The Deep Packet Inspection(DPI)method is a popular method that can accurately identify the flow data and its corresponding application.Currently,the DPI method is widely used in common network management systems.Howev...The Deep Packet Inspection(DPI)method is a popular method that can accurately identify the flow data and its corresponding application.Currently,the DPI method is widely used in common network management systems.However,the major limitation of DPI systems is that their signature library is mainly extracted manually,which makes it hard to efficiently obtain the signature of new applications.Hence,in this paper,we propose an automatic signature extraction mechanism using Principal Component Analysis(PCA)technology,which is able to extract the signature automatically.In the proposed method,the signatures are expressed in the form of serial consistent sequences constructed by principal components instead of normally separated substrings in the original data extracted from the traditional methods.Extensive experiments based on numerous sets of data have been carried out to evaluate the performance of the proposed scheme,and the results prove that the newly proposed method can achieve good performance in terms of accuracy and efficiency.展开更多
Energy flow drives the complex systems to evolve.The allometric scaling as the universalenergy flow pattern has been found in different scales of ecological systems.It reflects the generalpower law relationship betwee...Energy flow drives the complex systems to evolve.The allometric scaling as the universalenergy flow pattern has been found in different scales of ecological systems.It reflects the generalpower law relationship between flow and store.The underlying mechanisms of energy flow patterns areexplained as the branching transportation networks which can be regarded as the result of systematicoptimization of a biological target under constraints.Energy flows in the ecological system may bemodelled by the food web model and population dynamics on the network.This paper reviews thelatest progress on the energy flow patterns,explanatory models for the allometric scaling and modellingapproach of flow and network evolution dynamics in ecology.Furthermore,the possibility of generalizingthese flow patterns,modelling approaches to other complex systems is discussed.展开更多
Flow measurement is important in the fluid process and transmission system. For the need of accuracy measure- ment of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may p...Flow measurement is important in the fluid process and transmission system. For the need of accuracy measure- ment of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may pro- duce swirling flow in the natural gas pipeline networks system and many other industry fields. In order to reveal the influence of upstream swirling flow on internal flow fields and the metrological characteristics, numerical si- mulations are carried out on the swirl meter. Using RNG k-e turbulent model and SIMPLE algorithm, the flow field is numerically simulated under swirling flows generated from co-swirl and counter-swirl flow. Simulation results show fluctuation is enhanced or weakened depending on the rotating direction of swirling flow. A coun- ter-swift flow increases the entropy production rate at the inlet and outlet of the swirler, the junction region between throat and divergent section, and then the pressure loss is increased. The vortex precession dominates the static pressure distributions on the solid walls and in the channel, especially at the end region of the throat.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.61003282Beijing Higher Education Young Elite Teacher Project+3 种基金China Next Generation Internet(CNGI)Project"Research and Trial on Evolving Next Generation Network Intelligence Capability Enhancement(NICE)"the National Basic Research Program(973 Program)under Grant No.2009CB320-505the National Science and Technology Major Project"Research about Architecture of Mobile Internet"under Grant No.2011ZX03-002-001-01the National High Technology Research and Development Program(863 Program)under Grant No.2011AA010704
文摘The Deep Packet Inspection(DPI)method is a popular method that can accurately identify the flow data and its corresponding application.Currently,the DPI method is widely used in common network management systems.However,the major limitation of DPI systems is that their signature library is mainly extracted manually,which makes it hard to efficiently obtain the signature of new applications.Hence,in this paper,we propose an automatic signature extraction mechanism using Principal Component Analysis(PCA)technology,which is able to extract the signature automatically.In the proposed method,the signatures are expressed in the form of serial consistent sequences constructed by principal components instead of normally separated substrings in the original data extracted from the traditional methods.Extensive experiments based on numerous sets of data have been carried out to evaluate the performance of the proposed scheme,and the results prove that the newly proposed method can achieve good performance in terms of accuracy and efficiency.
基金supported by Guozhi Xu Post Doctoral Research Foundationthe National Natural Science Foundation of China under Grant No. 60574068.
文摘Energy flow drives the complex systems to evolve.The allometric scaling as the universalenergy flow pattern has been found in different scales of ecological systems.It reflects the generalpower law relationship between flow and store.The underlying mechanisms of energy flow patterns areexplained as the branching transportation networks which can be regarded as the result of systematicoptimization of a biological target under constraints.Energy flows in the ecological system may bemodelled by the food web model and population dynamics on the network.This paper reviews thelatest progress on the energy flow patterns,explanatory models for the allometric scaling and modellingapproach of flow and network evolution dynamics in ecology.Furthermore,the possibility of generalizingthese flow patterns,modelling approaches to other complex systems is discussed.
基金supported by the National Natural Science Foundation of China(51579225)
文摘Flow measurement is important in the fluid process and transmission system. For the need of accuracy measure- ment of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may pro- duce swirling flow in the natural gas pipeline networks system and many other industry fields. In order to reveal the influence of upstream swirling flow on internal flow fields and the metrological characteristics, numerical si- mulations are carried out on the swirl meter. Using RNG k-e turbulent model and SIMPLE algorithm, the flow field is numerically simulated under swirling flows generated from co-swirl and counter-swirl flow. Simulation results show fluctuation is enhanced or weakened depending on the rotating direction of swirling flow. A coun- ter-swift flow increases the entropy production rate at the inlet and outlet of the swirler, the junction region between throat and divergent section, and then the pressure loss is increased. The vortex precession dominates the static pressure distributions on the solid walls and in the channel, especially at the end region of the throat.
