Chonglong Wu

Suitability evaluation of urban construction land based on geo-environmental factors of Hangzhou, China

Suitability evaluation of urban construction land based on geo-environmental factors is the process of determining the fitness of a given tract of land for construction. This process involves a consideration of the geomorphology, geology, engineering geology, geological hazards, and other geological factors and is the basis of urban construction land planning and management. With the support of Geographic Information Systems (GIS), grid analysis, and geo-spatial analysis techniques, four factor groups comprising nine separate subfactors of geo-environmental attributes were selected to be used in the evaluation of the suitability level for construction land in Hangzhou. This was based on K-means clustering and back-propagation (BP) neural network methods due to their advantages in fast computing, unique adaptive capacity, and self-organization. Simultaneously, the evaluation results based on K-means clustering and BP neural network were compared and analyzed, and the accuracy evaluation was set. The results showed that the geo-environmental suitability evaluation results of construction land based on K-means clustering and BP neural network were similar in terms of the distribution and scale of construction land suitability level. At the same time, the results of the two evaluation methods were consistent with the variability in suitability level, engineering geology, and hydrogeology of Hangzhou. The results also showed that the real advantage of the methods proposed in this paper lies in their capacity to streamline the mapping process and to ensure that the results are consistent throughout. The suitability level of the urban construction land based on the geo-environment in Hangzhou was divided into four construction sites: land for building super high-rise and high-rise buildings, land for building multistorey buildings, land for low-rise buildings, and nonbuilding land. The results of the suitability evaluation for each category will provide a scientific basis for decision-making in urban development in Hangzhou.

Ontology-aided annotation, visualization, and generalization of geological time-scale information from online geological map services

Geological maps are increasingly published and shared online, whereas tools and services supporting information retrieval and knowledge discovery are underdeveloped. In this study, we developed an ontology of geological time scale by using a Resource Description Framework model to represent the ordinal hierarchical structure of the geological time scale and to encode collected annotations of geological time scale concepts. We also developed an animated graphical view of the developed ontology, and functions for interactions between the ontology, the animation and online geological maps published as layers of OGC Web Map Service. The featured functions include automatic annotations for geological time concepts recognized from a geological map, changing layouts in the animation to highlight a concept, showing legends of geological time contents in an online map with the animation, and filtering out and generalizing geological time features in an online map by operating the map legend shown in the animation. We set up a pilot system and carried out a user survey to test and evaluate the usability and usefulness of the developed ontology, animation and interactive functions. Results of the pilot system and the user survey demonstrate that our works enhance features of online geological map services and they are helpful for users to understand and to explore geological time contents and features, respectively, of a geological map.

Changes of urban wetlands in Wuhan, China, from 1987 to 2005

Urban wetlands play a significant role in the sustainable development of the urban eco-environment. However, accelerated urbanization has caused rapid changes in urban wetland landscape patterns, which may seriously affect their functions. Based on land-use maps, TM images, and field data from the Wuhan wetlands, the spatiotemporal evolution and wetland landscape pattern were quantitatively analyzed, with reference to landscape ecology indices of diversity, fragmentation, dominance, shape, and dimension. The results showed that: (1) the natural wetland area decreased: lake wetlands and marsh wetlands decreased by 18.71% and 50.3% from 1987 to 2005, respectively; (2) artificial wetland area increased by 47.75% in Wuhan over the same period; (3) the lake wetland area of Wuhan declined due to the conversion of large lakes to smaller ones; (4) the value of the diversity index (H), evenness index (E), and fragmentation index (F) decreased, while the value of the dominance index (D) increased from 1987 to 2005; (5) the landscape shape index (LSI) and fractal dimension (FD) of the river wetlands, lake wetlands, bottomland wetlands, and marsh wetlands decreased, while the LSI and FD of the reservoir and pond wetlands increased from 1987 to 2005; and (6) natural, societal, and economic, as well as human, activities are major factors for the structural changes in the Wuhan wetland landscape, as revealed by canonical correlation analysis. Results suggest that the ecological environment of urban wetlands should be protected to maximize the services of urban wetland ecosystems in Wuhan, China.Urban wetlands play a significant role in the sustainable development of the urban eco-environment. However, accelerated urbanization has caused rapid changes in urban wetland landscape patterns, which may seriously affect their functions. Based on land-use maps, TM images, and field data from the Wuhan wetlands, the spatiotemporal evolution and wetland landscape pattern were quantitatively analyzed, with reference to landscape ecology indices of diversity, fragmentation, dominance, shape, and dimension. The results showed that: (1) the natural wetland area decreased: lake wetlands and marsh wetlands decreased by 18.71% and 50.3% from 1987 to 2005, respectively; (2) artificial wetland area increased by 47.75% in Wuhan over the same period; (3) the lake wetland area of Wuhan declined due to the conversion of large lakes to smaller ones; (4) the value of the diversity index (H), evenness index (E), and fragmentation index (F) decreased, while the value of the dominance index (D) increased from 1987 to 2005;...

