No presente trabalho descreve-se: a determinação da permitividade dielétrica complexa através de medidas de fase; a aplicação de técnicas de correlação e análise em séries de Fourier, para a determinação da fase, amplitude, qualidade e deformação do sinal atrasado; os circuitos eletrônicos do medidor de fase e do oscilador de U.B.F. programável; a programação desenvolvida em FORTRAN IV e MACRO-ASSEMBLER para o computador PDP 11/45, utilizado para operar o medidor de fase e o oscilador de U.B.F. / In the present work we describe: the determination of the complex dielectric permittivity by phase shift measurements; the application of correlation and Fourier series analyses to determine the phase shift, amplitude, quality and deformation of the shifted signal; the designed electronic hardware of the phase meter and programmb1e ultra-low frequency oscillator; the developed software written in FORTRAN IV and MACRO- ASSEMBLER for PDP 11/45, to operate the phase meter

Made available in DSpace on 2016-08-19T12:56:35Z (GMT). No. of bitstreams: 1 SINARA DE FATIMA FREIRE DOS SANTOS.pdf: 5017143 bytes, checksum: 47814d067ba298cd245c1c37cd698b95 (MD5) Previous issue date: 2010-10-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The present work has the objective to purify the babassu and soy biodiesel using as adsorbent bentonite clay and talc, under monitoring by measurements of dielectric constant, index of acidity and humidity test. Initially, it was determined the quality of babassu oil and soy through physic-chemical, then was synthesized methylic and ethylic biodiesel. The talc and bentonite adsorbents were characterized for their surface area, pore diameter, MEV, XRD and FTIR. During the purification of biodiesel was used some percentages of adsorbent (0.5, 1, 2, 3 and 4% for 50 g of biodiesel) and adsorption times of 20, 30, 60, 90 and 120 min, under constant agitation and ambient temperature, the results were compared with the process of washing with acidified water, by monitoring with measurements of dielectric constant, acidity index and humidity test. The evaluation of the purification of biodiesel by dry washing, monitored by dielectric constants, got better answers than the process of washing with acidified water, with lower values of dielectric constant around 4.0% of adsorbent and 120 min of adsorption time .In relation to the index of acidity and the humidity test, samples of purified biodiesel with the adsorbent are in accordance with the specifications of the National Agency of Petroleum, Natural Gas and Biofuels (ANP). Therefore, it is considered that the methodology for dry washing, as well as monitoring by dielectric constant, is feasible as a method of purification and monitoring, respectively, using as references the results of conventional purification process. / O presente trabalho tem o objetivo de otimizar as condições do processo de purificação a seco de biodiesel, utilizando como adsorvente a bentonita e o talco, sob monitoramento por medidas de constante dielétrica, índice de acidez e teor de umidade. Inicialmente, foi determinada a qualidade dos óleos de babaçu e soja através de testes físico-químicos, em seguida foi sintetizado o biodiesel metílico e etílico. Os adsorventes foram caracterizados por adsorção de nitrogênio, microscopia eletrônica de varredura, difração de raios-X e infravermelho. Durante a purificação do biodiesel utilizou-se várias percentagens de adsorventes (0,5, 1, 2, 3 e 4% por 50 g de biodiesel) e tempos de adsorção de 20, 30, 60, 90 e 120 min, sob agitação constante e temperatura ambiente, os resultados foram comparados com o processo de lavagem com água acidificada, através do monitoramento com medidas de constante dielétrica, índice de acidez e teor de umidade. A avaliação da purificação do biodiesel por lavagem a seco, monitorada por constantes dielétricas, obteve respostas melhores que o processo de lavagem com água acidificada, com menores valores de constante dielétrica em torno de 4,0 % de adsorvente e 120 min de tempo de adsorção. Em relação ao índice de acidez e o teor de umidade, as amostras de biodiesel purificadas com os adsorventes, estão de acordo com as especificações da Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP). Portanto, considera-se que a metodologia por lavagem a seco, bem como, o monitoramento por constante dielétrica, é viável como método de purificação e monitoramento, respectivamente, usando como referências os resultados obtidos do processo de purificação convencional.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22159号 / 工博第4663号 / 新制||工||1727(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 田中 功, 教授 中村 裕之, 教授 邑瀬 邦明 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

In this thesis, different methods for measuring the relative dielectric constant is investigated using simulations and experimental approaches. The first method is known as the S-parameter inversion method. In this method formulae is used to calculate the characteristic impedance of the microstrip line from measured S-parameters. To calculate the value of relative dielectric constant, four expressions for the microstrip line that relate the characteristic impedance to the relative dielectric constant were used. Second method uses an implementation of a band-pass filter and is commonly known as the band-pass filter method. In this method, a band-pass microstrip filter was designed using a predicted relative dielectric constant value. Center frequency of the band-pass filter is chosen to be at the frequency of interest, since relative dielectric constant will be determined around this frequency. The designed band-pass filter was manufactured and the frequency response was measured. To determine the true relative dielectric constant one changes the relative dielectric constant parameter used in the simulation until it matches the measured response of the manufactured PCB. Third method is called the quarter wavelength stub method. It uses implementations of a microstrip quarter wavelength stub because it resonance at different frequencies. The relative dielectric constant is determined using the frequencies on which the reflection occurred. In the fourth method, called the two microstrip line method, two lines of different lengths were designed and the phase difference between the propagating waves were measured. The phase difference and difference in length of the two lines is then used to calculate the relative dielectric constant. The thesis shows that a majority of the methods generates a similar result, thus indicates that they are suitable to determine the relative dielectric constant of any given substrate. The two methods that gave the most accurate results are the quarter wavelength stub method and the band-pass filter method. S-parameter inversion method is the method that has high variations in the results. Since the characteristic impedance that is calculated using the S-parameters are sensitive towards any sort of disturbances. The resulting relative dielectric constant aren't within the expected range for FR-4 both higher and lower values were obtained. The band-pass filter method gives the most accurate results of the methods. As the resulting relative dielectric constant are within the expected range for FR-4. Quarter wavelength stub method gives the results of the relative dielectric constant that are within the expected values of FR-4 and the variation is moderate. Two microstrip line method shows deviations in the results and has non-linearity as well. This is probably coming due to resonance of the line that gives rise to a phase change. This method is also acceptable since the results of the relative dielectric constant are within the expected range for FR-4.

