Monthly Archives: November 2013

Congratulations-your-manuscript-has-been-accepted email

It is always fun to get the Congratulations-your-manuscript-has-been-accepted email, but it is especially rewarding when your coauthor of the accepted paper is your Ph.D. student!    This is an academic first for me — an accepted publication with a student.  Congrats to Faraz Ramtin for his hardwork and dedication to this research.  The idea came from me visiting a grocery distribution center and watching their case fulfillment process in cold temperature distribution centers; however, Faraz, took the idea and made it his own.    


The paper specifics:

“Analytical Models for an Automated Storage and Retrieval System with Multiple in-the-Aisle Pick Positions”

Faraz Ramtin 1 & Jennifer A. Pazour 1

1 Department of Industrial Engineering and Management Systems, University of Central Florida, Orlando, FL, 32816, USA


to appear in IIE Transactions.  

An automated storage and retrieval system with multiple in-the-aisle pick positions (MIAPP-AS/RS) is a case-level order-fulfillment technology that enables order picking via multiple pick positions (outputs) located in the aisle. We develop expected travel time models for different operating policies and different physical configurations.  These models can be used to analyze MIAPP-AS/RS throughput performance during peak and non-peak hours. Moreover, closed-form approximations are derived for the case of an infinite number of pick positions, which enable us to derive the optimal shape configuration that minimizes expected travel times.  We compare our expected travel time models with a simulation model of a discrete rack, and the results validate that our models provide good estimates. Finally, we conduct a numerical experiment to illustrate the trade-offs between performance of operating policies and design configurations. We find that MIAPP-AS/RS with a dual picking floor and input point is a robust configuration because a single command operating policy has comparable throughput performance to a dual command operating policy.  




No profession unleashes the spirit of innovation like engineering. From research to real-world applications, engineers constantly discover how to improve our lives by creating bold new solutions that connect science to life in unexpected, forward-thinking ways. Few professions turn so many ideas into so many realities. Few have such a direct and positive effort on people’s everyday lives. We are counting on engineers and their imaginations to help us meet the needs of the 21st century.

New Positioning Statement about Engineering from Changing the Conversation: Messages for Improving Public Understanding of Engineering

Seminar Series at the University of Florida


I presented in the University of Florida’s Industrial and System’s Engineering Seminar Series on Halloween.  I enjoyed my  time among the Gators, especially the time I spent meeting the ISE faculty and learning about the neat research they are working on.  The comments and questions I received from my presentation on “Analytical Modeling of Logistics System Design” sparked some new thoughts and directions for my research.

Here’s my research presentation description:

Logistics is concerned with the efficient flow and storage of goods from point of origin to point of consumption, and plays an important role in our day-to-day lives and our economy.  To illustrate, consider the “journey” of the things we use in our lives.  Think about the succulent strawberries in your lunch that provide nourishment, think about the medical supplies necessary to keeping us healthy, or think about the smart phone that you constantly check.  Logistics has enabled us to enjoy all of these things.  My research focuses on greater understanding of logistic system design through the development of analytical decision-making models.  This presentation will focus on an important problem in distribution center design and in military logistics.

Reshuffling is a warehouse strategy where the storage locations of items are changed during idle time to create a new layout configuration that will improve picking and put-away performance. This study investigates how to optimize reshuffling and quantifies the effect of common assumptions in the reshuffling literature. The contributions of this study include the first mathematical programming formulation for the general reshuffling problem, a lower bound that demonstrates the intrinsic complexity of the problem, several heuristics based on the problem structure, and managerial insights on the performance of reshuffling policies in various environments. Experimental results suggest that the proposed insight-based heuristics statistically improve upon a benchmark heuristic by relaxing how items in cycles are handled and incorporating double-handling.

Seabasing is a strategy implemented by the US Navy that allows Joint Forces to be supported from the sea.  From a logistics perspective, seabasing will transform a set of vessels into floating distribution centers that eliminate the need for a stockpile of materials on shore.  Vital components of seabasing include selective offloading capabilities, ship-to-objective logistics via aerial delivery, and vessel-to-vessel cargo replenishment. Sea-based logistics operate in a challenging and uncertain environment and have unique mission characteristics; consequently, sea-based logistics require the development of specific logistics models.  We are currently building analytical models to help design and evaluate responsive sea-based logistics delivery systems with imperfect visibility.