遥感技术在我国滑坡研究中的应用综述

中国滑坡遥感研究与应用已有30多年的发展历史,作为滑坡调查的主要手段在大型工程建设中的滑坡灾害调查及危险性评价中发挥了重要作用。从4方面阐述了遥感技术在我国滑坡研究中的应用：① 区域滑坡灾害遥感调查;② 大型单体滑坡遥感调查;③ 滑坡灾害遥感监测;④ 遥感应用于滑坡风险评估。随着遥感技术理论的逐步完善和遥感图像空间分辨率、时间分辨率与波谱分辨率的不断提高,遥感技术已成为滑坡灾害调查、动态监测与预警、灾情实时调查与损失评估等工作中不可缺少的重要手段之一。     

滑坡高分辨率遥感多维解译方法及其应用

目的:高分辨率遥感影像技术的发展使得对于地质灾害体的要素组成、形态结构的遥感解译成为可能。目前,遥感影像解译存在着过度依赖影像色彩、纹理、阴影等光学要素,片面追求影像解译标志,DEM数据利用程度低,对基于DEM、GIS的影像复合分析、空间分析、3D可视化等技术方法的应用较少等问题。方法：本文以灾前灾后高精度DEM和高分辨率遥感影像为基础,探讨了地质灾害滑坡的一维、二维、三维三种遥感解译方法,分析了三者之间的互补关系,并应用三种遥感解译方法对贵州关岭“6.28”特大滑坡进行了遥感解译分析,文章最后对有关滑坡多维遥感解译方法体系的建立进行了讨论。结果：研究结果表明：滑坡高分辨率遥感多维解译方法中,一维高程曲线计算、二维影像对比分析、三维场景精细解译分别属于滑坡遥感解译的初判方法、动态分析方法、定量计算方法;结论：其中,一维高程曲线计算为滑坡遥感的二、三维解译提供了有关滑坡崩塌区、滑坡区、堆积区的可能分区参考框架,而二维影像对比分析向三维场景精细解译的发展则体现了以人机交互方式为主要手段的滑坡高分辨率遥感影像解译由定性监测向定量计算的发展。     

基于高分辨率卫星遥感影像滑坡提取方法研究现状

滑坡具有强大的爆发力和破坏性，是世界上发生频率较高的自然灾害之一，给人们的生命财产造成了严重的损害。灾后准确快速的提取滑坡，获取滑坡的分布范围，对滑坡灾害调查及危险性评估极为重要。围绕基于高分辨率卫星遥感影像监测滑坡的方法进行了调研，首先介绍了滑坡在高分辨率卫星遥感影像上的解译特征，而后论述了滑坡提取方法和精度评价分析方法的研究进展，最后总结了当前方法的优势与不足，以及未来研究的发展方向。结果表明：深度学习方法具有较大的潜力，未来应加强深度学习与其他自动化解译方法的结合在滑坡监测中的应用，解决样本规模对模型结果的影响，实现模型的可迁移性，提高其自动化程度。     

利用NDVI时间序列识别汶川地震滑坡的分布

利用MODIS NDVI产品,生成了全年16天间隔的NDVI时间序列,再经过Savitzky-Golay滤波后消除了云的影响,可以用来识别滑坡。假设2007年、2008年研究区土地利用状况基本不变,对比2007年和2008年两年的NDVI序列,并结合汶川地震的发生时间,可以识别出研究区发生滑坡的区域分布。结合平武县30mETM目视解译滑坡结果,对自动识别方法进行了验证。结果表明:MODIS识别出的滑坡与目视解译结果匹配较好。在此基础上,将本文方法应用到受汶川地震影响最严重的13个县区级行政区,并综合研究区坡度信息,识别出了汶川重灾区滑坡分布概图。     

词袋特征支持下的无人机影像滑坡解译模型

川西地区滑坡灾害频发,给当地人民生命、财产安全带来了极大威胁。如何利用无人机高分影像构建滑坡灾害解译模型是实现快速自动解译的关键。针对该问题,首先,对比了多种影像特征提取方法,然后将词袋特征和支持向量机引入到构建滑坡灾害解译模型中,提出了一种基于词袋特征的无人机影像滑坡灾害解译模型。最后,选取512汶川地震及420芦山地震系列无人机影像构建了滑坡灾害样本库,基于该样本库进行了实验,分类准确度达到76%,相比于传统目视解译在效率上有明显优势。分析表明,所提出方法可用于高分影像滑坡自动解译。此外,该模型可用于大面积高分影像快速山地滑坡灾害定位,可实现滑坡灾害的快速检测,对于灾后应急具有一定的指导作用。     

