Monthly Archives: July 2014

Piece Level Order-Fulfillment Technology Selection

IMHRC2014 Pazour and Meller - Piece Level Order Fulfillment Technology Selection


I attended the 2014 International Material Handling Research Colloquium in Mason, Ohio in June.  We had great hosts, Intelligated , which is a company that provides intelligent automated material handling solutions.  This colloquium occurs every 2 years and is one of my favorite venues to present and learn about new research.  The mechanisms used to disseminate research are a Book Chapter and a poster session.  I enjoy the two-way dialog that occurs in a poster session format.

One of my favorite things about Austria is their great public transportation.  I got around Graz with a tram ticket and a bicycle.  It was great.

One of my favorite things about Austria is their great public transportation. I got around Graz with a tram ticket and a bicycle. It was great.

The research I presented was on piece-level order-fulfillment technology selection and conducted with my Ph.D. adviser, Russ Meller, and collaborators at SSI Schaefer and the Technical University of Graz.  The work was sponsored by the National Science Foundation through a Doctoral Dissertation Enhancement Project, which enabled me to live 4 months in Graz, Austria.  Not only did I get to work with engineers who design distribution centers for a living, I got to experience living in another country that has amazing public transportation, fresh bread on every corner, and is the place of musicians like Mozart and Beethoven.

Our research focused on the selection of piece-level order-fulfillment technologies.  To design an effective piece-level order-fulfillment strategy that meets customer requirements while minimizing costs, high-demanded SKUs may be fulfilled differently than low-demanded SKUs.  Consequently, more than one order-fulfillment technology may be required due to the variability in SKU profile.  For example, the Figure below provides an example solution to the Piece-Level Order-Fulfillment Technology Problem.

DemandCurveExampleFor this distribution center and technology characteristics, the top 1800 SKUs are fulfilled using an automated technology (like an A-Frame system) and the bottom 6200 SKUs are fulfilled using a Goods-to-Man technology. The remaining in-between SKUs are fulfilled using manual man-to-goods system.

The goals of our research were two-fold.

  1. First, we were interested in developing a tool that can aid in decision making associated with which  technologies to select and the assignment of SKUs to these technologies.
  2. Second, we wanted to understand what key factors resulted in implementing manual versus automated order-fulfillment technologies and to provide insights into the use of different order-fulfillment technology strategies.

To accomplish these two goals, we developed an Integer Linear Program formulation, validated the methodology with data from industry implementations, and conducted a set of numerical experiments and statistical analysis.

The insight that I found most interesting was that if automation was used for piece-level order-fulfillment it was used for:

  • The few, very fast-moving SKUs
  • The many, slow-moving SKUs.

Implementing automation for your fast-moving SKUs makes sense as the investment cost in automated technologies is justified by the high velocity of these products.  Not so obvious is the reason for automation to pick slow moving SKUS.  The reason occurs due to the large number of slow-moving SKUs and the need for quick order-fulfillment times.

Given that slow moving SKUs make up a large number of the total SKUs (e.g., in e-commerce over 90% of a retailer’s catalog can be comprised of slow-moving SKUs ), a large amount of space is consumed by slow-moving SKUs and if they are picked in a manual system, the order picker will have to travel large distances to retrieve these items.  When customers put demands on delivery times, the order-fulfillment process must be completed quickly.  This means that ALL items must be fulfilled within the allotted time (not just fast-moving items).  Therefore, goods-to-man systems provide cost efficiency and reduced order-fulfillment lead times for slow-moving SKUs by eliminating the significant travel costs in manual systems.

Just to be clear, our analysis found that there are many cases when a manual process is best.  For example, when labor rates or the number of order lines are low, a manual piece-level fulfillment process is often recommended.  If you are interested in details, a pdf version of our book chapter can be downloaded here:

Pazour, Jennifer A. and Meller, Russell D., 2014, “A Framework and Analysis to Inform the Selection of Piece-Level Order-Fulfillment Technologies,” Progress in Material Handling Research: 2014, Material Handling Institute, Charlotte, NC. (Download the PDF )

Awesome students win a bunch of awards

Based on their intellectual curiosity and mad modeling skills, I knew I had some pretty great students working in my research lab.  As validation, they also received a bunch of external recognition in the form of awards, scholarships, and career opportunities.

Graduate Student Researchers

Faraz Ramtin and I

Faraz Ramtin received a Graduate Fellowship and is interning at Hertz Rental Company’s OR department.

