一种可扩展的线性可排序四叉树空间索引     

胡晨希  刘会侠  乐鹏  王艳东 《测绘信息与工程》2010,35(5):1-3

分析了四叉树空间索引的优缺点,提出了一种可扩展的线性可排序四叉树空间索引,实现了空间索引的动态更新,同时具有高效的空间查询能力。  相似文献   

浅论自发地理信息的数据管理   总被引：5，自引：0，他引：5  

李德仁  钱新林 《武汉大学学报(信息科学版)》2010,(4)

分析了自发地理信息(volunteered geographic information,VGI)数据的来源、分类、特点与管理要求,探讨了VGI数据清理与质量控制,研究了以高效处理绘图查询与数据更新为目标的VGI图形数据管理问题,提出了动态线综合二叉树与缩放四叉树的设计思想,以解决VGI图形数据管理中的难点问题。  相似文献   

自适应卡尔曼滤波在GPS/DR组合导航中的应用     

陈远  张小红  郭斐  熊旭  李海英 《测绘科学》2010,35(3):169-170,155

针对在观测条件较差的情况下卡尔曼滤波的鲁棒性较差,本文设计了一种自适应卡尔曼滤波模型。通过实际车载GPS/DR组合导航试验,结果表明该模型在观测质量较差的情况下能够抑制较大的偏差,相对于标准卡尔曼滤波模型,其平面定位精度提高了近一倍,达到2～3m。因此,在观测环境较差的情况下建议采用渐消自适应卡尔曼滤波模式进行组合导航。  相似文献   

车载激光点云的道路标线提取及语义关联     

姚连璧  秦长才  张邵华  陈启超  阮东旭  聂顺根 《测绘学报》2020,49(4):480-488

自动驾驶技术已成为未来智能交通的发展方向之一,高精度地图为L3级及以上自动驾驶实现高精度定位和路径规划提供先验信息,是自动驾驶车辆传感器在遮挡或观测距离受限情况下的重要补充。道路标线的位置和语义信息,比如实线和虚线的绝对位置是高精度地图的基本组成部分。本文从车载激光点云中提取扫描线,根据道路边缘位置几何形态的突变从扫描线中提取道路路面,在此基础上首先利用反距离加权插值的方法把路面点云图像以一定的分辨率转换为栅格图像,其次利用基于积分图的自适应阈值分割方法把栅格图像转化为二值图像,然后利用欧氏聚类的方法从二值图像中提取标线点云,并利用特征属性筛选的方法对提取的标线点云进行语义识别,最后建立交通标线和交通规则之间的语义关联。  相似文献   

非典型周期和气候突变的识别与判定     

秦建国 《水文》2020,40(1):23-28

通过两种新方法分析了无锡站降水年际变化的突变性、周期性等特征,揭示了旱涝演化的自然规律。研究表明,1934、1978、2013年是我国近现代气候突变的临界点,这是旱涝演化的自然选择;无锡站年际降水的观测历史可分成四个特征不同的时段,每个时段节点对应的都是一次气候突变;气候突变会改变年际降水序列的一致性,分段法研究可以大幅度降低模拟难度、提高预测效率。发现并确认了3个气候突变点,实现了超长缺测中断期(13a)旱涝趋势的精确插补,完成了无锡站近百年降雨序列的周期性分析与旱涝趋势预测模拟,研究成果改变了近现代气候历史无法细分的现状。  相似文献   

Decadal link between longitudinal morphological changes in branching channels of Yangtze estuary and movement of the offshore depo-center     

Boyuan Zhu  Yao Yue  Alistair G.L. Borthwick  Wenjun Yu  Enhang Liang  Jinwu Tang  Yuanfang Chai  Yitian Li 《地球表面变化过程与地形》2020,45(11):2689-2705

In estuaries, the morphology of inland and offshore areas usually evolves synergistically. This study examines the decadal link between longitudinal changes in morphology of branching channels and movement of the offshore depo-center (where sediment deposition rate is maximum) of the Yangtze River estuary, under intense human interference. Integrated data analysis is provided on morphology, runoff discharge, and ebb partition ratio from 1950 to 2017. Channel-volume reductions and change rates between isobaths in branching channels reflect the impact of estuarine engineering projects. Ebb partition ratio and duration of discharge ≥ 60 000 m³ s^-1 act as proxies for the water excavating force in branching channels and runoff intensity. It is found that deposition occurs in the lower/upper sub-reaches (or further downstream/upstream channels) of the inland north/south branching channels, and the offshore depo-center moves southward or southeastward, as runoff intensity grows; the reverse occurs as runoff intensity declines. This is because the horizontal circumfluence in the Yangtze estuary rotates clockwise as ebb partition ratios of the north/south branching channels increase/decrease for increasing runoff, and conversely rotates anticlockwise for decreasing runoff. Land reclamation activities, the Deepwater Channel Project, and the Qingcaosha Reservoir have impacted greatly on longitudinal changes of morphology in the North Branch and the South Passage and on ebb partition ratio variations in the North/South Channel and the North/South Passage. Dam-induced runoff flattening has enhanced deposition in the upper/lower sub-reaches of the north/south branching channels and caused northward movement of the offshore depo-center, except in areas affected by estuarine engineering projects. Dam-induced longitudinal evolution of branching channel morphology and offshore depo-center movement will likely persist in the future, given the ongoing construction of large cascade dams in the upper Yangtze and the completion of major projects in the Yangtze estuary. © 2020 John Wiley & Sons, Ltd.  相似文献   

