Thermonuclear fusion may become an attractive future power source. The most promising of all fusion machine concepts is the tokamak. Despite decades of active research, still huge tasks remain before a fusion power plant can go online. One of these important tasks deals with the interaction between the fusion plasma and the reactor wall. This work focuses on how eroded wall materials of different origin and mass are transported in a tokamak device. Element transport can be examined by injection of certain species of unique and predetermined origin, so called tracers. Tracer experiments were conducted at the TEXTOR tokamak before its final shutdown. This offered an unique opportunity for studies of the wall and other internal components: For the first time it was possible to completely dismantle such a machine and analyse every single part of reactor wall, obtaining a detailed pattern of material migration. Main focus of this work is on the high-Z metals tungsten and molybdenum, which were introduced by WF6 and MoF6 injection into the TEXTOR tokamak in several material migration experiments. It is shown that Mo and W migrate in a similar way around the tokamak and that Mo can be used as tracer for W transport. It is further shown how other materials - medium-Z (Ni), low-Z (N-15 and F), fuel species (D) - migrate and get deposited. Finally, the outcome of dust sampling studies is discussed. It is shown that dust appearance and composition depends on origin, formation conditions and that it can originate even from remote systems like the NBI system. Furthermore, metal splashes and droplets have been found, some of them clearly indicating boiling processes. / <p>QC 20151203</p>

Aborder le roman féminin sous l‟angle d‟un énoncé discursif nécessite raisonnablement que l‟on prenne en compte, le contexte social, culturel et linguistique de production, les stratégies d‟énonciation, le champ de signification et les instances réceptrices qui déterminent ce discours. L‟approche sociopragmatique nous autorise pour ce faire à cette lecture plurielle qui, selon nous, mène incontestablement à une lisibilité optimale des textes. D‟abord, en tant que communication, le roman féminin implique des techniques discursives basées sur un environnement culturel et linguistique qui influence incontestablement le fonctionnement des énoncés en ce qui concerne les activités de production. Ensuite, la particularité des discours que nous étudions c‟est leur langage multiforme fait de paroles, d‟actes à valeur énonciatives, et d‟autres types de manifestations communicatives. C‟est un langage allégorique par essence, fait de sous-entendus, de diverses tournures imagées et aussi de silences parlants qui permettent d‟exprimer sans vraiment dire. Cette mise en scène théâtralisée du discours confère à l‟expression romanesque féminine un statut artistique particulier où la langue s‟enrichit d‟« accessoires linguistiques » d‟origine ethnique, régionale ou nationale. Enfin, la réception elle-même est fonction d‟un ensemble d‟éléments nécessaires à sa réalisation à savoir un espace, un temps, une orientation de réception intentionnellement glissée par l‟auteur. Ces éléments mis ensemble correspondent à ce que Kleiber nomme la "mémoire discursive" de l‟énonciateur et les "savoirs partagés" entre l‟émetteur et le récepteur / Going into feminine novel in a discursive statement approach, it is necessary to consider the social, linguistic and cultural contexts of the production. The enouncing strategies, the meaning field and the rulling receiving that determine the speech, are also to be taken in account. The socio pragmatic approach allows us thus to the plural reading we consider to lead indisputably to an optimal legibility of the texts. Firstly, as communication, the feminine novel involves discursive techniques based on both cultural and linguistic contexts influencing incontestably the functioning of utterances concerning production activities. Then, the particularity of the speeches under our study is their multiform language made on lyrics, acts with enunciative values, and other sort of communicative expressions. It is essentially an allegorical language, with hidden meanings, different imagery turns and talking silences that allows expression without actually saying. This theatralized staging of the speech confers on the feminine roman expression a peculiar artistic status where the language enriches of "linguistic accessories" from national and ethnic origins. Finally, the reception itself is a function of a whole of elements required to its carrying out namely, defined space, defined time, and an orientation of reception intentionally glide by the author. These elements put together correspond to what Kleber calls the "discursive memory" of the "enunciator" and the" shared knowledges" between the issuer and the receiver

