Comparison of Lagrangian Coherent Structures and Relative Dispersion in a Mixing Layer

Thesis (Master's)--University of Washington, 2016-06

Analysis of chaotic instabilities in a rotating body with internal energy dissipation

Melnikov's method is used to analytically predict the onset of chaotic instability in a rotating body with internal energy dissipation. The model has been found to exhibit chaotic instability when a harmonic disturbance torque is applied to the system for a range of forcing amplitude and frequency. Such a model may be considered to be representative of the dynamical behavior of a number of physical systems such as a spinning spacecraft. In spacecraft, disturbance torques may arise under malfunction of the control system, from an unbalanced rotor, from vibrations in appendages or from orbital variations. Chaotic instabilities arising from such disturbances could introduce uncertainties and irregularities into the motion of the multibody system and consequently could have disastrous effects on its intended operation. A comprehensive stability analysis is performed and regions of nonlinear behavior are identified. Subsequently, the closed form analytical solution for the unperturbed system is obtained in order to identify homoclinic orbits. Melnikov's method is then applied on the system once transformed into Hamiltonian form. The resulting analytical criterion for the onset of chaotic instability is obtained in terms of critical system parameters. The sufficient criterion is shown to be a useful predictor of the phenomenon via comparisons with numerical results. Finally, for the purposes of providing a complete, self-contained investigation of this fundamental system, the control of chaotic instability is demonstated using Lyapunov's method.

Anisotropy-based robust performance analysis of finite horizon linear discrete time varying systems

We consider a problem of robust performance analysis of linear discrete time varying systems on a bounded time interval. The system is represented in the state-space form. It is driven by a random input disturbance with imprecisely known probability distribution; this distributional uncertainty is described in terms of entropy. The worst-case performance of the system is quantified by its a-anisotropic norm. Computing the anisotropic norm is reduced to solving a set of difference Riccati and Lyapunov equations and a special form equation.

TEOLOGIA DA PROSPERIDADE: ADAPTAÇÃO DA RELIGIÃO À LÓGICA DA SOCIEDADE DE CONSUMO.

Esta dissertação analisa a Teologia da Prosperidade, especialmente seu poder de adaptar a religião à lógica da sociedade de consumo. Essa teologia surge nos Estados Unidos na década de 1940, consolidando-se rapidamente no meio evangélico, chegou a influenciar inclusive as igrejas denominadas tradicionais. Sua ênfase está na promessa da prosperidade para seus fiéis. A pesquisa pretende descrever as raízes e o contexto do surgimento desta teologia, sua chegada e propagação no Brasil, seus principais expoentes e sua apropriação pelas igrejas neopentecostais. A suspeita que orienta a pesquisa é a de que o êxito da Teologia da Prosperidade se deve à sua capacidade de adaptar a religião à lógica da sociedade de consumo.

PARA UMA PAZ SEM FIM : Um estudo, sócio-político e teológico, da tipologia messiânica nas perícopes de Isaías 7,10-17 e 8,23-9,6.

O ato de ungir, do qual se origina o termo messias, era um costume dos povos do Antigo Oriente Médio e foi assimilado por Israel. O Antigo Testamento, porém, reinterpretou esta unção. Ele atribuiu ao rei, num primeiro momento, o título de ungido, maxiah;. Nesta perspectiva, o rei Davi foi aquele que deu origem à mentalidade messiânica em Israel. E a respeito da teologia messiânica, o profeta Isaías tornou-se um dos seus expoentes. Ele se dirige à classe alta de Jerusalém e propõe um Ungido de Javé em substituição ao rei da casa de Davi. Isto porque, o messianismo também se tornou um movimento de resistência frente a não observância da justiça e do direito, que culmina com a ausência da paz. Nesse sentido, Isaías apresenta também uma nova percepção do messianismo, a saber, uma ruptura com a casa de Davi (7,17). Este messias não estava sob os critérios humanos de um bom rei, forte e guerreiro, mas sob a direção do Espírito de Javé. Por isso, ele poderá ser um messias criança (7,14; 9,5). Esta dissertação tem, portanto, a finalidade de percorrer o caminho do surgimento do ungido, ou do ato de se ungir, até a concepção isaiânica de messias. Esse desenvolvimento mostrará, ao final do trabalho, a tipologia messiânica apresentada pelo profeta Isaías, a partir das perícopes de 7,10-17 e 8,23-9,6.(AU)

