Olinto Araujo

UFSM - Universidade Federal de Santa Maria, CTISM, Faculty Member

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Alysson M. Costa

Universidade de São Paulo

Jacqueline Bloemhof

Wageningen University

Ammar Al-Bazi

Aston University

Armin Lüer-Villagra

Universidad Andrés Bello

Hanne Thomas

FHNW

S.M.J. Mirzapour Al-E-Hashem

ESC RENNES SCHOOL OF BUSINESS

Jaime Antero Arango Marin

Universidad Nacional de Colombia (National University of Colombia)

Andres Medaglia

Universidad de los Andes (Colombia)

Fernando Sandoya Sánchez

ESPOL (Escuela Superior Politécnica del Litoral)

Duc Minh Vu

Loyola University Chicago

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Papers by Olinto Araujo

Algoritmo para o problema de seq�enciamento em m�quinas paralelas n�o-relacionadas

Comparative analysis of mathematical formulations for the two‐dimensional guillotine cutting problem

International Transactions in Operational Research

About 15 years ago, a paper proposed the first integer linear programming formulation for the con... more About 15 years ago, a paper proposed the first integer linear programming formulation for the constrained two‐dimensional guillotine cutting problem (with unlimited cutting stages). Since then, eight other formulations followed, seven of them in the last four years. This spike of interest gave no opportunity for a comprehensive comparison between the formulations. We review each formulation and compare their empirical results over instance datasets of the literature. We adapt most formulations to allow for piece rotation. The possibility of adaptation was already predicted but not realized by the prior work. The results show the dominance of pseudo‐polynomial formulations until the point instances become intractable by them, while more compact formulations keep achieving good primal solutions. Our study also reveals a mistake in the generation of the T instances, which should have the same optima with or without guillotine cuts. We also propose hybridising a recent formulation with ...

Mixed Integer Linear Programming Applied to Adaptive Directional Overcurrent Protection Considering N-1 Contingency

IEEE Transactions on Industry Applications

A New Approach for Directional Overcurrent Relays Coordination in Interconnected Power Systems

2020 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D LA)

This work presents a new approach for setting and coordinating directional overcurrent relays (DO... more This work presents a new approach for setting and coordinating directional overcurrent relays (DOCRs) in interconnected Power Systems using Constraint Programming. This technique, besides allowing the selection of settings, makes it possible to obtain the set of feasible values that can be selected. The methodology is applied in the 6 and 15 bus test systems to compare the results with other methods present in the literature, demonstrating substantial advantages.

Three-dimensional cutting and packing problems and integration with vehicle routing

Orientador: Vinicius Amaral ArmentanoTese (doutorado) - Universidade Estadual de Campinas, Faculd... more Orientador: Vinicius Amaral ArmentanoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de ComputaçãoResumo: A adoÃ§Ã£o de contÃªineres em grande escala tornou possÃvel o desenvolvimento do transporte multimodal. Atualmente, carregamento de caixas em contÃªineres Ã© uma importante atividade em empresas que tÃªm no transporte de carga um fator logÃstico de alto custo. Este trabalho apresenta o desenvolvimento e aplicaÃ§Ã£o de metaheurÃsticas com memÃ³ria adaptativa para a resoluÃ§Ã£o de problemas de corte e empacotamento tridimensional, bem como a integraÃ§Ã£o destes com o problema de roteamento de veÃculos. Mais especificamente, sÃ£o tratados os problemas de carregamento de contÃªiner, bin packing tridimensional e roteamento de veÃculos capacitados com restriÃ§Ãµes de empacotamento tridimensional. Uma nova abordagem, baseada em cubÃ³ides de tamanho variÃ¡vel, Ã© utilizada para calcular os padrÃµes de carregamento tridimensional em todos os ...

