a A0*exp(-E0/(R_const*re.T)) Arrhenius expression A0 2.68e-17[1/s] Frequency factor E0 -243e3[J/mol] Activation energy S re.r_1/re.r_2 Selectivity parameter c_NOm max(re.c_NO,0) Concentration with zero limit c_NH3m max(re.c_NH3,0) Concentration with zero limit