Active Queue Management (AQM) is an active research area in the Internet community. Random Early Detection (RED) is a typical AQM algorithm, but it is known that it is difficult to configure its parameters and its ave...Active Queue Management (AQM) is an active research area in the Internet community. Random Early Detection (RED) is a typical AQM algorithm, but it is known that it is difficult to configure its parameters and its average queue length is closely related to the load level. This paper proposes an effective fuzzy congestion control algorithm based on fuzzy logic which uses the pre- dominance of fuzzy logic to deal with uncertain events. The main advantage of this new congestion control algorithm is that it discards the packet dropping mechanism of RED, and calculates packet loss according to a preconfigured fuzzy logic by using the queue length and the buffer usage ratio. Theo- retical analysis and Network Simulator (NS) simulation results show that the proposed algorithm achieves more throughput and more stable queue length than traditional schemes. It really improves a router's ability in network congestion control in IP network.展开更多
A novel cationic Pt(Ⅱ)complex 2 with 2-(2,4-difluorophenyl)pyridine as the cyclometalating ligand and 1,10-phenanthroline as the auxiliary ligand has been synthesized and fully characterized.This complex exhibits muc...A novel cationic Pt(Ⅱ)complex 2 with 2-(2,4-difluorophenyl)pyridine as the cyclometalating ligand and 1,10-phenanthroline as the auxiliary ligand has been synthesized and fully characterized.This complex exhibits much higher aggregation-induced phosphorescent emission activity than that of a nonfluorinated complex 1 in CH_(3)CN/H_(2)O.The complex 2 demonstrates efficient detection on picric acid(PA)in CH_(3)CN/H_(2)O,providing a high quenching constant(K_(SV)=2.3×10^(4) L/mol)and a low limit of detection(LOD=0.26μmol/L).In addition,complex 2 shows high selectivity for detection of PA in real water samples.Density functional theory calculations and proton nuclear magnetic resonance spectra suggest that the detection mechanism is attributed to the photo-induced electron transfer.展开更多
By applying the method of average and variance, a new queue management algorithm named the Classified-Random Early Detection （CRED） algorithm is presented which can identify the media streaming, TCP traffic and othe...By applying the method of average and variance, a new queue management algorithm named the Classified-Random Early Detection （CRED） algorithm is presented which can identify the media streaming, TCP traffic and other UDP traffic at the edge routers. The algorithm discriminates the slow start and the congestion control phase of the TCP traffic and combines the TCP congestion control with the IP congestion control to alleviate the congestion effectively. Simulation shows that CRED can not only make the media streaming obtain the resources needed but also protect the TCP traffic transmitted effectively and reliably.展开更多
Based on the linearized model of the TCP connections through the congested routers, this paper puts forward an active queue management algorithm (FVS-T). The algorithm utilizes the fuzzy variable structure control alg...Based on the linearized model of the TCP connections through the congested routers, this paper puts forward an active queue management algorithm (FVS-T). The algorithm utilizes the fuzzy variable structure control algorithm with delay factor to compensate time varying round-trip times (RTT) and uncertainties with respect to the number of active TCP sessions. By analyzing the robustness and performance of the control scheme for the nonlinear TCP/AQM model, we show that the proposed design has good performance and robustness, which are central to the notion of AQM. Implementation issues were discussed and ns simulations were provided to validate the design and compare its performance to other peer schemes in different scenarios. The results show that the proposed design significantly outperforms the other congestion schemes in terms of packet loss ratio, throughput and buffer fluctuation.展开更多
In recent years, because the number of the computers in the Internet has been increasing, it is important for network accounting, network safe management and network flow measurement to see the behavior of the activat...In recent years, because the number of the computers in the Internet has been increasing, it is important for network accounting, network safe management and network flow measurement to see the behavior of the activated IP flow. In the paper, we research almost 30TB traffic trace that all traffic entered into and removed from the CERNET Eastern China (north) regional network in Feb. 2001. And we analyze the active degree of IP in the regional network. The research result indicate that the statistics of in-IP flow, out-IP flow and IP flow are heavytailed and the ratio of in-IP flow and out-IP flow have the character of log-normal distribution. According to these characters, we make the model of pareto distribution and log-normal distribution and propose the way that evaluate these distribution models.展开更多
基金Supported by the National High Technology Research and Development of China (863 Program) (No.2003AA121560)the High Technology Research and Development Program of Jiangsu Province (No.BEG2003001).
