first-order second moment

基本解释

Based on First-order Second-moment Method(FOSM), a formula for calculating t.
在一次二阶矩法的基础上，推导了计算模糊随机可靠度的具体公式。
The level of environmental risk can be transformed into ordinary probabilistic environmental risk and computed using advanced first-order second-moment method.
最后，将具有灰色概率形式的环境风险度转化成一般的系统失效风险率，进而用改进一阶二矩法进行计算。
In reliability analysis for tunnel lining structure, the simple first-order second-moment method combined with stochastic finite element method is usually employed, but its precision is low.
虽然有很多高精度的结构可靠度分析方法，但大多太复杂或计算时间长，不适用于隧道结构的可靠度计算。