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Problemas de corte e empacotamento tridimensional e integração com roteamento de veiculos

... Page 5. v À minha esposa Mauren e ao meu filho Guilherme. Page 6. vi AGRADECIMENTOS ... desta... more

Enhanced Formulation for Guillotine 2D Cutting Problems

ArXiv, 2021

We advance the state of the art in Mixed-Integer Linear Programming (MILP) formulations for Guill... more We advance the state of the art in Mixed-Integer Linear Programming (MILP) formulations for Guillotine 2D Cutting Problems by (i) adapting a previouslyknown reduction to our preprocessing phase and by (ii) enhancing a previous formulation by cutting down its size and symmetries. Our focus is the Guillotine 2D Knapsack Problem with orthogonal and unrestricted cuts, constrained demand, unlimited stages, and no rotation – however, the formulation may be adapted to many related problems. The code is available. Concerning the set of 59 instances used to benchmark the original formulation, and summing the statistics for all models generated, the enhanced formulation has only a small fraction of the variables and constraints of the original model (respectively, 3.07% and 8.35%). The enhanced formulation also takes about 4 hours to solve all instances while the original formulation takes 12 hours to solve 53 of them (the other six runs hit a three-hour time limit each). We integrate, to bot...

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Advanced Real-Time Alarm Processor for Fault Section Estimation in Power Systems

This paper proposes an intelligent alarm processor dedicated to connect the Supervisory Control a... more This paper proposes an intelligent alarm processor dedicated to connect the Supervisory Control and Data Acquisition (SCADA) to fault diagnosis systems. The proposed alarm processor allows to reduce the number of reported alarms and to increase the speed and correctness of the diagnosis process. Algorithms were designed to filter alarms by equipment, to identify multiple events associated with a set of reported alarms, and to handle network topological changes for an effective system application. A Southern Brazilian power system was used to validate our approach. Computational experiments disclosed that the proposed approach can deal with topology changes and is able to generate a list of suspicious sections after fault disturbances.

A Column Generation Approach to High School Timetabling Modeled as a Multicommodity Flow Problem

European Journal of Operational Research, 2017

School timetabling is a classic optimization problem that has been extensively studied due to its... more School timetabling is a classic optimization problem that has been extensively studied due to its practical and theoretical importance. It consists in scheduling a set of class-teacher meetings in a predetermined period of time, satisfying requirements of different types. Given the combinatorial nature of this problem, solving medium and large instances of timetabling to optimality is a challenging task. When resources are tight, often it is difficult to find even a feasible solution. Several techniques have been developed in the literature to tackle the high school timetabling problem. Since the use of exact methods, as mathematical programming techniques, are considered impracticable to solve large real world instances, metaheuristics and hybrid metaheuristics are the most used solution approaches. In this paper we propose a multicommodity flow model for the high school timetabling problem. In addition, we apply Dantzig–Wolfe decomposition to the proposed model, propose a column generation algorithm, and present experimental results on well known instances of the problem. The results show that the lower bounds obtained through our approach are tight and can be generated faster than previous approaches reported in the literature.

A fix-and-optimize heuristic for the high school timetabling problem

Computers & Operations Research, 2014

The high school timetabling is a classical combinatorial optimization problem that takes a large ... more The high school timetabling is a classical combinatorial optimization problem that takes a large number of variables and constraints into account. Due to its combinatorial nature, solving medium and large instances to optimality is a challenging task. When resources are tight, it is often difficult to find even a feasible solution. Among the different requirements that are considered in Brazilian schools, two compactness requirements must be met on a teacher's schedule: the minimization of working days and the avoidance of idle timeslots. In this paper, we present a mixed integer linear programming model and a fix-and-optimize heuristic combined with a variable neighborhood descent method. Our method uses three different types of decompositions-class, teacher and dayin order to solve the high school timetabling problem. The method is able to find new best known solutions for seven instances, including three optimal ones. A comparison with results reported in the literature shows that the proposed fix-and-optimize heuristic outperforms state-of-the-art techniques for the resolution of the problem at hand.

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The Impact of compactness requirements on the resolution of high school timetabling problem

The school timetabling is a classic optimization problem that takes a large number of variables a... more The school timetabling is a classic optimization problem that takes a large number of variables and constraints into account. Due to the combinatorial nature of this problem, it is very difficult to solve it manually and is often difficult to find a feasible solution when resources are tight. Among the different requirements that are considered in Brazilian Schools, two compactness requirements are essential on a teacher's schedule: to minimize working days and to avoid idle times. In this work we explore the influence of four different idle times constraint formulations: two of them were previously proposed, and two are novel. Experimental results shown that a novel idle times constraint formulation produces better results for classical instances of the literature. One of these results is a new optimal solution and two of them are new best computed solutions. Finally, we also study the impact of double lessons and the minimization of working days in these formulations.

