Based on the first-order shear deformation theory,a 3-node co-rotational triangular finite element formulation is developed for large deformation modeling of non-smooth,folded and multi-shell laminated composite struc...Based on the first-order shear deformation theory,a 3-node co-rotational triangular finite element formulation is developed for large deformation modeling of non-smooth,folded and multi-shell laminated composite structures.The two smaller components of the mid-surface normal vector of shell at a node are defined as nodal rotational variables in the co-rotational local coordinate system.In the global coordinate system,two smaller components of one vector,together with the smallest or second smallest component of another vector,of an orthogonal triad at a node on a non-smooth intersection of plates and/or shells are defined as rotational variables,whereas the two smaller components of the mid-surface normal vector at a node on the smooth part of the plate or shell(away from non-smooth intersections)are defined as rotational variables.All these vectorial rotational variables can be updated in an additive manner during an incremental solution procedure,and thus improve the computational efficiency in the nonlinear solution of these composite shell structures.Due to the commutativity of all nodal variables in calculating of the second derivatives of the local nodal variables with respect to global nodal variables,and the second derivatives of the strain energy functional with respect to local nodal variables,symmetric tangent stiffness matrices in local and global coordinate systems are obtained.To overcome shear locking,the assumed transverse shear strains obtained from the line-integration approach are employed.The reliability and computational accuracy of the present 3-node triangular shell finite element are verified through modeling two patch tests,several smooth and non-smooth laminated composite shells undergoing large displacements and large rotations.展开更多
运动目标检测主要是从序列图像中将变化区域从背景中分割出来,它影响着运动目标能否正确地分类和跟踪。因此,运动目标检测是智能视频监控技术中的关键问题之一。有限线积分变换(finite line integral transform,FLIT)作为近年来一种多...运动目标检测主要是从序列图像中将变化区域从背景中分割出来,它影响着运动目标能否正确地分类和跟踪。因此,运动目标检测是智能视频监控技术中的关键问题之一。有限线积分变换(finite line integral transform,FLIT)作为近年来一种多尺度几何分析的新方法,能有效提取图像中的线性特征。检测方法是在FLIT的基础上再结合背景差法来实现的。具体而言,先对图像序列中的每帧图像(包括参考帧)作固定模板下的FLIT,再用当前帧的FLIT减去参考帧的FLIT,然后对不同方向提取的运动目标信息进行综合,最后采用数学形态学的相关处理来消除噪声。实验结果表明,使用该方法可以承受整体的或局部的、缓慢的或突变的光线变化,能有效地检测出运动目标。展开更多
通过分析隔离式断路器与电子互感器一体化现有的两种方案所存在的技术问题,并结合现有两种方案的技术优点,提出了一种新型的组合方案,为隔离式断路器与电子互感器一体化设计提供了新的思路,以高度集成化结构方案进行仿真,为工程设计提...通过分析隔离式断路器与电子互感器一体化现有的两种方案所存在的技术问题,并结合现有两种方案的技术优点,提出了一种新型的组合方案,为隔离式断路器与电子互感器一体化设计提供了新的思路,以高度集成化结构方案进行仿真,为工程设计提供了技术参考。结合现有110 k V电子互感器产品与隔离式断路器组合为例分析计算,为该新型组合方案的可行性提供了技术支持。主要研究了新型组合方案中高度集成化原则下电子互感器与隔离式断路器相互之间绝缘的影响。利用ANSYS有限元分析法,分别对隔离断路器合闸状态与分闸状态下电子互感器与隔离断路器各自独立的内外电场值及电场线分布趋势进行了仿真分析,从而得出在无源电子互感器与隔离断路器高度组合的条件下,相互的电场影响极小,不影响各自的正常运行,易于实现一体化。展开更多
基金This work was supported by National Natural Science Foundation of China under Grant 11672266.
文摘Based on the first-order shear deformation theory,a 3-node co-rotational triangular finite element formulation is developed for large deformation modeling of non-smooth,folded and multi-shell laminated composite structures.The two smaller components of the mid-surface normal vector of shell at a node are defined as nodal rotational variables in the co-rotational local coordinate system.In the global coordinate system,two smaller components of one vector,together with the smallest or second smallest component of another vector,of an orthogonal triad at a node on a non-smooth intersection of plates and/or shells are defined as rotational variables,whereas the two smaller components of the mid-surface normal vector at a node on the smooth part of the plate or shell(away from non-smooth intersections)are defined as rotational variables.All these vectorial rotational variables can be updated in an additive manner during an incremental solution procedure,and thus improve the computational efficiency in the nonlinear solution of these composite shell structures.Due to the commutativity of all nodal variables in calculating of the second derivatives of the local nodal variables with respect to global nodal variables,and the second derivatives of the strain energy functional with respect to local nodal variables,symmetric tangent stiffness matrices in local and global coordinate systems are obtained.To overcome shear locking,the assumed transverse shear strains obtained from the line-integration approach are employed.The reliability and computational accuracy of the present 3-node triangular shell finite element are verified through modeling two patch tests,several smooth and non-smooth laminated composite shells undergoing large displacements and large rotations.
文摘运动目标检测主要是从序列图像中将变化区域从背景中分割出来,它影响着运动目标能否正确地分类和跟踪。因此,运动目标检测是智能视频监控技术中的关键问题之一。有限线积分变换(finite line integral transform,FLIT)作为近年来一种多尺度几何分析的新方法,能有效提取图像中的线性特征。检测方法是在FLIT的基础上再结合背景差法来实现的。具体而言,先对图像序列中的每帧图像(包括参考帧)作固定模板下的FLIT,再用当前帧的FLIT减去参考帧的FLIT,然后对不同方向提取的运动目标信息进行综合,最后采用数学形态学的相关处理来消除噪声。实验结果表明,使用该方法可以承受整体的或局部的、缓慢的或突变的光线变化,能有效地检测出运动目标。
文摘通过分析隔离式断路器与电子互感器一体化现有的两种方案所存在的技术问题,并结合现有两种方案的技术优点,提出了一种新型的组合方案,为隔离式断路器与电子互感器一体化设计提供了新的思路,以高度集成化结构方案进行仿真,为工程设计提供了技术参考。结合现有110 k V电子互感器产品与隔离式断路器组合为例分析计算,为该新型组合方案的可行性提供了技术支持。主要研究了新型组合方案中高度集成化原则下电子互感器与隔离式断路器相互之间绝缘的影响。利用ANSYS有限元分析法,分别对隔离断路器合闸状态与分闸状态下电子互感器与隔离断路器各自独立的内外电场值及电场线分布趋势进行了仿真分析,从而得出在无源电子互感器与隔离断路器高度组合的条件下,相互的电场影响极小,不影响各自的正常运行,易于实现一体化。
