There is an increasing number of Internet applications, which leads to an increasing network capacity and availability. Internet traffic characterisation and application identification are, therefore, more important f...There is an increasing number of Internet applications, which leads to an increasing network capacity and availability. Internet traffic characterisation and application identification are, therefore, more important for efficient network management. In this paper, we construct flow graphs from detailed Internet traffic data collected from the public networks of Internet Service Providers. We analyse the community structures of the flow graph that is naturally formed by different applications. The community size, degree distribution of the community, and community overlap of 10 Internet applications are investigated. We further study the correlations between the communities from different applications. Our results provide deep insights into the behaviour Internet applications and traffic, which is helpful for both network management and user behaviour analysis.展开更多
Under strong shocks,long-span spatial-latticed structures may collapse due to dynamic instability or strength failure.The elasto-plastic dynamic behaviors of three spatiallatticed structures,including two double-layer...Under strong shocks,long-span spatial-latticed structures may collapse due to dynamic instability or strength failure.The elasto-plastic dynamic behaviors of three spatiallatticed structures,including two double-layer cylindrical shells and a spheri-cal shell used for the 2008 Olympic Games in Beijing,were quantitatively examined under multi-support excitation(MSE) and uniform support excitation(USE).Numerical analyses described several important parameters such as the peak acceleration and displacement responses at key joints,the number and distribution of plastic elements,and the deformation of the shell at the moment of collapse.Results of the analysis revealed the features and the failure mechanism of the spatial-latticed structures under MSE and USE.In both scenarios,the double-layer reticulated shell collapsed in the "overflow" mode,collapse was govrned by the number of invalid plastic elements rather than the total number of plastic elements,and the collapse of the structure began with damage to certain local regions near the supports.By comparing the numbers and distributions of the plastic members under MSE to those under USE,it was observed that the plastic members spread more sufficiently and the internal forces were more uniform under MSE,especially for lower apparent velocities in soils.Due to the effects of pseudo-static displacement,the stresses in members near supports under MSE were higher than those under USE.These regions are prone to failure during earthquakes and deserve special attention in the seismic design of reticulated structures.展开更多
The authors extend the Gazi＇s swarm model with local neighbor rules and the dynamic communication topology, and study its aggregation properties. Results of analysis show that all agents in the models aggregate and e...The authors extend the Gazi＇s swarm model with local neighbor rules and the dynamic communication topology, and study its aggregation properties. Results of analysis show that all agents in the models aggregate and eventually form a cohesive cluster of finite size around the swarm center or the appointed point. Finally, simulations are provided to testify some of the results. Models in the paper are more applicable to the reality for the advantage that each agent only needs the partial information of the entire dynamic system when making motion decision.展开更多
The function of a network is affected by its structure. For example, the presence of highly interactive individuals, or hubs, influences the extent and rate of information spread across a network. In a network of inte...The function of a network is affected by its structure. For example, the presence of highly interactive individuals, or hubs, influences the extent and rate of information spread across a network. In a network of interactions, the duration over which individual variation in interactions persists may affect how the network operates. Individuals may persist in their behavior over time and across situations, often referred to as personality. Colonies of social insects are an example of a biological system in which the structure of the coordinated networks of interacting workers may greatly influence information flow within the colony, and therefore its collective behavior. Here I investigate the effects of persistence in walking patterns on interaction networks us- ing computer simulations that are parameterized using observed behavior of harvester ants. I examine how the duration of persis- tence in spatial behavior influences network structure. Furthermore, I explore how spatial features of the environment affect the relationship between persistent behavior and network structure. I show that as persistence increases, the skewness of the weighted degree distribution of the interaction network increases. However, this relationship holds only when ants are confined in a space with boundaries, but not when physical barriers are absent. These findings suggest that the influence of animal personalities on network structure and function depends on the environment in which the animals reside [Current Zoology 61 （1）： 98-106, 2015].展开更多
Network and equation-based （EB） models are two prominent methods used in the study of epidemics. While EB models use a global approach to model aggregate population, net- work models focus on the behavior of individ...Network and equation-based （EB） models are two prominent methods used in the study of epidemics. While EB models use a global approach to model aggregate population, net- work models focus on the behavior of individuals in the population. The two approaches have been used in several areas of research, including finance, computer science, social science and epidemiology. In this study, epidemiology is used to contrast EB models with network models. The methods are based on the assumptions and properties of compartmental models. In EB models we solve a system of ordinary differential equations and in network models we simulate the spread of epidemics on contact networks using bond percolation. We examine the impact of network structures on the spread of infection by considering various networks, including Poisson, Erd3s R6nyi, Scale-free, and Watts- Strogatz small-world networks, and discuss how control measures can make use of the network structures. In addition, we simulate EB assumptions on Watts-Strogatz net- works to determine when the results are similar to that of EB models. As a case study, we use data from the 1918 Spanish flu pandemic and that from measles outbreak to validate our results.展开更多
基金supported by the National Natural Science Foundation of Chinaunder Grant No.61171098the Fundamental Research Funds for the Central Universities of Chinathe 111 Project of China under Grant No.B08004
文摘There is an increasing number of Internet applications, which leads to an increasing network capacity and availability. Internet traffic characterisation and application identification are, therefore, more important for efficient network management. In this paper, we construct flow graphs from detailed Internet traffic data collected from the public networks of Internet Service Providers. We analyse the community structures of the flow graph that is naturally formed by different applications. The community size, degree distribution of the community, and community overlap of 10 Internet applications are investigated. We further study the correlations between the communities from different applications. Our results provide deep insights into the behaviour Internet applications and traffic, which is helpful for both network management and user behaviour analysis.
