Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Matemática e Computação Científica. / Made available in DSpace on 2012-10-21T12:20:40Z (GMT). No. of bitstreams: 0 / Este trabalho apresenta aspectos básicos da teoria da distribuição de primos. A ênfase é em aspectos "elementares", onde este termo técnico deve significar que é evitado o uso de cálculo complexo. O uso de cálculo complexo começou com Riemann e permanece a técnica mais importante no estudo da distribuição dos primos. Técnicas elementares (no sentido acima) foram refinadas a ponto de permitir uma prova (Erdos e Selberg - 1949) do Teorema dos Números Primos. Uma prova assim foi durante muito tempo considerada impossível (Hardy e Ingham). A prova que apresentamos incorpora melhoramentos de Levinson cuja referência seguimos de perto. As provas elementares também evitam o uso da função zeta, mesmo com variável real. Parece-nos que um estudo desta função é crucial na distribuição dos primos. Os capítulos 3 e 4 deste trabalho fornecem os fundamentos de um tal estudo.

Made available in DSpace on 2015-09-17T15:25:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-26. Added 1 bitstream(s) on 2015-09-17T15:48:52Z : No. of bitstreams: 1 000845983_20151220.pdf: 230991 bytes, checksum: b740c5ad2a9a5fa8efefcb7c4a1bf5cc (MD5) Bitstreams deleted on 2015-12-22T10:26:35Z: 000845983_20151220.pdf,. Added 1 bitstream(s) on 2015-12-22T10:27:13Z : No. of bitstreams: 1 000845983.pdf: 719334 bytes, checksum: 516ab58505bb9db56413aca365162407 (MD5) / Estudou-se o efeito do comprimento das cadeias alquílicas (C12 e C18) e do contra íon (Br- e Cl-) dos lipídios catiônicos derivados de amônio quaternário, formadores de vesículas, brometo de didodecildimetilamônio (DDAB), brometo de dioctadecildimetilamônio (DODAB) e cloreto de dioctadecildimetilamônio (DODAC), na interação com o copolímero tribloco Pluronic® F127 (F127), formador de micelas. Foram investigadas as propriedades térmicas e estruturais das vesículas e micelas formadas. Foi fixada a concentração lipídica em 1 mM, na qual predominam vesículas unilamelares em dispersão aquosa e variada a concentração de F127 0,05 até 5mM. As amostras foram monitoradas pelas técnicas de turbidimetria, calorimetria diferencial de varredura (DSC), espalhamento dinâmico de luz (DLS) e espalhamento dinâmico eletroforético de luz (DELS). Os resultados indicam transição vesícula-micela, que ocorre em três estágios: no primeiro estágio, há predominância de vesículas mistas, no segundo estágio coexistem vesículas e micelas mistas e, no terceiro estágio, o sistema é dominado por micelas mistas. Os complexos formados consistem de vesículas ou de micelas mistas de lipídio/F127, respectivamente em baixas e altas concentrações do copolímero. Esses complexos vesiculares e micelares podem servir de modelos de lipoplexos e poliplexos na interação das vesículas e micelas mistas com ácido nucleico (DNA ou RNA), respectivamente. / It has been studied the effects of the alkyl chain length (C12 and C18) and counterion (Br - and Cl-) of the vesicle-forming quaternary ammonium cationic lipids from didodecyldimethylammonium bromide (DDAB), dioctadecyldimethylammonium bromide (DODAB) and dioctadecyldimethylammonium chloride (DODAC), on the interaction with the micelle-forming triblock copolymer Pluronic® F127(F127). Thermal and structural properties of vesicles and micelles formed were investigated. The lipid concentration was fixed at 1 mM at which predominantly unilamellar vesicles are formed in aqueous dispersion and varied the F127 concentration up to 5 mM. The samples were monitored by turbidimetry, differential scanning calorimetry (DSC), dynamic light scattering (DLS) and dynamic electrophoretic light scattering (DELS) techniques. The results indicate vesicle-micelle transition, which occurs in three stages: in the first stage there is predominance of mixed vesicles; in the second stage there co-exist mixed vesicles and micelles; and in the third stage the system is dominated by mixed micelles. The complexes formed consist of mixed vesicles or micelles from lipidF127, respectively at low and high copolymer concentrations. These vesicle and micelle complexes can serve as template for lipoplexes and polyplexes in the interaction of mixed micelles and vesicles with nucleic acid (DNA or RNA), respectively.

