The outbreak of a novel coronavirus(SARS-CoV-2)has resulted in a worldwide pandemic infecting over 5.9 million people[1].This positive-strand RNA virus can cause severe respiratory distress syndrome in humans(COVID-19...The outbreak of a novel coronavirus(SARS-CoV-2)has resulted in a worldwide pandemic infecting over 5.9 million people[1].This positive-strand RNA virus can cause severe respiratory distress syndrome in humans(COVID-19),with over 364,000 deaths between December 2019 and May 30,2020[1,2].To combat this pandemic,the World Health Organization(WHO)is coordinating global efforts on surveillance,epidemiology,mathematical model-ing,diagnostics,treatment and control,and has issued interim guidance to countries.Nevertheless,this is a difficult situation and the number of cases is rapidly increasing globally.The tempo-ral evolution and the spatial spread of this virus have also raised serious concerns about the future trajectory of this outbreak.展开更多
由于数据流的动态性和流量负载转移,软件定义网络(software defined networking,简称SDN)需要频繁更新数据平面以优化网络性能.大多数已有路由更新策略首先根据网络当前流量状态确定目标路由配置,然后更新数据流的路由.然而,由于交换机...由于数据流的动态性和流量负载转移,软件定义网络(software defined networking,简称SDN)需要频繁更新数据平面以优化网络性能.大多数已有路由更新策略首先根据网络当前流量状态确定目标路由配置,然后更新数据流的路由.然而,由于交换机基于TCAM(ternary content addressable memory)进行流表更新的速度较慢,导致路由更新的延迟通常较大.当网络规模大或网络拓扑结构经常变化时,路由更新的延迟可能更大.研究发现,大多数数据流的持续时间很短且整个网络的流量强度在一段时间后会发生变化.如果路由更新延迟过长,更新后的路由配置可能不再有效.为此,研究了SDN的实时路由更新问题,提出了延迟满足的路由选择和调度更新策略(delay satisfied route selection and updating scheme,简称DSRSU).与大多数现有研究不同,DSRSU同时从控制平面路径选择和数据平面的更新调度两方面来联合优化,降低路由更新的延迟.路径选择阶段只选择部分数据流进行路由更新;更新调度阶段通过建立更新关系图挖掘数据流的更新先后顺序,进一步加快路由更新速度.仿真分析结果表明,与现有几种路由更新策略相比,DSRSU能够在大幅度降低路由更新延迟的同时,达到与现有策略相似的网络性能。展开更多
背景数字孪生(The Digital Twin)的设想最早于2001年由密歇根大学的麦克·格雷夫斯(Michael Grieves)教授提出。近期由于技术进步,这一设想逐步在一些行业中得以进一步探索。简而言之,数字孪生是物质产品或资产的虚拟复制品,且可得...背景数字孪生(The Digital Twin)的设想最早于2001年由密歇根大学的麦克·格雷夫斯(Michael Grieves)教授提出。近期由于技术进步,这一设想逐步在一些行业中得以进一步探索。简而言之,数字孪生是物质产品或资产的虚拟复制品,且可得以实时更新或周期性更新,使其与真实世界的对应物尽可能的一致1。展开更多
基金jointly supported by the National Natural Science Foundation of China (41521004)the Gansu Provincial Special Fund Project for Guiding Scientific and Technological Innovation and Development (2019ZX-06)。
文摘The outbreak of a novel coronavirus(SARS-CoV-2)has resulted in a worldwide pandemic infecting over 5.9 million people[1].This positive-strand RNA virus can cause severe respiratory distress syndrome in humans(COVID-19),with over 364,000 deaths between December 2019 and May 30,2020[1,2].To combat this pandemic,the World Health Organization(WHO)is coordinating global efforts on surveillance,epidemiology,mathematical model-ing,diagnostics,treatment and control,and has issued interim guidance to countries.Nevertheless,this is a difficult situation and the number of cases is rapidly increasing globally.The tempo-ral evolution and the spatial spread of this virus have also raised serious concerns about the future trajectory of this outbreak.
文摘背景数字孪生(The Digital Twin)的设想最早于2001年由密歇根大学的麦克·格雷夫斯(Michael Grieves)教授提出。近期由于技术进步,这一设想逐步在一些行业中得以进一步探索。简而言之,数字孪生是物质产品或资产的虚拟复制品,且可得以实时更新或周期性更新,使其与真实世界的对应物尽可能的一致1。
