Silicon based hydrogenated amorphous semiconducting (intrinsic and n/p doped a-Si:H and a-Si1-xCx:H) thin films have been deposited by plasma enhanced chemical vapor deposition (PECVD) system. In order to analyze the optical response of these amorphous films, intrinsic optical absorption mechanisms have resumed and spectral variations of absorption coefficient &amp / #61537 / (E) are derived. The exponential variation of absorption coefficient for energies below the band edge is discussed in the frame of randomly distributed square well like potential fluctuations of localized states. Urbach constant EU and the slope B are deduced as disorder parameters. Both intensity sensitive transmittance and reflectance, and amplitude/phase sensitive ellipsometric techniques for multilayer thin films are theoretically and practically treated. Various methodologies are developed for the determination of thickness, refractive index and absorption coefficient of the films. A reflectance unit is adapted to the spectrometer and all the measuring instruments are computerized and relevant software packets have been developed. IR spectroscopy has been used for determination of mainly hydrogen concentrations and bonding properties. Establishing the production-characterization-improved growth conditions cycle successfully, the following results are obtained: (a) determination of lateral inhomogeneity of films along the radial direction of the plasma reactor, (b) determination of vertical inhomogeneity due to both substrate and air ambient, (c) perfect adjustment of refractive index and band gap of a-Si1-xCx:H films by changing carbon content of the films, (d) effect of plasma power density on both growth and carbon content.

abstract: This work focuses on simulation of electrical resistivity and optical behaviors of thin films, where an Ag or Au thin layer is embedded in zinc oxide. Enhanced conductivity and transparency were earlier achieved with multilayer structured transparent conducting oxide (TCO) sandwich layer with metal (TCO/metal/TCO). Sputtering pattern of metal layer is simulated to obtain the morphology, covered area fraction, and the percolation strength. The resistivity as a function of the metal layer thickness fits the modeled trend of covered area fraction beyond the percolation threshold. This result not only presents the robustness of the simulation, but also demonstrates the influence of metal morphology in multilayer structure. Effective medium coefficients are defined from the coverage and percolation strength to obtain simulated optical transmittance which matches experimental observation. The coherence of resistivity and optical transmittance validates the simulation of the sputtered pattern and the incorporation of percolation theory in the model. / Dissertation/Thesis / M.S. Materials Science and Engineering 2012

Este trabalho estuda a propagação da luz no esmalte e dentina humanos, através da transmitância direta e absorbância no intervalo de comprimento de onda de 200 a 3200nm, e através da transmitância total no intervalo de onda de 380 a 760nm. Foram utilizadas secções de 30 molares humanos íntegros, que foram seccionados nos sentidos VL (vestíbulo – Lingual), MD (mésio distal) e OC (ocluso cervical). As espessuras utilizadas foram de 0,5mm e 0,25mm. Foram agrupados 5 dentes para cada sentido para cada espessura. Esmalte e dentina estavam presentes de maneira simultânea na mesma amostra. A absorbância foi calculada, a partir dos espectros de transmitância direta, aplicando-se a Lei e Beer-Lambert. Os espectros de transmitância total foram obtidos no espectro visível, e comparados, em média, com os espectros de transmitância direta no mesmo intervalo, para obter a energia difusa das amostras. Os espectros UV (Ultravioleta), VIS (Visível) e IV (Infravermelho), foram tratados separadamente para cada tecido e espessura. No infravermelho foram identificados os picos de transmitância e absorbância para ambos os tecidos. Os valores de transmitância e absorbância para cada faixa espectral foram tratados pela ANOVA, e os grupos comparados pelo teste de intervalo de confiança (95%). Os resultados mostraram que, as propriedades ópticas do esmalte e dentina diferem no que diz respeito as 3 faixas espectrais testadas. Os resultados também mostram que