文摘Under strong shocks,long-span spatial-latticed structures may collapse due to dynamic instability or strength failure.The elasto-plastic dynamic behaviors of three spatiallatticed structures,including two double-layer cylindrical shells and a spheri-cal shell used for the 2008 Olympic Games in Beijing,were quantitatively examined under multi-support excitation(MSE) and uniform support excitation(USE).Numerical analyses described several important parameters such as the peak acceleration and displacement responses at key joints,the number and distribution of plastic elements,and the deformation of the shell at the moment of collapse.Results of the analysis revealed the features and the failure mechanism of the spatial-latticed structures under MSE and USE.In both scenarios,the double-layer reticulated shell collapsed in the "overflow" mode,collapse was govrned by the number of invalid plastic elements rather than the total number of plastic elements,and the collapse of the structure began with damage to certain local regions near the supports.By comparing the numbers and distributions of the plastic members under MSE to those under USE,it was observed that the plastic members spread more sufficiently and the internal forces were more uniform under MSE,especially for lower apparent velocities in soils.Due to the effects of pseudo-static displacement,the stresses in members near supports under MSE were higher than those under USE.These regions are prone to failure during earthquakes and deserve special attention in the seismic design of reticulated structures.
基金Project Operation and Simulation of Emergency Response Logistics Network in the System of Anti-bioterrorism supported by the National Natural Science Foundation of China under Grant No.70671021.
文摘The authors extend the Gazi＇s swarm model with local neighbor rules and the dynamic communication topology, and study its aggregation properties. Results of analysis show that all agents in the models aggregate and eventually form a cohesive cluster of finite size around the swarm center or the appointed point. Finally, simulations are provided to testify some of the results. Models in the paper are more applicable to the reality for the advantage that each agent only needs the partial information of the entire dynamic system when making motion decision.
文摘The function of a network is affected by its structure. For example, the presence of highly interactive individuals, or hubs, influences the extent and rate of information spread across a network. In a network of interactions, the duration over which individual variation in interactions persists may affect how the network operates. Individuals may persist in their behavior over time and across situations, often referred to as personality. Colonies of social insects are an example of a biological system in which the structure of the coordinated networks of interacting workers may greatly influence information flow within the colony, and therefore its collective behavior. Here I investigate the effects of persistence in walking patterns on interaction networks us- ing computer simulations that are parameterized using observed behavior of harvester ants. I examine how the duration of persis- tence in spatial behavior influences network structure. Furthermore, I explore how spatial features of the environment affect the relationship between persistent behavior and network structure. I show that as persistence increases, the skewness of the weighted degree distribution of the interaction network increases. However, this relationship holds only when ants are confined in a space with boundaries, but not when physical barriers are absent. These findings suggest that the influence of animal personalities on network structure and function depends on the environment in which the animals reside [Current Zoology 61 （1）： 98-106, 2015].
文摘Network and equation-based （EB） models are two prominent methods used in the study of epidemics. While EB models use a global approach to model aggregate population, net- work models focus on the behavior of individuals in the population. The two approaches have been used in several areas of research, including finance, computer science, social science and epidemiology. In this study, epidemiology is used to contrast EB models with network models. The methods are based on the assumptions and properties of compartmental models. In EB models we solve a system of ordinary differential equations and in network models we simulate the spread of epidemics on contact networks using bond percolation. We examine the impact of network structures on the spread of infection by considering various networks, including Poisson, Erd3s R6nyi, Scale-free, and Watts- Strogatz small-world networks, and discuss how control measures can make use of the network structures. In addition, we simulate EB assumptions on Watts-Strogatz net- works to determine when the results are similar to that of EB models. As a case study, we use data from the 1918 Spanish flu pandemic and that from measles outbreak to validate our results.
