软件定义网络(Soft Defined Network,SDN)交换机作为数据转发与策略执行的设备,恶意攻击者通过侵蚀SDN交换机对网络进行隐秘而致命的攻击,严重影响用户的端到端通信质量。首先提出了一种边缘交换机被攻击者劫持后的数据窃取攻击过程,可...软件定义网络(Soft Defined Network,SDN)交换机作为数据转发与策略执行的设备,恶意攻击者通过侵蚀SDN交换机对网络进行隐秘而致命的攻击,严重影响用户的端到端通信质量。首先提出了一种边缘交换机被攻击者劫持后的数据窃取攻击过程,可以逃避网络范围内的异常检测,并证明了这种攻击的隐蔽性。为了抵御此种攻击,提出了一种流信息一致性检测方法,将主机信息纳入一致性检测中,并基于Ryu控制器在mininet平台上进行实验。实验结果表明,防御方法在抵御边缘交换机攻击的同时不会带来过多的负载增加。展开更多
针对移动机器人噪声模型不确定性导致定位算法鲁棒性弱、精度低的问题,提出一种基于奇异值分解(Singular Value Decomposition,SVD)的自适应无迹H_(∞)滤波定位算法。该算法利用无迹H_(∞)滤波融合多传感器数据估计移动机器人位姿,并通...针对移动机器人噪声模型不确定性导致定位算法鲁棒性弱、精度低的问题,提出一种基于奇异值分解(Singular Value Decomposition,SVD)的自适应无迹H_(∞)滤波定位算法。该算法利用无迹H_(∞)滤波融合多传感器数据估计移动机器人位姿,并通过自适应调节滤波器参数γ,提高了移动机器人的定位精度。同时为了提高算法的鲁棒性,采用SVD分解代替常规Cholesky分解,避免了误差协方差矩阵在数值迭代过程中出现负定的情况。实验结果表明:相较于扩展H_(∞)滤波和粒子滤波算法,基于SVD分解的自适应无迹H_(∞)滤波定位算法具有精度高、鲁棒性强的优势。展开更多
Biofouling has been a persistent problem in marine riser system, resulting in energy waste and equipment damage. Inthis study, a kind of water wave-driven contact-mode flexible triboelectric nanogeneration has been pr...Biofouling has been a persistent problem in marine riser system, resulting in energy waste and equipment damage. Inthis study, a kind of water wave-driven contact-mode flexible triboelectric nanogeneration has been prepared byusing graphene-doped PDMS as dielectric friction material. When the graphene content is 2%, the average outputvoltage can reach 46 V under the contact frequency 10 Hz. The flexible triboelectric nanogeneration encapsulationmodule is impinged by water waves to generate alternating microelectric field on the riser surface and destroy theadhesion conditions of microorganisms during the biofilm stage. In the biofouling experiments at different stages, thebiofouling area of the platymonas subcordiformis has been reduced by 53%, 62% and 61%. It provides a new ideafor effective treatment of biofouling of mussels, oysters and barnacles attached to risers.展开更多
Applying pressure has been evidenced as an effective method to control the properties of semiconductors,owing to its capability to modify the band configuration around Fermi energy.Correspondingly,structural evolution...Applying pressure has been evidenced as an effective method to control the properties of semiconductors,owing to its capability to modify the band configuration around Fermi energy.Correspondingly,structural evolutions under external pres-sures are required to analyze the mechanisms.Herein high-pressure structure of a magnetic doped semiconductor Ba(Zn_(0.95)Mn_(0.05))_(2)As_(2)is studied with combination of in-situ synchrotron X-ray diffractions and diamond anvil cells.The materials become ferromagnetic with Curie temperature of 105 K after further 20%K doping.The title material undergoes an isostruc-tural phase transition at around 19 GPa.Below the transition pressure,it is remarkable to find lengthening of Zn/Mn-As bond within Zn/MnAs layers,since chemical bonds are generally shortened with applying pressures.Accompanied with the bond stretch,interlayer As-As distances become shorter and the As-As dimers form after the phase transition.With further compres-sion,Zn/Mn-As bond becomes shortened due to the recovery of isotropic compression on the Zn/MnAs layers.展开更多
随着大量分布式能源终端接入,智慧园区中爆炸式增长的业务对队列积压、误码率、吞吐量等服务质量(quality of service,QoS)需求差异性大,现有的路由优化与差异化业务需求适配性差、时间同步与路由优化存在耦合性、链路与网络拥塞信息的...随着大量分布式能源终端接入,智慧园区中爆炸式增长的业务对队列积压、误码率、吞吐量等服务质量(quality of service,QoS)需求差异性大,现有的路由优化与差异化业务需求适配性差、时间同步与路由优化存在耦合性、链路与网络拥塞信息的不确定性等挑战,影响园区网络路由性能。针对上述挑战,提出了一种联合背压和Q学习的时间同步感知多态路由协议(backprEssure and Q-Learning based timE synChronizaTion-aware polymoRphic routIng protoCol,ELECTRIC)算法。首先,建立时间同步感知多态路由协议架构,实现园区终端的集中管理和数据传输优化;其次,根据背压算法,将队列积压最小化问题转化为队列积压差最大化问题,避免网络拥塞;然后,利用时间偏差阈值的概念对时间同步进行感知,使延迟唤醒的休眠态终端变为活跃态,并基于本地和历史信息进一步学习最优路由选择策略;最后,通过仿真结果验证,相较于基于Q学习的路由选择(Q-learning based route selection,QLRS)算法和基于队列积压的背压路由选择(queue backlog based backpressure route selection,QBBRS)算法,所提算法可分别提高平均吞吐量17.39%和56.52%,降低平均队列积压33.86%和44.07%,降低误码率31.58%和58.06%,保障智慧园区不同业务差异化的QoS需求。展开更多
