Vibro-impact systems are extensively used in engineering and physics field, such as impact damper, particle accelerator, etc. These systems are most basic elements of many real world applications such as cars and aircrafts. Such vibro-impact systems possess both the continuous characteristics as continuous dynamical systems and discrete characteristics introduced by impacts at the same time. Thus, an appropriately developed discrete mapping system is required for such vibro-impact systems in order to simplify investigation on the complexity of motions. In this dissertation, a few vibro-impact oscillators will be investigated using discrete maps in order to understand the dynamics of vibro-impact systems. Before discussing the nonlinear dynamical phenomena and behaviors of these vibro-impact oscillators, the theory for nonlinear discrete systems will be applied to investigate a two-dimensional discrete system (Henon Map). And the complete dynamics of such a nonlinear discrete dynamical system will be presented using the inversed mapping method. Neimark bifurcations in such a discrete system have also drawn a lot of interest to the author. The Neimark bifurcations in such a system have actually formed a boundary dividing the stable solution of positive and negative maps (inversed mapping). For the first time, one is able to obtain a complete prediction of both stable and unstable solutions in such a discrete dynamical system. And a detailed parameter map will be presented to illustrate how changes of parameters could affect the different solutions in such a system. Then, the theory of discontinuous dynamical systems will be adopted to investigate the vibro-impact dynamics in several vibro-impact systems. First, the bouncing ball dynamics will be analytically discussed using a single discrete map. Different types of motions (periodic and chaotic) will be presented to understand the complex behavior of this simple model. Analytical condition will be expressed using switching phase of the system in order to easily predict stick and grazing motion. After that, a horizontal impact damper model will be studied to show how complex periodic motions could be developed analytically. Complete set of symmetric and asymmetric periodic motions can also be easily predicted using the analytical method. Finally, a Fermi-Accelerator being excited at both ends will be discussed in detail for application. Different types of motions will be thoroughly studied for such a vibro-impact system under both same and different excitations.

This dissertation presents a methodology to simulate the dispersion of water droplets in the air flow typical of an Icing Tunnel. It is based on the understanding the physical parameters that influence the uniformity and the distribution of cloud of droplets in the airflow and to connect them with analytical parameters which may be used to describe the dispersion process. Specifically it investigates the main geometrical and physical parameters contributing to the droplets dispersion at different tunnel operative conditions, finding a consistent numerical approach to reproduce the local droplets dynamic, quantifying the possible limits of commercial CFD methods, pulling out the empirical parameters/constant needing to simulate properly the local conditions and validating the results with calibrated experiment. An overview of the turbulence and multiphase flow theories, considered relevant to the Icing Tunnel environment, is presented as well as basic concepts and terminology of particle dispersion. Taylor’s theory of particle dispersion has been taken as starting point to explain further historical development of discrete phase dispersion. Common methods incorporated in commercial CFD software are explained and relative shortcomings underlined. The local aerodynamic condition within tunnel, which are required to perform the calculation with the Lagrangian particle equation of motions, are generated numerically using different turbulent models and are compared to the historical K-ε model. Verification of the calculation is performed with grid independency studies. Stochastic Separated Flow methods are applied to compute the particle trajectories. The Discrete Random Walk, as described in the literature, has been used to perform particle dispersion analysis. Numerical settings in the code are related to the characteristics of the local turbulent condition such as turbulence intensity and length scales. Cont/d.

abstract: This thesis explores the impact of different experimental design strategies for the development of quantile regression based metamodels of computer simulations. In this research, the objective is to compare the resulting predictive accuracy of five experimental design strategies, each of which is used to develop metamodels of a computer simulation of a semiconductor manufacturing facility. The five examined experimental design strategies include two traditional experimental design strategies, sphere packing and I-optimal, along with three hybrid design strategies, which were developed for this research and combine desirable properties from each of the more traditional approaches. The three hybrid design strategies are: arbitrary, centroid clustering, and clustering hybrid. Each of these strategies is analyzed and compared based on common experimental design space, which includes the investigation of four densities of design point placements three different experimental regions to predict four different percentiles from the cycle time distribution of a semiconductor manufacturing facility. Results confirm that the predictive accuracy of quantile regression metamodels depends on both the location and density of the design points placed in the experimental region. They also show that the sphere packing design strategy has the best overall performance in terms of predictive accuracy. However, the centroid clustering hybrid design strategy, developed for this research, has the best predictive accuracy for cases in which only a small number of simulation resources are available from which to develop a quantile regression metamodel. / Dissertation/Thesis / Masters Thesis Engineering 2016

