Localization is one of the most important technologies in wireless sensor networks. A lightweight distributed node localization scheme is proposed by considering the limited computational capacity of WSNs. The proposed scheme introduces the virtual force model to determine the location by incremental refinement. Aiming at solving the drifting problem and malicious anchor problem, a location verification algorithm based on the virtual force mode is presented. In addition, an anchor promotion algorithm using the localization reliability model is proposed to re-locate the drifted nodes. Extended simulation experiments indicate that the localization algorithm has relatively high precision and the location verification algorithm has relatively high accuracy. The communication overhead of these algorithms is relative low, and the whole set of reliable localization methods is practical as well as comprehensive.
This paper presents an XML-Based Collaborative Documents Model. It describes the content system and related information of Collaborative Documents needed in the Real-Time Collaborative Environment which includes access control, concurrence control, document management, document state records and so on. Using XML to define a set of collaborative documents tags and DTD formats, then describe the collaborative documents. In this way, users can understand the meaning of data in the documents, and the system can process some data, such as access control, data search, data sort, storage management and the standard of communications. In this papec we design a basic real-time collaborative system frame based on the JSDT technology of the SUN Company.
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