Research For Scale-free Network Model And Cascading Failure

Research in scale-free network is seeping in the mathematical,life sciences, engineering and many other different domains.Scientific understanding of quantitative and qualitative for scale-free network becomes an important challenging topic in scientific research in network time.In the study of scale-free network,the evolving model of scale-free network always becomes the key point and hot spot. The goal of network model research is making pepople better understanding and simulating on the network evolving process and the relationship between network architecture and behavior,and then consider the imporovement of network beehavior consequently. Cascading failure of scale-free network is defined as one or a few nodes or sides failure which will lead other nodes failure through the coupling relations, and it will cause the chain effect and lots of nodes failure,even the collapse of the whole network, also vividly called "avalanche". As human society networking increasingly,people become more and more strict with the security and reliability of scale-free network ,and also have made lots of efforts,however,large-scale failures still occur sometimes.Therefore,it is necessary to do research for occurrence mechanism, prevention and control of cascading failure.In the beginning of this thesis, the basic concept of scale-free network,several important network model and cascading failure model are summarized, and then based on those, section two illustates some research for improvement of local-world evolving network model and cascading failure of local-world evolving network based on coupled map lattice. The main works and innovative results are listed as follow:Firstly, it will research in the basic topology concept and property of scale-free network,and several important model based on property and phenomenon of real network,then based on those several improvements are made in the local-world evolving network model.The goal of improvements is making the simulating on the evolving process of network better. Three improvements are made in local-world evolving network model:add edge,delete old edge and rewire mechanism;control mechanism of node degreee;local-world increasing mechanism.And for the improved model,mathematical reasoning and simulation are done later. Experimental results show that improved model is not only maintaining the orginal character of network,also close to the reality of network evolving process.Secondly, it will research in several cascading failure models ,and based on those, we will do some research on cascading failure of local-world evolving network. In conclusion local-world evolving network based on coupled map lattice is advanced and two policies are used in the local-world evolving CML:random failures and deliberate attacks. Experimental results show that deliberate attacks leading to cascading failures are intens than random failures in local-world evolving CML,and threshold of local-world evolving CML is small than BA scale-free's. All of those show that it's easy for local-world evolving network model to cause cascading failure.