A new generation of compact and highly efficient power production and propulsion technologies are critically needed in enabling NASAs long-term goals. Nuclear fission power technologies as part of project Prometheus are in development to meet this need. Proposed reactor concepts utilize a combination of refractory metals and stainless steels. One such refractory alloy, Niobium 1% Zirconium (Nb-1Zr), will be used because of its strength at high temperatures, neutron absorption properties, and resistance to corrosion by liquid alkali metals. One potential problem in using Nb-1Zr is that it undergoes rapid high temperature oxidation, even in low oxygen concentrations. Long-term oxidation of the niobium matrix can significantly deteriorate the mechanical properties of the alloy. This thesis reports on experimental studies of the high temperature interaction of 316 stainless steel (316 SS) and Nb-1Zr under prototypic space fission reactor operating conditions. Specifically, how the high temperature oxidation rate of Nb-1Zr changes when in contact with 316 SS at low external oxygen concentrations. The objective of the project is to determine if transport of gaseous contaminants, such as oxygen, will occur when Nb-1Zr is in contact with 316 SS, thereby increasing the oxidation rate and degrading material properties. Experiments were preformed in a realistic non-nuclear environment at the appropriate operating conditions. Thermal Gravimetric Analysis techniques were used to quantify results. Coupons of Nb-1Zr and Nb-1Zr in contact with 316 SS foil are subjected to flowing argon with oxygen concentrations between 4-15ppm and heated to a temperature of 500, 750, and 1000oC for 2 to 10 hours. Experiments were conducted at the Early Flight Fission Test Facility at NASA Marshall Space Flight Center. The experimental results indicate that a complex oxidation process, which depends greatly on temperature and oxygen concentration, occurs at the expected operating conditions. Non-linear regression techniques were applied to experimental data in order to derive correlations for the approximate oxidation rate of Nb-1Zr and Nb-1Zr in contact with 316 SS as a function of time, temperature, and oxygen concentration.

Ce mémoire a pour objectif de vérifier si la culture populaire, plus particulièrement le cinéma, nous permet de mieux comprendre la décision de lancer et de maintenir le programme spatial américain. Plus précisément, ce mémoire s'interroge sur le lien pouvant exister entre les représentations identitaires véhiculées dans les films analysés et celles mises de l'avant par les dirigeants américains afin de justifier cette décision coûteuse, au sens monétaire et politique. L'argument central affirme qu'un parallèle peut être établi entre le mythe de la frontière et la destinée manifeste, perceptibles dans le cinéma précédant l'alunissage, et les discours des dirigeants américains entre 1961 et 1969. Autrement dit, nous jugerons que la mise en place réussie d'un processus d'interpellation a permis à la population de se reconnaître dans les discours institutionnalisés, et a pu faciliter l'acceptation de la décision comme conforme à ce qu'elle était et ce qu'elle devait faire. L'analyse se fait donc en deux temps. La première partie vise à faire une analyse discursive de trois films de science-fiction, sortis entre 1950 et 1969 et pouvant donc avoir fourni des arguments pour le lancement et le maintien du programme spatial américain. Nous nous chargerons donc d'étudier les dialogues, les images, les sons et les symboles présentés dans Destination Moon (1950), Forbidden Planet (1956) et 2001 : A Space Odyssey (1968), de manière à déterminer si les mythes de la frontière et de la destinée manifeste sont représentés dans le film et s'ils contribuent à fournir une image positive du programme spatial. La deuxième étape sera de vérifier si ces représentations identitaires ont su trouver écho chez les dirigeants américains cherchant à justifier le programme spatial américain. Nous procéderons donc à l'analyse de discours donnés par Kennedy, Johnson, Nixon et par certains administrateurs de la NASA. Nous concluons, sur la base de nos analyses, que la rhétorique romantique hollywoodienne a été reprise par les dirigeants américains, possiblement dans une optique de mieux vendre le projet à la société américaine. En usant d'arguments similaires à ceux présentés dans la culture populaire, les dirigeants sont parvenus à mettre en place un processus d'interpellation réussi, rendant incidemment le programme spatial plus attrayant aux yeux de la population. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : États-Unis, programme spatial, culture populaire, mythe de la frontière, destinée manifeste

This work serves to present the background, approach, and selected results for the initial master thesis and prototyping phase of Open Space, a joint visualization software development project by National Aeronautics and Space Administration (NASA), Linköping University (LiU) and the American Museum of Natural History (AMNH). The thesis report provides a theoretical introduction to heliophysics, modeling of space weather events, volumetric rendering, and an understanding of how these relate in the bigger scope of Open Space. A set of visualization tools that are currently used at NASA and AMNH are presented and discussed. These tools are used to visualize global heliosphere models, both for scientific studies and for public presentations, and are mainly making use of geometric rendering techniques. The paper will, in detail, describe a new approach to visualize the science models with volumetric rendering to better represent the volumetric structure of the data. Custom processors have been developed for the open source volumetric rendering engine Voreen, to load and visualize science models provided by the Community Coordinated Modeling Center (CCMC) at NASA Goddard Space Flight Center (GSFC). Selected parts of the code are presented by C++ code examples. To best represent models that are defined in non-Cartesian space, a new approach to volumetric rendering is presented and discussed. Compared to the traditional approach of transforming such models to Cartesian space, this new approach performs no such model transformations, and thus minimizes the amount of empty voxels and introduces less interpolation artifacts. Final results are presented as rendered images and are discussed from a scientific visualization perspective, taking into account the physics representation, potential rendering artifacts, and the rendering performance.