文摘Active Queue Management (AQM) is an active research area in the Internet community. Random Early Detection (RED) is a typical AQM algorithm, but it is known that it is difficult to configure its parameters and its average queue length is closely related to the load level. This paper proposes an effective fuzzy congestion control algorithm based on fuzzy logic which uses the pre- dominance of fuzzy logic to deal with uncertain events. The main advantage of this new congestion control algorithm is that it discards the packet dropping mechanism of RED, and calculates packet loss according to a preconfigured fuzzy logic by using the queue length and the buffer usage ratio. Theo- retical analysis and Network Simulator (NS) simulation results show that the proposed algorithm achieves more throughput and more stable queue length than traditional schemes. It really improves a router's ability in network congestion control in IP network.
基金financial support from the National Natural Science Foundation of China(No.21978042)the Fundamental Research Funds for the Central Universities(No.DUT22LAB610).
文摘A novel cationic Pt(Ⅱ)complex 2 with 2-(2,4-difluorophenyl)pyridine as the cyclometalating ligand and 1,10-phenanthroline as the auxiliary ligand has been synthesized and fully characterized.This complex exhibits much higher aggregation-induced phosphorescent emission activity than that of a nonfluorinated complex 1 in CH_(3)CN/H_(2)O.The complex 2 demonstrates efficient detection on picric acid(PA)in CH_(3)CN/H_(2)O,providing a high quenching constant(K_(SV)=2.3×10^(4) L/mol)and a low limit of detection(LOD=0.26μmol/L).In addition,complex 2 shows high selectivity for detection of PA in real water samples.Density functional theory calculations and proton nuclear magnetic resonance spectra suggest that the detection mechanism is attributed to the photo-induced electron transfer.
基金This paper is supported by the Foundation of Science and Technology Development of Shaanxi Province.
文摘By applying the method of average and variance, a new queue management algorithm named the Classified-Random Early Detection （CRED） algorithm is presented which can identify the media streaming, TCP traffic and other UDP traffic at the edge routers. The algorithm discriminates the slow start and the congestion control phase of the TCP traffic and combines the TCP congestion control with the IP congestion control to alleviate the congestion effectively. Simulation shows that CRED can not only make the media streaming obtain the resources needed but also protect the TCP traffic transmitted effectively and reliably.
文摘Based on the linearized model of the TCP connections through the congested routers, this paper puts forward an active queue management algorithm (FVS-T). The algorithm utilizes the fuzzy variable structure control algorithm with delay factor to compensate time varying round-trip times (RTT) and uncertainties with respect to the number of active TCP sessions. By analyzing the robustness and performance of the control scheme for the nonlinear TCP/AQM model, we show that the proposed design has good performance and robustness, which are central to the notion of AQM. Implementation issues were discussed and ns simulations were provided to validate the design and compare its performance to other peer schemes in different scenarios. The results show that the proposed design significantly outperforms the other congestion schemes in terms of packet loss ratio, throughput and buffer fluctuation.
文摘In recent years, because the number of the computers in the Internet has been increasing, it is important for network accounting, network safe management and network flow measurement to see the behavior of the activated IP flow. In the paper, we research almost 30TB traffic trace that all traffic entered into and removed from the CERNET Eastern China (north) regional network in Feb. 2001. And we analyze the active degree of IP in the regional network. The research result indicate that the statistics of in-IP flow, out-IP flow and IP flow are heavytailed and the ratio of in-IP flow and out-IP flow have the character of log-normal distribution. According to these characters, we make the model of pareto distribution and log-normal distribution and propose the way that evaluate these distribution models.
