Frequency Assignments for HFDF Receivers in a Search and Rescue Network.

摘要

This thesis applies a multiobjective linear programming approach to the problem of assigning frequencies to HFDF receivers in a search-and-rescue network in order to maximize the expected number of geolocations of vessels in distress. The problem is formulated as a multiobjective integer linear programming problem. The integrality of the solutions is guaranteed by the totally unimodularity of the A-matrix. Two approaches are taken to solve the multiobjective linear programming problem. 1) The multiobjective simplex method as implemented in ADBASE; and 2) An iterative approach. In this approach, the individual objective functions are weighted and combined in a single additive objective function. The resulting single objective problem is expressed as a network programming problem and solved using SAS NETFLOW. The process is then repeated with different weightings for the objective functions. The solutions obtained from the multiobjective linear programs are evaluated using a FORTRAN program to determine which solution provides the greatest expected number of geolocations. This solution is then compared to the sample mean and standard deviation for the expected number of geolocations resulting from 10,000 random frequency assignments for the network. The best solution obtained using the multiobjective integer linear programming approach provided an approximate expected number of geolocations that was more than 13 standard deviations better than the mean approximate expected number of geolocations obtained from 10,000 randomly frequency assignments. Thus, the solutions obtained using this approach are significantly better than could be expected from an arbitrary frequency assignment. Theses. (edc)