O projeto de pesquisa propôs avaliar a metodologia de Simulação de Escalas Adaptativas (SAS) para descrever escoamentos turbulentos e não-reativos utilizando estudos de casos característicos, amplamente documentados, os quais possuem comportamentos do escoamento distintos presentes em diferentes regiões de uma câmara de combustão. O primeiro estudo de caso foi a análise do escoamento sobre um degrau, em que foi avaliada a capacidade do modelo Simulação de Escalas Adaptativas, frente aos modelos de Navier-Stokes com Média de Reynolds (RANS) e Simulação de Grandes Escalas (LES) e aos dados experimentais, em prever a distribuição de pressão, ponto de recolamento e de perfis de velocidade ao longo do domínio após a separação. Pode-se notar que o modelo SAS apresentou resultados praticamente idênticos aos resultados obtidos pelo modelo RANS com relação à distribuição de pressão e a posição ponto de recolamento. Porém, os perfis de velocidade apresentaram algumas discrepâncias com relação aos perfis de velocidade dos modelos RANS e LES e dos resultados experimentais. Um segundo estudo de caso foi a análise do escoamento através de um turbilhonador, em que a capacidade do modelo SAS foi avaliada, comparando seus resultados com os resultados do modelo de Navier-Stokes Não-Estacionárias com Média de Reynolds (URANS) e com os dados experimentais, em prever perfis de velocidade em regiões de recirculação presentes neste estudo de caso. Pode-se observar que ambos os modelos conseguiram prever as principais estruturas de recirculação do escoamento, porém, os perfis de velocidade apresentaram significativas discrepâncias com relação aos dados experimentais. Em seguida, foram feitas comparações entre os modelos SAS e URANS com relação à previsão da precessão central de vórtice e de estruturas de vórtices, das quais foi observado que o modelo SAS apresenta uma maior capacidade para prever estas estruturas em relação ao modelo URANS. / The research project aimed to evaluate the Scale-Adaptive Simulation (SAS) methodology to describe turbulent and non-reactive flows using characteristic, widely documented, case studies, which have distinct flow behaviors present in different regions of a chamber of combustion. The first case study was the analysis of a flow over a backward-facing step, from which the Scale-Adaptive Simulation (SAS) model capacity was evaluated, compared to the Reynolds Averaged Navier-Stokes (RANS) and Large-Eddy Simulation (LES) models and experimental data, in order to predict the pressure distribution, reattachment point and velocity profiles throughout the domain after separation. It can be noticed that the SAS model presented results almost identical to the results obtained by the RANS model in relation to the pressure distribution and reattachment position. However, the velocity profiles presented some discrepancies in respect to RANS and LES velocity profiles and the experimental results. A second case study was the analysis of the flow through a swirler, from which the capacity of the SAS model was evaluated, comparing its results to the results of the Unsteady Reynolds Averaged Navier-Stokes (URANS) model and with the experimental data, to predict velocity profiles in recirculation regions present in this case study. It can be observed that both models were able to predict the main recirculation structures of the flow, however, the velocity profiles presented significant discrepancies in relation to the experimental data. Then, comparisons were made between the SAS and URANS models in respect to the prediction of vortex precession vortex core and vortex structures, from which it was observed that the SAS model presents a greater capacity to predict these structures in relation to the URANS model.

Made available in DSpace on 2016-04-27T16:57:23Z (GMT). No. of bitstreams: 1 Natalia Coelho Soares.pdf: 1911222 bytes, checksum: 49a1ece22c9ff2a82a16d9ff71201d25 (MD5) Previous issue date: 2012-12-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research aimed to investigate whether and how eighth-grade middle school students who have difficulty in solving mathematical operations with natural numbers deepen their knowledge in this field when they have the opportunity to work with technological tools that are not frequently used in classroom. Data collection was based on twelve semi-structured interviews, which were done according to André (2008) concept of study of case. The students conceptions about solving mathematical operations with natural numbers were analyzed based mainly on the APOS theory. It was concluded that by introducing technological tools that are not frequently used in classroom, such as abacus and printing calculator, the students were allowed to deepen their knowledge about natural numbers and, consequently, reframe their conceptions about it / Este trabalho apresenta uma pesquisa de mestrado que teve o objetivo de investigar se e como, alunos do 8º ano do ensino fundamental, que apresentam dificuldades na resolução de atividades matemáticas que envolvem operações com os números naturais, aprofundam seus conhecimentos, quando lhes é dada a oportunidade do uso de tecnologias não usuais em sala de aula. Para a coleta de dados, foram realizadas doze entrevistas semiestruturadas que caracterizaram o estudo de caso, conforme definido por André (2008). As análises das concepções construídas pelos sujeitos basearam-se sobretudo na teoria APOS. Concluiu-se que a introdução das tecnologias não usuais, como o ábaco e, principalmente, a calculadora com impressora possibilitaram o aprofundamento e a consequente ressignificação das concepções dos sujeitos sobre as operações dos números naturais

