对称群共轭类的计算

设计出对称群共轭类的算法;给出了对称群S3-S13的共轭分类。     

梧州与“珠三角”三大产业结构梯度性模型分析

近年来,梧州市在承接珠三角产业转移的过程中取得了不错的成绩,同时也面临许多问题。文章通过经济模型对梧州与珠三角产业结构和产业梯度系数进行分析比较,得出相关结论,对梧州市承接珠三角产业转移具有借鉴意义。     

梧州与“珠三角”三大产业结构梯度性模型分析

近年来,梧州市在承接＂珠三角＂产业转移的过程中取得了不错的成绩,同时也面临许多问题。文章通过经济模型对梧州与＂珠三角＂产业结构和产业梯度系数进行分析比较,得出相关结论,对梧州市承接珠三角产业转移具有借鉴意义。     

山东半岛海岸带区域土地利用变化空间格局特征

以Landsat TM/ETM+影像为主要信息源解译山东半岛2000年和2005年的土地利用数据,应用转移矩阵、动态度、土地利用程度综合指数等方法,对距离海岸线0～100km范围的土地利用分布与变化特征进行分析.表明:海岸带耕地、草地、农村居民点和林地分布广泛;5年间城市、农村、交通工矿和水体的增加比较显著,而耕地、草...     

多元函数的梯度与方向导数关系的几何表示

首先讨论三元函数的梯度与方向导数关系的几何表示方法。然后将这方法推广到n元可微函数的梯度与方向导数关系的几何表示方法。     

基于视频分析的行人检测

由于存储时间和空间的限制,现有的行人检测算法无法满足智能视频监控的实时性。针对该不足,提出了一种基于视频运动分析的方法。该方法只对图像中含有运动信息的物体进行梯度直方图特征提取和分析,避免了对整帧图像进行窗口式的扫描,又省去了对图像进行金字塔变换的处理,极大的提高了图像处理的效率。与常规行人检测方法进行了对比,实验表明该方法是快速和高效的,能够满足智能视频监控的实时性需要。     

激发极化法在寻找金矿中的应用

某地经由前期地质人员通过大量实地查勘与槽探工作,大致查明了区内基本地质特征、金矿点分布和矿体的规模、产状、形态,初步查明了矿石的结构构造、物质成份等。但要开展生产活动,仍需进一步对矿区内不同岩性及矿层的物性差异进行测试分析;寻找和圈定硫化物富集体及成矿有利带,推断其金矿(化)体分布范围、规模及赋存状态。利用激发极化法对矿区进行中梯扫面及测深工作,更好地为地表工程揭露和深部工程验证提供了依据。     

双边滤波下局部强度与梯度融合的小目标检测

针对红外小目标在复杂背景下难以检测的问题，提出了一种利用局部强度和梯度融合来增强目标抑制背景杂波的算法。首先通过双边滤波技术得到去噪图像，然后利用目标区域与局部邻域的强度差异和梯度向量获得融合图像，最后采用自适应阈值分隔技术成功检测出小目标。理论分析和实验评估结果表明，该算法能够很好地抑制高斯噪声和背景边缘，相比于传统的检测算法，其检测性能显著提高，鲁棒性能较好。     

Parental income and child health in Japan

Previous studies have consistently found evidence of an income gradient in health among children in various countries, and studies in Anglo-Saxon countries have found that this gradient increases with child age. Using nationally representative individual-level data, I examine the association between child health and parental income in Japan. Japan has a child poverty rate that is similar to the rate of many countries that have been studied previously, but Japan outperforms those countries on most health indicators. I find that an income gradient exists in child health in Japan, but that it is limited to specific health measures and symptoms, and that it is weaker overall in that respect than the gradient found in other countries or among Japanese adults. Moreover, I find no evidence that the gradient increases with child age. The fact that children in low-income families have relatively modest and non-accumulating health disadvantages may contribute to the overall health of the Japanese population. Nevertheless, there is a statistically significant negative association between parental income and the incidences of asthma, hearing problems, and dental symptoms in children, implying that future efforts to improve the health of underprivileged children should focus on the prevention and control of these diseases.     

Online Principal Component Analysis in High Dimension: Which Algorithm to Choose?

Principal component analysis (PCA) is a method of choice for dimension reduction. In the current context of data explosion, online techniques that do not require storing all data in memory are indispensable to perform the PCA of streaming data and/or massive data. Despite the wide availability of recursive algorithms that can efficiently update the PCA when new data are observed, the literature offers little guidance on how to select a suitable algorithm for a given application. This paper reviews the main approaches to online PCA, namely, perturbation techniques, incremental methods and stochastic optimisation, and compares the most widely employed techniques in terms statistical accuracy, computation time and memory requirements using artificial and real data. Extensions of online PCA to missing data and to functional data are detailed. All studied algorithms are available in the  package onlinePCA on CRAN.