Papers by Sérgio Fernando Mayerle
Revista Eletrônica em Gestão, Educação e Tecnologia Ambiental, Apr 18, 2022
O conhecimento das atividades, dos processos, bem como do fluxo de insumos, produtos e informaçõe... more O conhecimento das atividades, dos processos, bem como do fluxo de insumos, produtos e informações, pode basear o gerenciamento de um sistema produtivo, ocasionando, assim, vantagens competitivas, redução de custos e previsões de ações futuras. Neste contexto, o presente trabalho tem como objetivo apresentar-fundamentado na literatura e através de enfoques biológico, produtivo, sistêmico e logístico-os processos, as entradas, as saídas, as atividades e os fluxos que fazem parte da produção suinícola, a fim de contribuir para o seu desenvolvimento econômico, social e ambiental. Através de uma visão sistêmica da produção suinícola, verificou-se que a distância entre as granjas e a região fornecedora de ração influencia fortemente aspectos econômicos e ambientais. Assim, granjas localizadas próximas às plantações de grãos apresentam vantagens competitivas. Baseado neste argumento, verificou-se uma tendência migratória da suinocultura brasileira, da região sul para a nova fronteira agrícola MAPITOBA. A fim de mitigar os efeitos negativos ocasionados por esta migração, medidas tecnológicas, administrativas e políticas devem ser tomadas.
UNIVERSIDADE CESUMAR, Oct 23, 2007
RESUMO: Várias são as características favoráveis à evolução da agropecuária brasileira, mas sua t... more RESUMO: Várias são as características favoráveis à evolução da agropecuária brasileira, mas sua taxa de produtividade é reconhecidamente pequena. O objetivo da pesquisa é desenvolver um Sistema de Apoio à Decisão que contemple às incertezas do processo, nos contextos clássico e difuso, trabalhando com séries temporais, programação dinâmica em um ambiente de desenvolvimento Java e banco de dados Firebird. Serão utilizadas técnicas de Pesquisa Operacional. Procura-se o lucro através do método da política de iteração. Espera-se obter uma ferramenta que permita ao empresário ter a mão um sistema de apoio para tomada de decisão no que tange a melhor forma de manter o produto em sua propriedade e a época adequada para o descarte do animal.
Socio-economic Planning Sciences, Oct 1, 2022
Produção
The basic idea introduced in the Economic Order Quantity (EOQ) model is still an important approa... more The basic idea introduced in the Economic Order Quantity (EOQ) model is still an important approach in the study and design of models for inventory management. Recently, some research projects have sought to assess the effects and impacts of these inventory models on supply chain performance. In this context, the paper investigates the consequence of supplier delivery lead-time uncertainty on average inventory held and total cost incurred over a period in a company that uses EOQ rules as replenishment policy. Through computer simulation we compare two inventory control models (herein referred to as Q and P "systematic") using a range of values for the supplier's delivery lead time standard deviation. When lead-time is short or close to optimum replenishment interval systematic Q is found to be better. However, for long delivery lead-time the results of both models are nearly equals. Statistical hypothesis tests are applied in the analyses.
Anais do SPOLM
Page 1. O PROBLEMA DE TRANSPORTES SOB A ÓTICA DOS MODELOS DE EQUILÍBRIO ESPACIAL DE MERCADO Sérgi... more Page 1. O PROBLEMA DE TRANSPORTES SOB A ÓTICA DOS MODELOS DE EQUILÍBRIO ESPACIAL DE MERCADO Sérgio Fernando Mayerle, Dr. UFSC / CTC / EPS - [email protected] - Florianópolis - SC Thiago Dedavid ...
European Journal of Operational Research, 2019
Due to the fast pace of urbanization, governments and water supply service providers have struggl... more Due to the fast pace of urbanization, governments and water supply service providers have struggled to manage the services and the expansion of investments. The operation of Water Distribution Systems (WDS) is often complex, especially when considering the changes in tariffs throughout the day. The cost of energy in these systems can reach 30% of total operating costs and its careful management can represent increased efficiency. The optimization of WDS scheduling operation appears as an effective method to reduce operating costs while ensuring a good service level to the population. In this paper we propose a new linear relaxation for a non-linear integer programming formulation for WDS in order to optimize its operation costs. We test our method on three benchmark instances from the literature improving all solutions from the competing algorithms. We also apply it to a larger new instance obtained from the WDS from the city of Florianópolis, southern Brazil, significantly outperforming the current solution employed by the utility provider. This study makes four main contributions. First, our formulation includes new aspects related to the capacity of storage tanks that were not considered before, which yields a more realistic representation of the physics of water and tanks. Second, our linearization technique includes a variable number of breakpoints, resulting in significantly fewer binary variables for a given error level. Third, our relaxation reduces the search of the space solutions. Lastly, we provide a new real-life instance and improve the solutions for three available benchmark instances.
