基于D-LLE算法的多特征植物叶片图像识别方法

为了提高植物叶片图像识别的准确率,提出一种基于差异性值监督局部线性嵌入（D-LLE）算法的多特征植物叶片图像识别方法。该方法提取叶片的颜色、形状和纹理作为叶片多特征,在加权局部线性嵌入（WLLE）算法中引入样本的差异性值构成差异性值监督LLE算法（D-LLE）对叶片高维特征进行降维,在低维空间采用最近邻分类器实现叶片的识别。该方法所用的叶片多特征比单一特征像素值更能描述叶片图像,同时差异性值能够充分挖掘样本的类别信息。基于实拍的叶片图像数据库的实验结果表明,该方法有效提高了叶片的识别精度。     

基于分布结构约束稀疏表示的图像分类方法

为了解决稀疏表示结构信息缺失的问题,从而更加准确地进行图像分类,本文提出一种新的基于结构约束的稀疏表示的图像分类方法。在对图像进行降采样的前提下,提取方向梯度直方图特征后的训练样本上构建稀疏线性编码模型,通过样本间的分布结构信息约束和?1范数最优化求解测试样本的稀疏系数x,利用稀疏系数均值法进行目标的分类识别。基于COREL图像库进行仿真验证,实验证明,基于结构约束稀疏表示的图像分类方法能够获得很好的识别性能,与非结构约束稀疏表示相比本文方法显著提高了图像分类的准确率。     

基于类别相关近邻子空间的最大似然稀疏表示鲁棒图像识别算法

为了构建一个快速鲁棒的图像识别算法, 提出基于类别相关近邻子空间的最大似然稀疏表示图像识别算法. 考虑到每个测试样本的不同分布特性及训练样本选择的类别代表性原则, 不再将所有训练样本作为稀疏表示的字典, 而是基于距离相近准则选择合适子空间, 从每个类别中选取自适应数量的局部近邻构成新的字典, 在减少训练样本的同时保留了稀疏表示原有的子空间结构. 然后基于最大似然稀疏表示识别方法, 将稀疏表示的保真度表示为余项的最大似然函数, 并将识别问题转化为加权的稀疏优化问题. 在公用人脸与数字识别数据库上的实验证明该算法的合理性, 提高识别速度的同时保证了识别精度和算法的鲁棒性, 特别是对于遮挡与干扰图像具有较好的适应性.     

基于稀疏表示和多特征融合的路面裂缝检测

为了提高在实际复杂背景噪声下对路面裂缝检测的精度,提出了一种基于稀疏表示和多特征融合的路面裂缝检测改进算法。该算法首先以图像子块为单位,提取对裂缝识别有效的统计、纹理和形状特征。然后,分别在各个特征矩阵下利用稀疏表示分类方法实现对裂缝子块的识别,再融合不同特征下的识别结果,设计综合识别分类器进行子块检测。最后,在识别出的裂缝子块上,采用基于视觉显著性的像素级检测方法精确提取裂缝细节。在实际高速公路路面数据库上的实验结果表明,该算法有效地提升了路面裂缝检测的精度,具有良好的鲁棒性。     

基于◢l◣▼2▽-范数重构样本约束的稀疏表示人脸识别方法

稀疏表示分类方法在训练样本空间较大的情况下具有良好的分类效果,但是计算的时间成本较高。针对稀疏表示方法的此问题,考虑构造对重构样本的◢l◣▼2▽-范数进行约束,使得重构样本中各类别分量之间的竞争加强,以起到组稀疏的效果,最后提高分类正确率。由于该方法可以直接得到闭式解,使得求解的计算成本大大减小,并且得到的系数稀疏程度与传统方法类似。在公开的人脸和物体图像数据集上和同类型方法的对比实验结果表明,该方法在复杂的条件下具有优秀的图像识别效果。     

信息准则在信息融合中的应用

在图像识别时,如果样本较小,往往会造成识别结果的不准确.采用信息融合的方法可以改善这一问题.在这一过程中,通过引入信任度系数对信息源的质量作出评价,可以提高图像识别的准确性.提出了一种利用信息准则来确定信息源信任度系数的方法,并以此作为衡量信息源质量的依据.其中着重比较了根据两种不同的信息准则所确定的信任度系数对于识别结果的影响.实验结果表明利用BIC准则确定的信任度系数可以得到更好的图像识别结果,同时也证明了该方法应用在信息融合中的可行性.     

基于块稀疏递推残差分析的稀疏表示遮挡鲁棒识别算法研究

针对如何在未知类别的情况下自动检测出遮挡区域,然后在克服遮挡影响的基础上提高识别算法的鲁棒性问题,提出基于块稀疏递推残差分析的稀疏表示遮挡鲁棒识别算法.该算法首先将待测样本分为上下两部分,并分别用对应块的训练样本进行稀疏表示,找出稀疏度更高的块及对应的稀疏解,并将更稀疏前N个解推广到另一个块中,重构测试样本.然后根据重构测试样本与原测试样本的残差推测遮挡像素.考虑到遮挡区域的连续性,利用形态学操作对推测的遮挡区域进行规则化处理并得到加权矩阵.最后利用加权矩阵对测试样本和训练样本进行整体加权归一化,再利用全局稀疏表示进行最终的分类判决.在AR、Yale B及MNIST上的遮挡仿真实验证明该方法不但可大致确定遮挡区域,还可提高遮挡图像识别的性能.     

基于SVM的室外场景图像的景物识别

关于图像识别优化问题,针对在图像的处理中颜色、纹理等单一特征不能全面描述图像的问题,为了精确识别目标图像,提出一种颜色特征和纹理特征相结合的方法.采用基于RGB空间的颜色直方图和基于多通道Gabor滤波器分别对颜色特征和纹理特征进行提取,并对颜色与纹理特征进行外部归一化得到组合特征,并应用支持向量机法(SVM)对组合特征样本训练分类.实验结果表明,改进方法可以克服用单一特征分析图像的片面性,同时提取了理想的图像结构和光谱特性,可以在图像目标的识别和分类中取得较好的效果.     

越野环境中无人驾驶车的障碍目标识别

针对无人驾驶车环境感知技术,基于D-S证据理论融合多传感器信息,旨在解决障碍物身份识别技术难点。基于CCD和激光传感器建立信息融合系统,并提取每种障碍物的5个特征证据,包括距离对比度特征、平行四边形特征、边缘形状特征、灰度纹理特征和颜色特征。再根据目标类型和环境加权系数选择经验公式,通过模糊插值法求取身份隶属度近似获得各特征对目标的相关系数构造基本概率赋值函数。最后制定Dempster组合规则,融合多传感器特征信息识别障碍身份。试验表明本文方法能够准确有效地获取基本概率赋值函数,D-S证据理论融合方法提高了障碍物身份识别的准确性和鲁棒性。     

基于K-SVD和稀疏表示的数字调制模式识别

为了提高数字信号调制模式识别在低信噪比下的正确率,通过分析基于稀疏表示的模式识别,提出了一种基于K-SVD和稀疏表示的特征提取方法.该方法首先引入主成分分析对样本进行降维,然后利用K-SVD算法构造稀疏字典并构建稀疏线性模型,最后通过e1范数最优化求解测试样本的稀疏系数,根据稀疏系数的分布提取特征值.利用支持向量机分类器进行信号的分类识别,仿真研究证明,新方法提取的特征值具有较好的有效性.     

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。     

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.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.