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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

Sondová diagnostika nízkoteplotního plazmatu při depozičním procesu

KOZLOVÁ, Miroslava January 2017 (has links)
This master thesis deals with examination of the parameters of low temperature plasma which is used for the deposition of thin layer of ITO. The method which is used in this thesis is the probe diagnostics. This thesis is divided into two parts. The first is the theoretical part, in which the basic parameters of low temperature plasma, principles of the probe diagnostics, and theories for this method are explained. The second part is the practical part, which presents the results of the measurement depending on changes in conditions of deposition.
252

Formation de silicium poreux appliquée à la réalisation de caissons isolants dans le silicium / Porous silicon formation applied to insulating boxes realized into silicon

Semai, Jugurtha 20 December 2010 (has links)
Le développement du marché des appareils de communication nomades, a nécessité l'intégration de composants passifs et actifs sur du silicium via des montages « hybrides ».Ceci a amené le LMP partenaire de l'entreprise STMicroelectronics à rechercher des solutions pour une intégration « monolithique ». Le silicium micro/mésoporeux est un candidat potentiel pour satisfaire les exigences de cette intégration. Ce travail traite de la réalisation de caissons profonds de silicium poreux sur silicium résistif de type P 30-50 Ω.cm et N 37-46Ω.cm. L'utilisation de l'acide acétique comme solvant industriellement compatible nous a permis de réaliser des structures micro/mésoporeuses. L'intégrité mécanique de nos échantillons a été étudiée via la mesure de la porosité en fonction de l'épaisseur. Ainsi des caissons poreux avec des épaisseurs de plus de 400 µm et 50 % de porosité ont été fabriqués.La réalisation d'une couche N⁺ sur du silicium type N 37-46 Ω.cm a permis la mise en œuvre de doubles couches composées d'une dizaine de micromètres de micro/mésoporeuse sur une couche de 200 µ.m de silicium macroporeux. Des changements importants ont été observés par addition d'une très faible quantité d'un tensioactif (triton X-I00®) a notre solution électrolytique et où des doubles couches ont été obtenues sur silicium type P 30-50 Ω.cm. / The rapid expansion of wireless devices caused a tremendous demand of the development of active and passive devices integration on silicon via « hybrid » systems. The search of a« monolithic » integration has led the LMP in partnership with STMicroelectronics to focus on this topic. Micro/Mesoporous silicon is a good candidate to fulfill the requirements to achieve this purpose. The present work deals with the realization of thick porous silicon layers on low doped P type (30-50 Ω.cm) and N type Si (37-46 Ω.cm). The use of a particular solution based on HF-H₂O and acetic acid allowed the implementation of micro/mesoporous Si structures. The mechanical integrity is studied via the porosity and the PS layer thickness.Thus layers with a thickness up to 400 µm have been implemented with a porosity of 50 % on P Type Si samples. Double layers with micro/mesoporous layer of tenth micrometers on a macroporous layer stack up to 200 µm have been realized on N-Type Si samples via the realization of an N⁺ layer by phosphorous implantation. Important changes occurred when a tiny amount of surfactant (triton X-I00®) has been introduced into our organic electrolyte and allowed the implementation of double layers on P type Si.
253

Low Temperature Electrical Transport in 2D Layers of Graphene, Graphitic Carbon Nitride, Graphene Oxide and Boron-Nitrogen-Carbon

Muchharla, Baleeswaraiah 01 December 2015 (has links)
In this work, we have investigated temperature dependent electrical transport properties of carbon based two-dimensional (2D) nanomaterials. Various techniques were employed to synthesize the samples. For instance, high quality large area graphene and boron, nitrogen doped graphene (BNC) were grown using thermal catalytic chemical vapor deposition (CVD) method. Liquid phase exfoliation technique was utilized to exfoliate graphene and graphitic carbon nitride samples in isopropyl alcohol. Chemical reduction technique was used to reduce graphene oxide (rGO) by utilizing ascorbic acid (a green chemical) as a reducing agent. Detailed structural and morphology characterization of these samples was performed using state of the art microscopy as well as spectroscopic techniques (for example; Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), UV-Visible spectroscopy as well as Raman Spectroscopy). The low temperature (5 K< T <400 K) electrical transport properties of these materials show substantial difference from sample to sample studied. For instance, CVD grown graphene film has displayed metallic behavior over a wide range of temperature (5 K < T <300 K). At higher temperatures, resistivity followed linearly with the temperature (ρ(T) ~T). A power law dependence (ρ(T) ~ T4) observed at lower temperatures. Where as liquid phase exfoliated graphene and graphitic carbon nitride samples displayed nonmetallic nature: increasing resistance with decrease in temperature over a wide range (8 K < T < 270 K) of temperature. Electrical transport behavior in these samples was governed by two different Arrhenius behaviors in the studied temperature range. In the case of rGO and BNC layers, electrical conduction show two different transport mechanisms in two different temperature regimes. At higher temperatures, Arrhenius-like temperature dependence of resistance was observed indicating a band gap dominating transport behavior. At lower temperatures, Mott's two dimensional-Variable Range Hopping (2D-VRH) behavior was observed.
254

