Made available in DSpace on 2015-03-26T13:28:41Z (GMT). No. of bitstreams: 1 texto completo.pdf: 983693 bytes, checksum: 1ff7ce64df230d8111f225afb23dbd33 (MD5) Previous issue date: 2007-03-19 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Commonly, compaction of soil specimens in laboratory is processed by dynamic (Proctor test) or static (application of constant tension to the soil) compaction tests, being common to associate similar compaction curves to both procedures. However, data from studies developed in the Civil Engineering Laboratory of the Universidade Federal de Viçosa, Viçosa, Brazil, for road engineering applications brought new inside into this hypothesis and led to this research that addresses the analysis of the influence of compaction modes and compaction parameters in the laboratory compaction curves and in the mechanical strength of two gneiss residual soils from the Zona da Mata Norte of Minas Gerais state, respectively a silty-sandy clay (Soil 1) and a clayey-silty sandy (Soil 2). This research encompassed the following aspects: (i) compaction procedures: static and dynamic compaction modes; (ii) number of specimen layers: one, two and three layers and (iii) diameter of the compaction cylinder: 35 mm, 73 mm and 100 mm. Besides that, evaluation of the influence of compaction modes in the soils specimens structures was based on analysis of data from unconfined compression tests performed in specimens compacted at pre-established water contents (hot, hot - 3% and hot + 2%) using the Standard Proctor compaction effort. Concerning engineering practical applications and based on statistical data analysis (ANOVA) conclusions are as follows: (i) there was significant influence of compaction modes on soils optimum compaction parameters; (ii) there were significant structural changes in the soils specimens due to the application of different compaction modes, as well as it was evident the importance of soils processes formation in theirs mechanical responses; (iii) regarding influence of the number of specimen layers in soil optimum compaction parameters and mechanical strength, it was observed that compaction using two and three layers led to the same results, not being recommended compaction in one layer and (iv) regarding influence of compaction mold diameter in soil optimum compaction parameters and mechanical strength, it was observed significant influence for Soil 1 (more clayey) and not significant influence for Soil 2 (more sandy). / Comumente, a compactação de corpos-de-prova de solos em laboratório processa-se por vias dinâmica (cilindro Proctor e soquete, por exemplo) ou estática (aplicação de tensão constante ao solo), sendo comum associar a estes procedimentos curvas de compactação similares. Porém, essa hipótese tem sido questionada, em especial a partir de resultados de estudos realizados com solos para fins rodoviários no Laboratório de Engenharia Civil da Universidade Federal de Viçosa, Viçosa, Brasil. O presente trabalho direcionou-se ao estudo da influência de parâmetros de moldagem de corpos-de-prova nas curvas de compactação de laboratório e na resistência mecânica de dois solos residuais de gnaisse da Zona da Mata Norte de Minas Gerais, respectivamente, de texturas argilo-areno siltosa (Solo 1) e areno-silto-argilosa (Solo 2), com abordagem dos seguintes aspectos: (i) método de compactação: métodos estático e dinâmico; (ii) número de camadas dos corpos-de-prova: uma, duas e três camadas e (iii) diâmetro do cilindro de compactação: 35 mm, 73 mm e 100 mm. Empregaram-se, além dos resultados obtidos para as curvas de compactação dos solos, resultados de ensaios de compressão não confinada realizados em corpos-de-prova compactados em teores de umidade pré-determinados [hot, (hot - 3%), (hot + 2%)], considerando-se a energia de compactação do ensaio Proctor normal, para a avaliação da ocorrência de mudanças estruturais nos solos. Para fins práticos de engenharia e com base em análise estatística (ANOVA), pode-se concluir que: (i) houve influência significativa dos elementos analisados nos parâmetros ótimos de compactação, considerando-se os modos de compactação empregados; (ii) para ambos os solos, ocorreram mudanças estruturais significativas representadas por variações na resistência à compressão não confinada dos solos analisados, evidenciando ainda a importância dos processos de formação dos solos nas suas respostas mecânicas quando compactados; (iii) quanto à influência do número de camadas dos corpos-de-prova nos parâmetros ótimos de compactação e de resistência mecânica, notou-se que a compactação em duas e três camadas levou aos mesmos resultados, não sendo recomendável a compactação em apenas uma camada e (iv) quanto à influência do diâmetro do cilindro de compactação nos parâmetros ótimos de compactação e resistência mecânica, observou-se influência significativa para o Solo 1 (mais argiloso) e não significativa para o Solo 2 (mais arenoso).

