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دسترسی آزاد مقاله
1 - Green Reverse Supply Chain on the Way of Optimization: A Case of Dairy Sector
zeinab zarrat dakheli parast hassan haleh soroush avakh darestani hamzeh amin tahmasbiThe achievement of chain greening objectives, besides costs minimization, can be realized when both reverse and forward flows are taken into account in the design of the supply chain network. It is possible to decrease the chain costs and have a greener chain by means o چکیده کاملThe achievement of chain greening objectives, besides costs minimization, can be realized when both reverse and forward flows are taken into account in the design of the supply chain network. It is possible to decrease the chain costs and have a greener chain by means of different strategies like vehicular routing, hub location, inventory management, and simultaneous pickup and delivery. The development of green reverse supply chains and the practice of the above-mentioned strategies are becoming increasing important with the appearance of perishable product chains. Considering the mentioned points, the current study attempts to design a green reverse supply chain network for the purpose of distributing dairy items such as yogurt drink where the strategy of simultaneous pickup and delivery under uncertainty is taken into consideration. This model focuses on the simultaneous costs reduction and also decrease of lost demands and presents a fuzzy solution for solving the bi-objective model. پرونده مقاله -
دسترسی آزاد مقاله
2 - Nurse Scheduling Problem by Considering Fuzzy Modeling Approach to Treat Uncertainty on Nurses’ Preferences for Working Shifts and Weekends off
Hamed Jafari Hassan HalehNowadays, the nurse scheduling problem (NSP) has attracted a great amount of attentions. In this problem,the nurses are scheduled to be assigned to the shifts by considering the required nurses for each day during the planning horizon. In the current study, a bi-objecti چکیده کاملNowadays, the nurse scheduling problem (NSP) has attracted a great amount of attentions. In this problem,the nurses are scheduled to be assigned to the shifts by considering the required nurses for each day during the planning horizon. In the current study, a bi-objective mathematical model is formulated in order to maximize the preferences of the nurses to work on the shifts in addition to be off on the weekends. In real-world problems, higher quality schedules are provided considering the uncertainty. In this point of view, we investigate the uncertainty on the preferences of the nurses for the working shifts and the weekends off. In fact, a compensatory fuzzy approach based on the Werners’ fuzzy and operator is proposed to investigate the effects of the uncertainty on the considered research problem. Then, several sample problems are generated to support the efficiency of the developed fuzzy model. Finally, a sensitivity analysis is implemented to determine the effects of the changes of the parameters on the obtained results. پرونده مقاله -
دسترسی آزاد مقاله
3 - A bi-objective mathematical model for the patient appointment scheduling problem in outpatient chemotherapy clinics using Fuzzy C-means clustering: A case study
Masoud Rabbani Alireza Khani amirreza Zare niloofar Akbarian-SaraviIn healthcare, the Patient Appointment Scheduling (PAS) problem is one of the critical issues in Outpatient Chemotherapy Clinics (OCC). In the wake of this, this paper proposes a novel bi-objective mathematical programming model for solving the PAS problem in OCC. The d چکیده کاملIn healthcare, the Patient Appointment Scheduling (PAS) problem is one of the critical issues in Outpatient Chemotherapy Clinics (OCC). In the wake of this, this paper proposes a novel bi-objective mathematical programming model for solving the PAS problem in OCC. The developed mathematical model is inspired by cellular manufacturing. The first objective function minimizes the completion time of all treatments, and the second objective function maximizes the use of nurses' skills while considering clustered patients about their characteristics. To solve the bi-objective mathematical model, for the first time a hybrid approach based on Torabi-Hassini (TH) and Lagrange method is utilized. The results indicate that an increase in the number of nurses will enhance the treatment completion speed and allocation of nurses’ work skill. On the other hand, an increase in the number of chairs in clinics will decrease the assignments of nurses’ skills priority. The study supports decision makers in considering nurses' skills for the PAS problem. The results also denote the desirability of the proposed model. To validate the proposed model, OCC in Tehran is considered as a case study. Computational results reveal that considering nurses' skills in OCC and using the fuzzy clustering model, as a new method in patient clustering, lead to achieving a desirable and more realistic outcome. پرونده مقاله -
دسترسی آزاد مقاله
4 - A mathematical programming model for single round-robin tournament problem: A case study of Volleyball Nations League
Hamed Jafari Morteza RajabzadehIn this study, a mathematical programming model is developed for a single round-robin tournament problem to provide a schedule for the preliminary round of the Volleyball Nations League. In this setting, the aim is to assign the teams to the pools at each week as well a چکیده کاملIn this study, a mathematical programming model is developed for a single round-robin tournament problem to provide a schedule for the preliminary round of the Volleyball Nations League. In this setting, the aim is to assign the teams to the pools at each week as well as to specify the host teams of the pools. This schedule is obtained by minimizing the sum of the differences between the total distance traveled by every team and the average of the total distances traveled by all teams. Then, to evaluate the performance of the developed model, it is applied to obtain the optimal schedule for the preliminary round of the Volleyball Men’s Nations League in year 2018. The results indicate that the sum of the travel distance deviations from the average of the total travel distances of all teams obtained from the schedule provided by the mathematical model is significantly lower than that calculated from the schedule presented by the International Volleyball Federation. Moreover, the schedule presented by the International Volleyball Federation leads to a percentage gap of 449.92% in comparison with the optimal schedule provided by the developed model. پرونده مقاله -
دسترسی آزاد مقاله
5 - A stochastic model for operating room planning under uncertainty and equipment capacity constraints
J. Razmi M. Barati M. S. Yousefi J. HeydariIn the present economic context, the operating theater is considered as a critical activity in health care management. This paper describes a model for operating room (OR) planning under constraint of a unique equipment. At first level we schedule elective surgeries چکیده کاملIn the present economic context, the operating theater is considered as a critical activity in health care management. This paper describes a model for operating room (OR) planning under constraint of a unique equipment. At first level we schedule elective surgeries under the uncertainty of using a unique equipment. At the second level we consider emergency surgeries, and at the third level a coefficient factor for surgeons is introduced in using this unique equipment. The planning problem consists in scheduling a unique equipment and assigning elective cases to different periods over a planning horizon to minimize the sum of elective patient related costs and overtime costs of ORs. The most important factor that we have focused on this paper is equipment resource constraint. A new mathematical programming model is first proposed and at the second and third level, a new stochastic mathematical programming model is proposed. Then sample average approximation is presented to approximate the problem with sample size N and then Lingo is used as an exact approach. Because of NP-hardness, exact method does not work for large size problems, so a Metaheuristic approach (differential evolution) is proposed for large size problems. Numerical results show that important gains (approximately 3.5 % in overall cost) can be realized by this stochastic OR planning model. پرونده مقاله
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