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Vaccine Delivery in Developing Countries . Aakashi Kapoor, Caroline Krejci, Trond Nilsen. Health Center 1. Health Center 2. Health Center 3. Health Center 4. Health Center 5. Health Center 6. Health Center 7. “Last-Mile” Vaccine Distribution: Current System. Provincial Center.
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Vaccine Delivery in Developing Countries Aakashi Kapoor, Caroline Krejci, Trond Nilsen
Health Center 1 Health Center 2 Health Center 3 Health Center 4 Health Center 5 Health Center 6 Health Center 7 “Last-Mile” Vaccine Distribution: Current System Provincial Center District Center 1 District Center 2 District Center 3 Aakashi Kapoor, Caroline Krejci, Trond Nilsen
Health Center 1 Health Center 2 Health Center 3 Health Center 4 Health Center 5 Health Center 6 Health Center 7 “Last-Mile” Vaccine Distribution: Proposed System Provincial Center Aakashi Kapoor, Caroline Krejci, Trond Nilsen
Costs of Proposed System • Vehicle purchase price • Determined by vehicle type • Vehicle type defined by carrying capacity • Operating costs: • Vehicle maintenance & repair costs • Fuel costs • Salaries Aakashi Kapoor, Caroline Krejci, Trond Nilsen
Problem Statement • Fleet mix varies • Cost • Capacity • Fleet size varies • Single depot • Vehicles must return home • Some routes penalized • Danger • Difficulty Aakashi Kapoor, Caroline Krejci, Trond Nilsen
Formulation - I • Vehicle types ordered by ascending capacity • That is, a0 < a1 < ... < aK • Only one vehicle visits each node • Variable cost in fuel, personnel, maintenance, and penalty costs Aakashi Kapoor, Caroline Krejci, Trond Nilsen
Formulation - II Aakashi Kapoor, Caroline Krejci, Trond Nilsen
Formulation - III Aakashi Kapoor, Caroline Krejci, Trond Nilsen
Variations of VRP Aakashi Kapoor, Caroline Krejci, Trond Nilsen • Routing with time windows • Vaccine must be delivered within a time window, anything besides that incurs cost. • Multiple Depots • Another vector for nodes introduced to keep track of each depot • Deliveries in some days • Generalization of VRP with Vaccines delivered over period of M days instead of 1. • Split Delivery Routing • More than one vehicle serving the same customer.
Solution Techniques Aakashi Kapoor, Caroline Krejci, Trond Nilsen • Exact Approaches • Branch and bound (only up to 100 nodes) • Branch and cut – combination of cutting plane and branch and bound. • Heuristic Approaches • Savings heuristics – Clark and Wright – most used algorithm for VRP • Meta heuristics • Ant algorithms • Simulated annealing • Tabu search
Questions? Aakashi Kapoor, Caroline Krejci, Trond Nilsen