Felipe Martins Müller

A tabu search heuristic for the multiprocessor scheduling problem with sequence dependent setup times

This article deals with the problem of scheduling n jobs on m identical parallel processors with the objective of minimizing the total execution time (makespan). A new three-phase heuristic is proposed for solving this problem. An initial phase constructs a starting solution which is improved, in a second phase, by means of a tabu search method. A final phase follows attempting a further improvement in the current solution. Numerical tests in a series of randomly generated problems indicate that the proposed method outperforms a previous heuristic. Comparisons with an exact procedure attest that our method produces good-quality solutions in reasonable running times.

A composite heuristic for the identical parallel machine scheduling problem with minimum makespan objective

This paper describes a new heuristic algorithm for the problem of scheduling n independent jobs on m identical parallel machines in order to minimize the makespan. The algorithm produces near-optimal solutions in short computation times. It outperforms alternative heuristics on a series of test problems.

Comparing meta-heuristic approaches for parallel machine scheduling problems

The aim of this paper is to compare the performance of two meta-heuristic methods proposed to solve the identical parallel machine scheduling problem with sequence dependent setup times. The goal is to minimize the makespan. The first algorithm is a tabu search based heuristic and the second a memetic approach, which combines a population-based method with local search procedures. As benchmarks for small-sized instances, optimal and lower bound values are used provided by a dichotomous search. For larger instances, the comparisons rely on the best known solutions provided by an exhaustive search variant of the tabu procedure.

The m-Traveling Salesman Problem with Minmax Objective

This article considers the minmax version of the m-Traveling Salesman Problem in which the objective is to minimize the length of the longest route. Tabu search heuristics and exact search schemes are developed. Problems involving up to 50 vertices are solved to optimality. (A)

Matheuristics for the capacitated p‐median problem

The improvement in the performance of computers and mathematical programming techniques has led to the development of a new class of algorithms called matheuristics. Associated with an improvement of Mixed Integer Programming (MIP) solvers, these methods have successfully solved plenty of combinatorial optimization problems. This paper presents a matheuristic approach that hybridizes local search based metaheuristics and mathematical programming techniques to solve the capacitated p-median problem. The proposal considers reduced mathematical models obtained by a heuristic elimination of variables that are unlikely to belong to a good or optimal solution. In addition, a partial optimization algorithm based on the reduction is proposed. All mathematical models are solved by an MIP solver. Computational experiments on five sets of instances confirm the good performance of our approach.

Ant Colony Optimization With Local Search for Dynamic Traveling Salesman Problems

For a dynamic traveling salesman problem (DTSP), the weights (or traveling times) between two cities (or nodes) may be subject to changes. Ant colony optimization (ACO) algorithms have proved to be powerful methods to tackle such problems due to their adaptation capabilities. It has been shown that the integration of local search operators can significantly improve the performance of ACO. In this paper, a memetic ACO algorithm, where a local search operator (called unstring and string) is integrated into ACO, is proposed to address DTSPs. The best solution from ACO is passed to the local search operator, which removes and inserts cities in such a way that improves the solution quality. The proposed memetic ACO algorithm is designed to address both symmetric and asymmetric DTSPs. The experimental results show the efficiency of the proposed memetic algorithm for addressing DTSPs in comparison with other state-of-the-art algorithms.

An Ant Colony Optimization Based Memetic Algorithm for the Dynamic Travelling Salesman Problem

Ant colony optimization (ACO) algorithms have proved to be able to adapt for solving dynamic optimization problems (DOPs). The integration of local search algorithms has also proved to significantly improve the output of ACO algorithms. However, almost all previous works consider stationary environments. In this paper, the MAX -MIN Ant System, one of the best ACO variations, is integrated with the unstringing and stringing (US) local search operator for the dynamic travelling salesman problem (DTSP). The best solution constructed by ACO is passed to the US operator for local search improvements. The proposed memetic algorithm aims to combine the adaptation capabilities of ACO for DOPs and the superior performance of the US operator on the static travelling salesman problem in order to tackle the DTSP. The experiments show that the MAX -MIN Ant System is able to provide good initial solutions to US and the proposed algorithm outperforms other peer ACO-based memetic algorithms on different DTSPs.