资源三号卫星在汶川震区滑坡快速识别中的应用方法研究

针对当前采用野外人工调查和遥感目视解译获取地震灾区滑坡信息存在主观性强、耗时费力等缺点。以汶川震区为实验区,应用资源三号(ZY-3)卫星影像,采用多尺度最优分割方法构建多层次识别对象,融合光谱、纹理、几何等影像特征和地形特征建立多维滑坡识别规则集合,以及基于高分辨率影像认知模式与场景理解过程提出滑坡分层识别模型,从而实现滑坡空间分布及其滑源区、滑移区和堆积区的快速识别。通过实验结果发现最低识别精度为82.97%,而滑坡的堆积区最容易识别。研究结果验证了该方法及资源三号卫星数据快速识别地震滑坡信息的有效性,可为震区滑坡调查提供技术支持,并可促进国产卫星的推广应用。     

典型地震次生地质灾害多光谱遥感影像特征图谱研究

为从地质灾害多光谱遥感影像资源中挖掘有用的信息,形成标准化、定量化的地质灾害遥感判读知识,进行地震次生地质灾害遥感影像特征图谱研究。以"5·12"汶川地震重灾区地震次生地质灾害滑坡、碎屑流和崩塌为例,首先提取灾害体单元的遥感影像,选取其光谱、纹理和色彩方面的20种遥感影像特征参数并统计参数值;然后对特征参数进行归一化处理,并通过主成分分析得到利用第一、第二、第三主成分表达的各类地震次生地质灾害的影像特征图谱。经过测试样本验证,上述几类图谱可表征相应地震次生地质灾害类型的影像特征。揭示了不同类型地震次生地质灾害遥感影像特征之间的关系,并为遥感影像中灾害体的识别提供了定量化和可视化的知识。     

尼泊尔震后Rasuwa区山地灾害遥感调查

针对尼泊尔4·25Gorkha地震诱发山地灾害的现象,基于多源光学遥感数据,使用目视解译方法分析了震前和震后地物特征的变化,调查了Rasuwa区影响抗震救灾的公路沿线滑坡、堰塞湖的空间分布。结果表明:本次地震新形成的大型滑坡较少,大部分为中小型滑坡、浅层滑坡及碎屑流、崩塌和落石等灾害,并有堰塞湖。而在影像上能清晰识别的灾害点有15处,其中3处危害较大,分别为Langtang滑坡、Resuo滑坡和1处堰塞湖。Langtang滑坡造成了严重的破坏。     

乌兰布和沙漠高分辨率遥感影像梭梭林解译方法探讨

利用ALOS、SPOT5高分辨率遥感影像,结合野外调查,完成了乌兰布和沙漠研究区遥感影像信息的目视解译及植被制图,并结合GPS野外样点进行精度评价,解译精度为93.3%,梭梭林面积为165 410.62 hm²,占乌兰布和沙漠地区总土地面积的17.27%。最后,对乌兰布和沙漠遥感影像梭梭林解译的方法进行了探讨。     

林地山区滑坡遥感的最优融合方法及应用

滑坡作为造成巨大经济损失和人员伤亡的地质灾害之一,越来越引起社会的高度重视。为精确识别林地山区中的滑坡灾害,以2020年7月6日发生在湖南省常德市石门县南北镇潘坪村的雷家山滑坡为研究对象,使用不同的融合方法进行Sentinel-1A C波段干涉宽幅的地距多视产品和Sentinel-2A多光谱2A级光学影像融合,得到主成分分析融合方法对分贝化处理后的S1A VV极化影像与S2A影像融合效果最优,采用支持向量机方法分别对最优融合影像和原始S2A影像进行滑坡识别,最后使用S2A影像滑坡目视解译结果为检验标准对支持向量机滑坡识别结果进行精度评价,同时以2020年7月21日发生在湖北恩施屯堡乡马者村的沙子坝滑坡作为案例检验该方案的可推广性。结果表明：与单独使用光学影像进行研究区滑坡识别相比,使用最优融合影像滑坡识别的准确率由95.24%提升到了96.65%,滑坡提取质量也由87.18%提升到了91.84%,滑坡的漏识别和过度识别均有所降低,说明光学影像和合成孔径雷达影像融合的研究方案具有可推广性,能提高林地山区滑坡识别的准确率,可以更好地为滑坡风险评估、灾后应急调查以及灾后恢复重建等提供有价值的...     

