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Abstract:
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Intermodal transport involves traffic with more than one type of trans port. Its presence in practice has become very significant. Bearing in mind that
these are mostly long distances, optimization has become important in this area.
By default, three standard types of containers of different sizes are used for the
transport. In accordance with the given criteria adequate mathematical models have
been developed. Based on the model, the exact solver CPLEX was programmed,
which succeeds to find the optimal solutions for lesser values of the input parameters.
For a number of models, solutions have been implemented in the C programming
language. The input data for smaller instances was taken from the practice. To
test instances of larger size, the input data is randomly generated from the selected
domain. In the first part of this work the main focus is the search for the optimal
route in transportation, according to the given criteria, which includes ocean and
mainland transport. The problem becomes more complex by increasing the number
of shipping companies, the number of side ports, as well as the number of modes of
transport on land. In the second part of the paper, additional problems related to
the optimization of intermodal transport are considered. More attention is paid to
the individual packages by considering the mass and volume of the package, and sub sequently the limits of mass and volume of the containers. One of solved problems
is related to the deployment of a large pack in several containers, then the selection
of optimal allocation in accordance with the set criteria. The second solved problem
is from the aggregate container transport and it is related to the deployment of a
large number of packages into containers, taking the constraints of mass and volume
into consideration. Here we also seek an optimal allocation in accordance with the
set criteria, eg. the total minimum price. The problem thus considered to belong
to the heterogeneous and homogeneous vector bin packing. The numerous com puter implementations of exact and approximate methods for the different models
are made. Variant methods of Variable Neighborhood Search (VNS) and GRASP
(Greedy Randomized Adaptive Search Procedures) have been designed to optimize
the aggregate container transport. These approximation methods were compared
with each other as well as with solutions obtained by exact solver CPLEX. |