增强图像质量的目的.     

基于混合基稀疏图像表示的压缩传感图像重构

单一基函数不能对同时包含边缘和纹理信息的自然图像进行最优压缩传感图像重构. 本文根据Meyer的卡通--纹理图像模型和生物视觉原理, 用拉普拉斯塔式分解和圆对称轮廓波分别表示图像的光滑成分和边缘成分, 并构造了窄带轮廓波变换实现纹理成分的稀疏表示. 三种稀疏变换的基函数分别与视觉皮层中的侧膝体、简单细胞及栅格细胞的感受野类似. 结合三种图像稀疏表示方法和凸集交替投影算法提出了基于混合基稀疏表示的压缩传感图像重构算法. 实验结果表明,与基于块匹配三维变换迭代收缩的图像重构算法比较, 本文算法能获得更高的图像重构质量.     

基于稀疏分解的图像修复方法

提出将冗余离散小波变换(RDWT)和波原子变换(WAT)作为字典对应用于图像稀疏形态成分分解,获得图像的结构与纹理;然后针对结构和纹理所具有的不同形态学特征,对结构采用具有曲率驱动、边缘强化和平滑去噪性能的CDD模型修复,对纹理采用基于样例的Criminisi纹理合成方法修复;最后合成获得修复结果。实验结果表明,该修复方法能够获得强且光顺的边缘,纹理清晰完整,相比于传统方法具有更好的修复结果。     

小波树结构在贝叶斯压缩感知图像重构中的应用研究

结合贝叶斯和压缩感知理论,提出了一种基于小波变换的图像压缩和重建方法。这种算法充分利用了小波变换系数的结构特征和相关性,有效地提高了图像的压缩比例和重建精度。对小波变换的尺度系数采用基于预测的恢复算法;对高频系数的恢复结合了贝叶斯理论和压缩感知理论,采用了一种基于回归模型的方法,通过高斯混合参数对未知权值参数赋予确定的先验分布,以限制系数的稀疏性。该方法能够得到未知参数的一组具有较高概率的模型,从而实现系数在MMSE意义下的重建。与现有的图像压缩方法以及其它基于压缩感知的图像压缩方法相比,该算法能够获得较高的图像重建质量和较大的图像压缩比。     

基于稀疏重构框架下剪切波的SAR图像去噪

SAR图像很容易被乘性噪声多污染,进而影响SAR图像后序的分析与处理。本文中提出了一种基于剪切波稀疏编码的SAR图像移除乘性噪声的新模型。首先通过压缩感知理论建立SAR图像去噪模型;其次通过剪切波变换获得剪切波系数,每个尺度的系数视为一个单元;对于每个单元,通过剪切波域的贝叶斯估计对稀疏系数进行迭代估计。重现的单元最后结合起来构造去噪后的图像。SAR图像去噪效果显示了该算法有良好的表现性,对噪声具有鲁棒性;本文提出的算法不仅有较好的去噪效果,而且还保存了更多的边界信息。     

MCA分解的唐墓室壁画修复算法

壁画数字化修复工作极大降低了手工修复时带来的不可逆的风险。根据唐墓室壁画人工修复时先整体结构、后局部纹理的思路,提出一种基于形态学成分分析(morphological component analysis,MCA)分解的唐墓室壁画修复算法。首先结合唐墓室壁画的特点,采用改进的MCA方法进行图像分解,得到结构部分和纹理部分;然后根据图像分解后纹理和结构的复杂程度与稀疏程度,分别采用简化的全变分(total variation,TV)算法和K奇异值分解(K-singular value decomposition,K-SVD)算法进行修复。实验结果表明,该算法可兼顾纹理与结构的修复效果,唐墓室壁画中的裂缝现象的破损修复精度得到提高。     

基于形态成分分析和Contourlet变换的自适应阈值图像去噪方法

针对含有丰富纹理和边缘特征的噪声图像,提出一种基于形态成分分析(MCA)和Contourlet变换的自适应阈值图像去噪方法.该方法首先引入MCA将噪声图像分为低频部分和高频部分,在此基础上设计一种自适应的分层阈值估计处理策略.根据噪声的分布特性,通过阈值估计和Contourlet变换对噪声图像的低频部分和高频部分进行分频带去噪处理,有效去除噪声图像中的噪声.通过对噪声图像的仿真实验表明,文中方法能较好地保留图像纹理和边缘,并且去噪效果优于传统的均值滤波去噪、中值滤波去噪、小波多层阈值去噪和轮廓波多层阈值去噪方法.     

图像的多成分混合字典压缩感知表示及重构

信号分解的稀疏程度决定了压缩感知重构信号的精度,针对标准正交基稀疏程度的不足,提出了基于混合字典的压缩感知图像分解和重构方法。构建匹配图像边缘和纹理的二维Gabor字典,将图像在离散余弦字典与建立的二维Gabor字典上进行混合稀疏分解,得到图像的光滑成分、边缘成分和纹理成分。对得到的稀疏成分进行CS观测,通过求解一个优化问题重构图像。实验结果表明,构造的混合字典能够对图像进行更加稀疏的表示,在相同的采样率下,图像的重构质量优于标准正交基分解。     

小波变换估计非线性扩散最优停止时间

Gilboa提出一种针对高斯噪声的基于信噪比(SNR)最优的迭代停止时间估计方法。该方法用一个噪声补丁来估计图像噪声与冗余(噪声图像与去噪图像的差)的协方差对冗余方差的导数,补丁是随机生成的纯高斯噪声图像,其均值为零并且方差等于噪声图像的噪声方差。在实际应用中图像噪声方差未知,补丁的噪声是随机的,不同噪声所得到的最后停止时间可能不同。针对这些问题,对该方法进行了改进。首先将图像进行小波变换;再利用小波系数的层间相关性去掉第1层斜向高频系数(HH1)中的边缘纹理信息,获得"纯"的子噪声;然后把子噪声作为补丁的噪声取代随机噪声。实验结果表明,改进方法不仅能解决随机噪声补丁的两个问题,而且去噪图像在峰值信噪比(PSNR)上有一定优势。     

结合压缩感知与非局部信息的图像超分辨率重建

针对现有的超分辨率重建算法只考虑图像块的灰度信息,而忽略了纹理信息,并且大多数非局部方法在强调非局部信息的同时,没有考虑局部信息的问题,提出一种结合压缩感知与非局部信息的图像超分辨率重建算法。首先,根据图像块的结构特征计算像素之间的相似性,同时考虑了图像块的灰度信息和纹理信息;然后,合并图像的局部和非局部信息来估计相似像素的权重,构造结合局部和非局部信息的正则项;最后,将图像的非局部信息引入到压缩感知框架中,通过迭代收缩算法求解稀疏表示系数。实验结果表明,所提算法与现有的基于学习的超分辨率算法相比,重建图像的峰值信噪比和结构相似度取值更高,并且在恢复图像纹理细节的同时有效抑制了噪声。     

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。     

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.     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

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.