The accurate description of the nonlinear structural behaviour is an important issue in engineering science. Usually, classic nonlinear theories, such as fracture and damage mechanics, applied to finite element programmes are used to fulfil that purpose. Classic fracture mechanics describes the structural deterioration process by a few discrete cracks. This theory presents good precision for structures with simple geometries, few cracks and homogeneous materials. Classic damage mechanics measures the deterioration process by an internal variable called damage. This theory has been successful in the description of several deterioration mechanisms in continuum media. Despite their accuracy, classic fracture and damage mechanics present some drawbacks. Firstly, regarding civil engineering problems, both theories are not suitable for some practical applications. Secondly, fracture mechanics demands the consideration of initial cracks to begin the analysis. Lastly, classic damage models may present an issue known as localisation, what essentially leads to ill-posed problems and mesh-dependent numerical algorithms. Alternatively, a recent theory, called lumped damage mechanics, was proposed in order to achieve good accuracy in actual engineering problems. Such theory applies key concepts from fracture and damage mechanics in plastic hinges. In the light of the foregoing, the main goal of this thesis is the extension of the lumped damage mechanics framework to analyse different engineering problems. So far, lumped damage mechanics was characterised as a simplified methodology to analyse reinforced concrete frames under seismic and monotonic loadings; even with a few contributions on the analysis of local buckling in metallic structures. Therefore, this work extends the lumped damage mechanics framework to analyse reinforced concrete arches, unreinforced concrete structures, high cycle fatigue and continuum problems. The application examples show the accuracy of the proposed methodologies. / A descrição acurada do comportamento não linear de estruturas é um problema importante na engenharia. Usualmente, teorias não lineares clássicas, tais como as mecânicas da fratura e do dano, aplicadas a programas de elementos finitos são utilizadas a fim de cumprir aquele propósito. A mecânica da fratura clássica descreve o processo de deterioração estrutural por meio de um pequeno número de fissuras discretas. Esta teoria apresenta boa precisão para estruturas com geometrias simples, poucas fissuras e materiais homogêneos. A mecânica do dano clássica tem sido exitosa na descrição de diversos mecanismos de deterioração em meios contínuos. Apesar de precisas, as abordagens clássicas em fratura e dano apresentam alguns entraves. Primeiramente, tratando-se de problemas da engenharia civil, ambas teorias não são adequadas para aplicações práticas. Em segundo lugar, os modelos clássicos de fratura demandam a consideração de fissuras iniciais para iniciar a análise. Por fim, os modelos clássicos de dano podem apresentar um problema conhecido como localização, o que essencialmente implica em problemas mal colocados e algoritmos com dependência de malha. Alternativamente, uma teoria recente, chamada teoria do dano concentrado, foi proposta a fim de obter boa precisão em problemas reais de engenharia. Tal teoria aplica conceitos-chave das mecânicas da fratura e do dano em rótulas plásticas. À luz do exposto, o principal objetivo desta tese é a extensão da teoria do dano concentrado para analisar diferente problemas da engenharia. Até então, a teoria do dano concentrado era caracterizada como uma metodologia simplificada para analisar pórticos de concreto armado sob solicitações monotônicas ou sísmicas; mesmo com algumas poucas contribuições na análise de instabilidade local em estruturas metálicas. Desta forma, este trabalho estende a teoria do dano concentrado a fim de analisar arcos de concreto armado, estruturas de concreto simples, fadiga de alto ciclo e problemas contínuos. Os exemplos de aplicação mostram a acurácia das metodologias propostas.

This thesis work provides an insight into the design of Force-amplifying Compliant Mechanisms (FaCMs) that are integrated with micromachined resonant accelerometers to increase their sensitivity. An FaCM, by mechanically amplifying the inertial force, enhances the shift in the resonance frequency of the beams used for sensing the acceleration whose effect causes an axial force on the beams. An extensive study on different configurations of resonators namely, single beam resonator, single-ended tuning fork (SETF), and double-ended tuning fork (DETF), is carried out to gain insights about their resonant behavior. The influence of the boundary conditions on the sensor’s sensitivity emerged from the study. We found that not only the force-amplification factor but also the multi-axial stiffness of the FaCM and proof-mass influence the resonance frequency of the resonator as well as the bandwidth of the modified sensor for certain configurations but not all. Thus, four lumped parameters were identified to quantify the effectiveness of an FaCM. These parameters determine the boundary condition of the sensing beams and also the forces and the moment transmitted to them. Also presented in this work is a computationally efficient model, called the Lumped Parameter Model (LPM) for evaluation of the sensitivity. An analytical expression for the frequency-shift of the sensing resonator beams is obtained by considering the FaCM stiffness parameters as well as the lumped stiffness of the suspension of the inertial mass. Various FaCMs are evaluated and compared to understand how the four lumped parameters influence the sensor’s sensitivity. The FaCMs are synthesized using topology optimization to maximize the net amplification factor with the volume constraint. One of the FaCMs outperforms the lever by a factor of six. Microfabrication of resonant accelerometer coupled with FaCM and comb-drive actuator is carried out using a silicon-on-insulator process. Finally, the selection map technique, a compliant mechanism redesign methodology is used for enhancing the amplification of FaCMs. This technique provides scope for further design improvement in FaCMs for given sensor specifications.

