other Mathematical Modeling and Applications of OR Mathematical Modeling and Applications of OR پژوهشی Original <span style="font-size:11pt"><span style="line-height:normal"><span style="text-autospace:none"><span style="font-family:&quot;Times New Roman&quot;,serif"><i><span style="font-size:10.0pt"><span style="letter-spacing:-.25pt">This paper develops slacks-based measure (SBM) and additive SBM (ASBM) to evaluate efficiency of decision making units (DMUs) in a two-stage structure with undesirable outputs and feedback variables from the internal perspective. The SBM model is linearized &nbsp;for a specific weight and the ASBM model is reformulated as a second order cone program. The target values for all inputs, outputs (both desirable and undesirable) and intermediate products are &nbsp;provided. This study shows that unlike the SBM model, ASBM can be adapted to the preference of the decision maker by selecting the weights to aggregate stages in the network.</span></span></i></span></span></span></span><br> &nbsp; Network data envelopment analysis, feedback, undesirable output, SOCP. 37 53 http://iors.ir/journal/browse.php?a_code=A-10-1422-44&slc_lang=other&sid=1 Narges Torabi Golsefid Narges Torabi Golsefid nargestorabi91@gmail.com 1111111111 1111111111 No University of Guilan - - Rasht, Iran University of Guilan - - Rasht, Iran Maziar Salahi Maziar Salahi salahim@guilan.ac.ir 1111111111 1111111111 Yes University of Guilan - - Rasht, Iran University of Guilan - - Rasht, Iran