Through the analysis of the sliding failure form of soil mass under the bearing push-extend reamed of Push-extend Multi-under-reamed Pile, in the paper, the law of coulomb-Mohr is used to establish a stress function a...Through the analysis of the sliding failure form of soil mass under the bearing push-extend reamed of Push-extend Multi-under-reamed Pile, in the paper, the law of coulomb-Mohr is used to establish a stress function and the theory of the sliding line is used to establish Prandtl regional stress field, which determines the stress calculating mode of soil mass and provides a theoretical basis for a further study of this type of pile ultimate bearing capacity of soil mass.展开更多
由于光储直流微网输出功率在孤岛模式下受外部环境影响较大,为提高系统的最大功率跟踪特性,采用了正反激变换器的独立光伏发电拓扑结构。针对传统滑模控制在光伏最大功率跟踪(maximum power point tracking,MPPT)中存在的滑模抖振和响...由于光储直流微网输出功率在孤岛模式下受外部环境影响较大,为提高系统的最大功率跟踪特性,采用了正反激变换器的独立光伏发电拓扑结构。针对传统滑模控制在光伏最大功率跟踪(maximum power point tracking,MPPT)中存在的滑模抖振和响应速度慢等问题,提出一种基于改进型超螺旋趋近律的MPPT滑模控制实现方法。该方法利用Sigmoid函数的连续性并与快速终端滑模面相结合,优化了超螺旋趋近律,改善了抖振效果,提高了响应速度,并利用Matlab/Simulink仿真平台与其他控制策略进行对比验证。结果表明:当系统不存在外界扰动时,所提方法均能实现对最大功率点的快速跟踪,同时具有较小的抖振。当辐照度、温度发生变化时,系统具有更好的动态响应速度和抗扰能力。展开更多
文摘Through the analysis of the sliding failure form of soil mass under the bearing push-extend reamed of Push-extend Multi-under-reamed Pile, in the paper, the law of coulomb-Mohr is used to establish a stress function and the theory of the sliding line is used to establish Prandtl regional stress field, which determines the stress calculating mode of soil mass and provides a theoretical basis for a further study of this type of pile ultimate bearing capacity of soil mass.
文摘由于光储直流微网输出功率在孤岛模式下受外部环境影响较大,为提高系统的最大功率跟踪特性,采用了正反激变换器的独立光伏发电拓扑结构。针对传统滑模控制在光伏最大功率跟踪(maximum power point tracking,MPPT)中存在的滑模抖振和响应速度慢等问题,提出一种基于改进型超螺旋趋近律的MPPT滑模控制实现方法。该方法利用Sigmoid函数的连续性并与快速终端滑模面相结合,优化了超螺旋趋近律,改善了抖振效果,提高了响应速度,并利用Matlab/Simulink仿真平台与其他控制策略进行对比验证。结果表明:当系统不存在外界扰动时,所提方法均能实现对最大功率点的快速跟踪,同时具有较小的抖振。当辐照度、温度发生变化时,系统具有更好的动态响应速度和抗扰能力。
