This thesis introduces a comprehensive methodology to improve electromagnetic transient (EMT) modelling of power cables systems. Several improved modelling and validation techniques are proposed at the parameter estimation, time domain simulation and validation stages of the EMT modelling of transmission lines. A novel approach is developed to model sector-shaped cables in electromagnetic transient type programs. First, the applicability of elemental sub-conductor technique is extended to accurately calculate the frequency dependent impedances of sector-shaped cables. The derived admittance and propagation characteristics of the sector-shaped cable are fitted with rational functions using the method of vector fitting in an EMT-type program. The time domain simulations are validated with the numerical inverse Laplace transform method. A novel frequency domain approach is presented to model cascaded transmission systems. The procedure is based on obtaining four composite propagation functions representing the cascaded system. The performance of the technique does not diminish with increased number of cascaded segments and it preserves the intrinsic details of each line segment. This method is capable of modelling cascaded overhead lines or cables with different characteristic admittances and line lengths. This method can be used to validate EMT models of cascaded transmission systems. An improved generalized transmission line model is introduced which is capable of accommodating time steps greater than the travel time of the line. The time step of the conventional EMT models of transmission lines is constrained by the smallest travel time of the line. When the high frequency transients at the line terminations are not of interest, inaccurate nominal π equivalents are used with large time steps to reduce the computational burden. The proposed model not only is more accurate than the π equivalents, but also degenerates to the conventional frequency dependent EMT model when used with time steps smaller than the travel time. Therefore, the proposed model is highly convenient as it can be used for all types of EMT simulations without resorting to nominal π equivalents when the large simulation time steps must be used to reduce computational burden. / February 2017

The generalized data which are presented in this thesis are the culmination of the determination of the foil depression factor using oblate spheroidal coordinates.

HEAT-grenades are wing-stabilized grenades using shaped charge technology. Theshaped charge is a method, producing a jet-beam, with the use of a copper linerin which the aim is to focus the detonation energy to be able to penetrate armourand structures. This jet-beam is only eective under a rotational frequency of 15Hz, any frequency above this and the produced jet-beam loses its eciency and willnot be able to penetrate its target. One approach to minimize the inner body'srotation is by using bearings. By the use of ball bearings the intention is to with-hold transferring the angular momentum from the outer rotating body to the innercylinder body. This thesis have been analysing how much rotation the warhead haveacquired from the outer rotation of the grenade divided in an acceleration phase anda ying phase. During the acceleration phase the rotation of the warhead is reach-ing a frequency of 0.35 Hz. Proposals are presented for improving and lowering therotational speeds for future studies.

Thesis advisor: Lawrence T. Scott / This dissertation describes the work that has been carried out towards accessing a C3v [6,6] nanotube end-cap through rational chemical synthesis. Continued advancement in carbon nanotube research has driven scientists to develop a successful route to usable quantities of nanotubes that are homogeneous in structure. Due to the current inability to separate nanotube mixtures efficiently, researchers in fields ranging from chemistry to computer science have been unable to exploit fully all that these unique molecules have to offer. Our envisioned approach to this obstacle involves elongation of a template endcap using iterative growth chemistry. The final stage of the proposed end-cap synthesis involves the execution of a six fold cyclodehydrogenation reaction. To carry out this desired transformation, a new microwave assisted variant of the anionic cyclodehydrogenation reaction has been developed. Through this chemistry we have been able to access a variety of both known and novel polycyclic aromatic hydrocarbons, often in impressively high yields. We hope that this chemistry will be useful to us in accessing the target nanotube end-caps, and to others in providing a new route to accessing a variety of polycyclic aromatic hydrocarbon cores. / Thesis (PhD) — Boston College, 2008. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Testam-se quatro utilidades com o formato S das curvas de saturação - gama, logística, Cauchy e Cauchy modificada - no modelo básico de apreçamento de ativos de Lucas, com séries temporais do mercado americano. Estabelecendo-se um parâmetro que acompanha o nível de consumo per capita , constata-se que todas resolvem o chamado riskfree puzzle. A gama e a Cauchy modificada saem-se melhor no apreçamento dos 25 ativos do portfolio de Fama e French e esta última é eleita a vencedora, pelas suas propriedades assintóticas e por apresentar coeficiente médio (no sentido cross-section) de aversão relativa ao risco na faixa considerada normal (entre 0 e 5). A Cauchy modificada regulariza a utilidade de Constantinides-Cochrane-Campbel, de formação de hábito, permitindo que o trecho abaixo do consumo habitual seja usado, com isso dispensando o uso de truques para impedir que o consumo suavizado ultrapasse o real. Constatou-se a manutenção daquele coeficiente médio dentro da faixa normal, em um nível pouco abaixo do americano, no caso do mercado brasileiro. Nesse sentido de média crosssection, poderia-se dizer que a utilidade aqui proposta resolve o chamado equity premium puzzle. / Four S-shaped utility functions are tested - gamma, logistic, Cauchy and modified Cauchy - on Lucas asset pricing model with American market time series. Establishing a parameter that follows the level of the per capita consumption, it is shown that all of them solve the so called risk free puzzle. The gamma utility and the modified Cauchy are the ones with better pricing power with respect to Fama and French\'s 25 book-to-market portfolio and the last one is elected the winner, for its asymptotic properties and for exhibiting mean (in the cross-section sense) relative risk aversion coefficient inside the accepted normal range (between 0 and 5). The modified Cauchy utility regularizes the habit-formation Constantinides-Cochrane-Campbel utility function, allowing the usage of the stretch below the habit consumption level, thus doing without the need of tricks to forbid the smoothed consumption series from outgrowing the real one. In the Brazilian market, the mean relative risk aversion coefficient also remains inside the acceptable region, on a slightly lower level. In this mean cross-section sense, it might be possible to state that the utility here proposed solves the equity premium puzzle.

Este trabalho tem como propósito, investigar a validade da lei de Hess-Murray, através da experimentação numérica, aplicando o método do Design Construtal associado ao método de otimização da busca exaustiva, no escoamento interno em estruturas em forma de T com seção circular. Variação do número de Reynolds, escoamento de fluidos newtonianos e não newtonianos, estrutura em forma de T com paredes impermeáveis e permeáveis, foram as principais características avaliadas para confrontar a lei de Hess-Murray. O estudo proposto assume escoamento tridimensional, laminar, incompressível, regime permanente e propriedades fluidodinâmicas constantes, sendo o regime de escoamento governado pelo número de Reynolds (Re). O objetivo principal consiste em determinar as configurações ótimas que facilitem o escoamento de fluido ou minimizem as resistências ao escoamento, quando a área ocupada pelos dutos (A) e o volume ocupado pelos dutos (V) são mantidos constantes, variando-se as razões de diâmetros (aD) e comprimentos (aL). As equações de conservação de massa e quantidade de movimento, foram resolvidas através do método de volumes finitos. A geometria foi discretizada através de uma malha tridimensional composta por aproximadamente 1.950.000 elementos. Como resultados, obteve-se as geometrias ótimas que apresentaram resistências ao escoamento até 30 vezes menor do que as demais configurações. Além disso, foi possível verificar que a lei de Hess-Murray nem sempre é válida, visto que o sistema adapta sua geometria ótima para cada condição de escoamento, a fim de proporcionar a melhor arquitetura de escoamento para atender ao objetivo de minimizar as resistências ao escoamento em acordo com a Lei Construtal. Esta dissertação avançou no presente estado da arte, pois desenvolveu um modelo tridimensional sem simplificações, aplicado ao sistema de escoamento de fluidos em estrutura em forma de T utilizando o método do Design Construtal, validando os resultados analíticos apresentados na bibliografia e apresentando novas referências que permitem ampliar a complexidade dos sistemas de escoamento bem como a implementação