as propriedades ópticas são dependentes da espessura e do sentido de seccionamento dos dentes. A pesar das diferenças apresentadas entre os espectros, as curvas espectrais mostraram um padrão semelhante para todas as amostras de dentina e de esmalte, independente da espessura. Este comportamento possibilitou a identificação de picos comuns nos espectros estudados. / This research studies the propagation of light in the human enamel and dentine, through direct transmittance and absorbance in the 200 to 3200nm wavelength interval, and through total transmittance in the 380 to 760nm wavelength interval. The study employed sections of 30 human integral molars, which were sectioned in the VL directions (vestibule – Lingual), MD (mesio distal), and OC (occlusion cervical). The thicknesses used were from 0.5mm to 0.25mm. Five teeth were grouped in each direction for each thickness. Enamel and dentine were simultaneously present in the same sample. Absorbance was calculated from the direct transmittance specters, applying the Beer-Lambert Law. Total transmittance specters were obtained in the visible specter, and compared, on average, with the Total transmittance specters in the same interval, to obtain the diffuse energy of the samples. UV (Ultraviolet), VIS (Visible), and IV (Infrared) specters, were treated separately for each tissue and thickness. In infrared, the transmittance and absorbance peaks were identified for both tissues. The transmittance and absorbance spectral range were treated by ANOVA, and the groups compared by the confidence interval test (95%). The results showed that the optical properties of the enamel and dentine differ with regard to the three tested spectral ranges. The results also showed that the optical properties are dependent on the thickness and the direction of the sectioning of the teeth. Despite the differences found between the specters, the special curves showed a similar pattern for all samples of dentine and enamel, independently of the thickness. This behavior allowed the identification of common peaks in the specters under study.

Orientador: Edison Bittencourt / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T05:15:57Z (GMT). No. of bitstreams: 1 Fregolente_PatriciaBogalhosLucente_M.pdf: 761293 bytes, checksum: da2a8c420bdda1b10fb1d7888911e1b9 (MD5) Previous issue date: 2006 / Resumo: Atualmente, o mercado procura materiais com qualidades ópticas que satisfaçam as exigências dos usuários e que possuam facilidades de processamento. De forma geral, para um polímero apresentar boas propriedades ópticas, este necessita ter boas características como alto índice de refração, alta transmitância da luz, baixo peso específico, resistência ao impacto, estabilidade dimensional pós cura e estabilidade por exposição à luz e ao calor. Industrialmente, utiliza-se para a fabricação de lentes oftálmicas, a técnica de polimerização térmica, ou cura térmica. Dessa maneira, necessita-se de um tempo de cura muito longo (cerca de 20 horas) para evitar defeitos nas lentes. Entretanto, a cura através de irradiação de luz ultra-violeta (UV) permite obter os mesmos tipos de materiais e com características semelhantes com um tempo de processo reduzido em até poucos minutos. No presente trabalho, para confecção das lentes foram estudados os seguintes monômeros e oligômeros: metacrilato de metila (MAM), 1,6-Hexanediol diacrilato (HDODA), diacrilato uretano alifático tetrafuncional (Ebecryl 284) e diacrilato epóxi bisfenol-A (Ebecryl 3700) e para cada formulação o fotoiniciador 2- hidroxi-2-metil-1-fenilpropanona (Darocure 1173). O tempo de fotocura da mistura dura entre 4 a 7 minutos, de acordo com a espessura do molde. As lentes obtidas foram caracterizadas por medidas de dureza Shore D, transmitância nas regiões visível, UVA e UVB, índice de refração, análises térmicas para determinação da temperatura de transição vítrea. As lentes foram recobertas por uma resina multifuncional através do método de deposição por spin-coating e curada por UV. A caracterização dessa camada foi realizada por testes de dureza superficial utilizando graduações de grafites além de um planejamento experimental para observar as variáveis do processo de spin-coating que mais interferem na formação do recobrimento. As lentes produzidas apresentam ótimas qualidades