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Extending an Integer Formulation for the Guillotine 2D Bin Packing Problem

Procedia Computer Science

Service Restoration in Distribution Systems based on Multi-Objective Genetic Algorithm considering repair and switching time

2019 IEEE PES Innovative Smart Grid Technologies Conference - Latin America (ISGT Latin America), 2019

This paper present a multi-objective evolutionary algorithm for the Service Restoration Problem i... more This paper present a multi-objective evolutionary algorithm for the Service Restoration Problem in distribution systems. The criteria considered are non-energized load, number of switching operations, number of non-energized nodes and total switching time. An analysis of the solutions by the operator is illustrated using an estimation of the expected energy not supplied. The methodology has been evaluated on the 69 Node System Test.

Análise da Viabilidade Técnica de Manobras de Paralelismo entre Alimentadores de Distribuição Utilizando Chaves Monopolares

Primary distribution overhead networks usually operate radially. By opening or closing switches, ... more Primary distribution overhead networks usually operate radially. By opening or closing switches, it is possible to transfer load blocks between feeders. To avoid power shutdowns, temporary parallelism between feeders is an usual practice. The topology of the network can be changed during contingencies, normal operating condition or scheduled shutdowns. Some criteria of technical feasibility must be considered to define the conditions to make the parallelism. This article presents a study of parallelism maneuvers between two feeders from Electrical Energy Distribution State Company (CEEE-D), modeled on Alternative Transient Program (ATP) software. The maneuvers were simulated with single switches, evaluating the impact on overcurrent protection. For the network and the analyzed conditions, it was verified that the switching time is crucial for trip or not of the overcurrent protection of one of the feeders, making the maneuvers unfeasible. Resumo: As redes aéreas de distribuição prim...

New adaptive protection algorithm for online overcurrent relay setting in interconnected power systems

This work presents an adaptive protection algorithm for online coordination of directional overcu... more This work presents an adaptive protection algorithm for online coordination of directional overcurrent relays. The algorithm includes an optimization procedure for determining time and pick-up current settings in the coordination problem. The proposed algorithm is simulated in an interconnected system and the results shows that it is able to find the optimal solution in reduced times, highlighting its potential for online application and the need for such an algorithm to keep the system secure.

Arc-flow approach for single batch-processing machine scheduling

We address the problem of scheduling jobs with non-identical sizes and distinct processing times ... more We address the problem of scheduling jobs with non-identical sizes and distinct processing times on a single batch processing machine, aiming at minimizing the makespan. The extensive literature on this NP-hard problem mostly focuses on heuristics. Using an arc flow-based optimization approach, we construct an ingenious formulation that represents it as a problem of determining flows in graphs. The size of the formulation increases with the number of distinct sizes and processing times among the jobs, but it does not increase with the number of jobs, which makes it very effective to solve large instances to optimality, especially when multiple jobs have equal size and processing time. We compare our model to other models from the literature showing its clear superiority on benchmark instances, and proving optimality of random instances with up to 100 million jobs.

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Solid-state light simulator for horticultural applications

2017 Brazilian Power Electronics Conference (COBEP)

This work presents a flexible light simulator designed to reproduce precise conditions of both sp... more This work presents a flexible light simulator designed to reproduce precise conditions of both spectrum and intensity of light. The system consists of a combination of different LEDs defined by an optimized selection method. Buck converters under current-mode control are used to achieve the independent control of each LED model. Independent control of all light sources allows the possibility to vary intensity and spectral distribution of the light. As an example of application, an LED module is designed and implemented to meet the midday sunlight spectrum.