Made available in DSpace on 2015-06-18T02:05:31Z (GMT). No. of bitstreams: 1 000470517-Texto+Completo-0.pdf: 3643142 bytes, checksum: 1f5335f433b80cbcbe58f559422c4f72 (MD5) Previous issue date: 2015 / This work presents the simultaneous conduction mode (SCM), which is applied to the operation of the Zeta converter. This mode has the ability to implement an ideal power factor corrector (PFC) employing only one feedback control loop. In SCM, the current in the main switch and in the diode flows simultaneously within one of the operation stages. In SCM, the power converter presents characteristics of both conduction modes: continuous conduction mode (CCM) and discontinuous conduction mode (DCM). In SCM, the currents in the inductors of the power converter are never nullified, which is a typical behavior of the CCM. Nevertheless, the SCM does that while obtaining an ideal PFC with just one control loop. The SCM maintains its features, regardless of its control variable being the output current or the output voltage of the power converter. The solely application of a fixed duty cycle controller is enough to attain all these advantages, which is usually a feature of the DCM for PFCs of the flyback family. In order to validate the proposed technique, a complete study of the Zeta converter working in this new operation mode was performed. This study has included a qualitative and a quantitative power converter analysis. These analyses resulted in the development of a design methodology for the Zeta power converter working as a PFC in the SCM. In order to validate the present study, a prototype of the Zeta PFC for operation in the SCM was designed and built. This prototype was developed, as a case of study, to drive a power LED lamp (180°W). Thus, it was obtained the desired experimental confirmation for the research. The main advantage of the SCM, in comparison to the CCM, lies in its ability to maintain the input current of the PFC sinusoidal and in phase with the input voltage, which is imposed by the mains through the use of just a single PWM controller with fixed duty cycle. These results have, also, shown that the current peaks in the main semiconductors of the power converter are lower than their respective values in the DCM. However, this new operation mode results in the increase of the voltages on the main switch and diode in relation to the conventional power converter operation. The research of the application of the proposed method to other power converters is suggested to further works. / Este trabalho propõe a operação do conversor Zeta no modo de condução simultânea (MCS), cujo interesse reside na capacidade de implementação de um pré-regulador do fator de potência (PFP) ideal empregando apenas um laço de realimentação. Quando o conversor trabalha no MCS, a chave principal e o diodo conduzem simultaneamente em um de seus estágios de operação. Neste modo de condução, o conversor estático apresenta características de ambos os modos de condução conhecidos até agora: o modo de condução contínua (MCC) e o modo de condução descontínua (MCD). A operação no MCS resulta em um conversor estático operando como se estivesse no MCC, uma vez que a corrente nos indutores nunca se anula. Embora mantenha o conversor estático trabalhando com esta característica do MCC, o MCS permite a obtenção de um comportamento quase ideal do PFP, utilizando apenas um único controlador, seja ele de corrente ou de tensão, o qual mantém a razão cíclica do conversor constante, assim como usualmente ocorre com os PFPs da família redutor-elevador quando operam no MCD. Visando validar esta técnica, foi realizado um estudo do conversor operando desta forma que incluiu o desenvolvimento das análises qualitativa e quantitativa do conversor, as quais culminaram na elaboração de uma metodologia de projeto. Assim, realizou-se o projeto de um PFP, baseado no conversor Zeta, para energizar uma luminária LED de 180 W, operando no MCS, como estudo de caso. A luminária utilizada é o modelo High Power LED Baylight da empresa Luckysunny®. Os resultados obtidos experimentalmente validaram a estratégia proposta, uma vez que, com a operação do conversor Zeta no MCS reduz-se a ondulação (ripple) da corrente nos semicondutores em relação à operação no MCD. A principal vantagem da operação no MCS reside no fato deste manter a corrente de entrada do PFP senoidal em fase com a tensão imposta pela rede elétrica com apenas uma malha de controle da variável de saída de interesse seja ela tensão ou corrente como no estudo de caso em questão. Isto reduz o custo e a complexidade do controlador do conversor. Entretanto, esta estratégia apresenta sobretensão na chave principal e no diodo como principal desvantagem. Sugere-se a investigação da aplicação da metodologia de projeto proposta a outros conversores.

