Productivity optimization using fractional programming in Esfordi phosphhate complex

Productivity is one of the most critical factors affecting the competitiveness of firms. The measurement of productivity is a tool for the management of inputs utilization to obtain favorite outputs. Fractional programming is one of the popular methods in optimization and can be used to maximize a ratio of physical or economic functions، such as، volume/time or revenue/cost in order to measure the efficiency or productivity of the firms. In this paper، a fractional programming model is presented to optimize the productivity considering the associated constraints. The model is utilized to measure and improve productivity of the Esfordi phosphate complex in Yazd province، which is the only phosphate mine in Iran. The data is related to the years 2006 -2009. The objective function is the ratio of revenue to variable operating costs. The proposed model includes 576 variables and 626 linear constraints. The results obtained by solving the model showed that the firm productivity can be improved up to 9 percent