Background:Recent developments in virtual acoustic technology has levered promising applications in the field of auditory sciences,especially in spatial perception.While conventional auditory spatial assessment using ...Background:Recent developments in virtual acoustic technology has levered promising applications in the field of auditory sciences,especially in spatial perception.While conventional auditory spatial assessment using loudspeakers,interaural differences and/or questionnaires are limited by the availability and cost of instruments,the use of virtual acoustic space identification(VASI)test has widespread applications in spatial test battery as it overcomes these constraints.Purpose:The lack of test-retest reliability data of VASI test narrows its direct application in auditory spatial assessment,which is explored in the present study.Methods:Data from 75 normal-hearing young adults(mean age:25.11 y±4.65 SD)was collected in three sessions:baseline,within 15 min of baseline(intra-session),and one week after baseline session(inter-session).Test-retest reliability was assessed using the intra-class correlation coefficient(ICC),coefficient of variation(CV),and cluster plots.Results:The results showed excellent reliability for both accuracy and reaction time measures of VASI,with ICC values of 0.93 and 0.87,respectively.The CV values for overall VASI accuracy and reaction time 9.66% and 11.88%,respectively.This was also complemented by the cluster plot analyses,which showed 93.33% and 96.00% of temporal stability in the accuracy and reaction time measures,indicative of high test-retest reliability of VASI test in auditory spatial assessment.Conclusions:The high temporal stability(test-retest reliability)of VASI test validates its application in spatial hearing test battery.展开更多
Recent researches show that inter-session network coding could decrease the number of packets transmission and achieve higher throughput in wireless network compared with traditional forwarding mechanism. In most exis...Recent researches show that inter-session network coding could decrease the number of packets transmission and achieve higher throughput in wireless network compared with traditional forwarding mechanism. In most existing relay mechanisms based on inter-session network such as COPE, relay node demands to collect the messages from its neighbor nodes to get notice of which packets already overheard by them so as to determine whether there exists coding opportunity between or among forwarding packets. However, transmission overhead of this message collection and computing cost of opportunity determination will degrade the performance of these mechanisms. It is observed that coding opportunity at relay node is much more related with the local topology, and the opportunity of encoding three or more packets together is far less than that of encoding two packets together in wireless network with general density. Based on this, a new coding-aware routing mechanism, named TCAR, is proposed. TCAR ignores the oppommity of encoding three or more than three packets together. Each relay node maintains an encoding mapping table being established according to the result of its local topology detection, which can be used to calculate the path cost during routing setup phase, and determine that which two packets can be encoded together during the packets forwarding phase. In TCAR, instead of periodic messages collection, each relay nodes just need once local topology detection, and the encoding determination is much simpler than that of the former mechanisms. Simulation results show that compared with typical inter-session network coding mechanisms COPE and COPE-based routing, TCAR achieves 12% and 7% throughput gains, and keeps the minimum end to end delay.展开更多
To maximize the aggregate throughput achieved in heterogeneous networks, this paper investigates inter-session network coding for the distribution of layered source data. We define inter-layer hierarchical random line...To maximize the aggregate throughput achieved in heterogeneous networks, this paper investigates inter-session network coding for the distribution of layered source data. We define inter-layer hierarchical random linear network codes （IHRLNC）, which not only take the flexibility of intersession network coding for layer mixing but also consider the strict priority inherent in the layered source data. Furthermore, we propose the inter-layer hierarchical multicast （IHM）, which performs IHRLNC in the network such that each sink can recover some source layers according to its individu- al capacity. To determine the optimal type of IHRLNC that should be performed on each edge in IHM, we formulate an optimization problem based on 0-1 integer linear programming, and propose a heuristic approach to approximate the optimal solution in polynomial time. Simulation results show that the proposed IHM can achieve throughput gains over the layered muhicast schemes.展开更多
The border gateway protocol (BGP) is the default inter domain routing protocol used on the internet for exchanging information between autonomous systems. Available literature suggests that BGP is vulnerable to sessio...The border gateway protocol (BGP) is the default inter domain routing protocol used on the internet for exchanging information between autonomous systems. Available literature suggests that BGP is vulnerable to session hijacking attacks. There are a number of proposals aimed at improving BGP security which have not been fully implemented. This paper examines a number of approaches for securing BGP through a comparative study and identifies the reasons why these proposals have not been implemented commercially. This paper analyses the architecture of internet routing and the design of BGP while focusing on the problem of BGP session hijacking attacks. Using Graphical Network Simulator 3 (GNS-3), a session hijack is demonstrated and a solution which involves the implementation of route filtering, policy-maps and route-maps on CISCO routers representing ASes is carried out. In the end, a workable industry standard framework for securing and protecting BGP sessions and border routers from exploitation with little or no modification to the existing routing infrastructure is demonstrated.展开更多
