Papers by Ana Cristina Santos Amaro
Computer-aided chemical engineering, 2023
Sustainability, Apr 28, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Computer-aided chemical engineering, 2005
In this paper a new continuous-time mathematical formulation is proposed for the optimal schedule... more In this paper a new continuous-time mathematical formulation is proposed for the optimal schedule of industrial supply chains. This introduces novel concepts to represent the supply chain instances (sites, equipment units, transportation facilities, etc) suitable events (transforming operations, transportation tasks, storage) and material states. Furthermore, it establishes a better commitment between the events allocation and the time scale associated. A single level formulation is obtained that allows the computation of the optimal supply chain schedule for a defined economical or operational performance criterion while accounting simultaneously for the explicit integration of different topological and operational characteristics of the supply chain dynamics. The formulation is a Mixed Integer Linear Programming (MILP) that is solved using a standard Branch and Bound (B&B) procedure. The applicability of the proposed formulation is illustrated through the solution of a practical example involving an industrial pharmaceutical chain.
Computers & Chemical Engineering, Jun 1, 1999
The scheduling of two types of distribution manifolds (single and double seat valves) typically f... more The scheduling of two types of distribution manifolds (single and double seat valves) typically found in multipurpose facilities has recently been presented by Amaro and Barbosa-Póvoa (1998). The mathematical formulation proposed permits a detailed consideration of the scheduling problem where important aspects such as operational pre-conditions and constraints are considered.In this paper, this model is extended to address the design of distribution manifolds. Scheduling and structural aspects are considered within a single level problem formulation. Operational constraints and simultaneous operation of compatible flowpaths, with different transfer times, are accounted for. All problems are formulated as MILPs and solved using a Branch and Bound procedure.An example illustrating the flexibility and the applicability of the new formulation to the design of distribution manifolds is presented.
Industrial & Engineering Chemistry Research, Mar 25, 2011
In this paper the optimal planning of supply chains is studied. Two alternative formulations are ... more In this paper the optimal planning of supply chains is studied. Two alternative formulations are developed to model the supply chain optimal planning: a discrete and a continuous-time formulation. The former considers the uniform split of the planning horizon into equal time intervals while the continuous-time counterpart involves the definition of a set of time slots, of unknown duration. Each slot dimension is optimized simultaneously with the planning events. Both approaches account explicitly for the integration of topological, operational, and market supply demand constraints and requirements. The supply of final products (forward flows) and the return of nonconform products (reverse flows) are simultaneously coordinated at the planning level of the supply chain optimization. The proposed formulations result into mixed integer linear programming (MILP's) models. A detailed plan is obtained for each formulation approach, which improves the supply chain operability by exploiting general resource capacities (e.g., transforming, storage, and transportation) and resource sharing policies based on the suitability of equipment/tasks, economical performances, and operational conditions. The applicability of the proposed formulations is illustrated through the solution of an industry-oriented case study.
European Journal of Operational Research, Dec 1, 1999
The scheduling of two types of manifolds typically found in multipurpose plants is considered. Th... more The scheduling of two types of manifolds typically found in multipurpose plants is considered. These are, respectively, single and double seat valve manifolds. Although they perform the same general function they are characterised by dierent operational and structural characteristics. Within the general scheduling problem important aspects such as operational preconditions and constraints are considered (e.g. product sequencing and cleaning requirements). These must be guaranteed during operation in order to avoid compromising ®nal product quality, safety and feasibility of operation. The¯owpath formulation proposed by Barbosa-P ovoa and Macchietto [4] for the scheduling of distribution manifolds is extended so as to account for operational conditions, modelled through the equipment State Task Network (eSTN) representation [3] and to allow for simultaneous operation of compatible¯owpaths with dierent transfer times. Operating objectives such as due dates, maximal production and production pro®t are considered. A Mixed Integer Linear Programming (MILP) formulation is developed and solved using a Branch and Bound (B&B) standard procedure. Binary variables are used to represent the operational choices that have to be made. An example illustrating thē exibility and applicability of the new formulation to the scheduling of distribution manifolds dealing with operating constraints is presented.
Computer-aided chemical engineering, 2006
In this paper a general model formulation is developed that accounts for the close loop supply ch... more In this paper a general model formulation is developed that accounts for the close loop supply chain structural and dynamic characteristics. Two sequential decision levels are considered: (i) planning and (ii) scheduling. The former defines the assignment of operations and associated amounts (supply, production, packing, transportation and distribution) to the suitable chain structures (plants, factories, transportation fleets, warehouses) so that
We examine the main existing challenges that currently arise in the assessment of European Union ... more We examine the main existing challenges that currently arise in the assessment of European Union (EU) funds devoted to three thematic objectives (TOs): Research and Innovation (R&I); Low-carbon economy (LCE); and Information and Communication Technologies (ICT). In this regard, a literature review on the European Regional Development Fund (ERDF) initiatives is performed, with a special focus on the Portuguese (PT) case, also addressing their assessment and reporting practices. Data systematization is coupled with the European Commission (EC)'s main guidelines and with the guidance recommendations brought by Management authorities (MA) for the 2014-2020 period. A bibliometric analysis is conducted to further understand the current research interest in the evaluation of EU funds, and the type of assessment methods and reporting practices employed. Most of the approaches rely on cost-benefit analysis and place less attention on data availability, variable selection, and monitoring/assessment options. The selection and application of the framework indicators, either related to their financial execution or achievement, are assumed as critical factors concerning the monitoring, reporting, and assessment processes. Our findings emphasize the need for harmonization and simplification of the reporting techniques, also highlighting the sparse data availability and some reporting conflicts.
