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Dive into the research topics where Liu An-feng is active.

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Featured researches published by Liu An-feng.


international conference on pervasive computing | 2007

Treenet:A Web Services Composition Model Based on Spanning tree

Liu An-feng; Chen Zhi-gang; He Hui; Gui Weihua

Recently, Web service composition based on the Service Overlay Network has drawn much research attention. In this paper, we present a composition model capable of composing Web services across wide area networks with the service composition based on interface idea integrated with Peer to Peer technologies. It forms a novel Web Services Composition Overlay Network (WSCON) with Peer to Peer technologies, then associate nodes in the same Web services composition domain to form the Web Services Composition Network, according to domain ontology and its reasoning ability. Web service discovery and composition entry are performed through Distributed Hash Table (DHT). We have conducted extensive experiments using large-scale simulations. The experiment results show the advantages of our model: supporting Web service composition based on QoS, high composition success rate, fast service distribution, discovery and composition, and tolerant to dynamic service component node arrivals and departures.


international conference for young computer scientists | 2008

Research on Energy Hole Problem for Wireless Sensor Networks Based on Alternation between Dormancy and Work

Liu An-feng; Wu Xian-you; Gui Weihua

This paper theoretically proposes a more accurate analytical method for avoiding energy hole in wireless sensor networks with nonuniform node distribution. Based on the typical energy consumption model of wireless sensor networks, we obtain the relationship of the densities of sensor nodes in different regions of network through rigorous mathematical analysis, and prove that if the densities of sensor nodes working at the same time are, the entire work can achieve uniform energy consumption by making the sensor nodes whose density is greater than alternate between dormancy and work. Through theoretical analysis and numerical simulation, we obtain the following conclusions: 1) Under the circumstance that the parameters of network do not change, the network lifetime can increase several times by selecting appropriate transmission radius of sensor node. 2) To achieve uniform energy consumption of network, the densities of sensor nodes whose distances from the base station are different should be different. Even if the sensor nodes were in the same circular ring, the densities of sensor nodes in different places should not the same. 3) Through nonuniform node distribution and alternation between dormancy and work, the efficiency of network can increase several times and the residual energy of network is nearly zero when the network lifetime ends. Therefore, our research can give a significant guidance on the optimization of wireless sensor networks.


communications and mobile computing | 2009

Improved Analysis of Energy Hole for Wireless Sensor Networks

Zeng Zhi-wen; Liu An-feng; Chen Zhi-gang; Wu Xian-you; Long Jun

Through analysis of energy consumption of wireless sensor networks with uniform node distribution, this paper finds that energy hole in the wireless sensor networks with uniform node distribution can not be avoided. When network lifetime ends, as much as 90% of network energy remains. However, network lifetime can increase several times by selecting different transmission power levels. The main conclusions in this paper are presented is that the energy consumption in the same circular ring is nonuniform if the density of sensor nodes in the same circular ring is uniform.


Journal of Central South University of Technology | 2007

New multicast scheme based on Dynamic mobility prediction in mobile IPv6 environment

Huang Guo-sheng; Chen Zhi-gang; Zhao Ming; Wang Lu-lu (王路露); Huo Ying (霍英); Liu An-feng

A new mobile multicast scheme called mobility prediction based mobile multicast(MPBMM) was proposed. In MPBMM, when a mobile node (MN) roams among subnets during a multicast session, MN predicts the next subnet, to which MN will attach, by the information of its position and mobility speed, consequently speeds up the handoff procedure. Simulation results show that the proposed scheme can minimize the loss of multicast packets, reduce the delay of subnet handoff, decrease the frequency of multicast tree reconfiguration, and optimize the delivery path of multicast packets. When MN moves among subnets at different speeds (from 5 to 25 m/s), the maximum loss ratio of multicast packets is less than0.2%, the maximum inter-arrival time of multicast packets is 117 ms, so the proposed scheme can meet the QoS requirements of real-time services. In addition, MPBMM can support the mobility of multicast source.


Wuhan University Journal of Natural Sciences | 2005

Research on fault tolerant scheduling algorithms of web cluster based on probability

Liu An-feng; Chen Zhi-gang; Long Guo-ping

Aiming at the soft real-time fault tolerant demand of critical web applications at present, such as E-commerce, a new fault tolerant scheduling algorithm based on probability is proposed. To achieve fault tolerant scheduling, the primary/slave backup technology is applied on the basis of tasks self similar accessing characteristics, when the primary task completed successfully, the resources allocated for the slave task are reclaimed, thus advancing systems efficiency. Experimental results demonstrate on the premise of satisfying systems certain fault tolerant probability, tasks schedulabilistic probability is improved, especially, the higher tasks self similar degree is, the more obviously the utilization of system resources is enhanced.


Journal of Central South University of Technology | 2005

Heuristic file sorted assignment algorithm of parallel I/O on cluster computing system

Chen Zhi-gang; Zeng Bi-qing; Xiong Ce; Deng Xiaoheng; Zeng Zhi-wen; Liu An-feng

A new file assignment strategy of parallel I/O, which is named heuristic file sorted assignment algorithm was proposed on cluster computing system. Based on the load balancing, it assigns the files to the same disk according to the similar service time. Firstly, the files were sorted and stored at the set I in descending order in terms of their service time, then one disk of cluster node was selected randomly when the files were to be assigned, and at last the continuous files were taken orderly from the set I to the disk until the disk reached its load maximum. The experimental results show that the new strategy improves the performance by 20.2% when the load of the system is light and by 31.6% when the load is heavy. And the higher the data access rate, the more evident the improvement of the performance obtained by the heuristic file sorted assignment algorithm.


Wuhan University Journal of Natural Sciences | 2004

A new self-adapting admission control algorithm for differential service in Web clusters

Liu An-feng; Chen Zhi-gang; Long Guo-ping

A new admission control algorithm considering the network self-similar access characteristics is proposed. Taking advantage of the mathematical model of the network traffic admission control which can effectively overcome the self-similar characteristics of the network requests, through the scheduling of the differential service qucue based on priority while at the same time taking into account various factors including access characteristics of requests, load information, etc, smoothness of the admission control is ensured by the algorithm proposed in this paper. We design a non-linear self-adapting control algorithm by introducing an exponential admission function, thus overcomes the negative aspects introduced by static threshold parameters. Simulation results show that the scheme proposed in this paper can effectively improve the resource utilization of the clusters, while at the same time protecting the service with high priority. Our simulation results also show that this algorithm can improve system stability and reliability too.


Computer Engineering | 2012

WSN Routing Experimental Teaching Platform Based on Omnet

Liu An-feng; Ren Ju; Chen Zhi-gang


Journal of Communications | 2010

Trust-sensitive Web service composition strategy based on black and white board

Liu An-feng


Archive | 2015

Wireless Mesh intelligent power grid routing mechanism with QoS perceiving and loading balancing

Deng Xiaoheng; He Lifang; Liu An-feng; Gui Jinsong; Zeng Zhi-wen; Qi Huamei

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Chen Zhi-gang

Central South University

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Zeng Zhi-wen

Central South University

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Deng Xiaoheng

Central South University

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Gui Weihua

Central South University

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Long Guo-ping

Central South University

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Wu Xian-you

Central South University

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Xiong Ce

Central South University

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He Hui

Central South University

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