Papers by Tânia Pinto-Varela
Springer proceedings in mathematics & statistics, Dec 31, 2022
Journal of Cleaner Production
Decision Support Systems, Jul 1, 2023
Computer-aided chemical engineering, 2023
Computer-aided chemical engineering, 2023
Computer Aided Chemical Engineering
Chemical Engineering Research and Design
Springer proceedings in mathematics & statistics, Jul 22, 2019
Parallel production lines are a design option often used in chemical batch plants. In recent rese... more Parallel production lines are a design option often used in chemical batch plants. In recent research, this option has been introduced into the strategic multiproduct batch plant design problem, assuming a single product campaign mode of operation. However, to accommodate for other modes of operation and different production strategies, more explicit scheduling should be considered. In this paper, the combined design and scheduling optimization of multiple lines multistage plants is addressed. More specifically, we explored the Resource-Task Network formulation, in which constraints were included to exploit the sequential characteristics of the problem under study. Furthermore, two solution approaches were studied: a general holistic one and, triggered by the rapid increase in problem size and computational expense, a decomposition approach. In this decomposition approach, the problem is divided into smaller subproblems, by fixing the number of lines, which are iteratively solved. T...
This paper presents a multi-objective approach considering a mixed integer linear programing (MIL... more This paper presents a multi-objective approach considering a mixed integer linear programing (MILP) model, based on a continuous-time Resource Task Network (RTN) formulation, for the optimal planning management of biopharmaceutical processes. The model assesses the manufacturing constraints for the determination of the optimal production schedule while considering the simultaneous maintenance planning of downstream units, subject to performance decay. The optimal results of an illustrative medium-term planning problem of a biopharmaceutical process, addressing the main bioprocesses regulations, is analysed through a multi-objective approach considering the augmented e-constraint method. The evaluation of the Pareto sets for two bi-objective analyses is performed, considering the profit maximisation with the minimisation of the number of intermediate maintenance operations and the maximisation of average service level, while comparing the different solutions towards the decision make...
The increasingly competitivity in the plastic container market is driving companies toward a grea... more The increasingly competitivity in the plastic container market is driving companies toward a greater focus on efficiency, and mass production customisation, which triggers the increase of productivity by implementing more efficient and faster IT solutions. This work is based on a Portuguese case study, to develop a scheduling model considering the specific characteristics of this type of facilities and increase its competitiveness. To this end, two different approaches, the Tabu Search and Genetic Algorithm, were developed to solve a flexible job shop scheduling problem under a make-to-order production strategy. Each approach was validated using the case study, and the model’s applicability were testes trough five instances. The results have shown that Tabu Search has a better efficacy and the Genetic Algorithm shows better efficiency.
Computer Aided Chemical Engineering, 2012
Abstract The design of supply chains has been mainly focused on economic indicators. However, as ... more Abstract The design of supply chains has been mainly focused on economic indicators. However, as social and environmental concerns grow in society it has become clear that such aspects also need to be accounted when designing supply chains. Thus investment towards logistics structures that consider both economic and environmental performance is nowadays an important research topic. This paper address such topic and studies the design and planning of multi-product supply chain networks (SCN), while accounting simultaneously with economic and environmental aspects. The latter are modeled through the use of the Life Cycle Assessment (LCA). On the LCA two methodologies are studied, the Eco-Indicator 99 and the Environmental Priority Strategies (EPS). The optimization of the SCN is performed through a mixed integer linear programming (MILP) formulation. The model is constructed based on the Resource-Task-Network (RTN) where the applicability of the Eco-indicator 99 and the EPS methodologies are considered. The results obtained are analyzed using different objective functions (economic, environmental and mixed).
Computer Aided Chemical Engineering, 2014
To be competitive in the global market, companies need to ensure that they run more efficient tha... more To be competitive in the global market, companies need to ensure that they run more efficient than ever. This fact forces companies to apply continuous improvement actions in their plants which often involve a series of retrofitting activities that have to be conducted during the whole Life Cycle of their industrial process. Within this context, the present work proposes a framework, BatchRetroLC, which aims to guide decision- makers in continuous improvement actions, leading to a sequence of iterative improvement steps. BatchRetroLC integrates an indicator based methodology, SustainPro, with optimization models developed for the batch retrofit problem. The applicability of the proposed framework is shown through a multipurpose batch plant case study.
