Luciano Ferreira

A fuzzy-Bayesian model for supplier selection

The selection supplier problem has received a lot of attention from academics in recent years. Several models were developed in the literature, combining consolidated operations research and artificial intelligence methods and techniques. However, the tools presented in the literature neglected learning and adaptation, since this decision making process is approached as a static one rather than a highly dynamic process. Delays, lack of capacity, quality related issues are common examples of dynamic aspects that have a direct impact on long-term relationships with suppliers. This paper presents a novel method based on the integration of influence diagram and fuzzy logic to rank and evaluate suppliers. The model was developed to support managers in exploring the strengths and weaknesses of each alternative, to assist the setting of priorities between conflicting criteria, to study the sensitivity of the behavior of alternatives to changes in underlying decision situations, and finally to identify a preferred course of action. To be effective, the computational implementation of the method was embedded into an information system that includes several functionalities such as supply chain simulation and suppliers databases. A case study in the biodiesel supply chain illustrates the effectiveness of the developed method.

Normative agent-based simulation for supply chain planning

This paper presents an agent-based simulation framework for supply chain (SC) planning, introducing the notion of normative agent. The analysis of the relevant literature shows that most research works carried out in this area aim to handle specific problems and contexts. Although some methodologies and more generic solutions have been proposed, they are not able to cope with SCs in which regulation plays an important role, whether issued by a government agent or by an international institution. Several SCs, such as in the energy, food, chemical, and forestry areas, are highly regulated. Explicitly modelling the actors involved in the regulation of SCs using normative agents allowed us to evaluate the potential benefits of alternative strategies for planning of regulated SCs. The modelling of a biodiesel SC is presented as a case study.

Hybrid fuzzy MADM ranking procedure for better alternative discrimination

In this paper, we propose a hybrid fuzzy decision making approach, combining elements of fuzzy-ELECTRE and Fuzzy-TOPSIS, towards a new ranking procedure. The main objective of FETOPSIS is to offer rankings with good alternative discriminatory power to decision makers (DMs). This research work was motivated by a real case study in which multiple attribute decision making techniques were used to select the best set of investment projects for the industrial restructuring of a small oil company in Brazil. After the application of Fuzzy-TOPSIS and ELECTRE II, the obtained rankings were quite deceptive from the DMs point of view, either to very close scores or by the excess of indifferences among alternatives. Our developed approach uses the closeness coefficients to rank the alternatives, following Fuzzy-TOPSIS, however they are computed over the normalized fuzzy concordance and discordance indexes based on the ELECTRE family. Extensive computational experiments were performed to evaluate our method. The good results obtained by FETOPSIS in the experiments, both in terms of alternative discriminatory power of rankings, and eliminating ranking reversal cases, gave us the confidence to apply the method in the real case. The DMs praised the developed approach, since the obtained rankings were more discriminatory in the alternatives than both Fuzzy-TOPSIS and ELECTRE II, making it possible to select with confidence a set of suited alternatives. HighlightsA new MADM approach, combining ELECTRE and TOPSIS elements, was introduced.We addressed the gap in the ELECTRE literature about ranking reversals.We performed an in-depth analysis of an ELECTRE based method.The developed approach improved the discrimination of alternatives.Preferred scores by DMs were obtained in a real-world application.

Enhancing the Discrimination of Alternatives in Fuzzy-TOPSIS

Fuzzy-TOPSIS is one of the most widely applied methods for solving multi-attribute decision making problems. However, an analysis of academic and real-life applications of this method has pointed out that the final alternative scores are very close, with little dispersion among them, making it difficult for the decision makers’ to choice/ranking the alternatives. The main objective of this paper is to enhance the ability of Fuzzy-TOPSIS to discriminate alternatives, making it easy for a decision maker to select or ranking alternatives. To achieve this, we redefined the computation of the positive and negative ideal solution of the classical TOPSIS method as a combination of the fuzzy concordance and discordance indexes from Fuzzy-ELECTRE. The proposed model was validated in a real case study, and further compared with Fuzzy-ELECTRE, using simulation experiments, and Fuzzy-TOPSIS, using results from four recent papers published in the literature. The results obtained show that the proposed method improved the ranking and sorting of the alternatives for all analyzed cases, considering ranking dispersion, global interval range of the scores, and the difference between the first and second best alternatives. The main justification for this behavior is the partial non-compensatory nature of our method, introduced by incorporating some ELECTRE’s elements into Fuzzy-TOPSIS.

