Endmember variability in Spectral Mixture Analysis: A review

The composite nature of remotely sensed spectral information often masks diagnostic spectral features and hampers the detailed identification and mapping of targeted constituents of the earth's surface. Spectral Mixture Analysis (SMA) is a well established and effective technique to address this mixture problem. SMA models a mixed spectrum as a linear or nonlinear combination of its constituent spectral components or spectral endmembers weighted by their subpixel fractional cover. By model inversion SMA provides subpixel endmember fractions. The lack of ability to account for temporal and spatial variability between and among endmembers has been acknowledged as a major shortcoming of conventional SMA approaches using a linear mixture model with fixed endmembers. Over the past decades numerous efforts have been made to circumvent this issue. This review paper summarizes the available methods and results of endmember variability reduction in SMA. Five basic principles to mitigate endmember variability are identified: (i) the use of multiple endmembers for each component in an iterative mixture analysis cycle, (ii) the selection of a subset of stable spectral features, (iii) the spectral weighting of bands, (iv) spectral signal transformations and (v) the use of radiative transfer models in a mixture analysis. We draw attention to the high complementarities between the different techniques and suggest that an integrated approach is necessary to effectively address endmember variability issues in SMA.     

浅谈网页制作的经验与技巧

在制作网页的过程中,会发现预想的结果和实际预览网页时的效果有很大的区别,比如说网页在不同分别率预览时发生了改变、网页中的字体大小也在变化、图片上传后不能显示等等。在几年的网页教学中,笔者不断摸索,总结了一些经验和技巧供大家借鉴。     

基于DWT域的图像数字水印算法

提出了一种基于DWT域的图像数字水印算法。通过对宿主图像、经过Amold变换加密后的水印图像分别进行多分辨率小波分解,达到自适应嵌入水印信息的目的。实验结果表明,该方法嵌入的数字水印不但具有较好的不可见性,而且对图像处理有较好的鲁棒性。     

Solving a bi-criteria permutation flow-shop problem using shuffled frog-leaping algorithm

Flow shop problems as a typical manufacturing challenge have gained wide attention in academic fields. In this paper, we consider a bi-criteria permutation flow shop scheduling problem, where the weighted mean completion time and the weighted mean tardiness are to be minimized simultaneously. Due to the complexity of the problem, it is very difficult to obtain optimum solution for this kind of problems by means of traditional approaches. Therefore, a new multi-objective shuffled frog-leaping algorithm (MOSFLA) is introduced for the first time to search locally Pareto-optimal frontier for the given problem. To prove the efficiency of the proposed algorithm, various test problems are solved and the reliability of the proposed algorithm, based on some comparison metrics, is compared with three distinguished multi-objective genetic algorithms, i.e. PS-NC GA, NSGA-II, and SPEA-II. The computational results show that the proposed MOSFLA performs better than the above genetic algorithms, especially for the large-sized problems.     

Spatial interest pixels (SIPs): useful low-level features of visual media data

Visual media data such as an image is the raw data representation for many important applications. Reducing the dimensionality of raw visual media data is desirable since high dimensionality degrades not only the effectiveness but also the efficiency of visual recognition algorithms. We present a comparative study on spatial interest pixels (SIPs), including eight-way (a novel SIP detector), Harris, and Lucas‐Kanade, whose extraction is considered as an important step in reducing the dimensionality of visual media data. With extensive case studies, we have shown the usefulness of SIPs as low-level features of visual media data. A class-preserving dimension reduction algorithm (using GSVD) is applied to further reduce the dimension of feature vectors based on SIPs. The experiments showed its superiority over PCA.

基于混沌的彩色图像加密算法研究

利用混沌信号的优良特性,结合彩色位级图像的内在特点,提出了一种新的彩色图像混沌加密算法。首先将彩色图像的RGB三基色分别划分为8幅位级图像并将其作为一个整体,利用超混沌系统生成混沌序列,进行位级图像置乱,然后利用Logistic混沌序列进行图像像素扩散,最后进行仿真测试和性能分析,结果表明所提算法具有较强的安全性和有效性。     

对七星彩开奖号码的随机性卡方检验

以我国连续200期七星彩开奖号码为样本,采用卡方检验法检验每个字符出现的概率是否相同,并检验同一期开奖号码中字符重复出现的次数是否在可接受的范围之内。统计检验表明：我国七星彩的开奖号码具有较好的随机性。     

具有排列扫描特征的多态蠕虫传播模型

多数蠕虫传播模型都是基于简单的随机扫描,蠕虫形态相对固定。为此,研究排列扫描技术,结合自然生物的取食繁殖规则,提出一种多态蠕虫动态传播的数学模型。通过一系列相互独立的方程表现蠕虫的整体行为,计算传播过程中各类被感染蠕虫的数目。仿真实验结果表明,该模型能准确描述多态蠕虫的传播过程。     

求置换因子循环矩阵的极小多项式和逆的算法

本文引入了任意域上置换因子循环矩阵,利用多项式环的理想的Gr(?)bner基的算法给出了任意域上置换因子循环矩阵的极小多项式和公共极小多项式的算法,同时给出了这类矩阵逆矩阵的两种算法最后,利用Schur补给出了任意域上具有置换因子循环矩阵块的分块矩阵逆的一个算法,在有理数域或模素数剩余类域上,这一算法可由代数系统软件CoCoA4．0实现。