Cette thèse de doctorat s’intéresse à la fatigue des élastomères, et plus particulièrement des caoutchoucs nitrile hydrogénés (sigle HNBR en anglais). Les HNBR sont des élastomères de haute performance,classiquement utilisés pour des applications industrielles à haute température où une bonne résistance chimique aux hydrocarbures est également requise.La thèse est divisée en trois parties principales.En premier lieu, des améliorations majeures pour les expériences de durée de vie en fatigue des élastomères sont proposées. Une approche expérimentale originale permettant le pilotage des essais en contrainte vraie est détaillée.Grâce à cette méthode, la première « vraie »courbe de Wöhler (contrainte vraie en fonction du nombre de cycles) pour des élastomères est tracée. Ensuite, des outils statistiques, issus de la recherche médicale, permettent une analyse probabiliste des résultats présentant une grande dispersion et des durées de vie censurées.Dans un second temps, ces nouveaux outils sont utilisés pour étudier l'effet de la formulation chimique – les taux d’acrylonitrile et d'hydrogénation notamment - sur la résistance en fatigue du HNBR à 120 oC. Ces résultats sont complétés par des expériences de propagation de fissure de fatigue et par une analyse de l'endommagement. Finalement, l'influence du vieillissement thermique sur la résistance en fatigue du HNBR est étudiée ; deux nouveaux essais sont développés : des essais simultanés de vieillissement et de fatigue, et des expériences de fatigue sur des échantillons préalablement vieillis.De plus, la cristallisation sous tension dans le HNBR est pour la première fois étudiée de manière quantitative / The present PhD thesis is devoted to investigation of fatigue in elastomers, andmore particularly of carbon black-filled hydrogenated nitrile butadiene rubber (HNBR).HNBR is a high performance elastomer classically used for high temperature industrial applications, where high resistance to industrial solvents is also required.The thesis is divided into three main parts.First, major improvements of testing procedures utilized in fatigue life testing ofelastomers are proposed. An original method to prescribe the true stress throughout fatigue experiments is developed; it permits to plot the first “true” Wöhler curve, i.e. true stress vs.number of cycles, for elastomers. Then,statistical tools, widely applied in medical research, are adopted for a comprehensive probabilistic analysis of fatigue life results that exhibit high scatter and censored lifetimes.Second, these novel tools are used to investigate the effect of chemical formulation -acrylonitrile content, percent hydrogenation,and of a composite blend - on fatigue resistance of HNBR at the service temperature of 120 oC. In addition to these fatigue life tests,fatigue crack propagation experiments and microscopic fatigue damage analysis are carried out. Third, the influence of thermal aging on fatigue performances of HNBR is investigated.To this end, two additional fatigue life tests are carried out: simultaneous aging and fatigue experiments, and fatigue experiments on preaged samples.Additionally, strain-induced crystallization in HNBR is studied; for the first time, quantitative relationships between crystallization, strain,and stress are established for unfilled HNBR blends.

