Numerical Method to Predict Void Formation during The Liquid Composite Molding Process

Void formation during the injection phase of the liquid composite molding process can be explained as a consequence of the non-uniformity of the flow front progression. This is due to the dual porosity within the fiber perform (spacing between the fiber tows is much larger than between the fibers within in a tow) and therefore the best explanation can be provided by a mesolevel analysis, where the characteristic dimension is given by the fiber tow diameter of the order of millimeters. In mesolevel analysis, liquid impregnation along two different scales; inside fiber tows and within the open spaces between the fiber tows must be considered and the coupling between the flow regimes must be addressed. In such cases, it is extremely important to account correctly for the surface tension effects, which can be modeled as capillary pressure applied at the flow front. Numerical implementation of such boundary conditions leads to illposing of the problem, in terms of the weak classical as well as stabilized formulation. As a consequence, there is an error in mass conservation accumulated especially along the free flow front. A numerical procedure was formulated and is implemented in an existing Free Boundary Program to reduce this error significantly.

Paleoambiental reconstruction based on mineralogical data of quaternary littoral deposits occuring at Cortegaça and Maceda beaches (Ovar, Portugal)

The main goal of the present work is the use of mineralogical data corresponding to sediment fine fractions (silt and clay) of Quaternary littoral deposits for the definition of a more detailed vertical zonography and to discriminate the most significant morphoclimatic changes concerned with sediment source areas and sediment deposition areas. The analysis of the available mineralogical data reveals a vertical evolution of the mineral composition. The following aspects deserve particular reference: 1) fine fractions (<38 nm) are composed of quartz and phyllosilicates associated to feldspars, prevailing over other minerals; however in certain sections iron hydroxides and evaporitic minerals occur in significant amounts; 2) clay fractions (<2 nm) show a general prevalence of illite associated with kaolinite and oscillations, in relative terms, of kaolinite and illite contents. Qualitative and quantitative lateral and vertical variations of clay and non clay minerals allow the discrimination of sedimentary sequences and the establishment of the ritmicity and periodicity of the morphoclimatic Quaternary episodes that occurred in the Cortegaça and Maceda beaches. To each one of the sedimentary sequences corresponds, in a first stage, a littoral environment that increasingly became more continental. Climate would be mild to cold, sometimes with humidity - aridity oscillations. Warmer and moister episodes alternated with cooler and dryer ones.

Geomorphic dam-break flows. Part II: numerical simulation

Proceedings of the Institution of Civil Engineers - Water Management 163 Issue WM6

Heat recovery from wastewater: numerical modelling of sewer systems

Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, perfil Engenharia Sanitária

Numerical methods and tangible interfaces for pollutant dispersion simulation

Dissertação apresentada para obtenção do Grau de Doutor em Engenharia do Ambiente, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

Characterization and surface reconstruction of objects in tomographic images of composite materials

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

Optimization of breast tomosynthesis image reconstruction using parallel computing

Breast cancer is the most common cancer among women, being a major public health problem. Worldwide, X-ray mammography is the current gold-standard for medical imaging of breast cancer. However, it has associated some well-known limitations. The false-negative rates, up to 66% in symptomatic women, and the false-positive rates, up to 60%, are a continued source of concern and debate. These drawbacks prompt the development of other imaging techniques for breast cancer detection, in which Digital Breast Tomosynthesis (DBT) is included. DBT is a 3D radiographic technique that reduces the obscuring effect of tissue overlap and appears to address both issues of false-negative and false-positive rates. The 3D images in DBT are only achieved through image reconstruction methods. These methods play an important role in a clinical setting since there is a need to implement a reconstruction process that is both accurate and fast. This dissertation deals with the optimization of iterative algorithms, with parallel computing through an implementation on Graphics Processing Units (GPUs) to make the 3D reconstruction faster using Compute Unified Device Architecture (CUDA). Iterative algorithms have shown to produce the highest quality DBT images, but since they are computationally intensive, their clinical use is currently rejected. These algorithms have the potential to reduce patient dose in DBT scans. A method of integrating CUDA in Interactive Data Language (IDL) is proposed in order to accelerate the DBT image reconstructions. This method has never been attempted before for DBT. In this work the system matrix calculation, the most computationally expensive part of iterative algorithms, is accelerated. A speedup of 1.6 is achieved proving the fact that GPUs can accelerate the IDL implementation.

