Multiechelon supply chains are complex logistics systems that require flexibility and coordination at a tactical level to cope with environmental uncertainties in an efficient and effective manner. To cope with these challenges, mathematical programming models are developed to evaluate supply chain flexibility. However, under uncertainty, supply chain models become complex and the scope of flexibility analysis is generally reduced. This paper presents a unified approach that can evaluate the flexibility of a four-echelon supply chain via a robust stochastic programming model. The model simultaneously considers the plans of multiple business divisions such as marketing, logistics, manufacturing, and procurement, whose goals are often conflicting. A numerical example with deterministic parameters is presented to introduce the analysis, and then, the model stochastic parameters are considered to evaluate flexibility. The results of the analysis on supply, manufacturing, and distribution flexibility are presented. Tradeoff analysis of demand variability and service levels is also carried out. The proposed approach facilitates the adoption of different management styles, thus improving supply chain resilience. The model can be extended to contexts pertaining to supply chain disruptions; for example, the model can be used to explore operation strategies when subtle events disrupt supply, manufacturing, or distribution.
Este artigo apresenta o desenvolvimento de uma metodologia de redução do tempo de preparação de máquina (tempo de changeover) para ambientes voláteis de manufatura contratada do setor eletroeletrônico e de informática.. As empresas desse setor fabricam uma grande variedade de produtos caracterizados por um alto valor agregado, curto ciclo de vida e instabilidade da demanda, exigindo flexibilidade das empresas para acompanhar o dinamismo do mercado. Com isso, a produção enxuta surge como uma alternativa, já que tem como características fluxo contínuo de produção, altos níveis de qualidade, redução de custos e agilidade na introdução de mudanças, fatores primordiais para se atingir a flexibilidade. O presente artigo tem como foco a redução do tempo de troca de ferramentas em uma linha de produção que utiliza a tecnologia de montagem em superfície conhecida como SMT (Surface Mount Technology). A diminuição desse tempo é relevante, pois possibilita a redução da necessidade de estoques intermediários; aumento da flexibilidade de produção com lotes e lead times menores; aumento de produtividade; respostas rápidas a mudanças de volume; e velocidade na programação da produção. A metodologia utilizada foi a pesquisa ação. O artigo traz contribuições teóricas e práticas além da aplicação da metodologia desenvolvida no setor de manufatura contratada. O método desenvolvido possibilitou ganhos importantes de flexibilidade de resposta a alterações de variedade e volume, traduzidos em ganhos de flexibilidade, produtividade e financeiros.
PurposeThe purpose of this paper is to present a new hybrid approach based on criticality analysis and optimisation to deal with spare parts inventory management in the initial provisioning phase in the mining industry. Spare parts represent a significant part of mining companies' expenditures, so it is important to develop new approaches to reduce the total inventory value of these items.Design/methodology/approachThis hybrid approach combines qualitative and quantitative methods based on VED (vital, essential and desirable) analysis, analytical hierarchical process (AHP), and e-constraint optimisation method to obtain the spare parts to be stocked. The study was applied to a large mining company. The mineral sector was chosen due to the great importance to the emerging Brazilian economy and the lack of researches in this sector. In addition, the spare parts have a relevant weight on the total inventory cost.FindingsPresent a novel approach combining multi-objective optimisation and multi-criteria evaluation approaches to tackle the inventory decision in spare parts management. This work also defines and classifies relevant criteria for spare parts management in the mineral sector validated by specialists. The proposed approach achieves an average increase of 20.2% in the criticality and 16.6% in the number of items to be stocked compared to the historical data of the surveyed company.Research limitations/implicationsThis paper applies the proposed approach to a mining company in Brazil. Future research in other companies or regions should analyse the adequacy of the criticality criteria, hierarchy and weights adopted in this paper.Practical implicationsThe proposed approach is useful for mining industries that deal with a large variety of resource constraints as it helps in formulating appropriate spare part strategies to rationalise financial resources at both tactical and strategic levels.Originality/valueThe paper presents a new hybrid method combining the AHP a multi-criteria decision making (MCDM) approach coupled with e-constraint optimisation to deal with spare parts inventory management allowing for a better spare parts inventory analysis in the initial provisioning phase and providing managers with a systematic tool to analyse the trade-off between spare parts criticality and total inventory value.
Goal: This study aims at solving a location problem of Medical Specialties Centers (MSCs) and medical care equipment allocation. Addressing both problems simultaneously is an opportunity to improve public health service quality in the long-term since the literature traditionally treats these problems separately. Design / Methodology / Approach: The challenge consists in maximizing demand satisfaction with the minimum resource allocation in the public health care reality, where there is limited resource availability and high demand for medical services. For that, it was developed an integrated mathematical model, throughout mixed linear programming. The problem is a case study applied to the secondary public health care level in a Brazilian state. The method is generic and suitable to set the location and allocate resources in health care if the decision maker’s intention is to maximize the use of specialists’ assistance and medical exams. Results: The results reveal possible improvements in accessibility. Among the insights, the state government should hire 4% more specialists and acquire 1.5% more equipment to assist 99% of population demand for health care service on the secondary level. Limitation of the investigation: Usually, one appointment can result in more than one medical exam referral. However, this study considers that each specialist meeting refers to only one exam per consultation. Practical implications: This study contributes to healthcare planning, suggesting a better distribution and allocation of facilities, equipment, and professionals. Moreover, the study proposes accessibility improvements to health unit centers. Originality / Value: The main contribution of this work is the new integrated approach to public health care planning. The system proposes the reduction of access inequality and the improvement of the quality of health care services.
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