Category Archives: Logistics

IIE Transactions Best Paper Honorable Mention

 

ISERC 2016 Repositioning Rental Vehicles Presentation

My co-authors and I received an honorable mention designation in the IIE Transactions Focused Issue on Design and Manufacturing Best Applications Paper Award Competition for 2016. (The award is selected by an examining committee from all papers published from July 1, 2014 through June 30, 2015, issues 46:7 through 47:6).

Roy, Debjit, Jennifer A. Pazour, and René De Koster. “A novel approach for designing rental vehicle repositioning strategies.” IIE Transactions 46.9 (2014): 948-967.

While the paper can be downloaded here  I also had the opportunity to present our research at the Industrial and Systems Engineering Research Conference.  If you weren’t able to attend my talk, here’s the cliff notes version.

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The rental car industry has experienced “the Amazon effect” where customers place requests with little or no warning.

ResearchFocus

An important tactical decision for vehicle rental providers is the design of a repositioning strategy to balance vehicle utilization with customer wait times due to vehicle unavailabilities.

 

RentalOptions

To address this problem, this article analyzes alternative repositioning strategies: a no-repositioning strategy, a customer repositioning strategy, and a vehicle repositioning strategy, using queuing network models that are able to handle stochastic demand and vehicle unavailabilities.

ResearchGoal

Optimization models are formulated to determine the repositioning fractions for alternate strategies that minimize the rental provider’s cost by balancing repositioning costs with customer waiting penalty costs. The nonlinear optimization problems are challenging to solve because the objective functions are non-differentiable and the decision variables (such as effective arrival rates and customer repositioning fractions) are interrelated.

CostFunctions

Therefore, a two-phase sequential solution approach to estimate the repositioning fractions is developed. Phase 1 determines the effective arrival rates by developing an approximate network model, deriving structural results, determining a high-quality solution point, and refining the solution. Phase 2 determines the repositioning fractions by solving a transportation problem.

SolutionApproach

Numerical experiments are used to evaluate the efficacy of the proposed solution approach, to analyze alternate repositioning strategies, and to illustrate how the developed techniques can be adopted to create a better readiness at a depot.

CurrentState

OrlandoExample

Conclusions

Outlook 2016

WERC2016OutlookFrontPage

As one of five industry thought leaders, I share my observations and insights on potential critical issues likely to impact the warehouse/DC sector this year in the January/February 2016 issue of the WERC Sheet.

Contributors to WERCSheet’s Outlook 2016 panel include: Steve Johnson, managing principal, Johnson Stephens Consulting; Jennifer Pazour, Ph.D., assistant professor of industrial and systems engineering, Rensselaer Polytechnic Institute; Norman Saenz, managing director, St. Onge Company; Geoff Milsom, director, enVista; and Lawrence Dean Shemesh, president-CEO, OPSdesign Consulting.

My Outlook for 2016 is provided below:

The millennial generation
Jennifer Pazour, Ph.D.

The millennial generation has a major stake in defining both what the warehouse industry needs to do, as well as who will help get it done.  Specifically, the millennial generation is the warehouse industry’s current and future customers, as well as its workforce.

From a customer perspective, millennials are eager to do everything on their smart phones, and have very little patience for non-valued added activities, such as waiting.  This has implications for the warehousing industry as it changes order profile structures and lead time expectations.  Thus, distribution and logistics operations will need to be designed to be agile and responsive.

The millennial workforce, who are interested in making an impact, skilled in technology, and natural at identifying non-valued added processes, seem like a great solution to meet such dynamic customer demands.

For a warehouse to be responsive to dynamic customer demands, as well as profitable, utilization of both physical and human resources is a high priority.  An emerging way to achieve effective resource utilization in a dynamic environment is through the use of on-demand peer-to-peer logistics systems.

These systems use a business model for the movement and storage of goods that matches resources owned by a group of independent users to demand requests.  These systems are part of the “sharing economy” and utilize technology platforms that are able to provide wide reach visibility into untapped resource capacity (such as warehouse space, transport space, and delivery services).

A variety of such companies have sprung up in all aspects of the supply chain.  These include companies like FLEXE that connects companies with underutilized warehousing capacity to companies that need space, as well as companies that facilitate crowdsourced transport and delivery, like Deliv, Instacart, Amazon Flex, and Cargomatic.

On-demand peer-to-peer logistics systems have the ability to improve resource efficiency by increasing visibility and accessibility of existing, idle resource capacities.  They can reduce the costs associated with changing resource capacity, which allows companies to be more flexible.