Made available in DSpace on 2014-06-11T19:22:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-07-10Bitstream added on 2014-06-13T18:49:40Z : No. of bitstreams: 1 caun_ap_me_ilha.pdf: 919724 bytes, checksum: afeca633ca3cfd0780cb33c363186934 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho apresenta uma nova estratégia de controle discreto. A técnica é baseada em Modos Deslizantes Discretos, utilizando uma lei de controle suave. Quando um algoritmo de controle é implementado em um computador digital, existe um atraso no tempo de computação, devido ao tempo de execução das instruções. Neste trabalho, vamos assumir que estes atrasos são constantes e menores que um período de amostragem. A presença do atraso no tempo de computação não apenas reduz a estabilidade e robustez, mas também degrada a performance de controle. O novo controlador proposto é projetado para atuar na presença destes atrasos, melhorando substancialmente o desempenho do controle. Outra propriedade importante deste controlador é a possibilidade de trabalhar com períodos de amostragem mais altos, garantindo o uso de freqüências mais baixas de processamento, ou seja, proporcionando uma economia do hardware de atuação. A nova lei de controle proposta foi aplicada na estabilização de quatro sistemas incertos e de natureza instável: Sistema Bola e Viga, Sistema Pêndulo Invertido Linear, Sistema Pêndulo Invertido Rotacional e Sistema Pêndulo Invertido Rotacional Duplo. Resultados das simulações são apresentados e comparados com resultados de outro controlador de Modo Deslizante, proposto na literatura, caracterizando um estudo comparativo, onde a eficácia do novo controlador projetado se mostra evidente, devido a seu algoritmo de fácil elaboração prática. Para melhor visualização do comportamento dos sistemas estudados e visando a contribuição no aprendizado de sistemas de controle, modelos de animação em três dimensões foram utilizados. / This work presents a new strategy of discrete-time control. The technique is based on Discrete-Time Sliding Modes, using a smooth control law. When a control algorithm is implemented in a digital computer, there is a computation time delay, due the execution time of the instructions. In this work, we go to assume that these delays are constant and smaller than a sampling period. The presence of the computation time delay not only reduces the stability and robustness, but also degrades the control performance. The new considered controller is projected to work in the presence of these delays, improving substantially the performance of the control. Another important property of this controller is the possibility to work with higher sampling periods, guaranteeing the use of lower frequencies of processing, providing an economy of the actuation hardware. The new control law proposal was applied in the stabilization of four uncertain systems with unstable nature: Ball and Beam System, Linear Inverted Pendulum System, Rotational Inverted Pendulum System and Double Rotational Inverted Pendulum System. Simulations results are presented and compared with results of other Sliding Mode controller, proposed in the literature, characterizing a comparative study, where the effectiveness of the new designed controller shows evident, due your algorithm of easy practical elaboration. For better visualization of the behavior of the systems studied and aiming at the contribution in the learning of control systems, models of animation in three dimensions had been used.