文摘Background:Recent developments in virtual acoustic technology has levered promising applications in the field of auditory sciences,especially in spatial perception.While conventional auditory spatial assessment using loudspeakers,interaural differences and/or questionnaires are limited by the availability and cost of instruments,the use of virtual acoustic space identification(VASI)test has widespread applications in spatial test battery as it overcomes these constraints.Purpose:The lack of test-retest reliability data of VASI test narrows its direct application in auditory spatial assessment,which is explored in the present study.Methods:Data from 75 normal-hearing young adults(mean age:25.11 y±4.65 SD)was collected in three sessions:baseline,within 15 min of baseline(intra-session),and one week after baseline session(inter-session).Test-retest reliability was assessed using the intra-class correlation coefficient(ICC),coefficient of variation(CV),and cluster plots.Results:The results showed excellent reliability for both accuracy and reaction time measures of VASI,with ICC values of 0.93 and 0.87,respectively.The CV values for overall VASI accuracy and reaction time 9.66% and 11.88%,respectively.This was also complemented by the cluster plot analyses,which showed 93.33% and 96.00% of temporal stability in the accuracy and reaction time measures,indicative of high test-retest reliability of VASI test in auditory spatial assessment.Conclusions:The high temporal stability(test-retest reliability)of VASI test validates its application in spatial hearing test battery.
基金Projects(61173169,61106036)supported by the National Natural Science Foundation of ChinaProject(NCET-10-0798)Program for New Century Excellent Talents in University,China
文摘Recent researches show that inter-session network coding could decrease the number of packets transmission and achieve higher throughput in wireless network compared with traditional forwarding mechanism. In most existing relay mechanisms based on inter-session network such as COPE, relay node demands to collect the messages from its neighbor nodes to get notice of which packets already overheard by them so as to determine whether there exists coding opportunity between or among forwarding packets. However, transmission overhead of this message collection and computing cost of opportunity determination will degrade the performance of these mechanisms. It is observed that coding opportunity at relay node is much more related with the local topology, and the opportunity of encoding three or more packets together is far less than that of encoding two packets together in wireless network with general density. Based on this, a new coding-aware routing mechanism, named TCAR, is proposed. TCAR ignores the oppommity of encoding three or more than three packets together. Each relay node maintains an encoding mapping table being established according to the result of its local topology detection, which can be used to calculate the path cost during routing setup phase, and determine that which two packets can be encoded together during the packets forwarding phase. In TCAR, instead of periodic messages collection, each relay nodes just need once local topology detection, and the encoding determination is much simpler than that of the former mechanisms. Simulation results show that compared with typical inter-session network coding mechanisms COPE and COPE-based routing, TCAR achieves 12% and 7% throughput gains, and keeps the minimum end to end delay.
基金Supported by the National Natural Science Foundation of China （ No. 60832001 ）.
文摘To maximize the aggregate throughput achieved in heterogeneous networks, this paper investigates inter-session network coding for the distribution of layered source data. We define inter-layer hierarchical random linear network codes （IHRLNC）, which not only take the flexibility of intersession network coding for layer mixing but also consider the strict priority inherent in the layered source data. Furthermore, we propose the inter-layer hierarchical multicast （IHM）, which performs IHRLNC in the network such that each sink can recover some source layers according to its individu- al capacity. To determine the optimal type of IHRLNC that should be performed on each edge in IHM, we formulate an optimization problem based on 0-1 integer linear programming, and propose a heuristic approach to approximate the optimal solution in polynomial time. Simulation results show that the proposed IHM can achieve throughput gains over the layered muhicast schemes.
文摘The border gateway protocol (BGP) is the default inter domain routing protocol used on the internet for exchanging information between autonomous systems. Available literature suggests that BGP is vulnerable to session hijacking attacks. There are a number of proposals aimed at improving BGP security which have not been fully implemented. This paper examines a number of approaches for securing BGP through a comparative study and identifies the reasons why these proposals have not been implemented commercially. This paper analyses the architecture of internet routing and the design of BGP while focusing on the problem of BGP session hijacking attacks. Using Graphical Network Simulator 3 (GNS-3), a session hijack is demonstrated and a solution which involves the implementation of route filtering, policy-maps and route-maps on CISCO routers representing ASes is carried out. In the end, a workable industry standard framework for securing and protecting BGP sessions and border routers from exploitation with little or no modification to the existing routing infrastructure is demonstrated.
