@article { author = {Maedeh, GholamAzad and Jafar, Pourmahmoud}, title = {Evaluating the Congestion Effect in the Two-Stage Structures by NDEA Models}, journal = {Journal of Modern Operations Research}, volume = {1}, number = {2}, pages = {-}, year = {2021}, publisher = {AJA Command and Staff University}, issn = {2783-1493}, eissn = {2783-1493}, doi = {}, abstract = {Congestion is an important issue in economics and data envelopment analysis (DEA). It occurs when one or more outputs can be increased by reducing one or more inputs, without worsening any other input or output. In recent years, there have been various studies dealt with two-stage production systems by DEA models. These systems consume some inputs in their first stage to produce some intermediate outputs which are used as the inputs of the second stage in producing final output.  So far, it is not much attention to the existence of the congestion effect in these structures. In this article, we have focused on a congestion effect on the two-stage structures via network DEA models. In addition, this study proposes a new method for measuring congestion in divisions of the network. This model can evaluate congestion in the network structure and identify that which factors cause of the congestion}, keywords = {Congestion,Division,Two-stage structure,DEA}, url = {https://www.jmor.ir/article_240075.html}, eprint = {} } @article { author = {P, Zamani and M.M, Shafiei Zadeh}, title = {The Position of Multiobjective Programming Methods in Fuzzy Data Envelopment Analysis}, journal = {Journal of Modern Operations Research}, volume = {1}, number = {2}, pages = {-}, year = {2021}, publisher = {AJA Command and Staff University}, issn = {2783-1493}, eissn = {2783-1493}, doi = {}, abstract = {Traditional Data Envelopment Analysis (DEA) models evaluate the efficiency ofdecision making units (DMUs) with common crisp input and output data. However, the data in real applications are often imprecise or ambiguous. This paper transforms fuzzy fractional DEA model which is constructed using fuzzy arithmetic, into the conventional crisp model. This transformation is performed considering the goal programming that is one of the Multi Objective Programming (MOP) methods. Therefore, in this research the one linear programming model measures the fuzzy efficiencies of DMUs with fuzzy input and fuzzy output data}, keywords = {Data Envelopment Analysis,Fuzzy input and fuzzy output data,Fuzzy efficiency,Multiobjective programming,Goal programming}, url = {https://www.jmor.ir/article_240081.html}, eprint = {} } @article { author = {Gholamnezhad, Pezhman}, title = {A random forest approach on Multi-objective flexible job-shop scheduling problem}, journal = {Journal of Modern Operations Research}, volume = {1}, number = {2}, pages = {-}, year = {2021}, publisher = {AJA Command and Staff University}, issn = {2783-1493}, eissn = {2783-1493}, doi = {}, abstract = {The traditional job-shop scheduling problem (JSP) requires the allocation of N independent jobs on M machines. In most flexible job-shop scheduling problem assumptions that all machines are always available. But unexpected machine failure that is called the random machine break downs is not considered. So, the stability of schedules can be computed. In this paper, an inversed model-based on random forest method in which a Gaussian process and variable importance random forest algorithm are used for mapping non-dominated solutions from the objective space (PF) to the decision space (PS). Then this proposed method is applied on an FJSP with random machine breakdowns (RMBs) which the stability of the schedule is detected by the deviation of each job time preschedule and real schedule. The proposed algorithm has been tested on the benchmark test suite for flexible job-shop scheduling problem and has compared with IM-MOEA and NSGA-II and indicates that the proposed method is a competitive and promising approach.}, keywords = {Flexible job-shop scheduling problem,stability,Random machine breakdowns,Random forest variable importance,Multi-objective optimization}, url = {https://www.jmor.ir/article_246817.html}, eprint = {} }