Predictive analytical and numerical modeling for orthogonal cutting

In this thesis, a predictive analytical and numerical modeling approach for the orthogonal cutting process is proposed to calculate temperature distributions and subsequently, forces and stress distributions. The models proposed include a constitutive model for the material being cut based on the work of Weber, a model for the shear plane based on Merchants model, a model describing the contribution of friction based on Zorev’s approach, a model for the effect of wear on the tool based on the work of Waldorf, and a thermal model based on the works of Komanduri and Hou, with a fraction heat partition for a non-uniform distribution of the heat in the interfaces, but extended to encompass a set of contributions to the global temperature rise of chip, tool and work piece. The models proposed in this work, try to avoid from experimental based values or expressions, and simplifying assumptions or suppositions, as much as possible. On a thermo-physical point of view, the results were affected not only by the mechanical or cutting parameters chosen, but also by their coupling effects, instead of the simplifying way of modeling which is to contemplate only the direct effect of the variation of a parameter. The implementation of these models was performed using the MATLAB environment. Since it was possible to find in the literature all the parameters for AISI 1045 and AISI O2, these materials were used to run the simulations in order to avoid arbitrary assumption.

Mathematical and numerical methods for inverse problems using fundamental solutions techniques

Fundação para a Ciência e a Tecnologia - SFRH/BD/27914/2006

Numerical prediction of diffusion and electric field-induced iron nanoparticle transport

Zero valent iron nanoparticles (nZVI) are considered very promising for the remediation of contaminated soils and groundwaters. However, an important issue related to their limited mobility remains unsolved. Direct current can be used to enhance the nanoparticles transport, based on the same principles of electrokinetic remediation. In this work, a generalized physicochemical model was developed and solved numerically to describe the nZVI transport through porous media under electric field, and with different electrolytes (with different ionic strengths). The model consists of the Nernst–Planck coupled system of equations, which accounts for the mass balance of ionic species in a fluid medium, when both the diffusion and electromigration of the ions are considered. The diffusion and electrophoretic transport of the negatively charged nZVI particles were also considered in the system. The contribution of electroosmotic flow to the overall mass transport was included in the model for all cases. The nZVI effective mobility values in the porous medium are very low (10−7–10−4 cm2 V−1 s−1), due to the counterbalance between the positive electroosmotic flow and the electrophoretic transport of the negatively charged nanoparticles. The higher the nZVI concentration is in the matrix, the higher the aggregation; therefore, low concentration of nZVI suspensions must be used for successful field application.

Numerical modelling of compound channel flow

Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/64337/2009 ; projects PTDC/ECM/70652/2006, PTDC/ECM/117660/2010 and RECI/ECM-HID/0371/2012