Improving sustainability of urban drainage systems for climate change adaptation using best management practices: a case study of Tehran,Iran     

Negin Binesh  Amin Sarang  Wolfgang Rauch 《水文科学杂志》2019,64(4):381-404

Although the effectiveness of best management practices (BMPs) in reducing urban flooding is widely recognized, the improved sustainability achieved by implementing BMPs in upstream suburban areas, reducing downstream urban floods, is still debated. This study introduces a new definition of urban drainage system (UDS) sustainability, focusing on BMP usage to enhance system performance after adaptation to climate change. Three types of hydraulic reliability index (HRI) plus robustness and improvability indices were used to quantify the potential enhanced sustainability of the system in a changing climate, together with a climate change adaptability index (CCAI). The sustainability of UDS for the safe conveyance of storm-water runoff was investigated under different land-use scenarios: No BMP, BMP in urban areas, and BMP inside and upstream of urban areas, considering climate change impacts. Rainfall–runoff simulation alongside drainage network modelling was conducted using a storm-water management model (US EPA SWMM) to determine the inundation areas for both base-line and future climatic conditions. A new method for disaggregating daily rainfall to hourly, proposed to provide a finer resolution of input rainfall to SWMM, was applied to a semi-urbanized catchment whose upstream runoff from mountainous areas may contribute to the storm-water runoff in downstream urban parts. Our findings confirm an increase in the number of inundation points and reduction in sustainability indices of UDS due to climate change. The results present an increase in UDS reliability from 4% to 16% and improvements in other sustainability indicators using BMPs in upstream suburban areas compared to implementing them in urban areas.  相似文献   

基于多元自回归样条的液化侧移灾害评估模型          下载免费PDF全文

李程程  李兆焱  袁晓铭 《地震工程学报》2019,41(5):1355-1360

为了将液化侧移计算方法本土化,本文基于Youd等人收集的液化侧移数据库,采用擅长处理复杂参数维度问题的多元自适应样条回归法（MARS）建立液化侧移计算模型。经验证,该方法建立的模型精度和可靠性都可以通过检验。本文主要内容包括：（1）在本土化过程中,本文选取峰值加速度PGA作为地震动参数,替代现有模型中的M和R,计算结果并未影响液化侧移计算精度;（2）在MARS方法进行建模过程中,对临空和缓坡两种情况的影响因素进行重要性程度计算和筛选;（3）建立两种情况下的液化侧移计算模型,并用F检验法和t检验以及新西兰2010—2011年系列地震中液化侧移数据进行检验,证明本文方法的合理性和可靠性。本文的结果能满足我国相关规范、工程师以及岩土地震工程防灾减灾等方面的需求,还可为地震液化侧移灾害小区划提供理论基础。  相似文献   

自适应锚索锚固岩质边坡地震动力响应分析     

许明  唐亚锋  刘先珊  罗斌  唐道勇 《岩土力学》2018,39(7):2379-2386

强震作用下常规锚索往往会因材料变形能力不足导致应力过载而被拉断,一旦锚索失效将直接危及整个锚固结构的安全。为研究自适应锚索的动力响应规律以及在自适应锚索支护下锚固边坡的动力特性,以新型抗震锚索为原型,设计自适应锚索锚固岩质边坡试验模型,并利用振动台试验系统对试验模型进行加载。试验中采用正弦波、天津波、EI波以及Taft波等4种地震波进行研究,监测锚索的应变和边坡动力响应。结果表明：锚索的轴力和地震波幅值、类型、地震激励频率等因素密切相关;锚固边坡坡面加速度及位移沿边坡高程均有不同程度的放大,相对于无锚索支护边坡,锚固边坡坡面加速度和位移峰值均有减小;自适应锚索随着预设滑移恒阻力的不同,锚索会产生不滑移、瞬间滑移、逐步滑移3种工况,对应的锚索应变时程曲线和锚固边坡动力安全系数时程具有显著不同的特征;自适应锚索滑移工况下,滑体的安全系数虽然有局部减小的阶段,但是锚固结构的安全储备较大,可适应边坡大变形和瞬态冲击荷载的作用。试验结果可为强震区路堑边坡的支护和自适应锚索抗震设计提供一定参考。  相似文献   

基于环形扫面测量的三维直流电阻率法任意各向异性模型响应特征     

殷长春  杨志龙  刘云鹤  张博  齐彦福  曹晓月  邱长凯  蔡晶 《吉林大学学报(地球科学版)》2018,48(3):872-880

高精度地下任意各向异性介质电性分布特征识别是当前的热门研究课题。本文以国内外前人工作为基础,基于非结构化网格,利用基于梯度恢复的后验误差估计指导网格自适应细化过程,实现了直流电阻率法三维有限元数值模拟。通过与一维模型半解析解的对比,验证了本文算法的有效性。考虑到电各向异性介质在观测中存在视电阻率反常现象,本文采用了环形扫面测量方法。通过对几种典型各向异性模型的模拟分析,得到了相应的各向异性影响规律和识别特征,各向异性主轴电阻率之间的比值大小决定了椭圆型视电阻率极性曲线长轴与短轴的比值大小,主轴电阻率的旋转方向会改变视电阻率极性曲线的形状。本文的算法研究及数值模拟技术可为直流电法数据精细处理和解释提供技术支撑。  相似文献