Object-based classification of cloudy coastal areas using medium-resolution optical and SAR images for vulnerability assessment of marine disaster

Efficient and accurate access to coastal land cover information is of great significance for marine disaster prevention and mitigation.Although the popular and common sensors of land resource satellites provide free and valuable images to map the land cover,coastal areas often encounter significant cloud cover,especially in tropical areas,which makes the classification in those areas non-ideal.To solve this problem,we proposed a framework of combining medium-resolution optical images and synthetic aperture radar(SAR)data with the recently popular object-based image analysis(OBIA)method and used the Landsat Operational Land Imager(OLI)and Phased Array type L-band Synthetic Aperture Radar(PALSAR)images acquired in Singapore in 2017 as a case study.We designed experiments to confirm two critical factors of this framework:one is the segmentation scale that determines the average object size,and the other is the classification feature.Accuracy assessments of the land cover indicated that the optimal segmentation scale was between 40 and 80,and the features of the combination of OLI and SAR resulted in higher accuracy than any individual features,especially in areas with cloud cover.Based on the land cover generated by this framework,we assessed the vulnerability of the marine disasters of Singapore in 2008 and 2017 and found that the high-vulnerability areas mainly located in the southeast and increased by 118.97 km2 over the past decade.To clarify the disaster response plan for different geographical environments,we classified risk based on altitude and distance from shore.The newly increased high-vulnerability regions within 4 km offshore and below 30 m above sea level are at high risk;these regions may need to focus on strengthening disaster prevention construction.This study serves as a typical example of using remote sensing techniques for the vulnerability assessment of marine disasters,especially those in cloudy coastal areas.

Reflections on Plain Greening in Coastal Urban Areas： A Case Study of Plain Greening in the Main Urban Area of Taizhou

The current situation,existing problems and characteristics of greening in the main urban area of Taizhou were analyzed,and the construction ideas and safeguard measures of plain greening in urban areas in the new era were put forward.

Spatio-temporal Dynamic Patterns of Rural Area Development in Eastern Coastal China

The aim of this study is to evaluate the current state of rural area development at the county level in the eastern coastal China. An evaluation index system including 18 factors was developed, and a rural development index (RDI) was constructed to evaluate rural development state in 2000, 2004, and 2008. The quantitative evaluation indicated the following results. 1) This study derived four dominating components by means of principal component analysis, which can explain 78.2% of the total information, namely agricultural production input, the basic condition of agriculture, the comparative effectiveness of grain production, and the household′s own basic conditions. 2) Since the turn of the new millennium, the rural area in the eastern coastal China has experienced a rapid development in general. Well developed, developed, moderately developed and undeveloped rural areas respectively occupied 29.32%, 22.33%, 21.91%, and 10.51% in 2008. 3) The countryside had maintained a sound momentum of developing trend between 2000 and 2008, while the rural development in the eastern coastal China lacked sustainability. And 4) industrialization, urbanization, original economic basis, and location are four major driving forces of the disparity of rural area development in the eastern coastal China. Given these results, the strategies and policies for the improvement of each rural group were put forward.

Optimum segmentation of simple objects in high-resolution remote sensing imagery in coastal areas

The optimum segmentation of ground objects in a landscape is essential for interpretation of high-resolution remotely sensed imagery and detection of objects; and it is also a technical foundation to efficiently use spatial information in remote sensing imagery. Landscapes are complex system composed of a large number of heterogeneous components. There are many explicit homogeneous image objects that have similar spectral character and yet differ from surrounding objects in high-resolution remote sensing imagery. Thereby, a new concept of Distinctive Feature of fractal is put forward and used in deriving Distinctive Feature curve of fractal evolution in multiscale segmentation. Through distinguishing the extremum condition of Distinctive Feature curve and the inclusion relationship of fractals in multiscale representation the Scalar Order is built. This can help to determinate the optimum scale in image segmentation for simple-objects, and the potential meaningful image-object fitting the intrinsic scale of the dominant landscape object can be obtained. Based on the application in high-resolution remote sensing imagery in coastal areas, a satisfactory result was acquired.

