This paper proposes a fuzzy multi-objective integer linear programming approach to model a material requirement planning (MRP) problem with fuzzy lead times. We incorporate to the crisp MRP model the possibility of occurrence of each one of the possible lead times. Then, an objective function that maximizes the possibility of occurrence of the lead times is considered. By combining this objecti...

A firm receives orders that will be required at an uncertain time given by an Erlang distribution, and over time observes the associated independent exponential events. The firm, in turn, places orders at a linear cost from a supplier with fixed lead time l and has the option of converting (expediting) each order, at a cost, over a certain time interval after the order is originally placed. A c...

This paper explores qualitative effects of lead-time uncertainty in a basic continuous-time single-item inventory model with Poisson demand and stochastic lead times. The objective is to minimize the infinite-horizon expected total discounted cost. Order costs are linear, so a base-stock policy is optimal. Traditionally and intuitively, people believe that a (stochastically) longer lead time re...

This study considers a two-echelon supply chain (SC) consisting of single vendor and buyer by reducing delivery time. paper examines time optimization as an essential component lead times. The length production are studied simultaneously. decision variable is considered in the proposed model. Reducing vital incentive factor encouraging to participate coordinated model guarantee profitability. A...

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 paper considers certain comparison techniques involving Markov chains with transition matrices Pa = aI+(1?a)P where P is the transition matrix of a doubly stochastic Markov chain. This paper provides upper bounds for how far the Markov chain with transition matrix Pb is from uniformly distributed after n steps. These upper bounds involve how far the Markov chain with transition matrix Pa i...

In this paper we extend the generalized surrogate optimization approaches and the stochastic comparison so as to tackle the lot-sizing problem in manufacturing system. In practice, with the surrogate methodology, the lot sizes are continuously adjusted on-line by the gradient-based approaches. The lot sizing determines the number of parts batched together for production. We utilize the queueing...

Motivated by many industrial applications, we study a basic discrete-time model of reserving capacity (equivalently, quoting lead times) in a make-to-order setting for customers belonging to two diierent classes. Demands in each period are stochastic. Diierent customer classes penalize us with diierent margins for the lead times quoted to them. We derive the optimal policy for reserving capacit...

This research addressed the Bullwhip Effect (BWE) in the supply chain of small companies and quantified the impact of the interaction between demand management strategies and forecasting methods on BWE. Experiments were performed with four management strategies and three forecasting techniques for different levels of seasonality, lead times, and order batching. Results indicate that no demand m...