ópticas e mecânicas e esta tecnologia de fotocura apresenta grande potencial para ser aplicada e produzir lentes em escala industrial / Abstract: The materials used for ophthalmic lenses need to present some optical qualities and to satisfy the requirements of the users. Various characteristics are required for the transparent synthetic resins as optical material. A polymer, to have good optical properties, needs to be colorless and tranparent, present good characteristics as high refractive index, high light transmittance, low specific weight, impact resistance, and stability to the exposition to the light and the heat. Industrially, for the manufacture of opthalmic lenses is used the technique of thermal polymerization, or thermal cure. This way, it is needed a long time of cure (about 20 hours) to prevent defects in the lenses. The monomers and monofunctional and multi-functional oligomers that have been studied for production of the lenses are methyl methacrylate (MAM), 1,6-hexanediol diacrylate (HDODA), aliphatic uretane diacrylate and bisphenol A epoxy diacrylate. The photoinitiator 2-hydroxi-2-methyl-1-fenilpropanone was added to each mixture, varying its concentration of 1 to 3%. The cure through ultraviolet irradiation (UV) allows to get the same kind of materials than thermal cure with similar characteristics but with a time of processing of the order of few minutes. In the present work, characteristics as refractive index (n), heat resistance, light transmittance and hardness of the produced lenses were studied from mixtures of acrylates and multi-functional methacrylates through photopolymerization with UV lamp at room temperature. The pencil hardness test was used for characterize the surface coating by spin-coating method, beyond an experimental design to observe the variables of the process that influence the formation of the coating / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

O objetivo desta pesquisa foi avaliar a transmitância de diferentes tipos e cores de cerâmicas e seus efeitos no grau de conversão (GC) de dois tipos de cimentos resinosos com modo de polimerização dual. Foram confeccionadas 60 pastilhas com a cerâmica IPS e.max (Ivoclar Vivadent, Schaan, Liechtenstein) e divididas em 3 grupos: LT, MO e Z, com 20 pastilhas cada um. Nos grupos LT e MO, as pastilhas foram confeccionadas com a cerâmica de dissilicato de lítio de baixa translucidez (LT - low transluscency) e de média opacidade (MO - medium opacity), respectivamente. No grupo Z, as pastilhas foram confeccionadas em zircônia. Cada grupo foi subdividido em 5 subgrupos (n=4), de acordo com a cor da cerâmica: A2; A3,5; B2; C2; D3. No grupo LT, as pastilhas foram prensadas nas cores anteriormente citadas e, nos grupos MO e Z, as pastilhas foram, inicialmente, confeccionadas para simular infraestruturas e, posteriormente, receberem aplicação de cerâmica de revestimento IPS e.max Ceram (Ivoclar Vivadent, Schaan, Liechtenstein) nas mesmas cores. O espectrofotômetro UV 1800 Shimadzu foi utilizado para medir a transmitância de cada espécime de cerâmica (2,0 mm de espessura). Para medir o GC, espécimes dos cimentos resinosos Variolink II (Ivoclar Vivadent, Schaan, Liechtenstein) e Rely X U200 (3M ESPE, St. Paul, MN, USA), com espessura de 100 μm, foram fotopolimerizados sob os discos de cerâmica por 40 s. Espécimes dos cimentos fotoativados sem a interposição da cerâmica foram usados como grupo controle. A polimerização dos cimentos foi avaliada através da espectrometria no infravermelho com transformada de Fourier (FTIR) empregando o método de reflexão atenuada total (ATR) imediatamente após a fotopolimerização. Os resultados foram submetidos aos testes ANOVA a 1 critério e Teste de Tukey (α=5%). Os valores de transmitância foram inferiores a 1%, sendo que as do grupo LT apresentaram, em geral, os maiores valores de transmitância, seguidos dos grupos MO e Z. O GC do cimento Variolink II não sofreu influência da interposição da pastilha de cerâmica. Para o cimento Rely X U200, a interposição de alguns tipos/cores de cerâmica (LT A3,5; MO A2; MO A3,5 e Z A3,5) diminuíram o GC em relação ao grupo controle. Concluiu-se que os valores de transmitância e GC foram influenciados pelos tipos/cores de cerâmica. Entretanto, somente o grupo formado pela cerâmica de dissilicato