明代山东海防工程述论

从明朝初年开始,倭寇频频大规模侵扰我国,使沿海地区深受其害。为了抵御倭寇侵扰,明政府在山东沿海陆续设立11个卫、6个守御千户所,并建设了府城、县城、卫城、所城、军寨、墩堡等海防工程,形成了以卫所城池为主体的、防止倭寇入侵和海盗骚扰的完整而严密的海防工程体系。这些海防工程在当时适应了抗倭斗争的需要,是明代山东海防体系的重要基础、重要依托,对抵御倭寇侵扰起到了十分重要的作用。

不同影像处理方法在大坝施工范围识别中的应用分析

【目的】施工范围是大坝建设过程中施工精细化管理的基础内容,传统的施工范围识别方法主要是人工解译,效率低、成本高、主观性强。将影像智能解译的新方法应用于大坝施工范围识别成为一项有挑战性的技术问题。【方法】以我国贵州省凤山水库为研究区,通过对大坝施工范围特点与现有常用的遥感影像解译方法的分析,针对大坝施工范围具有的区域面积大且连续、地物复杂、人工扰动性程度高等特征,选用高分二号和哨兵二号遥感影像,研究不同的遥感影像解译方法在大坝施工范围自动识别的应用效果。【结果】文中用到的三种方法均取得较好的结果,且分别具有不同的优势。【结论】结果表明,基于影像分割的施工范围识别方法、基于变化检测的施工范围识别方法和基于影像智能分类的施工范围识别方法均能取得较好的识别结果,其中第二种方法最优,且无需人工干预;第三种方法次之,但是方法二和方法三对样本的数量和质量依赖性较高,且存在离散图斑错分的现象;第一种方法容易受阈值的选择和叠加分析的影响,识别精度低于后两种,但是处理流程简单、容易实现。

沿海地区超高层不规则底板抗浮锚杆施工技术研究

为解决沿海地区超高层地下工程中抗浮锚杆在不规则底板中的应用问题,论文以实际工程为研究对象,将实际施工需求与工程案例相结合,详细叙述了沿海地区超高层不规则底板抗浮锚杆的锚杆设计、制作、实验、施工顺序等施工工艺,并指出通过科学的设计优化和合理的施工管理,可以有效把控抗浮锚杆施工的全过程,减少现场结构技术问题及其他不确定性因素。

临江滨海强透水环境建筑工程载水减浮关键技术研究

结构抗浮设计是确保临江滨海强透水环境建筑工程安全的关键。依托广州某临江建筑工程,提出“载水减浮”概念。载水减浮新技术借助疏水、泄水等手段自主控制水位自溢泄流、均匀泄压,消除部分水浮力,充分利用有利荷载抵抗超出部分水浮力。搭建集地下水疏导、排泄、观测等多功能于一体的载水减浮系统。详细介绍载水减浮技术的施工步骤、要点、需妥善处理的问题及运维要求等。结果表明,载水减浮新技术具有成本低、工期短、环境影响小、施工便利等显著优势;解决了传统抗浮技术运用于临江滨海强透水环境建筑工程造价高、工期长、耐久性差的难题,最大程度实现依靠结构自身抵抗地下水浮力的目标,达到经济和安全的平衡。该抗浮新技术经验证后可推广至后续类似临江滨海强透水环境建筑工程的设计中。

滨海地区土岩复合地层城市轨道交通车站深大基坑施工稳定性分析

[目的]基坑开挖会引起周围地层和建(构)筑物产生变形,轻则影响施工进度,重则造成工程事故。为了保证城市轨道交通车站深大基坑的稳定性和安全性,需对基坑开挖过程中土层与围护结构的受力和变形特性进行研究。[方法]以青岛某地铁车站深大基坑为工程背景,结合土岩复合地层特性,采用数值模拟方法对深大基坑各施工工况下的变形及内力进行分析。结合现场数据,研究土岩复合地层下深大基坑开挖过程中地面沉降、围护桩位移及支撑轴力的变形规律。[结果及结论]数值模拟表明:未施工双轴高压旋喷桩时,端头井东墙、西墙及南墙均发生侧向位移,且侧向位移方向均朝向基坑内部,最大侧向位移为2.19 mm,发生在南墙中部;施工双轴高压旋喷桩时,基坑端头井一侧旋喷桩加固过程中,端头井侧墙变形量出现峰值,最大变形量为2.21 mm。未施工双轴高压旋喷桩时,地连墙内力变化峰值出现在其腰部,最大值为101 kN;施工双轴高压旋喷桩时,端头井旋喷桩加固地层侧的地连墙结构内力变化明显,其内力变化峰值出现在地连墙腰部,最大值为96 kN。由此可见,双轴高压旋喷桩对基坑各施工工况下的地连墙的内力有一定的减小作用,但对基坑变形影响不大。

