Prof. Barrett Thomas, Associate professor, Department of Management Sciences, University of Iowa, USA. Minimizing Time-Dependent Emissions and Total Cost Routing in Urban Areas (May 05, 2016, 15:30-16:30, Thursday) Room 412, Shunde Building 2016.04.13

【Title】 Minimizing Time-Dependent Emissions and Total Cost Routing in Urban Areas


【Presenter】Prof. Barrett Thomas, Associate professor, Department of Management Sciences, University of Iowa, USA


【Host】 Dr. Lei Zhao


【Date】 May 05, 2016, 15:30-16:30 (Thursday)


【Venue】Room N412, Shunde Building




【Abstract】This paper focuses on the problem of minimizing time-dependent emissions and total cost in the routing of vehicles in urban areas.  Historically, routing problems have focused on the minimization of time or distance.  More recently, many authors have begun exploring the minimization of emissions and total cost and have realized the importance of speed in minimizing these objectives.  In fact, most of the existing literature assumes that vehicles can travel at the emissions- or cost-minimizing speed on each arc in the road network. However, in urban areas, vehicles must travel at the speed of traffic, which is variable and time-dependent.  Because of the nonlinearity of fuel consumption curves, optimizing emissions and total cost in an urban areas require explicit consideration of this variability. Further, the best routes also depend on the vehicle load. Because of the dependence on load, we must simultaneously solve the shortest path problem between customers when determining the optimal routes.  This necessity can add significant computational challenges to the optimization.  We introduce a result that identifies when the emissions- or cost-minimizing path between customers is the same for all loads and can then be precomputed.  To solve the shortest path problems, we propose two methods for finding expected emissions-minimized and total cost-minnimized paths between pairs of nodes. One method is based on an adaptation of deterministic shortest path algorithms, while the other involves sampling.  To solve the routing problem, we adapt an existing tabu search algorithm. We test our approach on instances from a real road network dataset and 230 million speed observations.  Experiments with different numbers of vehicles, vehicle weights, and pickup quantities demonstrate the value of our approach.


【Bio】Barrett Thomas is an Associate Professor and a Gary C. Fethke Faculty Research Fellow in the Department of Management Sciences at the Tippie College of Business of the University of Iowa in Iowa City, Iowa.  Professor Thomas’ research focuses stochastic sequential decision making with applications primarily in stochastic and dynamic vehicle routing and in workforce planning.  His work has appeared in journals such as Operations Research, Transportation Science, INFORMS Journal on Computing, and the European Journal of Operational Research.  His research has been sponsored by the United States National Science Foundation as well as private industry.  Professor Thomas also serves as an associate editor for Transportation Science, IIE Transactions, Surveys in Operations Research and Management Science, and INFOR.  Professor Thomas currently serves as the Past President of the INFORMS Transportation Science and Logistics Society having served as the Society’s President in 2015.  In 2011 and 2012, Professor Thomas served as an INFORMS Board member in the role of Vice President Sections/Societies.  In this capacity, he chaired the INFORMS Sections/Societies Committee and Subdivisions Council.  INFORMS is the world’s largest professional society devoted to analytics and operations research professionals.  Professor Thomas is also a Trustee of Grinnell College and has served as the Vice Chair of the Board in 2014 and 2015 and is now the Chair of the Board’s Trustee & Trustee Organization Committee.


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