de métodos de otimização mais avançados. / This work investigates, through the numerical experimentation together with the Construtal Design method, the Hess-Murray Law in the internal flow in T-shaped structures with a circular section for the laminar flow of Newtonian and non-Newtonian fluids with impermeable and permeable walls, determining the optimal configurations that facilitate fluid flow or minimize flow resistance. The geometric global constants, the volume occupied by the ducts (V) and the area occupied by the ducts (A), delimit the space occupied by the T-shaped structure and the degrees of freedom, the ratio between the diameter of the parent duct and daughter (aD) and the ratio between parent duct length and daughter (aL), are the main geometric parameters to be evaluated. The proposed study is assumed three-dimensional, laminar, incompressible, permanent and constant fluidodynamic properties being the flow regime governed by Reynolds number (Re). Construtal Design method, associated with the exhaustive search, was used to determine the global geometric constants, degrees of freedom and objective function in the geometric evaluation of the system. The numerical solution of the mass conservation and momentum equations is solved based on the finite volume method. The geometries and mesh of the computational domain was discretized through a three-dimensional composed of approximately 1,950,000 elements. The results show that the optimal geometries that presented resistance to the flow up to 30 times smaller than the other configurations. In addition, it was possible to verify that the Hess-Murray Law is not always valid, since the system adapts its optimal geometry to each flow condition, in order to provide a better flow architecture to meet the objective of minimizing resistance to flow in agreement with the Constructal Law. This work advanced in the present state of the art, since it developed a three-dimensional model without simplifications, applied to the fluid flow system in T-shaped structure using the Construtal Design method, validating the analytical results presented in the bibliography and presenting new references that allow increase the complexity of flow systems as well as the implementation of more advanced optimization methods.

Testam-se quatro utilidades com o formato S das curvas de saturação - gama, logística, Cauchy e Cauchy modificada - no modelo básico de apreçamento de ativos de Lucas, com séries temporais do mercado americano. Estabelecendo-se um parâmetro que acompanha o nível de consumo per capita , constata-se que todas resolvem o chamado riskfree puzzle. A gama e a Cauchy modificada saem-se melhor no apreçamento dos 25 ativos do portfolio de Fama e French e esta última é eleita a vencedora, pelas suas propriedades assintóticas e por apresentar coeficiente médio (no sentido cross-section) de aversão relativa ao risco na faixa considerada normal (entre 0 e 5). A Cauchy modificada regulariza a utilidade de Constantinides-Cochrane-Campbel, de formação de hábito, permitindo que o trecho abaixo do consumo habitual seja usado, com isso dispensando o uso de truques para impedir que o consumo suavizado ultrapasse o real. Constatou-se a manutenção daquele coeficiente médio dentro da faixa normal, em um nível pouco abaixo do americano, no caso do mercado brasileiro. Nesse sentido de média crosssection, poderia-se dizer que a utilidade aqui proposta resolve o chamado equity premium puzzle. / Four S-shaped utility functions are tested - gamma, logistic, Cauchy and modified Cauchy - on Lucas asset pricing model with American market time series. Establishing a parameter that follows the level of the per capita consumption, it is shown that all of them solve the so called risk free puzzle. The gamma utility and the modified Cauchy are the ones with better pricing power with respect to Fama and French\'s 25 book-to-market portfolio and the last one is elected the winner, for its asymptotic properties and for exhibiting mean (in the cross-section sense) relative risk aversion coefficient inside the accepted normal range (between 0 and 5). The modified Cauchy utility regularizes the habit-formation Constantinides-Cochrane-Campbel utility function, allowing the usage of the stretch below the habit consumption level, thus doing without the need of tricks to forbid the smoothed consumption series from outgrowing the real one. In the Brazilian market, the mean relative risk aversion coefficient also remains inside the acceptable region, on a slightly lower level. In this mean cross-section sense, it might be possible to state that the utility here proposed solves the equity premium puzzle.

