Research And Implementation Of GIS For Civil Air Defense Based On Hybrid-Pattern Architecture

The rapid development of science and technology has promoted social progress, and the National Civil Defense in the new era also has an urgently need of information construction. The civil defense system must combine with geographic information systems (GIS) technology. By using the powerful advantage in spatial query and spatial analysis of GIS, the system can contain query, statistics and analysis so that the function is gathered in integral whole, and then achieve the purpose of increasing efficiency and scientific analyzing in civil air preplan. Therefore, this paper has designed and implemented the Civil Defense Electronic Map System based on hybrid-pattern architecture which combines C/S and B/S. This system has a good interactive and flexible application. It can not only be easily applied to various sectors of civil defense system, but also do a comprehensive spatial statistics and analysis, timely understanding of the spatial and temporal changes in civil defense projects which can provide an effective basis for scientific decision-making.The main researches in this paper are as follows:1. By analyzing the applications of traditional C/S and B/S system architecture in the GIS development, we propose the hybrid-pattern architecture which combines C/S and B/S and then use it in developing civil defense system. This model has lots of advantages. On the one hand, it can make it easier for officers in such departments to use the system, on the other hand, it can be can be targeted to provide a completely spatial statistics and analysis and better meets the high requirements about the security of data;2. For the maintenance of data consistency between subsystems in the hybrid-pattern architecture, this paper presents a new program with a high level of security and independence. The program mainly includes:(1) subsystems operate their own independent databases and the two databases have master-slave nature for being able to ensure the security of data better; (2)Two logs are the basic to maintain data consistency between the two systems, the operation of the temporary database by B/ S users must be checked by C/S users, All audit operations must be recorded in the log, which improve the maintainability of the system;3. This paper overcomes the deficiency of buffer analysis which is general in the previous research and proposes a buffer analysis method based on evacuation time. This method combines the shortest path analysis and buffer analysis, and then obtains the shortest distance of temporary aggregation point and air defence fortifications by Dijkstra algorithm. At last, algorithm and application example of buffer analysis based on evacuation time are also proposed.4. By using ASP.NET, Ajax and other technologies, software such as MapXtreme and MapInfo, we realize XX City's civil defense electronic map system based on hybrid-pattern architecture. The system includes a map view and editing, spatial query and analysis and management for air-defense facilities, etc. It can provide strong support for the civil air preplan assistant decision system.