正规矩阵选取半参数灰色模型改进的预测建模

正规矩阵是对模型误差补偿性的直接表达,时间序列法用一阶差分方程和二阶差分方程计算得到不同的正规矩阵。针对传统GM(1,1)模型没有考虑模型误差,而数据处理过程中所建立的数学模型与客观现实并不一致的问题,该文提出建立顾及模型误差的半参数模型的GM(1,1)模型。对由传统半参数模型得到的正规矩阵采取一阶差分法进行改进,并通过算例证实了改进正规矩阵的半参数模型的GM(1,1)预测精度更高。     

Quaternion-EKF的多源传感器联合定向算法

针对磁力计易受干扰和陀螺仪易漂移的问题,使用扩展卡尔曼滤波EKF(Extended Kalman Filter)融合多源传感器进行定向。利用基于四元数的EKF,在当地磁场和重力加速度的基础上融合加速度计、陀螺仪和磁力计观测信息,并通过自适应算法构建过程噪声向量和观测噪声向量的协方差矩阵以解决载体运动和周围磁场干扰对重力和地磁场观测值的影响。实验结果表明,该算法可以有效地减弱陀螺仪漂移和磁场对定向的干扰,获得更加精确和稳定的航向角信息。     

Estimating Population Attribute Values in a Table: “Get Me Started in” Iterative Proportional Fitting

Iterative proportional fitting (IPF) is a technique that can be used to adjust a distribution reported in one data set by totals reported in others. IPF is used to revise tables of data where the information is incomplete, inaccurate, outdated, or a sample. Although widely applied, the IPF methodology is rarely presented in a way that is accessible to nonexpert users. This article fills that gap through discussion of how to operationalize the method and argues that IPF is an accessible and transparent tool that can be applied to a range of data situations in population geography and demography. It offers three case study examples where IPF has been applied to geographical data problems; the data and algorithms are made available to users as supplementary material.     

基于通径分析的酒金盆地绿洲化时空变化及影响因子研究

基于Landsat遥感影像和社会经济数据等,重建1963~2009年间西北干旱区酒泉金塔盆地(酒金盆地)绿洲空间分布图,采用转移矩阵、绿洲动态度和通径分析法等开展酒金盆地绿洲时空变化过程的区域差异和影响因子差异研究。结果表明：近50 a来,酒金盆地绿洲面积呈现增加趋势,表现为酒泉绿洲连续增长和金塔绿洲的波动式增长。酒泉绿洲扩张主要表现为绿洲边缘区的外延扩张,金塔绿洲主要表现为绿洲边缘区和季节性河道两侧绿洲波动变化。酒泉绿洲稳定性较金塔绿洲的高,水资源的持续供给与否决定着绿洲边缘稳定的关键,尤其在金塔绿洲。人类活动的区域差异和政策响应程度及经济水平的差异是造成2个绿洲时空变化差异的内在影响因子。     

A stream ordering approach based on network analysis operations

Stream ordering is a technique for characterizing the constituent parts of a drainage network. Network analysis remains one of the most popular and persistent research and application areas in geographic information science. In this study, a new stream ordering approach based on geographic information systems tools and network analysis operations is proposed. The new method combines the concepts of modern network analysis operations, which mainly deal with derivations of the best route solution, and the previous stream ordering techniques. In this context, the method readily identifies the channel heads hierarchically in order to derive main stream channel and its tributaries, and assigns a unique order for each stream on the network.     

一种基于无人机位姿信息的航拍图像拼接方法

针对现有航拍图像拼接方法处理速度较慢的问题,提出一种基于无人机位姿信息的快速拼接方法。首先从机载GPS和惯性导航单元获得无人机航拍时的坐标和姿态角,根据每一幅航拍图像对应的无人机坐标和姿态角计算它们之间的单应变换矩阵,实现航拍图像之间的快速配准。然后通过单应变换矩阵的运算得到拼接图像之间的配准,最后完成多幅图像的拼接得到整个区域的全景图。试验结果证明该方法快速有效。     

群组目标空间方向关系形式化描述模型

针对目前群组目标空间方向关系模型在描述方向关系方面存在的不精确及复杂性等问题,该文提出一种形式化描述模型。该模型采用"剥皮"法计算得到源目标群的边界多边形,较好地顾及了空间形状及分布范围对方向关系的影响;并通过方向关系矩阵模型计算源目标群的边界多边形与各方向区域之间的交,借助矩阵形式化描述源目标群相对于参考目标群的空间方向关系。实验结果表明,该模型较好地克服了现有方法中存在的缺陷,能够准确判断地理空间中两个群组目标之间的空间方向关系。     

Relation Matrix of Water Exchange for Sea Bays and Its Application

1 .IntroductionWater exchange of sea bays is a basic issue for marine environment study. Water exchange be-tween a coastal area andthe outside area dueto advection and diffusionis animportant waytoimprovethe water qualityinthe coastal area . Withthe rapid…     

An identification of wave propagation based on a single-point measurement

This study presents the identification of wave propagation using the information measured at a fixed point. The mathematical model used to carry out this research is an integral equation. The equation turned out to be a Fredholm integral equation of the first kind. The discretized matrix equation yielded an ill-conditioned system. To secure the stability of the system, Tikhonov regularization was applied to the ill-conditioned system. The analysis of the numerical computation proved that the regularization was able to retain the target spectrum.     

平均场分解初探

本文探讨了经验正交分解的基本原理,对两种平均场分解方法进行了比较,结果表明,利用距平场分解得到的特征向量作为基底分解平均场是可行的,文中给出的实例清楚地显示出几个主要影响因子的分布特征。 文中还讨论了几个与经验正交分解法的有效性有关的理论问题,并定义了两种关系矩阵,通过分析它们之间的关系,间接地导出了时空转换公式。