提出了一种无监督的两阶段聚类算法TPC(Two-Phase Clustering Algorithm)用于识别DoS(denial of service)/DDoS(distributed denial of service)攻击流数据,算法第一阶段根据样本的距离相似性计算密度区域和稀疏区域,利用密度连接的概...提出了一种无监督的两阶段聚类算法TPC(Two-Phase Clustering Algorithm)用于识别DoS(denial of service)/DDoS(distributed denial of service)攻击流数据,算法第一阶段根据样本的距离相似性计算密度区域和稀疏区域,利用密度连接的概念对样本集进行初步聚合,第二阶段利用聚类内部的散布程度和样本平均距离来表示计算聚类之间的相似性,对性质相似的聚类进一步递归聚合.算法不仅够识别不规则形状的聚类,还能识别对不同密度的聚类,解决了密度聚类算法需要设置合适的全局参数的弊端.展开更多
无线网络由于其传输介质及通信规程的特殊性,除了要面对有线网络中存在的各种拒绝服务(denial of service,DoS)攻击之外,还面临着一些在无线环境下特有的DoS攻击。针对由伪造协议会话中使用的管理帧和EAP帧发起的DoS攻击,提出了一种基...无线网络由于其传输介质及通信规程的特殊性,除了要面对有线网络中存在的各种拒绝服务(denial of service,DoS)攻击之外,还面临着一些在无线环境下特有的DoS攻击。针对由伪造协议会话中使用的管理帧和EAP帧发起的DoS攻击,提出了一种基于规范的自适应检测方法(WSBA),为无线局域网所执行的安全协议建立在正常运行时的状态转移模型连同网络安全策略约束定义作为检测规范,作为检测此类DoS攻击的依据。给出了检测阈值的自适应调整算法,分析了算法参数设置对检测性能的影响。实验测试结果表明该方法是正确而有效的。展开更多
In this work,the Fukui functions of the two ~2P resonance states of Be,a ~2P resonance state of Mg~–,and a ~2D resonance state of Ca~– have been determined.The trajectories of these resonance states,in conjunction w...In this work,the Fukui functions of the two ~2P resonance states of Be,a ~2P resonance state of Mg~–,and a ~2D resonance state of Ca~– have been determined.The trajectories of these resonance states,in conjunction with the complex rotation of the Hamiltonian,were used to determine their wave functions.The electron densities,Fukui functions,and values of the hyper-radius<r^2>were computed from these wave functions.The Fukui functions have negative regions in the valence shell in addition to the inner shell regions,indicating screening effects of the outer temporary electron.Selected configuration interactions with up to quadruple excitations were used along the trajectories and for computing the final wave function.Based on this data,the densities,Fukui functions,and<r^2>were calculated.展开更多
The density functional theory and its extension to ensembles of excited states can be formalized as thermodynamics. However, these theories are not unique because one of their key quantities, the kinetic energy densit...The density functional theory and its extension to ensembles of excited states can be formalized as thermodynamics. However, these theories are not unique because one of their key quantities, the kinetic energy density,can be defined in several ways. Usually, the everywhere positive gradient form is applied; however, other forms are also acceptable, provided they integrate to the true kinetic energy. Recently, a kinetic energy density of the ground-state theory maximizing the information entropy has been proposed. Here, ensemble kinetic energy density, leading to extremum information entropy, is derived via constrained search. The corresponding ensemble temperature is found to be constant.展开更多
Traditional track dynamic geometric state(TDGS)simulation incurs substantial computational burdens,posing challenges for developing reliability assessment approach that accounts for TDGS.To overcome these,firstly,a si...Traditional track dynamic geometric state(TDGS)simulation incurs substantial computational burdens,posing challenges for developing reliability assessment approach that accounts for TDGS.To overcome these,firstly,a simulation-based TDGS model is established,and a surrogate-based model,grid search algorithm-particle swarm optimization-genetic algorithm-multi-output least squares support vector regression,is established.Among them,hyperparameter optimization algorithm’s effectiveness is confirmed through test functions.Subsequently,an adaptive surrogate-based probability density evolution method(PDEM)considering random track geometry irregularity(TGI)is developed.Finally,taking curved train-steel spring floating slab track-U beam as case study,the surrogate-based model trained on simulation datasets not only shows accuracy in both time and frequency domains,but also surpasses existing models.Additionally,the adaptive surrogate-based PDEM shows high accuracy and efficiency,outperforming Monte Carlo simulation and simulation-based PDEM.The reliability assessment shows that the TDGS part peak management indexes,left/right vertical dynamic irregularity,right alignment dynamic irregularity,and track twist,have reliability values of 0.9648,0.9918,0.9978,and 0.9901,respectively.The TDGS mean management index,i.e.,track quality index,has reliability value of 0.9950.These findings show that the proposed framework can accurately and efficiently assess the reliability of curved low-stiffness track-viaducts,providing a theoretical basis for the TGI maintenance.展开更多
文摘提出了一种无监督的两阶段聚类算法TPC(Two-Phase Clustering Algorithm)用于识别DoS(denial of service)/DDoS(distributed denial of service)攻击流数据,算法第一阶段根据样本的距离相似性计算密度区域和稀疏区域,利用密度连接的概念对样本集进行初步聚合,第二阶段利用聚类内部的散布程度和样本平均距离来表示计算聚类之间的相似性,对性质相似的聚类进一步递归聚合.算法不仅够识别不规则形状的聚类,还能识别对不同密度的聚类,解决了密度聚类算法需要设置合适的全局参数的弊端.
