O desempenho global dos sistemas computacionais é limitado, geralmente, pelo componente de menor desempenho. Os processadores e a memória principal têm experimentado um aumento de desempenho bem maior que o da memória secundária, como os discos magnéticos. Em 1984, Johnson introduziu o conceito de fragmentação, onde um dado é gravado em uma matriz de discos, de forma que os seus fragmentos podem ser recuperados em paralelo e, por conseqüência, de forma mais rápida. O principal problema da fragmentação é a redução da confiabilidade da matriz pois, a falha de um dos discos torna o dado inacessível. Patterson, Gibson e Katz propuseram, em 1988, 5 formas de armazenar informação redundante na matriz de discos e, dessa forma, aumentar sua confiabilidade. A essas formas foi dado o nome de RAID - Redundant Arrays of Independent Disks. Com o passar do tempo, outras formas de armazenamento de redundância foram criadas, tornando complexa a taxonomia da área. Além disso, alterações de parâmetros na matriz implicam em variações de desempenho nem sempre fáceis de se perceber em um primeiro momento. Com o objetivo de facilitar a compreensão da taxonomia e permitir que sejam feitos experimentos na matriz buscando um melhor desempenho, esta dissertação propõe um ambiente de simulação e aprendizado para RAID, onde o usuário pode interagir com diversos modelos de RAID, ou até criar o seu próprio, para avaliar seu desempenho em várias situações, além de oferecer ao usuário acesso ao conhecimento da área, agindo como um tutor. Esta dissertação apresenta, ainda, um protótipo de um simulador de discos magnéticos que pode ser utilizado como base para o desenvolvimento de um simulador de RAID para ser utilizado pelo ambiente. / The component with the worst performance usually limits the overall performance of a computing system. The performance of processors and main memory has improved faster than the secondary memory, such as magnetic disks. Johnson, in 1984, introduced the concept of fragmentation, in which a data file is written into a disk array, in a way that its stripes can be recovered in parallel and therefore, in a faster way. The main problem with fragmentation is the reduction of the reliability. If one disk fails, all data file becomes inaccessible. Patterson, Gibson and Katz proposed, in 1988, five ways to store redundant information in the array, increasing the reliability, comprising the main RAID (Redundant Array of Independent Disks) configurations. Some other ways to store the redundant information have been proposed over the years, making the RAID taxonomy more complex. Furthermore, changes in the array parameters takes to performance variations that are not always understood. With the purpose of facilitating the comprehension of the taxonomy and allowing the execution of experiments looking forward to improve performance, this MSc Dissertation proposes an Intelligent Simulation and Learning Environment for RAID, where the user can interact with several RAID models, or even create his/her own models, in order to evaluate their performance under different situations. The environment also allows the user to interact with the knowledge of the area, acting as a tutor. This Dissertation also presents a prototype of a magnetic disk simulator, that can be used as the kernel for the development of a RAID simulator to be used by the environment.

