The vibration frequency of box gird is usually calculated by the elementarybeam theory, but it will lead to a large error because of the existence of shear lag effect and shear deformation.
由于剪力滞效应及剪切变形的存在，箱梁的弯曲振动频率按照初等梁理论计算往往存在较大的误差。
2
The elementary exposure pattern of a variable rectangular electron beam exposure machine is a rectangle.
可变矩形电子束曝光机的基本曝光图形是矩形。
3
Coupled laser array, which realizes phase locking of elementary lasers with evanescent waves coupling, is a promising scheme to realize coherent beam combination.