Made available in DSpace on 2014-06-12T15:52:09Z (GMT). No. of bitstreams: 1 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / O sucesso de um software depende diretamente de sua qualidade. Tradicionalmente, métodos formais e de inspeção manual de código são usados para assegurá-la. Tais métodos, geralmente, possuem um custo elevado e demandam bastante tempo. Dessa forma, as atividades de teste devem ser planejadas cuidadosamente para evitar o desperdício de recursos. Atualmente, as organizações estão buscando maneiras rápidas e baratas de detectar defeitos em softwares. Porém, mesmo com todos os avanços dos últimos anos, o desenvolvimento de software ainda é uma atividade que depende intensivamente do esforço e do conhecimento humano. Muitos pesquisadores e organizações estão interessados em criar um mecanismo capaz de prever automaticamente defeitos em softwares. Nos últimos anos, técnicas de aprendizagem de máquina vêm sendo utilizadas em diversas pesquisas com esse objetivo. Este trabalho investiga e apresenta um estudo da viabilidade da aplicação de métodos de aprendizagem de máquina na detecção de módulos de software propensos a falhas. Classificadores como redes neurais artificiais e técnicas de aprendizagem baseada em instâncias (instance-based learning) serão usadas nessa tarefa, tendo como fonte de informação as métricas de software retiradas do repositório do Metrics Data Program (MDP) da NASA. Também será apresentado um conjunto de melhorias, propostas durante este trabalho, para alguns desses classificadores. Como a detecção de módulos defeituosos é um problema sensível a custo, este trabalho também propõe um mecanismo capaz de medir analiticamente o custo de cada decisão tomada pelos classificadores

Orientadores: Roberto Funes Abrahão, Mauro José Andrade Tereso / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-09T17:13:35Z (GMT). No. of bitstreams: 1 Braga_CelsodeOliveira_M.pdf: 3029826 bytes, checksum: 206451bcec273e9a42df53573d3a3a39 (MD5) Previous issue date: 2007 / Resumo: A exigência por produtos com boa qualidade e segurança alimentar faz com que o beneficiamento pós-colheita se constitua numa atividade em grande expansão no Brasil. A tomaticultura representa um dos maiores mercados agrícolas brasileiros. O Brasil produz cerca de três milhões de toneladas por ano, sendo dois milhões de toneladas de tomate de mesa. Mais de dez mil produtores e sessenta mil famílias de trabalhadores estão envolvidos nesta produção, o que pode significar duzentos mil empregos diretos. Após a colheita dos tomates, a maior parte da produção é limpa, classificada e embalada em unidades de beneficiamento. Este estudo teve como objetivo a avaliação das exigências laborais nas unidades de beneficiamento de tomate de mesa sob o ponto de vista da ergonomia. Foram selecionadas 06 unidades de beneficiamento de tomate de mesa por amostragem intencional. Aplicou-se o método da Análise Ergonômica do Trabalho para identificação dos postos de trabalho com as maiores exigências laborais no processo de produção. Na pesquisa de campo envolvendo 57 operadores, utilizou-se o Método NASA TLX e o Questionário de Avaliação Visual (QAV), um questionário baseado na Escala de Likert, para avaliar, respectivamente, as exigências mentais e físicas e as exigências visuais das tarefas. Os resultados mostraram exigência mental elevada para 54,3% e exigência física alta para 20,0% dos operadores. Na avaliação da exigência visual constatou-se que 16,3% dos operadores pesquisados apresentaram fadiga visual. Comprovou-se que as exigências laborais, nos postos de trabalho estudados, estão relacionadas ao nível tecnológico dos equipamentos, grau de mecanização no processo de produção, projeto e layout do galpão, aos fatores ambientais e à organização do trabalho nas UB / Abstract: The requirement for good quality products and food safety makes of the processing after harvest an activity in great expansion in Brazil. Tomato cropping represents one of the biggest agricultural markets in Brazil. The country produces about three million tons of tomatoes per year, two million of which are intended for fresh consumption. More than ten thousand producers and sixty thousand families of workers are involved in this production, what may represent two hundred and thousand jobs. After the harvest of tomatoes, the biggest part of the production is cleaned, classified and packed in packing house units. The aim of this research was to evaluate the labor demands in the packing house units of fresh market tomatoes under the point of view of ergonomics. Six packing house units of fresh market tomatoes were selected by intentional sampling technique. It was applied the Ergonomic Analysis of Work method in order to identify the workplaces with the biggest labor demands in the production process. In the field research involving 57 workers, it was applied the NASA TLX method along with a questionnaire based on the Likert Scale in order to evaluate both mental and physical demands as well as visual demands of the tasks. The results showed high mental demand for 54.3% of the workers and high physical demand for 20.0% of them. Concerning to visual demand, it was evidenced that 16.3% of the workers presented visual fatigue. It was evidenced that the workload of the studied workplaces is related to the technological level of the equipment, mechanization degree of the production process, layout and project of the processing house, environmental factors as well as the work organization of the packing house / Mestrado / Planejamento e Desenvolvimento Rural Sustentável / Mestre em Engenharia Agrícola