Atualmente existem diversas aplicações envolvendo estmturas flexíveis, principalmente nos domínios da robótica ou ciência espacial. Geralmente, há a necessidade de projetar controladores para atenuarem, de forma ativa, as vibrações oriundas da ativação dos modos de vibração da estrutura, ativação esta provocada por algum esforço externo. A eficiência do controlador e, conseqüentemente, a sua aplicabilidade na prática dependem fundamentalmente da existência de um modelo dinâmico que seja realista e preditivo. Isto deve-se ao fato de que, significativas diferenças entre o modelo nominal (planta nominal) e a planta física podem fazer com que a lei de controle, projetada para o modelo nominal, leve a dinâmica do sistema em malha fechada à instabilidade. Portanto, dentre as etapas de um projeto envolvendo estruturas flexíveis, a fase de obtenção de um modelo dinâmico é fundamental. Entretanto, ao se realizar uma pesquisa bibliográfica envolvendo estruturas flexíveis, percebe-se um grande número de artigos devotados à teoria de controle, principalmente a partir dos anos oitenta, mas pouco se tem publicado especificamente sobre modelagem. Este foi o principal aspecto motivador da realização da presente dissertação, cujo primeiro objetivo é avaliar diversas técnicas de modelagem dinâmica para um tipo de estrutura que encontra bastante aplicação, principalmente no domínio da robótica flexível. Uma formulação analítica é desenvolvida, sendo determinadas assim as funções de transferência analíticas. Respostas freqüenciais oriundas destas funções de transferência servem de referência no processo de validação dos modelos, obtidos com as técnicas Formalismo Discreto {Lumped Mass Approach), Modos Assumidos e Deformações Polinomiais (derivada do método dos elementos finitos). Ao final, uma aplicação à robótica flexível é analisada sob a ótica da influência da dinâmica do atuador sobre a dinâmica estrutural. / Nowadays, several applications exist involvíng flexible structures, mainly in the domains of robotics or space sciences. Generally, it is necessary to project a control law to attenuate, in an active way, the vibrations originating from the structure modes activation, provoked by some externai effort. The efficiency of the control law, and consequently its practical implementation, depends fimdamentally on the existence of a realistic and predictive dynamic model. This happens because signifícant difFerences among the nominal model and the physical system may exist And so, the control law, projected for the nominal model, can lead the closed loop system to instability. Therefore, in a project involving flexible structures, the obtaining stage of a dynamic model is fundamental. However, when making a bibliographical research involving flexible structures, one noticed a great number of papers that deal with control theory, mainly starting at the eighties, but not many papers have specifícally been published on dynamic modeling. This was the main motivation aspect of the accomplishment of the present work, whose fírst objective is to evaluate several techniques of dynamic modeling for a structure with applications mainly in the domain of flexible robotics. An analytical formulation is developed and so, analytical transfer functions are determinated. Frequency responses obtained fi-om these transfer functions are references in the validation process of the models, obtained with the techniques Lumped Mass Approach, Assumed Modes and Polynomial Deformations (derived of the finite elements method). At the end, an application to the flexible robotics area is analyzed under the point of view of the actuator dynamics influence on the structural dynamics.