Submitted by MATHEUS PALMERO SILVA null (matheuspalmero@gmail.com) on 2017-10-23T17:38:42Z No. of bitstreams: 1 Palmero-Dissertação-Final+Ficha.pdf: 7872041 bytes, checksum: 4aced1a4e65b4822d5cad50fbfb47973 (MD5) / Rejected by Luiz Galeffi (luizgaleffi@gmail.com), reason: Solicitamos que realize uma nova submissão seguindo as orientações abaixo: Inserir o número do processo de financiamento FAPESP nos agradecimentos da tese/dissertação. Corrija estas informações e realize uma nova submissão contendo o arquivo correto. Agradecemos a compreensão. on 2017-10-26T16:22:04Z (GMT) / Submitted by MATHEUS PALMERO SILVA null (matheuspalmero@gmail.com) on 2017-10-26T16:38:06Z No. of bitstreams: 1 Palmero-Dissertação-Final+Ficha.pdf: 7872232 bytes, checksum: 5757e6926325d1f74438fff3cd26d5e0 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-10-26T16:55:48Z (GMT) No. of bitstreams: 1 silva_mp_me_rcla.pdf: 7872232 bytes, checksum: 5757e6926325d1f74438fff3cd26d5e0 (MD5) / Made available in DSpace on 2017-10-26T16:55:48Z (GMT). No. of bitstreams: 1 silva_mp_me_rcla.pdf: 7872232 bytes, checksum: 5757e6926325d1f74438fff3cd26d5e0 (MD5) Previous issue date: 2017-09-01 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Nesta dissertação, investigamos propriedades estatísticas de alguns sistemas dinâmicos descritos por mapeamentos discretos nas proximidades de duas transições: (i) integrabilidade para não integrabilidade e; (ii) crescimento limitado de energia para crescimento ilimitado de energia (aceleração de Fermi). O foco principal está na descrição do comportamento da distribuição de probabilidade da velocidade/energia das partículas em dinâmica caótica. A quebra de simetria da distribuição de probabilidade leva a uma escala adicional àquelas já conhecidas na literatura e, com este estudo, acreditamos que a quebra de simetria também possa explicar um fenômeno que já vem sendo observado em mapeamentos discretos. Fenômeno este, até então descrito apenas fenomenologicamente, teve sua primeira observação na publicação seminal de investigação de leis de escala em mapeamentos discretos no periódico Phys. Rev. Let. 93, 014101 (2004), de Edson D. Leonel, Peter V. E. McClintock e Jafferson K. L. Silva. Nossa contribuição para o problema está no desenvolvimento de descrições analíticas e verificações numéricas, baseadas em um estudo sistemático do comportamento difusivo das trajetórias caóticas no espaço de fases dos sistemas dinâmicos de interesse. / In this dissertation, we investigate statistical properties of some dynamical systems described by discrete mappings near two types of transitions: (i) integrability to non-integrability; (ii) limited to unlimited diffusion in energy (Fermi acceleration). The main goal is to describe the behaviour of the probability density of the velocity/energy for a set of particles moving in a chaotic dynamics. The break of symmetry in the probability distribution leads to an additional scaling to those are already known in the literature and, with this study, we believe that the symmetry break might also explain a well-known phenomenon observed for discrete mappings. This phenomenon, it has been reported so far phenomenologically. A first observation in an area-preserving mapping was in a letter published in Phys. Rev. Let. 93, 014101 (2004), authored by Edson D. Leonel, Peter V. E. McClintock and Jafferson K. L. Silva. Our contribution to the problem is on the development of an analytical approach and numerical verifications, based essentially on a systematic study of the diffusive behaviour of chaotic trajectories on the phase space of dynamical systems of interest. / FAPESP: 2014/27260-5

Neste trabalho foi estudado o espectro das ondas de MHD ideal em um plasma cilíndrico. Considerando o plasma inomogêneo, o espectro apresenta regiões discretas e contínuas: onda lenta e onda de Alfvén. Os automodos das regiões discretas são as soluções da equação de Hain-Lüst e, nas regiões contínuas, as autofunções apresentam singularidades. Foram determinadas expressões analíticas em termos da função de Bessel que os autovalores da onda de Alfvén apresentam o comportamento discreto. Os modos globais discretos de Alfvén foram calculados usando um equilíbrio da configuração de tokamak, beta < 1, e estes modos apresentam uma pequena contribuição da onda compressional. Foi feita uma análise da propagação da energia da onda por meio do vetor de Poynting e este conhecimento tem a sua importância no problema de aquecimento do plasma por ondas de Alfvén. Foi feita, também, uma análise da polarização das ondas. Foi estudado o espectro da onda devido ao efeito de beta, beta > 1. Esta condição é mais aplicável em problemas de plasma espacial, por exemplo, na fotosfera solar. Foram obtidos, pela primeira vez, os modos discretos de onda lenta, previstos teoricamente. As suas soluções (autofunções e autovalores) possuem também a característica global, aqui denominadas de modos globais discretos da onda lenta. Outro estudo do problema espectral foi realizado para urna configuração de equilíbrio para RFP (\"Reversed Field Pinch\"). Determinou-se, além dos automodos Sturmianos da onda de Alfvén, os automodos anti-Sturmianos da onda lenta. / The spectrum of the ideal MHD waves in cylindrical plasmas has been studied. Assuming non homogeneous plasma, the spectrum presents the discrete and continuum (slow and Alfvén waves) regions. The eigenfunctions of the discrete regions are the solutions of the Hain-Lüst equation. In the continua, the solutions of this equation have singularities. It has been determined analytical expressions for the discrete eigenfunctions. These happen to be the Bessel\'s function and its eigenvalues agree with the numerical calculations. The discrete modes (global modes) of Alfvén waves have been calculated by numerically using the equilibrium configuration of tokamaks, beta < 1, and it was observed that these modes present a small contribution from the compressional waves. An analysis of the energy propagation was done using the Poynting vector. This has its importance in the problem of plasma heating by Alfvén waves. Its polarization was also studied. The effect of beta, through values greater than 1, was also studied. This condition is more aplicable to the spacial plasma problems, for example, in the solar photosphere\'s plasma. It has been calculated, for the first time, the discrete modes of slow waves, proposed theoretically. Its solutions (eigenfunctions and eigenvalues) have also the characteristics of the global modes, called global discrete slow waves. The study of spectral problems for the Reversed Field Pinch configurations was also determined here for both Sturmian eigenmodes for the Alfvén waves and Anti-Sturmian eigenmodes for the slow waves.

