<p> This thesis is concerned with investigating point processes and the numerous methods available for obtaining information about them. </p> / Thesis / Master of Science (MSc)

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In the field of aeronautics (Aircraft, helicopters, space launchers...), as in the field of the automobile, reducing the harmful effects of acoustics constitutes a major concern at the international level and justifies the call for further research. With these challenges in mind, the manufacturers have expressed the need for simple models immediately available as early as the stage of preliminary drafts. This Master's Thesis presents the study and the validation of three different approaches to meet this industrial need. The first approach is based on the propagation of waves in the structure; the second approach uses the technique of SEA by calculating the equivalent damping; and the last approach uses the modal technique.In the three approaches, the transfer matrix method has been used to study the succession of layers. Applying these approaches to some aircraft structures confirm their relevance in relation to more exact and costly methods, such as the finite elements method.

This thesis includes a body of work that explores our visual relationship to the physical spaces and places we inhabit in our everyday lives. Today we live in a complex world where we are bombarded with fragments of information and inundated with distractions. As designers, we are equipped with tools and methods that allow us to experience and interpret our environment through multi-faceted perspectives and from different viewpoints. My approach to graphic design adopts techniques and practices from a mix of different disciplines. The work focuses on a design process that alternates between the parallel depiction of first-person and third-person vantage points mediated through contemporary technologies.

Atualmente, a caracterização dos resíduos radioativos gerados na operação do reator nuclear de pesquisas IEA-R1 está em curso. O reator IEA-R1 é um reator do tipo piscina aberta, moderado e refrigerado por água leve, utilizando dois leitos de resinas de troca iônica e de carvão ativado para purificação de água de refrigeração. Estes meios filtrantes são substituídos quando já não são capazes de manter a qualidade da água dentro dos limites exigidos e são tratados como rejeitos radioativos. Contendo produtos de fissão, ativação e actinídeos que escapam do núcleo do reator para a água da piscina, apresentam altas taxas de dose devido à quantidade de emissores gama de meias-vidas curtas e intermediárias, emissores alfa, elementos transurânicos de meia-vida longa bem como emissores beta puros. A caracterização destes rejeitos, consequentemente, requer métodos de análise radioquímica que incluem a amostragem e o processamento das amostras, resultando em doses elevadas para os trabalhadores. Nesse contexto, o objetivo deste trabalho consistiu em correlacionar os resultados das análises radioquímicas de amostras de rejeitos, com os resultados das medições radiométricas, utilizando a modelagem das taxas de dose em diferentes distâncias da superfície dos embalados. As taxas de dose medidas foram comparadas com os resultados de cálculos . Massa, volume e geometria das fases sólidas e líquidas de cada um dos tambores também foram determinadas, uma vez que o teor de água varia amplamente entre diferentes tambores, e são essenciais para estimar as atividades totais em cada tambor. / The characterization of the radioactive wastes generated in the operation of the nuclear research reactor IEA-R1 is currently ongoing. The IEA-R1 is an open pool type reactor, moderated and cooled by light water that uses two beds of ion-exchange resins and activated charcoal to remove impurities from the cooling water. These filter media are replaced when they are no longer able to maintain water quality within the required limits and are treated as radioactive waste. They contain the actinides and the fission and activation products that leaked into the reactor pool water. They give off high dose rates due to the amount of gamma-emitters present and are a long-term radiation safety concern because of their content of long-lived alpha- and beta-emitters. The characterization of these wastes requires radiochemical analysis methods, which include the sampling and processing of samples, resulting in high exposure to the workers. The objective of this study was to correlate the results of activity concentrations obtained in previous radiochemical analyses with the results of measurements of dose rates at various distances from the package surfaces, aiming at reducing the exposure of personnel by avoiding more sampling and sample analysis operations. Mass, volume and geometry of solid and liquid phases of each drum, which vary widely among different drums, were also estimated and use to determine total activity. The measured and calculated dose rates were compared to confirm the activity estimates.

