道路网增量更新中拓扑冲突的检测方法     

周明辉  翟仁健 《测绘科学技术学报》2017,34(3)

为提高空间数据增量更新中拓扑冲突的检测效率,针对道路网数据,首先分析了增量要素进行更新时可能产生的拓扑冲突的类型和特点,运用规则格网进行邻近区域的表达;然后使用5元组模型描述增量要素与邻近区域要素间的拓扑关系,与设定的拓扑冲突表达进行比较,判断是否存在拓扑冲突。实验结果表明,本方法对于道路网数据增量更新中的拓扑冲突的类型区分准确全面,检测效率较高,具有很好的实用性和可靠性。  相似文献   

A morphological investigation of marine transgression in estuaries     

Ian Townend  Zeng Zhou  Leicheng Guo  Giovanni Coco 《地球表面变化过程与地形》2021,46(3):626-641

The landscape setting of estuaries varies widely and is an important aspect of determining how they evolve. This paper focusses on alluvial estuaries in river valleys and how they respond to sea level rise. We examine the implications of marine transgression, as a response to sea level rise, where the estuary moves upwards and landwards to maintain its position in the tidal frame (so-called stratigraphic rollover). Here we encapsulate such kinematic movement of the estuary morphology using a ‘morphokinematic’ model, to assess the potential response to sea level rise and sediment supply. The model of the estuary form includes a single convergent channel, intertidal and surrounding floodplains (the valley) and allows the relative importance of the space available for deposition of sediments, the accommodation space, to be investigated as a function of rates of sea level rise and sediment supply. The transgression of the system is determined using a sediment mass balance, taking account of any supply from the river and marine environment. Model results confirm that the transgression distance, measured as the distance the entity moves landward, varies in proportion to the change in accommodation space, which mainly depends on the floodplain area. As the size of the floodplain reduces, the transgression distance is less and the system becomes much more sensitive to changes in the rate of sea level rise or changes in sediment supply. The greater demand for sediment when a floodplain is present results in greater cannibalization of the estuary form (i.e. greater landward movement) to meet the sediment demand. When the floodplain is disconnected from the estuary, the synergistic relationship is lost and the accommodation space increases. The capacity for restoration will depend on the availability of sediment and the prevailing rate of sea level rise.  相似文献   

改进的贝叶斯迭代反演方法及其在白云岩致密储层识别的应用     

马琦琦  孙赞东  杨柳鑫 《物探与化探》2019,(2):234-243

由于低孔隙度和低渗透率的白云岩致密油储集层的纵波阻抗与其围岩差异非常小,利用叠后反演技术难以有效预测储层,而可以提取丰富弹性信息的叠前反演是解决此问题的有效手段,但是由于噪声等问题,叠前反演方程有较强的不适定性,笔者在贝叶斯框架下引入了改进的多变量柯西分布和改进的低频约束因子,重新推导了反演方程,获得了新的目标函数,有效地减少了反演的不适定性,从而提高了反演的稳定性,并结合迭代的思想来不断更新反演求解过程中的背景纵横波速度比值,从而增加了反演结果的精度。模型数据测试和实际资料应用都证明了该方法的稳定性和适用性。统计表明,利用提出的反演方法,目的层段内优质储层厚度预测吻合率高达89.75%。因此,此方法对类似硅质致密储层的勘探有重要的借鉴意义。  相似文献   

对欧拉矢量附加不等式约束的RELSM模型及其应用     

范成成  张俊  雷前坤  武宇  黄康钰 《大地测量与地球动力学》2020,40(7):667-670

借鉴选权拟合思想,对区域地壳运动的整体旋转和线性应变模型中欧拉矢量部分附加不等式约束,将区域地壳运动的欧拉参数约束到由多年观测资料确定的平均欧拉参数值附近,建立附有不等式约束的整体旋转和线性应变模型。对中国大陆构造环境监测网络在环渤海区域的近几期GPS观测速度场数据进行拟合分析,结果表明,本文方法通过不等式约束可适当增强块体整体运动趋势的平滑性,获得对速度场更高的拟合精度,可进一步增强模型的物理解释能力。  相似文献   

复杂区域对象拓扑关系分解与计算     

王占刚  杜群乐  王想红 《测绘学报》2017,46(8):1047-1057

本文提出了基于9交矩阵的拓扑关系计算方法,将复杂区域分解有限个简单区域,采用正则表达式描述其多部分和洞构成,通过定义两个9交关系矩阵操作算子,利用分解区域间的拓扑关系直接计算复杂区域间的9交关系矩阵。详细证明和分析了两个操作算子的不成立条件以及消除不成立条件的方法。结合关系矩阵表法拓扑关系的推导和推理过程,操作算子可用于推导已知结构复杂区域间的所有可能9交拓扑关系。同时,9交关系矩阵操作算子依赖复杂区域的定义,不适用于所有区域对象。  相似文献   

一种融合空间拓扑关系的室内无线定位方法     

牛磊  莫帅  张观宝  宋宜全  李毅 《测绘科学》2017,42(5)

针对仅利用无线信号源和其发射信号强度定位会丢失待测位置与信号源之间固有空间关系的问题,提出了利用已知位置接收信号源发射的无线信号强度测量未知点的低成本室内定位方法。该方法深入分析了待定位点和无线信号源以及信号覆盖范围之间的空间关系,充分利用RCC-8空间关系模型进行无线定位。实验结果表明,采用这种融合空间拓扑关系的基于无线信号强度的室内定位方案能够优化定位流程,并在测得位置中反映待测点和信号源之间的相对空间关系。  相似文献   