One of the major constraints limiting the efficiency of sheep production is the control of gastrointestinal nematode parasites. Parasite control by strategic use of anthelmintics is threatened by the emergence of nematode populations that are resistant to the drugs available. It is therefore increasingly apparent that steps toward maintaining sustainable productivity in the growing face of anthelmintic resistance (AR) is required by farmers. To facilitate the uptake of sustainable approaches to parasite management, a comprehensive understanding of the various factors that may influence farmers’ decision-making processes is required. In order to establish which factors are influential, and determine their impact on farmers’ roundworm control behaviours, both qualitative and quantitative research methods were used including focus groups as well as attitudinal and behavioural questionnaires. A retrospective analysis was initially conducted of historical surveys designed to identify farm specific characteristics and parasite management practices including anthelmintic usage. The objectives of the analysis were to identify factors associated with uptake of best practice advice including farm characteristics and information sourcing. In addition, the implementation of sustainable roundworm control practices was investigated using two surveys conducted in 2000 and 2010. Logistic regression models were applied for univariable and multivariable analysis of dependent and independent variables. The next step was to conduct a series of focus groups in different geographic regions of Scotland. The main purposes were to explore sheep farmers’ attitudes towards different aspects of roundworm management, as well as to identify potential motivators and barriers to uptake of sustainable parasite control practices. The findings aided in the development of an attitudinal questionnaire used to canvass opinions representative on a national level. The concluding study involved a telephone survey of 400 Scottish sheep farmers, designed to elicit attitudes regarding roundworm control, AR and sustainable roundworm control practices. A quantitative statistical analysis technique (Structural Equation Modelling) was then used to test the relationships between socio-psychological factors and the uptake of sustainable roundworm control practices. The analysis of historical questionnaire data demonstrated evidence of a shift towards the use of practices to reduce the rate of AR development, most notably a decline in the practice of ‘dose and move’ as well as an overall reduction in treatment frequency. Statistical analysis identified significant associations between farm characteristics and specific treatment strategies. For example, larger farms were more likely to adopt a set treatment regimen (P=0.036), compared with smaller farms, which were more likely to treat based on clinical signs of infection (P=0.021). Sourcing of roundworm control information primarily from veterinarians was most associated with treatment timings with no parallels between time points. From the qualitative focus group studies conducted we identified four overarching themes impacting on sheep producers’ attitudes to roundworm control and best practice advice. These themes comprised: a lack of perceived need to change, the complexity of advice, the ease of implementation of recommended practices and the effectiveness of extension approaches. Additionally, the most important and implementable guidelines identified by sheep farmers were: ‘working out a roundworm control strategy with an advisor’ and ‘administering anthelmintics effectively’ with regard to correct drenching practice i.e. appropriate dosing, administration and drug storage procedures. These findings exhibited similarities with veterinarians’ rankings with also, ‘testing for AR’, ‘preserving susceptible parasites’ and ‘reducing dependence on anthelmintics’ receiving the lowest rankings for importance and implementability. The quantitative analysis from the attitudinal/behavioural questionnaire identified eleven factors with significant influences on the adoption of sustainable roundworm control practices. The key influences on overall adoption were farmers’ baseline understanding about roundworm control and self-reported confirmation of anthelmintic resistance in their flock. Additional positive influences included, positive attitudes to veterinary services, enterprise type and perceived risk of AR. Factors that were shown to have the greatest relative effects on individual parasite control practices included; the perceived resource requirements for implementing a quarantine strategy, farmers’ AR suspicions for instigating AR testing and the confirmation of AR for adopting faecal egg count monitoring. The findings have highlighted several factors which can influence sheep farmers’ decisions to reject or adopt recommended roundworm control practices. It is evident that the perceived complexity, lack of need and practicality of the current recommendations necessitates changes to how extension is designed and disseminated to farmers. The findings also suggest that improving farmers’ acceptance and uptake of diagnostic testing and improving underlying knowledge and awareness about nematode control is a significant target to influencing adoption of best practice behaviours. The importance of veterinarians as highly-trusted information resources validates the need for further engagement with veterinarians concerning sustainable parasite control approaches, to facilitate collaboration with farmers. The need for interaction between farmers and their advisors is key to resolving the issues raised to enable the necessary explanation, justification and execution of recommended practices to suit farmers’ needs and farming conditions.

