Rock residual strength,as an important input parameter,plays an indispensable role in proposing the reasonable and scientific scheme about stope design,underground tunnel excavation and stability evaluation of deep ch...Rock residual strength,as an important input parameter,plays an indispensable role in proposing the reasonable and scientific scheme about stope design,underground tunnel excavation and stability evaluation of deep chambers.Therefore,previous residual strength models of rocks established were reviewed.And corresponding related problems were stated.Subsequently,starting from the effects of bedding and whole life-cycle evolution process,series of triaxial mechanical tests of deep bedded sandstone with five bedding angles were conducted under different confining pressures.Then,six residual strength models considering the effects of bedding and whole life-cycle evolution process were established and evaluated.Finally,a cohesion loss model for determining residual strength of deep bedded sandstone was verified.The results showed that the effects of bedding and whole life-cycle evolution process had both significant influences on the evolution characteristic of residual strength of deep bedded sandstone.Additionally,residual strength parameters:residual cohesion and residual internal friction angle of deep bedded sandstone were not constant,which both significantly changed with increasing bedding angle.Besides,the cohesion loss model was the most suitable for determining and estimating the residual strength of bedded rocks,which could provide more accurate theoretical guidance for the stability control of deep chambers.展开更多
为保证在基于模型的系统工程(model-based systems engineering,MBSE)背景下民机研制的高效过程管理,分析了当前民机研制的过程特征与面临的挑战,在此基础上规划了基于模型的民用飞机研制整体框架与基于模型的过程全寿命周期管理(model-...为保证在基于模型的系统工程(model-based systems engineering,MBSE)背景下民机研制的高效过程管理,分析了当前民机研制的过程特征与面临的挑战,在此基础上规划了基于模型的民用飞机研制整体框架与基于模型的过程全寿命周期管理(model-based process lifecycle management,MBPLM)概念。基于过程模型及其语义结构和类的定义,提出了广泛适用于民机研制全过程的MBPLM方法,并设计相应的并行架构。最后,为提升可操作性,在典型系统民机舱内压力控制系统设计中演示了系统建模过程的管理时序、过程分析评估与异同构模型管理。所提方法可应用于以民用飞机为代表的复杂系统研制,能够在MBSE背景下实现模型开发与过程管理关联与协同,统筹管理研制全寿命周期过程。展开更多
随着社会的进步,统计数据由过去的年度数据变为如今的季度、月度和日度数据,有些以实时交易为基础的超高频金融数据达到了按秒为间隔的频率,这些数据被称为季节时间序列。季节时间序列研究已经成为近十年来经济计量学和统计学中的热点,J...随着社会的进步,统计数据由过去的年度数据变为如今的季度、月度和日度数据,有些以实时交易为基础的超高频金融数据达到了按秒为间隔的频率,这些数据被称为季节时间序列。季节时间序列研究已经成为近十年来经济计量学和统计学中的热点,Journal of Econometrics(1993,volume55)就此问题进行了专题讨论。本文按照历史发展顺序对季节性时间序列理论进行了系统地介绍,并对这一领域的前沿热点问题进行了评述和展望。展开更多
基金Projects(2024YFC3013801,2022YFC3004602)supported by the National Key R&D Program of ChinaProjects(U23B2093,52034009)supported by the National Natural Science Foundation of China。
文摘Rock residual strength,as an important input parameter,plays an indispensable role in proposing the reasonable and scientific scheme about stope design,underground tunnel excavation and stability evaluation of deep chambers.Therefore,previous residual strength models of rocks established were reviewed.And corresponding related problems were stated.Subsequently,starting from the effects of bedding and whole life-cycle evolution process,series of triaxial mechanical tests of deep bedded sandstone with five bedding angles were conducted under different confining pressures.Then,six residual strength models considering the effects of bedding and whole life-cycle evolution process were established and evaluated.Finally,a cohesion loss model for determining residual strength of deep bedded sandstone was verified.The results showed that the effects of bedding and whole life-cycle evolution process had both significant influences on the evolution characteristic of residual strength of deep bedded sandstone.Additionally,residual strength parameters:residual cohesion and residual internal friction angle of deep bedded sandstone were not constant,which both significantly changed with increasing bedding angle.Besides,the cohesion loss model was the most suitable for determining and estimating the residual strength of bedded rocks,which could provide more accurate theoretical guidance for the stability control of deep chambers.
文摘为保证在基于模型的系统工程(model-based systems engineering,MBSE)背景下民机研制的高效过程管理,分析了当前民机研制的过程特征与面临的挑战,在此基础上规划了基于模型的民用飞机研制整体框架与基于模型的过程全寿命周期管理(model-based process lifecycle management,MBPLM)概念。基于过程模型及其语义结构和类的定义,提出了广泛适用于民机研制全过程的MBPLM方法,并设计相应的并行架构。最后,为提升可操作性,在典型系统民机舱内压力控制系统设计中演示了系统建模过程的管理时序、过程分析评估与异同构模型管理。所提方法可应用于以民用飞机为代表的复杂系统研制,能够在MBSE背景下实现模型开发与过程管理关联与协同,统筹管理研制全寿命周期过程。
文摘随着社会的进步,统计数据由过去的年度数据变为如今的季度、月度和日度数据,有些以实时交易为基础的超高频金融数据达到了按秒为间隔的频率,这些数据被称为季节时间序列。季节时间序列研究已经成为近十年来经济计量学和统计学中的热点,Journal of Econometrics(1993,volume55)就此问题进行了专题讨论。本文按照历史发展顺序对季节性时间序列理论进行了系统地介绍,并对这一领域的前沿热点问题进行了评述和展望。
