There has been much effort in new design for transceiver used in mobile communications. The general approach is to combine RF functions with DSP to allow linear modulation techniques and permit flexibility of modulation format and receiver processing. In practice, with the quadrature modulation technique there is always some imbalance between the I- and Q channels of modulator and demodulator. This is mainly due to finite tolerances of capacitor and resistor values used to implement the analog components. The unavoidable imbalance between the I- and Q channels is known to degrade the performance of quadrature communication system. The main concern of this thesis is to propose a new blind scheme and with fast convergence algorithm, such as the inverse QRD-RLS algorithm, to deal with the problem described above for compensation in the transmitter and receiver. First, for the transmitter, the so-called adaptive estimation and compensation with power measurement implemented by the inverse QRD-RLS algorithm is employed. While in the receiver, a new blind adaptive filtering approach of the nonlinear parameters estimation and compensation, along with the power measurement in the receiver, is devised to adaptively compensate for the gain/phase imbalance and DC offsets in a quadrature demodulator. Where the conventional inverse QRD-RLS algorithm is employed for estimating the parameters of compensator, without using any reference signal transmitted from the transmitter. To document the merits of the proposed scheme, computer simulation for the coherent 16-PSK-communication system is carried out. With our proposed method a great improvement for eliminating the effects of the imbalance and offset over the existing techniques has verified. It has rapidly convergence rate and the smaller mean square error in steady state.

Flame based synthesis is a major manufacturing process of commercially valuable nanoparticles for large-scale production. However, this important industrial process has been advanced mostly by trial-and-error based evolutionary studies owing to the fact that it involves tightly coupled multiphysics flow phenomena. For large scale synthesis of nanoparticles, different physical and chemical processes exist, including turbulence, fuel combustion, precursor oxidation, and nanoparticle dynamics exist. A reliable and predictive computational model based on fundamental physics and chemistry can provide tremendous insight. Development of such comprehensive computational models faces challenges as they must provide accurate descriptions not only of the individual physical processes but also of the strongly coupled, nonlinear interactions among them. In this work, a multiscale computational model for flame synthesis of TiO2 nanoparticles in a turbulent flame reactor is presented. The model is based on the large-eddy simulation (LES) methodology and incorporates detailed gas phase combustion and precursor oxidation chemistry as well as a comprehensive nanoparticle evolution model. A flamelet-based model is used to model turbulence-chemistry interactions. In particular, the transformation of TiCl4 to the solid primary nucleating TiO2 nanoparticles is represented us- ing an unsteady kinetic model considering 30 species and 70 reactions in order to accurately describe the critical nanoparticle nucleation process. The evolution of the TiO2 number density function is tracked using the quadrature method of moments (QMOM) for univariate particle number density function and conditional quadrature method of moments (CQMOM) for bivariate density distribution function. For validation purposes, the detailed computational model is compared against experimental data obtained from a canonical flame- based titania synthesis configuration, and reasonable agreement is obtained. / text

Nowadays, demands for fully integrated and miniaturized RFIC (Radio Frequency Integrated Circuits) have increased in wireless microwave communication system. Passive components such as coupler, divider and filters are always fabricated in outside of ICs due to their bulky sizes, which have been a great barrier to a realization of a fully integrated design. To solve this problem, miniaturization of passive components is one of the big issues at the present time. This paper shows the development of two important microwave passive components, quadrature hybrid and rat-race couplers for LTE lower (698 -960 MHz) and higher (1.71 - 2.70 GHz) frequency bands, which are obtained by replacing quarter-wave (λ/4) transmission line of a conventional coupler by their equivalent coupled line, resulting in significant size reduction. The miniaturized quadrature and rat race couplers are designed and fabricated with a Rogers 4360 substrate as a platform in producing significantly reduction. The design is validated by electromagnetic simulation and measurement. The size of the implemented quadrature hybrid coupler is 30 × 26.8 mm^2 and 14.9 × 12.5 mm^2, which are 82.60 % and 69.03% compared to the conventional couplers for lower and higher frequency band respectively. And, 55.5 × 27.9 mm^2 and 19.2 × 14.8 mm^2 for rat race coupler, which are 79.69 % and 62.35 % compared to the conventional coupler for lower and higher frequency band, respectively. Also, the reflection coefficient and the isolation are as good as conventional one and coupling procedure is similar or better than it.

In this thesis, Finite Volume Weighted Essentially Non-Oscillatory (FV-WENO) codes for one and two-dimensional discretised Euler equations are developed. The construction and application of the FV-WENO scheme and codes will be described. Also the effects of the grid coefficients as well as the effect of the Gaussian Quadrature on the solution have been tested and discussed. WENO schemes are high order accurate schemes designed for problems with piecewise smooth solutions containing discontinuities. The key idea lies at the high approximation level, where a convex combination of all the candidate stencils is used with certain weights. Those weights are used to eliminate the stencils, which contain discontinuity. WENO schemes have been quite successful in applications, especially for problems containing both shocks and complicated smooth solution structures. The applications tested in this thesis are the Diverging Nozzle, Shock Vortex Interaction, Supersonic Channel Flow, Flow over Bump, and supersonic Staggered Wedge Cascade. The numerical solutions for the diverging nozzle and the supersonic channel flow are compared with the analytical solutions. The results for the shock vortex interaction are compared with the Roe scheme results. The results for the bump flow and the supersonic staggered cascade are compared with results from literature.

