Increasing Sustainability of Logistic Networks by Reducing Product Losses: A Network DEA Approach

This paper considers a multiproduct supply network, in which losses (e.g., spoilage of perishable products) can occur at either the nodes or the arcs. Using observed data, a Network Data Envelopment Analysis (NDEA) approach is proposed to assess the efficiency of the product flows in varying periods. Losses occur in each process as the observed output flows are lower than the observed input flows. The proposed NDEA model computes, within the NDEA technology, input and output targets for each process. The target operating points correspond to the minimum losses attainable using the best observed practice. The efficiency scores are computed comparing the observed losses with the minimum feasible losses. In addition to computing relative efficiency scores, an overall loss factor for each product and each node and link can be determined, both for the observed data and for the computed targets. A detailed illustration and an experimental design are used to study and validate the proposed approach. The results indicate that the proposed approach can identify and remove the inefficiencies in the observed data and that the potential spoilage reduction increases with the variability in the losses observed in the different periods.Ministerio de Ciencia DPI2017-85343-PFondo Europeo de Desarrollo Regional DPI2017-85343-

On the flexibility of an eco-industrial park (EIP) for managing industrial water

In a recent paper, a generic model, based on a multiobjective optimization procedure, for water supply system for a single company and for an eco-industrial park was proposed and illustrated by a park involving three companies A, B and C. The best configuration was identified by simultaneously minimizing the fresh water flow rate, the regenerated water flow rate and the number of connections in the eco-industrial park. The question is now to know what the maximal increase/decrease in pollutant flow rates is, so that the eco-industrial park remains feasible, economically profitable and environmentally friendly. A preliminary study shows that the park can accept an increase of pollutant flow rates of 29% in company A, 12% in company B and only 1% in company C; beyond these limits the industrial symbiosis becomes not feasible. The proposed configuration is not flexible with a very limited number of connections. Indeed, the solution implemented for conferring some flexibility to this network is to increase the number of connections within the park. However, connections have a cost, so the increase of their number needs to remain moderate. The number of connections is augmented until the symbiosis becomes unfeasible, or until the gain for each company to participate to the park becomes lower than a given threshold. Several cases are studied by increasing the pollutant flow rates under two different scenarios: 1) in only one company, 2) in two or three companies simultaneously

Multiobjective optimization of natural gas transportation networks

L'optimisation de l'exploitation d'un réseau de transport de gaz naturel (RTGN) est typiquement un problème d'optimisation multiobjectif, faisant intervenir notamment la minimisation de la consommation énergétique dans les stations de compression, la maximisation du rendement, etc. Cependant, très peu de travaux concernant l'optimisation multiobjectif des réseaux de gazoducs sont présentés dans la littérature. Ainsi, ce travail vise à fournir un cadre général de formulation et de résolution de problèmes d'optimisation multiobjectif liés aux RTGN. Dans la première partie de l'étude, le modèle du RTGN est présenté. Ensuite, diverses techniques d'optimisation multiobjectif appartenant aux deux grandes classes de méthodes par scalarisation, d'une part, et de procédures évolutionnaires, d'autre part, communément utilisées dans de nombreux domaines de l'ingénierie, sont détaillées. Sur la base d'une étude comparative menée sur deux exemples mathématiques et cinq problèmes de génie des procédés (incluant en particulier un RTGN), un algorithme génétique basé sur une variante de NSGA-II, qui surpasse les méthodes de scalarisation, de somme pondérée et d'ε-Contrainte, a été retenu pour résoudre un problème d'optimisation tricritère d'un RTGN. Tout d'abord un problème monocritère relatif à la minimisation de la consommation de fuel dans les stations de compression est résolu. Ensuite un problème bicritère, où la consommation de fuel doit être minimisée et la livraison de gaz aux points terminaux du réseau maximisée, est présenté ; l'ensemble des solutions non dominées est répresenté sur un front de Pareto. Enfin l'impact d'injection d'hydrogène dans le RTGN est analysé en introduisant un troisième critère : le pourcentage d'hydrogène injecté dans le réseau que l'on doit maximiser. Dans les deux cas multiobjectifs, des méthodes génériques d'aide à la décision multicritère sont mises en oeuvre pour déterminer les meilleures solutions parmi toutes celles déployées sur les fronts de Pareto. ABSTRACT : The optimization of a natural gas transportation network (NGTN) is typically a multiobjective optimization problem, involving for instance energy consumption minimization at the compressor stations and gas delivery maximization. However, very few works concerning multiobjective optimization of gas pipelines networks are reported in the literature. Thereby, this work aims at providing a general framework of formulation and resolution of multiobjective optimization problems related to NGTN. In the first part of the study, the NGTN model is described. Then, various multiobjective optimization techniques belonging to two main classes, scalarization and evolutionary, commonly used for engineering purposes, are presented. From a comparative study performed on two mathematical examples and on five process engineering problems (including a NGTN), a variant of the multiobjective genetic algorithm NSGA-II outmatches the classical scalararization methods, Weighted-sum and ε-Constraint. So NSGA-II has been selected for performing the triobjective optimization of a NGTN. First, the monobjective problem related to the minimization of the fuel consumption in the compression stations is solved. Then a biojective problem, where the fuel consumption has to be minimized, and the gas mass flow delivery at end-points of the network maximized, is presented. The non dominated solutions are displayed in the form of a Pareto front. Finally, the study of the impact of hydrogen injection in the NGTN is carried out by introducing a third criterion, i.e., the percentage of injected hydrogen to be maximized. In the two multiobjective cases, generic Multiple Choice Decision Making tools are implemented to identify the best solution among the ones displayed of the Pareto fronts

