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- A warehouse design decision model: case studyPublication . Geraldes, Carla A.S.; Carvalho, Maria do Sameiro; Pereira, GuilhermeToday’s competitive and volatile market requires flexibility, quality and efficiency from the logistics operations. In this context, warehouses are an important link of the logistic chain and warehouse management plays an important role over customer's service. Throughout this work we analyze a mathematical model aiming to support warehouse management decisions. A case study is used for that purpose and the model jointly identifies product allocation to the functional areas in the warehouse, as well as the size of each area. This case study also evaluates the performance of the model when real data is used. Model is solved using LINGO 9.0 mixed-integer commercial solver, and potential savings achieved using the proposed technique are discussed.
- Analysis of a bakery production system using discrete simulationPublication . Geraldes, Carla A.S.; Setti, Fabiane K.; Almeida, João P.The main objective of this study is to analyse different production scenarios of a company, and propose improvements with the use of discrete event simulation. We use a simulation tool, SIMIO software, to reproduce the existing production layout of the company. Our purpose is to gather relevant information about the actual production system behaviour, and to find strategies to increase the production level to meet the market demand. Based on initial simulation model, some production scenarios were developed involving the production of different products. The analysis of the developed models highlighted the need for improvements. Among the obtained results, the creation of different mixed production scenarios allowed to increase the production level while maintaining the current existing resources. The results of this work can be easily implemented in the company in order to increase the production level without increasing costs since they do not involve the purchase of new equipment. In conclusion, this study highlighted the ability of the simulation technique to analyse manufacturing processes throughout the creation of different scenarios providing insights on the production process improving the companies’ productive performance
- Concepção e planeamento de armazénsPublication . Geraldes, Carla A.S.; Carvalho, Sameiro; Pereira, GuilhermeUma cadeia de abastecimento pode ser considerada como uma rede de entidades individuais que, colectivamente são responsáveis pela gestão de fluxos de materiais e de informação desde os fornecedores até ao consumidor final. Assim, a eficiência e eficácia destas redes é fortemente condicionada pelas operações em cada uma das entidades que a integram. Neste sentido, os armazéns proporcionam uma importante ligação entre fornecedores, distribuidores e consumidores pelo que podem ser considerados uma entidade essencial na gestão da cadeia de abastecimento. A concepção e planeamento de um armazém envolve decisões complexas para as quais são diminutas ferramentas de apoio às decisões envolvidas. A complexidade das decisões envolvidas inclui: enorme quantidade de informação a ser processada; elevado número de possíveis alternativas; a existência de vários objectivos que por vezes são conflituosos bem como a incerteza associada ao fluxo de materiais dentro e fora do armazém. São diminutos os modelos de apoio à decisão que integrem várias decisões envolvidas na concepção e planeamento de armazéns. Esta escassez de modelos integradores que traduzam a complexidade destes sistemas é devida à dificuldade de análise e ao complexo tratamento analítico que lhes é inerente. Nesta comunicação será discutido um modelo que integra algumas das decisões envolvidas na concepção e planeamento de armazéns tais como: gestão de inventários, a atribuição de produtos a diferentes zonas de armazenagem e a alocação dos produtos dentro das áreas de armazenamento. O objectivo é mostrar as potencialidades e as fraquezas do modelo quando aplicado a uma variedade de problemas bem como identificar novas oportunidades de investigação.
- An optimisation model for the warehouse design and product assignment and allocation problemPublication . Geraldes, Carla A.S.; Carvalho, Sameiro; Pereira, GuilhermeWarehouse design and planning is a great challenge in the field of Supply Chain Management. In this paper we discuss an optimisation model aiming to support some warehouse management decisions. In particular a mixed-integer programming model (MILP) is presented to determine product assignment and allocation to the functional areas, as well as the size of each area. Our aim is to capture the trade-offs among the different warehouse costs in order to achieve global optimal design satisfying throughput requirements.
- IO2021 analytics for a better world: livro de resumosPublication . Moniz, Samuel (Ed.); Lopes, Isabel Cristina (Ed.); Geraldes, Carla A.S. (Ed.); Carravilla, Maria Antónia (Ed.); Póvoa, Ana Paula Barbosa (Ed.); Oliveira, José F. (Ed.)
- Operational research models in warehouse design and planningPublication . Geraldes, Carla A.S.; Carvalho, Sameiro; Pereira, GuilhermeThe design and operation of a warehouse involve many challenging decision problems. In this paper, a literature review on warehousing models is presented. Authors start with a hierarchy of decision problems encountered in setting up warehouse design and planning processes. Next, some operational research decision models and solution algorithms supporting decision making at each discussed level are presented. The aim is to link academic researchers and warehouse practitioners, explaining what planning models and methods are currently available for warehouse design and planning, and what are the future research opportunities.
- An optimisation model for the warehouse design and planning problemPublication . Geraldes, Carla A.S.; Carvalho, Sameiro; Pereira, GuilhermeIn spite of the importance of warehouses in the field of the supply chain management, there is not a single decision model that integrates all the decisions that concerns the warehouse design and planning problem. In this paper we discuss a mathematical programming model aiming to support some warehouse management and inventory decisions. Our aim is to address the complexity related to the modeling of the warehouse design and planning problem. In particular an optimisation model is presented to capture the trade-offs among both inventory and warehouse costs in order to achieve global optimal design satisfying throughput requirements.
- Operational research IO 2021—analytics for a better world. XXI Congress of APDIO, Figueira da Foz, Portugal, November 7–8, 2021Publication . Almeida, João P. (Ed.); Geraldes, Carla A.S. (Ed.); Lopes, Isabel Cristina (Ed.); Moniz, Samuel (Ed.); Oliveira, José F. (Ed.); Pinto, Alberto A. (Ed.)This book provides the current status of research on the application of OR methods to solve emerging and relevant operations management problems. Each chapter is a selected contribution of the IO2021 - XXI Congress of APDIO, the Portuguese Association of Operational Research, held in Figueira da Foz from 7 to 8 November 2021. Under the theme of analytics for a better world, the book presents interesting results and applications of OR cutting-edge methods and techniques to various real-world problems. Of particular importance are works applying nonlinear, multi-objective optimization, hybrid heuristics, multicriteria decision analysis, data envelopment analysis, simulation, clustering techniques and decision support systems, in different areas such as supply chain management, production planning and scheduling, logistics, energy, telecommunications, finance and health. All chapters were carefully reviewed by the members of the scientific program committee.
- XVI Congresso da Associação Portuguesa de Investigação Operacional: livro de resumosPublication . Oliveira, José F. (Ed.); Vaz, Clara B. (Ed.); Pereira, Ana I. (Ed.); Geraldes, Carla A.S. (Ed.)
- Modelos de PL aplicados à gestão das operações de um armazémPublication . Geraldes, Carla A.S.; Carvalho, Sameiro; Pereira, GuilhermeO mercado global está cada vez mais competitivo e mais volátil, exigindo flexibilidade, qualidade e eficiência nas operações logísticas. Os armazéns são, inevitavelmente, elos importantes da cadeia logística, pelo que a gestão de armazéns cumpre um papel relevante neste contexto. O trabalho apresentado surgiu da necessidade de redimensionar um centro de distribuição e inclui a construção de dois modelos de programação linear que permitirão redimensionar e organizar o armazém. O primeiro modelo apresentado diz respeito ao dimensionamento das áreas funcionais e respectiva atribuição dos produtos a cada uma dessas áreas. O segundo modelo adopta uma política de localização baseada na formação de clusters. Os resultados obtidos abrem lugar ao estudo e implementação de novas estratégias para optimizar o processo de picking.