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Publicações

Publicações por SEM

2023

The Floating-Cuts model: a general and flexible mixed-integer programming model for non-guillotine and guillotine rectangular cutting problems

Autores
Silva, E; Oliveira, JF; Silveira, T; Mundim, L; Carravilla, MA;

Publicação
OMEGA-INTERNATIONAL JOURNAL OF MANAGEMENT SCIENCE

Abstract
Cutting and packing problems are challenging combinatorial optimization problems that have many rel-evant industrial applications and arise whenever a raw material has to be cut into smaller parts while minimizing waste, or products have to be packed, minimizing the empty space. Thus, the optimal solution to these problems has a positive economic and environmental impact. In many practical applications, both the raw material and the cut parts have a rectangular shape, and cut-ting plans are generated for one raw material rectangle (also known as plate) at a time. This is known in the literature as the (two-dimensional) rectangular cutting problem. Many variants of this problem may arise, led by cutting technology constraints, raw-material characteristics, and different planning goals, the most relevant of which are the guillotine cuts. The absence of the guillotine cuts imposition makes the problem harder to solve to optimality.Based on the Floating-Cuts paradigm, a general and flexible mixed-integer programming model for the general rectangular cutting problem is proposed. To the best of our knowledge, it is the first mixed inte-ger linear programming model in the literature for both non-guillotine and guillotine problems. The basic idea of this model is a tree search where branching occurs by successive first-order non-guillotine-type cuts. The exact position of the cuts is not fixed, but instead remains floating until a concrete small rect-angle (also known as item) is assigned to a child node. This model does not include decision variables either for the position coordinates of the items or for the coordinates of the cuts. Under this framework, it was possible to address various different variants of the problem.Extensive computational experiments were run to evaluate the model's performance considering 16 dif-ferent problem variants, and to compare it with the state-of-the-art formulations of each variant. The results confirm the power of this flexible model, as, for some variants, it outperforms the state-of-the-art approaches and, for the other variants, it presents results fairly close to the best approaches. But, even more importantly, this is a new way of looking at these problems which may trigger even better approaches, with the consequent economic and environmental benefits.

2023

The Role of Digitalization, Servitization and Innovation Ecosystem Actors in Boosting Business Model Innovation – A Literature Review

Autores
Mesquita, M; Simões, AC; Teles, V;

Publicação
Lecture Notes in Mechanical Engineering

Abstract
The Industry 4.0 technologies and servitization are requiring manufacturers to reinvent themselves to remain competitive. In this sense, companies are putting more emphasis on the customer experience, while associating services to their products with the support of emerging technologies. At the same time, actors in the innovation ecosystem such as universities, research institutes, and service providers are involved in the value co-creation process. Thus, this study aims to systemize and present the main findings of a literature review regarding the role of digitalization, servitization, and innovation ecosystem actors in boosting innovation in business models. The study involved 585 articles in international journals and conference proceedings published till 2021. A detailed selection process led 10 articles for further analysis. As a consequence of digitalization and servitization, there has to be an alignment among ecosystem actors to capture the co-created value generated by BMI. Moreover, the combination of BMI, servitization, and digitalization may also be structured into frameworks according to the different levels of each of those factors, thus allowing for companies to assess and position themselves in such frameworks and identify the path to follow. However, any of these articles addressed the combination of the three topics proposed: digitalization, servitization, and the contribution of the innovation ecosystem actors, even if they showed a clear interdependence between these areas, leading to common findings impacting BMI. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

2023

Time Series of Counts under Censoring: A Bayesian Approach

Autores
Silva, I; Silva, ME; Pereira, I; McCabe, B;

Publicação
ENTROPY

Abstract
Censored data are frequently found in diverse fields including environmental monitoring, medicine, economics and social sciences. Censoring occurs when observations are available only for a restricted range, e.g., due to a detection limit. Ignoring censoring produces biased estimates and unreliable statistical inference. The aim of this work is to contribute to the modelling of time series of counts under censoring using convolution closed infinitely divisible (CCID) models. The emphasis is on estimation and inference problems, using Bayesian approaches with Approximate Bayesian Computation (ABC) and Gibbs sampler with Data Augmentation (GDA) algorithms.

2023

Towards a Comprehensive Framework for the Multidisciplinary Evaluation of Organizational Maturity on Business Continuity Program Management: A Systematic Literature Review

Autores
Russo, N; Reis, L; Silveira, C; Mamede, HS;

Publicação
INFORMATION SECURITY JOURNAL

Abstract
Organizational dependency on Information and Communication Technology (ICT) drives the preparedness challenge to cope with business process disruptions. Business Continuity Management (BCM) encompasses effective planning to enable business functions to resume to an acceptable state of operation within a defined timeframe. This paper presents a systematic literature review that communicates the strategic guidelines to streamline the organizational processes in the BCM program, culminating in the Business Continuity Plan design, according to the organization's maturity. The systematic literature review methodology follows the Evidence-Based Software Engineering protocol assisted by the Parsifal tool, using the EbscoHost, ScienceDirect, and Scopus databases, ranging from 2000 to February 2021. International Standards and Frameworks guide the BCM program implementation, however, there is a gap in communicating metrics and what needs to be measured in the BCM program. The major paper result is the confirmation of the identified gap, through the analysis of the studies that, according to the BCM components, report strategic guidelines to streamline the BCM program. The analysis quantifies and discusses the contribution of the studies on each BCM component to design a framework supported by metrics, that allows assessing the organization's preparedness in each BCM component, focusing on Information Systems and ICT strategies.

2023

Towards an Ontology to Enforce Enterprise Architecture Mining

Autores
Pinheiro, CR; Guerreiro, S; Mamede, HS;

Publicação
Proceedings of the 25th International Conference on Enterprise Information Systems, ICEIS 2023, Volume 2, Prague, Czech Republic, April 24-26, 2023.

Abstract
Enterprise Architecture (EA) is a coherent set of principles, methods, and models that express the structure of an enterprise and its IT landscape. EA mining uses data mining techniques to automate EA modelling tasks. Ontologies help to define concepts and the relationships among these concepts to describe a domain of interest This work presents an extensible ontology for EA mining focused on extracting architectural models that use logs from an API gateway as the data source. The proposed ontology was developed using the OntoUML language to ensure its quality and avoid anti-patterns through ontology rule checks. Then, a hypothesized scenario using data structures close to the real is used to simulate the ontology application and validate its theoretical feasibility as well as its contribution to the Enterprise Architecture Management field. Copyright © 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

2023

Managing Disruptions in a Biomass Supply Chain: A Decision Support System Based on Simulation/Optimisation

Autores
Piqueiro, H; Gomes, R; Santos, R; de Sousa, JP;

Publicação
SUSTAINABILITY

Abstract
To design and deploy their supply chains, companies must naturally take quite different decisions, some being strategic or tactical, and others of an operational nature. This work resulted in a decision support system for optimising a biomass supply chain in Portugal, allowing a more efficient operations management, and enhancing the design process. Uncertainty and variability in the biomass supply chain is a critical issue that needs to be considered in the production planning of bioenergy plants. A simulation/optimisation framework was developed to support decision-making, by combining plans generated by a resource allocation optimisation model with the simulation of disruptive wildfire scenarios in the forest biomass supply chain. Different scenarios have been generated to address uncertainty and variability in the quantity and quality of raw materials in the different supply nodes. Computational results show that this simulation/optimisation approach can have a significant impact in the operations efficiency, particularly when disruptions occur closer to the end of the planning horizon. The approach seems to be easily scalable and easy to extend to other sectors.

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