• container inspection;
  • sensor sequencing;
  • linear programming


Cargo ships arriving at US ports are inspected for unauthorized materials. Because opening and manually inspecting every container is costly and time-consuming, tests are applied to decide whether a container should be opened. By utilizing a polyhedral description of decision trees, we develop a large-scale linear programming model for sequential container inspection that determines an optimal inspection strategy under various limitations, improving on earlier approaches in several ways: (a) we consider mixed strategies and multiple thresholds for each sensor, which provide more effective inspection strategies; (b) our model can accommodate realistic limitations (budget, sensor capacity, time limits, etc.), as well as multiple container types; (c) our model is computationally more tractable allowing us to solve cases that were prohibitive in preceding models, and making it possible to analyze the potential impact of new sensor technologies. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009