An M/G/1 retrial queue with two-phase service and feedback is studied in this paper, where the server is subject to starting failures and breakdowns during service. Primary customers get in the system according to a Poisson process, and they will receive service immediately if the server is available upon arrival. Otherwise, they will enter a retrial orbit and are queued in the orbit in accorda...

An extended economic production quantity (EPQ) model under stochastic demand is investigated in this paper, where a fixed lot sizing policy is implemented to reduce the complexity of production planning and inventory control, and outsourcing with a secondary facility is used to supplement the lot sizing policy and to cope with the random demand. The considered cost includes: setup cost for the ...

This paper deals with an economic production quantity (EPQ)model for deteriorating items with price and advertisement dependent demand. We have considered three types of continuous probabilistic deterioration functions to determine the total inventory cost. Here, the rate of replenishment is considered to be a variable and the generalized unit production cost function is formulated by incorpora...

Supply chain management is concerned with the coordination of material and information flows in multi-stage production systems. Inventory management has long been treated as an isolated function solely focused on individual entities, taking into account concerned with single-vendor-single-buyer and single-vendormultiple-buyer-models. Concerning the supplier selection problem, quantitative model...

We consider a single-item, periodic-review inventory model with uncertain demands in which each period's production volume is limited by a capacity level. The demand distributions, capacity levels, and cost parameters vary according to a periodic pattern. We prove that modified base-stock policies are optimal for the finite-horizon planning model and for both the infinite-horizon discounted and...

we propose to use a mathematical method based on stochastic comparisons of markov chains in order to derive performance indice bounds‎. ‎the main goal of this paper is to investigate various monotonicity properties of a single server retrial queue with first-come-first-served (fcfs) orbit and general retrial times using the stochastic ordering techniques‎.

This study aims to select optimal maintenance strategy for components of an electric motor of the National Iranian Oil Refining and Distribution Company. In this regard, a method based on revised multi choice goal programming and analytic hierarchy process (AHP) is presented. Since improving the equipment reliability is an important issue, reliability centered maintenance (RCM) strategies are i...

A production inventory model is formulated for a single item. Here,demand varies with the on-hand inventory level and production price. Shortages are allowed and fully backlogged. The time gap between the decision and actual commencement of production is termed as ’preparation time’ and is assumed to be crisp/imprecise in nature. The set-up cost depends on preparation time. The fuzzy preparatio...

In this paper, a fuzzy production inventory model with resalable returns has been analysed in an imprecise and uncertain environment by considering the cost and revenue parameters as trapezoidal fuzzy numbers. The main objective is to determine the optimal fuzzy production lotsize which maximizes the expected profit where the products leftout at the end of the period are salvaged and demands wh...