Development of a controlled vocabulary for semantic interoperability of mineral exploration geodata for mining projects

Semantic interoperability of mineral exploration geodata is a long-term concern in mining projects. Inconsistent conceptual schemas and heterogeneous professional terms among various geodata sources in a mining project often hinder their efficient use and/or reuse. Our study of a controlled vocabulary focuses on interoperability of mineral exploration geodata of different mining projects of a mining group in China. In order to achieve this purpose, a proper representation of concepts and their inter-relationships in the knowledge domain of mineral exploration for mining projects is proposed. In addition, we propose that for wider interoperability of mining project geodata the controlled vocabulary underpinning them should be interoperable with concepts in related applications in the mineral exploration domain. In developing our controlled vocabulary, we adopted/adapted national standards of geosciences taxonomies and terminologies. The organization structure of terms, coding method, metadata schema for database applications and an extensible structure of our controlled vocabulary are discussed. The controlled vocabulary we developed was then used to reconcile heterogeneous geodata and to set up integrated databases for various mining projects of the mining group. Our study shows that a properly organized controlled vocabulary not only allows for efficient reconciliation of heterogeneous geodata sources in similar or related projects, but also makes related geodata to be interoperable with extramural applications in the same knowledge domain.

Decomposition tree: a spatio-temporal indexing method for movement big data

Movement is a complex process that evolves through both space and time. Movement data generated by moving objects is a kind of big data, which has been a focus of research in science, technology, economics, and social studies. Movement database is also at the forefront of geographic information science research. Developing efficient access methods for movement data stored in movement databases is of critical importance. Tree-like indexing structures such as the R-tree, Quadtree, Octree are not suitable for indexing multi-dimensional movement data because they all have high space cost of their inner nodes. In addition, it is difficult to use them for parallel access to multi-dimensional movement data because they thereof, are in hierarchical structures, which have severe overlapping problems in high dimensional space. In this paper, we propose a novel access method, the Decomposition Tree (D-tree), for indexing multi-dimensional movement data. The D-tree is a virtual tree without inner nodes, instead, through an encoding method based on integer bit-shifting operation, and can efficiently answer a wide range of queries. Experimental results show that the space cost and query performance of D-tree are superior to its best known competitors.

A SKOS-based multilingual thesaurus of geological time scale for interoperability of online geological maps

The usefulness of online geological maps is hindered by linguistic barriers. Multilingual geoscience thesauri alleviate linguistic barriers of geological maps. However, the benefits of multilingual geoscience thesauri for online geological maps are less studied. In this regard, we developed a multilingual thesaurus of geological time scale (GTS) to alleviate linguistic barriers of GTS records among online geological maps. We extended the Simple Knowledge Organization System (SKOS) model to represent the ordinal hierarchical structure of GTS terms. We collected GTS terms in seven languages and encoded them into a thesaurus by using the extended SKOS model. We implemented methods of characteristic-oriented term retrieval in JavaScript programs for accessing Web Map Services (WMS), recognizing GTS terms, and making translations. With the developed thesaurus and programs, we set up a pilot system to test recognitions and translations of GTS terms in online geological maps. Results of this pilot system proved the accuracy of the developed thesaurus and the functionality of the developed programs. Therefore, with proper deployments, SKOS-based multilingual geoscience thesauri can be functional for alleviating linguistic barriers among online geological maps and, thus, improving their interoperability.

