second order moments 二阶矩 ; 二阶矩模型
second-order moments matrix 二阶矩矩阵
first and second order moments 前两阶矩
second-order moments of intensity 强度二阶矩
It is shown that the expressions of the above parameters for Lorentz beams obtained by second-order moments of the Wigner distribution are the same as those by intensity moments.
结果表明,利用Wigner分布函数二阶矩和利用强度矩得到的洛伦兹光束束腰、远场发散角表达式是一致的。
参考来源 - 洛伦兹光束传输特性的研究·2,447,543篇论文数据，部分数据来源于NoteExpress
The force and moment exerted on the solid body are expressed as the rate of change of the first-and second-order kinetic vorticity moments, respectively.
作用在任意运动物体（系）上的力和力矩可以分别表示成流场中动力学涡量的一阶矩和二阶矩随时间的变化率。
The characteristics of three dimensional astigmatic beams were discussed by using their second order intensity moments.
采用光束的二阶强度矩的方法讨论三维像散光束的光束特性。
This study calculated the statistical moments of settlement for shallow foundation by using second-order perturbation stochastic finite element method.
笔者探讨了这一方法，考虑土性分布参数和荷载变异性，用二阶摄动随机有限元法进行了浅地基沉降的概率分析。
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