Influence of volume/mass on grain-size curves and conversion of image-analysis size to sieve size

Image analysis of aggregates does not measure the same size as sieve analysis. The size of aggregates, determined by sieve analysis, is presented with respect to the percent cumulative mass, whereas image analysis does not measure mass. Results are often presented in percent particles or percent area. Several researchers have claimed that more accurate volume and mass determinations are necessary for accurate construction of grain-size curves. In the present work, several methods for reconstructing volume and thus mass of aggregates from image analysis (IA) have been tested to see how they influence the grain-size distribution curves. The actual mass of the individual particles was found to have little or no influence on the grain-size distribution curve, which is normalized and thus insensitive to mass. Accurate conversion of image-analysis size to sieve size is dependent upon how particles pass through sieves. Most existing methods base their conversion of image-analysis size to sieve size on the intermediate axis, multiplied by some factor. The present work shows that there is no direct correlation between the intermediate axes and sieve size. A universal conversion of image-analysis size to sieve size has been developed, using the minimum-bounding square around the minimum projected area. This measure yields very good correlation with sieve-analysis results.     

分区绘制等值线的地下水污染质分布

使用ArcGIS 在不同水文地质分区中绘制等值线的方法,对长春市2004 年50 个水质采样点的数据进行空间统计分析,分区绘制了地下水重要组分NH+ 4 和Fe、Mn 的单项评价等值线图,分析了其分布及来源。结果表明,采用按水文地质条件分区绘制等值线的方法比原来由观测数据直接生成等值线的方法更趋合理。     

澳门地质概况

对澳门的泥盆系、第三系、第四系地层出露作了叙述，说明了花岗闪长岩、黑云母粗粒花岗石等几篑夺浆岩的分布及岩性特征，详细地论述了区内８条断裂构造，概述了碎石、建筑材料等矿产资料。     

光谱遥感数据波形分析法的应用

本文利用傅立叶波形分析算法处理了光谱反射率数据,把不同地物的光谱分解为特征意义明确,信息内涵丰富,对各种地物可分辨性强的各次谐波分量。诸谐波分量的参数——波幅和初相唯一地决定了其对光谱曲线的贡献和构形位置。试验表明傅立叶波形分析算法可以成为处理各种成像光谱仪获取的超维图像的有效工具。     

服务于海岸带环境与生态过程研究的e-Coastal Science平台系统架构设计

从海岸带环境与生态过程研究所面临的问题和需求角度出发,探讨了e-Coastal Science科研协同平台研发的必要性、框架结构、技术路线与支撑技术。即选择海岸带水域环境监测与模拟、入海河流流域空间水文与生态模拟、资源与环境胁迫下的海岸带管理决策三个密切相关的科学问题作为研究单元及平台系统研发的切入点,通过综合应用计算机科学和地球信息科学的基本理论与前沿技术,设计包含IT Infrastructure、GeoScience Platform和Coastal Science Platform的三个宏观层面系统平台,以及硬件平台、数据平台、模型模拟平台、协同与沟通平台和信息发布平台五个技术单元的系统框架,整个系统以Duckling1.2协同工作环境套件、Arc-GIS 9.3地理信息系统为主要支撑技术,并以专业模型工具研发及集成为技术特点。     

Comparative analysis of predictive methods for drought durations: a case of monthly and annual streamflow droughts in Atlantic Canada

Methods based on the recursive probability, the extreme number theorem, and Markov chain (MC) concepts were applied to predict drought lengths (duration) on the standardized (termed as standardized hydrological index, SHI) sequences of monthly and annual river flows from Atlantic Canada. Results of the study indicated that the MC-based method is the most efficient, reliable and versatile method for predicting drought durations followed by the extreme-number-based method. The recursive-probability-based method was found to be computationally intensive and less efficient, although it provided a powerful means for calibrating the empirical plotting position formula needed in the MC-based method. The Weibull plotting position formula turned out to be a suitable measure of the exceedance probability in MC methodology for predicting drought lengths in Atlantic Canada. Based on results, it can be inferred that the MC-based method can be extended to MC2 and higher-order chains for predicting drought lengths on SHI sequences. The predictive capability of the extreme-number-theorem-based method is limited only to independent or weakly first-order persistent SHI sequences.

EDITOR D. Koutsoyiannis

ASSOCIATE EDITOR Q. Zhang     

微型机点与多点间的后台通讯

本文介绍了一种用微型计算机IBM-PC/XT和一块XENIX四接口卡实现的点与多点间的后台通讯方案,并且详细介绍软件的实现方法及技术要点。     

基于HTML5 Canvas的态势符号标绘系统设计与实现

针对在线态势符号标绘系统如何快速渲染大数据量态势符号的难题,本文设计了在线态势符号标绘系统框架,研究了基于Canvas的态势符号库、态势符号的模型算法和多层Canvas绘制方法等关键技术,提高了在线态势符号标绘系统的渲染运行效率。将以上方法应用于实际,建设了浙江省在线态势符号标绘系统,并设计对比实验,验证该系统的运行效率,结果表明:本系统的运行速度优于传统态势符号标绘系统;随着绘制对象数据量的增大,该系统运行速度的优势更加明显。     

用SyGate实现一线多机上网

如今是科技信息时代，随着计算机的广泛应用，Internet已被越来越多的人所熟知。各市局气象网站也相继开通，为了充分利用现有网络软硬件资源和因特网资源，共享一个Modem使多台机器上网已是一个趋势，要实现这种功能需要软件支持，这就是代理服务器软件或网关软件，汕 尾市气象局通过YGATE（r）HomeNetwork4.0软件实现了局域网中一条电话线、一个Modem，一个ISP帐号多机上网。     

Excel与CAD结合在地质制图工作中的应用

采用CAD软件绘制地质图件时,常遇到不断重复简单的绘制命令,从而使得制图工作沉闷、低效、多错。介绍了利用Excel的编制函数功能与CAD命令窗口相结合的原理、方法及常用手段,通过实例来说明如何实现地质制图过程的快速、准确与高效。