ENIDH - EMM - Comunicações, Congressos, Seminários, Encontros, etc.
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- Production of extracts from preserved olives using supercritical CO2 and preliminary evaluation of its polyphenol contentPublication . Cebola, Maria João; Rijo, PatriciaThe supercritical fluid extraction (SFE) technique was used to obtain extracts from a sample simulating an olive pomace, obtained from preserved olives. The objective was to achieve the extraction of polyphenolic components from this matrix which is considered a hazardous waste from the production of olive oil. The supercritical fluid used was carbon dioxide and the SFE studies were conducted in two stages, the first at a pressure of 200 bar and 40 ºC and the second stage at 300 bar, 45 ºC and using ethanol as co-solvent. In both cases the SFE was performed for 3 hours. The first stage was carried out to obtain a cleaner matrix and the second step was aimed at the components of interest. The overall mass yield obtained was 5.5 %. Preliminary HPLC screening of the samples obtained and also of the water in which the olives were preserved showed that the polyphenol compounds were mostly in the latter.
- Uplink Performance Evaluation of Broadband Systems which Adopt a Massive MU-MIMO ApproachPublication . Torres, Paulo; Charrua, Luis; Gusmão, AntonioThis paper deals with an Orthogonal Frequency Division Multiplexing (OFDM)-based uplink within a Multi User (MU)-Multi-Input Multi-Output (MIMO) system where a ”massive MIMO” approach” is adopted. In this context, either an optimum Minimum Mean-Squared Error (MMSE) linear detection or a reduced-complexity Matched Filter (MF) linear detection are considered. Regarding performance evaluation by simulation, several semi-analytical methods are proposed: one performance evaluation method in the optimum (MMSE) case; two performance evaluation methods in the MF case. This paper includes performance results for uncoded 4-Quadrature Amplitude Modulation (QAM)/OFDM transmission and a MUMIMO channel with uncorrelated Rayleigh fading, under the assumptions of perfect power control and perfect channel estimation. The accuracy of performance results obtained through the semi-analytical simulation methods is assessed by means of parallel conventional Monte Carlo simulations [10]. The performance resultsare discussed indetail andwe also emphasize the achievable ”massive MIMO” effects, even for the reducedcomplexity detection techniques, provided that the number of BS antennas is much higher than the number of antennas which are jointly employed in the terminals of the multiple autonomous users.
- Layerwise mixed least-squares finite element models for free vibration analysis of multilayered piezoelectric composite platesPublication . Mesquita, Teresa; Moleiro, Filipa; Araujo, A. L.; Soares, C. M.Mota; Soares, C. A. MotaThis work provides an assessment of a finite element model based on layerwise mixed formulation using least squares applied to plate sandwich structures with skins made of piezoelectric layers and the core with composite angle play laminate layers. The extension to free vibration analysis is developed. The model assumes a layerwise variable description of displacements, transverse stresses and in-plane strains, taken as independent variables. The layerwise mixed formulation enables the fulfilment of the so-called C0z, yielding, for free vibration analysis a symmetric quadratic eigenvalue problem. The present model has nine degrees of freedom(dof ) per node in the core and in the upper and lower piezoelectric skins thirteen (nine to mechanical and four electrical) per node. The numerical examples show that the model predictive capabilities are in excellent agreement with three-dimensional exact solutions and also with available alternative models, from very thick to very thin sandwich piezoelectric plates.
- Information Sharing Performance Management A Semantic Interoperability Assessment in the Maritime Surveillance DomainPublication . Marques, F. S. Bryton Dias; Martínez Marín, J. E.; Delgado Ortega, O.Information Sharing (IS) is essential for organizations to obtain information in a cost-effective way. If the existing information is not shared among the organizations that hold it, the alternative is to develop the necessary capabilities to acquire, store, process and manage it, which will lead to duplicated costs, especially unwanted if governmental organizations are concerned. The European Commission has elected IS among public administrations as a priority, has launched several IS initiatives, such as the EUCISE2020 project within the roadmap for developing the maritime Common Information Sharing Environment (CISE), and has defined the levels of interoperability essential for IS, which entail Semantic Interoperability (SI). An open question is how can IS performance be managed? Specifically, how can IS as-is, and to-be states and targets be defined, and how can organizations progress be monitored and controlled? In this paper, we propose 11 indicators for assessing SI that contribute to answering these questions. They have been demonstrated and evaluated with the data collected through a questionnaire, based on the CISE information model proposed during the CoopP project, which was answered by five public authorities that require maritime surveillance information and are committed to share information with each other.
