ORAHS International Seminar Series

June 23, 2026, 16:00-17:00h (GMT+1): Dr. Miguel Lejeune (George Washington University, USA) - “Emergency Network Design for Opioid Drug Overdoses: Exact Reformulations and Algorithms for Queuing-Based Optimization Models”

Abstract:  In the joint work with Wenbo Ma, we study queueing-based nonconvex optimization models to design networks in which time is of the essence and the objective is to minimize the response time. The problem is motivated and applied for the drone-based delivery of narcan in case of opioid overdoses. The network is modelled as a collection of queueing systems in which the service times and the arrival of requests are random variables whose distribution parameters are determined endogenously. The optimization model takes the form of a nonconvex integer problem with fractional, exponential, and polynomial terms for which we propose (i) a mixed-integer linear programming reformulation framework and (ii) an algorithmic approach involving an outer approximation method and a new family of nested valid inequalities. Numerical tests based on real-data for the city of Virginia Beach will be presented. 

Bio: Miguel Lejeune is a Full Professor of Decision Sciences at the George Washington University. His areas of expertise include stochastic programming, distributionally robust optimization, decision-dependent uncertainty and mixed-integer nonlinear programming. His application areas include health care, wildfire risk, power systems, financial risk, supply chain, disaster management, and military operations. His current research is funded by several grants from the National Science Foundation and the DUKE Energy Innovation Fund. Dr. Lejeune is the recipient of the 2019 Koopman Award of the INFORMS Society, the 2024 Excellence Research Award in Applied Mathematics from the Washington Academy of Science, a CAREER Research Grant from the Army Research Office, and the IBM Smarter Planet Faculty Innovation Award. Dr. Lejeune is a Fellow of the Washington Academy of Science. 

More information about our speaker can be found here: https://business.gwu.edu/miguel-lejeune 

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Recordings of our previous seminar talks are available below.

