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| 1 | A 3D GIS spatial data model based on conformal geometric algebra显示文摘We propose a new Geographic Information System (GIS) three-dimensional (3D) data model based on conformal geometric algebra (CGA). In this approach, geographic objects of different dimensions are mapped to the corresponding basic elements (blades) in Clifford algebra, and the expressions of multi-dimensional objects are unified without losing their geometric meaning. Geometric and topologic computations are also processed in a clear and coordinates-free way. Under the CGA framework, basic geometrics are constructed and expressed by the inner and outer operators. This expression combined geometrics of different dimensions and metric relations. We present the structure of the framework, data structure design, and the data storage, editing and updating mechanisms of the proposed 3D GIS data model. 3D GIS geometric and topological analyses are performed by CGA metric, geometric and topological operators using an object-oriented approach. Demonstrations with 3D residence district data suggest that our 3D data model expresses effectively geometric objects in different dimensions, which supports computation of both geometric and topological relations. The clear and effective expression and computation structure has the potential to support complex 3D GIS analysis, and spatio-temporal analysis. | YUAN LinWang YU ZhaoYuan LUO Wen ZHOU LiangChen LU GuoNia | 2011 | Science China Earth Sciences2011，54，1： | 26 |
| 2 | ENSO signals and their spatial-temporal variation characteristics recorded by the sea-level changes in the northwest Pacific margin during 1965-2005显示文摘Sea-level is closely linked to the Earth's climate and its change is important as a metric for global and regional climate change. Identifying, extracting, and revealing such information through detailed analysis is the prerequisite for understanding the mechanisms of sea-level change. The monthlyaverage tide-change records reported and examined in this paper are from 10 tide gauge stations distributed in the northwest margin of the Pacific Ocean, registered during the period 1965-2005. In particular, we have utilized the Second Order Blind Identification (SOBI) method to identify and the Empirical Mode Decomposition (EMD) method to extract the El Nio-Southern Oscillation (ENSO) signals imprinted in those tide gauge records; and subsequently, we have investigated the spa-tial-temporal characteristics of the extracted ENSO signals using wavelet analysis methods. The following results are obtained: (1) the ENSO events recorded by each tide gauge series are of different types and intensity, which show considerable temporal-spatial variation characteristics, with sea-level responses to ENSO signals remarkably stronger in low latitude areas than in medium-high latitude areas; (2) due to the influences of ocean currents, topographical conditions, and other factors, there exist variations in the type of relationship between the sea-level changes and the recorded ENSO events at different latitudes; (3) sea-level changes can also denote scale-variation characteristics of ENSO events, and particularly, since 1980s, all the tide gauges located south of Kanmen show intense responses to ENSO and the timescale of ENSO events extended gradually from around 4 years to 2-8 years, reflecting variations in the intensity and frequency of ENSO events; and (4) reverse changes of certain scale were noted before and after strong ENSO events recorded by sea-level changes, supporting the research findings about the interaction (mutual coupling and superimposition) between the probability of occurrence of strong ENSO events and their time scale. | YUAN LinWang,YU ZhaoYuan,XIE ZhiRen,SONG ZhiYao & Lü GuoNian School of Geographical Science,Nanjing Normal University,Nanjing 210046,China | 2009 | Science China Earth Sciences2009，52，6： | 14 |
| 3 | Geometric algebra method for multidimensionally-unified GIS computation显示文摘Seamless multidimensional handling and coordinate-free characteristics of geometric algebra (GA) provide means to construct multidimensionally-unified GIS computation models. Using the multivector representation for basic geometric objects within GA, we are able to construct adaptable unified geometric-topological structural models of a multidimensional geographical scene. Multidimensional operators found within the geometry, topology and GIS analysis are developed with basic GA operators. A unified computational framework is proposed, it unifies expressions and operation structures, as well as supports the analysis of multidimensional complex scenes. Finally, we illustrate modelling a three-dimensional residential district, which shows that GAbased multidimensionally-unified computation models can effectively represent and analyze complex and multidimensional geographical scenes. The development of the proposed GIS multidimensionally-unified representation, analysis, and modeling enhances current GIS algorithms and geographical models. | YUAN LinWang LüGuoNian LUO Wen YU ZhaoYuan YI Lin SHENG YeHua | 2012 | Chinese Science Bulletin2012，57，7： | 13 |