Eco-efficient Supply Chains for Electrical and Electronic Products

Hundreds of millions of electrical and electronic appliances are manufactured every year. Furthermore, it is expected that this number will not substantially decrease in the near future. These equipments have a significant impact on the environment, and ceteris paribus, such environmental impact increases with the number of appliances manufactured. Consumers, NGOs and Governments have acknowledged the potential threat posed by these electrical and electronic products. They have systematically demanded companies to reduce the environmental impact caused be their products and services. Companies have responded to these pressures and have engaged in a number of environmentally friendly initiatives. This thesis is motivated by the task of reducing the environmental impact caused by the myriad of electrical and electronic products that make our lives more conformable and enjoyable. More specifically, it addresses the challenge of efficiently and effectively mitigating such impacts. We show that companies will need a mixture of strategies to respond to this challenge. Furthermore, we show that these strategies must consider environmental, technical and marketing aspects of the business of electrical and electronic products. These three aspects need to be considered systemically, and the solutions will vary greatly according to the companies, the products they manufacture, and the ways in which their supply chains are organized

Operational research IO 2021—analytics for a better world. XXI Congress of APDIO, Figueira da Foz, Portugal, November 7–8, 2021

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.info:eu-repo/semantics/publishedVersio

Assessment of Socio-Economic Sustainability and Resilience after COVID-19

The pandemic period has caused severe socio-economic damage, but it is accompanied by environmental deterioration that can also affect economic opportunities and social equity. In the face of this double risk, future generations are ready to be resilient and make their contribution not only on the consumption side, but also through their inclusion in all companies by bringing green and circular principles with them. Policy makers can also favor this choice

Redesign of a sustainable food bank supply chain

Thesis submitted for the degree of Doctor of Philosophy in Mathematics Applied to Economics and Management.Food rescue and delivery organizations target concurrently the environmental objective of reduc- ing food waste, and the social objective of supporting underprivileged segments of the population. They secure surplus and about-to-waste food items from producers, manufacturers and retailers, and redistribute them through charitable agencies and parish councils to support the population in need of food assistance. Inspired by the case of the Portuguese Federation of Food Banks, the study ad- dresses the redesign of a food bank supply chain from a multi-dimensional outlook on sustainability. Considering an initial network of food banks, strategic decisions include the opening and closing of food banks, as well as the installation or expansion of storage and transport resources, while tactical decisions comprise the selection of served charities and respective assignment to the operational food banks. Moreover, product flows across the network are also to be determined. The supply chain is formulated as a three-layer network involving the donors, the food banks, and the charities, where multiple products flow in vertical and lateral directions. Based on an extensive literature review, and supported by an in-depth field research, the problem is formulated as a dynamic and capacitated tri-objective mixed-integer linear programming model, accounting for environmental indicators such as the volume of food waste and CO2 emissions, and social metrics assessing, among others, equity, inclusion, and proximity. The tri-objective problem is studied for regional and national supply chain instances, developed to depict real-life based cases. Non-dominated solutions are obtained for the regional instances appealing to the lexicographic ordering method. Relevant managerial insights are derived from the analysis of the lexicographic solutions. Three decomposition based heuristics de- veloped in this study proved to be effective in solving the national instances. Trade-offs between the economic, environmental, and social objectives are discussed, and properties of the mathematical programming model are proven.As organizações de resgate e distribuição "alimentar perseguem paralelamente o objetivo ambiental de redução do desperdício alimentar e o objetivo social de apoio à população carenciada. Estas entidades angariam excedentes alimentares e produtos em vias de deterioração de produtores, indústrias e do comércio a retalho que redistribuem, através de instituições de solidariedade e autarquias locais, a pessoas com carências alimentares. Inspirado no caso da Federação Portuguesa de Bancos Alimentares, este estudo aborda o redesenho de uma cadeia de abastecimento de bancos alimentares numa perspectiva de sustentabilidade multi-dimensional. Considerando uma rede inicial de bancos alimentares, as decisões estratégicas envolvem a abertura e o encerramento de bancos alimentares, bem como a instalação ou expansão da capacidade de armazenamento e de transporte, ao passo que as decisões táticas compreendem a seleção das instituições servidas e a sua afetação a algum dos bancos em operação. Adicionalmente, são também determinados os fluxos de produtos que circulam na rede. A cadeia de abastecimento é formulada como uma rede de três níveis envolvendo os doadores, os bancos alimentares e as instituições beneficiárias. Nesta rede existem fluxos verticais e laterais de produtos. Com base numa extensa revisão bibliográfica e apoiado por um aprofundado trabalho de campo, o problema é formulado como um modelo de programação linear inteira-mista, dinâmico, com capacidades e tri-objetivo. Este problema considera indicadores ambientais como o volume de desperdício alimentar e as emissões de CO2, e como métricas sociais a equidade, a inclusão e a proximidade, entre outros. O problema é estudado para instâncias de cadeias de abastecimento regionais e nacionais, as quais foram desenvolvidas com o objetivo de retratar casos baseados na realidade. São obtidas soluções não dominadas para as instâncias regionais recorrendo ao método lexicográfico, cuja análise revela conclusões relevantes para a gestão. Foram desenvolvidas três heurísticas baseadas em decomposição que provaram ser eficazes na resolução das instâncias nacionais. São discutidos os compromissos existentes entre os objetivos económico, ambiental e social, e provadas propriedades do modelo de programação matemática.N/