The importance of elemental stacking order and layer thickness in controlling the formation kinetics of copper indium diselenide

Thompson, John O., 1962- 12 1900 (has links)
xiii, 84 p. ; ill. / This dissertation describes the deposition and characterization of an amorphous thin film with a composition near that of CuInSe 2 (CIS). The creation of an amorphous intermediate leads to a crystalline film at low annealing temperatures. Thin films were deposited from elemental sources in a custom built high vacuum chamber. Copper-selenium and indium-selenium binary layered samples were investigated to identify interfacial reactions that would form undesired binary intermediate compounds resulting in the need for high temperature annealing. Although the indium-selenium system did not form interfacial compounds on deposit, indium crystallized when the indium layer thickness exceeded 15 angstroms, disrupting the continuity of the elemental layers. Copper-selenium elemental layers with a repeat thickness of over 30 angstroms or compositions with less than 63% selenium formed CuSe on deposit. Several deposition schemes were investigated to identify the proper deposition pattern and thicknesses to form the CIS amorphous film. Simple co-deposition resulted in the nucleation of CIS. A simple stacking of the three elements in the older Se-In-Cu at a repeat thickness of 60 angstroms resulted in the nucleation of CuSe and sometimes CIS. The CIS most likely formed due to the disruption of the elemental layers by the growth of the CuSe. Reduction of the repeat thickness to 20 angstroms eliminated the nucleation of CuSe, as predicted by the study of the binary Cu-Se layered samples, but resulted in the nucleation of CIS, similar to the co-deposited samples. To eliminate both the thick Cu-Se region, and prevent the intermixing of all three elements, a more complex deposition pattern was initiated. The copper and selenium repeat thicknesses were reduced into a Se-Cu-Se-Cu-Se pattern followed by deposition of the indium layer at a total repeat thickness of 60 angstroms. At a Se:Cu ratio of 2:1 and the small repeat thickness, no Cu-Se phases nucleated. Additionally, the Cu-In interface was eliminated. For this deposition scheme, films with a selenium rich composition relative to CuInSez were generally amorphous. Those that were Cu-In rich always nucleated CIS on deposit. Annealing of all samples produced crystalline CIS. / Adviser: David C. Johnson
255

Evaluating the effective oxygen diffusion coefficient in blends of till and green liquor dregs (GLD) used as sealing layer in mine waste covers

Virolainen, Anna January 2018 (has links)
Dry covers can be used to limit the generation of acid mine drainage from sulphidic mine waste exposed to air and water. For the covers to act efficiently a high degree of saturation should be maintained in the cover, as the diffusion of oxygen is substantially reduced in water compared to that in air. Historically, dry covers made solely from till have been applied with varying degrees of success. To improve the performance of dry covers, a multi-layer approach can be applied incorporating a sealing layer aimed at effectively preventing oxygen ingress and an overlying protective layer. Blends of till and green liquor dregs (GLD) are thought to have advantageous properties regarding the water retention capacity and hydraulic conductivity. Subsequently, the blends should have a good ability to remain highly saturated during dry periods and be able to maintain their function as oxygen diffusion barriers over time. In this study the effective oxygen diffusion coefficient (De) in blends of till and GLD was evaluated by laboratory measurements. The oxygen diffusion coefficient of till-GLD blends was evaluated through 81 diffusion tests performed at different degrees of water saturation. The blends differed in added amounts of GLD and different types of GLD. These variables were studied as they affect the blends grain size, porosity, tortuosity, and degree of saturation, which in turn affect the De. The tests were performed in two-chamber diffusion cells and interpreted using the software Vadose/W (Geoslope, 2016) to determine the De. The results provide an initial evaluation of the variation of De that can be expected for till-GLD blends. The De was found to vary greatly for the blends (10-6 &gt; De &gt; 10-11 m2 s-1) depending on the degree of saturation. Even though the GLD contain substantial amounts of water, a high water content of the till was still required to reach a low De. A predictive model for estimating the De based on basic geotechnical soil properties was compared to the De from the interpreted diffusion tests. The model could generally predict the De to within an acceptable range (± one order of magnitude). Additionally, diffusion tests performed on materials dried in successive steps showed how the De changed over time when exposed to drying. A sharp increase in the De was found for the blends, pure GLD and pure till when exposed to drying. Thus, no clear improvement was found for the GLD-till blends compared to the pure till. These results indicate that the till-GLD layers should not be exposed to drying as loss of cover efficiency may occur. This can have implications for the use of till-GLD blends as sealing layers in terms of the design of the protective cover and the placement of covers. To validate these results, tests on larger material quantities should be performed, preferably in field conditions, and comparison to field measurements would be of high interest.
256

