管网测绘数据的GIS建库

文章阐述了管网测绘数据的GIS建库的基本方法 ,以及计算机监理查错程序对勘测成果的检测。     

用ESDA技术从GIS数据库中发现知识

从GIS数据库中可发现许多知识，这在GIS界已引起了相当的重视。ESDSA技术注重研究数据的空间依赖与空间异质性，在知识发现中用于选取感兴趣的数据子集，并可初步发现隐含在数据中的某些特征和规律。一些标准全程和局部空间统计包括MoranI,GearyG,G统计以及LISA等是ESDA技术的基本核心内容之一。在目前专家系统尚不成熟的条件下，充分利用GIS的可视化和空间分析技术是实现ESDA技术与GIS紧密完全结合的关系。实例说明在ESDA技术结合其它相关领域的知识从GIS数据库中发现知识的方法是可行的。     

遥感影像镶嵌时拼接缝的消除方法

对现有的影像并接缝消除方法的优缺点进行了分析,提出了拼接缝消除的强制改正方法,并用大量的实际图像进行了试验。结果表明：所提出的方法具有较好的拼接缝消除效果,且算法简单,易于实现,可以处理彩色和黑白等多种图像。     

钢卷尺悬空改正及其技术指标

为保证钢卷尺悬空丈量与水平丈量的统一,本文对钢卷尺垂曲改正进行推导。为便于改正计算,介绍国内几种型号钢卷尺的技术指标。     

测绘职业技能鉴定命题技巧初探

由于当前测绘知识技术更新速度极快,使得测绘职业技能鉴定题库也在不断地更新当中,这就要求命题工作者除了掌握应有的测绘专业技术知识之外,还要不断探索、深入研究命题技术和命题技巧.本文的研究,为进一步实现测绘职业技能鉴定命题工作科学、客观、统一、规范具有一定的现实意义.     

Halin图的色数问题

Halin图G=T∪C,其中T为每一非悬挂点(内点)度数至少为3的平面树,C为连接T的所有悬挂点的圈.文章分别讨论了Halin图的星色数、面色数及分数色数.     

Origin and Evolution of Aquitard Porewater in the Western Coastal Plain of Bohai Bay,China

High‐salinity paleowater from low‐permeability aquitards in coastal areas can be a major threat to groundwater resources; however, such water has rarely been studied. The chemical and isotopic compositions of porewater extracted from a 200‐m‐thick Quaternary sedimentary sequence in the western coastal plain of Bohai Bay, China, were analyzed to investigate the salinity origin and chemical evolution of porewater in aquitards. Porewater samples derived at depths shallower than 32 m are characterized by Cl‐Na type saline water (total dissolved solids [TDS], 10.9–84.3 g/L), whereas those at depths greater than 32 m comprise Cl·SO₄‐Na type brackish water (TDS, 2.2–6.3 g/L). Saline porewater is interpreted as evaporated seawater prior to halite saturation, as evidenced by Cl‐Br relationships. Although substantial dilution of saline porewater with meteoric water is supported by a wider Cl^? range and δ²H‐δ¹⁸O covariance, the original marine waters were not completely flushed out. The deeper brackish porewater is determined to be a mixture of fresher porewater and brine groundwater and had a component of old brine of less than 10%, as indicated by a mixing model defined using δ²H and Cl^? tracers. Porewater δ²H‐δ¹⁸O relationships and negative deuterium excess ranging from ?25.9‰ to ?2.9‰ indicate the existence of an arid climate since Late Pleistocene in Tianjin Plain. The aquitard porewaters were chemically modified through water‐rock interactions due to the long residence time.     

适用于县级大比例尺测绘的平面直角坐标系整合方法与实践

县(市)开展大比例尺测图时,应首先收集已有的测绘成果及采用的平面直角坐标系统。当测区处于国家统一3°投影带边缘或测区高程较大时,为满足每千米长度变形值不大于2.5 cm,必须建立相应的地方平面直角坐标系。本文针对某县已经建立的基于多种平面直角坐标系的测绘成果,介绍了一种将现有测绘成果转换到地方平面直角坐标系的方法。     

Very Large Eddy Simulation of Cavitation from Inception to Sheet/Cloud Regimes by A Multiscale Model

The cavitating flow in different regimes has the intricate flow structure with multiple time and space scales. The present work develops a multiscale model by coupling the volume of fluid(VOF) method and a discrete bubble model(DBM), to simulate the cavitating flow in a convergent-divergent test section. The Schnerr-Sauer cavitation model is used to calculate the mass transfer rate to obtain the macroscale phase structure, and the simplified Rayleigh-Plesset equation is applied to simulate the growing and collapsing of discrete bubbles. An algorithm for bridging between the macroscale cavities and microscale bubbles is also developed to achieve the multiscale simulation. For the flow field, the very large eddy simulation(VLES) approach is applied. Conditions from inception to sheet/cloud cavitation regimes are taken into account and simulations are conducted. Compared with the experimental observations, it is shown that the cavitation inception, bubble clouds formation and glass cavity generation are all well represented, indicating that the proposed VOF-DBM model is a promising approach to accurately and comprehensively reveal the multiscale phase field induced by cavitation.     

浙江省海宁市TM图像土地利用自动分类精度评价方法的试验研究

按照国家土管局土地利用现状分类标准,利用叠合的海宁市长安镇１∶１万同时期土地详查电子地图的全域地面实况数据,在遥感图像处理常规分类方法的范畴内,采取最大程度利于提高分类精度的措施,所得的分类精度上限为６５％。研究表明,通常在试验区的小块局部中选择训练样本和选择评价分类精度的参考像元,对精度评价有显著影响,参考像元质量和数量的限制很可能是这些年来一些同类研究报道了较高分类精度结果的主要原因