Esta pesquisa investigou microfósseis neoproterozoicos em forma de vaso (\"vase-shaped microfossils - VSMs\") da Formação Urucum (Grupo Jacadigo) e Formação Bocaina (Grupo Corumbá), ambas inseridas na Faixa Paraguai Sul, Brasil. Estes microfósseis foram comparados a outras ocorrências neoproterozoicas no mundo. O objetivo foi contribuir com o conhecimento de aspectos paleobiológicos, evolutivos e bioestratigráficos relacionados ao aparecimento de eucariontes unicelulares tecados em ecossistemas anteriores ao surgimento dos metazoários. Os VSMs podem ser atribuídos a quitinozoários, tintinídeos e foraminíferos, porém, características diagnósticas importantes apontam o grupo Amoebozoa como afinidade biológica mais próxima. A variedade morfológica e composicional observada em VSMs neoproterozoicos, inclusive nos exemplares brasileiros, documenta a mais antiga diversificação da vida unicelular eucariótica, presumivelmente heterotrófica, preservada no registro geológico. As diferentes fácies sedimentares contendo VSMs fornecem informações valiosas sobre fatores ambientais que podem ter sido importantes na diversificação bem como no seu possível desaparecimento entre o Neoproterozoico e o Mesozoico. Além disso, a ampla distribuição e variedade desses microfósseis sugerem uma possível aplicação bioestratigráfica. Microscopia petrográfica (MP) e Eletrônica de Varredura (MEV), Espectrometria de Energia Dispersiva de Raios X (EDS), Microscopia Confocal (MC), Espectroscopia Raman (ER), Catodoluminescência (CL) além de técnicas geoquímicas e geocronológicas foram aplicadas para caracterizar a composição e morfologia dos microfósseis, bem como para a rocha encaixante, visando inferir a natureza e paleoecologia dos organismos responsáveis pelas produção das tecas e o ambiente em que viveram, se diversificaram e desapareceram. / This research investigated vase-shaped microfossils (VSMs) from the Urucum Formation (Jacadigo Group) and Bocaina Formation (Corumbá Group), both inserted in the Southern Paraguay Fold Belt, Brazil. These microfossils were compared to other neoproterozoic occurrences in the world. The aim was to contribute to the knowledge of paleobiological, evolutionary and biostratigraphic aspects related to the appearance of unicellular eukaryotes in the ecosystems that preceed the appearance of metazoans. VSMs can be attributed to quitinozoan, tintinids and foraminifera, but important diagnostic features point to the Amoebozoa group as the closest biological affinity. The morphological and compositional variety observed in neoproterozoic VSMs, including Brazilian specimens, documents the earliest diversification of eukaryotic unicellular life, presumably heterotrophic, preserved in the geological record. The different sedimentary facies containing VSMs provide valuable information about environmental factors that may have been important in the diversification as well as their possible disappearance between the Neoproterozoic to the Mesozoic. In addition, the wide distribution and variety of these microfossils suggest a possible biostratigraphic application. Petrography, Scanning electron microscopy, Confocal microscopy, Energy-dispersive X-ray spectroscopy, Raman spectroscopy, Cathodoluminescense, besides geochemical and geochronological techniques, were applied to characterize the composition and morphology of the microfossils, as well as for the host rock, in order to infer the nature and paleoecology of the organisms responsible for the production of the test and the environment in which they lived, diversified and probably disappeared

Driven by the need to reduce the sound transmitted into aircraft cabins from the power plant, this thesis investigates the active control of sound transmitted through a structure into coupled enclosures. In particular, it examines alternatives to conventional microphone and accelerometer error sensors. This study establishes a design framework for the development and analysis of an active noise control system which can be applied to any complex vibro-acoustic system. The design approach has focused on using techniques presently used in industry to enable the transfer of the active noise control technology from the research stage into practical noise control systems. The structural and acoustic sub-systems are modelled using FEA to estimate the in vacuo structural modal response of the structure and the acoustic pressure modal response (with rigid boundary conditions) of the interior cavity. The acoustic and structural systems are then coupled using modal coupling theory. Within this framework, two novel error sensors aimed at overcoming observability problems suffered by traditional microphone and accelerometer sensors are investigated: namely, acoustic energy density sensors and shaped radiation modal vibration sensors. The principles of the measurement of energy density are discussed and the errors arising from its measurement using two and three-microphone sensor configurations are considered for a one-dimensional