Purpose–This paper focuses on studying the reliability allocation for the railway system,aiming to improve the overall reliability of the railway system and ensure safety operation.Design/methodology/approach–In vie...Purpose–This paper focuses on studying the reliability allocation for the railway system,aiming to improve the overall reliability of the railway system and ensure safety operation.Design/methodology/approach–In view of the complex structure of the railway system,involving many subsystems,this paper analyzes the close dynamic coupling effect between railway subsystems.Based on this,taking the railway system failure as the top event,a fault tree is constructed in this paper.Then,a reliability allocation method based on the fault tree is employed to allocate the reliability index.Finally,a numerical experiment is implemented to show the performance of the reliability allocation method.Findings–The results showed that each subsystem needs to improve its reliability to meet the specified railway system reliability requirements,and the traction power supply system is the most important subsystem,which is the most efficient in improving the reliability of the railway system.Originality/value–For the first time,starting from a holistic perspective of the system,reliability allocation is carried out based on the importance of each railway subsystem.展开更多
We study CFG parse tree enumeration in this paper. By dividing the set of all parse trees into infinite hierarchies according to height of parse tree, the hierarchical lexicographic order on the set of parse trees is ...We study CFG parse tree enumeration in this paper. By dividing the set of all parse trees into infinite hierarchies according to height of parse tree, the hierarchical lexicographic order on the set of parse trees is established. Then grammar-based algorithms for counting and enumerating CFG parse trees in this order are presented. To generate a parse tree of height n, the time complexity is O（n）. If τ is a lowest parse tree for its yield, then O（n） =O（｜｜τ｜｜ ＋ 1）, where ｜｜τ｜｜ is the length of the sentence （yield） generated by τ. The sentence can be obtained as a by-product of the parse tree. To compute sentence from its parse tree （needn＇t be lowest one）, the time complexity is O（node）＋O（｜｜τ｜｜ ＋ 1）, where node is the number of non-leaf nodes of parse tree τ. To generate both a complete lowest parse tree and its yield at the same time, the time complexity is O（｜｜τ｜｜ ＋ 1）.展开更多
Introduction:Southern Xinjiang Uygur Autonomous Region,China,experiences a substantial tuberculosis burden,yet comprehensive genotypic characterization of Mycobacterium tuberculosis strains in this region remains limi...Introduction:Southern Xinjiang Uygur Autonomous Region,China,experiences a substantial tuberculosis burden,yet comprehensive genotypic characterization of Mycobacterium tuberculosis strains in this region remains limited.Methods:This study collected Mycobacterium tuberculosis strains and corresponding epidemiological data from patients between 2021 and 2023.Bacterial isolates underwent whole-genome sequencing using the Illumina next-generation sequencing platform.We constructed phylogenetic trees using iqtree and generated minimum spanning trees based on GraphSNP analysis,applying a clustering threshold of 12 single nucleotide polymorphisms(SNPs)to identify transmission clusters.Results:Lineage 2 emerged as the predominant strain type,accounting for the majority of isolates,followed by Lineages 4 and 3.Notably,Lineage 2 demonstrated significantly elevated clustering rates compared to other lineages.Genetic diversity analysis revealed that Lineage 2 strains exhibited the most limited intra-lineage variation,whereas Lineage 3 displayed the greatest genetic heterogeneity among strains.Conclusion:Our investigation demonstrates substantial genetic polymorphism among Mycobacterium tuberculosis strains circulating in southern Xinjiang.These findings highlight the critical need for enhanced transmission control strategies,with particular emphasis on intensive surveillance and prevention measures targeting Lineage 2 strains.展开更多
Generally speaking, it is impossible for a wire-frame to define a 3D object uniquely. But wire-frame as a graphics medium is still applied in some industrial areas. A sufficient condition is presented in this paper. I...Generally speaking, it is impossible for a wire-frame to define a 3D object uniquely. But wire-frame as a graphics medium is still applied in some industrial areas. A sufficient condition is presented in this paper. If this condition is satisfied by a wire-frame, then the wire-frame can represent a 3D object uniquely The result is applied to manufacturing of progressive stripe.展开更多
基金supported by the Research Project of China Academy of Railway Sciences Corporation Limited under Grant 2023YJ252.
