Browsing by Author "Gomes, Miguel"
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- Analog flat-level circuit synthesis with genetic algorithmsPublication . Gomes, Miguel; Tavares, Rui; Goes, JoãoThis paper proposes new techniques for automatic simulation-based analog circuit synthesis using genetic algorithms. This is intended to contribute to the set of electronic design automation tools that use genetic algorithms in circuit synthesis, especially those that use the simulator-in-the-loop paradigm. In this study, a genetic algorithm was employed as the generation engine for analog circuits, and variable-length chromosomes were used to describe circuit topology. The entire process is carried out on a flat level (device level), i.e. using the transistor and other elementary devices (e.g. resistors) as the basic elementary blocks. Circuit synthesis is accomplished without any knowledge of previously defined topologies (or analog block cells). Three techniques are presented for analog circuit synthesis that are incorporated in the genetic algorithm, which contribute to its robustness, leading to better and faster results. These techniques can be summarized as follows: 1) adaptive probability of chromosome acceptance, 2) removal of redundant or useless components, and 3) segmented evolution. The automatic process starts with the circuit input and output specifications and proceeds with the evolution of both circuit topology and component sizing. The results shown in this paper include a 40 dB DC gain amplifier, which, when evaluated with SPECTRE/CADENCE 6.0, using a standard 130 nm technology, with a load capacitor of 10 pF, has a gain of 102 V/V, a GBW product of 70 MHz, and a figure of merit of 1436 MHz.pF/mW.
- Arquivo documental: relativo à visibilidade internacional da obra de Pedro CostaPublication . Knight, Ryland Walker; Mendes, João Maria; Bradshaw, Peter; Azalbert, Nicolas; Corless, Kieron; Gomes, Miguel; Rancière, Jacques; Hasumi, ShigehikoQUAIS SÃO, hoje, as principais características do desenvolvimento de projectos para cinema em Portugal? O que pensam realizadores cinematográficos, produtores, distribuidores e exibidores sobre o cinema português? Que conclusões tirar das suas opiniões, relatos de experiências e análises da situação contemporânea? Que novas tendências surgiram no cinema português, nos primeiros anos do séc. XXI?
- Structural reinforcements on AFO’s: a study using computer aided designing and finite element methodPublication . Gomes, Gonçalo; Lourenço, Inês; Oliveira, José; Gomes, Miguel; Vale, Alberto; Policarpo, Hugo; Quental, Paulo; Freire, Luís; Matos, José PedroAs state by the literature, is usual for thermoplastic AFO’s to open cracks as result of the undergoing stress forces of human gait. That mechanical stress forces trigger fractures areas on critical points, normally near the malleoli (see the picture below), as result as the range of movement of that specific region. David Showers and Lair David, claim that is possible to increase AFO’s resistence trough the inclusion of reinforcements (by waving the plastic) at the retromalleolar area. The purpose of this study is to verify the influence of the application of structural reinforcements has on the distribution of tension and deformation in an AFO in the stance phase of gait.
- Structural reinforcements on AFO's: a study using computer-aided design and finite element methodPublication . Gomes, Gonçalo; Lourenco, Inês; Oliveira, José; Gomes, Miguel; Vale, Alberto; Freire, Luís; Quental, Paulo; Policarpo, Hugo; Matos, José PedroThe opening of cracks on the lateral sides of AFO's is a common problem due to the stress forces applied during the gait cycle. The problem can usually be prevented with the inclusion of structural reinforcements in the expected cracking zone of the AFO. This study proposes an approach to evaluate the effect of the applied reinforcements to the AFO's, quantifying the stress forces and deformation experienced by the orthotic device during the stance phase of the gait. For that, a CAD file of an AFO had to be crated and then edited using CAD software (ANSYS® SpaceClaim® Direct Modeler™) in order to create a geometry suitable to be analyzed by a CAE software (ANSYS® Workbench™™ with the Finite Element Method (FEM). Besides the digital model, different input conditions, such as forces (for dynamic conditions), supports (for static conditions) and material properties were defined and analyzed.
- The disclosure of materiality in the non-financial: reporting of listed European entitiesPublication . Gomes, Miguel; Albuquerque, Fábio; Rodrigues, Maria Albertina BarreiroMateriality is a crucial concept in accounting and auditing, allowing relevant matters to be determined from the perspective of the entity and its stakeholders. With the issuance of recent European Directives on sustainability, new issues have been emerging in regard to what concerns its definition and scope within the entities’ non financial information (NFI) reporting. This exploratory study addresses, through the lens of institutional theory, an objective linked to disclosures about materiality in NFI reporting, assessing this information with a breakdown by industry and country. The study adopts archival research as a method and content analysis as an investigation technique, using as a source different consolidated NFI reports (reports and accounts, sustainability, and integrated reports) relating to the year 2021 from the entities that make up the main indices of Euronext countries. Overall, the findings do not show a high disclosure level on the issues related to materiality, which means that a reduced level of transparency was found in the European entities’ NFI reporting. Moreover, the findings do not support significant differences by country and industry. The study is pertinent in the context of the discussion about the content of disclosure of materiality in the NFI report. In addition, it assumes particular importance due to the diversity of topics addressed related to materiality in NFI reporting, making it relevant for standardization bodies, regulators, auditors, and different stakeholders of NFI reporting. As far as the authors are concerned, this is the first research that assesses the disclosure of materiality in NFI reporting, covering multiple European countries and industries.