Intervenção da fisioterapia após ligamentoplastia do LCA

RESUMO: Objectivo: Este estudo teve por objectivo descrever a prática clínica e os resultados da intervenção da fisioterapia, às 6, 12 e 24 semanas, em indivíduos após ligamentoplastia do LCA. Introdução: O sucesso da ligamentoplastia do LCA está directamente relacionado com a reabilitação após a realização da mesma, permitindo ao utente o retorno a um estilo de vida activo. Apesar de se saber que um programa de reabilitação estruturado e baseado na evidência tem um papel fulcral nos resultados após cirurgia, e de existir consenso sobre a efectividade destes programas após a cirurgia, o mesmo não se pode afirmar acerca de quais os melhores componentes que devem fazer parte desse programa. Tendo em conta a heterogeneidade encontrada na literatura, no que diz respeito à nomenclatura utilizada, às diferenças de duração dos protocolos e às variações significativas nas recomendações dos cuidados de reabilitação, torna-se primordial a realização duma caracterização da prática clínica da fisioterapia em indivíduos submetidos a ligamentoplastia em Portugal, e consequentemente, descrever quais os resultados obtidos ao nível da incapacidade funcional, intensidade de dor e percepção global de melhoria. Metodologia: Realizou-se um estudo de série de casos, com uma amostra de conveniência, do tipo não probabilístico, constituída por 14 utentes referidos para 4 clínicas de fisioterapia e para 3 hospitais, e que cumpriam os critérios de inclusão e exclusão estabelecidos. Os utentes foram avaliados em 4 momentos pré-definidos: na 1ª sessão de fisioterapia e às 6, 12 e 24 semanas após cirurgia. Os resultados obtidos após intervenção da fisioterapia foram descritos ao nível da incapacidade funcional, da intensidade da dor e da percepção global de melhoria. Paralelamente realizou-se uma caracterização da prática clínica relativamente às modalidades utilizadas, número de sessões de tratamento e duração do episódio de cuidados. Resultados: Observou-se uma tendência de melhoria ao longo das 24 semanas em todas as dimensões da Knee injury and Osteoarthritis Outcome Score (KOOS) e na Escala Numérica da Dor (END), assim como na percepção de melhoria pelo utente, medida através da Patient Global Impression of Change Scale (PGIC). Às 6 semanas, as melhorias nas variáveis de resultados foram superiores às encontradas às 12 e 24 semanas, ao nível da incapacidade funcional (à excepção das dimensões KOOS – actividades desportivas e de lazer e KOOS - qualidade de vida) e dor. Relativamente à intervenção da fisioterapia observou-se uma grande heterogeneidade nas modalidades e procedimentos utilizados. Em média realizaram-se 58,14 (±14,15) sessões, sendo que 71 foi o número de sessões mais utilizado. Conclusão: Os resultados deste estudo sugerem que apesar da heterogeneidade da prática clínica, a intervenção da fisioterapia proporciona melhorias ao nível da capacidade funcional e da dor, em indivíduos submetidos a ligamentoplastia do LCA e que essas melhorias são percepcionadas pelos participantes como clinicamente importantes. ---------ABSTRACT: Objective: The aim of this study was to describe the clinical practice and the results of physical therapy intervention, at 6, 12 and 24 weeks, in subjects after ACL reconstruction. Introduction: The success of ACL reconstruction is directly related with the rehabilitation after the surgery, allowing the patient to an active lifestyle return. Despite knowing that a rehabilitation program based on evidence and well designed has a key role in the results after surgery, the same cannot be said about what the best components that should make part of this program. Taking into account the heterogeneity found in the literature, whether at the level of the nomenclature used, whether at level of the differences in duration of the protocols, as well as the existence of recommendations of rehabilitative care that present significant variations at the international level, it becomes paramount to achieving a characterization of the clinical practice of physical therapy in subjects after ACL reconstruction in Portugal, and consequently describe the results obtained regarding to functional disability and pain intensity. Methodology: A case series design with a convenience sample of 14 patients referred to 7 different outpatients physical therapy settings, that fulfilled the pre- established inclusion and exclusion criteria. Patients were evaluated in four pre-defined moments: in the first session of physiotherapy and at 6, 12 and 24 weeks after surgery. The results obtained after physiotherapy intervention were described at the level of functional disability, pain and global perception of change. Subsequently, it was proceeded the characterization the practice of physical therapy regarding to the modalities used, the number of treatment sessions and duration of the episode of care. Results: It was found that there was a trend of improvement, clinically important, over the 24 weeks in all dimensions of Knee injury and Osteoarthritis Outcome Score (KOOS) and in the Numerical Pain Rating Scale (NPRS). At 6 weeks, improvements were superior to those found at 12 and 24 weeks, at the level of functional disability (with the exception of the KOOS-sports and recreation function and KOOS-knee related quality of life dimensions) and pain. As regards the intervention of physical therapy found that the heterogeneity encountered both at the level of clinical practice as evidence,are difficult to compare. On average 58,14 (±14,15) sessions were held, with 71 was the most commonly used sessions numbers. Conclusion: The results of this study suggest that in spite of the heterogeneity of clinical practice, physical therapy intervention provides improvements in terms of functional disability and pain in subjects after ACL reconstruction.

