基于线段的基本线/线拓扑关系计算

空间拓扑关系是空间数据建模、空间查询、分析、推理、制图综合、数据质量控制、数据更新等的基础。目前空间拓扑关系研究的主要成果仍然集中在拓扑关系的描述方面,在计算方面的阐述都非常薄弱,不足以指导系统开发人员编程实现。本文研究了IR2中两个简单线目标间拓扑关系的计算方法,重点分析了线/线拓扑关系计算的特点,提出了一种基于线段的线/线拓扑关系计算方法,并用VC＋＋采用底层开发模式实现了基本线/线拓扑关系的计算。     

改进的Hough变换在机场跑道检测中的应用

提出了一种改进的Hough变换方法用于机场跑道的检测。传统Hough变换存在计算量大等缺陷,本文利用直线边缘的梯度相位信息把Hough变换中θ的取值限定在一个较小的范围内,同时减少用于计算的像素点数,大大降低了计算量。通过实验证明了本文方法切实可行。     

海洋磁力测量中测线方向的选择方法

采用测线间磁异常插值精度分析了测线方向对磁测的影响;探讨了测线方向的选择方法,结合我国不同海区磁异常分布特征给出了不同海区测量时测线方向的选择详细方案。结论表明:海洋磁力测量中,测线方向对磁异常插值精度的影响不大,但是为了获得更高的磁异常插值精度,测线方向应尽量沿磁异常梯度方向布设。给出的测线方向的选择方法和我国不同海区测线方向选择详细方案可供作业人员参考。     

基于特征的海洋锋线过程时空数据模型分析与应用

客观世界存在时空场,大部分地理实体或现象在时空域具有动态变化特性,其空间、时间和属性是过程的统一体,传统的GIS时空数据模型在描述、表达、组织与分析这类数据时面临许多挑战。然而,基于特征的数据模型和以过程为对象的时空数据组织在动态数据的描述与表达的方面具有独特的优势。本文探讨了基于特征的线过程时空数据模型组织的六元组框架体系,实现空间、时间和属性的一体化存储和地理实体的动态分析。在分析线时空过程特性的基础上,归纳总结出3大类12个类别的线过程,进一步提出了基于特征的线过程时空数据模型(Feature-based Line Process Spatio-temporal Data Model)的概念;利用文件层次分块结构对时空线过程数据进行了组织与存储。最后以海洋锋为实例,探讨了该模型在时空数据组织、时空查询、时空过程提取和时空过程可视化等方面的应用。结果表明,该模型能够很好地应用于具有时空过程特性的线数据中,也为时空数据模型的总体设计提供借鉴。     

0605号台风"格美"在江西致灾的气象成因分析

运用常规观测资料、T213资料等,对0605号台风“格美”的移动路径和暴雨成因进行了分析。分析结果表明,“格美”登陆后虽然强度迅速减弱,但由于其减弱后的低气压环流在江西逗留时间长,所携带的水汽和造成的辐合上升条件足以造成江西出现暴雨天气。通过分析探空、地面加密自动站和闪电定位等资料进一步指出,地面中尺度辐合线、对流不稳定和地形抬升的共同作用,加剧了赣西南局地降雨的强度。由于前期台风“碧利斯”已造成赣州市出现较强降水,赣南土壤含水量、地下水位和江河湖库水位均较高,使得“格美”造成的短时强降雨迅速产生有效径流和汇流,导致局地山洪暴发而致灾。     

Climatology of Shear Line and Related Rainstorm over the Southern Yangtze River Valley Based on an Improved Intelligent Identification Method

Based on four reanalysis datasets including CMA-RA, ERA5, ERA-Interim, and FNL, this paper proposes an improved intelligent method for shear line identification by introducing a second-order zonal-wind shear. Climatic characteristics of shear lines and related rainstorms over the Southern Yangtze River Valley(SYRV) during the summers(June-August) from 2008 to 2018 are then analyzed by using two types of unsupervised machine learning algorithm,namely the t-distributed stochastic neighbor embeddin...     

Stratigraphic architecture and sedimentology of a Late Pleistocene subaqueous moraine complex,southwest Ireland

Glacigenic sediments exposed in coastal cliffs cut through undulatory terrain fronting the Last Glacial Maximum laterofrontal moraine at Waterville on the Iveragh Peninsula, southwest Ireland, comprise three lithofacies. Lithofacies 1 and 2 consist of interdigitated, offlapping and superimposed ice‐proximal subaqueous outwash and stacked sequences of cohesionless and cohesive subaqueous debris flows, winnowed lag gravels and coarse‐grained suspension deposits. These are indicative of sedimentation in and around small grounding line fans that prograded from an oscillating glacier margin into a proglacial, interlobate lake. Lithofacies 3 comprises braided river deposits that have undergone significant syn‐sedimentary soft‐sediment deformation. Deposition was likely related to proglacial outwash activity and records the reduction of accommodation space for subaqueous sedimentation, either through the lowering of proglacial water levels or due to basin infilling. The stratigraphic architecture and sedimentology of the moraine at Waterville highlight the role of ice‐marginal depositional processes in the construction of morphostratigraphically significant ‘end moraine’ complexes in Great Britain and Ireland. Traditional ‘tills’ in these moraines are often crudely stratified diamictons and gravelly clinoforms deposited in ice‐proximal subaqueous and subaerial fans. Copyright © 2011 John Wiley & Sons, Ltd.     

序贯一维型边缘检测新算法

本文提出一种既可用于从图象上提取具有某种用途的一维边缘,又可用于提取具有多种用途的二维边缘的序贯一维型边缘检测新算法。由于构成该算法重要组成部分的基础算子的作用,以及将二维问题化为一维问题求解而使其明显具有简单,快速、有效的特点。该算法还具有Abdou等所建议的边缘检测算子应具有的两个特性。     

What has seismic missed?

The relative efficiencies of alternative geometric patterns of both discrete borehole and continuous grid line search have been extensively discussed in the mathematical geology literature. However, an equally important problem has received virtually no attention: How to use a sample of properties of geologic anomalies detected by grid line search of a region to estimate systematically both the number and size distribution of geologic anomalies missed by the search. We show how estimation methods developed in the sample survey design literature can be adapted to this problem, and we apply these methods to data describing 94 anomalies identified by a seismic reconnaissance survey.