Les sols forestiers contiennent des stocks de C importants et la gestion de tels espaces naturels est donc cruciale dans le contexte du changement climatique. Ce travail s’attache à comprendre quels leviers (facteurs environnementaux, pratiques sylvicoles) contrôlent le fonctionnement microbien des sols de peuplements représentatifs de Provence calcaire en considérant différentes échelles spatiales. La hiérarchisation des facteurs modulant le fonctionnement des sols forestiers a mis en évidence une structuration des communautés fonctionnelles microbiennes à l’échelle régionale par les conditions bioclimatiques (bioclimats sub-humide vs. humide), et une modulation des activités enzymatiques à l’échelle locale par la MO définie par le peuplement (Quercus ilex et Pinus halepensis vs. Q. pubescens et P. sylvestris en composition pure ou mixte). Les effets de la mixité forestière (décrite via les surfaces terrières et les densités des troncs) sur le fonctionnement du sol a été évaluée dans les deux contextes bioclimatiques: la complémentarité des essences en peuplements mixtes sous bioclimat humide favorise le recyclage de la MO et induit une diminution des stocks de C et N, cet effet non-additif des essences n’est pas observé sous bioclimat sub-humide. L’addition de différents types de rémanents (feuilles/aiguilles vs. bois) a été testée en mésocosmes : les équilibres entre les populations fongiques et bactériennes sont conditionnés par le ratio C/N, lui-même dépendant du type de rémanents apporté. Ainsi, ces résultats indiquent que les pratiques sylvicoles pourraient orienter les dynamiques des flux de C dans les sols forestiers. / Since forest soils can store large carbon amounts, the management of such ecosystem is of major importance considering the forecasted climate change. This work aims at understanding which drivers (environmental factors and sylvicultural practices) control soil microbial functioning in forest stands of Provence (South of France) considering different spatial scales. The hierarchization of drivers showed that microbial functional diversity is driven at the regional scale by bioclimatic conditions (sub-humid vs. humid bioclimate) and enzyme activities at the local scale by the organic matter print defined by stand composition (Quercus ilex and Pinus halepensis vs. Q. pubescens and P. sylvestris in pure or mixed stand). Mixed forest composition and structure (described through basal area and density of trunks of pines and oaks) influenced soil functioning differently depending on the bioclimate: the complementarity of species in mixed stands in humid bioclimate favoured organic matter recycling and induced a decrease in C and N stocks, while an additive effect of tree species was found in sub-humid bioclimate. Amendments with different types of logging residues (leaves / needles vs. wood) were tested in mesocosms: the balance between fungal and bacterial populations was conditioned by the C to N ratio, C and N amounts varying with the type of residue. Thus, these results indicate that forest management - through the choice of adapted practices - has the potential to drive microbial functioning in forest soils.

Metal surface cleaning is highly required in different fields of modern industry. Nuclear industry seeks for new methods for oxidized surface decontamination, and thermonuclear installations require the cleaning of plasma facing components from tritium-containing deposited layer. The laser ablation is proposed as an effective and safe method for metal surface cleaning and decontamination. The important factor influencing the laser heating and ablation is the in-depth distribution of laser radiation. The model of light propagation in a scattering layer on a metal substrate is developed and applied to analyse the features of light distribution. To simulate the contaminated surfaces, the stainless steel AISI 304L was oxidized by laser and in a furnace. Radioactive contamination of the oxide layer was simulated by introducing europium and/or sodium. The decontamination factor of more than 300 was demonstrated with found optimal cleaning regime. The decreasing of the corrosion resistance was found after laser cleaning. The ablation thresholds of ITER-like surfaces were measured. The cleaning productivity of 0.07 m2/hour∙W was found. For mirror surfaces, the damage thresholds were determined to avoid damage during laser cleaning. The possibility to restore reflectivity after thin carbon layer deposition was demonstrated. The perspectives of further development of laser cleaning are discussed.

