It is an established convention to speak of the fixed stars as a standard unaccelerated reference frame .

把固定恒星说成是标准非照系，这是种已经确惯。

The two dimensional pseudohomogeneous model was often used for the non isothermal, non adiabatic fixed bed reactor that was widely used for the strongly exothermic reactions.

非恒温非绝热固定床反应器广泛应用于强放热反应体系。