文摘软件定义网络(Soft Defined Network,SDN)交换机作为数据转发与策略执行的设备,恶意攻击者通过侵蚀SDN交换机对网络进行隐秘而致命的攻击,严重影响用户的端到端通信质量。首先提出了一种边缘交换机被攻击者劫持后的数据窃取攻击过程,可以逃避网络范围内的异常检测,并证明了这种攻击的隐蔽性。为了抵御此种攻击,提出了一种流信息一致性检测方法,将主机信息纳入一致性检测中,并基于Ryu控制器在mininet平台上进行实验。实验结果表明,防御方法在抵御边缘交换机攻击的同时不会带来过多的负载增加。
文摘针对移动机器人噪声模型不确定性导致定位算法鲁棒性弱、精度低的问题,提出一种基于奇异值分解(Singular Value Decomposition,SVD)的自适应无迹H_(∞)滤波定位算法。该算法利用无迹H_(∞)滤波融合多传感器数据估计移动机器人位姿,并通过自适应调节滤波器参数γ,提高了移动机器人的定位精度。同时为了提高算法的鲁棒性,采用SVD分解代替常规Cholesky分解,避免了误差协方差矩阵在数值迭代过程中出现负定的情况。实验结果表明:相较于扩展H_(∞)滤波和粒子滤波算法,基于SVD分解的自适应无迹H_(∞)滤波定位算法具有精度高、鲁棒性强的优势。
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB3401400)。
文摘Biofouling has been a persistent problem in marine riser system, resulting in energy waste and equipment damage. Inthis study, a kind of water wave-driven contact-mode flexible triboelectric nanogeneration has been prepared byusing graphene-doped PDMS as dielectric friction material. When the graphene content is 2%, the average outputvoltage can reach 46 V under the contact frequency 10 Hz. The flexible triboelectric nanogeneration encapsulationmodule is impinged by water waves to generate alternating microelectric field on the riser surface and destroy theadhesion conditions of microorganisms during the biofilm stage. In the biofouling experiments at different stages, thebiofouling area of the platymonas subcordiformis has been reduced by 53%, 62% and 61%. It provides a new ideafor effective treatment of biofouling of mussels, oysters and barnacles attached to risers.
基金supported by Beijing Natural Science Foundation (No. 2212049)NSF of China (No. 11974407)+1 种基金CAS Project for Young Scientists in Basic Research (No. YSBR-030)the Youth Innovation Promotion Association of CAS (No. 2020007)
文摘Applying pressure has been evidenced as an effective method to control the properties of semiconductors,owing to its capability to modify the band configuration around Fermi energy.Correspondingly,structural evolutions under external pres-sures are required to analyze the mechanisms.Herein high-pressure structure of a magnetic doped semiconductor Ba(Zn_(0.95)Mn_(0.05))_(2)As_(2)is studied with combination of in-situ synchrotron X-ray diffractions and diamond anvil cells.The materials become ferromagnetic with Curie temperature of 105 K after further 20%K doping.The title material undergoes an isostruc-tural phase transition at around 19 GPa.Below the transition pressure,it is remarkable to find lengthening of Zn/Mn-As bond within Zn/MnAs layers,since chemical bonds are generally shortened with applying pressures.Accompanied with the bond stretch,interlayer As-As distances become shorter and the As-As dimers form after the phase transition.With further compres-sion,Zn/Mn-As bond becomes shortened due to the recovery of isotropic compression on the Zn/MnAs layers.
文摘随着大量分布式能源终端接入,智慧园区中爆炸式增长的业务对队列积压、误码率、吞吐量等服务质量(quality of service,QoS)需求差异性大,现有的路由优化与差异化业务需求适配性差、时间同步与路由优化存在耦合性、链路与网络拥塞信息的不确定性等挑战,影响园区网络路由性能。针对上述挑战,提出了一种联合背压和Q学习的时间同步感知多态路由协议(backprEssure and Q-Learning based timE synChronizaTion-aware polymoRphic routIng protoCol,ELECTRIC)算法。首先,建立时间同步感知多态路由协议架构,实现园区终端的集中管理和数据传输优化;其次,根据背压算法,将队列积压最小化问题转化为队列积压差最大化问题,避免网络拥塞;然后,利用时间偏差阈值的概念对时间同步进行感知,使延迟唤醒的休眠态终端变为活跃态,并基于本地和历史信息进一步学习最优路由选择策略;最后,通过仿真结果验证,相较于基于Q学习的路由选择(Q-learning based route selection,QLRS)算法和基于队列积压的背压路由选择(queue backlog based backpressure route selection,QBBRS)算法,所提算法可分别提高平均吞吐量17.39%和56.52%,降低平均队列积压33.86%和44.07%,降低误码率31.58%和58.06%,保障智慧园区不同业务差异化的QoS需求。
