Um dos desafios mais importantes para a indústria de bens eletrônicos de consumo é o desenvolvimento de um dispositivo mostrador de informação (display) que tenda aos requisitos de alta qualidade de imagem, grande área, baixo consumo de energia e baixo custo. O display de comissão de campo (field emission display, ou FED) representa a tecnologia com maior potencial para atender a estes requisitos. No entanto a baixa durabilidade e a baixa confiabilidade dos protótipos baseados em emissores metálicos impedem que esta tecnologia entre no mercado. Neste trabalho, investigam-se duas abordagens que podem representar urna solução para estas deficiências: a melhora do vácuo na câmara de emissão e o emprego de nanotubos de carbono como emissores. No que se refere a melhora das propriedades de vácuo num FED, este trabalho propõe um novo tipo de emissor baseado em uma membrana porosa. Cálculos teóricos referentes as propriedades de vácuo e ao fator de amplificação do campo eletrostático são apresentados para esta nova configuração, sendo proposto um modelo para determinar o limite superior do fator de amplificação do campo. No que se refere a parte experimental, e demonstrado que membranas porosas de diamante de fato funcionam como emissores, de acordo com a proposta. O desempenho destas membranas e comparado com o de condutores metálicos planos, com e sem um recobrimento de diamond-like carbon. São apresentadas imagens dos spots de emissão em poros, e um estudo da estabilidade de emissão de longo prazo e realizado. No que se refere aos nanotubos de carbono este trabalho propõe um novo processo de tratamento dos nanotubos em arco de plasma que resulta em melhora das propriedades de emissão destas estruturas. Um estudo da estabilidade de emissão dos nanotubos também e apresentado, sendo que uma degradação sistemática da emissão e relatada para o caso de nanotubos mono-parede (single-wall). / One of the most important challenges to the electronics industry is the production of a flat panel display which fulfills the requirements of high quality image, large area low power and low cost. Field Emission Display (FED) is the technology in best conditions to face these requirements. However, the short lifetime and low reliability of FED prototypes based on metallic emitters are hindering this technology to get into the market. In this work we investigate two different approaches that could represent a solution for these problems: improvement of the vacuum characteristics inside the emission chamber and use of carbon nanotubes as emitters. With respect to the improvement of vacuun in a FED, this work proposes a new type of emitter based on a porous diamond membrane. Theoretical calculations referent to the vacuum properties and referent to electrostatic field enhancement factor are presented. A new model is proposed to determine the superior limit for the eletrostatic field enhancement factor in a porous emitter. With respect to the experimental part of this work, we show that diamond porous membranes indeed emit electrons, according to the original proposition. The emission performance of these membranes is compared to the performance of flat metalic emitters, coated or Dot with diamond-like carbon. Images of emission spots in pores and a study of the long term membrane emission stability are presented. With respect to carbon nanotubes this work presents a. new treatment process, under plasma arc, that resulted in emission improvement. A study all emission stability of nanotubes is also presented, and systematical emission decay is reported for single-wall nanotubes.

