A new paradigm of scalable routing for ICN is to combine a geometric routing scheme with a Distributed Hash Table. However, for most routing schemes in this paradigm, when a node joins or leaves, large numbers of node...A new paradigm of scalable routing for ICN is to combine a geometric routing scheme with a Distributed Hash Table. However, for most routing schemes in this paradigm, when a node joins or leaves, large numbers of nodes, even the whole topology, need to be re-embedded, and a great number of contents need to be re-registered. In this paper, we propose D-Griffin, a geometric routing scheme on flat names for dynamic topologies. D-Griffin provides two advantages. First, it avoids re-embedding the topology by using an online greedy embedding scheme and a void handling greedy forwarding scheme. Second, it decreases the number of re-registrations by using a name mapping scheme with a tradeoff between topology independence and load balancing. Theoretical and experimental analyses show that D-Griffin provides guaranteed content lookup, low description complexity, low path stretch, scalable routing update, and acceptable load balancing.展开更多
At the present time, world agriculture is influenced by a set of new technologies grouped under the generic name of precision agriculture （PA）. Based on a study of the cotton sector, this article examines the effect...At the present time, world agriculture is influenced by a set of new technologies grouped under the generic name of precision agriculture （PA）. Based on a study of the cotton sector, this article examines the effects of adopting PA with regard to international trade. We examine whether PA can contribute to the further destabilization of the terms of trade between countries in Central and West Africa （CWA） and Northern countries. We show that PA can be used by Northern countries at the expense of CWA, since it is used to implement strategic commercial policies based on subsidies. These policies are made more credible by the fact that international authorities cannot easily condemn them.展开更多
ymmetry of the world trade network provides a novel perspective to understand the world-wide trading system. However, symmetry in the world trade network （WTN） has been rarely studied so far. In this paper, the auth...ymmetry of the world trade network provides a novel perspective to understand the world-wide trading system. However, symmetry in the world trade network （WTN） has been rarely studied so far. In this paper, the authors systematically explore the symmetry in WTN. The authors construct WTN in 2005 and explore the size and structure of its automorphism group, through which the authors find that WTN is symmetric, particularly, locally symmetric to a certain degree. Furthermore, the authors work out the symmetric motifs of WTN and investigate the structure and function of the symmetric motifs, coming to the conclusion that local symmetry will have great effect on the stability of the WTN and that continuous symmetry-breakings will generate complexity and diversity of the trade network. Finally, utilizing the local symmetry of the network, the authors work out the quotient of WTN, which is the structural skeleton dominating stability and evolution of WTN.展开更多
基金supported in part by the National Key Basic Research Program of China(973 Program) under Grant No. 2011CB302605,2013CB329602the National Natural Science Foundation of China under Grant No.61202457,61402149
文摘A new paradigm of scalable routing for ICN is to combine a geometric routing scheme with a Distributed Hash Table. However, for most routing schemes in this paradigm, when a node joins or leaves, large numbers of nodes, even the whole topology, need to be re-embedded, and a great number of contents need to be re-registered. In this paper, we propose D-Griffin, a geometric routing scheme on flat names for dynamic topologies. D-Griffin provides two advantages. First, it avoids re-embedding the topology by using an online greedy embedding scheme and a void handling greedy forwarding scheme. Second, it decreases the number of re-registrations by using a name mapping scheme with a tradeoff between topology independence and load balancing. Theoretical and experimental analyses show that D-Griffin provides guaranteed content lookup, low description complexity, low path stretch, scalable routing update, and acceptable load balancing.
文摘At the present time, world agriculture is influenced by a set of new technologies grouped under the generic name of precision agriculture （PA）. Based on a study of the cotton sector, this article examines the effects of adopting PA with regard to international trade. We examine whether PA can contribute to the further destabilization of the terms of trade between countries in Central and West Africa （CWA） and Northern countries. We show that PA can be used by Northern countries at the expense of CWA, since it is used to implement strategic commercial policies based on subsidies. These policies are made more credible by the fact that international authorities cannot easily condemn them.
基金supported by the National Natural Science Foundation of China under Grant No. 70371070 Shanghai Leading Academic Discipline Project under Grant No. S30504Key Project for Fundamental Research of STCSM under Grant No. 06JC14057
文摘ymmetry of the world trade network provides a novel perspective to understand the world-wide trading system. However, symmetry in the world trade network （WTN） has been rarely studied so far. In this paper, the authors systematically explore the symmetry in WTN. The authors construct WTN in 2005 and explore the size and structure of its automorphism group, through which the authors find that WTN is symmetric, particularly, locally symmetric to a certain degree. Furthermore, the authors work out the symmetric motifs of WTN and investigate the structure and function of the symmetric motifs, coming to the conclusion that local symmetry will have great effect on the stability of the WTN and that continuous symmetry-breakings will generate complexity and diversity of the trade network. Finally, utilizing the local symmetry of the network, the authors work out the quotient of WTN, which is the structural skeleton dominating stability and evolution of WTN.
