ARP-based Distributed Denial of Service (DDoS) attacks due to ARP-storms can happen in local area networks where many computer systems are infected by worms such as Code Red or by DDoS agents. In ARP attack, the DDoS ...ARP-based Distributed Denial of Service (DDoS) attacks due to ARP-storms can happen in local area networks where many computer systems are infected by worms such as Code Red or by DDoS agents. In ARP attack, the DDoS agents constantly send a barrage of ARP requests to the gateway, or to a victim computer within the same sub-network, and tie up the resource of attacked gateway or host. In this paper, we set to measure the impact of ARP-attack on resource exhaustion of computers in a local area network. Based on attack experiments, we measure the exhaustion of processing and memory resources of a victim computer and also other computers, which are located on the same network as the victim computer. Interestingly enough, it is observed that an ARP-attack not only exhausts resource of the victim computer but also significantly exhausts processing resource of other non-victim computers, which happen to be located on the same local area network as the victim computer.展开更多
以视频传感器和图像传感器为代表的有向传感器,在保持连通性的前提下,网络覆盖面积很难最大化,低速率拒绝服务攻击在小面积内会造成带宽混乱拥堵,造成网络带宽分配不佳、分配错误率较高。为此,提出一种低速率拒绝服务攻击下有向传感器...以视频传感器和图像传感器为代表的有向传感器,在保持连通性的前提下,网络覆盖面积很难最大化,低速率拒绝服务攻击在小面积内会造成带宽混乱拥堵,造成网络带宽分配不佳、分配错误率较高。为此,提出一种低速率拒绝服务攻击下有向传感器网络带宽分配方法。建立低速率拒绝服务攻击(Denial of Service attack,DoS)有向传感器网络模型。将攻击频率及攻击时间作为约束条件,采用设计的资源调度器控制有向传感器网络参数,使其满足资源动态调度性能需求。利用动态带宽分配算法设定三种采样周期,并通过调整采样周期实现带宽分配。仿真结果表明,所提方法的平均时延低于23 ms,带宽利用率为94%,节点平均队列长度低于1.9。验证了该方法具有可靠性更高的带宽分配结果。展开更多
This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle （UCAV） performing autonomous air-to-surface （A/S） attack. It combines the benefits...This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle （UCAV） performing autonomous air-to-surface （A/S） attack. It combines the benefits of inverse dynamics optimization method and receding horizon optimal control technique. Firstly, the ground attack trajectory planning problem is mathematically formulated as a receding horizon optimal control problem （RHC-OCP）. In particular, an approximate elliptic launch acceptable region （LAR） model is proposed to model the critical weapon delivery constraints. Secondly, a planning algorithm based on inverse dynamics optimization, which has high computational efficiency and good convergence properties, is developed to solve the RHCOCP in real-time. Thirdly, in order to improve robustness and adaptivity in a dynamic and uncer- tain environment, a two-degree-of-freedom （2-DOF） receding horizon control architecture is introduced and a regular real-time update strategy is proposed as well, and the real-time feedback can be achieved and the not-converged situations can be handled. Finally, numerical simulations demon- strate the efficiency of this framework, and the results also show that the presented technique is well suited for real-time implementation in dynamic and uncertain environment.展开更多
A controlled bidirectional quantum secret direct communication scheme is proposed by using a Greenberger- Horne-Zeilinger （GHZ） state. In the scheme, two users can exchange their secret messages simultaneously with ...A controlled bidirectional quantum secret direct communication scheme is proposed by using a Greenberger- Horne-Zeilinger （GHZ） state. In the scheme, two users can exchange their secret messages simultaneously with a set of devices under the control of a third party. The security of the scheme is analysed and confirmed.展开更多
Experimental investigation of large amplitude yaw-roll coupled oscillations was conducted in a low-speed wind tunnel using an aircraft configuration model. A special test rig was designed and constructed to provide di...Experimental investigation of large amplitude yaw-roll coupled oscillations was conducted in a low-speed wind tunnel using an aircraft configuration model. A special test rig was designed and constructed to provide different coupled motions from low to high angles of attack.A parameter ‘‘coupling ratio" was introduced to indicate the extent of yaw-roll coupling. At each pitch angle, seven coupling ratios were designed to study the yaw-roll coupling effects on the lateraldirectional aerodynamic characteristics systematically. At high angles of attack, the