The filter-based reactive packet filtering is a key technology in attack traffic filtering for defending against the Denial-of- Service （DOS） attacks. Two kinds of relevant schemes have been proposed as victim- end ...The filter-based reactive packet filtering is a key technology in attack traffic filtering for defending against the Denial-of- Service （DOS） attacks. Two kinds of relevant schemes have been proposed as victim- end filtering and source-end filtering. The first scheme prevents attack traffic from reaching the victim, but causes the huge loss of legitimate flows due to the scarce filters （termed as collateral damages）; the other extreme scheme can obtain the sufficient filters, but severely degrades the network transmission performance due to the abused filtering routers. In this paper, we propose a router based packet filtering scheme, which provides relatively more filters while reducing the quantity of filtering touters. We implement this scheme on the emulated DoS scenarios based on the synthetic and real-world Internet topologies. Our evaluation results show that compared to the previous work, our scheme just uses 20% of its filtering routers, but only increasing less than 15 percent of its collateral damage.展开更多
The key problem in unstructured P2P system is how to control "Flood".Some studies focus on constructing more efficient topology while others focus on better query algorithms.This paper presents HICUS(Hierarc...The key problem in unstructured P2P system is how to control "Flood".Some studies focus on constructing more efficient topology while others focus on better query algorithms.This paper presents HICUS(Hierarchical Interest-driven Community-based Unstructured System) motivated by a basic thought-whether the resources correlate with topology distinguishes structured and unstruc-tured P2P essentially.By introducing hierarchical "interest",HICUS organizes a quasi-structured topology through a pure distributed way,and provides a new platform for query algorithms.We study the procedure and performance of topology organization,and the simulations show that HICUS forms a small-world which can significantly improve the routing efficiency.展开更多
This paper carries out a systematic investigation into the bisimulation lattice of asymmetric chi calculus with a mismatch combinator. It is shown that all the sixty three L bisimilarities collapse to twelve distinct ...This paper carries out a systematic investigation into the bisimulation lattice of asymmetric chi calculus with a mismatch combinator. It is shown that all the sixty three L bisimilarities collapse to twelve distinct relations and they form a bisimulation lattice with respect to set inclusion. The top of the lattice coincides with the barbed bisimilarity.展开更多
In recent years, the development of mobile equipment makes the topology of the network to change rapidly. So that its routing problem an important research subject accordingly. In all the proposed protocols, the Ad H...In recent years, the development of mobile equipment makes the topology of the network to change rapidly. So that its routing problem an important research subject accordingly. In all the proposed protocols, the Ad Hoc On-demand Distance Vector Routing Protocol（AODV） is applied to most wireless environments. With it, the shortest path from the source to destination node is chosen by the metric of hop counts. However, the chosen path with this metric may not be a stable one. With the research of predecessors, the Link Available Time（LAT ） can be calculated by the strength of received signal and may be regarded as another usable routing metric. Based on that, the authors develop a protocol named AODV-Deleting Path with Bad Broken Index （AODV-DPWBB） and discuss all the logicality of it. The simulation is done for two contention modes in several node speeds with discussion followed. The simulation result shows better throughput, and end-to-end delay can be obtained comparing the original AODV with metric of hop-count.展开更多
Cascaded H-Bridge inverter has been researched for the past two decades, but there are no explicit guidelines on how one can realize a cascaded NPC （neutral-point-clamped）/H-Bridge inverter. Past research has also c...Cascaded H-Bridge inverter has been researched for the past two decades, but there are no explicit guidelines on how one can realize a cascaded NPC （neutral-point-clamped）/H-Bridge inverter. Past research has also concentrated on realizing a five-level NPC/H-Bridge inverter. This fails to address the principle of realizing a general cascaded N-level NPC/H-Bridge PWM inverter. This paper proposes an improved topology for achieving a nine-level cascaded NPC （neutral-point-clamped） H-Bridge inverter with reduced harmonic content. This new proposed topology requires a lesser number of separate dc sources as compared to conventional cascaded H-Bridge inverter. The whole system is considered as having four three level legs having two positive and two negative legs. By properly phase shifting the modulating wave and carriers, a nine-level output is achieved. A theoretical harmonic analysis of the proposed inverter is carried out based on double Fourier principle. The theoretical results are verified through MATLAB simulation.展开更多