de lítio LT, usando o Rely X U200, apresentou correlação negativa entre transmitância e GC. / The aim of the present study was to evaluate the transmittance of different ceramic types and shades and their effects on the degree of conversion (DC) of two dual-cure resin cements. Sixty discs were fabricated with IPS e.max ceramic (Ivoclar Vivadent, Schaan, Liechtenstein) and divided into three groups (n= 20 in each group): LT, MO and Z. For LT and MO groups discs were fabricated with low translucency (LT) and medium opacity (MO) lithium disilicate ceramic, respectively. Discs from Z group were manufactured of zirconia. Each group was divided into five subgroups (n = 4), according to the ceramic shade: A2; A3,5; B2; C2; D3. In the LT group, specimens were heat-pressed in shades cited above and in the MO and Z groups, the discs were initially fabricated as core materials and then veneered with veneer ceramic (IPS e.max Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) in the same shades. A spectrophotometer UV-1800 Shimadzu was used to determine the transmittance percentage of each ceramic specimen (2.0-mm-thick). For DC measurements, the resin cements (Variolink II - Ivoclar Vivadent, Schaan, Liechtenstein and Rely X U200 - 3M ESPE, St. Paul, MN, USA) specimens (thickness: 100 μm) were photocured under the ceramic discs (2.0-mm-thick) for 40 s. Specimens photocured without the ceramics discs were used as control group. ATR/FTIR spectrometry was used to evaluated the extent of polymerization for all cement specimens immediately after photocuring. The results were submitted to one-way ANOVA and Tukey test (α=5%). The transmittance percentage was less than 1% and the LT group had the highest transmittance values, followed by MO and Z groups. The %DC of Variolink II cement was not influenced by the ceramic disc interposition. For Rely X U200 cement, the interposition of some ceramics types/shades (LT A3,5, MO A2, MO A3,5 and Z A3,5) significantly decreased the %DC compared to control group. It was concluded that the transmittance values and %DC were influenced by the ceramics types/shades. However, only the LT group, using the Rely X U200, showed a negative correlation between transmittance and %DC.

Medidas de transmitância em óculos de sol fazem parte de alguns dos testes propostos pela norma NBR15111, porém, observou-se que não há no país um sistema preciso para medidas de transmitância que não seja com o uso de espectrofotômetros e pessoas qualificadas para utilizar o equipamento, aplicar as funções de ponderação e fornecer laudos técnicos sobre a lente testada. Assim, o trabalho propõe métodos que utilize componentes simples e resulte na construção de um equipamento que possa fornecer a informação sobre as transmitâncias dos filtros de óculos de sol de forma automática, de acordo com a NBR15111. Foi feita a espectrofotometria de 45 lentes de óculos de uso geral, e calculadas suas respectivas transmitâncias (luminosa, ultravioleta, semafórica), como amostras de comparação com as metodologias testadas. Os testes incluíram lâmpadas e LEDs como fontes de emissão para a região do espectro visível e lâmpadas fluorescentes para a região ultravioleta, além de sensores específicos para cada região espectral, e eletrônica de controle e aquisição dos sinais. Foram usadas ferramentas de análise estatística, como erro RMS, coeficiente de aderência (GFC) e análise de Bland-Altman. Aproximadamente 62% dos óculos testados foram reprovados para a direção no trânsito e nenhum foi reprovado para a proteção UV. Os métodos RMS e GFC apontaram combinações entre fonte e sensor que conseguem fazer a ponderação com os menores desvios-padrão das medidas espectrométricas. O sistema para teste UV mostrou melhoria significativa em relação aos desenvolvidos anteriormente, com um desvio padrão de 4,45 pontos percentuais e o sistema para testes na região visível utilizou o sensor TCS, no qual a regressão polinomial mostrou melhores resultados que as redes neurais artificiais, com os menores limites de concordância para as transmitâncias. Um número maior de amostras pode melhorar os métodos para que se obtenha uma aproximação ideal para todos os óculos de sol. Uma montagem com LEDs se apresenta como uma alternativa interessante quanto ao custo, tamanho e baixo consumo para