<p>Ova doktorska teza analizira problem re&scaron;avanja karakterističnih<br />jednačina, koje se koriste prilikom re&scaron;avanja jednačina svojstvenih<br />oblika, definisanih kroz harmonijski spojen metod konačnih<br />traka. U slučaju složenijih graničnih uslova pokazano<br />je da gre&scaron;ke određivanja korenova karakteristične jednačine rastu<br />gotovo eksponencijalno sa svakim narednim modom, usled<br />prirode s&acirc;mih karakterističnih jednačina. Tako dobijeni korenovi<br />karakteristične jednačine značajno i nepovoljno utiču na<br />tačnost re&scaron;avanja jednačina svojstvenih oblika, izračunavanja<br />određenih integrala, kao i celokupnih proračuna. Predstavljena<br />je hibridna metoda putem koje se na pouzdan nacin određuju<br />korenovi karakterističnih jednačina, re&scaron;avaju jednačine svojstvenih<br />oblika i izračunavaju određeni integrali. Razvijen je<br />prototip referentne Open Source implementacije hibridne metode,<br />uz podsistem za automatsku verifikaciju koji rigorozno<br />verifikuje karakteristike hibridne metode i njene referentne implementacije,<br />za sve navedene granične uslove i integrale.</p> / <p>This PhD thesis analyzes the problem of solving the characteristic<br />equations of the basic functions, as defined by the harmonic<br />coupled finite strip method. It&rsquo;s found that with each increasing<br />mode the characteristic equation root-finding error grows<br />exponentially for all but the most trivial edge boundary conditions,<br />due to the hyperbolic functions involved. These large rootfinding<br />errors will lead to severe accuracy issues when computing<br />basic functions and their integrals, especially for higher modes.<br />A hybrid method for accurately solving characteristic equations<br />and obtaining the required integrals is presented, along with its<br />reference Open Source implementation. An extensive test suite<br />has been developed to verify the hybrid method and its implementation<br />for all the presented boundary conditions and integrals.</p>

The objectives of this work were to investigate, design and implement beam steering antenna arrays for mobile and wireless applications using the genetic algorithm (GA) and particle swarm optimisation (PSO) techniques as optimisation design tools. Several antenna designs were implemented and tested: initially, a printed dipole antenna integrated with a duplex RF switch used for mobile base station antenna beam steering was investigated. A coplanar waveguide (CPW) to coplanar strip (CPS) transition was adopted to feed the printed dipole. A novel RF switch circuit, used to control the RF signal fed to the dipole antenna and placed directly before it, was proposed. The measured performance of the RF switch was tested and the results confirmed its viability. Then two hybrid coupled PIN diode phase shifters, using Branchline and Rat-Race ring coupler structures, were designed and tested. The generation of four distinct phase shifts was implemented and studied. The variations of the scattering parameters were found to be realistic, with an acceptable ±2 phase shift tolerance. Next, antenna beam steering was achieved by implementing RF switches with ON or OFF mode functions to excite the radiating elements of the antenna array. The switching control process was implemented using a genetic algorithm (GA) method, subject to scalar and binary genes. Anti-phase feeding of radiating elements was also investigated. A ring antenna array with reflectors was modelled and analysed. An antenna of this type for mobile base stations was designed and simulation results are presented. Following this, a novel concept for simple beam steering using a uniform antenna array operated at 2.4 GHz was designed using GA. The antenna is fed by a single RF input source and the steering elements are reactively tuned by varactor diodes in series with small inductors. The beam-control procedure was derived through the use of a genetic algorithm based on adjusting the required reactance values to obtain the optimum solution as indicated by the cost function. The GA was also initially used as an optimisation tool to derive the antenna design from its specification. Finally, reactive loading and time modulated switching techniques are applied to steer the beam of a circular uniformly spaced antenna array having a source element at its centre. Genetic algorithm (GA) and particle swarm optimisation (PSO) processes calculate the optimal values of reactances loading the parasitic elements, for which the gain can be optimised in a desired direction. For time modulated switching, GA and PSO also determine the optimal on and off times of the parasitic elements for which the difference in currents induced optimises the gain and steering of the beam in a desired direction. These methods were demonstrated by investigating a vertically polarised antenna configuration. A prototype antenna was constructed and experimental results compared with the simulations. Results showed that near optimal solutions for gain optimisation, sidelobe level reduction and beam steering are achievable by utilising these methods. In addition, a simple switching process is employed to steer the beam of a horizontally polarised circular antenna array. A time modulated switching process is applied through Genetic Algorithm optimisation. Several model examples illustrate the radiation beams and the switching time process of each element in the array.