基金supported in part by the funding agencies of china:the Doctoral Fund of Northeastern University of Qinhuangdao(Grant No.XNB201410)the Fundamental Research Funds for the Central Universities(Grant No.N130323005)
文摘The filter-based reactive packet filtering is a key technology in attack traffic filtering for defending against the Denial-of- Service （DOS） attacks. Two kinds of relevant schemes have been proposed as victim- end filtering and source-end filtering. The first scheme prevents attack traffic from reaching the victim, but causes the huge loss of legitimate flows due to the scarce filters （termed as collateral damages）; the other extreme scheme can obtain the sufficient filters, but severely degrades the network transmission performance due to the abused filtering routers. In this paper, we propose a router based packet filtering scheme, which provides relatively more filters while reducing the quantity of filtering touters. We implement this scheme on the emulated DoS scenarios based on the synthetic and real-world Internet topologies. Our evaluation results show that compared to the previous work, our scheme just uses 20% of its filtering routers, but only increasing less than 15 percent of its collateral damage.
基金Supported by the National Natural Science Foundation of China (No.60602018 and 60772033)
文摘The key problem in unstructured P2P system is how to control "Flood".Some studies focus on constructing more efficient topology while others focus on better query algorithms.This paper presents HICUS(Hierarchical Interest-driven Community-based Unstructured System) motivated by a basic thought-whether the resources correlate with topology distinguishes structured and unstruc-tured P2P essentially.By introducing hierarchical "interest",HICUS organizes a quasi-structured topology through a pure distributed way,and provides a new platform for query algorithms.We study the procedure and performance of topology organization,and the simulations show that HICUS forms a small-world which can significantly improve the routing efficiency.
文摘This paper carries out a systematic investigation into the bisimulation lattice of asymmetric chi calculus with a mismatch combinator. It is shown that all the sixty three L bisimilarities collapse to twelve distinct relations and they form a bisimulation lattice with respect to set inclusion. The top of the lattice coincides with the barbed bisimilarity.
基金supported by National Taiwan University of Science and Technology
文摘In recent years, the development of mobile equipment makes the topology of the network to change rapidly. So that its routing problem an important research subject accordingly. In all the proposed protocols, the Ad Hoc On-demand Distance Vector Routing Protocol（AODV） is applied to most wireless environments. With it, the shortest path from the source to destination node is chosen by the metric of hop counts. However, the chosen path with this metric may not be a stable one. With the research of predecessors, the Link Available Time（LAT ） can be calculated by the strength of received signal and may be regarded as another usable routing metric. Based on that, the authors develop a protocol named AODV-Deleting Path with Bad Broken Index （AODV-DPWBB） and discuss all the logicality of it. The simulation is done for two contention modes in several node speeds with discussion followed. The simulation result shows better throughput, and end-to-end delay can be obtained comparing the original AODV with metric of hop-count.
文摘Cascaded H-Bridge inverter has been researched for the past two decades, but there are no explicit guidelines on how one can realize a cascaded NPC （neutral-point-clamped）/H-Bridge inverter. Past research has also concentrated on realizing a five-level NPC/H-Bridge inverter. This fails to address the principle of realizing a general cascaded N-level NPC/H-Bridge PWM inverter. This paper proposes an improved topology for achieving a nine-level cascaded NPC （neutral-point-clamped） H-Bridge inverter with reduced harmonic content. This new proposed topology requires a lesser number of separate dc sources as compared to conventional cascaded H-Bridge inverter. The whole system is considered as having four three level legs having two positive and two negative legs. By properly phase shifting the modulating wave and carriers, a nine-level output is achieved. A theoretical harmonic analysis of the proposed inverter is carried out based on double Fourier principle. The theoretical results are verified through MATLAB simulation.
