5 research outputs found
Traveling Salesman Problem
This book is a collection of current research in the application of evolutionary algorithms and other optimal algorithms to solving the TSP problem. It brings together researchers with applications in Artificial Immune Systems, Genetic Algorithms, Neural Networks and Differential Evolution Algorithm. Hybrid systems, like Fuzzy Maps, Chaotic Maps and Parallelized TSP are also presented. Most importantly, this book presents both theoretical as well as practical applications of TSP, which will be a vital tool for researchers and graduate entry students in the field of applied Mathematics, Computing Science and Engineering
Tactical Problems in Vehicle Routing Applications
The class of Vehicle Routing Problems (VRPs) is one the most
studied topics in the Operations Research community. The vast
majority of the published papers focus on single-period problems,
with a few branches of the literature considering multiperiod
generalisations. All of these problems though, consider a short
horizon and aim at optimising the decisions at an operational
level, i.e. that will have to be taken in the near future. One
step above are tactical problems, i.e. problems concerning a
longer time horizon. Tactical problems are of a fundamental
importance as they directly influence the daily operations, and
therefore a part of the incurred costs, for a long time. The main
focus of this thesis is to study tactical problems arising in
routing applications. The first problem considered concerns the
design of a fleet of vehicles. Transportation providers often
have to design a fleet that will be used for daily operations
across a long-time span. Trucks used for transportation are very
expensive to purchase, maintain or hire. On the other side, the
composition of the fleet strongly influences the daily plans, and
therefore costs such as fuel or drivers’ wages. Balancing these
two components is challenging, and optimisation models can lead
to substantial savings or provide a useful basis for informed
decisions.
The second problem presented focuses on the use of a split
deliveries policy in multi-period routing problems. It is known
that the combined optimisation of delivery scheduling and routing
can be very beneficial, and lead to significant reductions in
costs. However, it also adds complexity to the model. The same is
true when split deliveries are introduced. The problem studied
considers the possibility of splitting the deliveries over
different days. An analysis, both theoretical and numerical, of
the impact of this approach on the overall cost is provided.
Finally, a districting problem for routing applications is
considered. These types of problems typically arise when
transportation providers wish to increase their service
consistency. There are several reasons a company may wish to do
so: to strengthen the customer-driver relationship, to increase
drivers’ familiarity with their service area, or, to simplify
the management of the service area. A typical approach,
considered here, is to divide the area under consideration in
sectors that will be subsequently assigned to specific drivers.
This type of problem is inherently of a multi-period and tactical
nature. A new formulation is proposed, integrating standard
routing models into the design of territories. This makes it
possible to investigate how operational constraints and other
requirements, such as having a fair workload division amongst
drivers, influence the effectiveness of the approach. An analysis
of the cost of districting, in terms of increased routing cost
and decreased routing flexibility, and of several operational
constraints, is presented