AS RELAÇÕES ENTRE O PROGRAMA ESCOLA DA FAMÍLIA E A DEMOCRATIZAÇÃO DO ESPAÇO ESCOLAR: UM OLHAR AUTOBIOGRÁFICO A PATIR DE MINHA ATUAÇÃO COMO EDUCADOR PROFISSIONAL

Este trabalho tem como principal objetivo responder a seguinte questão: Em que medida projetos como o Programa Escola da Família- PEF, contribuem para a democratização do espaço escolar? Para isso buscaremos compreender como funciona o Programa Escola da Família PEF, implantado por iniciativa da Secretaria de Educação do Estado de São Paulo SEE, desde o ano de 2003, em parceria com a Organização das Nações Unidas para a Educação, a Ciência e a Cultura UNESCO até o ano de 2006 e sob responsabilidade, desde então, do Fundo para o Desenvolvimento da Educação FDE. Este estudo será desenvolvido com os seguintes procedimentos metodológicos : a partir de um olhar autobiográfico considerando minha atuação como educador profissional desde o ano de 2007. Análise bibliográfica, análise documental e empírica sobre o PEF; a partir de dados de observações participativa; de documentos sobre o Programa e da análise de entrevistas com dois expoentes da Academia, o Professor Dr. Décio Azevedo Marques de Saes e o Professor Dr. Paolo Nosella. Os entrevistados foram escolhidos por sua filiação teórica na expectativa de que as mesmas se manifestassem nas respostas obtidas, oferecendo assim oportunidade de cotejar pontos de vista fundamentados em referenciais teóricos diferentes.

A IMPORTÂNCIA DA MÚSICA NA FORMAÇÃO DO INDIVÍDUO: UMA REFLEXÃO SOBRE OS OBSTÁCULOS DA DIFUSÃO DA EDUCAÇÃO MUSICAL NO ESPAÇO ESCOLAR

Este trabalho investigou as interações a entre Música e Matemática, considerando experiências e reflexões de expoentes das ciências exatas, que com seus conceitos de intervalo musical, razões e proporções, consonância, harmonia, temperamento, série harmônica, contribuíram para a estruturação arte da música como ciência. Sob a luz dessa ciência da música, mediante análise descritiva de partitura, contou a história de um país que, segundo o P.I.S.A., se manteve no ranking da educação de 2000 a 2012, revelando interdisciplinaridade das ciências e interações dos conceitos de pensamento analógico, preconizados por Levy e Machado e da teoria das inteligências múltiplas de Gardner. E por fim, se propôs a refletir sobre a importância da educação musical na formação do indivíduo e sobre os obstáculos de sua difusão no espaço escolar.

Exploiting uncertainty in nonlinear stochastic control problem

This work introduces a novel inversion-based neurocontroller for solving control problems involving uncertain nonlinear systems which could also compensate for multi-valued systems. The approach uses recent developments in neural networks, especially in the context of modelling statistical distributions, which are applied to forward and inverse plant models. Provided that certain conditions are met, an estimate of the intrinsic uncertainty for the outputs of neural networks can be obtained using the statistical properties of networks. More generally, multicomponent distributions can be modelled by the mixture density network. Based on importance sampling from these distributions a novel robust inverse control approach is obtained. This importance sampling provides a structured and principled approach to constrain the complexity of the search space for the ideal control law. The developed methodology circumvents the dynamic programming problem by using the predicted neural network uncertainty to localise the possible control solutions to consider. Convergence of the output error for the proposed control method is verified by using a Lyapunov function. Several simulation examples are provided to demonstrate the efficiency of the developed control method. The manner in which such a method is extended to nonlinear multi-variable systems with different delays between the input-output pairs is considered and demonstrated through simulation examples.

