Webinars

A Branch-Price-and-Cut Algorithm for a Two-Echelon Vehicle Routing Problem with Time Windows

Event Info

icon_calendar.jpgApril 16, 2021
icon_clock.jpg10:00 am ET
icon_stopwatch.jpgDuration: 1 hour  

Speaker

Guy

Guy Desaulniers received his PhD in mathematics from Polytechnique Montreal, where he is a professor in the department of Mathematics and Industrial Engineering. Between 2015 and 2019, he was the director of the GERAD research center. He has supervised more than 65 graduate students, co-authored more than 110 papers published in academic journals, and co-edited a book on column generation. His main research interests are in the areas of large-scale optimization (in particular, column generation), integer programming, combinatorial optimization, and constrained shortest path problems with applications to vehicle routing and crew scheduling in ground, air, rail, and maritime transportation.

 

In this talk, we consider the two-echelon vehicle routing problem with time windows (2E-VRPTW). This problem arises in city logistics when high-capacity and low-capacity vehicles are used to transport merchandise from depots to satellites (first echelon), and from satellites to customers (second echelon), respectively. The aim is to determine a set of least-cost first- and second-echelon routes such that the load on the routes respect the capacity of the vehicles, each second-echelon route is supplied by exactly one first-echelon route, and each customer is visited by exactly one second-echelon route within its time window. We model this 2E-VRPTW with a route-based formulation involving first-echelon and second-echelon route variables. We propose to solve it using a branch-price-and-cut algorithm where only the second-echelon routes are generated by column generation. We discuss some specialized components of this algorithm, namely, the labeling algorithm for solving the pricing problems as well as deep dual optimal inequalities that are added to reduce degeneracy. We report computational results that show that our BPC algorithm outperforms a state-of-the-art algorithm. We also present sensitivity analysis results on the different components of our algorithm, and derive managerial insights related to the structure of the first-echelon routes.

Guy Desaulniers, Polytechnique Montreal and GERAD, Canada

Co-authors: Tayeb Mhamedi, Marilène Cherkesly, Henrik Andersson

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Cobotic Order Picking Systems

Event Info

icon_calendar.jpgMarch 12, 2021
icon_clock.jpg10:00 am ET
icon_stopwatch.jpgDuration: 1 hour  

Speaker

rene

René (M.) B.M. de Koster is a professor of Logistics and Operations Management at Rotterdam School of Management, Erasmus University, and chairs the department Technology and Operations Management. He holds a PhD from Eindhoven University of Technology. He is the 2018 honorary Francqui Professor at Hasselt University. His research interests are warehousing, material handling, and behavioral operations. He is the founder of the Material Handling Forum and is author / editor of 8 books and over 240 papers in books and academic journals. He is associate editor of Transportation Science, Service Science, and Operations Research.

 

The new generation of warehouses will be fully robotized. However, in the nearby future, robots will gradually find their way into the operations and will have to work in close collaboration with manual workers. In my talk, I will discuss two types of cobotic order picking systems, where robots and order pickers work together to fill customer orders: drive-on cobots and walk-along cobots. I will discuss empirical, experiment-based work on the impact on pick performance of robots leading versus robots following the pickers, and analytical modelling research on control strategies and collaboration strategies. Our results show that, with proper deployment, cobots may lead to a substantial increase in picking performance.

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Traffic Management and Control in Fully Automated Vehicle Environment

Event Info

icon_calendar.jpgFebruary 12, 2021
icon_clock.jpg9:30am EST
icon_stopwatch.jpgDuration: 1 hour (plus networking)

Speaker

chang.jpg
Dr. Yafeng Yin is a Professor of Civil and Environmental Engineering and a Professor of Industrial and Operations Engineering at University of Michigan, Ann Arbor. He works in the area of transportation systems analysis and modeling, and has published more than 120 refereed papers in leading academic journals. His current research focuses on connected and automated mobility systems.

In this talk, we present rhythmic traffic control, a new paradigm of controlling vehicles to traverse a traffic facility such as a signal-free intersection and a traffic network, in a fully automated vehicle (AV) environment. The fundamental idea of rhythmic control is to determine an underlying beat for the traffic facility and then require AVs to follow the beat and a design speed to enter and traverse the facility; the start of the beat for each conflicting movement is carefully synchronized so that vehicles will pass through a conflict point in an alternating and collision-free manner without any stop. We show that this new control paradigm is simple, but yields superior performance compared with previous paradigms or proposals, and is computationally tractable and thus scalable.

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On-Demand Multimodal Transit Systems: Capturing Travel Mode Adoption and Assessing Resilience

Event Info

icon_calendar.jpgJanuary 15, 2021
icon_clock.jpg9am EST
icon_stopwatch.jpgDuration: 1 hour

Speaker

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Dr. Pascal Van Hentenryck
H. Milton Stewart School of Industrial and Systems Engineering at the Georgia Institute of Technology

Pascal Van Hentenryck is an A. Russell Chandler III Chair and Professor in the H. Milton Stewart School of Industrial and Systems Engineering at Georgia Tech. Van Hentenryck’s research focuses in Artificial Intelligence, Data Science, and Operations Research. His current focus is to develop methodologies, algorithms, and systems for addressing challenging problems in mobility, energy systems, resilience, and privacy.