典型地质灾害遥感应急调查研究

采用多源遥感影像数据,以平武县为例,进行了地质灾害调查分析,弥补了单一数据源信息提取能力的不足,尤其是在云、雨等气候恶劣条件下,无法清晰获得光学图像的时候,雷达影像可以提供丰富的可用信息,解译效果较好,这对加快应急信息化建设,减灾救灾业务具有重要借鉴意义。     

Regional assessment of geohazard recovery eight years after the Mw7.9 Wenchuan earthquake: a remote-sensing investigation of the Beichuan region

The earthquake of 12 May 2008 in Wenchuan County, Sichuan Province, China, devastated the entire Beichuan region. Sitting at the intersection of the Yingxiu-Beichuan and Pengguan faults, the region experienced seismic intensities of VIII–XI on the Liedu scale. High seismic intensity combined with inherent geomorphological and climatic susceptibility to slope failure resulted in widespread co-seismic geohazards (slope failures of various types), which decimated the region. The seismic characteristics of the Wenchuan earthquake and the co-seismic geohazard distribution in relation to various conditioning factors have previously been examined in depth. However, there has been a lack of regional assessment of temporal and spatial recovery from co-seismic geohazards. Triggered by the authors’ field observation of rapid recovery, this study presents a temporal series of geohazard maps, produced by manual interpretation of satellite imagery, to present an initial assessment of changes in geohazard occurrence in the Beichuan region since the Wenchuan earthquake. In particular, landscape recovery at the co-seismic geohazard sites, as indicated by re-vegetation, is analysed based on temporal/spatial characteristics of geohazard distribution, in relation to co-seismic deformation, distance from the rupture zone and slope angle. Eight years after the Wenchuan earthquake, the overall recovery stands at 65.48%, with approximately uniform annual rates of recovery at 13.45% a year between 2009 and 2011 and 10.56% a year between 2012 and 2016. Whilst co-seismic geohazards are concentrated on the hanging wall of the seismic fault, landscape recovery is more significant in the very highly deformed zone than in other areas. Recovery has been the greatest on slopes of <50^° and peaks on 40^°–50^° slopes, where the area occupied by co-seismic geohazards was the largest. The block-slides and rock topples, which characterize high angle slopes, show much slower recovery, possibly due to greater instability and the lack of soil to support re-vegetation.     

基于GIS的三峡库区滑坡稳定性评价系统

基于三峡库区三期地质灾害防治工程地质勘查技术要求,利用GIS技术设计三峡库区滑坡稳定性评价系统,为预警指挥系统提供稳定性定量评价支持。阐述基于GIS的三峡库区滑坡稳定性评价系统建设目标和内容,分析系统的总体设计、逻辑结构和功能模块设计,给出系统的实现界面。     

Probabilistic identification of subsurface gypsum geohazards using artificial neural networks

Subsurface gypsum dissolution hazards imply risks to the construction and operation of new transport infrastructure including subsidence, cavity collapse and cavity flooding. This is a concern in Abu Dhabi, United Arab Emirates, where gypsum geohazards are observed and an extensive transportation network is planned. This paper proposes an artificial neural network (ANN)-based approach for the prediction of underground gypsum. Moreover, the approach is developed to provide the expected probability of gypsum presence and to generate gypsum hazard maps. Such maps provide both a general planning instrument and an input for the decision support systems. An application to Masdar City, Abu Dhabi, is discussed at the site of a planned metro line. Twenty-one boreholes are used to train and validate the ANN that is used to produce a 3D geological model identifying the expected presence of gypsum. Most significantly, the application illustrates how gypsum hazard maps can be obtained at any required depth providing planners and designers with essential information for risk assessment and management.

