Orientador: Waldyr A. Rodrigues Jr / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica / Made available in DSpace on 2018-07-25T01:10:59Z (GMT). No. of bitstreams: 1 Moya_AntonioManuel_D.pdf: 2371692 bytes, checksum: 27c27783a7dad0ff9575696172177b9e (MD5) Previous issue date: 1999 / Resumo: Desenvolvemos o formalismo Lagrangiano para os chamados campos relativísticos utilizando o cálculo do espaço-tempo, i.e., um cálculo multivetorial baseado na álgebra do espaço-tempo. Derivamos rigorosamente a equação de campo, associada à Lagrangiana para um campo multivetorial (rotor ou spinor), a partir do princípio de mínima ação. Derivamos as fórmulas gerais para os extensores canônicos da energia-momento e do momento angular, e obtemos duas formas equivalentes para os correspondentes teoremas de conservação, com campos multivetoriais (rotores) e campos spinoriais tratados de um modo completamente unificado. Demonstramos que aparte antisimétrica do extensor de energia-momento é de grande importância no tratamento correto do momento angular, ela está relacionada à fonte do spin / Abstract: The Lagrangian formalism for the so-called relativistic fields is developed by using the space-time calculus, i.e., a multivector calculus based upon the space-time algebra. The field equation, associated to the Lagrangian for a multivector field (rotor or spinor), is rigorously derived from the least action principle. The general formulas for the canonical stress-energy and angular-momentum extensors are derived, and two equivalent forms for the corresponding conservation theorems are obtained, with multivector fields (rotors) and spinor fields treated in a unified way. It is demonstrated that the antisymmetric part in the stress-energy extensor is potentially important to the correct treatment of the angular-momentum, the one is related to the spin source / Doutorado / Fisica-Matematica / Doutor em Matemática Aplicada

Orientador: Sigmar Maurer Deckmann / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-07-26T00:15:19Z (GMT). No. of bitstreams: 1 Marafao_FernandoPinhabel_M.pdf: 4879723 bytes, checksum: d5a15dcd058b323693761e41d6bb0191 (MD5) Previous issue date: 2000 / Resumo: Os recentes trabalhos envolvendo Teorias de Potências Instantâneas têm sido amplamente utilizados na elaboração de técnicas de análise de distúrbios elétricos e controle de dispositivos de condicionamento de energia. Tais teorias têm se mostrado bastante eficazes, particularmente no caso trifásico, no entanto restam algumas dúvidas ou discussões que ainda necessitam de estudos para que soluções definitivas sejam encontradas para casos gerais.O principal objetivo deste trabalho é apresentar duas decomposições de sinais temporais, as quais levam a uma alternativa interessante para o estudo das grandezas elétricas, de forma que permitem a identificação de várias parcelas distintas de tensão, corrente e potência, associando cada uma ao fenômeno físico responsável por sua origem. Espera-se portanto, que as decomposições e a metodologia de cálculo das componentes de potência instantânea apresentadas neste trabalho contribuam para que se encontre uma Teoria de Potências o mais geral e didática possível. Sobre as decomposições, uma permite encontrar a mínima corrente necessária para suprir a potência útil requerida pelas cargas do sistema elétrico, e pode ser aplicada a qualquer tipo de sinal temporal, independentemente de periodicidade, forma de onda, simetria ou número de variáveis. A outra por sua vez, permite separar as parcelas de tensão, corrente e potência de freqüências fundamentais, dos sinais responsáveis por distorção na forma de onda destas grandezas, o qual denominou-se resíduo dos sinais.N o âmbito de qualidade de energia, assunto de extrema importância na recente reformulação do setor elétrico mundial, acredita-se que as definições e discussões tratadas ao longo deste trabalho, possam auxiliar em diversas aplicações para manutenção e monitoração da qualidade da energia elétrica / Abstract: Instantaneous Power Theories have been widely exploited for electrical disturbance analysis and control applied to power conditioning equipment. These theories have shown to be very promising, particularly in the three-phase case, however several questions still require more researches to find definitive solutions in general cases.The main objective of this work is to present two time signal decomposition techniques, which consti-tute an interesting alternative to study electrical signals, allowing to identify voltage, current, and power components, associating each one with the corresponding physical phenomenon responsible for it. The signal decompositions and calculation methodologies presented in this work are intended to contribute for a more comprehensive Power Theory.About the two decompositions, the first one allows to find the minimum current needed to supply the active power required from electrical system loads, and it can be applied to any time function, independently of period, waveform, symmetry, or variables number. The second one allows splitting voltages, currents and power signals into fundamental waves and signals with harmonic and inter-harmonic frequencies. This last part is responsible for waveform distortions of the signals and it was named residual signal.Concerning power quality, a subject of extreme interest in the recent reformulation of worldwide electrical utilities, the definitions and discussion presented in this work are expected to be useful for several applications in order to maintain and monitor the electric power quality / Mestrado / Mestre em Engenharia Elétrica

