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Publicações

Publicações por SEM

2020

Optimization of Sustainable Single-Machine Scheduling Problem : Short Research Paper, CSCI-ISCI

Autores
Homayouni S.M.; Fontes D.B.M.M.;

Publicação
Proceedings - 2020 International Conference on Computational Science and Computational Intelligence, CSCI 2020

Abstract
This work considers sustainable scheduling of manufacturing operations and preventive maintenance activities in a single-machine environment where the machine works continuously in three eight-hour shifts per day. The jobs can be produced at different processing speeds, which reduces energy consumption and/or processing times. In a tri-objective mixed integer linear programming model, sustainability is attained through minimizing total weighted earliness/ tardiness - economic pillar, total energy consumption - environmental pillar, and number of undesired activities - social pillar. Moreover, a multi-objective genetic algorithm finds near optimal solutions in a timely manner. Numerical results will be presented at the conference.

2020

Cooperative coevolution of expressions for (r,Q) inventory management policies using genetic programming

Autores
Lopes, RL; Figueira, G; Amorim, P; Almada Lobo, B;

Publicação
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH

Abstract
There are extensive studies in the literature about the reorder point/order quantity policies for inventory management, also known as policies. Over time different algorithms have been proposed to calculate the optimal parameters given the demand characteristics and a fixed cost structure, as well as several heuristics and meta-heuristics that calculate approximations with varying accuracy. This work proposes a new meta-heuristic that evolves closed-form expressions for both policy parameters simultaneously - Cooperative Coevolutionary Genetic Programming. The implementation used for the experimental work is verified with published results from the optimal algorithm, and a well-known hybrid heuristic. The evolved expressions are compared to those algorithms, and to the expressions of previous Genetic Programming approaches available in the literature. The results outperform the previous closed-form expressions and demonstrate competitiveness against numerical methods, reaching an optimality gap of less than , while being two orders of magnitude faster. Moreover, the evolved expressions are compact, have good generalisation capabilities, and present an interesting structure resembling previous heuristics.

2020

Conceptualization of an information system for integrated management of public transport [Conceptualização de um sistema de informação para gestão integrada de transportes públicos]

Autores
Fontes, T; Sousa, J; De Sousa, JF;

Publicação
Atas da Conferencia da Associacao Portuguesa de Sistemas de Informacao

Abstract
Software requirements are key elements that contribute to the quality of systems and stakeholders' satisfaction. In the domain of public transport, many information systems have been developed; however, the majority is focused on operational planning and public transport control, discarding the strategic-tactical levels of action. While at operational level management, the control is usually centered on public transport providers, at the strategic and tactical levels, a close interaction from distinct types of stakeholders is required. Moreover, management is distinct among cities. This work aims to define the conceptualization of a configurable decision support system (DSS) for the tactical-strategic management of public transport. The various needs and perspectives of the stakeholders are taken into account, and the data used as a basis have high granularity. © Atas da Conferencia da Associacao Portuguesa de Sistemas de Informacao 2020.

2020

Decision-support challenges in the chemical-pharmaceutical industry: Findings and future research directions

Autores
Marques, CM; Moniz, S; de Sousa, JP; Barbosa Povoa, AP; Reklaitis, G;

Publicação
COMPUTERS & CHEMICAL ENGINEERING

Abstract
The chemical-pharmaceutical sector is facing an unprecedented fast-changing environment, with new market and technological trends impacting the companies' operational strategies. Managing the pharmaceutical supply chain (PSC) operations is, therefore, ever more complex and challenging. The goal of this work is to present a comprehensive overview of the current state of the industry and research developments; and then, to develop a new decision-making reference framework to assist in the creation of optimization-based decision support models. This will be achieved through a multi-perspective analysis that encompasses strategic and tactical planning decision-making, in the current and future business context of the chemical-pharmaceutical industry. The findings reveal a lack of research addressing the most prominent trends currently driving this sector, such as patient centricity or new technological developments, thus highlighting the disruptive nature of the expected changes in a highly conservative industry.

2020

The vehicle routing problem with backhauls towards a sustainability perspective: a review

Autores
Santos, MJ; Amorim, P; Marques, A; Carvalho, A; Povoa, A;

Publicação
TOP

Abstract
The vehicle routing problem with backhauls (VRPB) allows to integrate inbound and outbound routes, which is an efficient strategy to reduce routing costs and also to reduce the environmental and social impacts of transportation. In this paper, we analyze the VRPB literature with a sustainability perspective, which covers environmental and social objectives, collaborative networks and reverse logistics. First, to better understand and analyze the VRPB literature, all related works are characterized according to a common taxonomy provided for routing problems. This taxonomy is extended to differentiate between economic, environmental and social objectives. After identification of all VRPB papers that include sustainability issues, these are analyzed and discussed in more detail. The analysis reveals that research on VRPBs with sustainability concerns is recent and relatively scarce and the most popular aspects investigated are the minimization of fuel consumption andCO2 emissions. Future research lines driven by sustainability concerns are suggested for the VRPB as a promoter of green logistics.

2020

Leveraging logistics flows to improve the sludge management process of wastewater treatment plants

Autores
Henriques, AA; Fontes, M; Camanho, A; Gabriel Silva, JG; Amorim, P;

Publicação
JOURNAL OF CLEANER PRODUCTION

Abstract
In this paper, we propose an innovative approach to integrate the wastewater treatment (WWT) that is carried out in a set of plants and the anaerobic digestion (AD) that is carried out in a different set of plants, all from the same system. The aim is to contribute to sustainability improvements (e.g., cost reduction and environmental and social benefits) within the system. The main drivers that support this approach are the existence of unutilized capacity in some digesters and the possibility of reducing the process sludge age to maintain its biogas potential during the aerobic treatment in the plants without AD facilities. Furthermore, the effect of co-digestion as a means of enhancing the amount of biogas that can be produced through the sludge is also considered. This innovative approach leads to a mixed-integer linear programming (MILP) model to optimize the sludge flows that connect the plants without AD facilities to the ones with anaerobic digesters. The developed approach was applied to a Portuguese water utility and the results provide new insights for an optimized sludge management process of WWTPs, also indicating that the economic benefit obtained from the proposed strategy for sludge management can lead to a reduction of up to 23.5% in terms of current energy costs.

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