Homepage        CV        Research        Contact


RESEARCH

My broad area of interest is operations research/optimization, particularly focused on integer programming, combinatorial optimization and robust optimization, and their applications. You can check my Google Scholar Profile, ORCID Profile, or Publons Profile.  

During my PhD (and since then), I worked on challenging lot-sizing/production planning problems - these problems are attractive as they can realistically represent the real-world production systems and they are difficult to solve - this is the fun part!  See details/download here MULTILSB, the benchmark test set of 120 lot-sizing instances, already used by many other researchers (also see my very first paper below) - these are multi-item, multi-level problems with backlogging.  Three of the hardest instances were also selected for inclusion in MIPLIB 2010.

Since then, I have been working on a number of different mixed integer programming (MIP) and robust optimization applications, in particular large-scale transportation problems (airline scheduling and offshore windfarm installation logistics), staff scheduling/routing (vessel crew, home carers, and nurses), and radiation treatment planning, among others.  For VMAT, we have generated a test set for radiation treatment planning using Volumetric-Modulated Arc Therapy (VMAT), please click here to access this set at my colleague Vicky's page.

Below you can find my publications (including pre- or post-prints for almost all unless prohibited by publishers) and technical reports to download, as well as links to final publications.  If any links do not work appropriately, please let me know. If you want a copy of any of these papers (including those I could not post a pre- or post-print version), please email me and I'll happily send it to you.  Updates on my research will be announced here as soon as possible.

Publications in Refereed Journals and Selected Refereed Proceedings (in reverse chronological order):

32. "Economic Lot-Sizing Problem with Remanufacturing Option: Complexity and Algorithms", with Ashwin Arulselvan and Wilco van den Heuvel, Forthcoming in Optimization Letters, 2021     Postprint     The final publication is available as Open Access here: doi:10.1007/s11590-021-01768-3

31. "A Heuristic Approach for the Distance-Based Critical Node Detection Problem in Complex Networks", with Glory Alozie, Ashwin Arulselvan, and Eduardo Pasiliao, Forthcoming in Journal of the Operational Research Society, 2021.     Postprint      The final publication is available here: doi:10.1080/01605682.2021.1913078

30. "Efficient Methods for Distance-Based Critical Node Detection Problem in Complex Networks", with Glory Alozie, Ashwin Arulselvan, and Eduardo Pasiliao, Computers & Operations Research, 131:105254, 2021.     Postprint      The final publication is available here: doi:10.1016/j.cor.2021.105254

29. "Decomposition Based Heuristics for a Lot Sizing and Scheduling Problem on Multiple Heterogeneous Production Lines with Perishable Products", with Willy A.O. Soler and Maristela O. Santos, Pesquisa Operacional, 2021.      The final publication is available here as Open Access: doi:10.1590/0101-7438.2021.041s1.00240377

28. "Foreword: Special Issue on Recent Advances in Lot Sizing", with Maristela O. Santos, Raf Jans and Silvio A. de Araujo, Pesquisa Operacional 41, 2021.      The final publication is available here as Open Access: doi:10.1590/0101-7438.2021.041s1.0041s101

27. "A Multistage Optimisation Algorithm for the Large Vehicle Routing Problem with Time Windows and Synchronised Visits", with Mateusz Polnik and Annalisa Ricardi, Forthcoming in Journal of the Operational Research Society, 2020.     Postprint      The final publication is available here: doi:10.1080/01605682.2020.1792365

26. "Robust Formulations for Economic Lot-Sizing Problem with Remanufacturing", with Oyku Naz Attila, Agostinho Agra and Ashwin Arulselvan, European Journal of Operational Research, 288(2):496-510, 2021     Postprint      The final publication is available here: doi: 10.1016/j.ejor.2020.06.016

25. "Passenger Demand Forecasting In Scheduled Transportation ", with Nilabhra Banerjee and Alec Morton, European Journal of Operational Research, 286(3):797-810, 2020.     Postprint      The final publication is available here: doi:10.1016/j.ejor.2019.10.032