Computer-aided chemical engineering, 2004
The competitive pressure and market globalisation as well as the relation between price, quality ... more The competitive pressure and market globalisation as well as the relation between price, quality and product lifetime are some major factors that underline the need for new planning policies that can handle global supply chain structures and dynamics so as to improve the desired economical and operational performances. In this paper a new framework is develop for the operation of industrial supply chains. This allows the integration of different topological, operational and processing preconditions constraints into a single level formulation. The proposed model relies on the discretization of time horizon into intervals of equal duration and results from the linkage between the maximal State-task Network, mSTN and the Flowpaths representations (Barbosa-Póvoa, 1994, PhD Thesis Imperial College; Amaro and Barbosa-Póvoa, 1999, EJOR, 199, 461-478) adapted to the supply chain characteristics. Supply chain structural and dynamic characteristics are studied. In the former aspects such as suppliers, plants, distribution centres, storage and transportation facilitiesnetwork structure-are modelled while in the later operating policies and production, storage, distribution or transportation requirements are considered. Also, possible operational preconditions within the products production as well as market considerations presented in the supply-demand relations are accounted for. Based on these characteristics a Mixed Integer Linear Programming (MILP), formulation is obtained and solved using standard Branch and Bound (B & B) procedures. A detailed operational plan is obtained where not only transportation aspects are considered but also production and storage considerations are included within the supply chain so as optimise a pre-defined economical or operational performance criteria. Finally, the flexibility and applicability of the new formulation to the scheduling of supply chain structures is illustrated through of a case-study.
Elsevier eBooks, 2007
In this paper the planning of closed loop supply chains is studied where both. forward and return... more In this paper the planning of closed loop supply chains is studied where both. forward and return flows are integrated considering their simultaneous coordination. The product supply and returns are then considered explicitly at the planning level of the supply chain optimization. Two different approaches are developed and implemented to model the supply chain optimal planning problem: a discrete and a continuous-time formulation. The former considers an uniform discretization of the planning horizon while the continuous-time counterpart considers the time space domain modeled through the definition of a set of time instances called slots of unknown duration. Each slot dimension is optimized simultaneously with the planning events. Both approaches account explicitly for the integration of topological, operational and market supply-demand constraints and requirements (Amaro and Barbosa-Póvoa, 2006). The proposed formulations results both into Mixed Integer Linear Programming (MILP's) models that are solved using a standard Branch and Bound (B&B) procedure. A detailed plan is obtained, at each formulation approach, that allows the improvement of the supply chain operability by exploiting general resource capacities (e.g. transforming, storage and transportation) and resource sharing policies based on equipment/tasks suitability's, economical performances and operational restrictions. 2 A.C.S. Amaro et al. The applicability of the proposed formulations is illustrated by its implementation on the solution of an industry-oriented case study involving an international pharmaceutical supply chain.
Computers & Chemical Engineering, Dec 1, 2009
In a global economy, the key to success is providing products around the world at the right time ... more In a global economy, the key to success is providing products around the world at the right time in the right quantity and quality, at a low cost. Efficient supply chains have an important role in guaranteeing this success. Optimized planning of such structures is required and ...
Elsevier eBooks, 2013
Abstract In this paper a new model formulation is proposed to help the decision making process at... more Abstract In this paper a new model formulation is proposed to help the decision making process at the planning level of industrial supply chains. This accounts for the tradeoff between sustainability and economic criteria and focus on the optimization of collaborative forward flows of products (open loop SC sustainability) in order to achieve sustainability pre-conditions and to enhance a profitable planning strategy. A Mixed Integer Linear Model (MILP) formulation is developed. A detailed operational plan is obtained where the production, distribution, storage and transport allocation is defined along the planning horizon while evaluated for different sustainability scenarios. The model applicability is shown through the solution of an industrial case-study.
Sustainability, Sep 15, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Industrial & Engineering Chemistry Research, Nov 30, 2007
In this paper, a new formulation is presented for the optimal scheduling of industrial supply cha... more In this paper, a new formulation is presented for the optimal scheduling of industrial supply chains. This is accomplished through the development of a master representation model, the ChainSTN, that unambiguously describes the supply chain topology, resources, operations, and involved materials. Also, different market opportunities (supply, demand, and price options) and manufacturing and transport considerations are regarded. By combining these concepts with a discrete and uniform representation of the scheduling time domain, a mixed-integer linear programming formulation (MILP) is attained. A detailed optimal scheduling plan is obtained, where different (i) operational decisions, describing the operations of the entire partners network; (ii) transportation policies, detailing the material flows among partners; and (iii) market options (provider's conditions and customers' demand orders) are jointly scheduled so as to optimize a global economical criterion, in here, the supply chain global profit. The flexibility and applicability of the new formulation are validated through the solution of an industrial example where different operational scenarios are discussed.