A escassez de dados hidrológicos no Brasil é um problema recorrente em muitas regiões, principalmente em se tratando de dados hidrométricos, produção de sedimentos e qualidade da água. A pesquisa por modelos de bacias hidrográficas tem aumentado nas últimas décadas, porém, a estimativa de dados hidrossedimentológicos a partir de modelos mais sofisticados demanda de grande número de variáveis, que devem ser ajustadas para cada sistema natural, o que dificulta a sua aplicação. O objetivo principal desta tese foi avaliar diferentes ferramentas de modelagem utilizadas para a estimativa da vazão, produção de sedimentos e qualidade da água e, em particular, comparar os resultados obtidos de um modelo hidrológico físico semi-distribuído, o Soil Water Assessment Tool (SWAT) com os resultados obtidos a partir de modelos hidrológicos concentrados, com base na metodologia do número da curva de escoamento do Soil Conservation Service (SCS-CN) e no modelo Generalized Watershed Loading Function (GWLF). Buscou-se avaliar e apresentar em quais condições o uso de cada modelo deve ser recomendado, ou seja, quando o esforço necessário para executar o modelo semi-distribuído leva a melhores resultados efetivos. Em relação à simulação da vazão, os resultados dos dois modelos foram altamente influenciados pelos dados de precipitação, indicando que existem, possivelmente, falhas ou erros de medição que poderiam ter influenciado negativamente os resultados. Portanto, foi proposto aplicar o modelo semi-distribuído com dados de precipitação interpolados (DPI) de alta resolução para verificar a eficiência de seus resultados em comparação com os resultados obtidos com a utilização dos dados de precipitação observados (DPO). Para simulação da produção de sedimentos, e das concentrações de nitrogênio e fósforo, o SWAT realiza uma simulação hidrológica mais detalhada, portanto, fornece resultados ligeiramente melhores para parâmetros de qualidade da água. O uso do modelo semi-distribuído também foi ampliado para simular uma bacia hidrográfica sob a influência do reservatório, a fim de verificar a potencialidade do modelo para esse propósito. Os modelos também foram aplicados para identificar quais os impactos potenciais das mudanças no uso do solo previstas e em andamento. Os cenários estudados foram: I – cenário atual, II – cenário tendencial, com o aumento da mancha urbana e substituição do solo exposto e de parte da mata nativa por uso agrícola; III – cenário desejável, complementa o crescimento urbano tendencial com aumento de áreas de reflorestamento. As metodologias foram aplicadas em duas bacias hidrográficas localizadas no Sudeste do Brasil. A primeira é a bacia do rio Jacaré-Guaçu, incluída na Unidade de Gerenciamento de Recursos Hídricos 13 (UGRHI-13), a montante da confluência do rio das Cruzes, com uma área de 1934 km2. O segundo caso de estudo, é a bacia do rio Atibaia, inserida na UGRHI-5, tem uma área de 2817,88 km2 e abrange municípios dos estados de São Paulo e Minas Gerais. Como principal conclusão, o desempenho do modelo semi-distribuído para estimar a produção de sedimentos, e as concentrações de nitrogênio e fósforo foi ligeiramente melhor do que as simulações do modelo concentrado SCS-CN e GWLF, mas essa vantagem pode não compensar o esforço adicional de calibrá-lo e validá-lo. / The lack of hydrological data in Brazil is a recurrent problem in many regions, especially in hydrometric data, sediment yield and water quality. The research by simplified models has increased in the last decades, however, the estimation of hydrossedimentological data from these more sophisticated models demands many variables, which must be adjusted for each natural system, which makes it difficult to apply. At times it is necessary to respond quickly without much precision in the results, in these situations, simpler models with few parameters can be the solution. The objective of this research is to evaluate different modelling tools used estimate streamflow, sediments yield and nutrients loads values, and namely to compare the results obtained from a physically-based distributed hydrological model (SWAT) with the results from a lumped hydrological, the Soil Conservation Service (SCS-CN) and the Generalized Watershed Loading Function (GWLF) model. Both models use the curve number (CN) concept, determined from land use, soil hydrologic group and antecedent soil moisture conditions and were run with a daily time step. We are particularly interested in understanding under which conditions the use of each model is to be recommended, namely when does the addition effort required to run the distributed model leads to effective better results. The input variables and parameters of the lumped model are assumed constant throughout the watershed, while the SWAT model performs the hydrological analysis at a small unit level, designated as hydrological response units (HRUs), and integrates the results at a sub-basin level. In relation to the flow simulation, the results of the two models were highly influenced by the rainfall data, indicating that, possibly, faults or measurement errors could have negatively influenced the results. Therefore, it was proposed to apply the distributed model with high-resolution grids of daily precipitation to verify the efficiency of its results when compared to rainfall data. For simulation of sediment, nitrogen and phosphorus, SWAT performs a more detailed simulation and thus provides slightly better results. The use of the SWAT was also extended to simulate the influence of reservoir, in order to verify the potentiality of the model, in relation to the simulation. The models also were used to identify which are potential impacts of the ongoing land use changes. The scenarios were: I - Current scenario, II - trend scenario, with the increase of urban land and replacement of the exposed soil and part of the native forest by agricultural use; III - desirable scenario complements the trend urban growth with the replacement of exposed soil and part of the agricultural use by reforestation. The methodologies were applied on two watersheds located in the Southeast of Brazil. The first one is the Jacaré-Guaçu river basin, included in the Water Resources Management Unit 13 (UGRHI-13), upstream of Cruzes river confluence, with an area of 1934 km2. The second watershed is the Atibaia River Basin, a part of Water Resources Management Unit 5 (UGRHI-5). It has an area of 2817.88 km2 and covers municipalities of the states of São Paulo and Minas Gerais.

