随着软件定义联网(Software Defined Networking,SDN)的不断发展,SDN网络的需求和服务不断扩大。SDN控制器作为全网的控制和管理中心,承受着巨大的业务需求压力,极易造成SDN控制器的瘫痪和故障,出现服务中断等不利影响。同时,单个管理...随着软件定义联网(Software Defined Networking,SDN)的不断发展,SDN网络的需求和服务不断扩大。SDN控制器作为全网的控制和管理中心,承受着巨大的业务需求压力,极易造成SDN控制器的瘫痪和故障,出现服务中断等不利影响。同时,单个管理域所呈现的局限性也越来越大。为了解决SDN控制器瘫痪和故障造成的严重后果,克服单个管理域的局限性,在多管理域场景下,根据监测到的SDN控制器故障结果提出具体可行的控制器故障恢复的解决方案。为此,提出了基于Open Flow消息进行SDN控制器故障监测的方法,研究了控制平面的多控制器部署问题,讨论了多控制器的同步机制,搭建主备控制器模型用于实现交换机迁移,根据域内和域间不同的应用场景,采用了不同的故障恢复策略。采用交换机迁移的最小代价原则选取备用控制器,实现故障恢复。测试结果表明,多管理域场景下对故障控制器执行不同的故障恢复策略可以实现对SDN控制器的故障恢复。展开更多
In situ pressure-preserved coring(IPP-Coring)technology is considered one of the most efficient methods for assessing resources.However,seal failure caused by the rotation of pressure controllers greatly affects the s...In situ pressure-preserved coring(IPP-Coring)technology is considered one of the most efficient methods for assessing resources.However,seal failure caused by the rotation of pressure controllers greatly affects the success of pressure coring.In this paper,a novel spherical-cylindrical shell pressure controller was proposed.The finite element analysis model was used to analyze the stress distribution and deformation characteristics of the pressure controller at different rotation angles.The seal failure mechanism caused by the rotation of the pressure controller was discussed.The stress deviation rate was defined to quantitatively characterize the stress concentration.Based on the test equipment designed in this laboratory,the ultimate bearing strength of the pressure controller was tested.The results show that the rotation of the valve cover causes an increase in the deformation on its lower side.Furthermore,the specific sealing pressure in the weak zone is greatly reduced by a statistically significant amount,resulting in seal failure.When the valve cover rotates 5°around the major axis,the stress deviation rate is-92.6%.To prevent rotating failure of the pressure controller,it is necessary to control the rotation angle of the valve cover within 1°around the major axis.The results of this research can help engineers reduce failure-related accidents,provide countermeasures for pressure coring,and contribute to the exploration and evaluation of deep oil and gas resources.展开更多
In this letter, a distributed protocol for sampled-data synchronization of coupled harmonic oscillators with controller failure and communication delays is proposed, and a brief procedure of convergence analysis for s...In this letter, a distributed protocol for sampled-data synchronization of coupled harmonic oscillators with controller failure and communication delays is proposed, and a brief procedure of convergence analysis for such algorithm over undirected connected graphs is provided. Furthermore, a simple yet generic criterion is also presented to guarantee synchronized oscillatory motions in coupled harmonic oscillators. Subsequently, the simulation results are worked out to demonstrate the efficiency and feasibility of the theoretical results.展开更多
针对软件定义网络(software defined network,SDN)中控制器发生故障问题,提出了一种基于多种群粒子群算法的SDN控制器故障恢复策略。从其他正常工作的子控制器集合中挑选出能够容纳失控交换机负载的备份控制器集,将精英种群与子种群组...针对软件定义网络(software defined network,SDN)中控制器发生故障问题,提出了一种基于多种群粒子群算法的SDN控制器故障恢复策略。从其他正常工作的子控制器集合中挑选出能够容纳失控交换机负载的备份控制器集,将精英种群与子种群组成多种群粒子群,采用预选和交互机制演化出备份控制器的最优位置,以保证交换机与控制器之间的传播时延最小,完成失控交换机的迁移。实验结果表明,相比于现有的控制器故障恢复算法,该算法在恢复时间、控制器负载利用方面均有所提升。展开更多
文摘随着软件定义联网(Software Defined Networking,SDN)的不断发展,SDN网络的需求和服务不断扩大。SDN控制器作为全网的控制和管理中心,承受着巨大的业务需求压力,极易造成SDN控制器的瘫痪和故障,出现服务中断等不利影响。同时,单个管理域所呈现的局限性也越来越大。为了解决SDN控制器瘫痪和故障造成的严重后果,克服单个管理域的局限性,在多管理域场景下,根据监测到的SDN控制器故障结果提出具体可行的控制器故障恢复的解决方案。为此,提出了基于Open Flow消息进行SDN控制器故障监测的方法,研究了控制平面的多控制器部署问题,讨论了多控制器的同步机制,搭建主备控制器模型用于实现交换机迁移,根据域内和域间不同的应用场景,采用了不同的故障恢复策略。采用交换机迁移的最小代价原则选取备用控制器,实现故障恢复。测试结果表明,多管理域场景下对故障控制器执行不同的故障恢复策略可以实现对SDN控制器的故障恢复。
基金supported by the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315)National Natural Science Foundation of China No.51827901 and U2013603
文摘In situ pressure-preserved coring(IPP-Coring)technology is considered one of the most efficient methods for assessing resources.However,seal failure caused by the rotation of pressure controllers greatly affects the success of pressure coring.In this paper,a novel spherical-cylindrical shell pressure controller was proposed.The finite element analysis model was used to analyze the stress distribution and deformation characteristics of the pressure controller at different rotation angles.The seal failure mechanism caused by the rotation of the pressure controller was discussed.The stress deviation rate was defined to quantitatively characterize the stress concentration.Based on the test equipment designed in this laboratory,the ultimate bearing strength of the pressure controller was tested.The results show that the rotation of the valve cover causes an increase in the deformation on its lower side.Furthermore,the specific sealing pressure in the weak zone is greatly reduced by a statistically significant amount,resulting in seal failure.When the valve cover rotates 5°around the major axis,the stress deviation rate is-92.6%.To prevent rotating failure of the pressure controller,it is necessary to control the rotation angle of the valve cover within 1°around the major axis.The results of this research can help engineers reduce failure-related accidents,provide countermeasures for pressure coring,and contribute to the exploration and evaluation of deep oil and gas resources.
基金partially supported by the National Science Foundation of China(11272791,61364003,and 61203006)the Innovation Program of Shanghai Municipal Education Commission(10ZZ61 and 14ZZ151)the Science and Technology Foundation of Guizhou Province(20122316)
文摘In this letter, a distributed protocol for sampled-data synchronization of coupled harmonic oscillators with controller failure and communication delays is proposed, and a brief procedure of convergence analysis for such algorithm over undirected connected graphs is provided. Furthermore, a simple yet generic criterion is also presented to guarantee synchronized oscillatory motions in coupled harmonic oscillators. Subsequently, the simulation results are worked out to demonstrate the efficiency and feasibility of the theoretical results.
文摘针对软件定义网络(software defined network,SDN)中控制器发生故障问题,提出了一种基于多种群粒子群算法的SDN控制器故障恢复策略。从其他正常工作的子控制器集合中挑选出能够容纳失控交换机负载的备份控制器集,将精英种群与子种群组成多种群粒子群,采用预选和交互机制演化出备份控制器的最优位置,以保证交换机与控制器之间的传播时延最小,完成失控交换机的迁移。实验结果表明,相比于现有的控制器故障恢复算法,该算法在恢复时间、控制器负载利用方面均有所提升。