Submitted by WENDERSON NASCIMENTO LOPES (wendersonmanin@gmail.com) on 2018-06-28T19:19:09Z No. of bitstreams: 1 Dissertação_Mestrado_Wenderson_v1.8.pdf: 5519001 bytes, checksum: dd9e99dad5016a1e93e611390d52f0f7 (MD5) / Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2018-06-29T14:22:01Z (GMT) No. of bitstreams: 1 lopes_wn_me_bauru.pdf: 5538361 bytes, checksum: 642a6ec7656c00d9871f41bf870fd5f9 (MD5) / Made available in DSpace on 2018-06-29T14:22:01Z (GMT). No. of bitstreams: 1 lopes_wn_me_bauru.pdf: 5538361 bytes, checksum: 642a6ec7656c00d9871f41bf870fd5f9 (MD5) Previous issue date: 2018-05-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A dressagem é uma operação muito importante para o processo de retificação. O objetivo desta é recondicionar o rebolo para restabelecer suas características de corte perdidas devido ao desgaste produzido após sucessivos passes. Sistemas de monitoramento que utilizam emissão acústica (EA) têm sido propostos para correlacionar os sinais com diversas condições da ferramenta. Este estudo traz uma nova abordagem de processamento de sinais de EA com o objetivo de identificar o momento correto para finalizar a dressagem, o que é essencial em um sistema de controle automático. A partir dos sinais de EA, coletados em testes de dressagem de rebolo de óxido de alumínio com dressador de ponta única, a análise espectral foi realizada por meio da Densidade Espectral de Potência (PSD, Power Spectral Density), selecionando-se bandas de frequências que melhor caracterizam o processo. O parâmetro estatístico "counts" foi aplicado ao sinal original não filtrado e filtrado nas bandas selecionadas para identificar a condição da ferramenta e, por sua vez, para a implementação de um sistema de monitoramento. Os resultados mostraram uma relação expressiva entre as condições de corte da ferramenta e os sinais processados nas bandas selecionadas. Houve uma grande diferença dos sinais filtrados nas bandas selecionadas e sinais não filtrados, refletindo que os filtrados foram mais eficientes em termos de automação de processos. / Dressing is an important operation for the grinding process. Its goal is to recondition the wheel tool to re-establish its cutting characteristics, owing to the wear produced after successive passes. Monitoring systems that use acoustic emission (AE) have been studied to correlate the signals with several tool conditions. This study brings a new approach of processing AE signals with the purpose of identifying the correct moment to stop the dressing, which is essential in an automatic control system. From the AE signals collected in dressing tests with aluminium oxide grinding wheel and single-point dresser, spectral analysis was made through power spectral density, selecting frequencies bands that best characterize the process. The statistical parameter ‘counts’ was applied to the raw signal unfiltered and filtered in the selected bands in order to identify the tool condition and, in turn, towards a monitoring system implementation. Results showed an expressive relation between tool cutting conditions and processed signals in the selected bands. There was a great disparity of the filtered signals in the selected bands and signals unfiltered, reflecting that the filtered ones were more efficient in terms of process automation.

The connection between Upper Tropospheric Cyclonic Vortex (UTCV) and Brazilian Northeast Jet Stream (BNEJS) was analyzed for 9 years between 1988 and 2000, separated by El Niño, La Niña and Neutral years. Through the reanalysis products from NCEP, and METEOSAT satellite images in the infrared channel, were observed 167 UTCVs, most of them originated over the Atlantic Ocean with an average last of 4 days and showed no significant variability in years of El Niño and La Niña. Approximately 54% of the observed UTCVs were associated to air currents superior than 20m.s-1 in its periphery, these currents are called BNEJS. In El Niño years was observed an increase of BNEJS cases associated to UTCV, while in La Niña years, the number of occurrences was practically the same as in neutral years. The BNEJS showed intensitity up to 40 m.s-1, and the most observed wind directions were from south, southeast, northwest and west. Thus, 3 patterns of occurrence of BNEJS were identified, named Meridional, Zonal and Transversal. The Meridional BNEJS occurs in the UTCVs west periphery, usually over the continent, showing the upward movements between the BNEJS and the Northern Subtropical Jet Stream (NSJS). And finally, the transversal BNEJS, showed two kinds of currents, one from southeast and another from northwest. In these cases, the UTCVs axis showed an inclination to west and the upward movements were observed in the UTCVs periphery, where the winds were weaker. Thus, three cases were chosen to represent the observed patterns and investigate the vertical movements, comparing to the cloudiness in the satellite images, where was observed, in both cases, that the upward movements doesn t exists or are too weak in the jet streak BNEJS area. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A ligação entre Vórtice Ciclônico em Altos Níveis (VCAN) e a Corrente de Jato do Nordeste Brasileiro (CJNEB), foi analisada durante 9 anos entre 1988-2000, divididos em períodos de El Niño, La Niña e Neutro. Através dos produtos de reanálise do NCEP, e imagens do satélite METEOSAT no canal infravermelho, foram observados 167 VCAN s, em grande maioria originados sobre o oceano Atlântico, com uma duração média de 4 dias, não apresentando variabilidade significativa em anos de El Niño e La Niña. Dos VCAN s observados, aproximadamente 54%, estavam associados a correntes de ar superiores a 20m.s-1 em sua periferia, essas correntes são chamadas de CJNEB. Em anos de El Niño, foi observado um aumento dos casos de CJNEB associados à VCAN, enquanto que em anos de La Niña, o número de ocorrências foi praticamente o mesmo que em anos neutros. As CJNEB apresentaram intensidade de até 40 m.s-1, e as direções mais observadas foram de sul, sudeste, noroeste e oeste. Assim, foram identificados 3 padrões de ocorrência de CJNEB, denominadas de Meridional, Zonal e Transversal. A CJNEB Meridional ocorre na periferia oeste do VCAN, geralmente sobre o continente, apresentando os movimentos ascendentes no lado oeste da corrente. A CJNEB Zonal ocorreu sobre a periferia norte do VCAN, apresentando movimentos ascendentes entre a CJNEB e o Jato Subtropical do Hemisfério Norte (JSTHN). E finalmente, a CJNEB Transversal, que apresentou dois tipos de correntes, uma de sudeste e outra de noroeste. Nesses casos, o eixo do VCAN apresentou uma inclinação para oeste, e os movimentos ascendentes foram observados na periferia do VCAN, onde os ventos foram mais fracos. Assim, três casos foram escolhidos a fim de representar os padrões observados e investigar os movimentos verticais, comparando com a nebulosidade nas imagens de satélites, onde foi observado em ambos os casos, que os movimentos ascendentes inexistem ou são muito fracos na região mais intensa da CJNEB ( Jet Streak ).