基于Landsat影像的雄安新区2013−2021年土地利用变化检测和生态政策评估

利用2013−2021年共9期Landsat8影像,采用面向对象的监督分类方法,得到新区逐年土地利用与覆盖分类结果,进行LUCC分析及生态品质评价.结论:1)分类结果总体精度>86.8%,K为0.81~0.88,优于同期FROM-GLC及GLC_FCS全球分类产品;2)雄安新区设立至今耕地面积减少,不透水面和林地面积增长,蓝绿空间面积占比由12%增加至30%,雄安3县(雄县、容城县和安新县)建设严格遵循了新区《规划纲要》中植树造林、城市发展、湿地涵养3项不同的建设任务,各县主要土地利用覆盖变化分别为耕地向林地的转变、耕地与不透水面的相互转变以及耕地向水体和水生植被的转变;3)不透水面扩张与城市建设对生态品质的负面影响正逐步被森林覆盖率、蓝绿空间面积增加带来的正面影响所抵消.总体看,雄安新区土地利用/覆盖变化遵循新区规划要求,体现了经济社会发展和生态建设的成果.

冲孔灌注桩+工法桩组合支护体系在沿海深基坑工程中的应用

文中以福建沿海地区某工程为依托,对沿海深基坑中冲孔灌注桩+工法桩组合支护体系的施工技术深入探析。实践表明,基坑周边的位移变形量均满足设计值,支护结构自身变形及坑体位移控制方面均取得了良好效果。此外,施工完成28 d后,对冲孔灌注桩进行钻芯取样,其强度达到1.8 MPa,且观察到冲孔灌注桩及工法桩桩身完整,无渗水现象。

沿海围垦区钻孔灌注桩施工出现的问题及防治措施

围垦吹填工程常常涉及厚度不均、低承载力的高压缩性海积淤泥和淤泥质粉质黏土,这些条件给超长钻孔灌注桩的施工、成桩质量和单桩承载力带来了挑战。本文通过具体案例分析,研究了沿海围垦区钻孔灌注桩施工过程中所遇问题,并在此基础上提出了针对性的防治措施。这些建议旨在为业界同仁提供有益的参考和借鉴。

基于遥感技术的矿区地形测绘与变化监测

矿产资源开采是推动社会经济、科技发展的主要途径,而开采工作前需要做好矿区的地形测绘工作,开采过程中也需全程监测,确保开采顺利、安全地进行。然而,在矿山建设、开采工作等环节经常出现安全隐患,如果缺少对风险的管控,很会导致安全事故并制约矿山的开发和利用。虽然部分矿山企业十分注重矿山建设、开采环节的测绘和变化监测工作,但因测绘技术水平有待提升,很多变化现象无法直观体现,大大增加了建设、开采的难度,也易带来安全隐患。而遥感技术,不同于以往的测绘技术,能够全面测绘矿山区域并监测其变化,加之测绘的精度、有效性较高,可很好地满足矿山建设与开采的需要。在此背景下,科学应用遥感技术,结合矿山实际情况落实测绘方案,有助于矿山建设顺利、高效地进行。

西南山区公路施工期土地利用遥感监测研究

为实现对西南山区公路建设期土地利用的监测,获取公路施工区域周边土地利用变化情况,本研究以多时相卫星遥感影像为数据源,选取云南某高速公路施工区为研究区域,通过分析研究区公路施工前期、中期和后期的施工区域遥感影像数据,获取公路施工期土地利用变化情况。研究发现,利用遥感技术可较好地获取山区公路施工期土地利用的变化情况,可满足公路施工期间土地保护的环境监测要求。

Iterative construction of low-altitude UAV air route network in urban areas:Case planning and assessment