- Buckling and Geometrically Nonlinear Analysis of Sandwich StructuresPublication . Moita, J. S.; Araújo, A. L.; Correia, Victor M. Franco; Soares, C. M. Mota; Soares, C. A. MotaIn this work a finite element model is presented for buckling and nonlinear analysis of multilayer sandwich plates and shells, with a soft core sandwiched between stiff elastic layers. The finite element is obtained by assembling all element-layers through the thickness using specific assumptions on the displacement continuity at the interfaces between layers, but allowing for different behaviors of the layers. The stiff elastic layers are modelled using the classic plate theory and the core is modelled using Reddy׳s third order shear deformation theory. The present finite element model is a non-conforming triangular plate/shell element with 24 degrees of freedom for the generalized displacements. This model is applied in the solution of illustrative examples and the results are presented and discussed.
- Deformation prediction of composite specimens subjected to three-point bending testsPublication . Monte, Sara M. C.; Infante, Vírginia; Moleiro, F.; Madeira, J. F. A.A computational and experimental study was carried out in order to determine the deformations of specimens made in laminated composite material when subjected to three - point bending test. The specimens were produced using unidirectional carbon fiber prepreg with different aspect ratios and different lamination schemes. The experimental deformations of the bending tests were obtained using an innovative method called digital image correlation. At the computational level, two models were compared: the first developed in ANSYS and the second, not available in any commercial program, developed by MOLEIRO, 2010.The latter presents a mixed Layerwise formulation that assumes displacements and transverse stresses as independent variables, and therefore is able to a priori fulfill the interlaminar continuity C^0 of tranverse stresses and displacements. ANSYS model uses a solid element, in the laminated structural version, and assumes a displacement formulation. It was concluded that the ANSYS model results are more similar to the experimental results of longer specimens and the Layerwise mixed model results are more similar to the experimental results of shorter specimens.
- Computers and StructuresPublication . Camotin, C.; Basaglia, C.; Madeira, J. F. Aguilar; Pina, H.; Ilanko, S.; Kennedy, D.; Rabczuk, T.; Soares, C. M. Mota; Araújo, A. L.; Duarte, F. M.; Pallares, L.; Pallares, F. J.; B. H. V.
- Advances in Engineering SoftwarePublication . Madeira, J.F. Aguilar; Camotim, D.; Basaglia, C.; Santos, J.V. Araujo dos; Lopes, H.M.R.; Topping, B. H. V.; Pina, H.; Poroseva, S. V.; Mota, Soares, C. M.; Araújo, A. L.; Moleiro, Duarte, F.; Sarrate, J.; Ledoux, F.; Kruis, J.; Dumont, S.; Lebon, F.
- Ensemble fuzzy models in personalized medicine: Application to vasopressors administrationPublication . Salgado, Cátia M.; Vieira, Susana M.; Mendonça, Luís; Finkelstein, Stan; Sousa, João M.C.Vasopressors administration in intensive care units is a risky surgical procedure that can be associated with infections, especially if done urgently such as in the case of unexpected systemic shock. The early prediction of a patient׳s transition to vasopressor dependence could improve overall outcomes associated with the procedure. Personalized medicine in the ICU encompasses the customization of healthcare on the level of individual patients, with diagnostic tests, monitoring interventions and treatments being fitted to the individual rather than the “average” patient. In this scope, this paper proposes an ensemble fuzzy modeling approach to a classification problem based on subgroups of patients identified by individual characteristics. A fuzzy c-means clustering algorithm was implemented to find subgroups of patients and each subgroup was used to develop a fuzzy model. The final classification of the ensemble fuzzy approach is obtained using two output selection criteria: an a priori decision criterion based on the distance from the cluster centers to the patients׳ characteristics, and an a posteriori decision criterion based on the uncertainty of the model output. The performance of the proposed approach is investigated using a real world clinical database and nine benchmark datasets. The ensemble fuzzy model approach performs better than the single model for the prediction of vasopressors administration in the ICU, being the a posteriori approach the best performer, with an average AUC of 0.85, showing this way the advantage of a personalized approach for patient care in the ICU.
- Risk Driven Semantic Interoperability in the Maritime Surveillance DomainPublication . Marques, Fernando Sérgio Bryton Dias; Martínez, Jesús; Delgado, Olga; Arriaga, GonzaloSemantic Interoperability (SI) is essential for organizations as to share information, via computer systems, without which their efficiency and effectiveness is hampered. Assuming multiple actions for enhancing SI are possible, and that resources are usually scarce, the more relevant ones should have higher priority. Since information sharing, in the maritime surveillance domain, is essential for dealing with risks, such as irregular migration or piracy, this paper presents a method for prioritizing SI development actions based on the risks they aim to address. The method was developed by following the Design Science Research strategy, is based on the Delphi method and the Weighted Sum Model, and was validated in a real environment, with six organizations involved in maritime surveillance. The method aims to foster information sharing by supporting the development of action plans for enhancing SI, which may deliver relevant results faster, cheaper and less risky than traditional approaches.