Submitted by Marcus Rocha (marcus.bonaldi@gmail.com) on 2014-11-12T01:38:53Z No. of bitstreams: 1 Versão Final tese PDF.pdf: 5244046 bytes, checksum: ebbdc36061829e3c3c3043394222067c (MD5) / Approved for entry into archive by Viviane Alencar (viviane.alencar@fgv.br) on 2014-11-12T11:32:23Z (GMT) No. of bitstreams: 1 Versão Final tese PDF.pdf: 5244046 bytes, checksum: ebbdc36061829e3c3c3043394222067c (MD5) / Approved for entry into archive by Marcia Bacha (marcia.bacha@fgv.br) on 2014-11-13T13:53:37Z (GMT) No. of bitstreams: 1 Versão Final tese PDF.pdf: 5244046 bytes, checksum: ebbdc36061829e3c3c3043394222067c (MD5) / Made available in DSpace on 2014-11-13T13:53:46Z (GMT). No. of bitstreams: 1 Versão Final tese PDF.pdf: 5244046 bytes, checksum: ebbdc36061829e3c3c3043394222067c (MD5) Previous issue date: 2010-07-05 / This work investigates and analyzes the differences between inflation’s annual rates and the forecasts by economic agents, for a year ahead. The inflation index examined, were the IPCA, IPA-M, IGP-M and IGP-DI. For each agents preview, for each index, we performed a statistical analysis and time series analysis, by ARIMA model. Through this model we understood the forecast errors of economic agents by the past values of forecast errors in the past, besides the stochastic terms. / Este trabalho investiga e analisa as diferenças das taxas anuais de inflação realizadas com relação às previsões dos agentes econômicos do mercado para um ano à frente. Os índices analisados foram o IPCA, IPA-M, IGP-M e o IGP-DI. Referente à previsão dos agentes para cada índice, foi feito uma análise estatística e uma análise de séries temporais através do modelo ARIMA. Este último explicou o erro de previsão dos agentes econômicos através de valores passados, ou defasados, do próprio erro de previsão, além dos termos estocásticos.