Two-dimensional viscoelastic discrete triangular system with negative-stiffness components

Potential applications of high-damping and high-stiffness composites have motivated extensive research on the effects of negative-stiffness inclusions on the overall properties of composites. Recent theoretical advances have been based on the Hashin-Shtrikman composite models, one-dimensional discrete viscoelastic systems and a two-dimensional nested triangular viscoelastic network. In this paper, we further analyze the two-dimensional triangular structure containing pre-selected negative-stiffness components to study its underlying deformation mechanisms and stability. Major new findings are structure-deformation evolution with respect to the magnitude of negative stiffness under shear loading and the phenomena related to dissipation-induced destabilization and inertia-induced stabilization, according to Lyapunov stability analysis. The evolution shows strong correlations between stiffness anomalies and deformation modes. Our stability results reveal that stable damping peaks, i.e. stably extreme effective damping properties, are achievable under hydrostatic loading when the inertia is greater than a critical value. Moreover, destabilization induced by elemental damping is observed with the critical inertia. Regardless of elemental damping, when the inertia is less than the critical value, a weaker system instability is identified.

Anomalies in stiffness and damping of a 2D discrete viscoelastic system due to negative stiffness components

The recent development of using negative stiffness inclusions to achieve extreme overall stiffness and mechanical damping of composite materials reveals a new avenue for constructing high performance materials. One of the negative stiffness sources can be obtained from phase transforming materials in the vicinity of their phase transition, as suggested by the Landau theory. To understand the underlying mechanism from a microscopic viewpoint, we theoretically analyze a 2D, nested triangular lattice cell with pre-chosen elements containing negative stiffness to demonstrate anomalies in overall stiffness and damping. Combining with current knowledge from continuum models, based on the composite theory, such as the Voigt, Reuss, and Hashin-Shtrikman model, we further explore the stability of the system with Lyapunov's indirect stability theorem. The evolution of the microstructure in terms of the discrete system is discussed. A potential application of the results presented here is to develop special thin films with unusual in-plane mechanical properties. © 2006 Elsevier B.V. All rights reserved.

A New Approach for Eliminating the Spurious States in Recurrent Neural Networks

As is well known, the Convergence Theorem for the Recurrent Neural Networks, is based in Lyapunov ́s second method, which states that associated to any one given net state, there always exist a real number, in other words an element of the one dimensional Euclidean Space R, in such a way that when the state of the net changes then its associated real number decreases. In this paper we will introduce the two dimensional Euclidean space R2, as the space associated to the net, and we will define a pair of real numbers ( x, y ) , associated to any one given state of the net. We will prove that when the net change its state, then the product x ⋅ y will decrease. All the states whose projection over the energy field are placed on the same hyperbolic surface, will be considered as points with the same energy level. On the other hand we will prove that if the states are classified attended to their distances to the zero vector, only one pattern in each one of the different classes may be at the same energy level. The retrieving procedure is analyzed trough the projection of the states on that plane. The geometrical properties of the synaptic matrix W may be used for classifying the n-dimensional state- vector space in n classes. A pattern to be recognized is seen as a point belonging to one of these classes, and depending on the class the pattern to be retrieved belongs, different weight parameters are used. The capacity of the net is improved and the spurious states are reduced. In order to clarify and corroborate the theoretical results, together with the formal theory, an application is presented.