Enterprising technologies and policies that focus on energy reduction in buildings are paramount to achieving global carbon emissions targets. Energy retrofits, building stock modelling, heating, ventilation, and air conditioning (HVAC) upgrades and demand side management all present high leverage opportunities in this regard. Advances in computing, data science and machine learning can be leveraged to enhance these methods and thus to expedite energy reduction in buildings but challenges such as lack of data, limited model generalizability and reliability and un-reproducible studies have resulted in restricted industry adoption. In this thesis, rigorous and reproducible studies are designed to evaluate the benefits and limitations of state-of-the-art machine learning and statistical techniques for high-impact applications, with an emphasis on addressing the challenges listed above. The scope of this work includes calibration of physics-based building models and supervised deep learning, both of which are used to estimate building properties from real and synthetic data. • Original grey-box methods are developed to characterize physical thermal properties (RC and RK)from real-world measurement data. • The novel application of supervised deep learning for thermal property estimation and HVAC systems identification is shown to achieve state-of-the-art performance (root mean squared error of 0.089 and 87% validation accuracy, respectively). • A rigorous empirical review is conducted to assess which types of gray and black box models are most suitable for practical application. The scope of the review is wider than previous studies, and the conclusions suggest a re-framing of research priorities for future work. • Modern interpretability techniques are used to provide unique insight into the learning behaviour of the black box methods. Overall, this body of work provides a critical appraisal of new and existing data-driven approaches for thermal property estimation in buildings. It provides valuable and novel insight into barriers to widespread adoption of these techniques and suggests pathways forward. Performance benchmarks, open-source model code and a parametrically generated, synthetic dataset are provided to support further research and to encourage industry adoption of the approaches. This lays the necessary groundwork for the accelerated adoption of data-driven models for thermal property identification in buildings. / Graduate

The aim of The Diploma Thesis was to compile a conceptual rainfall-runoff model, that would be eligible to model discharge in conditions of climate changes. After thorough verifications of possible variants, user program Runoff Prophet that is eligible to simulate discharge in closing profile of any river basin was compiled within this paper. Runoff Prophet is deterministic lumped model with monthly computation time step and from the hydrologic phenomena it takes soil moisture, evapotranspiration, groundwater flow and the watercourse flow into account. Its calibration is based on the differential evolution principle with Nash–Sutcliffe model efficiency coefficient as the calibration criterion. Developed software was tested on Vír I. catchment basin and the results of this probe were evaluated from viewpoints of air temperature, precipitation and discharge characteristics in the Dalečín measurement river cross section in distant future according to A1B SRES climate scenario, implemented in LARS-WG weather generator.

The Hybrid Norwood (HN) is a relatively new first stage procedure for neonates with Hypoplastic Left Heart Syndrome (HLHS), in which a sustainable univentricular circulation is established in a less invasive manner than with the standard procedure. A computational multiscale model of such HLHS circulation following the HN procedure was used to obtain detailed hemodynamics. Implementation of a reverse-BT shunt (RBTS), a synthetic bypass from the main pulmonary to the innominate artery placed to counteract aortic arch stenosis, and its effects on local and global hemodynamics were studied. A synthetic and a 3D reconstructed, patient derived anatomy after the HN procedure were utilized, with varying degrees of distal arch obstruction, or stenosis, (nominal and 90% reduction in lumen) and varying RBTS diameters (3.0, 3.5, 4.0 mm). A closed lumped parameter model (LPM) for the peripheral or distal circulation coupled to a 3D Computational Fluid Dynamics (CFD) model that allows detailed description of the local hemodynamics was created for each anatomy. The implementation of the RBTS in any of the chosen diameters under severe stenosis resulted in a restoration of arterial perfusion to near-nominal levels. Shunt flow velocity, vorticity, and overall wall shear stress levels are inverse functions of shunt diameter, while shunt perfusion and systemic oxygen delivery correlates positively with diameter. No correlation of shunt diameter with helicity was recorded. In the setting of the hybrid Norwood circulation, our results suggest: (1) the 4.0mm RBTS may be more thrombogenic when implemented in the absence of severe arch stenosis and (2) the 3.0mm and 3.5mm RBTS may be a more suitable alternative, with preference to the latter since it provides similar hemodynamics at lower levels of wall shear stress.

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