Student selection in a Brazilian university: using a multi-criteria method

Student selection is a complex decision-making process, in which several criteria need to be considered simultaneously. In this paper, we address this problem for a Brazilian university that has created an interdisciplinary degree in which several intermediate selection processes are required during the course, defining the final title degree. The university is currently using an aggregated score based on the performance of a student in the course. However, this method is facing difficulties in selecting the best students, because deficiencies in the way transferred, dropped and quit course credits are accounted for. As a possible alternative for the current method, we developed a hybrid ranking algorithm, called ELECTRE–TOPSIS (E–T). This method combines elements of the ELECTRE family and TOPSIS, two well-known multi-attribute analysis tools, to rank students based on objective criteria. Computational experiments and a case study were conducted to evaluate E–T. The results show that our approach provides quite competitive rankings in comparison with similar methods, through simultaneously eliminating ranking reversal and better balancing the formation time and the academic performance of the evaluated students.

UM MODELO DE SIMULAÇÃO PARA GESTÃO DA CAPACIDADE DOS AEROPORTOS BRASILEIROS

2 Um modelo de simulação para gestão da capacidade dos aeroportos brasileiros REAd | Porto Alegre – Edição 80 N° 1 – janeiro/abril 2015 – p. 1-26 The importance of air transportation to the development of a country and the growth of the Brazilian airline industry imply the need for an efficient management of the airports, aiming to balance the passenger demand and the capacity of the system. Thus, this paper presents a System Dynamics model in order to assist airport management to evaluate the size of the subsystems of an airport, such as Passenger Terminals, Runways, and Patios. Using data on air passenger demand, average number of passengers per flight, peak-hour demand, service level of the passenger terminal, and average time in the patio, this paper analyzes the situation of the thirteen Brazilian airports. Finally, by comparing the simulation data with the installed capacity, this paper classifies the situation of each subsystem of the airports studied into three categories: adequate, worrying, and critical. Among the main results obtained, we can highlight different factors, such as the subsystem that presents the best condition (the Runway), while the Passenger Terminal is the one in the worst condition. The investments and the capacity increases are insufficient to meet the passenger demand in the peak-hour with an annual growth rate of 5%.A importância do setor aereo para o desenvolvimento de um pais e o crescimento da demanda aerea brasileira implica na necessidade de uma gestao eficiente dos aeroportos, buscando o equilibrio entre a capacidade e a demanda aerea. Diante disso, este artigo apresenta um modelo em Dinâmica de Sistemas capaz de auxiliar a gestao aeroportuaria brasileira em relacao ao dimensionamento dos subsistemas de um aeroporto (Terminal de Passageiros, Pistas e Patio). O modelo utiliza dados sobre demanda aerea de passageiros, numero medio de passageiros por voo, demanda hora-pico, nivel de servico do terminal de passageiros e tempo medio de estacionamento das aeronaves para analisar a situacao de treze aeroportos brasileiros. Por fim, atraves da comparacao da capacidade ideal produzida pelo modelo de simulacao com a capacidade real instalada, o artigo classifica a situacao de cada um dos subsistemas dos aeroportos estudos em adequada, critica e preocupante. Entre os principais resultados obtidos pode-se destacar que: a Pista e o subsistemas que apresenta melhores condicoes, enquanto que o terminal de passageiros e o subsistema em pior condicao; os investimentos e aumento da capacidade sao insuficientes para atender uma demanda de crescimento a 5% ao ano na hora-pico.

