A novel method for approximating intercity networks:An empirical comparison for validating the city networks in two Chinese city-regions   总被引：8，自引：1，他引：7  

Miaoxi ZHAO  Kang WU  Xingjian LIU  Derudder BEN 《地理学报(英文版)》2015,25(3):337-354

A network perspective has increasingly become an organizational paradigm for understanding regional spatial structures. Based on a critical overview of existing empirical models for estimating intercity networks based on firm linkages, this study extends the recently proposed regional corporate city model algorithm by proposing a new method for approximating urban networks based on the locational strategies of firms. The new method considers both regional and hierarchical network features and avoids the information loss associated with the conversion from two-mode firm-city networks to one-mode city-city networks. In addition, networks estimated by using the method proposed herein are suitable when employing social network analysis. Finally, this method is empirically validated by examining intercity firm networks formed by advanced producer services firms in China’s two largest metropolitan areas, namely the Yangtze River Delta and Pearl River Delta. The presented empirical analysis suggests two main findings. First, in contrast to conventional methods (e.g., the interlocking city network model), our new method produces regional and hierarchical urban networks that more closely resemble reality. Second, the new method allows us to use social network analysis to assess betweenness and closeness centralities. However, regardless of the model applied, the validity of any method that measures urban networks depends on the soundness of its underlying assumptions about how network actors (firms, in our case) interact.  相似文献   

全球六边形离散格网的几何最优化设计与空间度量     

童晓冲  贲进  谢金华  韩硕 《地球信息科学学报》2015,17(7):774-782

全球离散格网系统（Discrete Global Grid System,DGGS）是一种新型的空间数据模型。它采用特定的方法进行地球表面的同构离散化,提供了一种无缝无叠的多尺度的全球格网结构。DGGS使用格网的地址编码运算代替传统的坐标计算来处理各种空间操作。本文以六边形DGGS为研究对象,提出了一种用于评价格网几何均匀性的新型最优化目标函数,设计了以启发式全局优化方法为核心,结合数值投影变换方法,构建六边形的DGGS。另外,针对DGGS目前的短板问题——空间度量,研究了DGGS上基于格网方法的面积度量、长度度量和角度度量,旨在发展一套全球六边形离散格网上的空间度量体系。  相似文献   

正八面体的六边形离散格网系统生成算法     

贲进  童晓冲  周成虎  张凯欣 《地球信息科学学报》2015,17(7):789-797

全球离散格网系统是一种面向全球的新型多分辨率数据建模与表达解决方案。与三角形和四边形格网相比,六边形格网具有对称性好、采样效率高、一致相邻等特点,更利于地球空间信息的建模、整合与分析。本文提出一种能生成各种六边形格网系统的算法,将正八面体上的相邻三角面组合为“四边形逻辑结构”,建立三轴离散斜坐标系,描述不同六边形剖分产生的多分辨率格网。其采用面向对象的思想设计了软件模型,通过实验验证了算法的可行性,分析了算法的效率。结果表明,该算法采用统一的数学模型描述正八面体上各种类型六边形剖分产生的离散格网系统,对应的软件模型,将不同格网系统的共性特征和个性特征分离,便于维护和扩展,具有一定的灵活性。  相似文献   

基于无人直升机平台的航磁系统集成与应用     

西永在  路宁  张兰  李军峰  张富明  吴珊  廖桂香  贲放  黄威 《物探与化探》2019,(1):125-131

笔者介绍了无人直升机航磁系统的研发与集成,采用无人直升机作为飞行平台,搭载高精度航空磁测系统,具有低成本、高效率、不受机场跑道限制、可夜航、按设计测线全自主导航飞行等特点。该系统分别完成了磁补偿试验飞行与实际应用工作,补偿精度达到0.046 9 n T,测量成果与测区内以往航磁成果对比,其反映的地磁场特征形态基本一致,验证了该系统的有效性,航磁异常等值线在细节上表现更细致。本系统为大比例尺、高精度、小面积的航磁测量工作提供了一种高效灵活的工作手段。  相似文献   

利用Mathematica实现共线条件方程自动线性化的教学实践     

贲进  杨春宇 《测绘通报》2017,(1):157-160

中心投影构像方程通常称为共线条件方程,它是摄影测量学的理论基石。共线条件方程线性化是建立摄影测量平差数学模型的前提,对初学者掌握解析空中三角测量的基本原理具有重要意义。针对专业课教学中人工线性化工作量大、容易出错、枯燥乏味等不足,本文采用Mathematica科学计算软件设计了计算机自动线性化方案。实践表明,该方案具有简便、准确、灵活等特点,能帮助初学者迅速掌握线性化技巧,教学效果良好。提出的思路和方法为提升专业课教学质量、促进教学改革探索了有效途径。  相似文献   

一种通用球面等积离散网格生成算法   总被引：5，自引：0，他引：5  

贲进  童晓冲张衡 李勇 《测绘学院学报》2005,22(4):252-255,258

球面离散网格模型是管理海量数据的有效途径,如何构建球面网格是这类模型的基础问题.文中利用Snyder等积多面体投影建立了平面与球面的对应关系,设计了球面等积三角形和四边形离散网格的生成算法.结合实验分析了两种网格的最大/最小边长比和单元周长均方差两项指标,结果表明全部网格的指标均收敛,适合用作多分辨率地理空间信息的管理.  相似文献   