本研究旨在探討國家圖書館數位保存計畫之促成因素與相關問題，藉由比較研究之描述、解釋、併排與比較四步驟，研究美國與澳洲國家圖書館數位保存計畫之內涵，瞭解美國國會圖書館與澳洲國家圖書館在數位保存活動中扮演的角色、任務、法定寄存制度、數位保存計畫背景與促成因素等，歸納數位保存策略與典範，以提出我國發展數位保存計畫之建議與參考。 研究結果歸納促成美國與澳洲國家圖書館數位保存計畫發展的15項共同因素與3項不同因素。共同因素為：1.兩國皆因著作權法促成國家圖書館擔負法定寄存的責任；2.重視數位保存問題；3.重視數位資源法定寄存；4.數位資源採自願寄存協議；5.落實國家數位保存計畫；6.落實網站典藏保存計畫；7.採合作蒐集數位資源的策略；8.研訂所需描述性後設資料標準；9.採用多種Metadata架構；10.研訂保存性後設資料標準；11.數位保存技術策略；12.採用唯一的數位保存官方標準OAIS參考模式；13.採用HTTrack網站擷取工具；14.重視數位資源的永久取用；15.合宜的數位資源取用策略。不同因素為：1.國家數位保存計畫發展方式不同；2.網路資源典藏計畫不同；3.數位資源選擇決策不同。 本論文結論歸納發展國家數位保存應考量下列議題：1.國家圖書館數位保存的重要性；2.法定寄存制度與數位資源寄存問題；3.數位保存計畫推動；4.數位資源館藏政策與選擇指南；5.網路資源編目標準；6.Metadata標準；7.描述性後設資料；8.保存性後設資料；9.數位典藏庫；10.數位保存策略；11.數位保存取用與服務；12.數位保存成功因素與策略。 最後建議：1.加強原生數位資料研究；2.國家圖書館推動我國數位保存計畫；3. 建置我國網站典藏先導計畫；4.訂定數位館藏發展政策；5.訂定數位保存政策。 / The purpose of the study is to analyze the factors that helped to materialize the national library digital preservation projects. Through description, interpretation, juxtaposition, and comparison, this study research the concepts of the digital preservation projects from Library of Congress and National Library of Australia, which include the role, the mission, the legal deposit policy, the background, and the relevant factors of the digital preservation standards and strategy. Finally come up with the suggestion of the digital preservation projects of our own. The results of this study include 15 common factors and 3 different factors. The common factors are: 1.The national libraries are responsible for the legal deposit policy due to the copyright act；2.Emphasize on the digital preservation；3. Emphasize on the legal deposit policy；4.There is no common agreement on digital resources deposit policy；5.Carry out national digital preservation projects；6.Execute the web capture projects；7.Adopt the strategy of collecting digital resources together； 8.Construct the descriptive metadata standards；9.Adopt several metadata schemas； 10.Construct preservation metadata standards；11.Digital preservation strategy；12. Adopt official digital preservation standard OAIS；13.Adopt HTTrack web capture tool；14.Emphasize on the permanent access of the digital resources；15.Appropriate digital resources access strategy. The different factors are: 1.The development of the national digital preservation projects；2.The collection of the web-based resources projects；3.The selection decision of the digital resources. The conclusions of the study are: 1.The importance on digital preservation of a national library；2.The issues of legal deposit policy and the deposition of the digital resources；3.Successfully promote the development of a digital preservation project；4.Digital resources collection policy and selection guidelines；5.Web resources cataloging standards；6.Metadata standards；7.Descriptive metadata；8.Preservation metadata；9.Digital repository；10.Digital preservation strategy；11.Access and services of digital preservation；12.Succesful factors of promoting digital preservation projects. The study makes final suggestions as follows: 1.Emphasis on the research of born digital materials. 2. Promote national central library to develop our national digital preservation projects. 3. Construct the web-archiving pilot project. 4. Establish the digital collection development policy. 5. Establish the digital preservation policy.

Made available in DSpace on 2014-12-17T14:07:01Z (GMT). No. of bitstreams: 1 NataliaFD_DISSERT.pdf: 4136751 bytes, checksum: 47b384d6442f251d58542735c23ae300 (MD5) Previous issue date: 2012-02-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Titanium nitride films were grown on glass using the Cathodic Cage Plasma Deposition technique in order to verify the influence of process parameters in optical and structural properties of the films. The plasma atmosphere used was a mixture of Ar, N2 and H2, setting the Ar and N2 gas flows at 4 and 3 sccm, respectively and H2 gas flow varied from 0, 1 to 2 sccm. The deposition process was monitored by Optical Emission Spectroscopy (OES) to investigate the influence of the active species in plasma. It was observed that increasing the H2 gas flow into the plasma the luminescent intensities associated to the species changed. In this case, the luminescence of N2 (391,4nm) species was not proportional to the increasing of the H2 gas into the reactor. Other parameters investigated were diameter and number of holes in the cage. The analysis by Grazing Incidence X-Ray Diffraction (GIXRD) confirmed