In addition, these system, which require supply chain visibility and security, will also influence traditional warehousing and logistics operations.   Initiatives that improve supply chain visibility, create increased transparency and security, and embrace technology, will create new capabilities and business opportunities for traditional warehousing and logistics operations as well.

As an industry, we should position ourselves as proactively leading the charge to provide increased customer service capabilities by embracing new business models, technologies, and the changing workforce.

I’m excited to continue this discussion while I moderate a panel on “Crowdsourcing and Collaborative Warehousing and Logistics” at the 2016 Warehousing and Education Research Council Conference in Providence, RI in May.  To check out the conference preview and read the other through leaders’ thoughts on 2016, check out the WERC website.

Successful Defenses

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Congrats to Dr. Faraz Ramtin, who successfully defended his Ph.D. dissertation thesis entitled, “Modeling and Analysis of Automated Storage and Retrieval Systems with Multiple in-the-aisle Pick Positions,” and to Patrick Reilly, who successfully defended his M.S. thesis entitle, “Propagation of Unit Location Uncertainty in Dense Storage Environments.”

I am super proud of both students, who are excellent researchers and human beings.

 

 

Faraz’s dissertation consists of three contributions all focusing on a special type of case-level order fulfillment technology – an “Automated Storage and Retrieval System with Multiple in-the-aisle pick positions.” These semi-automated systems are common in temperature-controlled warehouses.  Our first contribution includes the first study to analyze AS/RS with multiple in-the-aisle outputs. We develop expected travel time models for random storage policies and provide design insights into these systems.  In our second contribution, we considered the use of MIAPP-AS/RS to fulfill orders for non-identical items’ demand, which relaxed some of the assumptions we made in the first contribution. Specifically, we focused on an important practical design decision, the optimal SKU assignment problem. We studied the impact of different pick position assignments on system throughput, as well as system design trade-offs that occur when the system is running under different operating policies and different demand profiles. We developed optimization models to find the optimal assignment that minimizes the expected travel time.  Finally, we developed optimization models for the SKU-to-pick position assignment problem for dedicated and class-based storage policy for MIAPP-AS/RS.  By exploiting the structure of these optimization models, we decomposes the problem using Benders decomposition.

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The first two contributions of Faraz’s dissertation work has been accepted for publication:

  • Ramtin F., Pazour J. A. “Analytical Models for an Automated Storage and Retrieval System with Multiple in-the-Aisle Pick Positions”. IIE Transactions, 46(9), 968-986.
  • Ramtin F., Pazour J. A. “Product Allocation Problem for an AS/RS with Multiple in-the-Aisle Pick Positions”. IIE Transactions, Accepted Manuscript.

He is working on the manuscript of his third contribution, which explores a dedicated storage policy in these systems.

Patrick’s work focuses on dense storage environments and adds an additional dimension to the warehousing literature in that area, specifically item location uncertainty.  Effective space utilization is an important consideration in logistics systems and is especially important in dense storage environments. Dense storage systems provide high-space utilization; however, because not all items are immediately accessible, storage and retrieval operations often require shifting of other stored items in order to access the desired item, which results in item location uncertainty when asset tracking is insufficient. Given an initial certainty in item location, we use Markovian principles to quantify the growth of uncertainty as a function of retrieval requests and discover that the steady state probability distribution for any communicating class of storage locations approaches uniform. Using this result, an expected search time model is developed and applied to the systems analyzed. We also develop metrics that quantify and characterize uncertainty in item location to aid in understanding the nature of that uncertainty. By incorporating uncertainty into our logistics model and conducting numerical experiments, we gain valuable insights into the uncertainty problem such as the benefit of multiple item copies in reducing expected search time and the varied response to different retrieval policies in otherwise identical systems.IMG_1745

Material Handling Education Foundation Scholarships

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I’m honored to be featured in the Where are they now? article in the MHI Solutions Magazine.  [PDF] You have to read through to the bottom to find my favorite quote from the article, which is

“I find the work extremely rewarding,” Pazour said.  “One of the aspects that I really like about my job is that I get paid to learn.  I’m both creating knowledge and disseminating knowledge to my students, and that’s very rewarding.”

I’m even more excited to announce that two of the students in my research group are recipients of a 2015/2016 Material Handling Education Foundation Scholarship.  The Material Handling Education Foundation provides scholarships and educational opportunities to students studying in the field of material handling, logistics and supply chain.

  •  Shahab Mofidi was awarded the Lee Wood Scholarship for the 2015/2016 academic year from the Material Handling Education Foundation, Inc.
  • Catherine Ninah was awarded the Crane Manufacturers Association of America Honor Scholarship for the 2015/2016 academic year from the Material Handling Education Foundation, Inc.