Neste trabalho, introduzimos a função zeta de Riemann \'ZETA\'(s), para s \'PERTENCE\' C \\ e apresentamos muito do que é conhecido como justificativa para a hipótese de Riemann. A importância de \'ZETA\' (s) para a teoria analítica dos números é enfatizada e fornecemos uma prova conhecida do Teorema dos Números Primos. No final, discutimos a importância de \'ZETA\'(s) para alguns modelos físicos de interesse e concluimos descrevendo como a hipótese de Riemann pode ser acessada estudando estes sistemas / In this work, we introduce the Riemann zeta function \'ZETA\'(s), s \'IT BELONGS\' C \\ and present much of what is known to support the Riemann hypothesis. The importance of \'ZETA\'(s) to the Analytic number theory is emphasized and a proof for the Prime Number Theorem is reviewed. In the end, we report on the importance of \'ZETA\'(s) to some relevant physical models and conclude by describing how the Riemann Hypothesis can be accessed by studying these systems

The counting of fuzzy subsets of a finite set is of great interest in both practical and theoretical contexts in Mathematics. We have used some counting techniques such as the principle of Inclusion-Exclusion and the Mõbius Inversion to enumerate the fuzzy subsets of a finite set satisfying different conditions. These two techniques are interdependent with the M¨obius inversion generalizing the principle of Inclusion-Exclusion. The enumeration is carried out each time we redefine new conditions on the set. In this study one of our aims is the recognition and identification of fuzzy subsets with same features, characteristics or conditions. To facilitate such a study, we use some ideas such as the Hamming distance, mid-point between two fuzzy subsets and cardinality of fuzzy subsets. Finally we introduce the fuzzy scanner of elements of a finite set. This is used to identify elements and fuzzy subsets of a set. The scanning process of identification and recognition facilitates the choice of entities with specified properties. We develop a procedure of selection under the fuzzy environment. This allows us a framework to resolve conflicting issues in the market place.

This thesis is concerned with finding meromorphic extensions to a half-plane containing zero for certain generating functions. In particular, we generalise a result due to Morita and use it to show that the zeta function associated to the geodesic flow over a quotient of a Schottky group can be meromorphically extended to a half-plane containing zero. Moreover, we show that the special value at zero can be calculated. These results are then generalised to obtain meromorphic extensions past zero for L-functions defined on quotients of Schottky groups and to provide an expression for the special value at zero. Finally we show that Morita's method can be adapted to provide a meromorphic extension to a half-plane containing zero for Poincaré series defined for a Schottky group, and that in special circumstances the value at zero can be calculated.