A utilização do sistema LiDAR na obtenção de dados da superfície da Terra vem se disseminando cada vez mais pelo alto desempenho na aquisição da informação e pela efetiva utilização dos produtos e subprodutos. Diversos segmentos passaram a adotar os produtos LiDAR como insumo básico e fundamental em suas rotinas de trabalho e estudos. O sucesso em um projeto que envolve aquisição e utilização desse tipo de dado está atrelado diretamente à definição e seu planejamento. O usuário deve ser capaz de definir o escopo básico e as diretrizes técnicas fundamentais que irão garantir que a demanda final seja alcançada. Diante disto se faz necessário elaborar um planejamento estabelecendo a melhor configuração para a aquisição dos dados e também os tipos de informações que serão extraídas destes produtos. Referente ao primeiro aspecto pode-se dizer que este é a base para a todo o projeto. Por meio dele é garantido a obtenção de produtos conforme a necessidade do usuário (resoluções espaciais dos produtos, o nível de detalhamento dos objetos, representação da topografia e outros). Muitos dos usuários que contratam serviços de perfilamento LiDAR não possuem embasamento técnico suficiente para definir a melhor especificação a ser adotada. Isto faz com que a maioria deles opte por adquirir uma alta densidade de pontos que, muitas vezes é desnecessária e ainda que atendam à demanda final tornam o projeto financeiramente oneroso. Esta pesquisa mostra que para um ambiente urbano regular, nuvens de pontos com baixas densidades (4 pts/m² e 8 pts/m²) apresentam uma equivalência na qualidade geométrica para produtos e subprodutos obtidos que serão utilizados para determinadas aplicações, não havendo a necessidade de utilizar nuvens com uma alta densidade (16 pts/m²) em projetos que utilizam estes dados em estudos altimétricos: geração do Modelo Digital de Terreno, curvas de nível, pontos cotados e também planimétricos: Modelo Digital de Elevação (Superfície e Normalizada) e seus derivados (altura e contorno de objetos, imagem de intensidade, cobertura vegetal e outros). / The use of the LiDAR system in obtaining data from the Earth\'s surface has been increasingly disseminated by the high performance in the acquisition of information and the effective use of products and by-products. Several segments started to adopt LiDAR products as basic and fundamental input in their works and studies. Success in a project that involves the acquisition and use of this type of data is directly linked to the definition and its planning. The user must be able to define the basic scope and the fundamental technical guidelines that will guarantee that the final demand is reached . In view of this, it is necessary to prepare a planning establishing the best configuration for the data acquisition and also the types of information that will be extracted from these products. Regarding the first aspect can be said that this is the basis for the whole project. Through it is guaranteed to obtain products according to the user is needs (spatial resolutions of the products, the level of detail of the objects, representation of the topography and others). Many of the users who hire LiDAR profiling services do not have sufficient technical background to define the best specification to adopt. This makes the majority of them choose to acquire a high density of points that is often unnecessary and even if they meet the final demand make the project financially costly. This research shows that for a regular urban environment, low point density clouds (4 pts/m² and 8 pts/m²) present an equivalence in the geometric quality for products and by-products obtained that will be used for certain applications. The need to use clouds with a high density (16 pts/m²) in projects that use this data in altimetric studies: generation of Digital Terrain Model, contourlines, quoted points and also planimetric: Digital Elevation Model (Surface and Normalized) and its derivatives (height and contour of objects, intensity image, vegetation cover and others).

To provide point-to-point output motions needed for automation, intermittent indexing tables have widely been employed in various industries. For ensuring adequate production volume and profit margins, such devices are usually required to accurately generate intermittent motions as rapidly as possible. As a result, both of the positioning time and residual vibration are major concerns with the design of a fast, intermittent indexing table. A procedure that can be used to synthesize motor motion curves with minimized positioning time for intermittent indexing tables at high speeds is presented. First, based on the measured dynamic characteristic of an indexing table, it is then simulated to derive the equations of motion. Subsequently, favorable parameters for defining asymmetrical motor motion commands by S-curves for the modeled indexing table with improved kinematic and dynamic performance are identified. To verify the accuracy and effectiveness of the proposed approach, numerical and experimental results are revealed and compared to those obtained by using the traditional method.

This research is mainly about autonomously navigation of an agricultural wheeled mobile robot in an unstructured outdoor setting. This project has four distinct phases defined as: (i) Navigation and control of a wheeled mobile robot for a point-to-point motion. (ii) Navigation and control of a wheeled mobile robot in following a given path (path following problem). (iii) Navigation and control of a mobile robot, keeping a constant proximity distance with the given paths or plant rows (proximity-following). (iv) Navigation of the mobile robot in rut following in farm fields. A rut is a long deep track formed by the repeated passage of wheeled vehicles in soft terrains such as mud, sand, and snow. To develop reliable navigation approaches to fulfill each part of this project, three main steps are accomplished: literature review, modeling and computer simulation of wheeled mobile robots, and actual experimental tests in outdoor settings. First, point-to-point motion planning of a mobile robot is studied; a fuzzy-logic based (FLB) approach is proposed for real-time autonomous path planning of the robot in unstructured environment. Simulation and experimental evaluations shows that FLB approach is able to cope with different dynamic and unforeseen situations by tuning a safety margin. Comparison of FLB results with vector field histogram (VFH) and preference-based fuzzy (PBF) approaches, reveals that FLB approach produces shorter and smoother paths toward the goal in almost all of the test cases examined. Then, a novel human-inspired method (HIM) is introduced. HIM is inspired by human behavior in navigation from one point to a specified goal point. A human-like reasoning ability about the situations to reach a predefined goal point while avoiding any static, moving and unforeseen obstacles are given to the robot by HIM. Comparison of HIM results with FLB suggests that HIM is more efficient and effective than FLB. Afterward, navigation strategies are built up for path following, rut following, and proximity-following control of a wheeled mobile robot in outdoor (farm) settings and off-road terrains. The proposed system is composed of different modules which are: sensor data analysis, obstacle detection, obstacle avoidance, goal seeking, and path tracking. The capabilities of the proposed navigation strategies are evaluated in variety of field experiments; the results show that the proposed approach is able to detect and follow rows of bushes robustly. This action is used for spraying plant rows in farm field. Finally, obstacle detection and obstacle avoidance modules are developed in navigation system. These modules enables the robot to detect holes or ground depressions (negative obstacles), that are inherent parts of farm settings, and also over ground level obstacles (positive obstacles) in real-time at a safe distance from the robot. Experimental tests are carried out on two mobile robots (PowerBot and Grizzly) in outdoor and real farm fields. Grizzly utilizes a 3D-laser range-finder to detect objects and perceive the environment, and a RTK-DGPS unit for localization. PowerBot uses sonar sensors and a laser range-finder for obstacle detection. The experiments demonstrate the capability of the proposed technique in successfully detecting and avoiding different types of obstacles both positive and negative in variety of scenarios.