The co-optimization of energy and reserves has become a standard requirement in integrated markets. This is due to the inverse relationship that exists between energy and reserves. The provision of reserves generally reduces the amount of primary energy a generating unit can produce and vice versa. This suggests that these products should be procured through a simultaneous auction to ensure optimal procurement and pricing. Furthermore, forward markets dictate that this co-optimization of energy and reserves be done over a multi-period planning horizon. This dissertation addresses the problem of optimal scheduling and pricing of energy and reserves over a multi-period planning horizon using an optimal power flow formulation. The extension of the problem from a static optimization problem to a dynamic optimization problem is presented. Price definitions for energy and reserves in terms of shadow prices emanating from the optimization algorithm are provided. It is shown that the proposed formulation of prices leads to the cascading of reserve prices and eliminates the problem of “price reversal” where lower quality reserves are priced higher than higher ii quality reserves. Pricing conditions are also established for the downward substitution of higher quality reserves for lower quality reserves. The proposed pricing formulations are tested on the IEEE 24 Bus Reliability Test System and on the South African power network. The simulated results show that cascading of reserve prices does occur and that prices of different types of reserves are equal when downward substitution of reserves occurs. Zonal reserve requirements result in higher energy and reserve prices, which in term result in higher procurement costs to the system operator and higher profits to market participants. Congestion on the network also results in higher procurement costs to the system operator and higher profits to market participants in the case of zonal pricing of reserves. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Electrical, Electronic and Computer Engineering / unrestricted

Simulation of mechanical systems like walking robots, is an essential part in developingnew and more applicable solutions in robotics. The increasing complexity of methodsand technologies is a key challenge for common languages. That problem creates a needfor flexible and scalable languages. The thesis concludes that an equation-based toolusing the Euler-Lagrange can simplify the process cycle of modeling and simulation. Itcan minimize the development effort, if the tool supports derivatives. Regretfully, it isnot common to use equation-based tools with this ability for simulation of humanoidrobots.The research in this thesis illustrates the comparison of equation-based tools to commonused tools. The implementation uses the Euler-Lagrange method to model andsimulate nonlinear mechanical systems. The focus of this work is the comparison ofdifferent tools, respectively the development of a humanoid robot in a stepwise mannerbased on the principle of passive walking. Additionally, each developed model has givenan informal argument to its stability. To prove the correctness of the thesis statementthe equation-based tool called Acumen is evaluated in contrast to a common used tool,MATLAB.Based on the achieved results, it can be concluded that the use of equation-based toolsusing Euler-Lagrange formalism is convenient and scalable for humanoid robots. Additionally,the development process is significantly simplified by the advantages of suchtools. Due to the experimental nature of Acumen further research could investigatethe possibilities for different mechanical systems as well as other techniques.

Transformations between different geodetic reference frames are often performed such that first the transformation parameters are determined from control points. If in the first place we do not know which of the numerous transformation models is appropriate then we can set up a multiple hypotheses test. The paper extends the common method of testing transformation parameters for significance, to the case that also constraints for such parameters are tested. This provides more flexibility when setting up such a test. One can formulate a general model with a maximum number of transformation parameters and specialize it by adding constraints to those parameters, which need to be tested. The proper test statistic in a multiple test is shown to be either the extreme normalized or the extreme studentized Lagrange multiplier. They are shown to perform superior to the more intuitive test statistics derived from misclosures. It is shown how model selection by multiple hypotheses testing relates to the use of information criteria like AICc and Mallows’ Cp, which are based on an information theoretic approach. Nevertheless, whenever comparable, the results of an exemplary computation almost coincide.

Orientadores : Sigmar S. Deckmann, Secundino Soares Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Campinas / Made available in DSpace on 2018-07-16T23:58:24Z (GMT). No. of bitstreams: 1 SantosJunior_Anesiodos_D.pdf: 4659046 bytes, checksum: a91d359ef606e9cab35a169504e5a52b (MD5) Previous issue date: 1986 / Resumo: Neste trabalho o problema do fluxo de carga ótimo é resolvido pelo método da lagrangeana aumentada. Os métodos da lagrangeana aumentada, dual clássico e de penalidades são apresentados com uma abordagem unificada. São descritas as características de modelagem utilizadas em um programa computacional desenvolvido tendo em vista a aplicação no planejamento da operação de sistemas de energia elétrica. Os resultados apresentados indicam que o método utilizado é uma boa alternativa para o cálculo do fluxo de carga ótimo / Abstract: In this work the optimal power flow problem solved by an augmented lagrangian method. Augmented lagrangian, classical dual and penalty methods are presented with a unified approach. The modelling characteristics are described as used in a computer program for application on operation planning of electrical energy systems. The results indicate that the method used is a good alternative for optimal power flow solutions / Doutorado / Doutor em Engenharia Elétrica

