民用飞机后舱包括信息系统(Information System,IS)、客舱核心系统(Cabin Core System,CCS)、机载娱乐(In-Flight Entertainment,IFE)系统、外部通信系统(External Communication System,ECS)等,各系统飞行安全域等级不同且网络交联关...民用飞机后舱包括信息系统(Information System,IS)、客舱核心系统(Cabin Core System,CCS)、机载娱乐(In-Flight Entertainment,IFE)系统、外部通信系统(External Communication System,ECS)等,各系统飞行安全域等级不同且网络交联关系复杂,这对传输服务质量(Quality of Service,QoS)提出极高要求,传统的QoS算法难以达到最佳效果。针对上述问题,将公平队列调度(Fair Weight Queue,FWQ)算法和随机早期检测(Random Early Detection,RED)算法相结合,整合到QoS处理系统上,并利用优先级双因素(Two-Factor,TF)机制对数据流进行精细化描述,提出一种民用飞机后舱一体化网络改进型QoS算法,命名为双因素加权公平队列随机早期检测(Two Factor-Fair Weighted Queue-Random Early Detection,TF-FWQ-RED)算法,使用OPNET网络仿真工具对该算法进行仿真验证。仿真运行结果显示,通过该算法可有效降低后舱高优先级业务流在网络拥塞场景下受延迟或丢包率的影响,同时保证了网络的高效运行,表明了TF-FWQ-RED算法的正确性以及对民机后舱混合复杂网络环境下现实需求的适应性。展开更多
This study investigates the effects of multiphase internal flows that consider hydrate phase transitions on the parametric stability of marine risers.A numerical model of the multiphase internal flow that considers a ...This study investigates the effects of multiphase internal flows that consider hydrate phase transitions on the parametric stability of marine risers.A numerical model of the multiphase internal flow that considers a hydrate phase transition is established.The model first solves the flow parameters and subsequently obtains the natural frequencies of risers with different gas intake ratios.The stability charts of marine risers with different gas intake ratios are plotted by applying Floquet theory,and the effects of the gas intake ratio on the instability and vibration response of the risers are identified.The natural frequency increases with an increase in the gas intake ratio;thus,instability zones move to higher frequency ranges in the stability charts.As the increasing gas intake ratio reduces the damping effect of the Coriolis force,the critical amplitude of the heave in the unstable region decreases,especially when hydrodynamic damping is not considered.As a result,higher-order unstable regions are excited.When in an unstable region,the vibration response curve of a riser with a high gas intake ratio excited by parametric resonance diverges quickly due to parametric resonance.展开更多
文摘民用飞机后舱包括信息系统(Information System,IS)、客舱核心系统(Cabin Core System,CCS)、机载娱乐(In-Flight Entertainment,IFE)系统、外部通信系统(External Communication System,ECS)等,各系统飞行安全域等级不同且网络交联关系复杂,这对传输服务质量(Quality of Service,QoS)提出极高要求,传统的QoS算法难以达到最佳效果。针对上述问题,将公平队列调度(Fair Weight Queue,FWQ)算法和随机早期检测(Random Early Detection,RED)算法相结合,整合到QoS处理系统上,并利用优先级双因素(Two-Factor,TF)机制对数据流进行精细化描述,提出一种民用飞机后舱一体化网络改进型QoS算法,命名为双因素加权公平队列随机早期检测(Two Factor-Fair Weighted Queue-Random Early Detection,TF-FWQ-RED)算法,使用OPNET网络仿真工具对该算法进行仿真验证。仿真运行结果显示,通过该算法可有效降低后舱高优先级业务流在网络拥塞场景下受延迟或丢包率的影响,同时保证了网络的高效运行,表明了TF-FWQ-RED算法的正确性以及对民机后舱混合复杂网络环境下现实需求的适应性。
基金funded by the National Natural Sci-ence Foundation of China(No.U2006226)the National Key Research and Development Program of China(No.2016YFC0303800)the National Natural Science Foundation of China(No.51579245)。
文摘This study investigates the effects of multiphase internal flows that consider hydrate phase transitions on the parametric stability of marine risers.A numerical model of the multiphase internal flow that considers a hydrate phase transition is established.The model first solves the flow parameters and subsequently obtains the natural frequencies of risers with different gas intake ratios.The stability charts of marine risers with different gas intake ratios are plotted by applying Floquet theory,and the effects of the gas intake ratio on the instability and vibration response of the risers are identified.The natural frequency increases with an increase in the gas intake ratio;thus,instability zones move to higher frequency ranges in the stability charts.As the increasing gas intake ratio reduces the damping effect of the Coriolis force,the critical amplitude of the heave in the unstable region decreases,especially when hydrodynamic damping is not considered.As a result,higher-order unstable regions are excited.When in an unstable region,the vibration response curve of a riser with a high gas intake ratio excited by parametric resonance diverges quickly due to parametric resonance.