Shahab Mofidi is a Ph.D. student in the IEMS department, and his research focuses on logistical decision making in environments that exhibit item location uncertainty.  Some examples include sea-based logistics, as well as ship-from-store fulfillment operations for e-commerce orders.  Catherine Ninah is an undergraduate student in the IEMS department, who has conducted research on sea-based logistics and healthcare logistics.  In addition, Catherine will participate in an REU (research experience for undergraduates) this summer at Duke University.  She’ll be working with The Center for the Environmental Implications of NanoTechnology (CEINT) on Risk Assessment and Modeling.

MHEF

 

Catherine Research Poster

What Supply Chain Means to Me? #SC4ME

SupplyChainDay

April 10th, 2014 is Supply Chain Day.  And to celebrate, Eye for Transport is posting a daily quote on what supply chain means to individuals within the industry.  Given my primary research focus is applying operations research methodologies to logistic challenges, I thought I would offer my opinion on what supply chain means to me.

Supply chain and logistics enables us to experience the things that make us happy and healthy.  Here are three personal, tangible reasons why I think supply chain and logistics play an important role in our day-to-day lives and our economy.

  1. FacebookLogistics
    The picture above is a screen shot of my mother-in-law’s Facebook post around her birthday.  Logistics is THE modern marvel that enables her to enjoy beautiful tulips in frigid Wyoming in February.

  2. PazourFamilyFeedersMy family is in the beef business.  They produce a great product that they believe should be consumed around the world.  Great supply chains and logistics are what enable me to enjoy Pazour Beef in Florida.  On the flipside, logistics is also what enables my Dad to enjoy Lobster in South Dakota.  Without logistics, we would be confined to experiencing only the products that we could produce in front of us.
  3. Given that in the U.S. almost 40 percent of the drugs we take are made somewhere else, logistics plays a vital role in getting the medications that save lives to the patients that need them. 

To understand what supply chains have done for others, follow the twitter hashtag #SC4ME.

In Good Company

MHILogo

Today I stumbled upon the following press release announcing the winners of the 2013 Material Handling Institutes’ Material Handling and Logistics Research Grants.  Hector Vergara and I are recipients of the Start Up Grant.  Dean Jensen and Adam Piper are recipients of a Spark Grant.  I am honored to be in such good company, especially because I was an undergraduate student in Dean’s statistical quality control course at South Dakota School of Mines & Technology and went to graduate school at the University of Arkansas with Hector.  What a Small World!

One of the joys of an academic career is the many “excuses” to see old friends at conferences (as well as the chance to meet new ones).  I am excited that I will get to reconnect with Hector and Dean at the 2014 International Material Handling Research Colloquium (IMHRC) in Ohio this summer.

A Random Aside:

Based on Ugander,  et al. and Backstrom et al. , I guess it really is a small world — any two people are separated by only four degrees of friendship on average.

Four Degrees of Separation

The Exciting World of Logistics

There has been a lot of buzz about logistics lately — more specifically, the future of logistics.  Two big stories from two big tech companies hit this week.

amazon-delivery-drone

The first is about Amazon testing a drone delivery system they call “Prime Air” for last-mile delivery.  The technology is still under development and has some regulation hurdles to overcome, but it is a solution to a difficult logistics feat — same hour delivery.  The idea of being able to order something one minute and a half hour later being able to enjoy that something is pretty exciting.  Of course this service wouldn’t be for all items or all customers — instead it would be focused on delivering products less than 5 pounds in urban areas in close proximity of distribution centers.  But, that would still cover my household and we order everything from Amazon.  I really mean everything: in the last month alone, we have had cases of soup, cases of cereal bars, a bobble-head doll of Walter White, toothbrush heads, hair gel, numerous CD’s, a few video games, a handful of books, printer toner, plus other essential items delivered to our door.  Just think what we would order if it would arrive in a half hour!

The second story comes from Google — who has been acquiring companies with a focus on automation and many of the applications are in supply chain and logistics.  The recent New York Times article, “Google Puts Money on Robots, Using the Man Behind Android” makes me think that Google thinks logistics is an exciting field with lots of opportunities — I do too!

Some quotes from the article:

“A realistic case, according to several specialists, would be automating portions of an existing supply chain that stretches from a factory floor to the companies that ship and deliver goods to a consumer’s doorstep.”

“The opportunity is massive,” said Andrew McAfee, a principal research scientist at the M.I.T. Center for Digital Business. “There are still people who walk around in factories and pick things up in distribution centers and work in the back rooms of grocery stores.”

Logistics is pretty cool, huh!