With the explosive increasing number of connecting devices such as smart phones, vehicles,drones, and satellites in the wireless networks, how to manage and control such a huge number of networking nodes has become a ...With the explosive increasing number of connecting devices such as smart phones, vehicles,drones, and satellites in the wireless networks, how to manage and control such a huge number of networking nodes has become a great challenge. In this paper, we combine the advantages of centralized networks and distributed networks approaches for vehicular networks with the aid of Unmanned Aerial Vehicle(UAV), and propose a Center-controlled Multihop Wireless(CMW) networking scheme consisting of data transmission plane performed by vehicles and the network control plane implemented by the UAV.Besides, we jointly explore the advantages of Medium Access Control(MAC) protocols in the link layer and routing schemes in the network layer to facilitate the multi-hop data transmission for the ground vehicles.Particularly, the network control plane in the UAV can manage the whole network effectively via fully exploiting the acquired network topology information and traffic requests from each vehicle, and implements various kinds of control based on different traffic demands, which can enhance the networking flexibility and scalability significantly in vehicular networks.Simulation results validate the advantages of the proposed scheme compared with existing methods.展开更多
以一起V2500-A5发动机排气温度(Exhaust Gas Temperature,EGT)的真实超限故障为切入点,阐述了影响发动机EGT的因素,以及发动机各主要部件对EGT的影响程度。通过发动机监控系统和原理分析锁定故障源,以期为同类故障的快速处置和排除提供...以一起V2500-A5发动机排气温度(Exhaust Gas Temperature,EGT)的真实超限故障为切入点,阐述了影响发动机EGT的因素,以及发动机各主要部件对EGT的影响程度。通过发动机监控系统和原理分析锁定故障源,以期为同类故障的快速处置和排除提供参考。展开更多
针对临近空间高超声速飞行器目标探测与识别研究的需求,开展了高超声速飞行器非均匀等离子体电磁散射特性模拟测量研究.利用弹道靶设备发射高超声速类HTV2模型形成模拟的超高速复杂外形目标,弹道靶高精度阴影成像系统和雷达测量系统分...针对临近空间高超声速飞行器目标探测与识别研究的需求,开展了高超声速飞行器非均匀等离子体电磁散射特性模拟测量研究.利用弹道靶设备发射高超声速类HTV2模型形成模拟的超高速复杂外形目标,弹道靶高精度阴影成像系统和雷达测量系统分别测量高超声速类HTV2模型姿态、全目标C波段/X波段电磁散射特性,获得了不同实验条件下模型全目标雷达散射截面积(RCS)等实验数据.研究结果表明:在不同实验状态下,包覆等离子体鞘套的高超声速类HTV2模型同一测量波段的RCS差别超过1个数量级,模型姿态角对包覆等离子体鞘套的高超声速类HTV2模型RCS影响较大,最大相差1个多数量级;在给定的实验条件下,模型尾迹C波段RCS远小于包覆等离子体鞘套的模型RCS,模型尾迹X波段RCS显著增强;高超声速类HTV2模型全目标C波段电磁散射能量主要分布在模型及其绕流区域, X波段电磁散射能量主要分布在模型及其绕流区域和等离子体尾迹区域.根据弹道靶实验条件,开展了包覆等离子体鞘套的高超声速类HTV2模型电磁散射特性数值仿真,仿真结果与实验结果之间的最大误差小于4 d B,验证了本文提出的非均匀等离子体包覆目标电磁散射特性建模方法的有效性.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 62071283,Grant 61771296,Grant 61872228 and Grant 62271513in part by the Natural Science Basic Research Plan in Shaanxi Province of China under Grant 2018JQ6048 and Grant 2018JZ6006+3 种基金in part by Shaanxi Key Industrial Innovation Chain Project in Industrial Domain under Grant 2020ZDLGY15-09in part by Guang Dong Basic and Applied Basic Research Foundation under Grant 2021A1515012631in part by China Postdoctoral Science Foundation under Grant 2016M600761in part by the Fundamental Research Funds for the Central Universities under Grant GK202003075 and Grant GK202103016。
文摘With the explosive increasing number of connecting devices such as smart phones, vehicles,drones, and satellites in the wireless networks, how to manage and control such a huge number of networking nodes has become a great challenge. In this paper, we combine the advantages of centralized networks and distributed networks approaches for vehicular networks with the aid of Unmanned Aerial Vehicle(UAV), and propose a Center-controlled Multihop Wireless(CMW) networking scheme consisting of data transmission plane performed by vehicles and the network control plane implemented by the UAV.Besides, we jointly explore the advantages of Medium Access Control(MAC) protocols in the link layer and routing schemes in the network layer to facilitate the multi-hop data transmission for the ground vehicles.Particularly, the network control plane in the UAV can manage the whole network effectively via fully exploiting the acquired network topology information and traffic requests from each vehicle, and implements various kinds of control based on different traffic demands, which can enhance the networking flexibility and scalability significantly in vehicular networks.Simulation results validate the advantages of the proposed scheme compared with existing methods.
文摘针对临近空间高超声速飞行器目标探测与识别研究的需求,开展了高超声速飞行器非均匀等离子体电磁散射特性模拟测量研究.利用弹道靶设备发射高超声速类HTV2模型形成模拟的超高速复杂外形目标,弹道靶高精度阴影成像系统和雷达测量系统分别测量高超声速类HTV2模型姿态、全目标C波段/X波段电磁散射特性,获得了不同实验条件下模型全目标雷达散射截面积(RCS)等实验数据.研究结果表明:在不同实验状态下,包覆等离子体鞘套的高超声速类HTV2模型同一测量波段的RCS差别超过1个数量级,模型姿态角对包覆等离子体鞘套的高超声速类HTV2模型RCS影响较大,最大相差1个多数量级;在给定的实验条件下,模型尾迹C波段RCS远小于包覆等离子体鞘套的模型RCS,模型尾迹X波段RCS显著增强;高超声速类HTV2模型全目标C波段电磁散射能量主要分布在模型及其绕流区域, X波段电磁散射能量主要分布在模型及其绕流区域和等离子体尾迹区域.根据弹道靶实验条件,开展了包覆等离子体鞘套的高超声速类HTV2模型电磁散射特性数值仿真,仿真结果与实验结果之间的最大误差小于4 d B,验证了本文提出的非均匀等离子体包覆目标电磁散射特性建模方法的有效性.
