Geraldo Mateus | UFMG - The Federal University of Minas Gerais (original) (raw)

Papers by Geraldo Mateus

In this paper, we consider the capacitated three-level lot-sizing and replenishment problem with ... more In this paper, we consider the capacitated three-level lot-sizing and replenishment problem with a distribution structure (3LSPD-C), recently proposed in the literature. In 3LSPD-C, a single production plant delivers items to the warehouses from where they are distributed to their corresponding retailers. There is a capacity on the total amount the plant can produce in each period, whereas there are no capacities on transportation. The goal of this optimization problem consists in determining an integrated three-echelon production and distribution plan minimizing the total cost, which is composed of fixed costs for production and transportation setups as well as variable inventory holding costs. Additionally, we consider a generalization of the problem which also establishes storage capacities (or inventory bounds) on the warehouses and/or retailers, given the importance of such characteristics in practical industrial and commercial environments. Such extension is denoted generalize...

The Team Orienteering Problem (TOP) is an NP-hard routing problem in which a fleet of identical v... more The Team Orienteering Problem (TOP) is an NP-hard routing problem in which a fleet of identical vehicles aims at collecting rewards (prizes) available at given locations, while satisfying restrictions on the travel times. In TOP, each location can be visited by at most one vehicle, and the goal is to maximize the total sum of rewards collected by the vehicles within a given time limit. In this paper, we propose a generalization of TOP, namely the Steiner Team Orienteering Problem (STOP). In STOP, we provide, additionally, a subset of mandatory locations. In this sense, STOP also aims at maximizing the total sum of rewards collected within the time limit, but, now, every mandatory location must be visited. In this work, we propose a new commodity-based formulation for STOP and use it within a cutting-plane scheme. The algorithm benefits from the compactness and strength of the proposed formulation and works by separating three families of valid inequalities, which consist of some gen...

In this paper, we propose a novel heuristic for the wireless sensor network localization problem.... more In this paper, we propose a novel heuristic for the wireless sensor network localization problem. Experimental results illustrate the relative effectiveness of our algorithm on several different network topologies and size, in the presence or absence of noise, and networks of different radio range and/or number of anchors and/or noise factor.

Proceedings of the 12th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems - MSWiM '09, 2009

Page 1. Hybrid Multiobjective Approach for Designing Wireless Sensor Networks Flávio VC Martins D... more Page 1. Hybrid Multiobjective Approach for Designing Wireless Sensor Networks Flávio VC Martins Dept. of Electrical Engineering UFMG Belo Horizonte, Brazil cruzeiro@dcc. ufmg.br Eduardo G. Carrano Dept. of Electrical Engineering ...

IEEE Sensors Journal, 2011

The increasing in the demand for Wireless Sensor Networks (WSNs) has intensified studies which ar... more The increasing in the demand for Wireless Sensor Networks (WSNs) has intensified studies which are dedicated to obtain more energy-efficient solutions, since the energy storage limitation is critical in those systems. Additionally, there are other aspects which usually must be ensured in order to get an accept- able performance of WSNs, such as area coverage and network connectivity. This paper proposes a procedure for enhancing the performance of WSNs: a multiobjective hybrid optimization algorithm is employed for solving the Dynamic Coverage and Connectivity Problem (DCCP) in flat WSNs subjected to node failures. This method combines a multiobjective global on-de- mand algorithm (MGoDA), which improves the current DCCP solution using a Genetic Algorithm, with a local on line algorithm (LoA), which is intended to restore the network coverage soon after any failure. The proposed approach is compared with an Integer Linear Programming (ILP)-based approach and a similar mono-objective approach with regard to coverage, network life- time and required running time for achieving the optimal solution provided by each method. Results achieved for a test instance show that the hybrid approach presented can improve the performance of the WSN obtaining good solutions with a considerably smaller computational time than ILP. The multiobjective approach still provides a feasible method for extending WSNs lifetime with slight decreasing in the network mean coverage.

Evolutionary Computation, 2014

Recent works raised the hypothesis that the assignment of a geometry to the decision variable spa... more Recent works raised the hypothesis that the assignment of a geometry to the decision variable space of a combinatorial problem could be useful both for providing meaningful descriptions of the fitness landscape and for supporting the systematic construction of evolutionary operators (the geometric operators) that make a consistent usage of the space geometric properties in the search for problem optima. This paper introduces some new geometric operators that constitute the realization of searches along the combinatorial space versions of the geometric entities descent directions and subspaces. The new geometric operators are stated in the specific context of the wireless sensor network dynamic coverage and connectivity problem (WSN-DCCP). A genetic algorithm (GA) is developed for the WSN-DCCP using the proposed operators, being compared with a formulation based on integer linear programming (ILP) which is solved with exact methods. That ILP formulation adopts a proxy objective funct...

2010 IEEE/ACM 14th International Symposium on Distributed Simulation and Real Time Applications, 2010

Page 1. An Evolutionary Dynamic Approach for Designing Wireless Sensor Networks for Real Time Mon... more Page 1. An Evolutionary Dynamic Approach for Designing Wireless Sensor Networks for Real Time Monitoring Flávio VC Martins ∗ , Eduardo G. Carrano , Elizabeth F. Wanner , Ricardo HC Takahashi and Geraldo R. Mateus § ...