With the rapid increase of Unmanned Aircraft Vehicle(UAV) numbers,the contradiction between extensive flight demands and limited low-altitude airspace resources has become increasingly prominent.To ensure the safety and efficiency of low-altitude UAV operations,the low-altitude UAV public air route creatively proposed by the Chinese Academy of Sciences(CAS) and supported by the Civil Aviation Administration of China(CAAC) has been gradually recognized.However,present planning research on UAV low-altitude air route is not enough to explore how to use the ground transportation infrastructure,how to closely combine the surface pattern characteristics,and how to form the mechanism of "network".Based on the solution proposed in the early stage and related researches,this paper further deepens the exploration of the low-altitude public air route network and the implementation of key technologies and steps with an actual case study in Tianjin,China.Firstly,a path-planning environment consisting of favorable spaces,obstacle spaces,and mobile communication spaces for UAV flights was pre-constructed.Subsequently,air routes were planned by using the conflict detection and path re-planning algorithm.Our study also assessed the network by computing the population exposure risk index(PERI) and found that the index value was greatly reduced after the construction of the network,indicating that the network can effectively reduce the operational risk.In this study,a low-altitude UAV air route network in an actual region was constructed using multidisciplinary approaches such as remote sensing,geographic information,aviation,and transportation;it indirectly verified the rationality of the outcomes.This can provide practical solutions to low-altitude traffic problems in urban areas.

Spatiotemporal dynamics of impervious surface areas across China during the early 21st century

China has experienced an unprecedented urbanization and industrialization in the past decades. In this research, we examined the dynamics of construction lands and impervious surface areas (ISA) based on land use/cover change and ISA datasets between 2000 and 2008, which were provided by the national resources and environmental remote sensing information platform. The results indicated that the construction areas and ISA increased by 3468.30 and 2212.24 km 2 /a in this period primarily due to the implementation of national macro-development strategies and fast-growing economy. In 2008, ISA accounted for 0.86% of the total land area in China. Urban land areas increased by 43.46% between 2000 and 2008. The annual growth rate of 1788.22 km 2 /a in this period was 2.18 times that in the 1990s. In particular, urban ISA increased by 53.30% between 2000 and 2008 with an annual growth rate of 1348.85 km 2 /a. During the 8 years, the ISA in China increased rapidly, especially in the Beijing-Tianjin-Tangshan Metropolitan Region, Pearl River Delta, Yangtze River Delta, and the western China region. The increasing ISA may influence potentially water environmental quality in the major basins. In particular, the number of subbasins having ISA of greater than 10% increased considerably, which were primarily distributed in the Haihe River, Yangtze River and Pearl River basins. In 2008, 14.42% of the basin areas were affected by the increased ISA.

深圳滨海地区超长深基坑监测实例分析

文章以深圳滨海大道改造工程下沉隧道基坑为研究背景,通过监测围护墙体侧移、立柱竖向位移、地表沉降和支撑受力,开展关于滨海地区超长深基坑施工力学效应研究,分析总结基坑受力和变形规律。研究表明:截至2022年12月13日,基坑全线基本开挖完毕,最大开挖深度为35 m,实测数据显示墙体侧移,地表沉降、支撑轴力和立柱沉降累计增量均小于设计容许值,基坑整体安全可控,研究成果可为超长深基坑开挖施工提供有益的借鉴。

滨海地区桩墙咬合支护结构施工关键技术

针对滨海地区基坑支护结构的施工过程复杂、施工周期长及防水防渗要求高等问题,创新性地提出了桩墙咬合联合支护结构,其同时具备地下连续墙与圆形灌注桩的优点。采用榫结构对桩墙结构进行咬合连接,增强了桩墙结构咬合支护体系的整体性。通过总结铣槽施工及钢筋笼垂直度控制的施工工艺,形成新型桩墙咬合支护结构施工关键技术,支护结构可满足滨海地区基坑支护结构刚度大、止水效果好的需求。

临海抛石区嵌岩咬合桩的分层施工

针对深层含大块片石或抛石临海区域的桩基施工需求,在原有工程咬合桩施工工艺的基础上,通过对工艺、器具等进行研究、改进,结合临海实际工程地质的特殊性,总结了相应的施工技术。该技术操作方便、灵活多变,解决了临海抛石地区复杂地质条件下嵌岩咬合桩的施工难题,并在造价、环境保护、施工进度等方面具有一定优势,可以在以后类似的工程中进行推广应用。

热带沿海GRE管道施工管理要点

文章以马石油Petronas ASRS仓库项目的 GRE管道施工为基础,对到货仓储、施工、成品保护所遇到的问题进行了总结与思考。文章结合马来西亚当地的气候条件(热带沿海气候)、施工执行标准、当地施工队伍水平,对热带沿海地区施工出现的典型问题给出了解决方法及预防措施。