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An inventory model to study the effect of the probabilistic rate of carbon emission on the profit earned by a supplier

Bhattacharjee Nabajyoti, Sen Nabendu

Operations Research and Decisions

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2021

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Vol. 31, No. 4

5--33

EN

Sensitivity analysis of parameters is usually more important than the optimal solution when it comes to linear programming. Nevertheless, in the analysis of traditional sensitivities for a coefficient, a range of changes is found to maintain the optimal solution. These changes can be functional constraints in the coefficients, such as good values or technical coefficients, of the objective function. When real-world problems are highly inaccurate due to limited data and limited information, the method of grey systems is used to perform the needed optimisation. Several algorithms for solving grey linear programming have been developed to entertain involved inaccuracies in the model parameters; these methods are complex and require much computational time. In this paper, the sensitivity of a series of grey linear programming problems is analysed by using the definitions and operators of grey numbers. Also, uncertainties in parameters are preserved in the solutions obtained from the sensitivity analysis. To evaluate the efficiency and importance of the developed method, an applied numerical example is solved.

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An inventory model for deteriorating items with imperfect quality under advance payment policy

Nath Biman Kanti, Sen Nabendu

Operations Research and Decisions

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2021

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Vol. 31, No. 3

109--135

EN

In the business world, it is generally observed that the supplier gives a cash discount due to advance payment. The buyer may either pay off the total purchase cost or a fraction of the total purchase cost before receiving the products. If the buyer makes full payment then he receives a cash discount instantly. If the buyer pays a fraction of the total purchase cost, then (s)he receives the cash discount while paying the remaining amount at the time of receiving the lot. Moreover, in most of the inventory models, it is generally assumed that the delivered lot contains only perfect items. But in reality, the presence of imperfect items in the received lot cannot be overlooked as it will affect the total profit of the system. Thus, the study of inventory models considering the presence of imperfect items in the lot makes the model more realistic and it has received much attention from inventory managers. This paper develops a model that jointly considers imperfect quality items and the concept of an advance payment scheme (full and partial). The objective is to determine optimal ordering quantity to maximise the total profit of the system. The necessary theoretical results showing the existence of global maximum is derived. The model is illustrated with the help of numerical examples, and sensitivity analysis is carried out on some important system parameters to see the effects on the total profit of the system. The study shows that a full advance payment scheme is beneficial for the buyer.

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Inventory model for deteriorating items with negative exponential demand, probabilistic deterioration and fuzzy lead time under partial back logging

Sen Nabendu, Saha Sumit

Operations Research and Decisions

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2020

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Vol. 30, No. 3

97--112

EN

The effect of lead time plays an important role in inventory management. It is also important to study the optimal strategies when the lead time is not precisely known to the decision-makers. This paper aimed to examine the inventory model for deteriorating items with fuzzy lead time, negative exponential demand, and partially backlogged shortages. This model is unique in its nature due to probabilistic deterioration along with fuzzy lead time. The fuzzy lead time was assumed to be triangular, parabolic, trapezoidal numbers. The graded mean integration representation method was used for the defuzzification purpose. Three different types of probability distributions, namely uniform, triangular and beta were used for rate of deterioration to find optimal time and associated total inventory cost. The developed model was validated numerically, and values of optimal time and total inventory cost are given in a tabular form, corresponding to different probability distributions and fuzzy lead-time. The sensitivity analysis was performed on the variation of key parameters to observe its effect on the developed model.