abstract: This study aims to address the deficiencies of the Marcus model of electron transfer (ET) and then provide modifications to the model. A confirmation of the inverted energy gap law, which is the cleanest verification so far, is presented for donor-acceptor complexes. In addition to the macroscopic properties of the solvent, the physical properties of the solvent are incorporated in the model via the microscopic solvation model. For the molecules studied in this dissertation, the rate constant first increases with cooling, in contrast to the prediction of the Arrhenius law, and then decreases at lower temperatures. Additionally, the polarizability of solute, which was not considered in the original Marcus theory, is included by the Q-model of ET. Through accounting for the polarizability of the reactants, the Q-model offers an important design principle for achieving high performance solar energy conversion materials. By means of the analytical Q-model of ET, it is shown that including molecular polarizability of C60 affects the reorganization energy and the activation barrier of ET reaction. The theory and Electrochemistry of Ferredoxin and Cytochrome c are also investigated. By providing a new formulation for reaction reorganization energy, a long-standing disconnect between the results of atomistic simulations and cyclic voltametery experiments is resolved. The significant role of polarizability of enzymes in reducing the activation energy of ET is discussed. The binding/unbinding of waters to the active site of Ferredoxin leads to non-Gaussian statistics of energy gap and result in a smaller activation energy of ET. Furthermore, the dielectric constant of water at the interface of neutral and charged C60 is studied. The dielectric constant is found to be in the range of 10 to 22 which is remarkably smaller compared to bulk water( 80). Moreover, the interfacial structural crossover and hydration thermodynamic of charged C60 in water is studied. Increasing the charge of the C60 molecule result in a dramatic structural transition in the hydration shell, which lead to increase in the population of dangling O-H bonds at the interface. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2019

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The dielectric constant or relative static permittivity of a material represents the capacitance of the material relative to a vacuum and is important in many industrial applications. Nevertheless, accurate experimental values are often unavailable and current prediction methods lack accuracy and are often unreliable. A new QSPR (quantitative structure-property relation) correlation of dielectric constant for pure organic chemicals is developed and tested. The average absolute percent error is expected to be less than 3% when applied to hydrocarbons and non-polar compounds and less than 18% when applied to polar compounds with dielectric constant values ranging from 1.0 to 50.0. A local composition model is developed for mixture dielectric constants based on the Nonrandom-Two-Liquid (NRTL) model commonly used for correlating activity coefficients in vapor-liquid equilibrium data regression. It is predictive in that no mixture dielectric constant data are used and there are no adjustable parameters. Predictions made on 16 binary and six ternary systems at various compositions and temperatures compare favorably to extant correlations data that require experimental values to fit an adjustable parameter in the mixing rule and are significantly improved over values predicted by Oster's equation that also has no adjustable parameters. In addition, molecular dynamics (MD) simulations provide an alternative to analytic relations. Results suggest that MD simulations require very accurate force field models, particularly with respect to the charge distribution within the molecules, to yield accurate pure chemical values of dielectric constant, but with the development of more accurate pure chemical force fields, it appears that mixture simulations of any number of components are likely possible. Using MD simulations, the impact of different portions of the force field on the calculated dielectric constant were examined. The results obtained suggest that rotational polarization arising from the permanent dipole moments makes the dominant contribution to dielectric constant. Changes in the dipole moment due to angle bending and bond stretching (distortion polarization) have less impact on dielectric constant than rotational polarization due to permanent dipole alignment, with angle bending being more significant than bond stretching.

Целью данной работы является исследование методов определения электродинамических параметров диэлектрических материалов. В ходе выполнения работы были рассмотрены основные методы измерения в области высоких, сверхвысоких и крайне высоких частот, а также реализованные измерительные комплексы, предлагаемые ведущими производителями измерительного оборудования. В результате выполненной работы был выбран и реализован метод измерения параметров диэлектрических материалов, разработано программное обеспечение, необходимое для реализации измерительного комплекса. По результатам работы были проведены практические измерения и сделаны выводы о применимости разработанного измерительного комплекса. Актуальность работы объясняется необходимостью использования значений электродинамических параметров диэлектрика при разработке электронных устройств. / Were investigated different methods of define electrodynamic properties of dielectric materials. During this work was illuminated main methods of material properties measurements in RF domain. Was developed program for measurement a permittivity of material using a waveguide and an air line using vector network analyzer. The results of this work were define permittivity of different materials and analysis those results with errors explanation.