A discrete square global grid system based on the parallels plane projection

We developed a direct partitioning method to construct a seamless discrete global grid system (DGGS) with any resolution based on a two‐dimensional projected plane and the earth ellipsoid. This DGGS is composed of congruent square grids over the projected plane and irregular ellipsoidal quadrilaterals on the ellipsoidal surface. A new equal area projection named the parallels plane (PP) projection derived from the expansion of the central meridian and parallels has been employed to perform the transformation between the planar squares and the corresponding ellipsoidal grids. The horizontal sides of the grids are parts of the parallel circles and the vertical sides are complex ellipsoidal curves, which can be obtained by the inverse expression of the PP projection. The partition strategies, transformation equations, geometric characteristics and distortions for this DGGS have been discussed. Our analysis proves that the DGGS is area‐preserving while length distortions only occur on the vertical sides off the central meridian. Angular and length distortions positively correlate to the increase in latitudes and the spanning of longitudes away from a chosen central meridian. This direct partition only generates a small number of broken grids that can be treated individually.     

Sample surveying to estimate the mean of a heterogeneous surface: reducing the error variance through zoning

One of the major sources of uncertainty associated with geographical data in GIS arises when they are the outcome of a sampling process. It is well known that when sampling from a spatially autocorrelated homogeneous surface, stratification reduces the error variance of the estimator of the population mean. In this study, we evaluate the efficiency of different spatial sampling strategies when the surface is not homogeneous. When the surface is first-order heterogeneous (the mean of the surface varies across the map), we examine the effects of stratifying it into first-order homogeneous zones prior to the usual stratification for a systematic or stratified random sample. We investigate the effect of this form of spatial heterogeneity on the performance of different methods for estimating the population mean and its error variance. We do so by distinguishing between the real surface to be surveyed (?), the sampling frame (?) including the choice of zoning, and the statistical estimators (Ψ). The study shows that zoning improves estimator efficiency when sampling a heterogeneous surface. Systematic comparison provides rules of thumb for choice of sample design, sample statistics and uncertainty estimation, based on considering different spatial heterogeneities on real surfaces.     

Equal arc ratio projection and a new spherical triangle quadtree model

A projection family, named Equal Arc Ratio Projection (EARP), is proposed in this paper, which has two kinds of geometric cases. Coordinates in the projections are determined by the ratios between four special arcs. The projection for spherical octahedron is derived, which is available for Dutton's Quaternary Triangular Mesh (QTM), and both projections of Goodchild's and Otoo's for QTM are found to be two special implementations of EARP. The icosahedral projection and thus the corresponding spherical triangle quadtree partition model are also developed. The partition model is compared with several other global grid models.     

分布式能源系统与电网的区域合作仿真

电网对分布式能源系统的态度很大程度上是出于利益的考虑,如果能够实现双赢,则二者共同合作满足区域用电将是缓解能源危机和供电压力的有效途径.应用Agent技术,将分布式能源系统和电网看作区域内的两类Agent,以实现各自预期利润为目标建立区域合作仿真模型,通过"调整策略-实现利润"的迭代过程获取二者双赢的边界条件及合作轨迹.最后以上海浦东国际机场能源中心热电联产系统为研究对象,验证该方法的有效性.     

Numerical simulation of overflow at vertical weirs using a hybrid level set/VOF method

This paper presents the applications of a newly developed free surface flow model to the practical, while challenging overflow problems for weirs. Since the model takes advantage of the strengths of both the level set and volume of fluid methods and solves the Navier-Stokes equations on an unstructured mesh, it is capable of resolving the time evolution of very complex vortical motions, air entrainment and pressure variations due to violent deformations following overflow of the weir crest. In the present study, two different types of vertical weir, namely broad-crested and sharp-crested, are considered for validation purposes. The calculated overflow parameters such as pressure head distributions, velocity distributions, and water surface profiles are compared against experimental data as well as numerical results available in literature. A very good quantitative agreement has been obtained. The numerical model, thus, offers a good alternative to traditional experimental methods in the study of weir problems.     

基于工作流的海图生产管理系统设计

针对目前海图生产管理信息化和自动化程度落后的现状,本文在对工作流相关技术进行分析基础上,结合海图生产管理流程的特点,给出了海图生产管理系统的具体设计,并运用工作流管理工具myApps进行了系统实现.系统设计合理、使用方便,满足对海图生产流程的有效监管和调度.     

基于SOA网格管理模型的空间信息共享平台设计

现有的空间信息共享平台框架及开发模式较难灵活地完成地理信息服务和应用系统多层次的融合、空间信息资源整合及空间信息的共享等问题。本文通过一种基于SOA网格管理模型(service-oriented architecture,SOA)的空间信息共享平台设计框架,结合空间信息多级网格和SOA服务体系框架的优点解决了在广域网络环境下整合空间信息资源从而有利于空间信息共享的问题,并通过多级地图缓存服务,即利用对各种比例尺的地图数据在计算机内存中的临时存储,来提高用户在编辑、特征渲染和标注等操作的响应速度的技术来解决空间数据的传输和显示等问题。     

浅谈ISO 9001质量管理体系在房产测绘中的应用

房产测绘关系千家万户的切身利益,测绘质量一直是社会关注的热点,因此对于提高房产测绘的质量管理也一直是测绘企业的重点课题。根据房产测绘质量管理的特点,依据GB/T 19001-2008质量管理体系要求,结合工作实践,对实施ISO 9001质量管理体系前后管理状况进行对比,阐述了实施和持续改进测绘质量管理的措施和建议。     

建设用地审批管理系统建设与设计

文章提出了建设用地审批管理系统建设目标和原则。以山东省建设用地审批管理为例,给出了建设用地审批管理系统的体系架构设计和实现,并对建设用地审批管理系统建设的关键技术进行了讨论。     

城市大比例尺基础空间数据库动态更新机制研究与实现

首先针对长期困扰城市大比例尺空间数据库建设的＂更新冲突＂和＂更新速度慢＂等问题进行了探讨,根据城市规划空间数据实际生产特点,建立空间数据库动态更新机制,将数据更新与实际工作业务结合起来,按需更新,事件驱动,建立了一套动态的基础空间数据库更新机制,并在生产中得到实际应用。