Model checking based on linear temporal logic reduces the false negative rate of misuse detection.However,linear temporal logic formulae cannot be used to describe concurrent attacks and piecewise attacks.So there is ...Model checking based on linear temporal logic reduces the false negative rate of misuse detection.However,linear temporal logic formulae cannot be used to describe concurrent attacks and piecewise attacks.So there is still a high rate of false negatives in detecting these complex attack patterns.To solve this problem,we use interval temporal logic formulae to describe concurrent attacks and piecewise attacks.On this basis,we formalize a novel algorithm for intrusion detection based on model checking interval temporal logic.Compared with the method based on model checking linear temporal logic,the new algorithm can find unknown succinct attacks.The simulation results show that the new method can effectively reduce the false negative rate of concurrent attacks and piecewise attacks.展开更多
利用变量节点符号可靠度在迭代过程中的分布特征,提出了一种基于可靠度差值特征的自适应判决多元低密度奇偶校验(Low Density Parity Check, LDPC)译码算法。整个迭代过程划分为两个阶段,针对不同阶段节点可靠度的差值特征分别采用不同...利用变量节点符号可靠度在迭代过程中的分布特征,提出了一种基于可靠度差值特征的自适应判决多元低密度奇偶校验(Low Density Parity Check, LDPC)译码算法。整个迭代过程划分为两个阶段,针对不同阶段节点可靠度的差值特征分别采用不同的判决策略:前期阶段,采用传统的基于最大可靠度的判决策略;后期阶段,根据最大、次大可靠度之间的差值特征,设计自适应的码元符号判决策略。仿真结果表明,所提算法在相当的译码复杂度前提下,能获得0.15~0.4 dB的性能增益。同时,对于列重较小的LDPC码,具有更低的译码错误平层。展开更多
The soundness is a very important criterion for the correctness of the workflow. Specifying the soundness with Computation Tree Logic （CTL） allows us to verify the soundness with symbolic model checkers. Therefore t...The soundness is a very important criterion for the correctness of the workflow. Specifying the soundness with Computation Tree Logic （CTL） allows us to verify the soundness with symbolic model checkers. Therefore the state explosion problem in verifying soundness can be overcome efficiently. When the property is not satisfied by the system, model checking can give a counter-example, which can guide us to correct the workflow. In addition, relaxed soundness is another important criterion for the workflow. We also prove that Computation Tree Logic ＊ （CTL ＊ ） can be used to character the relaxed soundness of the workflow.展开更多
A multi-agent based transport system is modeled by timed automata model extended with clock variables. The correctness properties of safety and liveness of this model are verified by timed automata based UPPAAL. Agent...A multi-agent based transport system is modeled by timed automata model extended with clock variables. The correctness properties of safety and liveness of this model are verified by timed automata based UPPAAL. Agents have a degree of control on their own actions, have their own threads of control, and under some circumstances they are also able to take decisions. Therefore they are autonomous. The multi-agent system is modeled as a network of timed automata based agents supported by clock variables. The representation of agent requirements based on mathematics is helpful in precise and unambiguous specifications, thereby ensuring correctness. This formal representation of requirements provides a way for logical reasoning about the artifacts produced. We can be systematic and precise in assessing correctness by rigorously specifying the functional requirements.展开更多
介绍ArcGIS Data Reviewer基本功能和特性,对其应用于林业地理信息矢量数据质量检查,如图斑重复、重叠,图斑间有间隙、多部件、狭长面、急锐角化、漏绘等空间关系,以及属性字段之间的逻辑性检查等的方法和步骤,举例进行了详细叙述,可为...介绍ArcGIS Data Reviewer基本功能和特性,对其应用于林业地理信息矢量数据质量检查,如图斑重复、重叠,图斑间有间隙、多部件、狭长面、急锐角化、漏绘等空间关系,以及属性字段之间的逻辑性检查等的方法和步骤,举例进行了详细叙述,可为该软件模块的使用提供参考。展开更多