The research in permanent magnet thin films focuses on the search of new materials and methods to increase the prevalent data storage limit. In the recent past the work towards the application of these films to micro systems have also gained momentum. Materials like samarium cobalt with better magnetic properties and temperature stability are considered to be suitable in this regard. The essential requirement in miniaturization of these films is to deposit them on silicon substrates that can alleviate the micro fabrication process. In this work, an effort has been made to deposit SmCo films with better magnetic properties on silicon substrates. In the deposition of SmCo, the composition of the deposited films and the structural evolution are found to play an important role in determining the magnetic properties. Proper control over these parameters is essential in controlling the magnetic properties of the deposited films. SmCo being a two component material the composition of the films is dependent on the nature of the source and the transport of the material species from source to substrate. On the other hand, structural evolution is dependent on the energetical considerations between the SmCo lattice and substrate lattice. This most often is dominated by the lattice match between the condensing lattice and the substrate lattice. As such Si does not provide good lattice match to SmCo lattice. Hence suitable underlayers are essential in the deposition of these films. Materials like W, Cu, Mo and Cr were used as underlayers. Out of all these Cr is found to provide good lattice match and adhesion to SmCo lattice. Sputtering being the common deposition tool, SmCo could be sputtered either from the elemental targets of Sm and Co or from the compound target of SmCo5. Sputtering of elemental targets of Sm and Co provides the flexibility of varying the composition whereas sputtering from the SmCo alloy target provides to flexibility of controlling the structural evolution by different process parameters. In this work two different techniques namely Facing Target Sputtering (FTS) and Ion Beam Sputter Deposition (IBSD) were followed in depositing SmCo films. In FTS technique, SmCo films were directly deposited on silicon substrates by simultaneous sputtering of samarium and cobalt targets facing each other. This sputtering geometry enabled to achieve films with a wide composition range of 55 – 95 at. % of cobalt in single deposition. The resulting composition variation and material property variation were investigated in terms of process parameters like pressure, temperature, SubstrateTarget Distance (STD) and InterTarget Distance (ITD). The composition distribution of the films was found to be dependent on the thermalisation distances and the mean free path available during the transport. To explain the process and the composition variation, a simulation model based on Monte Carlo method has been employed. The simulated composition variation trends were in good agreement with that of the experimental observations. IBSD, known for its controlled deposition, was employed to deposit both Cr (as an underlayer) and SmCo films. Cr with close epitaxial match with SmCo induces structural evolution in deposited films. The initial growth conditions were found to play a dominant role in the structural evolution of these Cr films. Hence, initial growth conditions were modified by means of oblique incidence and preferential orientation of (200) plane was obtained. With three different angles of incidence, three different surface orientations of Cr films were achieved. These films were then used as structural templates in the deposition of SmCo films. The influence of parameters like composition, impurities, film thickness, beam energy, ion flux, annealing, angles of incidence and underlayer properties on the structural and magnetic properties of SmCo was studied. The structural evolution of SmCo has been found to depend on the structural orientation of Cr underlayers. This followed the structural relation of SmCo(100)||Cr(110)||Si(100) and SmCo(110)||Cr(100)||Si(100). A mixed surface plane orientation was observed in the case of mixed orientation Cr template. The magnetic coercivities were found to increase from 50 Oe to 5000 Oe with the change in the structure of the deposited films.

The course of endstage renal disease (ESRD) and receiving hemodialysis (HD) treatment is complex and filled with uncertainty. Part of this illness experience includes making end-of-life (EOL) care decisions. Many families are unprepared to make such decisions. Advance care planning (ACP) creates an excellent context for laying the groundwork for these emotionally charged conversations. Hemodialysis patients, their families and healthcare providers (HCPs) are in a unique position to begin the ACP process early in the illness trajectory, revisiting it when the patient’s health status, prognosis and treatment modality changes. To date, little research has focused directly on how families experience ACP conversations in the context of ESRD or HD. The purpose of this study was to explore family members’ experiences of participating in a facilitated ACP conversation with the HD patient. This approach recognizes and privileges the family’s role in the illness trajectory of ESRD and validates that they too are HCPs’ clients. Five families, consisting of the HD patient and one family member, who went through the ACP process were interviewed along with an ACP facilitator from the nephrology program. This focused ethnographic study applied the theoretical perspective of postmodernist critical theory to derive and analyze data from in-depth semi-structured interviews. Findings revealed a detailed description of the ACP process that included timing, readiness to acknowledge the potentiality of death, facing mortality, and finding meaning in the illness experience. As families started to deconstruct their experiences, they shared stories of communication breakdown, highlighting the complexities of their relationships with HCPs. Understanding the factors that potentially contribute to HD patients’, their families’ and the renal staff’s discomfort with death were analyzed. The study findings provide important direction for HCPs about how families make ACP decisions, how they perceive the ACP process, and what they identify as their EOL care needs and wishes. Failure to implement ACP as part of an EOL care program means that death will continue to be denied and clients’ EOL care needs will remain un-addressed. In order for ACP to be effective on HD units, sustainable resources are essential for patients, their families and HCPs.

