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Dipayan Banerjee and Sushil Varma, Ph.D. students in Operations Research at the H. Milton Stewart School of Industrial and Systems Engineering (ISyE), were recently selected as finalists for the INFORMS Transportation Science and Logistics (TSL) student paper competition. The winner will receive the TSL Best Student Paper Award, given to an outstanding paper primarily authored by a student(s) and whose topic is of interest to the broad TSL community.

Out of a total of 40 submissions, four were designated as finalists. The winner will be chosen at the October 15-18, 2023 INFORMS Annual Meeting taking place in Phoenix Arizona, during which the finalists will showcase their work in a dedicated session. All finalists receive a commemorative plaque, and the winning entrant(s) receives a $500 honorarium. In addition, the winning paper, if not published or under review elsewhere, will be invited for a fast-track review at Transportation Science.

Dipayan Banerjee
Fleet Sizing and Service Region Partitioning for Same-Day Delivery Systems

Many existing Same-Day Delivery (SDD) studies focus primarily on operational dispatch problems and do not consider system design questions. Furthermore, prior work on SDD system design does not consider the fleet sizing decision when a service region may be partitioned into zones dedicated to individual vehicles (such designs have been shown to improve system efficiency in related vehicle routing settings). Banerjee's research utilizes a novel approach to addressing two key tactical design challenges when planning an SDD system: figuring out how many delivery vehicles you need and dividing the delivery area into manageable zones.

Using continuous approximations to capture average-case operational behavior, the problem of independently maximizing the area of a single-vehicle delivery zone is considered first. The approach then characterizes area-maximizing dispatching policies and leverages the results to develop a procedure for calculating optimal areas as a function of a zone's distance from the depot, given a maximum number of daily dispatches per vehicle. Using minimal computation, the approach specifies fleet sizes and builds vehicle delivery zones that meet operational requirements, verified by simulation results.

Sushil Varma
Electric Vehicle Fleet and Charging Infrastructure Planning

Varma's research focuses on finding the best way to dispatch electric vehicles to pick up customers while making sure they charge periodically. As customer requests arrive, system operators must determine the minimum number of vehicles and chargers for a given service level, along with a matching and charging policy that maximizes that service level. Varma's approach provides a sharp characterization of the fleet size and the charging infrastructure requirements as demand grows. The research highlights the fundamental differences between planning for an electric vehicle system and a gas-powered system. To understand the difference, note that serving a customer comprises two steps -  pickup and trip, each contributing to the fleet size requirement of the system. As EVs require charging time, they need more vehicles to compensate for the trip part of the service. In turn, the optimal dispatching policy can reduce the EV requirement induced by the pick up part of the service by lowering the pickup times, owing to the extra EVs due to the trip phase. The reduction in the EV requirement depends on the number of charging stations and the size of the EV battery packs. 

The research proposes the "Power-of-d" dispatching policy, which achieves this performance by selecting the d closest vehicles to a trip request and choosing the one with the highest battery level. Varma also conducted detailed simulations that verified the scaling results. The paper discusses how the results extend to accommodate demand that increases/decreases repetitively or cyclically over time.

About Dipayan

Dipayan Banerjee is a fifth-year ISyE Ph.D. candidate advised by Professors Alan Erera and Alejandro Toriello. He is broadly interested in optimization for logistics and supply chain management with a focus on modern e-commerce systems. His doctoral research, supported by the NSF Graduate Research Fellowship and the Eisenhower Transportation Research Fellowship, studies demand management and delivery optimization for e-retail fulfillment. Dipayan was jointly awarded ISyE's Atlanta Air Cargo Association Fellowship for Ph.D. Research Excellence in Supply Chain Engineering in 2022. In addition to being named a finalist for the 2023 INFORMS TSL Society Best Student Paper Award, he also was a finalist for the 2019 INFORMS Undergraduate Operations Research Prize.

About Sushil

Sushil Varma, also a 5th-year ISyE Ph.D. student, is advised by Professor Siva Theja Maguluri. His research interests include queueing theory, game theory, and revenue management with applications in electric vehicles, online marketplaces like ride-hailing, load balancing, and stochastic processing/matching networks. Sushil was awarded the Stephen. S. Lavenberg Best Student Paper Award in IFIP Performance 2021 and the Alice and John Jarvis Best Student Paper Award in 2022.

We extend our wishes for success to both of these remarkable students. Their dedication, hard work, and commitment to their research have already set them on a remarkable path. Regardless of the outcome, their recognition is a testament to academic excellence.