This work focuses on efficient modelling and adaptive control of friction damping in bladed disks. To efficiently simulate the friction contact, a full-3D time-discrete contact model is reformulated and an analytical expression for the Jacobian matrix is derived that reduces the computation time drastically with respect to the classical finite difference method. The developed numerical solver is applied on bladed disks with shroud contact and the advantage of full-3D contact model compared to a quasi-3D contact model is presented. The developed numerical solver is also applied on bladed disks with strip damper and multiple friction contacts and obtained results are discussed. Furthermore, presence of higher harmonics in the nonlinear contact forces is analyzed and their effect on the excitation of the different nodal diameters of the bladed disk are systematically presented. The main parameters that influence the effectiveness of friction damping in bladed disks are engine excitation order,  contact stiffnesses,  friction coefficient, relative motion at the friction interface and the normal contact load. Due to variation in these parameters during operation, the obtained friction damping in practice may differ from the optimum value. Therefore, to control the normal load adaptively that will lead to an optimum damping in the system despite these variations, use of magnetostrictive actuator is proposed. The magnetostrictive material that develops an internal strain under the influence of an external magnetic field is employed to increase and decrease the normal contact load. A linearized model of the magnetostrictive actuator is used to characterize the magnetoelastic behavior of the actuator.  A nonlinear static contact analysis of the bladed disk reveals that a change of normal load more than 700 N can be achieved using a reasonable size of the actuator. This will give a very good control on friction damping once applied in practice. / <p>QC 20170310</p> / TurboPower

This project addresses the contemporary and competing non-state governmentalities in the Gaza Strip through an analysis of the 1948-1967 period. During this period the American Friends Service Committee (AFSC), the United Nations Relief and Works Agency (UNRWA), and the Young Men's Christian Association (YMCA) constructed early notions of non-state 'governance' and quasi-citizenship in Gaza. The majority of this research focuses on these organizations in the 1948-1967 period, however, there is a case study that addresses the way in which these competing models of non-sovereign administration impacted the approaches used since 2007 by Hamas. The distinct histories and experiences of administration under each organization has created competing notions of what components constitute an assembled notion of citizenship in Gaza. Specifically, the bureaucratic categorization preferred by UNRWA conflicts with Hamas' focus on individualized service based on the tradition of shura (consultation) and youth training, in particular. Several approaches to governance in Gaza are common to the three major faith-based organizations discussed here (the AFSC, the YMCA, and the Hamas). Notably, these organizations create sacred spaces and processes as a mechanism of governance, allowing them to exert control over the population. In particular, the manner in which two distinct international organizations – UNRWA and Hamas – came to operate parallel state structures in the Gaza Strip, and the way that these two organizations imbue citizenship like rights and responsibilities on the populations that they serve is of particular interest. In this way governance in the Gaza Strip has completed a circuit: from the faith-based Friends to the faith-based Hamas, with UNRWA as the constant secular parallel authority. Through an examination of organizational archives, memoirs, and interviews this project links these events, arguing that the institutional records of these organizations provide an illuminating path to better understand the situation of governance in Gaza today.