The course of endstage renal disease (ESRD) and receiving hemodialysis (HD) treatment is complex and filled with uncertainty. Part of this illness experience includes making end-of-life (EOL) care decisions. Many families are unprepared to make such decisions. Advance care planning (ACP) creates an excellent context for laying the groundwork for these emotionally charged conversations. Hemodialysis patients, their families and healthcare providers (HCPs) are in a unique position to begin the ACP process early in the illness trajectory, revisiting it when the patient’s health status, prognosis and treatment modality changes. To date, little research has focused directly on how families experience ACP conversations in the context of ESRD or HD. The purpose of this study was to explore family members’ experiences of participating in a facilitated ACP conversation with the HD patient. This approach recognizes and privileges the family’s role in the illness trajectory of ESRD and validates that they too are HCPs’ clients. Five families, consisting of the HD patient and one family member, who went through the ACP process were interviewed along with an ACP facilitator from the nephrology program. This focused ethnographic study applied the theoretical perspective of postmodernist critical theory to derive and analyze data from in-depth semi-structured interviews. Findings revealed a detailed description of the ACP process that included timing, readiness to acknowledge the potentiality of death, facing mortality, and finding meaning in the illness experience. As families started to deconstruct their experiences, they shared stories of communication breakdown, highlighting the complexities of their relationships with HCPs. Understanding the factors that potentially contribute to HD patients’, their families’ and the renal staff’s discomfort with death were analyzed. The study findings provide important direction for HCPs about how families make ACP decisions, how they perceive the ACP process, and what they identify as their EOL care needs and wishes. Failure to implement ACP as part of an EOL care program means that death will continue to be denied and clients’ EOL care needs will remain un-addressed. In order for ACP to be effective on HD units, sustainable resources are essential for patients, their families and HCPs.

Divertors are in-vessel, plasma-facing, components in magnetic-confinement fusion reactors. Their main function is to remove the fusion reaction ash (α-particles), unburned fuel, and eroded particles from the reactor, which adversely affect the quality of the plasma. A significant fraction (~15 %) of the total fusion thermal power is removed by the divertor coolant and must, therefore, be recovered at elevated temperature in order to enhance the overall thermal efficiency. Helium is the leading coolant because of its high thermal conductivity, material compatibility, and suitability as a working fluid for power conversion systems using a closed high temperature Brayton cycle. Peak surface heat fluxes on the order of 10 MW/m^2 are anticipated with surface temperatures in the region of 1,200°C to 1,500°C. Recently, several helium-cooled divertor designs have been proposed, including a modular T-tube design and a modular finger configuration with jet impingement cooling from perforated end caps. Design calculations performed using the FLUENT® CFD software package have shown that these designs can accommodate a peak heat load of 10 MW/m^2. Extremely high heat transfer coefficients (~50,000 W/(m^2 K)) were predicted by these calculations. Since these values of heat transfer coefficient are considered to be outside of the experience base for gas-cooled systems, an experimental investigation has been undertaken to validate the results of the numerical simulations. Attention has been focused on the thermal performance of the T-tube and the finger divertor designs. Experimental and numerical investigations have been performed to support both divertor geometries. Excellent agreement has been obtained between the experimental data and model predictions, thereby confirming the predicted performance of the leading helium-cooled divertor designs for near- and long-term magnetic fusion reactor designs. The results of this investigation provide confidence in the ability of state-of-the-art CFD codes to model gas-cooled high heat flux plasma-facing components such as divertors.