“…To this end, we employ the conjugate gradient method (CGM) [13][14][15][16][17] and the discrepancy principle [18] to determine the jet's inlet temperature. The conjugate gradient method with an adjoint equation, also called Alifanov's iterative regularization method, belongs to a class of iterative regularization techniques, which means the regularization procedure is performed during the iterative processes, thus the determination of optimal regularization conditions is not needed.…”