Nesta dissertação de mestrado foram utilizadas duas ligas de alumínio (AA1100 e AA5052) para a produção de uma microestrutura final apresentando tamanho médio de grãos menores que um micrometro. Tal fato foi possível através do processo de Accumulated Roll Bonding (ARB). Tais materiais produzidos por ARB, foram caracterizados conforme propriedades mecânicas (microdureza, limite de escoamento e resistência) e microestruturais (tamanho de grão e macrotextura e composição química dos precipitados). O principal resultado para este trabalho foi a produção de tiras de AA 1100 e AA 5052 com tamanho médio de grão de 0,50 ± 0,04 m e 0,42 ± 0,06 m respectivamente. Tal resultado é coerente em comparação à literatura. Com relação aos resultados de textura, tais amostras apresentaram temperatura de recristalização acima de 473K e componente de textura típicas de cisalhamento (tanto para o material oriundo de fábrica como para o material laminado). Tal fato é esperado já que não se utilizou lubrificação durante ensaios de laminação. A propriedade mecânica de microdureza de AA 1100 ficou coerente com a literatura embora as propriedades de limite de escoamento e de resistência possuíram módulos abaixo da literatura. / The present work is related to the production, in a laboratory scale, of a metallic microstructure having a grain size smaller than one micrometer, through the Accumulated Roll Bonding technique(ARB), for two different aluminum alloys, namely AA 1100 and AA 5052. The strips obtained by the ARB technique have been characterized by their mechanical properties (microhardness, yield and tensile strength), and their microstructure (grain size, macrotexture and precipitates chemical composition). The main result of this work has been the rolling of AA1100 and AA5052 strips with an average grain size of 0.5 ± 0.04 m and 0.42 ± 0.06 m respectively. Such results are consistent with the literature. Relative to the texture, the samples presented a recrystallization temperature higher than 473K and typical shear texture components (due to the dry rolling conditions during the ARB). Microhardness of the AA110 was consistent with literature data; however yield and tensile strength presented values that were lower than those observed in the literature.

Dans cette thèse, on s'est attaché à résoudre un certain nombre de problèmes qui apparaissent lorsqu'on traite des problèmes concrets de contrôle: phénomènes à plusieurs échelles de temps, discontinuités de la commande lors du basculement d'un correcteur à un autre, nécessité de concevoir un nombre limité de correcteurs différents malgré une gamme très importante des produits traités. Pour illustrer concrètement les résultats obtenus, nous nous sommes appuyés sur un exemple industriel concret, le contrôle de guidage de bande durant le processus de laminage dans un laminoir à chaud. D'abord, nous proposons une solution convexe au problème de commande optimale linéaire quadratique pour les systèmes linéaires à deux échelles de temps en temps discret. Ensuite, nous établissons des conditions suffisantes, formulées sous la forme d'inégalités matricielles linéaires, qui permettent de vérifier la stabilité d'un système à commutation à deux échelles de temps et de synthétiser des correcteurs stabilisants. Nous proposons aussi dans ce travail une méthode pour minimiser les discontinuités sur la commande dans le cadre des systèmes à commutation. Dans le contexte du contrôle de guidage de bande pour un laminoir à chaud, nous ne pouvons pas négliger l'influence des paramètres incertains, qui sont dus principalement au fait que ce genre de système traite une gamme de produits très large. Donc, dans la synthèse du correcteur, nous prenons en compte ces variations en divisant l'ensemble des produits en plusieurs familles et en synthétisant un correcteur différent pour chaque famille / This Ph.D. thesis deals with a certain number of problems arising in practical implementation of control systems: multi time scale phenomena, sudden modifications on the system dynamics, discontinuities on the control signal due to controller switchings, the need of design a limited number of controllers in spite of a wide variation on the physical parameters. In order to illustrate the validity of the obtained results, we resort to a real problem concerning the steel production framework, the robust steering control of a hot strip finishing mill. First, a convex solution of the linear quadratic control design for discrete two time scale systems is proposed. Hence, we address the stability problem of two time scale switched systems. We show that stability of the slow and fast switched subsystems under arbitrary switching rules does not imply the stability of the corresponding two time scale switched system in the singular perturbation form. An additional constraint, independent of the value of the singular parameter and of the switching rule, is provided in terms of linear matrix inequalities. We also introduce a bumpless transfer method for switched systems aiming at reducing the discontinuities on the control signal. Dwell time conditions assessing the asymptotic stability of the closed loop switched system are established. The practical contribution of this thesis, the robust steering control design, exploits most of previous results. The objective is to guarantee the stability of the hot strip mill system and improve the quality of the rolled products