Made available in DSpace on 2014-06-11T19:26:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-02-24Bitstream added on 2014-06-13T18:30:55Z : No. of bitstreams: 1 veronese_do_me_sjrp.pdf: 430710 bytes, checksum: 769cae2276392992bc8f2c9eaf54fd4e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Dentre as diversas fórmulas de quadratura interpolatórias estão aquelas que utilizam em sua construção as propriedades dos polinômios ortogonais Pn, ou ainda dos polinômios similares Bn. Consideramos, aqui, fþormulas de quadratura envolvendo polinôomios em x da forma .n(x, .) = Pn-1(.)Pn(x) - Pn(.)Pn-1(x), e da forma Gn(x, u) = Bn-1(u)Bn(x) - Bn(u)Bn-1(x). Abordamos ainda certas fþormulas de quadratura que visam aproximar a integral de um produto de duas funções k e f sendo k Lebesgue integrþavel e f Riemann integrþavel. O principal objetivo deste trabalho þe analisar propriedades das fþormulas de quadratura utilizando-se .n e obter propriedades anþalogas para o caso onde utiliza-se Gn, bem como estudar o erro e as propriedades de convergência das fórmulas envolvendo k e f. Propriedades dos pesos das fórmulas de quadratura nos diversos casos são analisadas, a convergência das fórmulas associadas a k e f são estudadas mediante determinadas escolhas de pontos. / Among the many well known quadrature formulas one finds those interesting interpolatory quadrature formulas that take advantage of the properties of orthogonal polynomials Pn or similar polynomials Bn. Here, we consider the interpolatory quadrature rules based on the zeros of the polynomials øn(x, î) = Pn.1(î)Pn(x).Pn(î)Pn.1(x), and Gn(x, u) = Bn.1(u)Bn(x) . Bn(u)Bn.1(x) where î and u are arbitrary parameters. One of the objective of this dissertation is to study some of the known properties of quadrature rules based on øn(x, î) and consider the analogous properties of the quadrature rules based on Gn(x, u).We also look at the convergence properties of those quadrature rules that serve to approximate integrals of the product of functions k and f, where k is a Lebesgue integrable function and f needs to be a Riemann integrable function.

It is widely accepted that, for many buckling problems of plates and shells in the plastic range, the flow theory of plasticity either fails to predict buckling or significantly overestimates buckling stresses and strains, while the deformation theory, which fails to capture important aspects of the underlying physics of plastic deformation, provides results that are more in line with experimental findings and is therefore generally recommended for use in practical applications. This thesis aims to contribute further understanding of the reasons behind the seeming differences between the predictions provided by these two theories, and therefore provide some explanation of this so-called ‘plastic buckling paradox’. The study focuses on circular cylindrical shells subjected to either axial compression or non-proportional loading, the latter consisting of combined axial tensile stress and increasing external pressure. In these two cases, geometrically nonlinear finite-element (FE) analyses for perfect and imperfect cylinders are conducted using both the flow and the deformation theories of plasticity, and the numerical results are compared with data from widely cited physical tests and with analytical results. The plastic buckling pressures for cylinders subjected to non-proportional loading, with various combinations of boundary conditions, tensile stresses, material properties and cylinder’s geometries, are also obtained with the help of the differential quadrature method (DQM). These results are compared with those obtained using the code BOSOR5 and with nonlinear FE results obtained using both the flow and deformation theories of plasticity. It is found that, contrary to common belief, by using a geometrically nonlinear FE formulation with carefully determined and validated constitutive laws, very good agreement between numerical and test results can be obtained in the case of the physically more sound flow theory of plasticity. The reason for the ‘plastic buckling paradox’ appears to be the over-constrained kinematics assumed in many analytical and numerical treatments, such as BOSOR5 and NAPAS, whereby a harmonic buckling shape in the circumferential direction is prescribed.

