Ph.D. Student
Operations Research and Combinatorial Optimization
Design and Analysis of Algorithms
Heuristics and Exact approaches
Data Science and Machine Learning
2022
Abstract
In this work, we propose the Dengue Prize-collecting Arc
Routing Problem (Dengue-PARP), which is the problem of finding
optimal routes for spraying vehicles as a control measure of
the mosquito population growth. In Dengue-PARP, each arc of a
street block has a prize value related to the number of dengue
cases. The goal of the Dengue-PARP is to maximize the prize
collected in order to create a route that covers a subset of
blocks. This work formulated the Dengue-PARP as an Integer
Programming (IP) model, subjected to computational experiments
with a set of 39 real-world instances with confirmed notified
cases. The methodology achieved optimal values for 31
instances, being all the 25 instances that contain up to 372
vertices, and 6 of the largest instances, containing up to
1212 vertices. The model also obtained feasible solutions for
the 8 remaining instances.
08/2022
Abstract
In this work, we propose and explore a new variant of the Multicast Routing
Problem (MRP) called Maximum Service in Multicast Routing with
Quality of Service constraints (MS-MRP-QoS) applied in the context of
vehicular ad-hoc networks, for which data must be sent from a root node to a set of
terminal nodes. The use of all nodes is not mandatory and each connection
between the root and a terminal aims to satisfy the quality of service according
to the limits established for each metric. The objective is to maximize the
number of serviced terminals according to the network's quality of service
metrics. We present an integer programming formulation and four Lagrangian
relaxations, to obtain good primal and dual bounds. We also develop a local
search applied during the resolution of the Lagrangian relaxations. These
methodologies were subjected to computational experiments with a set of 40
instances generated with characteristics of vehicular ad-hoc networks.
Statistical analyzes were performed to compare the performances among the
methodologies, and the results highlight the effectiveness of the approaches,
since the model achieved optimal values for 29 instances, while the Lagrangian
relaxations obtained competitive bounds, especially for large instances.
05/2022
Abstract
This work addresses the problem of Maximum Service in Multicast
Routing with Quality of Service constraints (MS-MRP-QoS) applied
in the context of vehicular ad-hoc networks, where a vehicle
network is provided for which it is desired send data from a
root node to a set of terminal nodes. The use of all nodes is
not mandatory and each connection between the root node and a
terminal must satisfy the quality of service according to the
limits established for each metric. The objective is to maximize
the number of terminals served according to the network's
quality of service metrics. In this dissertation, formulations
of mixed integer programming and four Lagrangian relaxations
were developed, aiming to obtain good quality primal and dual
limits. A set of heuristics methods has also been developed,
among them a local search in arborescences, applied during the
resolution of the Lagrangian relaxations, and three BRKGA
meta-heuristics with variations in the decoding method, one of
them incorporating information from the Lagrange multipliers.
The proposed methodologies were subjected to computational
experiments with a set of instances generated with
characteristics of ad-hoc vehicular networks. Statistical
analyzes were performed to compare the performances between the
methodologies. The results highlight the effectiveness of the
mixed integer formulation in obtain high quality primal and dual
limits for all instances of the set. The integer formulation,
Lagrangian relaxations and BRKGA obtained good quality solutions
and statistically similar.
02/2018
Abstract
The Max-Cut problem consists of partitioning a set of n nodes
into two subsets so that the sum of the edges between the
subsets is large as possible. This Course Completion Paper
presents 4 new versions of heuristics algorithms, based on
Genetic Algorithm and Simulated Annealing, which use a set of
valid inequalities in their structure. To the best of our
knowledge, we are the first to use valid inequalities in the
construction of metaheuristics for the Max-Cut Problem. The
results of the computational experiments show that the use of
these inequalities causes the algorithms to obtain better
results than the classical version, that is, without the
inequalities and also, in some cases, competitive with the state
of the art for Max Cut.
08/2018
Abstract
In the Maximally Diverse Grouping Problem, are given as input
data a set of n elements and a function that provides the
diversity degree between pair of elements. The problem is
NP-hard and it aims at partitioning the set of elements into
smaller subsets, called groups, in such a way that the diversity
between the elements belonging to each group is as large as
possible. In this paper, we present an integer linear
programming model for this problem. The results from
computational experiments show that the proposed model performs
better when compared with the quadratic one from the literature.
10/2018
Coming soon.
09/2018
Coming soon.
08/2017
Coming soon.
09/2009
Designed and developed by: Thomas Dillan