Chapter
1 Introduction to multicommodity network flow problems
[pdf:198kB] [ps:494kB]
In
this chapter, we first describe an air cargo flow problem
in the Asia Pacific region. It is this problem that motivates
our research. Because the problem can be modeled as a multicommodity
network flow (MCNF) problem, we then introduce many MCNF related
research topics and applications. Finally, we review different
MCNF formulations and outline this thesis.
Contributions and thesis outline
We consider the
following to be the major contributions of this thesis:
- We survey and summarize MCNF problems and algorithms
that have appeared in the last two decades.
- We survey and summarize shortest path algorithms that
have appeared in the last five decades.
- We observe the connection between a new shortest path
algorithm and the well-known Dijkstra's algorithm.
- We propose three new multiple pairs shortest paths
algorithms, discuss their theoretical properties, and
analyze their computational performance.
- We give two new MCNF algorithms, and compare their
computational performance with two standard MCNF algorithms.
This thesis has
six chapters. Chapter 1 discusses MCNF applications and their
formulations. Chapter 2 surveys MCNF solution techniques from
the literature. Since our approaches require us to solve many
multiple pairs shortest paths (MPSP) problems, we will propose
new efficient MPSP algorithms. Chapter 3 first reviews the
shortest path solution techniques that have appeared in the
last five decades, and then introduces a new shortest path
method which uses the nonnegative least squares (NNLS) technique
in the primal-dual (PD) algorithmic framework, and discusses
its relation to the well-known Dijkstra's algorithm. Chapter
4 discusses the theoretical details of our new MPSP algorithms.
Chapter 5 presents the computational performance of our new
MPSP algorithms. Finally, Chapter 6 illustrates our primal-dual
MCNF algorithms, analyzes their computational performance,
and suggests new techniques to improve the algorithms. Chapter
7 concludes this thesis and suggests future research. |