Exact Algorithms for the Imbalanced Time Minimizing Assignment Problem

This paper studies the imbalanced time minimizing assignment problem (ITMAP) dealing with the allocation of n jobs to m (< n) machines. There are few works about this problem in the literature. In fact, only one lexi-shearch algorithm was found for the ITMAP, but it contain an slight error that was corrected here. Other algorithm by dynamic programming was found for the R∣Cmax problem and adapted for the ITMAP. A new approach through a linear model for this problem is introduced in this paper achieving considerables better results.

Abordagem de Apoio ao Ensino e Aprendizagem de Teste de Software Baseada em Jogos Sérios e Mundos Virtuais

A educacao a distancia tem ganhado significativa atencao tanto na academia quanto nas iniciativas governamentais. Neste contexto, cresce tambem a preocupacao com a avaliacao da qualidade dos diversos aspectos destes cursos mediados pelas tecnologias da informacao e comunicacao. Apesar de muitos trabalhos discutirem diversos aspectos da avaliacao em Ead, a literatura carece de relatos de experiencia que, especialmente, abordem os cursos tecnicos a distancia que possuem especificidades relevantes. Assim, este trabalho relata uma experiencia onde se avalia e adapta uma das propostas existentes na literatura de avaliacao mediada por foruns, ao contexto dos cursos tecnicos a distancia, constituindo-se esta adaptacao e sua discussao as principais contribuicoes do mesmo.Em Educacao a Distância mediada por meio de Ambientes Virtuais de Aprendizagem, foruns de discussao sao um instrumento importante e amplamente utilizado na articulacao de debates e discussoes entre os atores envolvidos no processo de ensino e aprendizagem. Com a ampla utilizacao dos foruns muitas mensagens sao trocadas e isso, por vezes, excede a capacidade de monitoramento por parte dos professores e tutores. O presente trabalho apresenta a concepcao de um classificador de mensagens de foruns que classifica as mensagens em positivas ou negativas, a fim de identificar mensagens que necessitam de maior atencao. Este trabalho aplica conceitos de mineracao de textos, com o algoritmo SVM obtendo taxas de acerto satisfatorias.Este artigo apresenta o framework Contagious, cujo proposito e estabelecer diretrizes que norteiem a construcao de redes sociais online orientadas a Difusao de Inovacoes. Compreendo-se o fenomeno das redes sociais online como consequencia natural do carater social do ser humano, vislumbrou-se esse meio tecnologico de comunicacao e interacao social como potencial ferramenta para a extensao de praticas educativas, com vistas a formacao do carater integral do cidadao. Para isso, foi adotada a teoria de Difusao de Inovacoes, propria das ciencias sociais. As contribuicoes deste trabalho, portanto, compreendem duas vertentes: a) o mapeamento de principios de uma teoria social na forma de recursos computacionais e; b) um enfoque orientado a educacao sobre as redes sociais online.A proposta do trabalho consiste em desenvolver um sistema para ser usado no celular como ferramenta de auxilio para alfabetizacao, utilizando-se de imagens e sons como forma de facilitar o aprendizado. Como metodo de desenvolvimento utiliza-se o processo P@PSEduc (Processo Agil para Software Educativo) e a ferramenta JME (Java Micro Edition).O crescente uso e difusao de tecnologias Web, a ubiquidade de ferramentas educacionais vem proporcionado verdadeiras revolucoes nos ambientes de ensino. Atualmente, sabe-se que nao mais se deve tratar alunos de forma homogenea, como se assim os fossem. Em face disso, este artigo apresenta um sistema adaptativo de apoio a aprendizagem colaborativa, cujo tema e a construcao e representacao do conhecimento por meio de mapas mentais multimidia. Tal sistema, baseia-se na Teoria da Carga Cognitiva, cuja preocupacao primaria e a facilidade com a qual as informacoes sao processadas pelos individuos.

Ensino-aprendizagem colaborativo mediado pelo Wiki do Moodle

Through the wiki Moodle, we developed distance education activities in the Physics Course at UFSM, aiming at producing a hypermedia school subject related to the discipline Physics 2 structuring teaching theme: Heat, Environment and uses of Energy (coming from the PCN+), placing the problematic dialogue in the transversal theme “Environment”. We designed