Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This...Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.展开更多
Ultrasonic transmitting, receiving and amplifying circuits are designed. Thereceived signals are sampled with the high speed ADC (analog-to-digital converter), and dealt withthe DSP (digital signal processing). A forw...Ultrasonic transmitting, receiving and amplifying circuits are designed. Thereceived signals are sampled with the high speed ADC (analog-to-digital converter), and dealt withthe DSP (digital signal processing). A forward-backward IIR (infinitive impulse response) filterwith no delay is designed to filter the sampled data, and series A and B are achieved by narrow andwide band filtering, respectively. In series A, the start point of the cycle first exceeding thethreshold is calculated accuratelyby interpolation, and the start cycle is detected by fittingcycles in series A and its inversion A' to cycles in B with variance analysis. Therefore, the startpoint of the start cycle is calculated precisely. By deriving the relationships between the traveltime in the opposite directions of three axes and the airflow velocities, the wind velocity anddirection are calculated. Experiments show that the reliability and the precision are improved, andthe circuits are simplified.展开更多
建筑信息建模(Building Information Modeling,BIM)起源于20世纪70年代的美国,由美国乔治亚理工大学建筑与计算机学院的查克伊士曼博士提出。鉴于目前国内外对于BIM的概念得不到一致的定义,给许多BIM的初学者带来困扰,给BIM在国内的推...建筑信息建模(Building Information Modeling,BIM)起源于20世纪70年代的美国,由美国乔治亚理工大学建筑与计算机学院的查克伊士曼博士提出。鉴于目前国内外对于BIM的概念得不到一致的定义,给许多BIM的初学者带来困扰,给BIM在国内的推广应用带来了阻碍。在查阅大量国外多方对于BIM概念的权威解释,总结出BIM的内涵意义。展开更多
针对传统的DSP代码开发周期较长、效率低等缺点,详细介绍了一种快速、高效的DSP代码开发流程。利用MAT-LAB、S imu link、Real-Tim e W orkshop、DSP B locksets工具箱和TI公司的开发工具CCS IDE,在S imu link环境下,用图形化的方式设计...针对传统的DSP代码开发周期较长、效率低等缺点,详细介绍了一种快速、高效的DSP代码开发流程。利用MAT-LAB、S imu link、Real-Tim e W orkshop、DSP B locksets工具箱和TI公司的开发工具CCS IDE,在S imu link环境下,用图形化的方式设计DSP程序,实现代码的自动生成。完成了DSP系统设计到实施的无缝集成,缩短了开发周期。利用该方法所设计的直流力矩电机控制系统已在TMS320F2812开发板上顺利运行。展开更多
基金the financial support by the National Natural Science Foundation of China(Grant No.52108397)“Xiaohe”Science and Technology Talent Special Project(Grant No.2024 TJ-X06)Water Resources Science and Technology Project of Hunan Province(Grant No.XSKJ2023059-41).
文摘Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.
文摘Ultrasonic transmitting, receiving and amplifying circuits are designed. Thereceived signals are sampled with the high speed ADC (analog-to-digital converter), and dealt withthe DSP (digital signal processing). A forward-backward IIR (infinitive impulse response) filterwith no delay is designed to filter the sampled data, and series A and B are achieved by narrow andwide band filtering, respectively. In series A, the start point of the cycle first exceeding thethreshold is calculated accuratelyby interpolation, and the start cycle is detected by fittingcycles in series A and its inversion A' to cycles in B with variance analysis. Therefore, the startpoint of the start cycle is calculated precisely. By deriving the relationships between the traveltime in the opposite directions of three axes and the airflow velocities, the wind velocity anddirection are calculated. Experiments show that the reliability and the precision are improved, andthe circuits are simplified.
文摘建筑信息建模(Building Information Modeling,BIM)起源于20世纪70年代的美国,由美国乔治亚理工大学建筑与计算机学院的查克伊士曼博士提出。鉴于目前国内外对于BIM的概念得不到一致的定义,给许多BIM的初学者带来困扰,给BIM在国内的推广应用带来了阻碍。在查阅大量国外多方对于BIM概念的权威解释,总结出BIM的内涵意义。
文摘针对传统的DSP代码开发周期较长、效率低等缺点,详细介绍了一种快速、高效的DSP代码开发流程。利用MAT-LAB、S imu link、Real-Tim e W orkshop、DSP B locksets工具箱和TI公司的开发工具CCS IDE,在S imu link环境下,用图形化的方式设计DSP程序,实现代码的自动生成。完成了DSP系统设计到实施的无缝集成,缩短了开发周期。利用该方法所设计的直流力矩电机控制系统已在TMS320F2812开发板上顺利运行。