damping characteristics of yawing and rolling moments drastically varied with coupling ratios. In the coupled motions with the rotation taking place about the wind axis, the lateral-directional aerodynamic moments exhibited unsteady characteristics and were different from the ‘‘quasi-steady" results of the rotary balance tests. The calculated results of the traditional aerodynamic derivative method were also compared with the experimental data. At low and very high angles of attack, the aerodynamic derivative method was applicative. However, within a wide range of angles of attack, the calculated results of aerodynamic derivative method were inconsistent with the experimental data, due to the drastic changes of damping characteristics of lateral-directional aerodynamic moments with yaw-roll coupling ratios.展开更多
This work aims at optimizing densification parameters as well as resistance to hydration and slag attack of MgO-Dolomite refractory grains, processed from Egyptian dolomitc-magnesite raw material up to firing for 1-4 ...This work aims at optimizing densification parameters as well as resistance to hydration and slag attack of MgO-Dolomite refractory grains, processed from Egyptian dolomitc-magnesite raw material up to firing for 1-4 h at 1400-1600 ℃, in relation to their phase composition and microfabric. Minor amount of natural ilmenite mineral (0-2 wt%), separated from Egyptian black sands was used in doping the dolomitc-magnesite.展开更多
To counter BTT guidance mode, new relative motion equations of the targetaircraft and the attack aircraft are proposed. The inverse system theory of the nonlinearcontrol is used, and the direct BTT-180 guidance comman...To counter BTT guidance mode, new relative motion equations of the targetaircraft and the attack aircraft are proposed. The inverse system theory of the nonlinearcontrol is used, and the direct BTT-180 guidance command is solved, which can operatethe attack aircraft to automatically complete the flight mission of the preceding stage ofthe terminal weapon delivery, and thus the automatic attack is extended from the stage ofthe terminal weapon delivery to the preceding stage of the terminal weapon delivery.展开更多
Software defined networking(SDN)has attracted significant attention from both academia and industry by its ability to reconfigure network devices with logically centralized applications.However,some critical security ...Software defined networking(SDN)has attracted significant attention from both academia and industry by its ability to reconfigure network devices with logically centralized applications.However,some critical security issues have also been introduced along with the benefits,which put an obstruction to the deployment of SDN.One root cause of these issues lies in the limited resources and capability of devices involved in the SDN architecture,especially the hardware switches lied in the data plane.In this paper,we analyze the vulnerability of SDN and present two kinds of SDN-targeted attacks:1)data-to-control plane saturation attack which exhausts resources of all SDN components,including control plane,data plane,and the in-between downlink channel and 2)control plane reflection attack which only attacks the data plane and gets conducted in a more efficient and hidden way.Finally,we propose the corresponding defense frameworks to mitigate such attacks.展开更多
文摘ARP-based Distributed Denial of Service (DDoS) attacks due to ARP-storms can happen in local area networks where many computer systems are infected by worms such as Code Red or by DDoS agents. In ARP attack, the DDoS agents constantly send a barrage of ARP requests to the gateway, or to a victim computer within the same sub-network, and tie up the resource of attacked gateway or host. In this paper, we set to measure the impact of ARP-attack on resource exhaustion of computers in a local area network. Based on attack experiments, we measure the exhaustion of processing and memory resources of a victim computer and also other computers, which are located on the same network as the victim computer. Interestingly enough, it is observed that an ARP-attack not only exhausts resource of the victim computer but also significantly exhausts processing resource of other non-victim computers, which happen to be located on the same local area network as the victim computer.