为促进芯片国产化进程,解决低密度奇偶校验(Low density parity check,LDPC)码译码效率低下的问题,以空间数据咨询委员会(The consultative committee for space data systems,CCSDS)标准下的、应用于近地空间(8176,7154)的LDPC码为研...为促进芯片国产化进程,解决低密度奇偶校验(Low density parity check,LDPC)码译码效率低下的问题,以空间数据咨询委员会(The consultative committee for space data systems,CCSDS)标准下的、应用于近地空间(8176,7154)的LDPC码为研究对象,根据归一化最小和译码(Normalized minimum sum,NMS)算法理论,设计了一种尺度因子可改变的LDPC译码器。首先,利用Vivado软件编写寄存器传输级(Register-transfer level,RTL)代码并进行功能仿真。其次,利用Design Compiler工具完成RTL级代码的综合,以生成物理设计需要的门级网表,并通过Innovus工具完成对的芯片后端自动布线(Auto placement route,APR)阶段的设计。在利用Prime Time和Calibre软件分别进行时序检查和物理验证时发现,存在时序违例1132条,设计规则违例647条。以不断迭代的方式进行修复,最终消除了违例,时序和物理设计均满足要求,并生成了GDS II文件。该设计可为芯片国产化生产提供新的思路。展开更多
基金supported by National Natural Science Foundation of China under Grant No. 61003079
文摘Model checking based on linear temporal logic reduces the false negative rate of misuse detection.However,linear temporal logic formulae cannot be used to describe concurrent attacks and piecewise attacks.So there is still a high rate of false negatives in detecting these complex attack patterns.To solve this problem,we use interval temporal logic formulae to describe concurrent attacks and piecewise attacks.On this basis,we formalize a novel algorithm for intrusion detection based on model checking interval temporal logic.Compared with the method based on model checking linear temporal logic,the new algorithm can find unknown succinct attacks.The simulation results show that the new method can effectively reduce the false negative rate of concurrent attacks and piecewise attacks.
基金Supported by the National Natural Science Foun-dation of China (60573046)
文摘The soundness is a very important criterion for the correctness of the workflow. Specifying the soundness with Computation Tree Logic （CTL） allows us to verify the soundness with symbolic model checkers. Therefore the state explosion problem in verifying soundness can be overcome efficiently. When the property is not satisfied by the system, model checking can give a counter-example, which can guide us to correct the workflow. In addition, relaxed soundness is another important criterion for the workflow. We also prove that Computation Tree Logic ＊ （CTL ＊ ） can be used to character the relaxed soundness of the workflow.
文摘A multi-agent based transport system is modeled by timed automata model extended with clock variables. The correctness properties of safety and liveness of this model are verified by timed automata based UPPAAL. Agents have a degree of control on their own actions, have their own threads of control, and under some circumstances they are also able to take decisions. Therefore they are autonomous. The multi-agent system is modeled as a network of timed automata based agents supported by clock variables. The representation of agent requirements based on mathematics is helpful in precise and unambiguous specifications, thereby ensuring correctness. This formal representation of requirements provides a way for logical reasoning about the artifacts produced. We can be systematic and precise in assessing correctness by rigorously specifying the functional requirements.
文摘为促进芯片国产化进程,解决低密度奇偶校验(Low density parity check,LDPC)码译码效率低下的问题,以空间数据咨询委员会(The consultative committee for space data systems,CCSDS)标准下的、应用于近地空间(8176,7154)的LDPC码为研究对象,根据归一化最小和译码(Normalized minimum sum,NMS)算法理论,设计了一种尺度因子可改变的LDPC译码器。首先,利用Vivado软件编写寄存器传输级(Register-transfer level,RTL)代码并进行功能仿真。其次,利用Design Compiler工具完成RTL级代码的综合,以生成物理设计需要的门级网表,并通过Innovus工具完成对的芯片后端自动布线(Auto placement route,APR)阶段的设计。在利用Prime Time和Calibre软件分别进行时序检查和物理验证时发现,存在时序违例1132条,设计规则违例647条。以不断迭代的方式进行修复,最终消除了违例,时序和物理设计均满足要求,并生成了GDS II文件。该设计可为芯片国产化生产提供新的思路。