São apresentados resultados envolvendo subespaços discretos em diversos tipos de problemas em Topologia Geral. São também apresentadas construções de contraexemplos tanto em ZFC como com axiomas extras. / It is presented some results involving discrete subspaces in many kind of problems in General Topology. It is also presented some constructions of counterexamples in ZFC and assuming extra axioms.

Les composants optiques de silice traversés par des flux lasers de haut niveau d'énergie à des longueurs d'onde de 351 nm peuvent être soumis à des endommagements. Il est admis que la présence de microfissures en sous surface, induit par les procédés d'abrasion des composants optiques, joue un rôle clé dans l'initiation des dommages lasers. Cette thèse propose de simuler le procédé de surfaçage par la méthode des éléments discrets afin de caractériser la densité et la répartition des microfissures en fonction des paramètres d'usinage. / When fused silica optics are submitted to high-power laser (such as megajoule laser or National Ignition Facility) at the wavelength of 351 nm, fused silica optics can exhibit damage, induced by the high amount of energy traversing the part. Current researches have shown that this damage could be initiated on pre-existing sub-surface damages created during the polishing processes. The discrete element method (DEM) is proposed to simulate the polishing process and its impact on sub-surface damage creation.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14624号 / 工博第3092号 / 新制||工||1460(附属図書館) / 26976 / UT51-2009-D336 / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 引原 隆士, 教授 北野 正雄, 准教授 山田 啓文 / 学位規則第4条第1項該当

Discrete choice experiments (DCEs) are a stated preference valuation method. As a ubiquitous component of healthcare delivery, risk is increasingly used as an attribute in DCEs. Risk is a complex concept that is open to misinterpretation; potentially undermining the robustness of DCEs as a valuation method. This thesis employed quantitative, qualitative and eye-tracking methods to understand if and how risk communication formats affected individuals’ choices when completing a DCE and the valuations derived. This thesis used a case study focussing on the elicitation of women’s preferences for a national breast screening programme. Breast screening was chosen because of its relevance to primary care and potential contribution to the ongoing debate about the benefits and harms of mammograms. A DCE containing three attributes (probability of detecting a cancer; risk of unnecessary follow-up; and cost of screening) was designed. Women were randomised to one of two risk communication formats: i) percentages only; or ii) icon arrays and percentages (identified from a structured review of risk communication literature in health).Traditional quantitative analysis of the discrete choices made by 1,000 women recruited via an internet panel revealed the risk communication format made no difference in terms of either preferences or the consistency of choices. However, latent class analysis indicated that women’s preferences for breast screening were highly heterogeneous; with some women acquiring large non-health benefits from screening, regardless of the risks, and others expressing complete intolerance for unnecessary follow-ups, regardless of the benefits. The think-aloud method, identified as a potential method from a systematic review of qualitative research alongside DCEs, was used to reveal more about DCE respondents’ decision-making. Nineteen face-to-face cognitive interviews identified that respondents felt more engaged with the task when risk was presented with an additional icon array. Eye-tracking methods were used to understand respondents’ choice making behaviour and attention to attributes. The method was successfully used alongside a DCE and provided valid data. The results of the eye-tracking study found attributes were visually attended to by respondents most of the time. For researchers seeking to use DCEs for eliciting individuals’ preferences for benefit-risk trade-offs, respondents were more receptive to risk communicated via an icon array suggesting this format is preferable. Policy-makers should acknowledge preference heterogeneity, and its drivers, in their appraisal of the benefits of breast screening programmes. Future research is required to test alternative risk communication formats and explore the robustness of eye-tracking and qualitative research methods alongside DCEs.