Abstract Forecasting is one of the fundamental inputs to support planning decisions in retail cha... more Abstract Forecasting is one of the fundamental inputs to support planning decisions in retail chains. Frequently, forecasting systems in retail are based on Gaussian models, which may be highly unrealistic when considering daily retail data. In addition, the majority of these systems rely on point forecasts, limiting their practical use in retailing decisions, which often requires the full predictive density for decision making. The main contribution of this paper is the modeling of daily distribution centers (DCs) level aggregate demand forecasting using a recently proposed framework for non-Gaussian time series called score-driven models or Generalized Autoregressive Score (GAS) models. An experimental study was carried out using real data from a large retail chain in Brazil. A log-normal GAS model is compared to usual benchmarks, namely neural networks, linear regression, and exponential smoothing. The results show the GAS model is a competitive alternative to retail demand forecasting in daily frequency, with the advantage of producing a closed form predictive density by construction.
Anais do I Simpósio Brasileiro de Sistemas de Informação (SBSI 2004), 2004
O artigo apresenta um sistema de apoio à decisão aplicado ao planejamento operacional da coleta s... more O artigo apresenta um sistema de apoio à decisão aplicado ao planejamento operacional da coleta seletiva de resíduos sólidos (SCOLDSS), o qual tem por funcionalidade principal à geração de alternativas ao processo decisório no que se refere á: (a) alocação de veiculos para a roleta seletiva, bem como o roteiro a ser percorrido pelos mesmos e, (b} a determinação da quantidade diária de resíduos sólidos a ser enviado a cada unidade de triagem. Para o desenvolvimento do mesmo foi utilizada a combinação de técnicas advindas da Pesquisa Operacional, que são a simulação computacional de eventos discretos e algoritmos para o problema da alocação e roteamento de veículos. O sistema foi desenvolvido utilizando o ambiente Borland Delphi e, para a simulação foi utilizado o simulador Arena 3.5. Para a validação do SCOLDSS estão sendo utilizados dados da coleta seletiva de um município do Rio Grande do Sul.
Este trabalho de pesquisa tem como objetivo desenvolver uma modelagem de Sistemas Flexíveis de Ma... more Este trabalho de pesquisa tem como objetivo desenvolver uma modelagem de Sistemas Flexíveis de Manufatura (FMS), fornecendo a administradores e engenheiros uma ferramenta objetiva de análise a ser utilizada durante o projeto e operação destes sistemas. Essa ferramenta é um modelo genérico de simulação computacional capaz de replicar, em laboratório, os fenômenos que ocorrem no interior de sistemas discretos de produção'em lotes. Desta forma, permite a esses profissionais que conheçam e questionem os mesmos, reduzindo os riscos e incertezas inerentes ao processo de implementação prática. O trabalho apresenta uma discussão do conceito de FMS, explicitando a necessidade de uma ferramenta de análise, bem como uma descrição completa do modelo abstrato desenvolvido e de sua representação computacional, denominada de SIMFLEX.The aim of this reseach is to model a Flexible Manufacturing Systems(FMS), offering to managers and engineers an objective tool of analysis to be used during the design and operation of these systems. The tool is a computational simulation model that emulates, in laboratory, the events presented in batch production systems. It allows a better knowledge and inquiring of these systems by these professionals, decreasing'risks and uncertanties inherent in theirs implementation process. The work presents a discussion of the FMS concept, emphasizing the need of a simulation tool such as this. A complete description of the abstract model developed and its computational representation, called SIMFLEX, is also presented
This paper presents the conception, modeling, and implementation of a decision support system app... more This paper presents the conception, modeling, and implementation of a decision support system applied to the operational planning of solid waste collection systems, called SCOLDSS. The main functionality of the system is the generation of alternatives to the decision processes concerning: (a) the allocation of separate collection vehicles, as well as the determination of their routes, and (b) the determination
This study presents the conception, modeling, and implementation of a decision support system app... more This study presents the conception, modeling, and implementation of a decision support system applied to the operational planning of solid waste collection systems, called SCOLDSS. The main functionality of the system is the generation of alternatives to the decision processes concerning: (a) the allocation of separate collection vehicles, as well as the determination of their routes and (b) the determination of the daily amount of solid waste to be sent to each sorting unit, in order to avoid waste of labor force and to reduce the amount of waste sent to the landfills. To develop the computer system, a combination of quantitative techniques was used, such as: simulation of discrete events and algorithms/heuristics for vehicle allocation and routing. The system was developed using the Borland Delphi environment and the commercial software Arena to carry out the simulations. We also present a computational study with real-life data from the solid waste collection in Porto Alegre, Brazil, in which we show that the results provided by the computational system outperform the operation planning currently adopted.
When a vehicle on a scheduled trip breaks down, one or more vehicles need to be rescheduled to se... more When a vehicle on a scheduled trip breaks down, one or more vehicles need to be rescheduled to serve the customers on that trip with minimum operating and delay costs. The problem of reassigning vehicles in real‐time to this cut trip as well as to other scheduled trips with given starting and ending times, is referred to as the vehicle rescheduling problem (VRSP). This paper considers modeling, algorithmic, and computational aspects of the single‐depot VRSP. The paper formulates a model for this problem and develops several fast algorithms to solve it, including parallel synchronous auction algorithms. The concept of the common feasible network (CFN) is introduced to find a good set of initial “prices” for speeding up the auction algorithm. Computational experiments on randomly generated problems are described. Computational results show that, for small problems, all of the developed algorithms demonstrate very good computational performances. For large problems, parallel CFN‐based ...