Dynamic changes in Tangxunhu wetland over a period of rapid development (1953–2005) in Wuhan, China

Tangxunhu wetland is one of China’s largest freshwater lakes and plays a significant role in the sustainable development of the city of Wuhan. Based on terrain maps, TM images, and statistical data from 1953 to 2005, the spatial characters and changing features of Tangxunhu wetland were quantitatively assessed by calculating the landscape metrics of shape index (SI), fractal dimension (D), and stability index (S). The results showed that Tangxunhu wetland had meandrous development over the past 53 years, withSI, D, and S decreasing from 1953 to 1967, increasing from 1967 to 2000, and then decreasing again from 2000 to 2005.SI, D, andS were lowest in 1967, indicating maximuminstability, but highest in 2000, indicating maximum stability. These changes in Tangxunhu wetland were associated with various natural, social, and economic factors.

3D GIS database model for efficient management of large scale underground spatial data

One issue of GIS is management of huge amount of spatial data. Nowadays, acquisition capacity of 3D spatial data with various scales and resolutions is much more convenient due to new 3D acquisition technologies. It is a difficulty that how to efficiently and synthetically organize and manage large scale underground 3D spatial data with contents of continuous distribution and nonuniformity. A 3D GIS data management system framework with three layers is proposed to deal with large scale underground data integrated management. The related key issues and methods include: (1) Multi-scale underground spatial object concept model. (2) 3D spatial database model considering spatial and semantic relationship and corresponding data structure is introduced to support extendable storage environment such as file system, typical commercial database management system and cluster parallel system. (3) True 3D spatial index considering Level Of Detail (LOD). (4) Efficient dynamic dispatch method of great amount of 3D spatial data is adopted based on 3D data content and associated information. (5) 3D Spatial Data Engine (SDE) provides a uniform access interface for file management system, relational database management system and cluster parallel system and other applications. The 3D GIS database model focuses on the key issues of massive underground 3D spatial data provides a new way for the high performance database organization and management of true 3D geological data as well as its integration with the aboveground spatial data.

3D simulation of hydrocarbon-expulsion history: a method and its application

During the hydrocarbon expulsion simulation process, it is needed to consider the different mechanisms, modes and kinds of expulsion efficiency at different stages, as well as the changes of oil and gas phases, and the solubility of gas in oil and water. Aiming at the above issues, the combination of modelling methods with stages of normal-pressure hydrocarbon-expulsion and over-pressure episodic hydrocarbon-expulsion is used to calculate the volume of hydrocarbon-expulsion, and considering the gas solubility in oil and water and the changes of volume coefficient as well. Furthermore, by the way of reading coordinates to calculate the volume of each grid-cell in 3D geological model, final quantity of expelled hydrocarbon is calculated with pressure, temperature and residual volume of each cell. Finally, the 3D hydrocarbon-expulsion dynamic simulation module was developed and tested successfully by applying to the oil and gas pool-forming simulation in the Niuzhuang-Wangjiagang area, Dongying Depression, S...

Research and application of geological hazard domain ontology

Isomerous geological hazard data have four types: structural isomer, syntax isomer, system isomer and semantic isomer. Interoperability of semantic heterogenous data is a difficult issue due to its complexity and implication. Ontology not only describes exactly the meaning of concepts but also inner relationship of the concepts. So ontology can efficiently express common knowledge of specific domain by logic reasoning to get the implied relationship among concepts. Ontology is quite suitable to construct general semantic model for semantic data integration. There are three layers of geological hazard ontology: top-level ontology, domain ontology and application ontology which are used to build semantic integration and share model and differ from traditional data dictionary and metadata method. So the domain ontology plays the key role of link between top-level ontology and application ontology. Seven-step method is introduced to establish geo-hazard domain ontology. On the basis of related standards such as industry professional standard, geological hazard information processing standard and expert knowledge, geo-hazard domain ontology can be set up. Protégé 3.4.4 is developed by Stanford University is used in the establishment, management and inquiry access of the ontology with formalized representation by using OWL. Based on the abundant geological hazard data of Three Gorges Area in China, geological hazard ontology is applied to realize data and application integration and resolve the problem of decision making when single hazard or group hazards occur. Ontology is used to carry out semantic sharing model to improve interoperability capacity of geological hazard information system.