The variation at the lower solar elevation is caused by the cosine response of the instrument.
而太阳高度角较低时此值的变化，主要由仪器的余弦响应所引起。
2
The strain_stress variation measuring experiments of steel_cable_stayed bridge model under loading condition were done by using fiber optic strain sensing instrument.
采用光纤应变测量仪对桥梁钢索的应力应变在载荷情况下的变化进行了实验研究。
3
For Shanghai power grid, which has large short circuit capacity and short electrical distance, a method using imported instrument to test power frequency variation distance protection is presented.