Faraz Ramtin was awarded a Graduate Research Excellence Fellowship for the 2014-2015 academic year.  He is also gaining great experiences as an Operations Research Intern at Hertz Rental Company this summer.  Faraz, who proposed his dissertation on analytic models for  a case-level order fulfillment technology, will graduate Spring 2014.  He and I arrived at UCF at the same time and was the first student involved in my research team.  It has been fun to watch him grow in his ability for independent research and analysis.

Ali's Ph.D. Graduation

Ali’s Ph.D. Graduation

Ali Bozorgi graduated this May with his Ph.D.  His dissertation on inventory problems in the cold supply chain was co-advised by Dima Nazzal at Georgia tech and myself.  Ali is off to Clemson as a Post Doctoral Fellow, where I’m looking forward to hearing about his many future successes.




Mohamed did a great job presenting at ISERC

Mohamed did a great job presenting at ISERC

Mohamed Awwad presented his research at the Institute of Industrial Engineers Annual Conference in Montreal to a full house.  It was his first presentation at a research conference and he did a great job describing his work on search and retrieval operations in dense storage systems.  I enjoyed chairing the “family session” that also included other branches of my academic tree: Russ Meller, Tish Pohl, and Pratik Parikh.

Kaveh's send off party watching the Netherlands versus Argentina World Cup Match

Kaveh’s send off party watching the Netherlands versus Argentina World Cup Match. (from left to right: Patrick, Kaveh, Jen, Shahab, and Ali).

Kaveh Azadeh has been awarded an assistantship to pursue his Ph.D. under Rene de Koster in the Department of Technology and Operations Management, Rotterdam School of Management, Erasmus University.  Kaveh and I have worked together on research since we both arrived in Orlando in 2011 and he will definitely be missed in our group, especially for his statistics knowledge and movie recommendations.  As an impromptu send off party, our lab got together to watch the Netherlands vs Argentina game in the World Cup.    Although Kaveh was rooting for his soon-to-be new home country, Messi and Argentina were victorious.

Shahab Mofidi is the newest graduate student addition to our team.  He has been a great asset in solidifying and expanding ideas for my CAREER proposal due next week.  In addition to implementing an optimization and simulation model and getting interesting results with short deadlines, I knew he was a perfect fit for my team when he commented that the font for a figure was different than the main text.  This eye for detail is a must after Russ ruined my ability to look at a document and not see formatting and typo errors :).

 Undergraduate Researchers

I’ve enjoyed exposing undergraduate students to the joys and (maybe some perils) of research.  They have done a great job contributing to our research lab, which isn’t surprising given the awards they’ve racked up.

Huber CSCMP Central Florida Roundtable Scholarship 2014

Chris awarded a scholarship from the CSCMP Central Florida Round Table

Whitney awarded a scholarship from the CSCMP Central Florida Round Table








  • Patrick Reilly was awarded the Outstanding Graduating Senior award from UCF’s Industrial Engineering Department.  As an undergraduate researcher, Patrick did a great job modeling Operations Research problems found in sea-based logistics.  I am very happy that he will stay on as my graduate student and continue working on research that describes mathematically the propagation of uncertainty in dense storage environments.
  • Brandon Finley has been awarded the Institute of Caster & Wheel Manufacturers Honor Scholarship for the 2014/2015 academic term from the Material Handling Education Foundation, Inc.  Brandon and I are working on research on modeling reshuffling policies in warehouses with multiple operators.
  • Whitney Anderson and Chris Huber were both awarded scholarships from the  Council of Supply Chain Management Professionals Central Florida Round Table for the 2014/2015 academic term.  Through the Undergraduate Research Experience provided via EXCEL, both students conducted research in my lab in Spring 2014.  Whitney participated in research on selecting piece-level order-fulfillment technology and Chris participated in analyzing data for sea-based logistics policies.
  • Margot Tejera was awarded the 2014/2015 UPS Scholarship for Minority Students, which is a National IIE Scholarship awarded to one undergraduate IE student each year.  Margot was a former undergraduate researcher in my lab and she is the current student president of the IIE student chapter.
  • I have been fortunate to have Mohmoud Sbeih and Kristin Elias’s help in writing my CAREER proposal this summer.  Both undergraduate students have provided valuable insights to the research and educational objectives of the proposal.  I’m excited that both will continue research in my lab and are currently in the process of defining a project that they can individually take the lead on.