Genome-scale metabolic network reconstruction of Polaromonas sp. strain JS666: analysis of cDCE degradation rates and design of experiments for bioremediation improvement

Release of chloroethene compounds into the environment often results in groundwater contamination, which puts people at risk of exposure by drinking contaminated water. cDCE (cis-1,2-dichloroethene) accumulation on subsurface environments is a common environmental problem due to stagnation and partial degradation of other precursor chloroethene species. Polaromonas sp. strain JS666 apparently requires no exotic growth factors to be used as a bioaugmentation agent for aerobic cDCE degradation. Although being the only suitable microorganism found capable of such, further studies are needed for improving the intrinsic bioremediation rates and fully comprehend the metabolic processes involved. In order to do so, a metabolic model, iJS666, was reconstructed from genome annotation and available bibliographic data. FVA (Flux Variability Analysis) and FBA (Flux Balance Analysis) techniques were used to satisfactory validate the predictive capabilities of the iJS666 model. The iJS666 model was able to predict biomass growth for different previously tested conditions, allowed to design key experiments which should be done for further model improvement and, also, produced viable predictions for the use of biostimulant metabolites in the cDCE biodegradation.

Numerical simulation of blast effects on fibre grout RC panels

The main purpose of the present dissertation is the simulation of the response of fibre grout strengthened RC panels when subjected to blast effects using the Applied Element Method, in order to validate and verify its applicability. Therefore, four experimental models, three of which were strengthened with a cement-based grout, each reinforced by one type of steel reinforcement, were tested against blast effects. After the calibration of the experimental set-up, it was possible to obtain and compare the response to the blast effects of the model without strengthening (reference model), and a fibre grout strengthened RC panel (strengthened model). Afterwards, a numerical model of the reference model was created in the commercial software Extreme Loading for Structures, which is based on the Applied Element Method, and calibrated to the obtained experimental results, namely to the residual displacement obtained by the experimental monitoring system. With the calibration verified, it is possible to assume that the numerical model correctly predicts the response of fibre grout RC panels when subjected to blast effects. In order to verify this assumption, the strengthened model was modelled and subjected to the blast effects of the corresponding experimental set-up. The comparison between the residual and maximum displacements and the bottom surface’s cracking obtained in the experimental and the numerical tests yields a difference of 4 % for the maximum displacements of the reference model, and a difference of 4 and 10 % for the residual and maximum displacements of the strengthened model, respectively. Additionally, the cracking on the bottom surface of the models was similar in both methods. Therefore, one can conclude that the Applied ElementMethod can correctly predict and simulate the response of fibre grout strengthened RC panels when subjected to blast effects.

Genetic algorithm for shipping route estimation with long-range tracking data : automatic reconstruction of shipping routes based on the historical ship positions for maritime safety applications

Ship tracking systems allow Maritime Organizations that are concerned with the Safety at Sea to obtain information on the current location and route of merchant vessels. Thanks to Space technology in recent years the geographical coverage of the ship tracking platforms has increased significantly, from radar based near-shore traffic monitoring towards a worldwide picture of the maritime traffic situation. The long-range tracking systems currently in operations allow the storage of ship position data over many years: a valuable source of knowledge about the shipping routes between different ocean regions. The outcome of this Master project is a software prototype for the estimation of the most operated shipping route between any two geographical locations. The analysis is based on the historical ship positions acquired with long-range tracking systems. The proposed approach makes use of a Genetic Algorithm applied on a training set of relevant ship positions extracted from the long-term storage tracking database of the European Maritime Safety Agency (EMSA). The analysis of some representative shipping routes is presented and the quality of the results and their operational applications are assessed by a Maritime Safety expert.