Revista Científica General José María Córdova, 2017
Para competir en un mercado de constantes cambios, el tiempo constituye un importante diferencial... more Para competir en un mercado de constantes cambios, el tiempo constituye un importante diferencial competitivo para las empresas que consiguen reducir su lead time logístico, que es el tiempo desde la colocación del pedido hasta la entrega del producto al cliente. Ese artículo busca identificar y cuantificar los factores que influyen de modo significativo el lead time logístico de sistemas de producción del sector metal-mecánico. Para esto se realizó una investigación de campo a partir del referente teórico, según el cual los factores que influyen en el lead time fueron estructurados de forma jerárquica, cuantificados por medio de un modelo de regresión y legitimados por un grupo de especialistas y gestores. Los resultados más relevantes fueron: i) el uso de herramientas para la planeación; ii) la reducción del tiempo de entrega de los materiales críticos, y iii) la eliminación de retrabajo.
A two-stage multi-period optimization methodology for aggregate production planning encompassing ... more A two-stage multi-period optimization methodology for aggregate production planning encompassing component supply management and final assembly is developed. This methodology enhances the efficiency of Sales and Operations Planning (S&OP) through a linear programming model that uses cost and profit contribution data to select the optimal product and customer mix. An illustrative application improving the medium-term operations strategy of a Brazilian mechanical manufacturer is presented.
International Journal of Production Economics, 2010
The spreading of fabric onto cutting tables in several layers, and the cutting of this fabric in ... more The spreading of fabric onto cutting tables in several layers, and the cutting of this fabric in the most cost-efficient manner to produce a predetermined number of garments is the apparel manufacturing phase that precedes assembly (sewing) and finishing. The problem consists of determining the lowest cost spreading and cutting schedule for garments of different styles, colors, and sizes, subject to physical constraints of cutting table length and cutting knife height as well as business constraints of required demand for each stock-keeping unit (SKU). The determination of this optimal spreading and cutting schedule for various garment styles is a difficult combinatorial NP-complete optimization problem. This paper proposes the use of an innovative state-space approach using heuristic rules to solve the problem: it is modeled as a least-cost search in a graph where each node represents a different spreading and cutting schedule. Several solution algorithms and heuristics are proposed and tested and an illustrative application to a Brazilian apparel company is presented.
Computers & Operations Research, 2010
This work proposes a network flow linear program model to solve the problem of minimizing costs o... more This work proposes a network flow linear program model to solve the problem of minimizing costs of production and distribution of compound multicommodities. In our proposed model, coupling constraints are considered in order to treat the existing proportionality among several flows of different commodities that are necessary to mixture for composing new commodities. The coupling constraint matrix for this type of problem is very large in general. Our formulation reduces the number of proportionality constraints enabling the use of a solution technique based on a specialization of the primal-dual simplex algorithm applied in two distinct phases. As initial solution it is used a basis built through the heuristic method that allocates flows in low cost lanes. To perform the change of basis operation, the working matrix is stored as a product form of the inverse to keep constant its dimension and to preserve sparsity. Experimental results containing around 200,000 constraints and 75,000 arcs applicable to the distribution of multicommodities of a petrochemical industry were accomplished with success. The results obtained show computer efficiency of the developed algorithm and the applicability of the formulated model.
Inv. Op, 2008
This article is characterized by the presentation of some problems found in ports that emphasize ... more This article is characterized by the presentation of some problems found in ports that emphasize the Berth Allocation Problem, for which a heuristic model has been proposed to resolve this problem. This heuristic proposal is based on Genetic Algorithms and its objective is to allow the learning of this subject, besides urging the reader to implement a computer-based tool that uses these heuristics to solve this problem, practically and efficiently.
Optimization and Engineering, 2016
Available productive capacity is determinant of a company’s success once it allows meeting the cu... more Available productive capacity is determinant of a company’s success once it allows meeting the current and future demand. This article proposes a quantitative model for determining long-term productive capacity in competitive oligopolistic markets, based on the Nash Equilibrium formulated as a Variational Inequality problem. Numerical examples enable an analytical evaluation of the economic equilibrium’s sensitivity to marginal costs, investment costs, hurdle rate, and market saturation. Results show that, in order to achieve a greater market share, it is important to adopt strategies that reduce marginal costs. On the other hand, variations in the hurdle rate may or may not reinforce the position of a competitor in the market and his interest in investing in capacity expansion. Additionally, market saturation may be achieved, beyond which investment becomes unattractive. Each of these is a positive outcome for society, triggering diversified investments and competition in economic sectors where competition is low and profits are high.
International Journal of Production Management and Engineering, 2016
This paper discusses the application of heuristic-based evolutionary technique in search for solu... more This paper discusses the application of heuristic-based evolutionary technique in search for solutions concerning the dynamic job-shop scheduling problems with dependent setup times and alternate routes. With a combinatorial nature, these problems belong to an NP-hard class, with an aggravated condition when in realistic, dynamic and therefore, more complex cases than the traditional static ones. The proposed genetic algorithm executes two important functions: choose the routes using dispatching rules when forming each individual from a defined set of available machines and, also make the scheduling for each of these individuals created. The chromosome codifies a route, or the selected machines, and also an order to process the operations. In essence , each individual needs to be decoded by the scheduler to evaluate its time of completion, so the fitness function of the genetic algorithm, applying the modified Giffler and Thomson’s algorithm, obtains a scheduling of the selected rou...
Transportation Research Part A: Policy and Practice
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Papers by Sérgio Fernando Mayerle