警用空间大数据区位标识方法及其应用

警用空间大数据为警务工作的开展提供了丰富的决策依据,但也带来了一些挑战,如大数据整合复杂、多尺度信息关联困难、区位标识不唯一等,不利于警务改革的深入发展。本文提出了基于区域的位置标识方法来解决存在的问题,方法基于剖分网格设计了警用空间大数据的区位编码方法,并以户籍的区位标识为例进行说明,最后对其应用进行了展望,从而为警用空间大数据的有效组织和高效应用等提供了一种新的解决思路。     

地球剖分网格的地形量化模型

针对目前地形量化方法中,量化承载网格层级受限,且量化数据组织管理复杂的问题,提出了一种基于地球剖分网格的四边形网格的地形量化模型。该模型以GeoSOT地球剖分网格为支撑,通过GeoSOT网格编码实现了多层地形量化数据的关联、检索,为矢量数据和规则格网数据的量化处理、组织与存储以及量化数据聚合问题提供了方法。     

基于WGS-84椭球面的退化四叉树经纬线格网剖分

针对数字地球的发展和解决全球问题的需求,给出了一种基于WGS-84椭球面的全球离散格网剖分方法——退化四叉树经纬线格网;分析了格网剖分的特点,明确了格网单元行列定义和经纬度坐标;计算出不同剖分层次格网单元面积、边长的变化情况并与基于正球面的剖分进行了对比。结果表明该格网系统具有粒度相对均匀性、层次嵌套性、方向一致性、地理条带性和对称性、广泛数据兼容性等许多优良特征,对构建全球地理信息系统具有一定的实用价值。     

DEM 网格间距对重力近区地形改正精度影响及验证

利用分形随机算法建立平地、丘陵和山地3种精细地形仿真场景,将DEM逐级重采样为不同网格间距,分析不同DEM网格间距对3种地形的重力近区地形改正误差影响。发现随着DEM网格间距的增加,近区地形改正误差随之增大。对于平地,使用1∶10 000的DEM,网格间距为5m仍能够满足规范要求;对于丘陵地,使用1∶5 000的DEM,网格间距为2.5m能够满足规范要求;对于山地,使用1∶1 000的DEM,网格间距1m能够满足规范要求。通过消费级无人机获取丘陵地精细地形,验证地形仿真的结论,同时说明消费级无人机能够应用于重力近区地形改正。     

格网划分的Delaunay三角网快速生成算法

针对常见的三角网构建算法效率受查找三角形的约束的问题,该文提出了一种基于格网划分的Delaunay三角网快速生成算法,对传统逐点插入算法的点定位及LOP算法进行了优化。通过对离散点数据进行格网划分,将三角形面积坐标法与直线行走算法相结合,在点定位过程中可大幅度缩短搜索路径,快速定位到插入点所在的目标三角形。实验结果表明,改进后的算法兼顾了时间和空间的性能,执行效率明显提高,定位路径惟一且为最佳路径。     

A Terrain-Following Crystal Grid Finite Volume Ocean Circulation Model

A three dimensional hydrostatic finite volume ocean model has been developed to solve the integral dynamical equations. Since the basic (integral) equations are solved for finite volumes rather than grid points, the flux conservation is easily enforced, even on arbitrary meshes. Both upwind and high-order combined compact schemes can be incorporated into the model to increase computational stability and accuracy. This model uses a highly distorted grid system near the boundary. The lateral boundaries of each finite volume are perpendicular to x and y axes and the two vertical boundaries are not purely horizontal. Four types of finite volumes are designed to follow the terrain with four (Type-A), three (Type-B), two (Type-C), and one (Type-D) vertices in the lower surface. Such a terrain-following grid discretization has superior features to z- and σ-coordinate systems. The accuracy of this model was tested.     

Polymetamorphic origin of muscovite+cordierite+staurolite+ biotite assemblages: implications for the metapelitic petrogenetic grid and for P–T paths

Metapelites containing muscovite, cordierite, staurolite and biotite (Ms+Crd+St+Bt) are relatively rare but have been reported from a number of low-pressure (andalusite–sillimanite) regional metamorphic terranes. Paradoxically, they do not occur in contact aureoles formed at the same low pressures, raising the question as to whether they represent a stable association. A stable Ms+Crd+St+Bt assemblage implies a stable Ms+Bt+Qtz+Crd+St+Al₂SiO₅+Chl+H₂O invariant point (IP1), the latter which has precluded construction of a petrogenetic grid for metapelites that reconciles natural phase relations at high and low pressure. Petrogenetic grids calculated from internally consistent thermodynamic databases do not provide a reliable means to evaluate the problem because the grid topology is sensitive to small changes in the thermodynamic data. Topological analysis of invariant point IP1 places strict limits on possible phase equilibria and mineral compositions for metamorphic field gradients at higher and lower pressure than the invariant point. These constraints are then compared with natural data from contact aureoles and reported Ms+Crd+St+Bt occurrences. We find that there are numerous topological, textural and compositional incongruities in reported natural assemblages that lead us to argue that Ms+Crd+St+Bt is either not a stable association or is restricted to such low pressures and Fe-rich compositions that it is rarely if ever developed in natural rocks. Instead, we argue that reported Ms+Crd+St+Bt assemblages are products of polymetamorphism, and, from their textures, are useful indicators of P–T  paths and tectonothermal processes at low pressure. A number of well-known Ms+Crd+St+Bt occurrences are discussed within this framework, including south-central Maine, the Pyrenees and especially SW Nova Scotia.     

基于规则网格的复杂断层网络处理与建模

断层建模是三维地质结构建模中的主要过程之一。断层面建模过程中需要根据断层间的空间接触或者切割关系进行几何曲面的裁剪,目前方法利用三角网求交算法进行曲面裁剪,但是该算法处理复杂断层面切割关系时往往不稳定。笔者等提出了基于规则网格的复杂断层网络处理与自动化建模的方法和流程,详细讨论了基于网格化的断层网络模型形式化理论表达、建模流程中的断层网络空间关系构建以及相交裁剪处理算法等核心步骤。利用测试数据和煤矿三维地震构造解释数据进行了验证,表明该方法可以有效处理多条互相切割、主辅关系复杂的断层网络,具有较好的算法稳定性;与SKUA—GOCAD断层建模方法对比,能够减少交互过程,提高断层建模的自动化程度。     

气象灾害对江苏电网设备的影响及防御分析

随着全球气候特征的明显变化及江苏工业经济的高速发展,江苏电网设备因气象灾害所引发的故障呈现逐年递增的态势,污闪、风偏等故障次数明显增多.在广泛调研收集资料的基础上对江苏地区典型气象条件的时空分布、气象灾害形成原因进行统计分析,得出大风、雷暴、雾霾、覆冰天气条件下电网设备的故障特征,明确了故障时的主要气象要素及影响规律;同时结合江苏电网运行经验和目前采取的防御措施,提出加强电网设备抗灾设计、采用防灾新技术、建立电网灾害监测及预警系统的总体防御思路,可为具有类似气象灾害的电网设计、运行及事故预防提供重要参考.     

点到平面距离的点云数据压缩方法

针对三维激光扫描点云数据采集过密、冗余信息较多,现有压缩算法存在不足的问题,该文提出了基于点到平面距离的散乱点云压缩算法。将该算法与基于三角形法向量夹角和格网法两种现有算法的压缩结果进行比较,通过对比构建的空间三角网可以发现,该文算法对物体特征复杂的部位有较好的压缩效果,且在压缩率较高时,不会使较平缓的部位出现过度压缩而失真的情况。