24. "MIP approaches for a lot sizing and scheduling problem on multiple production lines with scarce resources, temporary workstations, and perishable products", with Willy A.O. Soler and Maristela O. Santos, Forthcoming in Journal of the Operational Research Society, 2019.     Postprint      The final publication is available here: doi:10.1080/01605682.2019.1640588

23. "A Theoretical and Computational Analysis of Lot-sizing in Remanufacturing with Separate Setups", with Sharifah Aishah Syed Ali, Mahdi Doostmohammadi, and Robert van der Meer, International Journal of Production Economics, 203:276-285, 2018.     The final publication is available as Open Access here: doi:10.1016/j.ijpe.2018.07.002

22. "Valid Inequalities for Two-Period Relaxations of Big-Bucket Lot-Sizing Problems: Zero Setup Case ", with Mahdi Doostmohammadi, European Journal of Operational Research, 267(1):86-95, 2018.     Postprint      The final publication is available as Open Access at Science Direct via doi:10.1016/j.ejor.2017.11.014

21. "Modelling Crew Scheduling in Offshore Supply Vessels", with Alex Leggate, Seda Sucu and Robert van der Meer, Journal of the Operational Research Society, 69(6):959-970, 2018.     Postprint      The final publication is available here: doi:10.1080/01605682.2017.1390531

20. "A Mixed-Method Optimisation and Simulation Framework for Supporting Logistical Decisions during Offshore Wind Farm Installations", with Euan Barlow, Diclehan Tezcaner Öztürk, Matthew Revie, Evangelos Boulougouris, and Alexander H. Day, European Journal of Operational Research, 264(3):894-906, 2018.     Postprint      The final publication is available here: doi:10.1016/j.ejor.2017.05.043

19. "Editorial: Making an Impact with Optimization ", with Marco Laumanns and Gerhard-Wilhelm Weber, Optimization, 66(12):2087-2088, 2017.     Postprint      The final publication is available here: doi:10.1080/02331934.2017.1376830

18. "Centrality Analysis for Modified Lattices", with Martin Paton, and Desmond J. Higham, SIAM Journal on Matrix Analysis and Applications, 38(3):1055–1073, 2017.     Postprint      The final publication is available here: doi:10.1137/17M1114247

17. "A Decomposition Algorithm for Robust Lot Sizing Problem with Remanufacturing Option", with Oyku Naz Attila, Agostinho Agra and Ashwin Arulselvan, In: Gervasi O. et al. (eds), International Conference on Computational Science and Its Applications (ICCSA 2017), Trieste, Italy. Lecture Notes in Computer Science (LNCS), Vol. 10405, Springer, pp.684-695, 2017.     Postprint      The final publication is available at Springer via doi: 10.1007/978-3-319-62395-5_47

16. "A Hybrid Integer and Constraint Programming Approach to Solve Nurse Rostering Problems", with Erfan Rahimian and John Levine, Computers & Operations Research, 82:83-94, 2017.     Postprint      The final publication is available here: doi:10.1016/j.cor.2017.01.016

15. "Progressive Selection Method for the Coupled Lot-Sizing and Cutting-Stock Problem", with Tao Wu, Raf Jans and Zhe Liang, INFORMS Journal on Computing, 29(3):523-543, 2017.     Technical Report     The final publication is available here: doi:10.1287/ijoc.2017.0746

14. "A Hybrid Integer Programming and Variable Neighbourhood Search Algorithm to Solve Nurse Rostering Problems", with Erfan Rahimian and John Levine, European Journal of Operational Research, 258(2):411-423, 2017.     Postprint      The final publication is available here: doi:10.1016/j.ejor.2016.09.030

13. "Network Models and Biproportional Apportionment for Fair Seat Allocations in the UK Elections", with Phil Knight, Annals of Operations Research, 253(1):1-19, 2017.     Technical Report      The final publication is available as Open Access at Springer via doi:10.1007/s10479-016-2323-0