Apresenta-se neste trabalho um estudo teórico-experimental sobre a instabilidade de perfis formados a frio submetidos à flexão. A instabilidade distorcional se faz comum na presença de tensões de compressão atuando sobre perfis enrijecidos e fabricados com aços de elevada resistência mecânica. A parte teórica abrange os métodos de cálculo analíticos e numéricos para a análise de instabilidade distorcional de perfis de seção aberta formados a frio. Na parte experimental inclui-se o estudo de perfis formados a frio com seções do tipo U enrijecidos submetidos aos ensaios à flexão. Nestes ensaios variou-se a altura de alma e espessura de chapa procurando-se abranger maior número de condições geométricas para análise da estabilidade distorcional. Inclui-se também a análise de instabilidade numérica dos perfis do programa experimental através do método de resistência direta via método das faixas finitas. Com base nos resultados experimentais, numéricos e na análise teórica do problema, verificou-se o procedimento adotado pela NBR14762/2001 e efetuou-se comparação entre curvas de resistência propostas para o dimensionamento de perfis formados a frio à flexão. Foi verificado que o fenômeno de instabilidade distorcional pode ser o estado limite último crítico para o dimensionamento dos perfis formados a frio. / This work present a study theoretical-experimental about the distortional buckling of cold-formed steel members under bending. The distortional buckling is common for members with edge-stiffened sections and manufactured with steel of high strength. The theorical part present the analitic and numerical methods for stability analysis by distortional buckling. The experimental part included the study of cold-formed with sections channel altering flange width and thickness by proof in flexural members. Included too the numerical analysis by Direct Strength Method in Finite Strip Method on members with the same configurations of experimental investigation. Based on the experimental measurements, numerical analysis and in the theorical analysis of work, verified the procedures adopted in brazilian code NBR14762/2001 and compared with others distortional curve proposed for to design of cold-formed members under bending. Verified that the distortional buckling may control the design being the critical mode for the ultimate limit state.

Neste trabalho estudamos aspectos algorítmicos do Problema da Cobertura por Sensores. Em linhas gerais, este problema a entrada consiste em uma região a ser monitorada por um conjunto de sensores previamente posicionados, cada qual dotado de bateria com duração limitada, e o objetivo é atribuir a cada sensor um tempo de início, de modo que toda a região seja coberta o maior tempo possível. Focamos nosso estudo no caso unidimensional do problema, chamado Problema da Cobertura de Faixa Restrita, no qual a região a ser monitorada é um intervalo (da reta real). Estudamos diversas variantes, de acordo com os subintervalos que os sensores cobrem (se de tamanhos fixos ou variados), e de acordo com a duração das baterias (se uniformes ou não). Estudamos também o caso preemptivo: quando os sensores podem ser ligados mais de uma vez. Para este último caso, projetamos um algoritmo polinomial bem simples. O Problema da Cobertura de Faixa Restrita é NP-difícil no caso não-preemptivo em que os sensores têm bateria de duração variável. Para este caso, em 2009 Gibson e Varadarajan apresentaram um algoritmo polinomial que provaram ser uma 5-aproximação. Provamos que este algoritmo tem fator de aproximação 4, e mostramos que este fator é justo. Apresentamos também formulações lineares inteiras para este caso, e os resultados computacionais obtidos. / We study the algorithmic aspects of the Sensor Cover Problem. Broadly speaking, in this problem the input consists of a region to be covered by a set of sensors previously positioned, each one powered with a battery of limited duration, and the objective is to assign to each sensor an initial time, so as to cover the given region for as long as possible. We focus our study on the one-dimensional case of the problem, called Restricted Strip Cover Problem, in which the region to be covered is an interval (of the real line). We study several variants, according to the type of the subintervals the sensors cover (if they have fixed length or not), to the duration of the batteries (if uniform or not). We also study the preemptive case: when the sensors can be turned on and off more than once. For this case, we designed a simple polynomial-time algorithm. The Restricted Strip Cover Problem is NP-hard in the non-preemptive case in which the sensors have non-uniform duration batteries. For this case, in 2009 Gibson and Varadarajan designed a polynomial-time algorithm which they proved to be a 5-aproximation. We prove that this algorithm has approximation ratio 4, and show that this ratio is tight. We also present two integer linear formulations for this case, and report on the computational results obtained with this approach.

