There has been a growing interest in location problems for their wide use in many 
areas, such as passive optical networks and logistics networks. However, as the 
papers appear in different literature, researchers usually do not take advantage 
of their mutual findings. We propose to bridge the gaps and therefore to propose 
efficient solutions schemes for two different applications.
 
In the first application, our research goal is to investigate the FTTX (Fiber-to-the 
Home/Premises/Curb) passive optical network (PON) for the deployment of broadband
access. We focus on designing the best possible architectures of FTTX hybrid PONs, 
which embraces both Time Division Multiplexing (TDM) and Wave Division 
Multiplexing (WDM) technology. A hybrid PON architecture is very efficient as it 
is not limited to any specific PON technology, rather it is flexible enough to deploy 
TDM/WDM technology depending on the type (i.e., unicast/multicast) and amount 
of traffic demand of the end-users. We investigate the optimized covering of a geographical 
area by a set of cost-effective hybrid PONs. We propose a novel network design 
optimization scheme for greenfield deployment of a set of hybrid PONs, in which all 
significant constraints are taken into account, e.g., type of traffic, attenuation, choice of 
splitting equipment.
 
In the second application, we revisit the p-center location problem in the context of 
disruption events. We propose an optimized covering in the geographical area for a 
given number of customers and suppliers, ensuring each customer is assigned a 
primary supplier and a different backup supplier unless the primary supplier has a 
so-called fortified facility. However, the budget for facility fortification is limited and 
only few facilities can be fortified. We design an optimization model under the assumption 
of single event disruptions, and estimate accurately the required facility capacities while 
taking into account a sharing of the backup resources.
 
We evaluate our proposed models and algorithms by a comprehensive set of numerical 
experiments, with some comparisons in each of these two applications. Conclusions are 
drawn in the last chapter.