The work described in this thesis is part of the initial development of the open-source visualization software OpenSpace, a collaborative project between Linköping University (LiU), the National Aeronautics and Space Administration (NASA) and the American Museum of Natural History (AMNH). The report covers the background and implementation of a rendering system that enables OpenSpace to interactively visualize multiple overlapping space weather events. The system works much like a Deferred Renderer by rendering all objects once and then resolves the final image in a second rendering step. To render a mix of opaque and translucent objects and volumes simultaneously, order-independent transparency solutions are implemented. Performance is compared against traditional methods and possible improvements are discussed. The implemented rendering system is currently powering the OpenSpace visualizations, this gives scientists an interactive tool for studying multiple space weather events, education and public outreach.

OpenSpace is an interactive data visualization software system that portrays the entire known universe in a 3D simulation. Current navigation interface requires explanations, which prohibits OpenSpace to be displayed effectively in public exhibitions. Research has been shown that using large tangible touch surfaces with a multi-touch navigation interface is more engaging to users than mouse and keyboard as well as enhances the understanding of navigation control, thus decreasing the required instructions to learn the systems user interface. This thesis shows that combining a velocity-based interaction model together with a screen-space direct-manipulation formulation produces a user-friendly interface. Giving the user precise control of objects and efficient travels in between in the vastness of space. This thesis presents the work of integrating a multi-touch navigation interface with a combined formulation of velocity-based interaction and screen-space direct-manipulation into the software framework OpenSpace.

Tidigare forskning har påvisat att ERP-system och komplexa system överlag lider av användbarhetsproblem och låg användarupplevelse. Eftersom ERP-system måste bearbeta och integrera stora mängder av data ställer det ännu högre krav på användbarhet och användarupplevelse när användare vill få åtkomst till denna data via mobila enheter. PACMAD modellen som är en relativt ny användbarhet modell bygger vidare på tidigare etablerade modeller såsom ISO-standarden och Nielsens teorier om användbarhet och kompletterar några av de brister som existerande användbarhetsmodeller har gällande mobila applikationer. Modellen bygger på befintliga teorier i användbarhet men är anpassad speciellt för applikationer som används på mobila enheter. PACMAD-modellen innehåller samtliga attribut för både ISO-standarden och Nielsens modell men introducerar även attributet kognitiv belastning som är av särskild betydelse för mobila applikationer. För att besvara vår frågeställning utfördes workshops och intervjuer hos två leverantörer av ERP-modulen Field Service Management. Utifrån resultatet från dessa utfördes användbarhetstester med slutanvändare från båda leverantörer i form av observation test för att mäta dess effektivitet och verkningsgrad och NASA task load test för att mäta applikationernas kognitiva belastning. Resultatet påvisade att deras befintliga applikation led av stora användbarhetsproblem samt att utformningen av applikationerna beaktade inte faktorer såsom användare, kontext och uppgift. De upptäckter som gjordes i bidrog till framtagning av en ny prototyp med hjälp av etablerade designmönster och PACMAD-modellen som ställdes mot existerande litteratur, testades igen samt jämfördes med deras befintliga applikation. Detta utgjorde studiens huvudsakliga resultat att navigationen bestod av för många steg, att det fanns avsaknad av funktionalitet och hög kognitiv belastning. De nyckelord som var huvudsakliga för slutsatsen var “konsekvens”, “tydlighet” och “struktur” och förklarar designprocessen som utgjorde många upptäckter där företagen inte följde etablerade designmönster eller användbarhet modeller. Dessa nyckelord ägde stor tyngd för att öka användbarhet och användarupplevelse.

Unmanned aerial systems (UASs) have a great potential to enhanced situational awareness in public safety operations. Many UASs operating in the same airspace can cause mid-air collisions. NASA and the FAA are developing a UAS traffic management (UTM) system, which could be used in public safety operations to manage the UAS airspace. UTM relies on an existing communication backhaul, however natural disasters may disrupt existing communications infrastructure or occur in areas where no backhaul exists. This thesis outlines a robust communications alternative that interfaces a fleet of UASs with a UTM service supplier (USS) over a mesh network. Additionally, this thesis outlines an algorithm for vehicle-to-vehicle discovery and communication over the mesh network.

No description available.