Skin, more specifically the outermost skin layer, the stratum corneum (SC), forms an extremely effective barrier, preventing both the loss of heat and water, and the ingress of micro-organisms and chemicals. Assessing the rate and extent of drug permeation into or through the skin is important both to evaluate the usefulness of a drug for topical or transdermal delivery, and to compare different formulations to assess their bioequivalence. Prediction of drug permeation is logistically, ethically and economically preferable to in vivo measurements. The recent progress that has been made with empirical and mechanistic mathematical models, along with in vitro diffusion cell techniques has been reviewed. However, currently, in vivo measurements, in man, are still required. For new chemical entities, the need for clinical trials is clear. In the case of generic products, however, there is considerable effort currently being expended to replace expensive, subjective clinical trials with objective, validated measurements of drug permeation, in vivo, in particular to assess bioequivalence. The tape stripping technique has emerged as a promising technique to objectively measure drug permeation through skin, and is the focus of this thesis. After formulation application and removal, layers of SC are sequentially removed by adhesive tapes. As the SC performs the main barrier function of the skin, measuring the rate and extent of drug permeation through this layer is assumed to be related to overall topical bioavailability. The work in this thesis concentrates on performing tape stripping studies such that all tapes are analysed individually, and drug concentration as a function of SC depth is measured. The concentration depth profiles across the SC may be fitted to an appropriate solution of Fick's second law of diffusion to obtain estimates of the vehicle-SC partition coefficient and the drug's diffusivity in the membrane. These dermato-pharmacokinetic parameters may be compared for different formulations.

Made available in DSpace on 2016-04-25T20:21:02Z (GMT). No. of bitstreams: 1 Cristina Maranhao.pdf: 11708246 bytes, checksum: a0bee347f82f275fe29d92e5d9847d6b (MD5) Previous issue date: 2013-10-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This thesis seeks to comprehend the imagetic construction of contemporary wars transmitted by national and international media, through the case study of two current conflicts: the war between police and drug dealers at Rio de Janeiro´s favelas of Complexo do Alemão, and the armed conflict between israelis and palestinians in the Gaza Strip, involving the Palestine Question. Devided in two parts, war and image, this work shows how significative changes occurred in the form of the warfare, associated to new global economic formula, originated from globalization and mundialization. These changes reflected in the form of representing the armed conflicts and therefore in the current photojournalism. . From the observation of significative diferences in the field of images, we focus in two aspects: the image as an action of imagination, and the image as excessive production of clichés from the society of the spectacle . This thesis proposes the construction of a western imagery catalog, elaborated from the relationship between the analysed images of conflicts and the images collected from paints, engraving or photographs. This proposition occured because we realised that there is an imagetic construction of war, wich is responsable for the imaginary of the warrior and of conflicts. Images of war today have changed along with changes of the armed conflict universe, demonstrating a reverberation of images and specific subjects turned into simple pictural clichés, wich in many cases do not represent the violence experienced by the population envolved. This reverberation expresses the generalization of images of war today / Esta tese procura compreender a construção imagética das guerras contemporâneas veiculadas pela mídia nacional e internacional por meio do estudo de caso de dois conflitos atuais: a guerra travada entre policiais e traficantes nas favelas cariocas do Complexo do Alemão e o conflito armado entre israelenses e palestinos na Faixa de Gaza que envolve a Questão Palestina. Dividido em duas partes, guerra e imagem, o trabalho mostra como ocorreram mudanças significativas na forma de guerrear associadas a nova formulação econômica global proveniente da globalização e da mundialização. Estas mudanças refletiram-se na forma de representar os conflitos armados e consequentemente no fotojornalismo atual. A partir da constatação de diferenças significativas no campo da imagem, nos concentramos dois aspectos: a imagem como uma ação do imaginar e a imagem como produção excessiva e formadora de clichês provenientes da sociedade do espetáculo . A tese propõe a construção de um catálogo imagético ocidental elaborado a partir da relação entre as imagens analisadas dos conflitos e imagens coletadas seja na pintura, em gravuras ou na fotografia. A proposta deste ocorreu, pois percebemos que existe uma construção imagética da guerra esta que é responsável pela elaboração do imaginário do guerreiro e dos conflitos. As imagens de guerra na atualidade se modificaram juntamente com as alterações do universo dos conflitos armados, demonstrando uma reverberação de imagens e de temas específicos transformando em meros clichês imagéticos que em muitos casos não representa a violência vivenciada pela população que está envolvida. Reverberação, esta, que expressa a generalização das imagens de guerra na atualidade