ABSTRACT Vehicle Routing Problems (VRP) have been widely researched throughout history as a way of optimising routes by minimising distances and planning deliveries efficiently, but the issue of risk in VRP has received less attention over time. This is essential to increasing transport safety to avoid interruptions in supply chains and improve delivery reliability. Therefore, this study aims to support decision makers to plan routes for road freight transportation considering not only the logistics cost, but also travel safety due to road hazards. An analytical approach based on statistics was developed in which data of vehicle accidents and road features were used to estimate the risk cost by using the Monte Carlo simulation. A bi-objective approach based on PROMETHEE II and ε-constrained methods was used in the Capacitated Vehicle Routing Problem (CVRP) to analyse the conflict between the logistic cost and accident risk. Key contributions of this study are an analytical approach based on statistics, Monte Carlo simulation and multicriteria methods in a CVRP model to explore the trade-off between logistic costs and accident risk expressed by a risk cost. The outcomes of this study show to be useful in practice to analyse transportation decisions in the VRP model involving route planning considering accident risk. (VRP efficiently time reliability Therefore hazards biobjective bi objective εconstrained ε constrained (CVRP tradeoff trade off

ABSTRACT A linear programming mathematical model was applied to a representative dairy farm located in Brazil. The results showed that optimization models are relevant tools to assist in the planning and management of agricultural production, as well as to assist in estimating potential gains from the use of integrated systems. Diversification was a necessary condition for economic viability. A total cost reduction potential of about 30% was revealed when a scenario of lower levels of diversification was contrasted to one of higher levels. Technical complementarities proved to be important sources of economies. The possibility of reusing nitrogen, phosphorus, and potassium present in animal waste could be increased to 167%, while water reuse could be increased up to 150%. In addition to economic gains, integrated systems bring benefits to the environment, especially with reference to the reuse of resources. The cost dilution of fixed production factors can help economies of scope to be achieved. However, this does not seem to have been the main source of these benefits. Still, the percentage of land use could increase up to 30.7% when the lowest and the highest diversification scenarios were compared. The labor coefficient could have a 4.3 percent increase. Diversification also leads to drastic transaction cost reductions.

Apresenta-se neste trabalho um modelo de programação linear inteira mista para apoiar algumas das principais decisões na operação de produção de vapor em caldeiras industriais. O modelo contempla as decisões de gerenciamento dos combustíveis: compra nos fornecedores, transporte para a fábrica e níveis dos estoques, assim como determina o modo de funcionamento das caldeiras: momentos de acionamento (start-up), regime de aquecimento (warm-up) e desligamento dos equipamentos (shutdown), e em quais deles haverá produção de vapor. Os ajustes e a validação do modelo ocorreram por meio de um estudo de caso realizado em uma indústria de alimentos de grande porte. Diante dos bons resultados obtidos com a aplicação do modelo e da ausência de protocolos ou ferramentas de otimização para apoiar as decisões no sistema estudado, o modelo proposto apresenta-se como uma alternativa viável para apoiar algumas das principais decisões no sistema de produção de vapor em caldeiras industriais.

In this study, a mixed integer linear programming model is presented to support some of the key decisions in the steam production system with industrial boilers. The model approaches the fuel management decisions (fuel replenishment and its inventory control), boiler operational decisions (start-up, warm-up, and shutdown operations), and which boiler should produce steam. The model adjustments and its validation were carried out through a case study in a large food industry. In face of the good outcomes achieved in applying the model and the lack of optimization tools to support the decisions in this system, the proposed model is a suitable alternative to support some of the key decisions in the system of steam production with multiple industrial boilers.

O suprimento de tomates para processamento industrial é uma atividade relativamente complexa. Plantas industriais de larga escala necessitam de elevados volumes diários de matéria-prima. Por outro lado, há alta perecibilidade dos frutos e a colheita ainda é predominantemente manual. Um modelo matemático foi desenvolvido com o propósito de entender objetivamente o processo de suprimento de tomate e, também, vislumbrar possibilidades de sua otimização. A simulação a partir do modelo pode gerar cenários que, quando comparados com o desempenho efetivamente observado em campo, evidenciam a importância da gestão acurada, com a presença de potenciais ganhos financeiros expressivos na cadeia de suprimentos a partir da redução de tempos, perdas e custos. As perdas de produto poderiam ser reduzidas de mais de 2% para algo inferior a 1%. A menor capacidade ociosa traduzir-se-ia em um menor custo de oportunidade e aumento de receita. Para uma fábrica com um consumo de tomates de 336 mil toneladas por ano, a melhoria no suprimento de matéria-prima poderia resultar em ganhos estimados em R$ 6 milhões por ano.

The supply of tomatoes for the manufacturing process is a quite complex activity. Everyday large amounts of vegetables and fruits to be processed need to be stored. Their perishability has to be considered and the harvest is still manual in the majority of producing areas. Evidences show the existence of high levels of losses in the supply logistic process. A mathematical model was developed with the objective of allowing better knowledge of the whole process and investigating possibilities of optimization. The simulation using the model can generate scenarios that when compared with real performances show the importance of an accurate management with evident potential of expressive financial gains in the supply chain process with the reduction of time, losses and costs. The losses of products, which are regularly more than 2%, could be reduced to less than 1% and the option of not operating at full production capacity could also lower the costs generating higher revenues. To a plant with a processing volume of 336 thousand tons per season, the improvements of the supply process could result in gains estimated in R$ 6 millions.