medidores de transmitância portáteis. Desenvolveu-se um sistema com módulos para teste UV, Visível e Semafórico, para uso público no campus da USP de São Carlos, proporcionando conscientização e extensão dos estudos em relação aos óculos solares, contribuindo efetivamente com a população brasileira. / Transmittance measurements in sunglasses are a part of the standard tests proposed by NBR15111, however, it was observed that there is no accurate system for measuring transmittance different than using spectrophotometers and skilled practitioner to manage the equipment, apply the weighting functions and provide technical reports on the lens tested. Therefore, this study proposes methodologies using simple components and that can result a device that can provide information about sunglass filters automatically, according to NBR15111. Spectrophotometry was calculated in 45 lenses of sunglasses for general use, and their respective transmittance (visible, ultraviolet, traffic light), used as samples for testing the methodologies. The tests included lamps and LEDs as light sources for the visible region spectrum and fluorescent lamps for ultraviolet region, specific sensors for each spectral region, and electronic for control and signal acquisition. Statistical analysis tools were used, such as RMS error, goodness-of-fit coefficient (GFC) and the Bland - Altman analysis. Approximately 62% of the tested lenses failed in the test for signal light recognition and none has failed for UV protection. The RMS and GFC methods indicated combinations between source and sensor that calculated transmittance with the lowest standard deviations of the spectrometric measurements. The system for testing UV showed improvement compared to other previously equipment, with a standard deviation of 4.45 and the system for testing the visible region used the TCS sensor, in which the polynomial regression showed better results than artificial neural networks. A larger number of samples can improve the methods in order to obtain an optimal calibration that includes all sunglasses. LEDs seem to be a good alternative in terms of cost, size and low power consumption for portable transmittance meters. We developed a system with modules for testing UV, Visible and Traffic Light transmittance for public use on the USP São Carlos campus, providing awareness and extent of studies about the sunglasses, in order to contribute more effectively to the Brazilian population.

P-type transparent conductors are needed for a wide range of applicationssuch as solar cells and electrochromic smart windows. Solar power is animportant form of energy in today’s society as the threat of global warmingpushes the world towards fossil free energy. Hence a lot of solar cell typeshave been developed, among them tandem cells which are to different typesof solar cells stacked on top of each other. If one of the cells is based ona perovskite, a transparent p-type thin film electrode is needed as a holeconductor and electron blocking layer between the two cells. Nickel oxide(NiO) is a good candidate for this application as it has desired propertiessuch as good hole conduction, a high band gap and a matching work functionto the perovskite. The transmittance of as deposited NiO films by reactivemagnetron sputtered is limited so post deposition annealing is used to increasethe transmittance. This is not possible in this solar cell application as parts ofthe solar cell stack is temperature sensitive.Electrochromic smart windows contain a layer that can change its opticalproperties with the application of a voltage. Such windows are used inbuildings to increase energy efficiency and they contain an electrochromicdevice where NiO is used as an electrode as it has electrochromic properties,but just like with the solar cells, the transmittance of NiO is limited. Thisstudy investigates whether it is possible to make as deposited NiO by reactivemagnetron sputtering transparent, eliminating the need for post depositionannealing. Such a deposition process was found using different sputtermachines with the process point on the edge between metal and oxide modein terms of oxygen flow. This resulted in highly transparent and highlyresistive NiO films with a much higher deposition rate than in oxide mode.

No description available.