Characterisation of intermixed quantum well material by measurements of spontaneous emission

Blay, Claire January 2000 (has links)
No description available.
257

Réflectivité magnétique résonante de rayons X mous : une sonde de la distribution d'aimantation complexe au sein de films minces / Soft X-ray Resonant Magnetic Reflectivity : a probe for complex magnetization distribution in thin films

Jal, Emmanuelle 26 September 2013 (has links)
Cette thèse traite de l'étude de films ultra minces de Fe par réflectivité magnétique résonante de rayons X mous (SXRMR). La technique de SXRMR associe les effets magnéto-optiques aux propriétés de diffusions des rayons X, ce qui permet sonder les propriétés magnétiques avec une résolution spatiale en profondeur. Un profil magnétique résolu en profondeur est donc dérivé des expériences, permettant d'étudier les effets des interfaces sur l'homogénéité des propriétés magnétiques. Dans un premier temps nous présentons l'étude d'un film mince de Fe sur un substrat vicinal d'Ag(116) recouvert par quinze monocouches d'Au. Cette étude révèle que l'aimantation est augmentée de 20 à 30$\%$ dans les deux à trois monocouches proches des interfaces d'Au et d'Ag, quelque soit la température et l'épaisseur de la couche de Fe. Nous avons également mis en évidence une inhomogénéité de la composante hors du plan à basse température pour des échantillons ayant un axe de facile perpendiculaire aux marches : la composante de l'aimantation hors du plan est de plus en plus grande lorsqu'on se rapproche du substrat vicinal d'Ag. Dans un deuxième temps, nous présentons l'étude d'un film mince de six monocouches de Fe sur du Cu(100) et recouvert par une couche d'Au. En utilisant une approche originale de contrainte sur les paramètres magnétiques, nous avons pû mettre en évidence que la dépendance de l'aimantation en fonction de la température n'était pas la même selon la position de la monocouches dans le film mince de Fe, comme prédit théoriquement par Sandratski. / This thesis deals about depth resolved magnetic profile of ultrathin Fe layers studied by soft X-ray Resonant Magnetic Reflectivity (SXRMR). This SXRMR technique combines magneto-optic effects to X-ray scattering allowing to be sensitive to magnetic properties as well as to be depth resolved. For each experiments, the depth resolved magnetic profile found allows to study interfaces effect on the homogeneity of magnetic properties. First, we present the study of a thin film of Fe grown on a vicinal substrate of Ag(116) and covered by fifteen monolayers of Au. This study reveal that the magnetization is enhanced of 20 to 30$\%$ int the two to three monolayers near both interfaces, whatever the temperature and the Fe thickness are. We have also discover an inhomogeneity of the magnetic out of plane component at low temperature for sample where the magnetization easy axis is perpendicular to the steps : the magnetic out of plane component is more and more important when we go strait to the vicinal substrate of Ag. Second, we show the study of a thin film of six monolayers of Fe grown on a Cu(100) substrate and covered by a Au layer. Using a new way of strain on magnetic parameter we have highlighted that the temperature dependance of the magnetization is not the same depending ont the position of the monolayer inside the Fe thin film as predicted by the theory of Sandratski.
258

Modelos de dimensão finita e infinita para avaliação da produção de ovos em aves de postura /