Neste trabalho foi desenvolvido um novo m´etodo de s´ntese espectral para modelar o disco de acres¸cao de vari´aveis catacl´smicas (VCs) nao magn´eticas. O principal objetivo deste trabalho ´e analisar a emissao do cont´nuo e das linhas em uma ampla faixa espectral no ultravioleta (UV). O disco ´e separado em an´eis concentricos e, para cada anel uma atmosfera de disco com vento ´e calculada. Na base, as atmosferas sao calculadas consistemente com o vento, tendo a distribui¸cao de densidade dos modelos de atmosferas de disco de Wade e Hubeny. A estrutura ´e calculada no sistema co-m´ovel com um perfil de velocidade vertical obtido da solu¸cao da equa¸cao de Euler para um disco de acres¸cao. O comportamento das linhas e do cont´nuo como fun¸cao da inclina¸cao orbital ´e consistente com as observa¸coes. Tamb´em foi verificado que a taxa de acres¸cao influi sobre a temperatura do vento levando `as mudan¸cas correspondentes nas intensidades relativas das linhas. Foi encontrado que a massa da prim´aria tem uma forte influencia na profundidade dos perfis de absor¸cao. Tamb´em, encontramos que a os perfis de linha sao fortemente sens´veis ao incremento da taxa de perda de massa, aumentado a intensidade das linhas de emissao. Foram escolhidos dados espectrosc´opicos no UV de duas VCs Nova-like (NL) de baixa inclina¸cao, RW Sex e V3885 Sgr e dois sistemas de alta inclina¸cao, RW Tri e V347 Pup. Uma concordancia dos perfis em emissao dos modelos foi encontrada quando confrontados com os dados no caso de sistemas de alta inclina¸cao. Uma falta de fluxo nas linhas de alta ioniza¸cao Civ ¸¸1548,1551 and Nv ¸¸1238,1242, pode ser o sinal da influencia da boundary layer (BL) ou da influencia da irradia¸cao das regioes externas do vento pelo disco interno. Estas influencias seriam cruciais no caso de sistemas baixa inclina¸cao, mas sao menores no caso de sistemas de alta inclina¸cao. / We have developed a new spectral synthesis method for modeling the accretion disk of non-magnetic cataclysmic variables (CVs). The aim of this work is to analyze the continuum and line emission of disks in a wide ultraviolet (UV) spectral range. The disk is separated in concentric rings, and for each ring a wind plus disk atmosphere are calculated. The wind atmospheres are calculated consistently with a density given by Wade and Hubeny disk-atmosphere models at their base. The structure is calculated in the co-moving frame with a vertical velocity profile defined by the Eulers equation solution for the disk wind. We found that the resulting line and continuum behavior as a function of the orbital inclination is consistent with the observations. We also verify that the accretion rate changes the wind temperature, leading to corresponding trends in the intensity of lines. We found that the primary mass has a strong effect on the absorption profiles depth. It was verified that the lines profiles are strongly sensitive to the wind temperature structure and a rise of mass loss rate increases the line intensity. Selected UV data for two high orbital inclination nova-like (NL) CVs, RW Tri and V347 Pup, were confronted with synthetic spectra. The line widths and profiles are reasonably well reproduced by the models. A lack of flux in some high ionization lines (C iv ¸¸1548,1551 and Nv ¸¸1238,1242) may be the signature of the boundary layer (BL) effect and/or the irradiation of outer wind by inner disk. We also found that for high inclination systems the vertical wind structure is less important than for low inclination system models.

O desgaste é responsável por um grande número de falhas em materiais, provocando a sua substituição antecipada e consequentemente diminuindo a sua vida útil. Por isso, estudos são realizados para caracterizar os limites de utilização desses materiais, evitando assim situações catastróficas. A partir das variáveis e parâmetros envolvidos no ensaio de desgaste, é possível construir mapas que tem como finalidade direcionar para uma correta escolha do material, de acordo com a aplicação desejada, além de identificar o seu comportamento frente à determinadas condições de uso. Neste contexto, este trabalho teve como objetivo conhecer o comportamento de desgaste de nanocompósitos de alumina contendo 5% de inclusões nanométricas de zircônia, visando construir um diagrama de transição de desgaste entre os limites de combinação de velocidade de deslizamento e carga aplicada. Para isso, corpos de prova conformados na forma de pinos com uma das extremidades semiesféricas foram caracterizados quanto a dureza e tenacidade à fratura, submetidos ao ensaio de desgaste do tipo pino-no-disco com temperaturas e umidades ambientes, variando os parâmetros de velocidade e carga. As velocidades de deslizamento variaram de 1,2 m/s à 0,1 m/s e as cargas variaram de 2 N à 100 N. Os valores de dureza e tenacidade a fratura obtidos foram de 14,08 ± 1,22 GPa e 3,99 ± 0,14 MPa.m1/2, respectivamente. Os resultados de desgaste mostraram que a partir da caracterização e construção do diagrama de transição de regime de desgaste, com combinações de parâmetros extrínsecos de carga e velocidade de deslizamento, foi possível definir e atingir as condições limites entre o regime de desgaste moderado e a transição para o regime severo. Esse diagrama auxilia na seleção e comparação da transição entre os limites de desgaste do material estudado com outros tipos usados na engenharia. / Wear is responsible for a large number of material failures, causing them to be replaced early and consequently shortening their life-time. Therefore, studies are conducted to characterize the limits of use of these materials, thus avoiding catastrophic situations. From the variables and parameters involved in the wear test, it is possible to construct maps that aim to direct the correct choice of material according to the desired application, as well as to identify its behavior against certain conditions of use. In this context, the objective of this work was to know the wear behavior of alumina nanocomposites containing 5% nanometric zirconia inclusions in order to construct a simplified wear transition diagram between the sliding speed and applied load combination limits. For this, test pieces shaped like pins with semi-spherical tips were characterized in terms of hardness and fracture toughness, took to the wear test of the pin-on-disk with ambient temperatures and humidity, varying the speed and load parameters. Slip velocities ranged from 1.2 m/s to 0.1 m/s and loads ranged from 2 N to 100 N. The values of hardness and fracture toughness obtained were 14.08 ± 1.22 GPa and 3.99 ± 0.14 MPa.m1/2, respectively. The results of wear showed that from the characterization and construction of the wear regime transition diagram, with combinations of extrinsic load parameters and slip speed, it was possible to define and reach the boundary conditions between the moderate wear regime and the transition for the severe regime. This diagram helps in the selection and comparison of the transition between the wear limits of the studied material with other types used in engineering.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21572号 / 理博第4479号 / 新制||理||1643(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 野上 大作, 教授 長田 哲也, 教授 嶺重 慎 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22251号 / 理博第4565号 / 新制||理||1655(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 嶺重 慎, 准教授 前田 啓一, 教授 長田 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Glaucoma is the third most common cause of blindness in the world. There are several types of glaucomma, which makes early diagnosis of this illness harder. One posibble way for early diagnosis could be analysis of a retinal vessel pulsation. Data in this work were captured by experimental device called video ophtalmoscope. Several methods for optic disc segmentation were designed. From segmented parts, pulsation curve was recorded. Analysis of the pulsation curve was provided in two ways: Analysis of the whole pulsation curve and Averaged pulse analysis. Both methods were tested with diferent reference signals.

