A holistic approach to aligning geospatial data with multidimensional similarity measuring

Semantically aligning the heterogeneous geospatial datasets (GDs) produced by different organizations demands efficient similarity matching methods. However, the strategies employed to align the schema (concept and property) and instances are usually not reusable, and the effects of unbalanced information tend to be neglected in GD alignment. To solve this problem, a holistic approach is presented in this paper to integrally align the geospatial entities (concepts, properties and instances) simultaneously. Spatial, lexical, structural and extensional similarity metrics are designed and automatically aggregated by means of approval voting. The presented approach is validated with real geographical semantic webs, Geonames and OpenStreetMap. Compared with the well-known extensional-based aligning system, the presented approach not only considers more information involved in GD alignment, but also avoids the artificial parameter setting in metric aggregation. It reduces the dependency on specific information, and makes the alignment more robust under the unbalanced distribution of various information.     

结合NASA DEM和AW3D30 DEM的太原市DEM数据融合

本文首先以DEM数据为例,将输入数据与参考数据配准至同一像素位置,然后分别将均方根误差和标准差作为参考指标,在不同坡度等级的区域内,通过权重系数从0至1的遍历探寻最佳加权融合系数,从而确定融合方案并进行NASA DEM与AW3D30 DEM的数据融合,最后对融合效果进行定量评价。结果表明:配准前,NASA DEM沿x、y、z方向的位移分别为-2.65、2.41、0.60m,AW3D30 DEM位移分别为1.04、7.51、-3.33m;配准后,原始数据各项误差均减小,且NASA DEM的系统误差基本消失。融合DEM相较于NASA DEM,平均误差和均方根误差分别减小了25.0%和36.8%;对于AW3D30 DEM,误差降幅分别为86.5%和13.2%。     

黄茅海内治导线对潮汐要素影响的试验研究

通过物理模型试验 ,研究了黄茅海内不同治导线对潮汐要素的影响 ,得出治导线对河口湾内的潮位变化随着上游径流量的增加而逐渐减弱的结论。中水大潮时 ,湾顶与湾腰处高潮位降低 ,低潮位抬高 ,其幅度与治导线进占的海域面积成正比。洪水大潮时 ,高潮位一般也降低。低潮位则有时降低 ,有时有所抬高。河口湾治导线实施后 ,涨潮最大流速、平均流速和落潮平均流速均有所减小 ,但落潮最大流速不减反增。涨、落潮潮量有不同程度的减少 ,其减幅与治导线的进占规模成正比。各站的高、低潮位发生时间都有前移趋势 ,治导线越往外推 ,潮时前移量就越大。本文对这些现象的成因进行了分析 ,并就潮位、潮流速及潮流量的变化对防洪水位和交通航运水深的影响作了阐述。     

简化自协方差最小二乘噪声估计的SINS静基座初始对准

目的 研究了观测噪声统计特性未知的情况下,简化的自协方差最小二乘噪声估计方法在捷联惯性导航系统静基座初始对准中的应用。该算法采用迭代计算的策略,同时进行噪声估计和初始姿态修正,估计精度较高。通过数值方法对此算法的正确性和有效性进行了验证。     

流动宽频带地震计自噪声测试研究

分别采用双台地震计自噪声互相关分析法(以下简称“Holcomb双台法”)和3台地震计自噪声互相关分析法(以下简称“Sleeman多台法”)对CMG-3T、BBVS-120、STS-2型流动宽频带地震计进行自噪声测试研究.结果表明:Sleeman多台法因有效地规避了传递函数引起的误差,在处理流动宽频带地震计实际记录数据方面比Holcomb双台法更能有效地滤除背景噪声;在简单测试条件下,3种常用流动地震计的自噪声在0.06 ～1 Hz频带内均低于NLNM曲线,显示了相当好的噪声性能指标;在流动台阵观测过程中,地震计方位准确性以及地震计的保温防护措施是保证发挥仪器性能的重要因素.     

地面检校场POS辅助航空摄影测量检校方法

POS辅助航空摄影测量中会存在视准轴误差和空间位置偏心差,其会对最终结果精度产生较大的影响,传统的飞行检校方法存在耗费大以及对天气、空域等因素的要求高等特点,不方便进行经常性检校工作。本文提出了一种基于地面检校场的检校方法,并详细推导出误差解算数学模型,同时利用建立好的地面检校场设计试验,最后的试验结果证明了该方法的正确性。     

A metaheuristic approach for efficient and effective sketch-to-metric map alignment

Sketching as a natural mode for human communication and creative processes presents opportunities for improving human–computer interaction in geospatial information systems. However, to use a sketch map as user input, it must be localized within the underlying spatial data set of the information system, the base metric map. This can be achieved by a matching process called qualitative map alignment in which qualitative spatial representations of the two input maps are used to establish correspondences between each sketched object and one or more objects in the metric map. The challenge is that, to the best of our knowledge, no method for matching qualitative spatial representations suggested so far is applicable in realistic scenarios due to excessively long runtimes, incorrect algorithm design or the inability to use more than one spatial aspect at a time. We address these challenges with a metaheuristic algorithm which uses novel data structures to match qualitative spatial representations of a pair of maps. We present the design, data structures and performance evaluation of the algorithm using real-world sketch and metric maps as well as on synthetic data. Our algorithm is novel in two main aspects. Firstly, it employs a novel system of matrices known as local compatibility matrices, which facilitate the computation of estimates for the future size of a partial alignment and allow several types of constraints to be used at the same time. Secondly, the heuristic it computes has a higher accuracy than the state-of-the-art heuristic for this task, yet requires less computation. Our algorithm is also a general method for matching labelled graphs, a special case of which is the one involving complete graphs whose edges are labelled with spatial relations. The results of our evaluation demonstrate practical runtime performance and high solution quality.     

短线匹配法预制箱梁线形控制方法

短线匹配法预制箱梁施工工艺正逐渐应用于我国大跨度预应力桥梁建设中,预制阶段的线形控制技术是其中的关键.在阐述短线匹配法预制箱梁施工流程的基础上,针对其施工控制特点,着重研究施工控制网的建立、线形测控点的布设、预制坐标系的建立、预制精度的分析、工程独立坐标与桥梁整体坐标的转换、预制过程中的误差分析与修正等线形控制方法.短线匹配法在南京长江第四大桥中的应用,体现了其在特大桥箱梁预制中的优越性和实用价值.     

输水渠道线路优化与漫游数学家模型

在传统漫游数学家模型的基础上,以线路定性方案、渠段纵坡为决策变量,工程总投资为目标函数,考虑渠段线路状态转移和渠道首末水位约束,提出了阶段函数已知情况下的长距离输水渠道线路优化二维动态规划模型。实例证明该法对长距离输水渠道线路系统的优化比传统线路方法更优越。