The Steiner Team Orienteering Problem (STOP) is defined on a digraph in which arcs are associated... more The Steiner Team Orienteering Problem (STOP) is defined on a digraph in which arcs are associated with traverse times, and whose vertices are labeled as either mandatory or profitable, being the latter provided with rewards (profits). Given a homogeneous fleet of vehicles M, the goal is to find up to m = |M| disjoint routes (from an origin vertex to a destination one) that maximize the total sum of rewards collected while satisfying a given limit on the route's duration. Naturally, all mandatory vertices must be visited. In this work, we show that solely finding a feasible solution for STOP is NP-hard and propose a Large Neighborhood Search (LNS) heuristic for the problem. The algorithm is provided with initial solutions obtained by means of the matheuristic framework known as Feasibility Pump (FP). In our implementation, FP uses as backbone a commodity-based formulation reinforced by three classes of valid inequalities. To our knowledge, two of them are also introduced in this ...

Anais do XXXIX Simpósio Brasileiro de Redes de Computadores e Sistemas Distribuídos (SBRC 2021)

A Virtualização de Funções de Rede emerge com intuito de reduzir custos operacionais e prover ﬂex... more A Virtualização de Funções de Rede emerge com intuito de reduzir custos operacionais e prover ﬂexibilidade no atendimento dos novos serviços de rede. Um dos principais desaﬁos em tais ambientes é posicionar e encadear com eﬁciência as funções virtuais de rede sobre máquinas virtuais alocadas em servidores da rede física. Por se tratar de um ambiente online, as abordagens utilizadas devem gerar uma tomada de decisão rápida sobre o mapeamento, ou não, de uma requisição. Neste contexto, uma abordagem baseada nas metaheurísticas Greedy Randomized Adaptive Search Procedure e Variable Neighborhood Search foi proposta, e comparada a um método exato. Experimentos computacionais mostram que o método exato, apesar de gerar maiores lucros, possui um tempo de execução elevado. No entanto, a abordagem heurística apresentou um tempo de execução até 810% menor, reduziu o atraso ﬁm a ﬁm em até 70%, mas ao custo de uma queda no compartilhamento de servidores de até 25%, e no lucro de até 11%.

Network virtualization has gained visibility by enabling the development of new functionalities a... more Network virtualization has gained visibility by enabling the development of new functionalities and applications for the internet. With virtualization, a logical view of the hardware is created so that multiple virtual networks can coexist on the same physical network substrate. The virtual network embedding problem belongs to the NP-hard class not allowing the use of exact approaches. In this work, the application of a fast heuristic approach in a multidomain, decentralized and online environment is proposed, through an orchestrator's control. A comparative study regarding the implementation of three different orchestration models is presented: total knowledge, partial and without knowledge of the internal physical network infrastructure of the domains. Experimental results show the performance of the orchestrator along with the heuristic, reporting energy consumption, profit generation and message exchange metrics for the different approaches.

We propose an in-depth study of the reconfiguration problem in multi-fiber WDM networks. It consi... more We propose an in-depth study of the reconfiguration problem in multi-fiber WDM networks. It consists in defining how to adapt the optical layer to changing traffic patterns. Our objective is to treat the problem globally. We consider arbitrary mesh topology, all-to-all traffic and multi-hop routing. However, we restrict ourselves to prevision: the traffic evolutions are foreseen. We propose a compact Mixed Integer Linear Programming model, allowing to solve medium instances. We define many metrics to evaluate the performance of a solution. We also propose some mathematical cuts and a lower bound for the problem. We make extensive experiments based on this model, in order to find out the influence of different parameters, such as the metric chosen or the cut formulation. To do so, many instances were solved with different networks.

This work implements an Hybrid Algorithm (HA) that combines exact and heuristic algorithms to sol... more This work implements an Hybrid Algorithm (HA) that combines exact and heuristic algorithms to solve the static Vehicle Routing Problem (VRP). Different runs of the Simulated Annealing generate heuristically columns for the mathematical model of the Set Partitioning Problem (SPP), which is solved during the second step of the HAA through the CPLEX package. The main goal of the research was to generate an efficient algorithm to the static VRP, that would serve as basis for online algorithms to solve the dynamic VRP. For two instances of Solomon’s benchmark new and better results were reached in this research.

This paper adapts the GRASP with path-relinking heuristic introduced by Mateus et al. (2011) for ... more This paper adapts the GRASP with path-relinking heuristic introduced by Mateus et al. (2011) for the generalized quadratic assignment problem (GQAP), for a novel problem denominated multi-tap single-finger keypad layout problem (MTSFKLP). The MTSFKLP consists in assigning symbols (characters) of a language to keys of a keypad such that the total area of the symbols assigned to a key does not exceed the available area of the key. Among all feasible assignments, we seek one that minimizes the sum of products of frequency of the transition between each pair of consecutive characters and distances between keys to which the characters pairs are assigned.