that the obtained films are composed by TiN and they may have variations in the nitrogen amount into the crystal and in the crystallite size. The optical microscopy images provided information about the homogeneity of the films. The atomic force microscopy (AFM) results revealed some microstructural characteristics and surface roughness. The thickness was measured by ellipsometry. The optical properties such as transmittance and reflectance (they were measured by spectrophotometry) are very sensitive to changes in the crystal lattice of the material, chemical composition and film thicknesses. Therefore, such properties are appropriate tools for verification of this process control. In general, films obtained at 0 sccm of H2 gas flow present a higher transmittance. It can be attributed to the smaller crystalline size due to a higher amount of nitrogen in the TiN lattice. The films obtained at 1 and 2 sccm of H2 gas flow have a golden appearance and XRD pattern showed peaks characteristics of TiN with higher intensity and smaller FWHM (Full Width at Half Maximum) parameter. It suggests that the hydrogen presence in the plasma makes the films more stoichiometric and becomes it more crystalline. It was observed that with higher number of holes in the lid of the cage, close to the region between the lid and the sample and the smaller diameter of the hole, the deposited film is thicker, which is justified by the most probability of plasma species reach effectively the sample and it promotes the growth of the film / Filmes finos de nitreto de tit?nio foram crescidos sobre vidro utilizando a t?cnica de deposi??o por descarga em gaiola cat?dica a fim de averiguar a influ?ncia das vari?veis de processo nas propriedades ?pticas e estruturais do filme. Como atmosfera do plasma foi utilizada a mistura de gases Ar, N2 e H2, fixando o fluxo de Ar e N2 em 4 e 3 sccm, respectivamente, e usando fluxos de 0, 1 e 2 sccm de H2. O processo de deposi??o foi monitorado por Espectroscopia de Emiss?o ?ptica (OES) para investiga??o das esp?cies ativas no plasma. Observou-se que com o aumento fluxo de H2 as intensidades das esp?cies luminescentes no plasma sofrem altera??es e que a esp?cie N2 (391,4 nm) n?o teve um crescimento proporcional ao fluxo de H2. Outros par?metros investigados foram o di?metro e o n?mero de furos da gaiola. As an?lises de difra??o de raios X com ?ngulo de incid?ncia rasante (GIXRD) comprovaram que os filmes obtidos s?o compostos por TiN, podendo ter varia??es quanto a quantidade de nitrog?nio na rede e o tamanho de cristalito; a microscopia ?ptica forneceu dados sobre a homogeneidade, a partir da microscopia de for?a at?mica (AFM) observou-se algumas caracter?sticas microestruturais do filme e a rugosidade. A espessura foi quantificada atrav?s das an?lises de elipsometria. As propriedades ?pticas como reflet?ncia e transmit?ncia (medidas por espectrofotometria) s?o bastante sens?veis a altera??es na rede cristalina do material, composi??o qu?mica e espessura, sendo, portanto, uma boa ferramenta para verifica??o do controle do processo. De maneira geral, os filmes obtidos com fluxo de 0 sccm de H2 possuem uma maior transmit?ncia atribu?da ao menor cristalinidade decorrente da maior quantidade de nitrog?nio na rede cristalina do TiN. Os filmes obtidos nos fluxos de 1 e 2 sccm de H2 obtiveram um aspecto dourado e o difratograma apresentou picos caracter?sticos do TiN com maior intensidade e menor largura a meia altura, sugerindo que com a presen?a de hidrog?nio na atmosfera do plasma os filmes s?o mais estequiom?tricos e com maior cristalinidade. Quanto ? configura??o da gaiola observou-se que com maior quantidade de furos na tampa, maior a proximidade da tampa com a amostra e menor o di?metro do furo, maior ? a espessura do filme, o que ? justificado pela maior probabilidade das esp?cies do plasma atingirem efetivamente o substrato e promoverem o crescimento do filme