Venturini, Guilherme Costa. January 2009 (has links)
Resumo: Objetivou-se estimar parâmetros genéticos e fenotípicos da produção de ovos total e parcial em aves de postura por meio de modelos de dimensão finita e infinita, visando à seleção das aves para a característica produção de ovos. Utilizou-se dados de fêmeas, nascidas a partir de três incubações, provenientes de uma geração de uma linhagem de poedeiras, desenvolvida pela EMBRAPA Suínos e Aves em Concórdia, SC. A produção de ovos foi avaliada individualmente por meio do número de ovos, a partir de 20 até 70 semanas de idade. As produções foram divididas em períodos, sendo que cada período consistiu em três semanas de produção. As características estudadas foram os registros parciais nos períodos e o registro total da produção de ovos (PTOTAL). Para análise em modelo animal uni e bicaracterística, utilizou-se o programa computacional MTDFREML. Maior herdabilidade foi estimada para o período de 20 a 22 semanas de idade (P1) e PTOTAL (0,33 ± 0,07 e 0,23 ± 0,06). Correlações genéticas entre os períodos parciais e PTOTAL variaram de 0,42 ± 0,15 (PTOTAL com P2, de 20 a 22 semanas de idade) até 1,00 (PTOTAL com P9 e P11, de 44 a 46 e 50 a 52 semanas de idade, respectivamente). A correlação de Spearman entre as ordens dos 43 galos quanto aos valores genéticos para produção de P9, P10 (de 47 a 49 semanas de idade) e de P11 com PTOTAL foi significativa (p<0,001) para P9 e P11, igual a 1,00 e para P10 (p<0,0028), igual a 0,99. Concluiu-se que o registro parcial de ovos para os períodos P9, P10 e P11 poderiam ser considerados no processo de seleção visando à produção total de ovos. Porém, devido os mesmos apresentarem baixas estimativas de herdabilidade (0,06; 0,12 e 0,10, respectivamente para P9, P10 e P11) a seleção seria mais eficiente considerando o PTOTAL. Portanto, seria recomendada a seleção baseada na produção total de ovos, pois a mesma... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim was to estimate genetic and phenotypic parameters for total and partial records of egg production of laying hens using finite and infinite-dimension models, with a view to selecting birds for egg production. Data on females born from three incubations, from a generation of an egg-laying strain developed by EMBRAPA Suínos e Aves, Concórdia, SC, were used. Egg production was evaluated individually as the number of eggs produced between the ages of 20 and 70 weeks. The production was divided into three-week periods. The traits studied were the partial records for each period (P1 to P17) and the total recorded egg production (PTOTAL). For analysis in one and two-trait animal models, the MTDFREML software was used. Higher heritabilities were estimated for the periods of 20 to 22 weeks of age (P1) (0.33 ± 0.07) and PTOTAL (0.23 ± 0.06). The genetic correlations between the partial periods and PTOTAL ranged from 0.42 ± 0.15 (P1) to 1.00 (for P9 and P11, representing 44-46 and 50-52 weeks of age, respectively). Spearman's correlation between the ranks of the 43 sires, regarding the genetic values for production in P9, P10 (47-49 weeks of age) and P11 in relation to PTOTAL, was significant and equal to 1.00 (P<0.001) for P9 and P11 and equal to 0.99 (P<0.0028) for P10. Although highly correlated with PTOTAL, these periods had low heritability estimates in two-trait analysis (0.06, 0.12 and 0.10, respectively for P9, P10 and P11). Thus, selection based on these partial periods would be inefficient and basing it on total egg production would be recommended, since this presented higher heritability estimates. To estimate the covariance functions using random regression models, the DXMRR option in the DFREML statistical software was used. The most appropriate model regarding goodness-of-fit of the egg production data in these laying hens was the one composed of third-order... (Complete abstract click electronic access below) / Orientador: Danísio Prado Munari / Coorientadora: Lenira El Faro Zadra / Coorientadora: Mônica Côrrea Ledur / Banca: João Ademir de Oliveira / Banca: Claudia Cristina Paro de Paz / Mestre
259

A theoretical study of the transference of heat and momentum across turbulent incompressible boundary layers

DIAZ DIEGUEZ, J.A. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:50:37Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:52Z (GMT). No. of bitstreams: 1 00621.pdf: 16649575 bytes, checksum: 34a61ca5ff67945244a79765b98ddb45 (MD5) / Tese (Doutoramento) / IEA/T / University of London
260

Influência da configuração de bobinagem no comportamento mecânico de cilindros de compósito polimérico

CARVALHO, OSNI de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:25:54Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:39Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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