CONTEXT: Researchers and practitioners related to Project Management have been very successful in... more CONTEXT: Researchers and practitioners related to Project Management have been very successful in supporting the project manager needs. Despite all the successes in developing a number of tools and guides, a reasonable amount of concepts and practices in software project management is not based on a principled reasoning. Search-based Software Engineering is a recent eld of research that applies Optimization techniques to Software Engineering problems, including the ones in Software Project Management and, in particular, software project scheduling and stang. The goal of these optimization techniques is to help the management decision making based on solid reasoning. OBJECTIVE: This paper aims to characterize the concepts used to model the software project scheduling and stang problem and to evaluate the strategies used to assess the results. METHOD: We performed a systematic literature review that focuses on reports describing optimization techniques applied to schedule and to sta s...

In this paper we study a Three-Dimensional Bin Packing Problem specialization. Given a certain am... more In this paper we study a Three-Dimensional Bin Packing Problem specialization. Given a certain amount of goods with variable dimensions and weights and a fleet of trucks of different types, the problem consist of allocating the goods in the fleet so as to minimize the empty space. Each good also has a status wich varies according to the urgency of its delivery, the higher being this urgency, the higher being the priority of such delivery. The problem was modeled as a Mixed Integer Programming Problem and solved by CPLEX. We have tested the proposed model using data from a big brazilian company wich, interested in the project, has agreed to provide us with information about its operation. The results for these tests are reported here and compared to an heuristic that simulates the manual allocation of the goods, currently employed by companies with no specific software for this task.

The network resource allocation is considered an NP-hard problem, present in Virtual Network Embe... more The network resource allocation is considered an NP-hard problem, present in Virtual Network Embedding (VNE) and the Virtual Network Function (NFV). In this context, a little-explored question in the literature is related to when to apply an exact or heuristic resolution method. For both VNE and NFV, the literature usually suggests a heuristic treatment, considered the complexity and the high dimension of the data. However, in preliminary experiments, it is possible to observe that occasionally, the exact treatment can be applied in a practicable time. It is inferred that these events are not casual; they come from several conditions related to the residual Network Substrate (SN) and the network demands requested. The approach proposed in this paper is based on the application of the Machine Learning (ML) technics in order to allocate the network resources and aims to predict the situations in which the exact approach could supersede the heuristic. For this purpose, the VNE and both...

Wireless networks are becoming more and more popular and traffic over the networks is growing rap... more Wireless networks are becoming more and more popular and traffic over the networks is growing rapidly. Because the network infrastructure is expanding at a quick pace, especially the wireless Internet growth , both in size and in the types of applications, the performance issue and dimensioning issue of networks are becoming more critical. New wireless data applications are emerging over mobile telecommunication networks. These applications produce data that may have different characteristics from those of wired dada applications. In this case, a good evaluation of performance measures can help a system designer to make its strategic decisions concerning cell size and the number of channel frequencies allocated to each cell. In this paper we present a data services analysis in a mobile telecommunication networks based on simulation. In addition, we illustrate the need for a simulation in order to characterize the mix of several traffic types for capacity and quality of service (QoS)...

This article describes the study of a supply chain, focusing on related sustainability applicatio... more This article describes the study of a supply chain, focusing on related sustainability applications. Due to the considerable efforts necessary to an exact solver to resolve the problem, a genetic algorithm is proposed, which consumes less computational resources, such as processing time. In more than 88% of cases, the proposed algorithm returns the optimal solution to the problem. Nevertheless, in the cases in which the problem is not solved to optimality, the optimality gap is less than 7%.

2019 15th International Conference on Network and Service Management (CNSM)

Virtual Network Functions (VNF) reduce the complexity to deploy a Network Service (NS), yielding ... more Virtual Network Functions (VNF) reduce the complexity to deploy a Network Service (NS), yielding flexibility, and scalability to attend new market appliances and minimizing the required investments. An ordered set of VNFs to serve a NS is called a Service Function Chain (SFC). Most of the literature works deal with SFCs generation and embedding as independent problems, not taking into account the residual substrate network (SN) status during the SFCs generation stage. Furthermore, a NS can award some flexibility regarding the VNFs sequence, i.e., only a subset of VNFs have a fixed precedence requirement. Following this idea, the network operator may enjoy some options to serve a NS. In this work, we introduce a new embedding approach which selects the SFC composition that best fits the residual SN, leading to a better performance in the chaining and placement of VNFs. The results showed that the composition selection mechanism increases performance compared to traditional models that use a fixed composition, improving resources sharing, and increasing the network operator revenues. Also, we demonstrated that the generation of an optimal SFC for a NS does not always lead to the best acceptance rates in a network with partially consumed resources.

Proceedings of the 12th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems - MSWiM '09, 2009

IEEE Sensors Journal, 2011

Evolutionary Computation, 2014

2010 IEEE/ACM 14th International Symposium on Distributed Simulation and Real Time Applications, 2010

Anais do XXXIX Simpósio Brasileiro de Redes de Computadores e Sistemas Distribuídos (SBRC 2021)

2019 15th International Conference on Network and Service Management (CNSM)