Made available in DSpace on 2014-12-17T14:09:18Z (GMT). No. of bitstreams: 1 JulianaAA_TESE.pdf: 2312979 bytes, checksum: 31c1a19cbf37d537febd576ec54e5eb2 (MD5) Previous issue date: 2013-09-13 / Discrepancies between classical model predictions and experimental data for deep bed filtration have been reported by various authors. In order to understand these discrepancies, an analytic continuum model for deep bed filtration is proposed. In this model, a filter coefficient is attributed to each distinct retention mechanism (straining, diffusion, gravity interception, etc.). It was shown that these coefficients generally cannot be merged into an effective filter coefficient, as considered in the classical model. Furthermore, the derived analytic solutions for the proposed model were applied for fitting experimental data, and a very good agreement between experimental data and proposed model predictions were obtained. Comparison of the obtained results with empirical correlations allowed identifying the dominant retention mechanisms. In addition, it was shown that the larger the ratio of particle to pore sizes, the more intensive the straining mechanism and the larger the discrepancies between experimental data and classical model predictions. The classical model and proposed model were compared via statistical analysis. The obtained p values allow concluding that the proposed model should be preferred especially when straining plays an important role. In addition, deep bed filtration with finite retention capacity was studied. This work also involves the study of filtration of particles through porous media with a finite capacity of filtration. It was observed, in this case, that is necessary to consider changes in the boundary conditions through time evolution. It was obtained a solution for such a model using different functions of filtration coefficients. Besides that, it was shown how to build a solution for any filtration coefficient. It was seen that, even considering the same filtration coefficient, the classic model and the one here propposed, show different predictions for the concentration of particles retained in the porous media and for the suspended particles at the exit of the media / Discrep?ncias encontradas entre dados experimentais e previs?es feitas a partir do modelo cl?ssico foram relatadas por v?rios autores. Para entender essas discrep?ncias, um modelo anal?tico cont?nuo para a filtra??o profunda ? proposto. Neste modelo, cada mecanismo de reten??o est? associado a um coeficiente de filtra??o diferente. Foi mostrado que os coeficientes de filtra??o n?o podem ser somados e considerados em um ?nico coeficiente de filtra??o global como se apenas um mecanismo de reten??o atuasse no sistema, o que ? feito no modelo cl?ssico. Al?m disso, foram obtidas solu??es expl?citas para o sistema de equa??es que representam o modelo proposto. Tais solu??es foram usadas para ajustar os dados experimentais, e um bom ajuste foi obtido. Comparando os resultados obtidos com rela??es emp?ricas dispon?veis na literatura foi poss?vel identificar o mecanismo de reten??o mais atuante na filtra??o. Foi mostrado ainda, que quanto maior o tamanho das part?culas injetadas, mais atuante ? o mecanismo de exclus?o pelo tamanho e maiores as discrep?ncias entre o modelo proposto e o modelo cl?ssico. Os modelos cl?ssico e proposto foram comparados atrav?s de uma an?lise estat?stica. Tal an?lise mostrou que os ajustes feitos com o modelo proposto s?o significativamente melhores que os ajustes feitos com o modelo cl?ssico, principalmente quando o mecanismo de exclus?o pelo tamanho ? o mais atuante na filtra??o. Neste trabalho foi, tamb?m, estudado a filtra??o de part?culas em meio poroso com capacidade finita de filtra??o. Observou-se, neste caso, que ? necess?rio considerar mudan?as nas condi??es de fronteira com a evolu??o do tempo. Foi obtida a solu??o para tal modelo para diferentes fun??es de coeficiente de filtra??o. Al?m disso, foi mostrado como construir a solu??o para um coeficiente de filtra??o qualquer. Observou-se que, ainda que se considere o mesmo coeficiente de filtra??o, o modelo cl?ssico e o modelo proposto apresentam previs?es distintas para as concentra??es de part?culas retidas no meio e de part?culas em suspens?o na sa?da do meio

Tato studie je zaměřena na základní výzkum přípravy a-SiC:H a a-SiCO:H slitin plazmových polymerů pomocí metody plazmochemické depozice z plynné fáze (PE-CVD). Tyto slitiny byly připravovány depozicí z monomeru tetravinylsilanu (TVS) a jeho směsí s kyslíkem a argonem při různých efektivních výkonech pulzního plazmatu. Připravené tenké vrstvy byly za účelem získání závislostí optických, mechanických a chemických vlastností na depozičních podmínkách zkoumány pomocí metod spektros-kopické elipsometrie (ELL), nanoindentace (NI), fotoelektronové spektrometrie (XPS) a Fourierovy transformované infračervené spektrometrie