文摘以视频传感器和图像传感器为代表的有向传感器,在保持连通性的前提下,网络覆盖面积很难最大化,低速率拒绝服务攻击在小面积内会造成带宽混乱拥堵,造成网络带宽分配不佳、分配错误率较高。为此,提出一种低速率拒绝服务攻击下有向传感器网络带宽分配方法。建立低速率拒绝服务攻击(Denial of Service attack,DoS)有向传感器网络模型。将攻击频率及攻击时间作为约束条件,采用设计的资源调度器控制有向传感器网络参数,使其满足资源动态调度性能需求。利用动态带宽分配算法设定三种采样周期,并通过调整采样周期实现带宽分配。仿真结果表明,所提方法的平均时延低于23 ms,带宽利用率为94%,节点平均队列长度低于1.9。验证了该方法具有可靠性更高的带宽分配结果。
基金supported by the National Defense Foundation of China(No.403060103)
文摘This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle （UCAV） performing autonomous air-to-surface （A/S） attack. It combines the benefits of inverse dynamics optimization method and receding horizon optimal control technique. Firstly, the ground attack trajectory planning problem is mathematically formulated as a receding horizon optimal control problem （RHC-OCP）. In particular, an approximate elliptic launch acceptable region （LAR） model is proposed to model the critical weapon delivery constraints. Secondly, a planning algorithm based on inverse dynamics optimization, which has high computational efficiency and good convergence properties, is developed to solve the RHCOCP in real-time. Thirdly, in order to improve robustness and adaptivity in a dynamic and uncer- tain environment, a two-degree-of-freedom （2-DOF） receding horizon control architecture is introduced and a regular real-time update strategy is proposed as well, and the real-time feedback can be achieved and the not-converged situations can be handled. Finally, numerical simulations demon- strate the efficiency of this framework, and the results also show that the presented technique is well suited for real-time implementation in dynamic and uncertain environment.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10534030 and 10304022.
文摘A controlled bidirectional quantum secret direct communication scheme is proposed by using a Greenberger- Horne-Zeilinger （GHZ） state. In the scheme, two users can exchange their secret messages simultaneously with a set of devices under the control of a third party. The security of the scheme is analysed and confirmed.
基金supported by the National Natural Science Foundation of China (No. 11072111)
文摘Experimental investigation of large amplitude yaw-roll coupled oscillations was conducted in a low-speed wind tunnel using an aircraft configuration model. A special test rig was designed and constructed to provide different coupled motions from low to high angles of attack.A parameter ‘‘coupling ratio" was introduced to indicate the extent of yaw-roll coupling. At each pitch angle, seven coupling ratios were designed to study the yaw-roll coupling effects on the lateraldirectional aerodynamic characteristics systematically. At high angles of attack, the damping characteristics of yawing and rolling moments drastically varied with coupling ratios. In the coupled motions with the rotation taking place about the wind axis, the lateral-directional aerodynamic moments exhibited unsteady characteristics and were different from the ‘‘quasi-steady" results of the rotary balance tests. The calculated results of the traditional aerodynamic derivative method were also compared with the experimental data. At low and very high angles of attack, the aerodynamic derivative method was applicative. However, within a wide range of angles of attack, the calculated results of aerodynamic derivative method were inconsistent with the experimental data, due to the drastic changes of damping characteristics of lateral-directional aerodynamic moments with yaw-roll coupling ratios.
文摘This work aims at optimizing densification parameters as well as resistance to hydration and slag attack of MgO-Dolomite refractory grains, processed from Egyptian dolomitc-magnesite raw material up to firing for 1-4 h at 1400-1600 ℃, in relation to their phase composition and microfabric. Minor amount of natural ilmenite mineral (0-2 wt%), separated from Egyptian black sands was used in doping the dolomitc-magnesite.
文摘To counter BTT guidance mode, new relative motion equations of the targetaircraft and the attack aircraft are proposed. The inverse system theory of the nonlinearcontrol is used, and the direct BTT-180 guidance command is solved, which can operatethe attack aircraft to automatically complete the flight mission of the preceding stage ofthe terminal weapon delivery, and thus the automatic attack is extended from the stage ofthe terminal weapon delivery to the preceding stage of the terminal weapon delivery.
基金supported in part by the National Key R&D Program of China under Grant No.2017YFB0801701the National Science Foundation of China under Grant No.61472213CERNET Innovation Project(NGII20160123)
文摘Software defined networking(SDN)has attracted significant attention from both academia and industry by its ability to reconfigure network devices with logically centralized applications.However,some critical security issues have also been introduced along with the benefits,which put an obstruction to the deployment of SDN.One root cause of these issues lies in the limited resources and capability of devices involved in the SDN architecture,especially the hardware switches lied in the data plane.In this paper,we analyze the vulnerability of SDN and present two kinds of SDN-targeted attacks:1)data-to-control plane saturation attack which exhausts resources of all SDN components,including control plane,data plane,and the in-between downlink channel and 2)control plane reflection attack which only attacks the data plane and gets conducted in a more efficient and hidden way.Finally,we propose the corresponding defense frameworks to mitigate such attacks.