This diploma thesis will deal with optimization of backup system of elementary school in Židlochovice, with possibility of using own technologies or cloud services. The thesis analyzes the current state of the backup system, proposes two variants of optimization and one of them is recommended for implementation. The implementation of the selected one will be described using the Lewin‘s model of change and network diagram. The risks that may arise during implementation or operation will be highlighted and propose methods to reduce them.

In this paper is carried out basic design and calculation of tube heat exchanger with a straight tube bundle with installed systém of disk and doughnut baffles. The calculation included pressure losses and heat transfer coefficient of tubular space and shell side. Then CFD model was made for parametric study, which was focused on influence of change of the baffles geometry on the heat output of the exchanger and the pressure loses on the shell side.

The aim of this diploma thesis is to analyse loading forces which impact on the frame of the disk plough-harrow during the real operation, suggestion and assembling of the measuring system for measuring of real loading. On the basis of this measuring to accomplish structural deformational tensor analysis of the frames load-bearing’s machine. In the introduction is shortly described using of the disk plough-harrow in modern agriculture. The diploma thesis is divided into two parts. The first part is devoted to the suggestion of the measuring system and loading measuring under real working conditions. The second part is focused on deformational tensor analysis of the frames load-bearing’s machine through the method of final elements. In conclusion it follows the evaluation of gained pieces of knowledge.

The aim of this thesis was to design and implement the interactive Java applet used for topography 3D optic nerve head visualization. Primary purpose of the 3D vizualization is ophthalmology, especially for diagnosis of glaucoma. More over should serve as a training material, which enables to study the transformation of 2D figures to 3D model and to test the effects of adjustments and regulations to imaging of the model in 3D space. Two program versions were designed in this work using the development system NetBeans version 5.5. Their final realization is implemented as .html application working in web browser window. First version of the designed applet is simple intuitive application with several default settings, so that the figure is opened automatically to 3D model. Subsequently, the applet enables to set the size of the image, 3D depth of the image, smoothing of the surface and selection of monochrome or coloured image. The second version is the extension of the first version of the designed applet, and provides the possibility to display x, y, z axis, depiction of the 3D model surface by dots, curves or grid, and illumination of the surface. Software was tested on available topographic data acquired by HRT equipment and in different web browsers. Technical documentation and user’s manual are also involved in this thesis.