关于立体集约生态用海的案例借鉴与制度探索          下载免费PDF全文

何方  黎思恒  唐晓  贲放  寻卓礼  姚炎明  杨一群  叶观琼 《海洋开发与管理》2022,39(7):113-118

随着海洋经济的发展,海域资源的开发从单一立体开发逐渐向多层立体开发转变,且开发的力度和密度不断加大,海洋生态环境面临着巨大压力。为缓解当前用海紧张与生态环境保护之间的矛盾,提高海域利用综合效益,亟须探索符合生态化、集约化、立体化和现代化的用海模式。在此背景下,“立体集约生态用海”的概念应运而生。文章通过列举国内外立体集约生态用海的典型案例,总结归纳其用海特点,对其未来的应用进行讨论。立体集约生态用海的出现将带来海域管理制度体系一系列的调整与改革,对中国未来走出一条海洋空间高质量发展与高水平保护的协同道路具有重要意义。  相似文献   

Contrasting P-T Paths in the Eastern Himalaya, Nepal: Inverted Isograds in a Paired Metamorphic Mountain Belt   总被引：1，自引：0，他引：1  

GOSCOMBE  BEN; HAND  MARTIN 《Journal of Petrology》2000,41(12):1673-1719

Petrology and phase equilibria of rocks from two profiles inEastern Nepal from the Lesser Himalayan Sequences, across theMain Central Thrust Zone and into the Greater Himalayan Sequencesreveal a Paired Metamorphic Mountain Belt (PMMB) composed oftwo thrust-bound metamorphic terranes of contrasting metamorphicstyle. At the higher structural level, the Greater HimalayanSequences experienced high-T/moderate-P metamorphism, with ananticlockwise P–T path. Low-P inclusion assemblages ofquartz + hercynitic spinel + sillimanite have been overgrownby peak metamorphic garnet + cordierite + sillimanite assemblagesthat equilibrated at 837 ± 59°C and 6·7 ±1·0 kbar. Matrix minerals are overprinted by numerousmetamorphic reaction textures that document isobaric coolingand re-equilibrated samples preserve evidence of cooling to600 ± 45°C at 5·7 ±1·1 kbar.Below the Main Central Thrust, the Lesser Himalayan Sequencesare a continuous (though inverted) Barrovian sequence of high-P/moderate-Tmetamorphic rocks. Metamorphic zones upwards from the loweststructural levels in the south are: Zone A: albite + chlorite + muscovite ± biotite; Zone B: albite + chlorite + muscovite + biotite + garnet; Zone C: albite + muscovite + biotite + garnet ± chlorite; Zone D: oligoclase + muscovite + biotite + garnet ± kyanite; Zone E: oligoclase + muscovite + biotite + garnet + staurolite+ kyanite; Zone F: bytownite + biotite + garnet + K-feldspar + kyanite± muscovite; Zone G: bytownite + biotite + garnet + K-feldspar + sillimanite+ melt ± kyanite. The Lesser Himalayan Sequences show evidence for a clockwiseP–T path. Peak-P conditions from mineral cores average10·0 ± 1·2 kbar and 557 ± 39°C,and peak-metamorphic conditions from rims average 8·8± 1·1 kbar and 609 ± 42°C in ZonesD–F. Matrix assemblages are overprinted by decompressionreaction textures, and in Zones F and G progress into the sillimanitefield. The two terranes were brought into juxtaposition duringformation of sillimanite–biotite ± gedrite foliationseams (S₃) formed at conditions of 674 ± 33°C and5·7 ± 1·1 kbar. The contrasting averagegeothermal gradients and P–T paths of these two metamorphicterranes suggest they make up a PMMB. The upper-plate positionof the Greater Himalayan Sequences produced an anticlockwiseP–T path, with the high average geothermal gradient beingpossibly due to high radiogenic element content in this terrane.In contrast, the lower-plate Lesser Himalayan Sequences weredeeply buried, metamorphosed in a clockwise P–T path anddisplay inverted isograds as a result of progressive ductileoverthrusting of the hot Greater Himalayan Sequences duringprograde metamorphism. KEY WORDS: thermobarometry; P–T paths; Himalaya; metamorphism; inverted isograds; paired metamorphic belts  相似文献   

电磁勘探中各向异性研究现状和展望   总被引：2，自引：1，他引：1       下载免费PDF全文

刘云鹤  殷长春  蔡晶  黄威  贲放  张博  齐彦福  邱长凯  任秀艳  黄鑫  曹晓月  孙思源 《地球物理学报》2018,61(8):3468-3487

电各向异性广泛存在于自然界中,已成为电磁勘探资料解释中不可忽视的因素.特别是在一些沉积岩地区,由于层理发育导致地下介质电阻率随电流方向发生变化,表现出很强的各向异性导电性.此时,利用各向同性模型进行电磁数据解释将引起很大的误差.本文回顾了电磁勘探中电各向异性研究的历史,简要介绍电各向异性成因、数值模拟中的数学描述及电各向异性介质中电磁场正反演模拟方法等研究现状,总结电各向异性在大地电磁、可控源电磁、航空电磁和感应测井等方面的最新研究进展及未来的挑战.随着多维电磁数据采集及正反演模拟技术的进步和计算能力的提高,给电各向异性信息提取和应用带来了新的契机.电各向异性研究将在矿产资源勘查、油气存储与运移特征分析、地下水和地热、环境工程地质调查、大地构造及地质灾害预测等方面发挥积极作用.  相似文献