Escola Superior de Tecnologia e Gestão
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Browsing Escola Superior de Tecnologia e Gestão by Sustainable Development Goals (SDG) "12:Produção e Consumo Sustentáveis"
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- 3D printing of new biobased unsaturated polyesters by microstereo-thermal-lithographyPublication . Gonçalves, Filipa A. M. M.; Costa, Cátia S. M. F.; Fabela, Inês G. P.; Farinha, Dina; Faneca, Henrique; Simões, Pedro N.; Serra, Arménio C.; Bártolo, Paulo J.; Coelho, Jorge F. J.New micro three-dimensional (3D) scaffolds using biobased unsaturated polyesters (UPs) were prepared by microstereo-thermal-lithography (μSTLG). This advanced processing technique offers indubitable advantages over traditional printing methods. The accuracy and roughness of the 3D structures were evaluated by scanning electron microscopy and infinite focus microscopy, revealing a suitable roughness for cell attachment. UPs were synthesized by bulk polycondensation between biobased aliphatic diacids (succinic, adipic and sebacic acid) and two different glycols (propylene glycol and diethylene glycol) using fumaric acid as the source of double bonds. The chemical structures of the new oligomers were confirmed by proton nuclear magnetic resonance spectra, attenuated total reflectance Fourier transform infrared spectroscopy and matrix assisted laser desorption/ionization-time of flight mass spectrometry. The thermal and mechanical properties of the UPs were evaluated to determine the influence of the diacid/glycol ratio and the type of diacid in the polyester's properties. In addition an extensive thermal characterization of the polyesters is reported. The data presented in this work opens the possibility for the use of biobased polyesters in additive manufacturing technologies as a route to prepare biodegradable tailor made scaffolds that have potential applications in a tissue engineering area.
- 3D shape prior active contours for an automatic segmentation of a patient specific femur from a CT scanPublication . Almeida, D.; Folgado, J.; Fernandes, P.R.; Ruben, RuiThe following paper describes a novel approach to a medical image segmentation problem. The fully automated computational procedure receives as input images from CT scan exams of the human femur and returns a three dimensional representation of the bone. This patient specific iterative approach is based in 3D active contours without edges, implemented over a level set framework, on which the evolution of the contour depends on local image parameters which can easily be defined by the user but also on a priori information about the volume to segment. This joint approach will lead to an optimal solution convergence of the iterative method. The resulting point cloud can be an excellent starting point for a Finite Element mesh generation and analysis or the basis for a stereolitography for example.
- Additive manufactured porous biomaterials targeting orthopedic implants: A suitable combination of mechanical, physical and topological propertiesPublication . Bartolomeu, F.; Dourado, N.; Pereira, F.; Alves, N.; Miranda, G.; Silva, F. S.Orthopedic implants are under incessant advancement to improve their interactions with surrounding bone tissue aiming to ensure successful outcomes for patients. A successful biological interaction between implant and surrounding bone depends on the combination of mechanical, physical and topological properties. Hence, Ti6Al4V cellular structures appear as very promising solutions towards the improvement of conventional orthopedic implants. This work addresses a set of fundamental tools that allow improving the design of Ti6Al4V cellular structures produced by Selective Laser Melting (SLM). Three-point bending tests were carried out to estimate the elastic modulus of the produced structures. Morphological analysis allowed to evaluate the dimensional differences that were noticed between the model CAD and the SLM structures. Finite element models (adjusted CAD) were constructed with the experimentally obtained dimensions to replicate the mechanical response of the SLM structures. Linear correlations were systematically found for the dimensions of the SLM structures as a function of the designed model CAD dimensions. This has also been observed for the measured porosities as a function of the designed CAD models. This data can be used in further FE analyses as design guidelines to help engineers fabricating near-net-shape SLM Ti6Al4V cellular structures. Besides, polished and sandblasted surface treatments performed on the Ti6Al4V cellular structures allowed to obtain suitable properties regarding roughness and wettability when compared to as-produced surfaces. The capillarity tests showed that all the analyzed Ti6Al4V structures are able to transport fluid along its structure. The cell viability tests demonstrate Ti6Al4V cellular structures SLM produced did not release toxic substances to the medium, indicating that these structures can assure a suitable environment for cells to proliferate and attach. This study proposes a design methodology for Ti6Al4V cellular structures, that owe suitable mechanical properties but also provide a proper combination of porosity, roughness, wettability, capillarity and cell viability, all of them relevant for orthopedic applications. A Ti6Al4V cellular structured hip implant prototype gathering the suitable features addressed in this study was successfully SLM-produced.
- Alternative heavy tailed models in seismologyPublication . Felgueiras, Miguel; Martins, João; Santos, RuiGreat earthquakes are commonly considered as the ones with moment magnitude (Mw ) above or equal to 8.0. Since these earthquakes can destroy entire communities located near the epicentre, the search of physical laws that explain the energy released by them is an important issue. There is a connection between the radiated energy of an earthquake, its magnitude and its seismic moment (M 0). Thence, when fitting a heavy or an extremely heavy tailed distribution to a seismic moment dataset, we are in fact adjusting a mathematical model which explains the amount of energy released by these great seisms. Therefore, the main goal of this work is to study the more appropriated Pareto based models (the most used family in this field) when explaining the seismic moment of the great earthquakes. With this purpose in mind, we selected two different catalogs that accommodate recent events and are considered more accurate than other catalogs used in previous works. We conclude that the traditional Pareto distribution remains a good choice to deal with this kind of data, but Log-Pareto lead to higher p-values and Location-scale Pareto is better fitted to the biggest events.