Conception and design of a lighting system based on Light Emitting Diodes for spectrum simulation

2016 12th IEEE International Conference on Industry Applications (INDUSCON), 2016

Study of rural administration in Pelotas

A Column Generation Approach to High School Timetabling Modeled as a Multicommodity Flow Problem

by Arton P Dorneles and Olinto Araujo

School timetabling is a classic optimization problem that has been extensively studied due to its... more School timetabling is a classic optimization problem that has been extensively studied due to its practical and theoretical importance. It consists in scheduling a set of class-teacher meetings in a predetermined period of time, satisfying requirements of different types. Given the combinatorial nature of this problem, solving medium and large instances of timetabling to optimality is a challenging task. When resources are tight, often it is difficult to find even a feasible solution. Several techniques have been developed in the literature to tackle the high school timetabling problem. Since the use of exact methods, as mathematical programming techniques, are considered impracticable to solve large real world instances, metaheuristics and hybrid metaheuristics are the most used solution approaches. In this paper we propose a multicommodity flow model for the high school timetabling problem. In addition, we apply Dantzig-Wolfe decomposition to the proposed model, propose a column generation algorithm, and present experimental results on well known instances of the problem. The results show that the lower bounds obtained through our approach are tight and can be generated faster than previous approaches reported in the literature.

Algoritmo para o problema de seq�enciamento em m�quinas paralelas n�o-relacionadas

Comparative analysis of mathematical formulations for the two‐dimensional guillotine cutting problem

International Transactions in Operational Research

Mixed Integer Linear Programming Applied to Adaptive Directional Overcurrent Protection Considering N-1 Contingency

IEEE Transactions on Industry Applications

A New Approach for Directional Overcurrent Relays Coordination in Interconnected Power Systems

2020 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D LA)

Three-dimensional cutting and packing problems and integration with vehicle routing

Download

Problemas de corte e empacotamento tridimensional e integração com roteamento de veiculos

... Page 5. v À minha esposa Mauren e ao meu filho Guilherme. Page 6. vi AGRADECIMENTOS ... desta... more

Enhanced Formulation for Guillotine 2D Cutting Problems

ArXiv, 2021

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Advanced Real-Time Alarm Processor for Fault Section Estimation in Power Systems

A Column Generation Approach to High School Timetabling Modeled as a Multicommodity Flow Problem

European Journal of Operational Research, 2017

A fix-and-optimize heuristic for the high school timetabling problem

Computers & Operations Research, 2014

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The Impact of compactness requirements on the resolution of high school timetabling problem

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Extending an Integer Formulation for the Guillotine 2D Bin Packing Problem

Procedia Computer Science

Service Restoration in Distribution Systems based on Multi-Objective Genetic Algorithm considering repair and switching time

2019 IEEE PES Innovative Smart Grid Technologies Conference - Latin America (ISGT Latin America), 2019

Análise da Viabilidade Técnica de Manobras de Paralelismo entre Alimentadores de Distribuição Utilizando Chaves Monopolares

New adaptive protection algorithm for online overcurrent relay setting in interconnected power systems

Arc-flow approach for single batch-processing machine scheduling

Download

Solid-state light simulator for horticultural applications

2017 Brazilian Power Electronics Conference (COBEP)

Conception and design of a lighting system based on Light Emitting Diodes for spectrum simulation

2016 12th IEEE International Conference on Industry Applications (INDUSCON), 2016

Study of rural administration in Pelotas

A Column Generation Approach to High School Timetabling Modeled as a Multicommodity Flow Problem

by Arton P Dorneles and Olinto Araujo

School timetabling is a classic optimization problem that has been extensively studied due to its... more School timetabling is a classic optimization problem that has been extensively studied due to its practical and theoretical importance. It consists in scheduling a set of class-teacher meetings in a predetermined period of time, satisfying requirements of different types. Given the combinatorial nature of this problem, solving medium and large instances of timetabling to optimality is a challenging task. When resources are tight, often it is difficult to find even a feasible solution. Several techniques have been developed in the literature to tackle the high school timetabling problem. Since the use of exact methods, as mathematical programming techniques, are considered impracticable to solve large real world instances, metaheuristics and hybrid metaheuristics are the most used solution approaches. In this paper we propose a multicommodity flow model for the high school timetabling problem. In addition, we apply Dantzig-Wolfe decomposition to the proposed model, propose a column generation algorithm, and present experimental results on well known instances of the problem. The results show that the lower bounds obtained through our approach are tight and can be generated faster than previous approaches reported in the literature.

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