环境约束下中国工业化与城镇化的关系演变——效率分析视角   总被引：4，自引：3，他引：1  

王庆喜  钱遂  庞尧 《地理科学》2017,37(1):92-101

将工业化视为投入,城镇化视为产出,基于中国各省份2001~2012年的工业化、城镇化和污染物排放数据,测算了传统效率值、环境效率值及效率指数,据此分析各省份工业化与城镇化的关系及其演变。研究发现：全国总体层面的城镇化传统效率值和环境效率值均在下降。分地区来看,东部地区通过工业化来推进城镇化的实施空间有限,中部地区需要调整发展方式,西部地区尚有一定余地。在城镇化过程中,工业化存在前期“负向规律机制”和后期“正向反馈机制”两种作用。为实现城镇化低碳发展,需要转变工业和经济发展方式,改善对外贸易结构,同时提高环境污染治理投资效果。  相似文献   

环境约束下中国城市土地利用效率演变特征分析     

施佳颖  何亚芬 《资源与生态学报(英文版)》2021,12(2):143-154

在经济高质量发展和区域协调发展的背景下,考虑非期望性产出(环境污染),本文利用SBM-undesirable模型测算了中国275个地级市2003–2016年的城市土地利用效率,并通过核密度估计、空间自相关分析探索了城市土地利用效率的时空演变规律。结果表明:(1)2003–2016年间,中国城市土地利用效率整体呈波动上升趋势,但仍处于较低水平,城市土地利用效率均值呈现东、西、中逐渐降低的分布格局;(2)在全国和东中西三大区域,区域差异均不断增大,全国尺度上和东部地区效率值出现了极化趋势;(3)城市土地利用效率呈现较弱的空间正相关,但空间集聚程度不断增强。高-高集聚型区域多分布在东南沿海地区,且不断向中部地区延伸;高-低极化型区域多为中西部地区的省会城市,低-高凹陷型区域零星分布于高值聚集区周边,部分在研究期内转为高值聚集区域;低-低均质型区域主要分布在中西部及东北地区。研究结果认为应加强对城市存量土地的内涵挖潜,强化区域合作机制,因地制宜制定提升土地利用效率的政策是促进城市土地集约节约利用和区域协调发展的有效路径。  相似文献   

The trade network of the Belt and Road Initiative and its topological relationship to the global trade network   总被引：2，自引：0，他引：2  

Zhouying Song  Shuyun Che  Yu Yang 《地理学报(英文版)》2018,28(9):1249-1262

Unimpeded trade is one of the cooperation priorities in the Belt and Road Initiative proposed by China. On 15 May 2017, the Joint Communique of the Leaders Roundtable of the Belt and Road Forum for International Cooperation reaffirmed the participants’ shared commitment to build an open economy and ensure free and inclusive trade. The Belt and Road Initiative (BRI) is not only China's new action to drive its open and global development, but also a platform for an increasing number of countries to explore free and inclusive trade and promote a universal, rule-based, open, non-discriminatory, and equitable multilateral trade system. It is therefore important to examine the topological relationship between the BRI and global trade networks. More specifically, this article first analyzes the community structure of trade networks using a community detection algorithm, and then estimates the topological relationship between different trade communities. The findings of this article are as follows. First, this research identified three trade communities and two sub-communities in the BRI trade network, in which China is the core, Russia is the sub-core of the biggest trade community, and India, United Arab Emirates, and Saudi Arabia are cores of the second trade community (South Asia-West Asia). Second, it identified five trade communities in the global trade network, centred on China, USA, Russia, India-United Arab Emirates, and Germany- Netherlands-France-Britain and other European developed countries. Third, the topological analysis indicated that in the global trade network, most BRI countries are attracted by the core nodes of the BRI regions, such as the China, Russia and India-United Arab Emirates core nodes, and have strong trade contacts with BRI countries. Most Central-East European countries are mainly attracted by Germany-Netherlands-France-Britain and other developed European countries with a low penetration of BRI trade. Although some Southeast Asian countries are incorporated into the Asia-Australia-South Africa community with China as the core, they still need to strengthen trade linkages with BRI countries.  相似文献   

基于Quanser实验平台的带有输出约束单连杆柔性机械臂的神经网络控制     

侯佳祎  高赫佳  贺威  孙长银 《南京气象学院学报》2018,10(6):695-705

机械臂在航空航天、服务等领域的应用越来越广泛,其研究也越来越深入.相比于刚性机械臂,柔性机械臂质量轻、能耗小,具有更好的性能.但是,由于柔性机械臂本身的结构与材料具有特殊性,其在运动过程中会产生弹性形变与振动,这就给机械臂的定位、轨迹跟踪带来了困难,因此对其振动抑制的研究具有重要意义.本文利用假设模态法对单连杆柔性机械臂系统进行建模,通过李雅普诺夫直接法实现了闭环系统的稳定性.由于一些实际问题对控制系统的状态量有特殊要求,因此采用正切函数形式的障碍李雅普诺夫策略来处理输出约束问题,之后利用神经网络控制方法来逼近系统的不确定性,通过李雅普诺夫法对闭环系统的稳定性进行了分析,并基于Matlab平台设计仿真、基于Quanser实验平台进行实验,对控制器的控制性能进行了验证.  相似文献