A mathematical model is developed and tested with plant data for the ammonia cold shot converter of Razi Petrochemical Complex. The model is based on a material and energy balance in a differential element of beds and is subjected to the assumptions of uniform distribution of temperature and composition through a general cross section and negligible mass and heat transfer in axial direction. Th...

in this paper, we develop an inventory model with delay in payments for deteriorating items. in our model, retailer who purchases the items enjoys a fixed credit period offered by his/her supplier and, in turn, also offers a credit period to his/her customers in order to promote the market competition. the demand is assumed to be linear function of the retailer's current-stock level. the effect...

ripening is one of the most important stages in production of cheese. in this research to comprehensive study of uf cheese ripening as the major industrial cheese that is produced in iran, mass transfer, heat transfer and changes in quality and sensory properties, simultaneously considered and a mathematical model was developed to describe them. thus, at first, lipolysis, proteolysis, texture a...

today, due to rising passenger expectations and other resource constraints, the airport managers and staff do to develop appropriate programs in order to optimize the allocation of the resources. gates and counters are important resources in airport. in this research problem of gate and counter for arrival flights is considered simultaneously and mathematical model is prepared. the objectives o...

bus systems are unstable without considering any control. thus, we are able to consider some control strategies to alleviate this problem. a holding control strategy is one commonly used real-time control strategy that can improve service quality. this paper develops a mathematical model for a holding control strategy. the objective of this model is to minimize the total cost related to passeng...

short-selling prohibition has been one of the primary assumptions of markowitz mean-variance model. solving markowitz quadratic model creates investment efficient frontier by considering only two return and budget constraints. in order to develop a more realistic portfolio selection model, in this paper, a new mathematical model is developed to allow short-selling under some practical constrain...

Reliable location routing problem considers a location problem and a vehicle routing problem in order to select the optimal location of facilities and at the same time the optimal routes for vehicles considering the unexpected failure for facilities in which, all facilities may fail with a probability. In this paper, a bi-objective mathematical model has been developed to minimize the total cos...