• May 26th 2026, Dr. David Barrera Ferro, Pontificia Universidad Javeriana, Colombia - Improving fairness in machine learning-enabled affirmative actions: a case study in outreach activities in healthcare. The recording will be available soon.
• April 21st 2026, Dr. Pieter van den Berg, Erasmus University, The Netherlands  - Evaluating and Optimizing the Impact of Community First Responders. The recording of this talk can be found here.
• April 14th 2026, Dr. Jim Duggan, University of Galway, Ireland - A qualitative system dynamics model to support pandemic preparedness. The recording of this talk can be found here.
• February 24th 2026, Prof. Hein Fleuren, Tilburg University, The Netherlands - Fighting Hunger with Analytics: The Zero Hunger Lab Journey. The recording of this talk can be found here.
• January 20th 2026, Dr. Sina Ansari, DePaul University, USA - Optimization Models for Patient and/or Technician Scheduling in Hemodialysis Centers. The recording of this talk can be found here.
• November 25th 2025: Dr. Emilia Grass, Karlsruhe Institute of Technology (KIT), Germany. Cybergeddon in Healthcare: Preparing for the Worst. The recording of this talk can be found here.
• October 28th 2025: Dr. Daniela Guericke and Dr. Matthias Walter, University of Twente, The Netherlands. A hybrid solution approach for the Integrated Healthcare Timetabling Competition 2024. The recording of this talk can be found here.
• September 30th 2025: Dr. Amin Asadi, University of Twente, The Netherlands. Dynamic Recharging and Dispatch Policies in Last-mile Medical Drone Delivery. The recording of this talk can be found here.
• May 27th 2025: Dr. Marta Cildoz and Prof. Fermin Mallor, Public University of Navarre, Spain. Make and impact: Engaging hospital managers to make decisions supported by simulation/digital twin models. The recording of this talk can be found here.
• May 13th 2025: Dr. Anne Zander, University of Twente, The Netherlands. Collaborative Capacity Allocation and Patient Steering: Hospital Planning in a Pandemic. The recording of this talk can be found here.
• April 29th 2025: Prof. Henrik Andersson, NTNU, Norway. Daily Surgical Case Scheduling with Upstream and Downstream Units. The recording of the talk can be found here.
• March 25th 2025: Prof. Christina Büsing, RWTH Aachen, Germany. Fair planning of out-of-hours service for pharmacies. The recording of the talk can be found here.
• February 25th 2025: Prof. Hari Balasubramanian, University of Massachusetts, Amherst, USA. Identifying Associations Between Diseases Using Association Rule Mining and Clustering Methods. The recording of the talk can be found here.
• January 28th 2025: Dr. Harwin de Vries, Rotterdam School of Management, The Netherlands. Enhancing Access to Family Planning Services: Challenges and Opportunities for OR. The recording of the talk can be found here.
• November 26th 2024: Prof. Erik Demeulemeester, KU Leuven, Belgium. How can the partitioning of elective surgeries benefit the inpatient operating theater? The recording of the talk can be found here.
• October 29th 2024: Prof. Peter Vanberkel, Dalhousie University, Canada. Using Machine Learning to Develop Guidelines for Identifying Patients Who May Leave an Emergency Department Without Being Seen. The recording of the talk can be found here.
• September 24th 2024: Prof. Dimitris Bertsimas, Massachusetts Institute of Technology, USA. The R.O.A.D. to precision medicine. The recording of the talk can be found here.
• June 25th 2024: Dr. Derya Demirtas, University of Twente, NL. Unlocking the Value of Extensive Data: Estimating spatial cardiac arrest risk to guide resource allocation decisions. The recording of the talk can be found here.
• May 28th 2024: Prof. Dionne Aleman, University of Toronto, Canada. Pandemic planning from A (agent-based simulation) to V (vaccine prioritization). The recording of the talk can be found here.
• April 30th 2024: Prof. Mónica Oliveira, University of Lisbon, Portugal. Advancing collaborative value modeling in health settings: From applications to novel tools. The recording of the talk can be found here.
• March 19th 2024: Dr. Ana María Anaya-Arenas, Université du Québec à Montréal, Canada. The Biomedical Sample Transportation Problem: routing commodities with very short lifespan.
• February 27th 2024: Prof. Christine Currie, University of Southampton, UK. A Generalisable Digital Twin Simulation Model of an Emergency Department. The recording of the talk can be found here.
• January 30th 2024: Prof. Vedat Verter, Queens University, Canada. Nurse Workload Balancing Using Real-Time Location Data. The recording of the talk can be requested via email.
• November 28th 2023: Dr. Melanie Reuter, University of Twente, NL. SPELL: Supporting emergency services with OR- and AI-based approaches.
• October 17th 2023: Prof. Nadia Lahrichi, Polytechnique Montreal, Canada. Integrating bed use and patient selection to the master surgical planning in the OR. The recording of the talk can be found here.
• September 26th 2023: Prof.Em. Warren Powell, Princeton University, USA. A Universal Framework for Sequential Decision Problems in Health Applications. The recording of the talk can be found here.
• June 27th 2023: Dr. Ana Viana, Polytechnic of Porto, Portugal. Kidney Exchange Programmes: a guided tour from 2004 to 2023. The recording of the talk can be found here, and the corresponding slides here.
• May 30th 2023: Prof. Brian Denton, University of Michigan, MI, USA. Predictive and Prescriptive Models for Early Detection of Prostate Cancer. The recording of the talk can be found here.
• April 25th 2023: Dr. Gréanne Leeftink, University of Twente, NL. Capacity sharing in neonatal care networks. The recording of the talk can be found here.
• March 28th 2023: Prof. Lerzan Örmeci, Koç University, Turkey. Appointment Scheduling with Patient Preferences. The recording of the talk can be found here.
• February 28th 2023: Prof. Jens Brunner, University of Augsburg, Germany. Resident scheduling in teaching hospitals with the use of quantitative methods. The recording of the talk can be found here.
• January 31st 2023: Prof. Retsef Levi, MIT, USA. Analytics Driven Innovation in Health Systems. The recording of the talk can be found here.
• December 6th 2022: Prof. Richard Boucherie, University of Twente, NL. Dynamic assignment of capacity and fair balancing of COVID-19 patients over hospitals. The recording of the talk can be found here.
• November 11th 2022: Prof. Margaret Brandeau, Stanford University, USA. Replacing Complex Models for Health Decision Making with Metamodels: Three Examples. The recording of the talk can be found here.
• October 4th 2022 (joint seminar with WORMS): Prof. Sonya Crowe and Dr. Zella King, University College London, UK. Using OR to make real-time aggregated predictions of hospital admission for emergency patients. The recording of the talk can be found here.
• June 28th 2022: Prof. Paul Harper and Michalis Panayides, Cardiff University, UK. Modelling Healthcare Behaviours: A Game Theoretic Model Between Emergency Departments and Emergency Medical Services Queueing Systems. The recording of the talk can be found here.
• May 31st 2022: Prof. Stefan Nickel, Karlsruhe Institute of Technology, Germany. Health Care Logistics in EMS: A real world case combining Analytics, Simulation and Optimization. The recording of the talk can be found here.

The ORAHS international seminar series is organized by Amin Asadi, Derya Demirtas, Daniela Guericke, Gréanne Leeftink, Janusz Meylahn, and Anne Zander of the CHOIR research center of the University of Twente (The Netherlands). For questions and inquiries feel free to reach out to us via email.

The ORAHS international seminar series is supported by its advisory board, consisting of Richard Boucherie (University of Twente, The Netherlands), and Erwin Hans (University of Twente, the Netherlands), and the ORAHS board.

The ORAHS international seminar series is a EURO Online Seminar Series (EURO OSS), economically supported by EURO.