Cette thèse se concentre sur l'analyse de données présentées sous forme de mesures de probabilité sur R^d. L'objectif est alors de fournir une meilleure compréhension des outils statistiques usuels sur cet espace muni de la distance de Wasserstein. Une première notion naturelle est l'analyse statistique d'ordre un, consistant en l'étude de la moyenne de Fréchet (ou barycentre). En particulier, nous nous concentrons sur le cas de données (ou observations) discrètes échantillonnées à partir de mesures de probabilité absolument continues (a.c.) par rapport à la mesure de Lebesgue. Nous introduisons ainsi un estimateur du barycentre de mesures aléatoires, pénalisé par une fonction convexe, permettant ainsi d'imposer son a.c. Un autre estimateur est régularisé par l'ajout d'entropie lors du calcul de la distance de Wasserstein. Nous nous intéressons notamment au contrôle de la variance de ces estimateurs. Grâce à ces résultats, le principe de Goldenshluger et Lepski nous permet d'obtenir une calibration automatique des paramètres de régularisation. Nous appliquons ensuite ce travail au recalage de densités multivariées, notamment pour des données de cytométrie de flux. Nous proposons également un test d'adéquation de lois capable de comparer deux distributions multivariées, efficacement en terme de temps de calcul. Enfin, nous exécutons une analyse statistique d'ordre deux dans le but d'extraire les tendances géométriques globales d'un jeu de donnée, c'est-à-dire les principaux modes de variations. Pour cela nous proposons un algorithme permettant d'effectuer une analyse en composantes principales géodésiques dans l'espace de Wasserstein. / This thesis focuses on the analysis of data in the form of probability measures on R^d. The aim is to provide a better understanding of the usual statistical tools on this space endowed with the Wasserstein distance. The first order statistical analysis is a natural notion to consider, consisting of the study of the Fréchet mean (or barycentre). In particular, we focus on the case of discrete data (or observations) sampled from absolutely continuous probability measures (a.c.) with respect to the Lebesgue measure. We thus introduce an estimator of the barycenter of random measures, penalized by a convex function, making it possible to enforce its a.c. Another estimator is regularized by adding entropy when computing the Wasserstein distance. We are particularly interested in controlling the variance of these estimators. Thanks to these results, the principle of Goldenshluger and Lepski allows us to obtain an automatic calibration of the regularization parameters. We then apply this work to the registration of multivariate densities, especially for flow cytometry data. We also propose a test statistic that can compare two multivariate distributions, efficiently in terms of computational time. Finally, we perform a second-order statistical analysis to extract the global geometric tendency of a dataset, also called the main modes of variation. For that purpose, we propose algorithms allowing to carry out a geodesic principal components analysis in the space of Wasserstein.

Aim of the thesis The aim of this thesis is to show usage of analysis of basic and advanced statistics to evaluate the game performance in ice-hockey. Using this analysis can be more accurate because it is based on facts. This statement is compared with evaluation of the game performance by the experts that used direct observing method. The main aim of this thesis is to bring this idea to the Czech ice-hockey community which can be helpful to improve the club hockey in Czech Republic or improve Czech ice-hockey itself. Methods of thesis The method of analysis of statistical data to evaluate the game performance is used in this diploma thesis. Statistical data were acquired by indirect watching of video records of the games. This analysis is compared with method of direct observing of the game to evaluate the game performance which was used by experts. Conclusion By analyzing current situation in evaluating the game performance it was found out that many teams are still using method of direct observing to evaluate the game performance. In practical part of the thesis the experts after using method of direct observing of the game came up with different conclusions. In comparison with statistical analysis conclusions of the experts are not based on facts. In the discussion the experts talk that...

Ce travail de thèse introduit une nouvelle méthode pour la caractérisation radiologique des déchets très faiblement radioactifs produits au sein de l’Organisation Européenne pour la Recherche Nucléaire (CERN). La méthode se base sur : 1. le calcul des radionucléides en présence, i.e. les radionucléides qui peuvent être produits lors de l’interaction des particules avec la matière et les structures environnantes les accélérateurs, 2. la mesure directe des émetteurs gamma et, 3. la quantification des émetteurs alpha et beta purs et de rayons X de faible énergie, appelés radionucléides difficile-a-mesurer (DTM), en utilisant les méthodes dites des «scaling factor» (SF), «correlation factor» (CF) et activité moyenne (MA). La première phase du processus de caractérisation est le calcul des radionucléides en présence à l’aide de codes de calcul analytiques ou Monte Carlo. Après le calcul de l’inventaire radiologique, les radionucléides émetteurs gamma sont mesurés par spectrométrie gamma dans chaque colis de la population. L’émetteur gamma dominant, appelé « key nuclide » (KN), est identifié. La méthode dite des «scaling factors» permet d’estimer l’activité des radionucléides DTM après évaluation de la corrélation entre l’activité des DTM et l’activité de l’émetteur gamma dominant obtenue à partir d’échantillons. Si une corrélation