Geographic information system （GIS） is increasingly managing very large sets of data, hence a centralized data index may not always provide the most scalable solution. Recently, the peer to peer （P2P） networks hav...Geographic information system （GIS） is increasingly managing very large sets of data, hence a centralized data index may not always provide the most scalable solution. Recently, the peer to peer （P2P） networks have become very popular for sharing information in a totally decentralized manner. In this paper, a new hybrid P2P spatial indexing network （HPSIN） is proposed, which combines distributed quad-tree with distributed Hash table （DHT） based Chord network to maintain both query efficiency and system load balance. In addition, a simple theoretical model based on opened queueing network for HPSIN is established. Assuming each peer as M/M/1 queueing processor in the model, fundamental characteristics of the system is captured, and expression of average query delay is obtained in close form. The theoretical analysis and numerical computing results show that there exists an optimum point of tradeoff between efficiency and load balance. By setting a proper value of start index level ls for different network scale and query rate, HPSIN will achieve the minimum overall query delay, therefore, can adapt to different P2P application environments.展开更多
By means of variational structure and Z2 group index theory, we obtain infinite periodic solutions to a class of second-order neutral differential equations.
By means of variational structure and Z 2 group index theory,we obtain infinite periodic solutions to a class of second-order neutral differential equations.
基金supported by the Hi-Tech Research and Development Program of China (2009AA12Z219)the National Natural Science Foundation of China (40801149)+1 种基金the Jiangsu Province Bureau of Surveying and Mappings Research Fund (JSCHKY200810)Visiting Scholar Foundation of Key Lab. In University, the NJUPT Research Fund (NY206009)
文摘Geographic information system （GIS） is increasingly managing very large sets of data, hence a centralized data index may not always provide the most scalable solution. Recently, the peer to peer （P2P） networks have become very popular for sharing information in a totally decentralized manner. In this paper, a new hybrid P2P spatial indexing network （HPSIN） is proposed, which combines distributed quad-tree with distributed Hash table （DHT） based Chord network to maintain both query efficiency and system load balance. In addition, a simple theoretical model based on opened queueing network for HPSIN is established. Assuming each peer as M/M/1 queueing processor in the model, fundamental characteristics of the system is captured, and expression of average query delay is obtained in close form. The theoretical analysis and numerical computing results show that there exists an optimum point of tradeoff between efficiency and load balance. By setting a proper value of start index level ls for different network scale and query rate, HPSIN will achieve the minimum overall query delay, therefore, can adapt to different P2P application environments.
基金Project supported by NNSF of China (10471155)the Foundation of the Guangdong Province Natural Science Committee (031608) a specific Foundation for PhD Specialities of Educational Department of China (20020558092).
文摘By means of variational structure and Z2 group index theory, we obtain infinite periodic solutions to a class of second-order neutral differential equations.
基金Sponsored by the key NSF of Education Ministry of China (No.207047)
文摘By means of variational structure and Z 2 group index theory,we obtain infinite periodic solutions to a class of second-order neutral differential equations.