- Atitudes e Comportamentos de Separação de Embalagens Usadas na Comunidade Intermunicipal da Região de LeiriaPublication . Fernandes, Maria Eduarda; Gomes da Silva, Carlos; Gaspar Ferreira, Alcina; Febra, Lígia; Maurício Costa, JoãoA Comunidade Intermunicipal da Região de Leiria (CIMRL) é composta por 10 Municípios, com cerca de 287 mil habitantes (INE, 2022) e recolhe anualmente 123 022 toneladas de resíduos sólidos urbanos, dos quais apenas 17% são recolhidos de forma seletiva (INE, 2025). Neste contexto, e enquadrado no Projeto Embalagem do Futuro (PPS08), é importante compreender melhor os comportamentos e atitudes dos agregados familiares da CIMRL face à separação de embalagens usadas (plástico, metal/alumínio, vidro, cartão/papel e cápsulas de café). Tendo por base a Theory of Planned Behavior, uma das principais teorias usadas para compreender a complexidade do comportamento social humano, as normas morais e os valores pro-ambientais, foi realizado um inquérito online junto dos agregados familiares da CIMRL.
- An automated system for 3D printing functionally graded concrete-based materialsPublication . Craveiro, Flávio; Nazarian, Shadi; Bartolo, Helena; Bartolo, Paulo Jorge; Duarte, José PintoIn recent years, the interest in developing additive manufacturing (AM) technologies in the architecture, engineering and construction (AEC) industry has increased, motivated by the potential to support greater formal complexity. In this context, AM has been largely used to design and fabricate physical parts with homogeneous materials. This paper proposes a new strategy, aimed at the design and fabrication of functionally graded concrete parts with specific thermo-mechanical performance. The paper describes the development of the AM system to materialize such parts. The computational tool developed to design the material to meet specific performance requirements, and the design and testing of the material are described elsewhere. A functionally graded concrete part obtained by replacing sand with cork was produced and is evaluated.
- Biofuel for the energy efficiency on a building with small CCHPPublication . Galvão, João; Leitão, S.; Malheiro, S.; Gaio, T.This document reports the development of a technical and economical study related to the use of a renewable energy source - biomass for electricity and heat production. It is a hybrid and autonomous system with solar PV panels and environment friendly process aiming the reduction of energy demand, costs and emissions. This energy model is a new sustainable standard about efficiency consumption energy (electrical and thermal demands) of a small hotel building, with the biomass gasification cogeneration technology. This system is one relevant contribute to certify the building agree to the new national legislation of building thermal behaviour.
- Biomanufacturing for tissue engineering: Present and future trendsPublication . Bartolo, Paulo; Chua, C. K.; Almeida, Henrique de Amorim; Chou, S. M.; Lim, A. S. C.Tissue engineering, often referred to as regenerative medicine and reparative medicine, is an interdisciplinary field that necessitates the combined effort of cell biologists, engineers, material scientists, mathematicians, geneticists, and clinicians toward the development of biological substitutes that restore, maintain, or improve tissue function. It has emerged as a rapidly expanding approach to address the organ shortage problem and comprises tissue regeneration and organ substitution. Cells placed on/or within constructs is the most common strategy in tissue engineering. Successful cell seeding depends on fast attachment of cell to scaffolds, high cell survival and uniform cell distribution. The seeding time is strongly dependent on the scaffold material and architecture. Scaffolds provide an initial biochemical substrate for the novel tissue until cells can produce their own extra-cellular matrix (ECM). Thus scaffolds not only define the 3D space for the formation of new tissues, but also serve to provide tissues with appropriate functions. These scaffolds are often critical, both in vivo (within the body) or in vitro (outside the body) mimicking in vivo conditions. Additive fabrication processes represent a new group of non-conventional fabrication techniques recently introduced in the biomedical engineering field. In tissue engineering, additive fabrication processes have been used to produce scaffolds with customised external shape and predefined internal morphology, allowing good control of pore size and pore distribution. This article provides a comprehensive state-of-the-art review of the application of biomanufacturing additive processes in the field of tissue engineering. New and moving trends in biomanufacturing technologies and the concept of direct cell-printing technologies are also discussed.
- Building Strategic Capabilities in Brazilian FirmsPublication . Fleury, Maria Tereza Leme; Calixto, Cyntia Vilasboas; Frias Pinto, Cláudia Sofia; Fleury, AfonsoIn this chapter, we highlight the strategic capabilities that have enabled six Brazilian companies to achieve competitive advantage. We selected firms from different industries and stages of internationalization in order to show a broad perspective of local and international successful firms. WEG and Fanen developed technological capabilities associated to both world-class manufacturing and product innovation, whereas Stefanini and Integration have consolidated knowledge about servicing emerging markets. Grendene’s production and operations are its key capabilities for international operations through exports, while innovative design and processes support their strategy in the local markets. The key capabilities of Dr.Consulta are entrepreneurship and innovation. In sum, due to highly turbulent institutional and economic environment, Brazilian firms have had to develop some specific capabilities, especially those related to financial management and organizational flexibility.
- Cancellative conjugation semigroups and monoidsPublication . Garrão, A. P.; Martins-Ferreira, Nelson; Raposo, M.; Sobral, M.We show that the category of cancellative conjugation semigroups is weakly Mal’tsev and give a characterization of all admissible diagrams there. In the category of cancellative conjugation monoids we describe, for Schreier split epimorphisms with codomain B and kernel X, all morphisms h: X→ B which induce a reflexive graph, an internal category or an internal groupoid. We describe Schreier split epimorphisms in terms of external actions and consider the notions of precrossed semimodule, crossed semimodule and crossed module in the context of cancellative conjugation monoids. In this category we prove that a relative version of the so-called “Smith is Huq” condition for Schreier split epimorphisms holds as well as other relative conditions.