reactive sound field and a plane wave sound field. The error analysis encompasses finite separation effects, instrumentation errors (phase and sensitivity mismatches, and physical length errors), diffraction and interference effects, and other sources of error (mean flow and turbulence, temperature and humidity, statistical effects). Following the one-dimensional study, four 3-axis energy density sensor designs are proposed and error analysis is conducted over the same acoustic fields as for the one-dimensional study. The design and construction of the simplest arrangement of the 4 three-axis sensors is discussed with reference to design issues, performance and limitations. The strategy of using energy density control is investigated numerically for a purely acoustic system and a coupled panel-cavity system. Energy density control is shown to provide greater local and global control compared to that possible using an equivalent number of microphones. The performance of the control system is shown to be relatively insensitive to the placement of the energy density sensor. For an enclosed cavity system with high modal overlap, the zone of local control achieved by minimising energy density is found to be approximately the same as the zone of local control obtained when min-imising pressure and pressure gradient in a diffuse sound field. It is also shown that if there is only one control source used per energy density sensor, global control will be almost optimum. The addition of further control sources leads to an improvement in global control, however, the control is no longer optimal. The control system is found to be very tolerant of errors in the estimate of the energy density and thus the use of simpler energy density sensor designs is justified. Finally, an experiment is presented in which the global performance achieved by controlling a three-axis energy density sensor is compared with the performance achieved by minimising the acoustic potential energy and minimising the sum of squared pressures at a finite number of microphones. The experimental results are found to reflect the numerical results. The active minimisation of harmonic sound transmission into an arbitrarily shaped enclosure using error signals derived from structural vibration sensors is investigated numerically and experimentally. It is shown that by considering the dynamics of the coupled system, it is possible to derive a set of "e;structural radiation"e; modes which are orthogonal with respect to the global potential energy of the coupled acoustic space and which can be sensed by structural vibration sensors. Minimisation of the amplitudes of the "e;radiation modes"e; is thus guaranteed to minimise the interior acoustic potential energy. The coupled vibro-acoustic system under investigation is modelled using Finite Element Analysis which allows systems with complex geometries to be investigated rather than limiting the analysis to simple, analytically tractable systems. Issues regarding the practical implementation of sensing the orthonormal sets of structural radiation modes are discussed. Specific examples relating to the minimisation of the total acoustic potential energy within a curved rectangular panel and a coupled cavity are given, comparing the performance offered using vibration sensing of the radiation modes on the structure with the more traditional error sensing; namely, the discrete sensing of the structural kinetic energy on the structural boundary and the acoustic potential energy in the enclosed space approximated by the mean squared pressures at several locations. / Thesis (Ph.D.)--Mechanical Engineering, 1999.

<p>High power impulse magnetron sputtering (HiPIMS) is a novel pulsed power technique. In HiPIMS, high power pulses are applied to the target for short duration with a low duty factor. It provides a high degree of ionization of the sputtered material (in some cases up to 90%) and a high plasma density (10¹⁹ m^-3) which results in densification of the grown films. Recently a large side-transport of the sputtered material has been discovered, meaning that the sputtered material is transported radially outwards, parallel to the cathode surface. In this research, we use this effect and study the side-ways deposition of thin films. We designed a new magnetron sputtering system, consisting of two opposing magnetrons with similar polarity. Ti films were grown on Si using the side-ways transport of the sputtered material. Scanning electron microscope was employed to investigate the microstructure of the grown films. Optical emission spectroscopy (OES) measurements were made for investigating the ionized fraction of the sputtered material while Langmuir probe measurements were made for evaluating the plasma parameters such as electron density. The conclusion is that the system works well for side-ways deposition and it can be useful for coating the interior of cylindrically shaped objects. It is a promising technique that should be used in industry.</p>