Abstract Forecasting is one of the fundamental inputs to support planning decisions in retail cha... more Abstract Forecasting is one of the fundamental inputs to support planning decisions in retail chains. Frequently, forecasting systems in retail are based on Gaussian models, which may be highly unrealistic when considering daily retail data. In addition, the majority of these systems rely on point forecasts, limiting their practical use in retailing decisions, which often requires the full predictive density for decision making. The main contribution of this paper is the modeling of daily distribution centers (DCs) level aggregate demand forecasting using a recently proposed framework for non-Gaussian time series called score-driven models or Generalized Autoregressive Score (GAS) models. An experimental study was carried out using real data from a large retail chain in Brazil. A log-normal GAS model is compared to usual benchmarks, namely neural networks, linear regression, and exponential smoothing. The results show the GAS model is a competitive alternative to retail demand forecasting in daily frequency, with the advantage of producing a closed form predictive density by construction.
Anais do I Simpósio Brasileiro de Sistemas de Informação (SBSI 2004), 2004
O artigo apresenta um sistema de apoio à decisão aplicado ao planejamento operacional da coleta s... more O artigo apresenta um sistema de apoio à decisão aplicado ao planejamento operacional da coleta seletiva de resíduos sólidos (SCOLDSS), o qual tem por funcionalidade principal à geração de alternativas ao processo decisório no que se refere á: (a) alocação de veiculos para a roleta seletiva, bem como o roteiro a ser percorrido pelos mesmos e, (b} a determinação da quantidade diária de resíduos sólidos a ser enviado a cada unidade de triagem. Para o desenvolvimento do mesmo foi utilizada a combinação de técnicas advindas da Pesquisa Operacional, que são a simulação computacional de eventos discretos e algoritmos para o problema da alocação e roteamento de veículos. O sistema foi desenvolvido utilizando o ambiente Borland Delphi e, para a simulação foi utilizado o simulador Arena 3.5. Para a validação do SCOLDSS estão sendo utilizados dados da coleta seletiva de um município do Rio Grande do Sul.
Este trabalho de pesquisa tem como objetivo desenvolver uma modelagem de Sistemas Flexíveis de Ma... more Este trabalho de pesquisa tem como objetivo desenvolver uma modelagem de Sistemas Flexíveis de Manufatura (FMS), fornecendo a administradores e engenheiros uma ferramenta objetiva de análise a ser utilizada durante o projeto e operação destes sistemas. Essa ferramenta é um modelo genérico de simulação computacional capaz de replicar, em laboratório, os fenômenos que ocorrem no interior de sistemas discretos de produção'em lotes. Desta forma, permite a esses profissionais que conheçam e questionem os mesmos, reduzindo os riscos e incertezas inerentes ao processo de implementação prática. O trabalho apresenta uma discussão do conceito de FMS, explicitando a necessidade de uma ferramenta de análise, bem como uma descrição completa do modelo abstrato desenvolvido e de sua representação computacional, denominada de SIMFLEX.The aim of this reseach is to model a Flexible Manufacturing Systems(FMS), offering to managers and engineers an objective tool of analysis to be used during the design and operation of these systems. The tool is a computational simulation model that emulates, in laboratory, the events presented in batch production systems. It allows a better knowledge and inquiring of these systems by these professionals, decreasing'risks and uncertanties inherent in theirs implementation process. The work presents a discussion of the FMS concept, emphasizing the need of a simulation tool such as this. A complete description of the abstract model developed and its computational representation, called SIMFLEX, is also presented
This paper presents the conception, modeling, and implementation of a decision support system app... more This paper presents the conception, modeling, and implementation of a decision support system applied to the operational planning of solid waste collection systems, called SCOLDSS. The main functionality of the system is the generation of alternatives to the decision processes concerning: (a) the allocation of separate collection vehicles, as well as the determination of their routes, and (b) the determination
This study presents the conception, modeling, and implementation of a decision support system app... more This study presents the conception, modeling, and implementation of a decision support system applied to the operational planning of solid waste collection systems, called SCOLDSS. The main functionality of the system is the generation of alternatives to the decision processes concerning: (a) the allocation of separate collection vehicles, as well as the determination of their routes and (b) the determination of the daily amount of solid waste to be sent to each sorting unit, in order to avoid waste of labor force and to reduce the amount of waste sent to the landfills. To develop the computer system, a combination of quantitative techniques was used, such as: simulation of discrete events and algorithms/heuristics for vehicle allocation and routing. The system was developed using the Borland Delphi environment and the commercial software Arena to carry out the simulations. We also present a computational study with real-life data from the solid waste collection in Porto Alegre, Brazil, in which we show that the results provided by the computational system outperform the operation planning currently adopted.
When a vehicle on a scheduled trip breaks down, one or more vehicles need to be rescheduled to se... more When a vehicle on a scheduled trip breaks down, one or more vehicles need to be rescheduled to serve the customers on that trip with minimum operating and delay costs. The problem of reassigning vehicles in real‐time to this cut trip as well as to other scheduled trips with given starting and ending times, is referred to as the vehicle rescheduling problem (VRSP). This paper considers modeling, algorithmic, and computational aspects of the single‐depot VRSP. The paper formulates a model for this problem and develops several fast algorithms to solve it, including parallel synchronous auction algorithms. The concept of the common feasible network (CFN) is introduced to find a good set of initial “prices” for speeding up the auction algorithm. Computational experiments on randomly generated problems are described. Computational results show that, for small problems, all of the developed algorithms demonstrate very good computational performances. For large problems, parallel CFN‐based ...
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Papers by Denis Borenstein