The fill rate is usually computed by using the traditional approach, which calculates it as the complement of the quotient between the expected unfulfilled demand and the expected demand per replenishment cycle, instead of directly the expected fraction of fulfilled demand. Furthermore the available methods to estimate the fill rate apply only under specific demand conditions. This paper shows ...

In this paper, an economic production quantity (EPQ) inventory model with interruption in process, scrap and rework is developed and analyzed. The inventory model is for multiple products and all products are manufactured in a unique machine. Obviously, the existence of only one machine results in limited production capacity and shortages. Therefore, shortages are permitted and fully backordere...

A significant extension of the classic EOQ model is the assumption that realized demand decreases if customers are forced to backorder. To capture the way this decrease depends on the waiting time, different functional forms have been proposed, ranging from the simple (e.g., constant or linear forms) to the complex (e.g., exponential or rational forms.) This paper explores the question of wheth...

In this paper, we consider stock rationing problem of a single-item make-to-stock production/inventory system with multiple demand classes. Demand arrives as a Poisson process with a randomly distributed batch size. It is assumed that the batch demand can be partially satisfied. The facility can produce a batch up to a certain capacity at the same time. Production time follows an exponential di...

One of the most fruitful areas in the line of inventory is that the deficiency of handling/ production facilities can be overcome through a natural phenomenon known as learning effect. Due to this the performance of service and manufacturing organizations engaged in a repetitive process improves with time. The proposed economic order quantity model (EOQ) in this paper has been made realistic by...

In this paper, we apply continuous review (S-1, S) policy for inventory control in a three-echelon supply chain (SC) including r identical retailers, a central warehouse with limited storage space, and two independent manufacturing plants which offer two kinds of product to the customer. The warehouse of the model follows (M/M/1) queue model where customer demands follow a Poisson probabilit...

We consider a joint inventory-pricing problem in which buyers act strategically and bid for units of a firm’s product over an infinite horizon. The number of bidders in each period, as well as the individual bidders’ valuations, are random but stationary over time. There is a holding cost for inventory and a unit cost for ordering more stock from an outside supplier. Backordering is not allowed...

We introduce a class of models, called newsvendor networks, that allow for multiple products and multiple processing and storage points and investigate how their single-period properties extend to dynamic settings. Such models provide a parsimonious framework to study various problems of stochastic capacity investment and inventory procurement. Newsvendor networks can feature commonality, ßexib...

To control a production-inventory system, a manager has to consider the variability in demand as well as variability in her production process. Both types of variability corrupt system performance and by alleviating either of them, the manager can improve the performance of the system. There has been a recent trend towards investing in better information systems to provide better advance demand...

Department at the University of Arkansas. He has published over 65 journal and refereed conference articles in the areas of transportation, manufacturing, health care and simulation and has obtained over $3.1 million dollars in research funding. His research interests include the design, analysis, simulation, and optimization of inventory and logistics systems. He serves as an Associate Editor ...