To cope with the problem of low protocol efficiency of the standard ad hoc on-demand distance vector （AODV） routing protocol with the periodic Hello message broadcast mechanism, a new link availability prediction ba...To cope with the problem of low protocol efficiency of the standard ad hoc on-demand distance vector （AODV） routing protocol with the periodic Hello message broadcast mechanism, a new link availability prediction based strategy is introduced to reduce the amount of Hello messages. In this strategy, a novel wireless link availability prediction model under line-of-sight （LOS） propagation environments is proposed based on which the parameter of Hello Interval in AODV can be dynamically adjusted to achieve the goal of changing the frequency of Hello message broadcasts under different link stability degrees. Simulation results demonstrate that, compared with the standard AODV with the periodic Hello message broadcast mechanism, the proposed protocol effectively reduces unnecessary control message overhead and greatly improves the performance in terms of end-to-end delay and efficiency.展开更多
Dynamic latency over the Intemet is an Important parameter for evaluating the performance of Web service orchestration. In this paper, we propose a performance analyzing and correctness checking method for service orc...Dynamic latency over the Intemet is an Important parameter for evaluating the performance of Web service orchestration. In this paper, we propose a performance analyzing and correctness checking method for service orchestration with dynamic latency simulated in Colored PetriNets （CPNs）. First, we extend the CPN to Web Service Composition Orchestration Network System （WS-CONS） for the description of dynamic latency in service orchestration. Secondly, with simulated dynamic latency, a buffer-limited policy and admittance-control policy are designed in WS- CONS and implemented on CPN Tools. In the buffer-limited policy, the passing messages would be discarded if the node capacity is not adequate. In the admittance-control policy, the ability of a message entering the system depends on the number of messages concurrently flowing in the system. This helps to enhance the success rate of message passing. Finally, the system performance is evaluated through running models in CPN Tools. Simulated results show that the dynamic latency plays an important role in the system throughput and response latency. This simulation helps system designers to quickly make proper compromises at low cost.展开更多
We study the influence of screening effect on quantum decoherence for charge qubit and the process of quantum information storage. When the flux produced by the circulating current in SQUID loop is considered, screeni...We study the influence of screening effect on quantum decoherence for charge qubit and the process of quantum information storage. When the flux produced by the circulating current in SQUID loop is considered, screening effect is formally characterized by a LC resonator. Using large-detuning condition and Fr6hlich transformation in the qubit-cavity-resonator system, we calculate the decoherenee factor for charge qubit and the effective qubit-cavity Hamiltonian. The decoherence factor owns a factorized structure, it shows that screening effect is a resource of decoherence for charge qubit. The effective Hamiltonian shows that the screening effect results in a frequency shift for charge qubit and a modified qubit-cavity coupling constant induced by a LC resonator.展开更多
基金The National High Technology Research and Development Program of China (863Program)(No2006AA01Z268)
文摘To cope with the problem of low protocol efficiency of the standard ad hoc on-demand distance vector （AODV） routing protocol with the periodic Hello message broadcast mechanism, a new link availability prediction based strategy is introduced to reduce the amount of Hello messages. In this strategy, a novel wireless link availability prediction model under line-of-sight （LOS） propagation environments is proposed based on which the parameter of Hello Interval in AODV can be dynamically adjusted to achieve the goal of changing the frequency of Hello message broadcasts under different link stability degrees. Simulation results demonstrate that, compared with the standard AODV with the periodic Hello message broadcast mechanism, the proposed protocol effectively reduces unnecessary control message overhead and greatly improves the performance in terms of end-to-end delay and efficiency.
基金This paper was supported by the National Natural Science Foundation of China under Grants No.61170053,No.61101214,No.61100205，the National High-Tech Research and Development Plan of China under Grant No.2012AA010902-1，the Natural Science Foundation of Beijing under Grant No.4112027，Special Project of National CAS Union-The High Performace Cloud Service Platform for Enterprise Creative Computing
文摘Dynamic latency over the Intemet is an Important parameter for evaluating the performance of Web service orchestration. In this paper, we propose a performance analyzing and correctness checking method for service orchestration with dynamic latency simulated in Colored PetriNets （CPNs）. First, we extend the CPN to Web Service Composition Orchestration Network System （WS-CONS） for the description of dynamic latency in service orchestration. Secondly, with simulated dynamic latency, a buffer-limited policy and admittance-control policy are designed in WS- CONS and implemented on CPN Tools. In the buffer-limited policy, the passing messages would be discarded if the node capacity is not adequate. In the admittance-control policy, the ability of a message entering the system depends on the number of messages concurrently flowing in the system. This helps to enhance the success rate of message passing. Finally, the system performance is evaluated through running models in CPN Tools. Simulated results show that the dynamic latency plays an important role in the system throughput and response latency. This simulation helps system designers to quickly make proper compromises at low cost.
基金Supported by National Natural Science Foundation of China under Grant Nos. 0547101 and 10604002
文摘We study the influence of screening effect on quantum decoherence for charge qubit and the process of quantum information storage. When the flux produced by the circulating current in SQUID loop is considered, screening effect is formally characterized by a LC resonator. Using large-detuning condition and Fr6hlich transformation in the qubit-cavity-resonator system, we calculate the decoherenee factor for charge qubit and the effective qubit-cavity Hamiltonian. The decoherence factor owns a factorized structure, it shows that screening effect is a resource of decoherence for charge qubit. The effective Hamiltonian shows that the screening effect results in a frequency shift for charge qubit and a modified qubit-cavity coupling constant induced by a LC resonator.
