A practical hierarchical component-based WebGIS model referred to as Geo-Union is presented. Geo-Union consists of four layers: storage layer, service layer, component layer and application layer. Service layer is partitioned into another two layers: Geo-Union client and Geo-Union server. The architectures and object diagram of each layer in Geo-Union are discussed in details. After that, four ...

An argumentation map is an online discussion forum for spatially related topics that combines the forum with an interactive map. The utility of an argumentation mapping tool highly depends on the accuracy and quantity of the geo-tags that link the discussion contributions to geographic locations. These geo-tags can be created manually by the users of the argumentation map or automatically by a ...

identifying the change trends in forms of land surface is one of the main topics in geomorphic system. in this view, we try to assess the stability level of geo systems, boundary changes, instability and prediction of surface forms and processes response. this paper tries to conduct a comparative analysis on the geomorphic equilibrium paradigms, critical thresholds, environmental and natural ha...

We have recently been witnessing the growing establishment of map-centered web-based geo-portals on national, regional and local levels. However, a particular issue with these geo-portals is that each instance has been implemented in different ways in terms of design, usability, functionality, interaction possibilities, map size and symbologies. In this paper, we try to tackle these shortcoming...

Recently ontology research has received much attention in geo-information science and the concept of ontology is very important for spatial information concept modeling and data sharing, classification of geographical classes. More importantly, it enriches the semantic theory of spatial information. Geo-information services and geo-information interpretation and extraction are the two main appl...

For a spanning tree T in a nontrivial connected graph G and for vertices u and v inG, there exists a unique u−v path u = u0, u1, u2, . . ., uk = v in T . A u− v T -path in G is a u− v path u = v0, v1, . . . , vl = v in G that is a subsequence of the sequence u = u0, u1, u2, . . . , uk = v. A u− v T -path of minimum length is a u− v T -geodesic in G. The T distance dG|T (u, v) from u to v in G i...

The structures of three xGeO(2)-(1- x)P(2)O(5) glasses, where x = 0.98,0.88, and 0.81, have been studied by neutron and x-ray diffraction experiments that yield well resolved P-O and Ge-O bond distances. The Ge-O coordination number (N(GeO)) increased from 4.0 ± 0.2 to 4.5 ± 0.2 with the decrease in x from 0.98 to 0.81. The increase in N(GeO) is consistent with a structural model that assumes t...

3D geo-database research is a promising field to support challenging applications such as 3D urban planning, environmental monitoring, infrastructure management, and early warning or disaster management and response. In these fields, interdisciplinary research in GIScience and related fields is needed to support the modelling, analysis, management, and integration of large geo-referenced data s...