GB-SAR变形监测技术研究现状与展望

地基合成孔径雷达（GB-SAR）技术是近十多年发展起来的地面主动微波遥感技术,可进行非接触、高精度、大范围、远距离的变形监测,在变形监测领域具有重要意义。本文首先介绍了GB-SAR干涉测量基础理论和研究现状,归纳了目前主要的GB-SAR系统,详细列举了现有系统的关键参数;进而分析了GB-SAR技术在基础设施、滑坡、矿山、冰川运动及文物保护等变形监测领域应用的优势和不足,总结了地基雷达系统在实际应用中面临的挑战;最后从多维形变、大气改正等方面对其应用前景进行了展望。     

Measurement of oxygen production and demand in lake waters

An analysis of the New Zealand whale stranding record by M. W. Bradyn. Science and Research Series 29. ISSN 0113–3713, ISBN 0–478–01278–6. Available from Department of Conservation, Wellington. Price: $15.00.

Fish quality control by computer vision, edited by L. F. Pau and R. Olafsson. Published by Marcel Dekker, Inc.     

Prediction of sediment yield by coupling Kalman filter with instantaneous unit sediment graph

An instantaneous unit sediment graph (IUSG) model in conjunction with Kalman filter was investigated for prediction of sediment yield from an upland watershed in Northwestern Mississippi. The state vector of the watershed sediment yield system was constituted by the IUSG and then the sediment yield was estimated by the IUSG model using Kalman filter. The initial values of the state vector were assumed as the average of the IUSG values and the initial sediment yield estimated from the average IUSG. The IUSG model using Kalman filter with a recursive algorithm accurately predicted sediment yield from watershed W‐5, Mississippi. The filter allowed the IUSG to vary in time, increased the accuracy of the IUSG model, and reduced physical uncertainty of the sediment yield process in the watershed. Copyright © 1999 John Wiley & Sons, Ltd.     

水泥搅拌桩在天津沿海软基加固中的应用

大型工程场地挖填方地基处理面积大、工期紧,需要及时、快速掌握地基加固处理的质量情况,以确保工程质量和进度;同时为确保工程的安全稳定,大型工程对地基土体加固效果的均匀性往往有较高要求。地基土体压实效果常规检测方法主要有原位载荷试验、原位灌砂和土样测试等方法,这些方法要么设备笨重、耗时,要么会造成已加固的地基土体的破坏,从而无法对地基土体展开快速、连续检测。为克服上述问题,本文采用考虑道间时差相位的多道瞬态瑞雷波探测方法,辅以抽样点的取土试验测试,对某大型工程填方地基土体压实加固效果展开快速、连续检测,获得地基土体弹性波速的三维连续图像,进而生成附加应力影响深度范围内地基土体的瑞雷波相速度成像水平切片和地基土体深度平均压实系数水平分布成像。这些地基土体成像结果可以较好地反映出地基土体压实加固效果,从而为地基土体加固质量评价提供重要参考。

     

The effects of survey frequency on estimates of scour and fill in a braided river model

An erratum has been published for this article in Earth Surface Processes and Landforms 27(7) 2002, 795. Estimates of scour and fill in rivers that are derived by differencing topographic surfaces are known to be negatively biased by local compensation of scour and fill between surveys but the magnitude of bias is not well known. This study examines the effect of survey frequency on volumes of scour and fill over a period of active channel braiding in a small‐scale river model. A 100 min, high temporal resolution time series of digital elevation models is artificially coarsened by selectively removing models. The resulting four overlapping time series have survey intervals of 10 min, 20 min, 50 min and 100 min. Cumulative scour and fill volumes for the 100 min period are compared between the four series. It is concluded that the decay in measured volumes of scour and fill with increased survey interval can be described using inverse functions. Cumulative scour–fill volumes are approximately 420 per cent greater over the study period for 10 min survey intervals than for a 100 min interval. After the 100 min period of competent flow, nearly 65 per cent of the channel area experienced significant compensation of scour and fill. Several compensation mechanisms were identified in association with braided channel kinetics, including lateral channel migration, the migration of bed forms, and channel avulsion. It is demonstrated that by negatively biasing scour, fill and net estimates, this error significantly affects morphological approaches to the estimation of bed load sediment transport. Copyright © 2002 John Wiley & Sons, Ltd.     

粤港澳大湾区红树林长时间序列遥感监测

随着遥感数据量的爆发式增长,对变化过程分析的精细化要求与本地算力不足之间的矛盾日益突出。GEE（Google Earth Engine）地理云平台的出现,解决了用户算力紧张的行业痛点。本文以粤港澳大湾区为研究区,在GEE的支持下,构建1987年—2020年年度湿地分类数据集,分析大湾区红树林的时间阶段性特征和空间扩张过程,结合连续长历时分析对变化时间点的准确识别,揭示了保护区设立与滩涂造林等工程在红树林保护与修复中的积极成效。主要结论有：（1）截止到2020年,大湾区共有红树林2174 ha,81%的红树林集中在深圳湾、淇澳岛和镇海湾;（2）大湾区的红树林经历了由平稳发展（1987年—2003年）到快速增长（2003年—2020年）的变化过程,其主要增量来源于镇海湾（40%）和淇澳岛（28%）;（3）淇澳岛和镇海湾的红树林仍处于快速增长期,但淇澳岛增速最快,从2002年至今面积翻了30倍,深圳湾则在早期的快速增长（1987年—2009年）后进入平稳期（2009年—2020年）;（4）由于保护区设立时间较早,深圳湾成为大湾区唯一一个形成稳定核心区的红树林分布区,镇海湾虽然拥有最大的红树林面积,但林道狭窄,景观破碎,生态系统反而更加脆弱;（5）设立自然保护区和滩涂造林都对红树林面积增长起到了积极作用。本研究为大湾区海岸带湿地生态系统保护与修复提供科学的证据支持,对沿海生态屏障建设具有一定的指导作用。     

结合全站式三维扫描与建筑设计坐标的复杂曲面检测

针对赛道复杂双曲面结构的高精度要求,以及无BIM模型加以参照这一现状,本文以北京冬奥会雪车雪橇赛道为例,首先采用全站式三维激光扫描仪对赛道混凝土喷射形成的曲面进行扫描,并结合建筑设计坐标完成夹具剖面特征点检测;然后依据设计三维坐标进行建模;最后将模型与扫描点云数据进行对比检测,生成三维色谱图,以掌握任意点的偏差值。结果表明,该方法既能进行关键特征点位的检测,又能全面掌握整个复杂曲面的偏差情况,满足测量的高精度要求,可为今后此类复杂曲面检测工程提供思路与技术参考。     

测量机器人ATR智能测量程序研制

依据我国三角测量、工程测量等行业测量规范的有关规定,以GeoC++为开发平台,研究开发了三角网野外数据采集的智能化测量程序,可用于控制网建立过程中的数据自动采集、超限数据的自动判别与重测,有效提高了数据采集的效率和数据处理的自动化程度。     

单幅图像几何量测研究进展

为进一步促进单幅图像几何量测理论和技术的研究深化,拓展其应用领域,对近十年来单幅图像几何量测技术和方法进行了分析和总结。首先总结提炼了单幅图像几何量测的基本原理,即直接几何量测和间接几何量测,论述了各自的数学背景;在此原理下,将单幅图像几何量测方法分为基于单应的量测方法和基于几何关系的量测方法,并对各类算法的原理、约束条件、求解方法进行了详细讨论,阐明了算法的优缺点。