Samed Çetinkaya - Academia.edu (original) (raw)

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Papers by Samed Çetinkaya

Journal of Optimization Theory and Applications, 1998

In this paper, we use nonlinear programming to provide an alternative treatment of the economic o... more In this paper, we use nonlinear programming to provide an alternative treatment of the economic order quantity problem with planned backorders. Many businesses, such as capital-goods firms that deal with expensive products and some service industries that cannot store their services, operate with substantial backlogs. In practical problems, it is usually very difficult to estimate accurately the values of the two types of backorder costs, i.e., the time-dependent unit backorder cost and the unit backorder cost. We redefine the original problem without including these backorder costs and construct a nonlinear programming problem with two service measure constraints which may be easier to specify than the backorder costs. We find that, with this different formulation of our new problem, we obtain results which give implicit estimates of the backorder costs. The alternative formulation provides an easier-to-use model and managerially meaningful results. Next, we show that, for a wide range of parameter values, it usually suffices to consider only one type of backorder cost, or equivalently, only one type of service measure constraint. Finally, we develop expressions which bracket the optimal values of the decision variables in a narrow range and provide a simple method for computing the optimal solution. In the most complicated case, this method requires finding the unique root of a polynomial.

Fuel, 1998

The oxidation of polymeric model compounds was investigated and the results are given in this pap... more The oxidation of polymeric model compounds was investigated and the results are given in this paper. Samples were oxidized in air atmosphere at temperatures up to 500°C. A differential scanning calorimetry system (DSC) was used to determine thermo-analytical curves of the polymer compounds. The structure of oxidized polymeric compounds was investigated using FTIR spectroscopy to determine the changes which occur.

Fuel, 1998

The oxidation of polymeric model compounds was investigated and the results are given in this pap... more The oxidation of polymeric model compounds was investigated and the results are given in this paper. Samples were oxidized in air atmosphere at temperatures up to 500°C. A differential scanning calorimetry system (DSC) was used to determine thermo-analytical curves of the polymer compounds. The structure of oxidized polymeric compounds was investigated using FTIR spectroscopy to determine the changes which occur.

Journal of Optimization Theory and Applications, 1998

In this paper, we use nonlinear programming to provide an alternative treatment of the economic o... more In this paper, we use nonlinear programming to provide an alternative treatment of the economic order quantity problem with planned backorders. Many businesses, such as capital-goods firms that deal with expensive products and some service industries that cannot store their services, operate with substantial backlogs. In practical problems, it is usually very difficult to estimate accurately the values of the two types of backorder costs, i.e., the time-dependent unit backorder cost and the unit backorder cost. We redefine the original problem without including these backorder costs and construct a nonlinear programming problem with two service measure constraints which may be easier to specify than the backorder costs. We find that, with this different formulation of our new problem, we obtain results which give implicit estimates of the backorder costs. The alternative formulation provides an easier-to-use model and managerially meaningful results. Next, we show that, for a wide range of parameter values, it usually suffices to consider only one type of backorder cost, or equivalently, only one type of service measure constraint. Finally, we develop expressions which bracket the optimal values of the decision variables in a narrow range and provide a simple method for computing the optimal solution. In the most complicated case, this method requires finding the unique root of a polynomial.

Fuel, 1998

The oxidation of polymeric model compounds was investigated and the results are given in this pap... more The oxidation of polymeric model compounds was investigated and the results are given in this paper. Samples were oxidized in air atmosphere at temperatures up to 500°C. A differential scanning calorimetry system (DSC) was used to determine thermo-analytical curves of the polymer compounds. The structure of oxidized polymeric compounds was investigated using FTIR spectroscopy to determine the changes which occur.

Fuel, 1998

The oxidation of polymeric model compounds was investigated and the results are given in this pap... more The oxidation of polymeric model compounds was investigated and the results are given in this paper. Samples were oxidized in air atmosphere at temperatures up to 500°C. A differential scanning calorimetry system (DSC) was used to determine thermo-analytical curves of the polymer compounds. The structure of oxidized polymeric compounds was investigated using FTIR spectroscopy to determine the changes which occur.