A simulation model for capacity management of the brazilian airports

2 Um modelo de simulação para gestão da capacidade dos aeroportos brasileiros REAd | Porto Alegre – Edição 80 N° 1 – janeiro/abril 2015 – p. 1-26 The importance of air transportation to the development of a country and the growth of the Brazilian airline industry imply the need for an efficient management of the airports, aiming to balance the passenger demand and the capacity of the system. Thus, this paper presents a System Dynamics model in order to assist airport management to evaluate the size of the subsystems of an airport, such as Passenger Terminals, Runways, and Patios. Using data on air passenger demand, average number of passengers per flight, peak-hour demand, service level of the passenger terminal, and average time in the patio, this paper analyzes the situation of the thirteen Brazilian airports. Finally, by comparing the simulation data with the installed capacity, this paper classifies the situation of each subsystem of the airports studied into three categories: adequate, worrying, and critical. Among the main results obtained, we can highlight different factors, such as the subsystem that presents the best condition (the Runway), while the Passenger Terminal is the one in the worst condition. The investments and the capacity increases are insufficient to meet the passenger demand in the peak-hour with an annual growth rate of 5%.A importância do setor aereo para o desenvolvimento de um pais e o crescimento da demanda aerea brasileira implica na necessidade de uma gestao eficiente dos aeroportos, buscando o equilibrio entre a capacidade e a demanda aerea. Diante disso, este artigo apresenta um modelo em Dinâmica de Sistemas capaz de auxiliar a gestao aeroportuaria brasileira em relacao ao dimensionamento dos subsistemas de um aeroporto (Terminal de Passageiros, Pistas e Patio). O modelo utiliza dados sobre demanda aerea de passageiros, numero medio de passageiros por voo, demanda hora-pico, nivel de servico do terminal de passageiros e tempo medio de estacionamento das aeronaves para analisar a situacao de treze aeroportos brasileiros. Por fim, atraves da comparacao da capacidade ideal produzida pelo modelo de simulacao com a capacidade real instalada, o artigo classifica a situacao de cada um dos subsistemas dos aeroportos estudos em adequada, critica e preocupante. Entre os principais resultados obtidos pode-se destacar que: a Pista e o subsistemas que apresenta melhores condicoes, enquanto que o terminal de passageiros e o subsistema em pior condicao; os investimentos e aumento da capacidade sao insuficientes para atender uma demanda de crescimento a 5% ao ano na hora-pico.

Un modelo de simulación para la gestión de la capacidad de aeropuertos brasileños

2 Um modelo de simulação para gestão da capacidade dos aeroportos brasileiros REAd | Porto Alegre – Edição 80 N° 1 – janeiro/abril 2015 – p. 1-26 The importance of air transportation to the development of a country and the growth of the Brazilian airline industry imply the need for an efficient management of the airports, aiming to balance the passenger demand and the capacity of the system. Thus, this paper presents a System Dynamics model in order to assist airport management to evaluate the size of the subsystems of an airport, such as Passenger Terminals, Runways, and Patios. Using data on air passenger demand, average number of passengers per flight, peak-hour demand, service level of the passenger terminal, and average time in the patio, this paper analyzes the situation of the thirteen Brazilian airports. Finally, by comparing the simulation data with the installed capacity, this paper classifies the situation of each subsystem of the airports studied into three categories: adequate, worrying, and critical. Among the main results obtained, we can highlight different factors, such as the subsystem that presents the best condition (the Runway), while the Passenger Terminal is the one in the worst condition. The investments and the capacity increases are insufficient to meet the passenger demand in the peak-hour with an annual growth rate of 5%.A importância do setor aereo para o desenvolvimento de um pais e o crescimento da demanda aerea brasileira implica na necessidade de uma gestao eficiente dos aeroportos, buscando o equilibrio entre a capacidade e a demanda aerea. Diante disso, este artigo apresenta um modelo em Dinâmica de Sistemas capaz de auxiliar a gestao aeroportuaria brasileira em relacao ao dimensionamento dos subsistemas de um aeroporto (Terminal de Passageiros, Pistas e Patio). O modelo utiliza dados sobre demanda aerea de passageiros, numero medio de passageiros por voo, demanda hora-pico, nivel de servico do terminal de passageiros e tempo medio de estacionamento das aeronaves para analisar a situacao de treze aeroportos brasileiros. Por fim, atraves da comparacao da capacidade ideal produzida pelo modelo de simulacao com a capacidade real instalada, o artigo classifica a situacao de cada um dos subsistemas dos aeroportos estudos em adequada, critica e preocupante. Entre os principais resultados obtidos pode-se destacar que: a Pista e o subsistemas que apresenta melhores condicoes, enquanto que o terminal de passageiros e o subsistema em pior condicao; os investimentos e aumento da capacidade sao insuficientes para atender uma demanda de crescimento a 5% ao ano na hora-pico.