文摘无线网络由于其传输介质及通信规程的特殊性,除了要面对有线网络中存在的各种拒绝服务(denial of service,DoS)攻击之外,还面临着一些在无线环境下特有的DoS攻击。针对由伪造协议会话中使用的管理帧和EAP帧发起的DoS攻击,提出了一种基于规范的自适应检测方法(WSBA),为无线局域网所执行的安全协议建立在正常运行时的状态转移模型连同网络安全策略约束定义作为检测规范,作为检测此类DoS攻击的依据。给出了检测阈值的自适应调整算法,分析了算法参数设置对检测性能的影响。实验测试结果表明该方法是正确而有效的。
文摘In this work,the Fukui functions of the two ~2P resonance states of Be,a ~2P resonance state of Mg~–,and a ~2D resonance state of Ca~– have been determined.The trajectories of these resonance states,in conjunction with the complex rotation of the Hamiltonian,were used to determine their wave functions.The electron densities,Fukui functions,and values of the hyper-radius<r^2>were computed from these wave functions.The Fukui functions have negative regions in the valence shell in addition to the inner shell regions,indicating screening effects of the outer temporary electron.Selected configuration interactions with up to quadruple excitations were used along the trajectories and for computing the final wave function.Based on this data,the densities,Fukui functions,and<r^2>were calculated.
文摘The density functional theory and its extension to ensembles of excited states can be formalized as thermodynamics. However, these theories are not unique because one of their key quantities, the kinetic energy density,can be defined in several ways. Usually, the everywhere positive gradient form is applied; however, other forms are also acceptable, provided they integrate to the true kinetic energy. Recently, a kinetic energy density of the ground-state theory maximizing the information entropy has been proposed. Here, ensemble kinetic energy density, leading to extremum information entropy, is derived via constrained search. The corresponding ensemble temperature is found to be constant.
基金Project(52072412)supported by the National Natural Science Foundation of China。
文摘Traditional track dynamic geometric state(TDGS)simulation incurs substantial computational burdens,posing challenges for developing reliability assessment approach that accounts for TDGS.To overcome these,firstly,a simulation-based TDGS model is established,and a surrogate-based model,grid search algorithm-particle swarm optimization-genetic algorithm-multi-output least squares support vector regression,is established.Among them,hyperparameter optimization algorithm’s effectiveness is confirmed through test functions.Subsequently,an adaptive surrogate-based probability density evolution method(PDEM)considering random track geometry irregularity(TGI)is developed.Finally,taking curved train-steel spring floating slab track-U beam as case study,the surrogate-based model trained on simulation datasets not only shows accuracy in both time and frequency domains,but also surpasses existing models.Additionally,the adaptive surrogate-based PDEM shows high accuracy and efficiency,outperforming Monte Carlo simulation and simulation-based PDEM.The reliability assessment shows that the TDGS part peak management indexes,left/right vertical dynamic irregularity,right alignment dynamic irregularity,and track twist,have reliability values of 0.9648,0.9918,0.9978,and 0.9901,respectively.The TDGS mean management index,i.e.,track quality index,has reliability value of 0.9950.These findings show that the proposed framework can accurately and efficiently assess the reliability of curved low-stiffness track-viaducts,providing a theoretical basis for the TGI maintenance.
