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正则表达式的DFA压缩算法 被引量:6
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作者 杨毅夫 刘燕兵 +2 位作者 刘萍 郭牧怡 郭莉 《通信学报》 EI CSCD 北大核心 2009年第S1期36-42,共7页
基于确定有限自动机(DFA)的正则表达式匹配技术通常用于网络流量实时处理、病毒检测等系统中。随着正则表达式的数量不断增加,DFA的存储空间急剧膨胀。为此,提出了一种有效的DFA压缩算法——簇分割算法,首先总结了DFA的一个结构特征;然... 基于确定有限自动机(DFA)的正则表达式匹配技术通常用于网络流量实时处理、病毒检测等系统中。随着正则表达式的数量不断增加,DFA的存储空间急剧膨胀。为此,提出了一种有效的DFA压缩算法——簇分割算法,首先总结了DFA的一个结构特征;然后依据此特征把DFA分割为3个部分分别存入3个矩阵中,由此构造出2个特征明显的矩阵和1个典型的稀疏矩阵;最后分别对3个矩阵进行压缩。实验表明,簇分割算法在各组数据中均达到了很好的压缩效果,空间压缩率比较稳定。 展开更多
关键词 字符串匹配 自动机压缩 正则表达式 入侵检测
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基于存储优化的多模式串匹配算法 被引量:6
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作者 刘燕兵 刘萍 +1 位作者 谭建龙 郭莉 《计算机研究与发展》 EI CSCD 北大核心 2009年第10期1768-1776,共9页
多模式串匹配算法是网络内容过滤系统的核心技术之一.自动机的存储空间大小和Cache性能是影响多模式串匹配算法速度的关键因素.随着模式串规模的扩大,自动机的巨大存储开销导致现有的串匹配算法性能大幅度下降.从压缩存储空间以提高Cach... 多模式串匹配算法是网络内容过滤系统的核心技术之一.自动机的存储空间大小和Cache性能是影响多模式串匹配算法速度的关键因素.随着模式串规模的扩大,自动机的巨大存储开销导致现有的串匹配算法性能大幅度下降.从压缩存储空间以提高Cache命中率的思想出发,提出了一种对经典SBOM算法的优化策略,它用Suffix Tree代替SBOM算法中的Factor Oracle结构,同时用剪枝的方法将Suffix Tree降低为近似线性的空间复杂度,然后用双数组Trie表示之,以压缩存储空间.与SBOM算法相比,改进算法不仅能够有效地节省存储空间,而且显著地提高了串匹配的速度,非常适合于在线高速匹配的应用环境. 展开更多
关键词 网络内容过滤 多模式串匹配 后缀树 双数组结构 自动机压缩
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Modeling on dynamic recrystallization of aluminium alloy 7050 during hot compression based on cellular automaton 被引量:6
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作者 李军超 谢志远 +1 位作者 李松蒲 臧艳艳 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第3期497-507,共11页
The dynamic recrystallization(DRX) process of hot compressed aluminium alloy 7050 was predicted using cellular automaton(CA) combined with topology deformation. The hot deformatation characteristics of aluminium alloy... The dynamic recrystallization(DRX) process of hot compressed aluminium alloy 7050 was predicted using cellular automaton(CA) combined with topology deformation. The hot deformatation characteristics of aluminium alloy 7050 were investigated by hot uniaxial compression tests in order to obtain the material parameters used in the CA model. The influences of process parameters(strain, strain rate and temperature) on the fraction of DRX and the average recrystallization grain(R-grain) size were investigated and discussed. It is found that larger stain, higher temperature and lower strain rate(less than 0.1 s^(–1)) are beneficial to the increasing fraction of DRX. And the deformation temperature affects the mean R-grain size much more greatly than other parameters. It is also noted that there is a critical strain for the occurrence of DRX which is related to strain rate and temperature. In addition, it is shown that the CA model with topology deformation is able to simulate the microstructural evolution and the flow behavior of aluminium alloy 7050 material under various deformation conditions. 展开更多
关键词 cellular automaton dynamic recrystallization aluminium alloy 7050 flow stress
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Simulation of dynamic recrystallization in 23Co13Ni11Cr3Mo steel using a modified cellular automaton 被引量:1
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作者 黄始全 易幼平 +1 位作者 李蓬川 何海林 《Journal of Central South University》 SCIE EI CAS 2014年第2期454-459,共6页
A modified cellular automaton(CA) program was developed to simulate the process of dynamic recrystallization(DRX) for 23Co13Ni11Cr3Mo ultrahigh strength steel.In this model,influences of deformation parameters on hard... A modified cellular automaton(CA) program was developed to simulate the process of dynamic recrystallization(DRX) for 23Co13Ni11Cr3Mo ultrahigh strength steel.In this model,influences of deformation parameters on hardening rate and solute drag effect were considered.Moreover,an inverse analysis method was proposed for parameters identification of dislocation model and solute drag effect based on the results of isothermal compression tests on Gleeble-1500.Then,simulated microstructures under different deformation conditions were compared with those of experiments.A good agreement is achieved.Furthermore,influences of deformation parameters on microstructure evolution for 23Co13Ni11Cr3Mo steel were investigated in details.High strain is an effective measure to refine grain and improve homogeneity.Meanwhile,the desired deformation parameters are temperature of 1000-1050 °C and strain rate of 0.008-0.01 s-1 for obtaining grains smaller than 22.5 μm. 展开更多
关键词 cellular automaton dynamic recrystallization 23Co13Ni11Cr3Mo ultrahigh strength steel
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