Computer Aided Chemical Engineering, 2014
Abstract In this paper, a scheduling model is presented for biopharmaceutical processes. The prop... more Abstract In this paper, a scheduling model is presented for biopharmaceutical processes. The proposed Mixed Integer Linear Programing (MILP) formulation extends the unified continuous-time Resource-Task Network (RTN) representation presented by Castro et al. (2004). Two of the main characteristics required in the bioprocesses scheduling, which are the lots traceability of different productions and the shelf-life storage limitations, are considered. An illustrative example from the literature is used to demonstrate the applicability of the proposed formulation.
Industrial & Engineering Chemistry Research, 2009
This work deals with the design of multipurpose batch plants under uncertainty. The model propose... more This work deals with the design of multipurpose batch plants under uncertainty. The model proposed by Pinto et al. [1] for the detailed design of batch plants is extended to address the problem of uncertainty associated with production demands. Equipment choices as well as plant topology and associated schedule are defined simultaneously under an uncertain environment. Demand uncertainty is considered as a set of scenarios and probabilities are assumed to be known a priori. A cyclic operation is assumed where time is treated using a uniform discrete time grid. Mixed storage policies and sharing of resources are considered and a MILP formulation is obtained. An illustrative example is solved to test the model applicability.
This paper addresses simultaneously strategic and tactical aspects of the design and planning of ... more This paper addresses simultaneously strategic and tactical aspects of the design and planning of multiproduct supply chain networks, while accounting not only for economic but also environmental aspects under an uncertain market setting. At the strategic level the design of the supply chain network, as well as the set of technologies associated to the multi-product and multipurpose production facilities are selected. At the tactical level the planning details related to demand satisfaction are defined, considering the selected design and technologies. A two-stage stochastic mixed integer linear programming (MILP) approach is proposed taking into account a time varying demand uncertainty along pre-defined periods during the assumed planning horizon. Risk management aspects are modelled through a financial risk model incorporated into the stochastic programming formulation. Finally, a multi-objective optimization approach is developed to establish the trade-off between profit, risk and environmental impacts. The effectiveness of the proposed approach is shown through the solution of an illustrative example.
Mathematics
Industrial production facilities have been facing the requirement to optimise resource efficiency... more Industrial production facilities have been facing the requirement to optimise resource efficiency, while considering sustainable goals. This paper addresses the introduction of renewable energies in production by exploring the combined design and scheduling of a multipurpose batch facility, with innovative consideration of direct/indirect heat integration using a solar energy source for thermal energy storage. A mixed-integer linear programming model is formulated to support decisions on scheduling and design selection of storage and processing units, heat exchange components, collector systems, and energy storage units. The results show the minimisation of utilities consumption, with an increase in the operational profit using combined heat integration strategies for the production schedule. A set of illustrative case-study examples highlight the advantages of the solar-based heat storage integration, assessing optimal decision support in the strategic and operational management of...
Computer Aided Chemical Engineering, 2012
Abstract Nowadays it is becoming increasingly more important to incorporate environmental and soc... more Abstract Nowadays it is becoming increasingly more important to incorporate environmental and social perspectives into problems that in the past were subject to analysis focused only on economic aspects. Specifically, the emerging sustainability concerns on Supply Chain Networks (SCN) optimization contemplate environmental impacts associated with their activities, without ignoring the economic perspective. The combination of these different and frequently antagonistic aspects leads to a complex problem formulation that can be modeled with a bi-objective mixed linear programming. Unfortunately, the nature and dimension of these problems usually imply large formulations that come associated with a high computational burden. In order to overcome this difficulty, a meta-heuristic approach, based on the Simulated Annealing (SA) methodology is developed and a sensitivity analysis is made on the main parameters. The performance of the proposed methodology is compared with an exact approach with the support of a Pareto frontier.
Nowadays, we are facing the fourth industrial revolution, which is triggering businesses’ need to... more Nowadays, we are facing the fourth industrial revolution, which is triggering businesses’ need to increase efficiency and productivity, in real time. To accomplish this challenge, decision systems to support the decision maker in real time and at operational level is necessary. In this work a bi-objective approach using a simulated annealing algorithm in industrial context is addressed, where a make-to-stock production strategy is followed. In the first stage, the total tardiness minimization is reached, followed by the total production flow time minimization. A case study from a multinational moulding industry operating with several parallel machines is used to illustrate the algorithm’s applicability.
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Papers by Tânia Pinto-Varela