12. "Economic Lot-Sizing Problem with Remanufacturing Option: Complexity and Algorithms", with Ashwin Arulselvan, In: Pardalos P., Conca P., Giuffrida G., Nicosia G. (eds), Machine Learning, Optimization, and Big Data: Second International Workshop, MOD 2016, Volterra, Italy. Lecture Notes in Computer Science (LNCS), Vol. 10122, Springer, pp. 132-143, 2016.      The final publication is available at Springer via doi:10.1007/978-3-319-51469-7_11

11. "Local Cuts and Two-Period Convex Hull Closures for Big-Bucket Lot-Sizing Problems", with Ioannis Fragkos, Andrew J. Miller and Tao Wu, INFORMS Journal on Computing, 28(4):766-780, 2016.     The final publication is available as Open Access here: doi:10.1287/ijoc.2016.0712

10. "Exploring the impact of innovative developments to the installation process for an offshore wind farm", with Euan Barlow, Diclehan Tezcaner Öztürk, Matthew Revie, Evangelos Boulougouris, and Alexander H. Day, Ocean Engineering, 109:623-634, 2015.     Postprint      The final publication is available here: doi:10.1016/j.oceaneng.2015.09.047

9. "A relax-and-fix with fix-and-optimize heuristic applied to multi-level lot-sizing problems", with Claudio Fabiano Motta Toledo, Márcio da Silva Arantes, Marcelo Yukio Bressan Hossomi and Paulo Morelato França, Journal of Heuristics, 21(5):687-717, 2015.     Postprint      The final publication is available at Springer via doi:10.1007/s10732-015-9295-0.

8. "A unified mixed-integer programming model for simultaneous fluence weight and aperture optimization in VMAT, Tomotherapy, and Cyberknife", with Vicky Mak and Thu Tran, Computers & Operations Research, 56:134–150, 2015.     Postprint      The final publication is available here: doi:10.1016/j.cor.2014.11.009

7. "Mixed Integer Programming in Production Planning with Backlogging and Setup Carryover", with Tao Wu,   Jie Song,  Leyuan Shi, Discrete Event Dynamic Systems, 23(2):211-239, 2013.     Preprint      The final publication is available here: doi:10.1007/s10626-012-0141-3

6. "Airline Planning Benchmark Problems. Part II: Passenger Groups, Utility and Demand Allocation", with  Natashia Boland,   Ian Evans,  Mark Wallace,  Hamish Waterer, Computers & Operations Research, 40(3):793–804, 2013.     Preprint      The final publication is available here: doi:10.1016/j.cor.2012.03.005

5. "Airline Planning Benchmark Problems. Part I: Characterising Networks and Demand using Limited Data", with  Natashia Boland,   Ian Evans,  Mark Wallace,  Hamish Waterer, Computers & Operations Research, 40(3):775–792, 2013.     Preprint      The final publication is available here: doi:10.1016/j.cor.2012.02.012

4. "On the Equivalence of Strong Formulations for Capacitated Multi-level Lot Sizing Problems with Setup Times", with Tao Wu,  Leyuan Shi,  Joseph Geunes, Journal of Global Optimization, 53(4): 615-639, 2012.   The final publication is available here: doi:10.1007/s10898-011-9728-8

3. "A Computational Analysis of Lower Bounds for Big Bucket Production Planning Problems", with Andrew J. Miller, Computational Optimization and Applications, 53(3):729-753, 2012.     Preprint    Also available from SpringerLink: doi:10.1007/s10589-012-9465-z

2. "An Optimization Framework for Solving Capacitated Multi-level Lot-sizing Problems with Backlogging", with Tao Wu,  Leyuan Shi,  Joseph Geunes, European Journal of Operational Research, 214(2): 428-441, 2011.     The final publication is available here: doi:10.1016/j.ejor.2011.04.029

1. "A Heuristic Approach for Big Bucket Multi-Level Production Planning Problems", with Andrew J. Miller, European Journal of Operational Research, 193: 396-411, 2009.     Preprint      Details of tests and codes       The final publication is available here: doi:10.1016/j.ejor.2007.11.033