Chen Nengcheng

A new approach to a local e-government portal for information management and deep searching

The paper introduces a new approach, that is, semantic Web techniques, to shed a new light on the solutions for local e-government information portal. After taking the comparison between traditional approaches and semantic approaches, the design of architecture and components of a local e-government information portal are illustrated in details based on semantic technologies. The paper also researches on the core technologies of implementation of the new approach, including the definition of e-government information portal Ontologies and searching algorithms.

Soil moisture estimation based on BeiDou B1 interference signal analysis

BeiDou Navigation Satellite System reflectometry (BDS-R) is an emerging area of BD (BeiDou) applications that uses multipath reflected signals in microwave remote sensing. Soil moisture estimation is one of the potential important applications of BDS-R. This study aims to investigate the feasibility of soil moisture estimation based on BD B1 band interference signals, which are composed of direct and reflected BD signals and can be readily captured using low-cost commercial BDS receivers. In this paper, a theoretical background for soil estimation from interference signals was introduced, and an analysis of field experimental data was conducted. First, a cosine model for the interference signal power was built, and a non-uniform power spectrum analysis was performed on the received interference signals to determine its main frequency. Then, a least squares curve fitting was applied on the interference signal power to extract its phase. The relationship between the soil moisture and the phase was then determined. Two months of experimental data were collected at BaoXie, Wuhan and analyzed for further inversion. Experimental results show that the phase of the interference signals increases with the increase of soil moisture. The correlation coefficient between the phase and the in-situ soil moisture value is approximately 0.8. Finally, the relationship between the phase and soil moisture is employed to estimate soil moisture. Results show that using BDS-R to measure soil moisture is feasible, which demonstrates a great potential of new application of the BD system.

Distribution of large volume image data using the mixed mode of Java Servlet and COM on Web

This paper reports some researches on distribution of large volume image data using techniques of the Mixed Mode of Java Servlet and COM on Web. The architecture and key technologies are discussed in detail. The web distribution system of image is implemented and the system is tested by the application instances. At last, the advantages and disadvantages for this web image distribution mode are analyzed.

King George Island spatial data model

Distribution, interoperability, interactivity, component are four main features of distributed GIS. Based on the principle of hypermap, hypermedia and distributed database, the paper comes up with a kind of distributed spatial data model which is in accordance with those features of distributed GIS. The model takes catalog service as the outline of spatial information globalization, and defines data structure of hypermap node in different level. based on the model, it is feasible to manage and process distributed spatial information, and integrate multi-source, heterogeneous spatial data into a framework. Traditionally, to retrieve and access spatial data via Internet is only by theme or map name. With the concept of the model, it is possible to retrieve, load, and link spatial data by vector-based graphics on the Internet.

A distributed hypermap model for internet gis

The rapid development of Internet technology makes it possible to integrate GIS with the Internet, forming Internet GIS. Internet GIS is based on a distributed client/server architecture and TCP/IP & IIOP. When constructing and designing Internet GIS, we face the problem of how to express information units of Internet GIS. In order to solve this problem, this paper presents a distributed hypermap model for Internet GIS. This model provides a solution to organize and manage Internet GIS information units. It also illustrates relations between two information units and in an internal information unit both on clients and servers. On the basis of this model, the paper contributes to the expressions of hypermap relations and hypermap operations. The usage of this model is shown in the implementation of a prototype system.