文摘Purpose–This paper focuses on studying the reliability allocation for the railway system,aiming to improve the overall reliability of the railway system and ensure safety operation.Design/methodology/approach–In view of the complex structure of the railway system,involving many subsystems,this paper analyzes the close dynamic coupling effect between railway subsystems.Based on this,taking the railway system failure as the top event,a fault tree is constructed in this paper.Then,a reliability allocation method based on the fault tree is employed to allocate the reliability index.Finally,a numerical experiment is implemented to show the performance of the reliability allocation method.Findings–The results showed that each subsystem needs to improve its reliability to meet the specified railway system reliability requirements,and the traction power supply system is the most important subsystem,which is the most efficient in improving the reliability of the railway system.Originality/value–For the first time,starting from a holistic perspective of the system,reliability allocation is carried out based on the importance of each railway subsystem.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 60273023, 60721061)
文摘We study CFG parse tree enumeration in this paper. By dividing the set of all parse trees into infinite hierarchies according to height of parse tree, the hierarchical lexicographic order on the set of parse trees is established. Then grammar-based algorithms for counting and enumerating CFG parse trees in this order are presented. To generate a parse tree of height n, the time complexity is O（n）. If τ is a lowest parse tree for its yield, then O（n） =O（｜｜τ｜｜ ＋ 1）, where ｜｜τ｜｜ is the length of the sentence （yield） generated by τ. The sentence can be obtained as a by-product of the parse tree. To compute sentence from its parse tree （needn＇t be lowest one）, the time complexity is O（node）＋O（｜｜τ｜｜ ＋ 1）, where node is the number of non-leaf nodes of parse tree τ. To generate both a complete lowest parse tree and its yield at the same time, the time complexity is O（｜｜τ｜｜ ＋ 1）.
基金Supported by the“Tianshan Talents”Medical and Health High-level Talent Training Program(TSYC202301B166)the Natural Science Foundation of Xinjiang Uygur Autonomous Region Project(2023D01C57),and grant WJW2024-087.
文摘Introduction:Southern Xinjiang Uygur Autonomous Region,China,experiences a substantial tuberculosis burden,yet comprehensive genotypic characterization of Mycobacterium tuberculosis strains in this region remains limited.Methods:This study collected Mycobacterium tuberculosis strains and corresponding epidemiological data from patients between 2021 and 2023.Bacterial isolates underwent whole-genome sequencing using the Illumina next-generation sequencing platform.We constructed phylogenetic trees using iqtree and generated minimum spanning trees based on GraphSNP analysis,applying a clustering threshold of 12 single nucleotide polymorphisms(SNPs)to identify transmission clusters.Results:Lineage 2 emerged as the predominant strain type,accounting for the majority of isolates,followed by Lineages 4 and 3.Notably,Lineage 2 demonstrated significantly elevated clustering rates compared to other lineages.Genetic diversity analysis revealed that Lineage 2 strains exhibited the most limited intra-lineage variation,whereas Lineage 3 displayed the greatest genetic heterogeneity among strains.Conclusion:Our investigation demonstrates substantial genetic polymorphism among Mycobacterium tuberculosis strains circulating in southern Xinjiang.These findings highlight the critical need for enhanced transmission control strategies,with particular emphasis on intensive surveillance and prevention measures targeting Lineage 2 strains.
基金This work is supported by the National Natural Science Foundation of China (No.6612551).
文摘Generally speaking, it is impossible for a wire-frame to define a 3D object uniquely. But wire-frame as a graphics medium is still applied in some industrial areas. A sufficient condition is presented in this paper. If this condition is satisfied by a wire-frame, then the wire-frame can represent a 3D object uniquely The result is applied to manufacturing of progressive stripe.