existe, l’activité des radionucléides DTM peut être évaluée grâce à des facteurs de corrélation expérimentaux appelés « scaling factors », sinon l’activité moyenne obtenue à partir d’échantillons prélevés dans la population est attribuée à chaque colis. Lorsque les activités des émetteurs alpha et beta purs et des émetteurs X de faible énergie ne peuvent pas être estimées par mesure la méthode des « correlation factors » s’applique. La méthode des « correlation factors » se base sur le calcul de corrélations théoriques entre l’émetteur gamma dominant et les radionucléides de très faible activité. Cette thèse décrit en détail la nouvelle technique de caractérisation radiologique, montre un cas d’application complet et présente les résultats de l’industrialisation de la méthode ayant permis la caractérisation radiologique de plus de 1000 m3 de déchets radioactifs au CERN entre 2015 et 2017. / This thesis introduces a new method to characterize metallic very-low-level radioactive waste produced at the European Organization for Nuclear Research (CERN). The method is based on: 1. the calculation of a preliminary radionuclide inventory, which is the list of the radionuclides that can be produced when particles interact with a surrounding medium, 2. the direct measurement of gamma emitters and, 3. the quantification of pure-alpha, pure-beta and low-energy X-ray emitters, called difficult-to-measure (DTM) radionuclides, using the so-called scaling factor (SF), correlation factor (CF) and mean activity (MA) techniques. The first stage of the characterization process is the calculation of the radionuclide inventory via either analytical or Monte Carlo codes. Once the preliminary radionuclide inventory is obtained, the gamma-emitting radionuclides are measured via gamma-ray spectrometry on each package of the waste population. The major gamma-emitter, called key nuclide (KN), is also identified. The scaling factor method estimates the activity of DTM radionuclides by checking for a consistent and repeated relationship between the key nuclide and the activity of the difficult to measure radionuclides from samples. If a correlation exists the activity of DTM radiodionuclides can be evaluated using the scaling factor otherwise the mean activity from the samples collected is applied to the entire waste population. Finally, the correlation factor is used when the activity of pure-alpha, pure-beta and low-energy X-ray emitters is so low that cannot be quantified using experimental values. In this case a theoretical correlation factor is obtained from the calculations to link the activity of the radionuclides we want to quantify and the activity of the key nuclide. The thesis describes in detail the characterization method, shows a complete case study and describes the industrial-scale application of the characterization method on over 1’000 m3 of radioactive waste, which was carried out at CERN between 2015 and 2017.

O uso de Ambientes Virtuais (AVs) não-imersivos em educação ainda não foi devidamente explorado e estudado, porém alguns autores já demonstram a diferença que a Realidade Virtual (RV) pode fazer no aprendizado. A linguagem Virtual Reality Modeling Language (VRML) é uma proposta para a introdução de AVs não-imersivos na internet; é uma linguagem independente de plataforma, que permite a criação de AVs por onde se pode passear, visualizar objetos por ângulos diferentes e com eles interagir. Assim, os estudantes podem beneficiar-se dessa tecnologia, pois ela lhes permite acessar objetos que descrevem assuntos e contextos do conteúdo abordado e informações verbal-escritas da disciplina, podendo manuseá-los. Este trabalho possui três partes: na primeira, investigam-se as questões que envolvem o uso de AVs no ensino-aprendizagem de matemática para o desenvolvimento dos aspectos cognitivos; as experiências e as condições necessárias para o uso dessa tecnologia na educação de matemática, como a construção do conhecimento e o desenvolvimento de aspectos cognitivos e lógico-matemáticos. Na segunda parte, propõe-se um modelo conceitual de um ambiente de aprendizagem para o ensino-aprendizagem de matemática, sendo, após, realizada a implementação do ambiente de aprendizagem proposto. A terceira parte reporta um estudo de caso, no qual um AV modelado em VRML é aplicado aos alunos de uma escola. Alguns dados dessa aplicação são levantados e analisados estatisticamente com o fim de se avaliar o desempenho do uso do protótipo no ensino-aprendizagem de matemática. / The use of non-immersive virtual environments in education has not been studied, as it should have been. However, some authors have already demonstrated the benefits coming from using such technology. VRML - Virtual Reality Modeling Language provides means for using virtual environments in the Internet. It is a platformindependent language that allows the specification of virtual environments where users can walk in, observe different objects and interact with them. Students can benefit from this technology, since it allows them to access objects describing subjects that students should study. This work is presented in three parts. In the first one, we investigate the use of virtual environments in math education for developing cognitive aspects, the experiences and necessary conditions for using this technology in improving logic and mathematical thinking. In the second part, we present both the conceptual model and the implementation of an educational tool intended to help in math education. The third part is a case study: we have developed a virtual environment using VRML, and it has been applied in math classes for 7th grade students. Data collected during this experiment has been analyzed statistically and some conclusions can be drawn based on those results, and observations.