基于支持向量机的遥感图像分类方法

为了提高遥感图像分类的精度,弥补传统最大似然分类方法所固有的分类时样本不足的缺陷,提出了一种基于支持向量机、光谱特征和纹理特征相结合的遥感图像分类方法。采用ETM数据,按照其所提方法进行了具体分类实验,并将实验结果与最大似然法分类的结果进行了比较分析。结果表明,利用基于支持向量机的方法进行遥感图像分类,精度明显优于最大似然法分类的精度。利用光谱特征与纹理特征相结合进行分类比单纯运用光谱特征进行分类效果要好。     

一种矩阵分块的GNSS相位模糊度快速解算方法

为解决GNSS模糊度解算中最小二乘模糊度去相关（least-square ambiguity decorrelation adjustment,LAMBDA）算法涉及大量矩阵运算、降相关耗时较长等问题,提出一种对条件方差矩阵进行分块的最小二乘模糊度去相关（blocking in least-square ambiguity decorrelation adjustment,BLAMBDA）算法。该算法对条件方差矩阵进行分块,减少条件方差排序次数,并在此基础上对Cholesky分解公式进行整合,减少Cholesky分解过程中的数乘运算。仿真实验和实测结果表明,与LAMBDA算法相比,BLAMBDA算法的整体解算效率提升显著,且更加稳定。     

基于改进层次分析法的雷电防护能力模糊综合评价

为科学评价雷电防护措施的防护能力,分析国内外多种评价方法的优劣,结合雷电防护措施的特点提出基于改进层次分析法的模糊综合评价。依据雷电防护相关技术标准和规范,综合考虑雷电环境、承载体特征、自然因素的影响,建立雷电防护能力评价指标体系。利用改进层次分析法计算各级指标的权重,采用模糊综合评价法确定雷电防护能力评价等级。运用此方法对采取多种雷电防护措施的油气集输站进行雷电防护能力评价,评价等级与实际情况和有关文献案例相符,表明该方法适用于雷电防护能力的评价。     

仿射秩最小化问题的一种解法

低秩矩阵恢复问题在众多领域有重要应用.由于秩函数的复杂性,通常寻求其替代函数进而求解松弛问题.核范数是普遍使用的替代函数之一,但其恢复能力有限.本文提出了一种新的松弛模型用于求解低秩矩阵恢复问题,并给出了邻近梯度下降算法,证明了算法的收敛性.实验数据表明模型的恢复能力远高于核范数模型.算法对于含噪声的情形同样适用,与核...     

Attribute trajectory analysis: a framework to analyse attribute changes using trajectory analysis techniques

Trajectory analysis has attracted growing attention in the research field of geography. Beyond traditional moving object trajectories, another type of trajectory exists in which the coordinates are object attributes rather than geographical coordinates. In this paper, a framework to analyse these so-called attribute trajectories is proposed that uses four techniques typically employed in the analysis of moving object trajectories: the Reeb graph, the similarity matrix, the convoy and the mega-convoy. The Reeb graph provides the ability to visualise the temporal dynamics of attribute similarities. The similarity matrix is a supplement of the Reeb graph whose purpose is to visualise the pairwise similarities among the attributes. Moreover, the similarity matrix forms a basis for clustering. The convoy highlights objects whose attributes remain similar for a sufficiently long period. The mega-convoy reduces the number of convoys and reveals their evolutionary histories by merging overlapping convoys. A small real-world meteorological dataset is used as an example to illustrate the attribute trajectory analysis framework and the techniques. This paper aims to form a starting point for applying trajectory analysis techniques in many research fields.     

Fe同位素的MC-ICP-MS测试方法

过渡族元素同位素研究是新兴的研究领域和国际研究前沿, 是同位素地球化学研究的热点。本研究利用Neptune型多接收等离子质谱(MC-ICP-MS), 采用标准-样品-标准交叉校正和以Cu为内标的方法对仪器的质量歧视进行校正, 对浓度效应、基质效应、干扰元素扣除和测试的长期重现性进行了检验, 建立了高精度的Fe同位素测试技术。这两种校正方法对实验室标准HSP I Fe在一段时间内δ56Fe和δ57Fe的测试结果分别为0.08‰(2SD)和0.14‰(2SD)分析精度达到国际同类实验室水平, 测试结果在误差范围内与文献值完全一致。     

新型常压热解离化学电离装置的研制及应用

为了克服常压热解离化学电离装置(TDCI)热源控制不稳定、背景干扰较大、实验重现性相对较差等问题。文章在前期研究的基础上,分别对仪器各组成部件进行优化和改进,研制出能够根据待测物的热稳定性、极性、挥发性、熔点等性质,能够对仪器的温度、加热时间、加速电压等仪器参数连续、精确可调的新型常压热解电离源实验装置,并进行了优化和表征。与原研制的TDCI实验装置相比,新型TDCI电离装置的高压调节和温度控制的连续性和精确度以及热源的稳定性得到了极大的提高。高压调节的最小刻度从原来的1 V减小到0.1 V,温度控制系统的调控精确由原来的±5℃减小到±1℃。采用新型TDCI-MS技术,在常压和无需样品预处理的条件下,实现了实际样品可乐中痕量兴奋剂可卡因和牛奶中弱极性物质三聚氰胺的快速检测,单个样品检测时间都小于30 s,检出限低,可卡因和三聚氰胺的最低检出限分别为1.12×10^-12 g/mL和2.62×10^-11 g/mL,重现性好,相对标准偏差(RSD)为4.61%~9.80%,优于原TDCI电离装置的检测结果,完全满足实际样品的检测需要。由于其具有独立稳定的加热装置,与表面解吸常压电离源相比,本仪器装置更适于难挥发性化合物的快速分析。     

Ability to detect and locate gross errors on DEM matching algorithm

Abstract

Digital elevation model (DEM) matching techniques have been extended to DEM deformation detection by substituting a robust estimator for the least squares estimator, in which terrain changes are treated as gross errors. However, all existing methods only emphasise their deformation detecting ability, and neglect another important aspect: only when the gross error can be detected and located, can this system be useful. This paper employs the gross error judgement matrix as a tool to make an in-depth analysis of this problem. The theoretical analyses and experimental results show that observations in the DEM matching algorithm in real applications have the ability to detect and locate gross errors. Therefore, treating the terrain changes as gross errors is theoretically feasible, allowing real DEM deformations to be detected by employing a surface matching technique.