Una nueva aproximación euleriana-lagarangiana, en su forma de acople en dos vías, para la simulación de flujo de burbujas, agua-aire es presentada en la tesis, en la que se incluyen los efectos de las colisiones entre burbujas, así como las posibles roturas o coalescencia de burbujas. Esta aproximación utiliza el modelo Continuous Random Walk, CRW, para tener en cuenta las fluctuaciones de la velocidad. Esta aproximación se enmarca dentro de un modelo de turbulencia k-epsilon para la fase continua del líquido. En esta tesis se estudiarán los métodos para realizar el acople entre ambas aproximaciones, el efecto de la fuerza lift y de la dispersión turbulenta sobre la distribución de la fracción de huecos, así como los modelos de coalescencia y rotura de burbujas que puedan ser empleados en este tipo de aproximación. Se ha partido de un código euleriano para simular la parte continua, y sobre él se ha acoplado la aproximación lagrangiana. Para que ese acople afecte a la fase continua sobre su solver ser han añadido fuentes de momento y turbulencia. Además se ha modificado el volumen computacional de cada celda para que tenga en consideración el volumen ocupado por la fase dispersa. El acople en doble vía hace que los perfiles de velocidad y turbulencia de la fase continua se modifiquen notablemente y que se aproximen a los reales, lo que resulta básico para la correcta simulación de las fuerzas interfaciales. La colisión entre burbujas, y burbujas y pared se ha incluido. Este efecto es necesario como paso previo a incluir los procesos de rotura o coalescencia de burbujas, aunque la colisión en sí tenga efectos limitados en la distribución de la fracción de huecos. El proceso de coalescencia se basa en el modelo de Chester ( 1991 ) , el modelo compara el tiempo de colisión con el tiempo de drenaje de la película entre burbujas para determinar si existe o no coalescencia. El modelo de rotura se basa en el modelo de Martínez-Bazán. Uno de los principales hitos de / Ali Abd El Aziz Essa ., M. (2012). COUPLED LAGRANGE-EULER MODEL FOR SIMULATION OF BUBBLY FLOW IN VERTICAL PIPES CONSIDERING TURBULENT 3D RANDOM WALKS MODELS AND BUBBLES INTERACTION EFFECTS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/18068 / Palancia

Diese Diplomarbeit untersucht die Optimierung eines Mean-Variance Portfolios auf einem vollständigen Markt unter der Bedingung, dass die Insolvenz des Investors ausgeschlossen ist. Hierbei wird die duale Methode (auch Martingalmethode genannt)

Transformations between different geodetic reference frames are often performed such that first the transformation parameters are determined from control points. If in the first place we do not know which of the numerous transformation models is appropriate then we can set up a multiple hypotheses test. The paper extends the common method of testing transformation parameters for significance, to the case that also constraints for such parameters are tested. This provides more flexibility when setting up such a test. One can formulate a general model with a maximum number of transformation parameters and specialize it by adding constraints to those parameters, which need to be tested. The proper test statistic in a multiple test is shown to be either the extreme normalized or the extreme studentized Lagrange multiplier. They are shown to perform superior to the more intuitive test statistics derived from misclosures. It is shown how model selection by multiple hypotheses testing relates to the use of information criteria like AICc and Mallows’ Cp, which are based on an information theoretic approach. Nevertheless, whenever comparable, the results of an exemplary computation almost coincide.

Both optimal disturbances and optimal control are studied by means of numerical simulations for the case of the flat-plate boundary-layer flow. The optimisation method is the Lagrange multiplier technique where the objective function is the kinetic energy of the flow perturbations and the constraints involve the linearised Navier–Stokes equations. We consider both the optimal initial condition leading to the largest growth at finite times and the optimal time-periodic forcing leading to the largest asymptotic response. The optimal disturbances for spanwise wavelengths of the order of the boundary layer thickness are streamwise vortices exploiting the lift-up mechanism to create streaks. For long spanwise wavelengths it is the Orr mechanism combined with the amplification of oblique wave packets that is responsible for the disturbance growth. Control is applied to the bypass-transition scenario with high levels of free-stream turbulence. In this scenario low frequency perturbations enter the boundary layer and streamwise elongated disturbances emerge due to the non-modal growth. These so-called streaks are growing in amplitude until they reach high enough energy levels and breakdown into turbulent spots via their secondary instability. When control is applied in the form of wall blowing and suction, within the region that it is active, the growth of the streaks is delayed, which implies a delay of the whole transition process. Additionally, a comparison with experimental work is performed demonstrating a remarkable agreement in the disturbance attenuation once the differences between the numerical and experimental setup are reduced.