A multi-modular second life hybrid battery energy storage system for utility grid applications

The modern grid system or the smart grid is likely to be populated with multiple distributed energy sources, e.g. wind power, PV power, Plug-in Electric Vehicle (PEV). It will also include a variety of linear and nonlinear loads. The intermittent nature of renewable energies like PV, wind turbine and increased penetration of Electric Vehicle (EV) makes the stable operation of utility grid system challenging. In order to ensure a stable operation of the utility grid system and to support smart grid functionalities such as, fault ride-through, frequency response, reactive power support, and mitigation of power quality issues, an energy storage system (ESS) could play an important role. A fast acting bidirectional energy storage system which can rapidly provide and absorb power and/or VARs for a sufficient time is a potentially valuable tool to support this functionality. Battery energy storage systems (BESS) are one of a range suitable energy storage system because it can provide and absorb power for sufficient time as well as able to respond reasonably fast. Conventional BESS already exist on the grid system are made up primarily of new batteries. The cost of these batteries can be high which makes most BESS an expensive solution. In order to assist moving towards a low carbon economy and to reduce battery cost this work aims to research the opportunities for the re-use of batteries after their primary use in low and ultra-low carbon vehicles (EV/HEV) on the electricity grid system. This research aims to develop a new generation of second life battery energy storage systems (SLBESS) which could interface to the low/medium voltage network to provide necessary grid support in a reliable and in cost-effective manner. The reliability/performance of these batteries is not clear, but is almost certainly worse than a new battery. Manufacturers indicate that a mixture of gradual degradation and sudden failure are both possible and failure mechanisms are likely to be related to how hard the batteries were driven inside the vehicle. There are several figures from a number of sources including the DECC (Department of Energy and Climate Control) and Arup and Cenex reports indicate anything from 70,000 to 2.6 million electric and hybrid vehicles on the road by 2020. Once the vehicle battery has degraded to around 70-80% of its capacity it is considered to be at the end of its first life application. This leaves capacity available for a second life at a much cheaper cost than a new BESS Assuming a battery capability of around 5-18kWhr (MHEV 5kWh - BEV 18kWh battery) and approximate 10 year life span, this equates to a projection of battery storage capability available for second life of >1GWhrs by 2025. Moreover, each vehicle manufacturer has different specifications for battery chemistry, number and arrangement of battery cells, capacity, voltage, size etc. To enable research and investment in this area and to maximize the remaining life of these batteries, one of the design challenges is to combine these hybrid batteries into a grid-tie converter where their different performance characteristics, and parameter variation can be catered for and a hot swapping mechanism is available so that as a battery ends it second life, it can be replaced without affecting the overall system operation. This integration of either single types of batteries with vastly different performance capability or a hybrid battery system to a grid-tie 3 energy storage system is different to currently existing work on battery energy storage systems (BESS) which deals with a single type of battery with common characteristics. This thesis addresses and solves the power electronic design challenges in integrating second life hybrid batteries into a grid-tie energy storage unit for the first time. This study details a suitable multi-modular power electronic converter and its various switching strategies which can integrate widely different batteries to a grid-tie inverter irrespective of their characteristics, voltage levels and reliability. The proposed converter provides a high efficiency, enhanced control flexibility and has the capability to operate in different operational modes from the input to output. Designing an appropriate control system for this kind of hybrid battery storage system is also important because of the variation of battery types, differences in characteristics and different levels of degradations. This thesis proposes a generalised distributed power sharing strategy based on weighting function aims to optimally use a set of hybrid batteries according to their relative characteristics while providing the necessary grid support by distributing the power between the batteries. The strategy is adaptive in nature and varies as the individual battery characteristics change in real time as a result of degradation for example. A suitable bidirectional distributed control strategy or a module independent control technique has been developed corresponding to each mode of operation of the proposed modular converter. Stability is an important consideration in control of all power converters and as such this thesis investigates the control stability of the multi-modular converter in detailed. Many controllers use PI/PID based techniques with fixed control parameters. However, this is not found to be suitable from a stability point-of-view. Issues of control stability using this controller type under one of the operating modes has led to the development of an alternative adaptive and nonlinear Lyapunov based control for the modular power converter. Finally, a detailed simulation and experimental validation of the proposed power converter operation, power sharing strategy, proposed control structures and control stability issue have been undertaken using a grid connected laboratory based multi-modular hybrid battery energy storage system prototype. The experimental validation has demonstrated the feasibility of this new energy storage system operation for use in future grid applications.