     

Effects of experience on microcomputer use in primary schools: results of a second survey

Abstract Following an initial survey of microcomputer use in Hertfordshire primary schools, a second, follow-up survey was conducted two years later to examine how experience had changed attitudes and use. This second survey provided detailed information of microcomputer provision, classroom use, and an analysis of factors which were related to use. As before, the survey was in two parts: an initial questionnaire to collect information from both headteachers and teachers. Some changes were observed across surveys which suggested that teachers would make more innovative use of the microcomputer in the future given sufficient training. As before, children's access was limited, and they mostly used drill and practice-type software in small groups (although child-directed programs were becoming a little more popular). Both surveys indicated that microcomputers offered a focus for cooperative activity which had not been predicted. Interestingly, the type of software mainly used was found to be related to children's cooperative behaviour, and their motivation for work.     

A survey of microcomputer use and provision In primary schools

Abstract An exhaustive survey of Hertfordshire primary schools was completed which provides detailed information of microcomputer-provision, classroom use, headteachers' and teachers' aims and attitudes, and an analysis of factors which influence use. The survey was in two parts: an initial questionnaire to identify the extent of microcomputer ownership, and a main questionnaire to collect information from both headteachers and teachers who were using microcomputers. In general, most schools possessed microcomputers, but children's access was limited, and it would appear that drill and practice type programs were most frequently used. The extent and type of use was found to be affected by a number of factors.     

绝热量子优化算法研究进展

绝热量子优化计算于2001年首次提出,它基于绝热量子演化研究NPC组合优化问题,是量子计算的领域热点。主要回顾了绝热量子优化算法研究领域所取得的进展,阐述绝热量子优化算法研究所采用的主要方法和关键技术,最后分析绝热量子优化计算的发展趋势。     

Students' attitudes towards programming: The effects of structured walk-throughs

The effectiveness of classroom team activities in eliciting more favorable attitudinal outcomes was empirically assessed with a sample of 215 undergraduate Business Administration majors enrolled in an introductory COBOL programming course. For each assigned program. students in the experimental group read and critiqued team members' program listings.Attitudinal outcomes were measured by a “Programming Attitude Survey” constructed for the experiment. This survey consisted of positive and negative statements about programming which were measured on a Likert-type scale. The survey was administered at the beginning (pre-test) and at the end (post-test) of the quarter. Analysis of covariance was used to statistically adjust post-test responses for pre-test responses. Nonparametric tests for differences in proportions were also used.The experimental group exhibited statistically significant differences (P < 0.05) in the following areas: (a) more favorable index scores on one-third of the survey items analyzable with covariance methods, (b) a greater proportion of positive pre-test-to-post-test changes in responses to the survey and (cl a greater proportion of more favorable post-test responses to the attitude survey.The findings provide empirical support for incorporating team activities into the programming learning process to more effectively develop positive attitudinal outcomes in students.     

基于GPS和神经网络的滑坡位移监测算法

针对使用GPS接收机进行滑坡位移监测时,单点GPS定位误差较大的问题,提出了一种基于GPS和神经网络的滑坡位移监测算法。GPS接收机在滑坡发生之前和滑坡发生之后测得的定位数据耦合在一起,不是线性可分的。采用具有非线性可分特性的神经网络,把耦合在一起的定位数据分成两类,一类属于未滑坡的GPS数据,另一类属于发生滑坡的GPS数据,避免了对GPS定位误差这一非线性非高斯问题进行准确建模的过程。利用GPS接收机测得的样本训练集训练神经网络,用训练后的神经网络模型来验证测试集的分类效果。实测实验结果表明,对于低精度的GPS接收机,当滑坡程度分别达到3米、5米、8米时,训练样本分类正确率分别是95.85%、99.23%、99.99%,测试样本分类正确率分别是82.94%、89.44%、91.05%,说明所提出的算法适用于较大程度的滑坡。     

IT under school-based policies for Initial Teacher Training

Abstract This paper describes aspects of a survey carried out amongst students and staff in the use of Information Technology (IT) in the initial training of teachers at the University of Leeds during the academic year 1992/93. The survey attempted to chart the IT profiles of students during their Post Graduate Certificate of Education (PGCE) year, assessing their initial and final IT confidence, their IT activities and problems they encountered, and the extent to which IT was used on their teaching practice. The results of the survey are discussed in the light of the changes which are taking place in the training of teachers.