| 4 | Geographic scenario:a possible foundation for further development of virtual geographic environments显示文摘It has been two decades since virtual geographic environments(VGEs)were initially proposed.While relevant theories and technologies are evolving,data organization models have always been the foundation of VGE development,and they require further exploration.Based on the comprehensive consideration of the characteristics of VGEs,geographic scene is proposed to organize geographic information and data.We empirically find that geographic scene provides a suitable organization schema to support geo-visualization,geo-simulation,and geo-collaboration.To systematically investigate the concept and method of geographic scene,Geographic Scenario is proposed as the theory on developing geographic scene,and corresponding key issues of the Geographic Scenario are illustrated in this article.Prospects of the proposed method are discussed with the hope of informing future studies of VGEs. | Guonian Lü Min Chen Linwang Yuan Liangchen Zhou Yongning Wen Mingguan Wu Bin Hu Zhaoyuan Yu Songshan Yue Yehua Sheng | 2018 | International Journal of Digital Earth2018，11，4： | 4 |
| 5 | Information geography: A new fulcrum of geographic ternary world显示文摘The development trend of ternary space requires the construction of the information space for information mapping,transmission and transformation of geographic elements and social-human elements. Relevant researches of information geography from the perspective of Geographic Information Science and human geography are reviewed in this paper, then the concept interpretation of information geography from the perspective of ternary space is proposed. It is presented in this paper that information geography can be constructed with a framework using seven geographic elements as the basic expressing dimensions and seven social-human elements as the basic aggregating core. Information geography analyzes spatio-temporal distribution, structural characteristics, evolution process and interactions of various elements in the information space. And it eventually realizes the actual description, multi-scenario simulation, multi-objective decision-making and multi-channel control of the physical world and the social-human world. | Guonian LÜ Linwang YUAN Zhaoyuan YU | 2022 | Science China Earth Sciences2022，65，2： | 4 |
| 6 | CAUSTA: Clifford Algebra Based Unified Spatio- Temporal Analysis显示文摘 | Yuan Linwang Yu Zhaoyuan Chen Shaofei | 2010 | Transactions in GIS2010，，： | 1 |
| 7 | Regional sea level change in Northwest Pacific: Process, characteristic and prediction显示文摘在地区性的海水平变化的西北太平洋边缘的海,这个过程,特征和预言基于 22 个稀少分布式的潮计量器记录被下列方法的集成讨论。第一,调整他们算法(RegEM ) 和多逐渐变细光谱方法(MTM ) 被采用解释他们的多尺度的变化过程和他们的空间时间的变化。第二,有序的簇方法被介绍分类这些潮汐的车站,并且与空间的考虑邻近的关系,我们获得五个分区( Bohai 海北的黄海的海岸,黄海东方中国海中国海岸,华东海日本海岸,南部的华东海和西北的华南海)。而且,吝啬的产生功能(MGF ) 被探索预言每个潮车站的中期、长期的趋势。最后,主要部件分析( PCA )被采用获得地区性规模的海水平变化趋势,从 2001~2030 的上述五个分区的海水平上升率分别地是 1.231.27 mm/a , 3.303.34 mm/a , 2.722.76 mm/a , 1.431.47 mm/a 和 1.131.15 mm/a ,并且整个区域海水平上升率在 2.01 mm/a 和 2.11 mm/a 之间。我们的工作的目的是在地区性的海水平变化上进行综合研究。 | LUO Wen YUAN Linwang YU Zhaoyuan YI Lin XIE Zhiren | 2011 | Journal of Geographical Sciences2011，21，3： | 1 |
| 8 | Evolutionary model of the central place hierarchical system显示文摘Central place theory is one of the two theoretical cornerstones of geography, yet it cannot be connected with other spatial structure models, fails to provide definite time-space parameter conditions, lacks an evolutionary process model, and does not easily enable construction of a complete theoretical system of regional spatial structure. This paper gives an in-depth analysis of the process and mechanism for production and evolution of central places of different grades, and constructs an evolutionary model of the central place hierarchical system. The results of deduction, analysis and simulation show that production and evolution of the central place hierarchical system may be divided into five stages. These stages are the embryonic, formative, improvement, maturation, and advancement stages. Affected by spatial location and centricity, central places have obvious differences in scale and functional structures. There are great differences in the scale of same-grade central places. However, low-grade central places could have larger scales than high-grade central places, and the central places of a central location may form the agglomeration area of central places. Based on the hypothesis condition of an isotropic plain, the research shows that it is possible not only to form proportional functional structures of central places, but also to produce non-proportional scale structures of central places, and thus to complete the transformation from rationalistic deduction of spatial equilibrium mode to an explanation and demonstration of an unbalanced practical model. | LU YuQi YUAN LinWang ZHONG YeXi | 2011 | Science China Earth Sciences2011，54，10： | 1 |
| 9 | CAUSTA: Clifford Algebra Based Unified Spatio-Tempo-ral Analysis 显示文摘 | YUAN Linwang YU Zhaoyuan CHEN Shaofei | 2010 | Transactions in GIS2010，14，： | 1 |
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