2 research outputs found
A Group Theoretic Tabu Search Methodology for Solving the Theater Distribution Vehicle Routing and Scheduling Problem
The application of Group Theory to Tabu Search is a new and exciting field of research. This dissertation applies and extends some of Colletti\u27s (1999) seminal work in group theory and metaheuristics in order to solve the theater distribution vehicle routing and scheduling problem (TDVRSP). This research produced a robust, efficient, effective and flexible generalized theater distribution model that prescribes the routing and scheduling of multi-modal theater transportation assets to provide economically efficient time definite delivery of cargo to customers. In doing so, advances are provided in the field of group theoretic tabu search and its application to difficult combinatorial optimization problems, e.g., the multiple trip multiple services vehicle routing and scheduling problem with hubs and other defining constraints
Optimization of transportation requirements in the deployment of military units
Cataloged from PDF version of article.We study the deployment planning problem (DPP) that may roughly be
defined as the problem of the planning of the physical movement of military
units, stationed at geographically dispersed locations, from their home bases
to their designated destinations while obeying constraints on scheduling and
routing issues as well as on the availability and use of various types of
transportation assets that operate on a multimodal transportation network.
The DPP is a large-scale real-world problem for which no analytical models
are existent. In this study, we define the problem in detail and analyze it with
respect to the academic literature. We propose three mixed integer
programming models with the objectives of cost, lateness (the difference
between the arrival time of a unit and its earliest allowable arrival time at its
destination), and tardiness (the difference between the arrival time of a unit
and its latest arrival time at its destination) minimization to solve the
problem. The cost-minimization model minimizes total transportation cost of
a deployment and is of use for investment decisions in transportation
resources during peacetime and for deployment planning in cases where the operation is not imminent and there is enough time to do deliberate planning
that takes costs into account. The lateness and tardiness minimization models
are of min-max type and are of use when quick deployment is of utmost
concern. The lateness minimization model is for cases when the given fleet of
transportation assets is sufficient to deploy units within their allowable time
windows and the tardiness minimization model is for cases when the given
fleet is not sufficient. We propose a solution methodology for solving all
three models. The solution methodology involves an effective use of
relaxation and restriction that significantly speeds up a CPLEX-based branchand-bound.
The solution times for intermediate sized problems are around
one hour at maximum for cost and lateness minimization models and around
two hours for the tardiness minimization model. Producing a suboptimal
feasible solution based on trial and error methods for a problem of the same
size takes about a week in the current practice in the Turkish Armed Forces.
We also propose a heuristic that is essentially based on solving the models
incrementally rather than at one step. Computational results show that the
heuristic can be used to find good feasible solutions for the models. We
conclude the study with comments on how to use the models in the realworld.Akgün, İbrahimPh.D