[pt] A previsão da energia elétrica produzida com energia solar pode ser usada para monitorar em tempo real seu desempenho, permitindo a identificação de problemas operacionais ou sua degradação, assim como a previsão da produção de energia elétrica a curto e médio prazo, permitindo otimizar o uso da rede. Normalmente, a previsão de dados climáticos ao longo do dia serve para ajudar a estabilidade da rede elétrica. Já a previsão de dados para um dia ou mais à frente serve para apoiar a participação de mercado. Esta pesquisa tem como objetivo geral propor um modelo de previsão a curto prazo da irradiação solar a partir de correlações de condições climáticas, visando diminuir as incertezas de previsão da mesma, que pode ser usado para prever a geração fotovoltaica. O modelo de previsão proposto se baseia em identificar os dias de céu limpo, caracterizados pela ausência de nuvens, e dias totalmente nublados. Para sua identificação, foram utilizadas formulações já consagradas na literatura. Para os demais dias, a previsão da irradiação é feita a partir de regressões e correlações entre temperatura ambiente e transmitância atmosférica. A escolha do modelo de céu limpo é um fator preponderante para a previsão, podendo aumentar significativamente sua confiabilidade. Diversos modelos de previsão foram avaliados e combinados para uma melhor previsão da irradiação solar média incidente na superfície terrestre. A partir de dados de irradiação solar e temperatura, medidos a cada minuto por quatro anos na cidade de Miranda do Norte, Maranhão, foi possível analisar, interpretar e propor um modelo para a previsão da irradiação solar média com incertezas de 22-24 porcento, 14-16 porcento, 13-15 porcento e 12-13 porcento, a nível de confiabilidade de 95,45 porcento, respectivamente para horizontes de 1, 3, 5 e 7 dias à frente. A utilização do método dos mínimos quadrados para previsão apresenta incertezas muito maiores. O modelo proposto apresenta-se eficaz para prever a irradiação solar. Sua utilização e facilidade de implementação podem ser de grande valia para a prever o planejamento diário e semanal da produção de usinas fotovoltaicas. Foi usado o modelo de previsão sugerido por Bindi, juntamente com três modelos de céu limpo para redução da incerteza de previsão. / [en] The prediction of the electric energy production by solar energy systems can be used as a real time monitoring of its performance, allowing the identification of operational problems or its performance degradation, as well as the short and medium term production of electric energy, thus optimizing the use of the electric network. Normally, the daylong climactic data prediction is useful for helping stabilizing the electric network. The one or more day ahead prediction of electric energy is a useful tool for planning the energy supply to the market. The main goal of this research is to propose a short-term prediction model for the solar irradiation by means of weather condition correlations, in doing so, we expect to lower the uncertainties of the solar irradiation forecast, for which can be used to forecast photovoltaic energy. The proposed prediction model uses literature available correlations for clear sky (no clouds) and overcast days, to predict the solar irradiation in other days, through the use the ambient temperature and atmospheric transmission literature available correlations. Several prediction models were used and combined for 1, 3, 5 and 7 days ahead prediction of the available average solar energy in that time interval . It was concluded that the clear sky model plays an important role in the prediction reliability. Experimental data taken every minute for almost four years in the city of Miranda do Norte in the state of Maranhão, Brazil, were used to verify and propose a model to better predict the available solar energy irradiation, to within 22-24 percent, 14-16 percent, 13-15 percent and 12-13 percent uncertainty (95,45 percent confidence level), respectively for 1, 3, 5 and 7 days ahead of the available solar irradiation in the time interval. The least square model was also analyzed and it was shown to predict the solar irradiation with much higher uncertainties. As a result, the proposed model can be easily implemented for predictions in other places and can be very useful for predicting and planning the daily and weekly output of photovoltaic plants. In this dissertation the prediction model suggested by Bindi was utilized, together with three clear sky models to reduce the prediction uncertainty.

Particle suspension is a phenomenon when solid particles get trapped in a liquid. This phenomenon is a common occurrence in the water treatment industry. It is typically measured continuously throughout the treatment process to ultimately ensure high water-quality. Cerlic Controls AB specializes in developing sensors for the water treatment industry and have been doing so since 1977. Cerlic Control's sensors are used within the various stages of water-purification. The type of sensor central to this project uses transmission of light to determine a concentration of suspended particles. This project describes the development-process for one of Cerlic Controls existing embedded systems. The embedded system is undergoing a modernization process where the electronics and software are updated to a more modern design. This report describes the improvements to the measurement range while maintaining the same or improved resolution. These improvements are mostly performed by modern electronics and more advanced signal processing techniques in comparison to the previous implementation. A large portion of the previous implementation's software was split over two embedded systems due to limitations in processing power. This modern version focuses on bringing these two systems into one. The sensor's microprocessor has been replaced with a more modern higher performance alternative which allows all computations to be performed in the sensor. Linearity and stability are key aspects defining system performance. Optical filters block a certain amount of light and are heavily used in verification of performance. Suspensions using activated carbon were also used to evaluate the measurement range. The results of the project were largely successful. An initial implementation was achieved with optimistic results, but further work must be done before the sensor is ready for use in industry.