Orientador: Cesar Costapinto Santana / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-20T03:48:00Z (GMT). No. of bitstreams: 1 Sueyoshi_KennyHiroyassu_M.pdf: 16765508 bytes, checksum: 40833909580f433eff31bdb155fac71f (MD5) Previous issue date: 1994 / Resumo: Suspensões de argilas aditivadas com polímeros e eletrólitos têm uso COITentena perfuração de poços de petróleo. A fonnulação e manutenção de suas características é fator essencial para o sucesso de uma operação de perfuração, sobretudo as que se referem à propriedades reológicas e estabilidade fisico-química. Este trabalho propõe um estudo mais detalhado de suas propriedades fisico-químicas levando-se em conta o nível de floculação destas suspensões, que depende de parâmetros como a distribuição das cargas elétricas e tamanho das partículas. Para tanto, foram efetuadas medidas de mobilidade eletroforética (potencial zeta) juntamente com as propriedades reológicas. Estes fluidos apresentam comportamento não-newtoniano, cujo modelo reológico que mais se adequa é o de Herschel-Bulkley. O estudo conjunto das propriedades reológicas e eletrocinéticas visam interpretar o comportamento macroscópico dessas suspensões com base em dados experimentais relacionados com a estrutura e estabilidade das mesmas. São avaliados também o efeito da variação do pH, concentração de poliacrilamida e de NaCI nestas propriedades. São apresentados ainda alguns resultados de medidas de propriedades viscoelásticas destes fluidos / Abstract: Suspensions of clay with polymers and electrolytes have a large use in drilling of petroleum wells. The formulation and maintenance of his characteristics are essencial factor to the sucessful of a drilling operation, mainly that refer to rheological properties and physical-chemistry stabilities. This work proposes more detailer study of his physical-chemistry properties considering the level of floculation of that suspensions, that depends on electrical charge distribution and size of particles. In this way, were accomplish measurements of electrophoretic mobility (zeta potential) and rheological properties. This fluids presents non-newtonian behaviour, and the rheological model that is more appropriate is the Herschel-Bulkley's model. The study in association of rheological and electrokinetic properties have the objective of interpret the macroscopic behaviour of this suspensions supported in experiments relationship between his structure and stability. The effect of pH, amount of polyacrylamide and NaCI, are analyzed in that properties. Some measurements of viscoelastic properties are also introduced. / Mestrado / Mestre em Engenharia de Petróleo

No description available.

The aim of this thesis is to examine the connection between the Riemannhypothesis and the distribution of prime numbers. We first derive theanalytic continuation of the zeta function and prove some of its propertiesusing a functional equation. Results from complex analysis such asJensen’s formula and Hadamard factorization are introduced to facilitatea deeper investigation of the zeros of the zeta function. Subsequently, therelation between these zeros and the asymptotic distribution of primesis rendered explicit: they determine the error term when the prime-counting function π(x) is approximated by the logarithmic integral li(x).We show that this absolute error is O(x exp(−c√log x) ) and that the Riemannhypothesis implies the significantly improved upper bound O(√x log x).

<p> In this study the experiments were designed to measure the geochemical and surface charge (zeta potential) changes with time for two crushed samples of feldspar (Na-fs and K-fs) over the pH range of most natural waters (5 to 9). These experiments show: </p> <p> (a) the importance of adsorption/desorption phenomena in both short-term and long-term feldspar dissolution, and probably for chemical weathering in general; </p> <p> (b) that the generalized curve which characterizes the geochemical data (an initial rapid rise to a peak followed by a decrease to a lower, either constant or later increasing value) is consistent with a consideration of the adsorption/desorption process (i.e., the formation of the double layer) taking place at the feldspar surface and with the simple dissolution of the mineral; </p> <p> (c) that the cation-silica ratios (Na₂O/SiO₂, K₂O/SiO₂, CaO/SiO₂) of the solution compared to those in the original feldspar indicate an initially incongruent dissolution which tends towards congruency during the latter part of the experiments. </p> <p> From information in the Iiterature and the results of these experiments. it may be concluded that: </p> <p> (a) the most important or master variables in chemical weathering are abrasion, minerologic or crystallographic factors such as twinning, exsolution regions, impurities, fractures and grain size, and solution composition and concentration. pH does not appear to be a master variable in most natural waters, especially for long-term weathering, and the chemical composition of the mineral phase is also not a good criterion for predicting weathering behaviour; and </p> <p> (b) the most extreme chemical weathering should occur in a high energy environment, either for physical reasons (i.e., high abrasion due to extreme relief) or for chemical reasons (i.e., high rainfall). </p> / Thesis / Master of Science (MSc)