Computers & Chemical Engineering, Nov 1, 2008
This paper presents a modeling approach for the sequential planning and scheduling of supply chai... more This paper presents a modeling approach for the sequential planning and scheduling of supply chain (SC) structures with reverse flows. At the planning level an aggregated description is proposed to represent the supply chain operational problem. A master representation is defined to support supply chain resources, operational occurrences (events), involved materials and associated markets. Based on this master representation a
We assessed the execution of European Regional Development Funds (ERDF) allocated to promote a Lo... more We assessed the execution of European Regional Development Funds (ERDF) allocated to promote a Low-carbon economy (LCE) in 23 EU Member States (MS). Each MS is evaluated using the Value-Based Data Envelopment Analysis (VBDEA) method. In the first stage, the efficient MS were identified, and the major reasons that might affect the efficient performance of the ERDF. From the results obtained, 43% of the MS were deemed efficient in the application of ERDF committed to fostering an LCE, and these results were mostly justified by their financial spending rate. At the second stage of the analysis, the changes that needed to be done by inefficient MS to "try and replicate" their efficient counterparts were computed. Furthermore, from the robustness assessment conducted it was possible to show that with thresholds of δ = 5% and δ = 10%, 22% of the MS managed to attain a robust efficiency. While Spain is the leading country in terms of robustness efficiency, Romania (robustly inefficient for δ = 5%), Hungary, and the Czech Republic (the worst in the ranking of inefficient MS) could not apply these funds properly. Given this information, the EU should continue to push policies that secure financial opportunities from engaging in LCE, particularly for MS with limited financial capacities, while still supplying them with improved funding mechanisms and technical expertise.
2022 17th Iberian Conference on Information Systems and Technologies (CISTI), Jun 22, 2022
International Journal of Information Systems in The Service Sector, Apr 1, 2021
This paper studies the food waste problem in private and public collective catering units (CCU), ... more This paper studies the food waste problem in private and public collective catering units (CCU), served by a Portuguese catering company. The main objective is to develop data analysis and decision tools that may contribute to the waste control and to the operational planning of CCU. A set of novel key performance indicators (KPIs) are settled and evaluated to characterize food waste over time. For these indicators, several representations were studied, tested, and validated to create a dashboard intended to be clear and intuitive, regarding the food wastes. Operating practices require simple, objective, replicable, and ideally inexpensive data collection procedures. So, the proposed solution accounts for the trade-off between the details of the created data model and the associated data synthesis and visualization. The proposal (indicators and dashboard) was submitted to four weeks of tests, in six CCUs. The organizational validation achieved allows the conclusion about the interest of this contribution.
This paper intends to characterize the food waste of a unit, in which a Collective Restoration Co... more This paper intends to characterize the food waste of a unit, in which a Collective Restoration Company (ERC) operates, through the daily collection of data and monitoring of the amount of waste produced, per meal period, in the observed time horizon. The treatment and analysis of the collected data allowed to point out a set of performance indicators that could characterize food waste over time, according to the following categories: i) food waste index (ADI), ii) number of meals waste “(NRD) and iii) generated waste accumulator (ADG). For these indicators, several representation (visualization and synthesis) supports were identified and studied to create a dashboard that is intended to be objective and intuitive concerning the reading of waste generated in an ERC. The aim of the work in progress is to develop a proposal for the representation of waste indicators, which allows the identification of consumption patterns, contributing to daily planning and decision making in ERCs. Developments in progress are intended to contribute to reducing the levels of waste through ongoing support in the planning and preparation of menus. Resource management and good operating practices require simple, objective, replicable and ideally inexpensive collection procedures. In this sense, a compromise solution is presented between the operationalization of the collection (observations and representation), the details of the data collected and their synthesis and visualization in an operational dashboard. The applicability of the proposal under development (indicators and dashboard) was subject to some tests with real data of an ERC, being the current study a first contribution to the treatment of the sustainability problems generated by the wastes produced in this sector of activity.
This paper describes the work developed and the knowledge acquired from the implementation of a d... more This paper describes the work developed and the knowledge acquired from the implementation of a dashboard in a research and innovation system organization, CTCV. The research presents the motivations that led to the implementation of tools that allow the organization to obtain information from the data it produces daily. The achievement of that objective included the creation of key performance indicators (Key Performance Indicators, KPI) and the development of an analytical model, with a view to implementing these indicators in a dashboard, elaborated using Microsoft's Business Intelligence tool, the Power BI. As a result, the proposed solution is explored, as a management and decision support system, at the operational and strategic level, which allows CTCV decision makers to access relevant information in real time and in a dynamic and interactive way. The study also reveals the opportunity to apply the developed indicators to other organizations.
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Papers by Ana Cristina Santos Amaro