道路网增量更新中拓扑冲突的检测方法

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。     

Rutile inclusions in garnet from a dissolution‐reprecipitation mechanism

Metamorphic garnet commonly contains needle‐like rutile inclusions as well as equant rutile inclusions that surround quartz inclusions and range in size from submicrometer to nanometer. Although the origin of these equant rutile inclusions, that is, exsolution or non‐exsolution, has important implications for petrological and tectonic processes, the crystallographic characteristics of these inclusions have rarely been studied because of the small sizes and analytical difficulties involved. Here, we report the crystallographic characteristics pertinent to the genetic origin of minute equant rutile inclusions in cloudy, nearly spherically shaped garnet domains with Ti‐depleted compositions surrounding quartz inclusions in ultrahigh‐pressure garnet from several diamondiferous Erzgebirge quartzofeldspathic gneissic rock samples. TEM analyses show that the equant rutile crystals in cloudy garnet domains are partially bounded by the low‐energy {100}_rt ± {110}_rt ± {101}_rt facets and have rather random crystallographic orientation relationships (CORs) with the garnet host, with preferential alignment of low‐energy lattice planes, for example, {100}_rt//{112}_grt, for some rutile crystals. Although the rather random CORs are unlikely to be attributed to solid‐state exsolution subjected to the stringent topotactic garnet lattice constraints, the characteristic subhedral {100}_rt ± {110}_rt ± {101}_rt crystal forms of rutile can be rationalized by a metasomatic dissolution‐reprecipitation mechanism via a fluid phase. In this scenario, the quartz+fluid inclusions in garnet were first subjected to decompression microcracking during rock exhumation, followed by dissolution of Ti‐bearing garnet matrix at the crack tips or along the crack surfaces and subsequent reprecipitation of rutile, apatite, gahnite, akdalaite, and Ti‐depleted garnet. The rapid coalescence between rutile and garnet crystals in fluid or direct attachment of rutile crystals onto the dissolving crack surfaces would then yield the rather random CORs as reported here. These results, along with previous work on rutile needles, indicate rather diverse genesis of rutile inclusions in various crystal forms, thus shedding light on the controversial exsolution origin for other inclusion suite/microstructure in minerals.     

复杂区域对象拓扑关系分解与计算

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。     

一种融合空间拓扑关系的室内无线定位方法

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。     

The trade network of the Belt and Road Initiative and its topological relationship to the global trade network

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.     

Classifying natural-language spatial relation terms with random forest algorithm

The exponential growth of natural language text data in social media has contributed a rich data source for geographic information. However, incorporating such data source for GIS analysis faces tremendous challenges as existing GIS data tend to be geometry based while natural language text data tend to rely on natural language spatial relation (NLSR) terms. To alleviate this problem, one critical step is to translate geometric configurations into NLSR terms, but existing methods to date (e.g. mean value or decision tree algorithm) are insufficient to obtain a precise translation. This study addresses this issue by adopting the random forest (RF) algorithm to automatically learn a robust mapping model from a large number of samples and to evaluate the importance of each variable for each NLSR term. Because the semantic similarity of the collected terms reduces the classification accuracy, different grouping schemes of NLSR terms are used, with their influences on classification results being evaluated. The experiment results demonstrate that the learned model can accurately transform geometric configurations into NLSR terms, and that recognizing different groups of terms require different sets of variables. More importantly, the results of variable importance evaluation indicate that the importance of topology types determined by the 9-intersection model is weaker than metric variables in defining NLSR terms, which contrasts to the assertion of ‘topology matters, metric refines’ in existing studies.     

PHYSICO‐GEOCHEMICAL AND MINERAL COMPOSITION OF NEEM TREE SOILS AND RELATION TO ORGANIC PROPERTIES

The Neem tree, the oil of which has a long history of pesticide, fertilizer and medicinal use in India, has been studied extensively for its organic compounds. Here we present a physical, mineralogical and geochemical database resulting from the analyses of two Neem soil profiles (epipedons) in India. Neem tree derivatives are used in the manufacture of a variety of products, from anti‐bacterial drugs and insecticides to fertilizers and animal feeds. A preliminary geochemical and mineralogical analysis of Neem soils is made to explore the potential for chemical links between Neem tree derivatives and soils. Physical soil characteristics, including colour, texture and clay mineralogy, suggest the two pedons formed under different hydrological regimes, and hence, are products of different leaching environments, one well‐drained site, the other poorly drained. Geochemically, the two Neem soils exhibit similarities, with elevated concentrations of Th and rare earth elements. These elements are of interest because of their association with phosphates, especially monazite and apatite, and the potential link to fertilizer derivatives. Higher concentrations of trace elements in the soils may be linked to nutritional derivatives and to cell growth in the Neem tree.     

在图形简化中面状目标间拓扑关系渐进式转换的研究

拓扑关系是空间关系中最为重要的关系,在空间抽象中,拓扑关系会发生变化,如何控制这种变化?如何在更抽象的层次上维护空间拓扑关系的一致性,就是一个非常重要的问题。本文以拓扑关系成分抽象的转换方法为基础,研究了面之间拓扑关系的抽象规则,并详细探讨了这些拓扑关系的渐进式转换方法,绘制了相应的面之间基本拓扑关系渐进式转换图。     

面向自然连续面群边线的协同化简方法

自然连续面群边线化简是地形图中自然面状要素和地理国情普查数据中自然图斑自动制图综合的重要实施步骤。现有面要素边线化简算法大多以线化简算法为基础,未有效化简弯曲特征、保持面积平衡和满足图面视觉清晰性要求,且化简结果存在共享边界不一致、边线自相交和边线之间相交的拓扑问题。为此,结合自然连续面群表达特点和化简要求,本文提出一种面向自然连续面群边线的协同化简方法。首先将自然连续面群转换为拓扑数据结构组织,以待化简弧段及其相邻弧段为基础构建约束Delaunay三角网,标识化简区域;其次利用弧段双侧层次多叉树模型渐进式退化条带状弯曲、化简细小弯曲;最后自适应夸大狭窄“瓶颈”,实现边线的协同化简。以河南省某区域1:5万地形图中的植被与土质面要素进行化简实验,相较于对比方法,该方法能够有效保持自然连续面群边线化简前后的拓扑一致性、要素之间的面积平衡,充分化简目标尺度下的局部不清晰细节,化简结果精度高。     

Remarks on the Definition and Estimation of Friction Velocity

One of the mainscaling parameters in similarity theory of the atmospheric boundary layer is friction velocity. Unfortunately, several definitions of friction velocity exist in the literature. Some authors use the component of the horizontal Reynolds stress vector in the direction of the mean wind vector to define friction velocity. Others define the friction velocity by means of the absolute value of the horizontal Reynolds stress vector. The two definitions coincide only if the direction of the mean wind vector is parallel to the horizontal Reynolds stress vector. In general, the second definition gives larger values for the friction velocity. Over complex terrain the situation is further complicated by the fact that the terrain following flow is not necessarily horizontal. Thus, several authors have proposed to use terrain following coordinate systems for the definition of friction velocity. By means of a large dataset of fast-response wind measurements with an ultrasonic anemometer the friction velocities resulting from the different definitions are compared. Furthermore, it is shown that friction velocity can be well estimated from horizontal wind speed, and even better from simple horizontal or vertical turbulence parameters.