Les applications de variation de vitesse des machines alternatives mettent en oeuvre des réseaux Modulés en Largeur d’Impulsion (MLI). La commande de ces machines nécessite la connaissance de données comme la vitesse ou la position du rotor. La transmission des données par Courant Porteur en Ligne (CPL) sur le réseau d’énergie permet de simplifier l’installation et l’entretien du système, d’augmenter sa fiabilité et de réduire son coût. Les modems CPL actuellement disponibles ne sont pas compatibles avec les applications de variation de vitesse. Le bruit (tension MLI) de type impulsionnel ainsi que l’atténuation du signal de communication à travers les câbles d’énergie sont les deux principaux obstacles au déploiement du CPL sur les réseaux MLI. Le développement d’une solution spécifique est donc nécessaire pour pouvoir utiliser le CPL. A partir du banc d’essai, le moteur, les câbles triphasés de longueurs de 10, 60 et 110 mètres et l’onduleur ont été modélisés et une fonction de transfert du canal est obtenue et validée par des mesures., La tension MLI a été mesurée et caractérisée. À partir de ces données, un calcul du rapport canal à bruit (CNR) a permis d’identifier les fréquences centrales optimales. Deux paires de coupleurs (Rx, Tx) sont réalisées autour de ces fréquences avec une bande passante de 10MHz. Un simulateur de communication intégrant le modèle du canal et du bruit a été développé. Le banc d’essai a été enrichi avec un système de modulation/démodulation QAM complet. Les résultats de simulation, en termes de puissance, débit et TEB, sont ensuite comparés aux résultats obtenus par le banc d’essai. / Pulse Width Modulated (PWM) networks are used in adjustable-speed drive applications. Data like, speed and rotor position, coming from sensors on the motor, are necessary for the control. Other data like, temperature and current value are important for monitoring purposes. Using Power Line Communication (PLC) techniques to transfer data from those sensors to the control has some numerous benefits. The most obvious are, simplified installation and maintenance, increase of reliability and reduction of cost. Unfortunately, PLC modems used in low-voltage sinusoidal network are not compatible with this type of application. In fact, the PLC signal suffers from power cables attenuation. In addition, the PWM voltage can generate high level noise in the bandwidth used by traditional PLC modems. Therefore, a specific PLC solution is needed in this type of applications. To find an optimized solution, the motor, the inverter as well as the cables (10, 60 and 110 meters) are modeled by a chain matrix. The transfer function calculated from the model is verified by measurements. Afterward, the PWM voltage is measured and characterized. Using the transfer function in addition to the PWM measurements, the Channel to Noise Ratio (CNR) is calculated. The CNR provides the best two center frequencies for PLC couplers. For each frequency, a couple of couplers (Tx, Rx) of 10MHz width is made. A communication simulator is made using channel model and noise (PWM) measurements. In addition, the test bench is upgraded with a QAM modem. A wide comparison is made between results (output power, bit rate and BER) obtained from the test bench and from simulations.

A distribuição de massa molar (DMM) e seus parâmetros são de fundamental importância na caracterização dos polímeros. Por este motivo, o desenvolvimento de técnicas que permitam a determinação da DMM de forma mais rápida e a menor custo é de grande importância prática. Os principais objetivos deste trabalho foram a implementação de alguns dos modelos baseados da teoria da reptação dupla propostos na literatura para descrever o mecanismo de relaxação das cadeias poliméricas, a avaliação dessas implementações e a análise de dois passos fundamentais na obtenção da DMM a partir de dados reológicos que são a metodologia de cálculo do espectro de relaxação baseado no modelo de Maxwell e a estratégia para a avaliação numérica das integrais que aparecem nos modelos de relaxação. Foi resolvido o problema denominado problema inverso, ou seja, a determinação da DMM a partir de dados reológicos usando um modelo de relaxação especificado e uma função de distribuição imposta. Foi usada a função Exponencial Generalizada (GEX) para representar a probabilidade de distribuição, sendo consideradas duas abordagens: i) cálculo explícito do espectro de relaxação e ii) aproximações paramétricas de Schwarzl, que evitam a necessidade do cálculo explícito do espectro de relaxação. A metodologia de determinação da DMM foi aplicada para amostras de polietileno e foram estimadas distribuições com boa representação dos dados experimentais do GPC, ao considerarem-se amostras com polidispersões inferiores a 10. Com relação a metodologia de cálculo do espectro de relaxação, foi realizado um estudo comparativo da aplicação de espectros de relaxação discreto e contínuo, com o objetivo de estabelecer critérios para especificação do número ótimo de modos de Maxwell a serem considerados. Ao efetuar-se a comparação entre as técnicas, verificou-se o espectro discreto apresenta como um sistema melhor condicionado, permitindo assim obter maior confiabilidade dos parâmetros estimados. Também é proposta uma modificação da metodologia de determinação da DMM, em que é aplicada a quadratura de Gauss-Hermite para a resolução numérica da integral dos modelos de relaxação. / The molecular weight distribution (MWD) and its parameters are of the fundamental importance in the characterization of polymers. Therefore, the development of techniques for faster and less time consuming determination of the MWD is of great practical relevance. The goals of this work were the implementation of some of the relaxation models from double reptation theory proposed in the literature, the evaluation of these implementations and the analysis of two key points in the recovery of the MWD from rheological data which are the methodology for calculation of the relaxation spectrum based on the Maxwell model and the numeric strategy for the evaluation of the integrals appearing in the relaxation models. The inverse problem, i.e., the determination of the MWD from rheological data using a specified relaxation model and an imposed distribution function, was solved. In the analysis of the inverse problem, the Generalized Exponential (GEX) was used as distribution function and two approaches were considered: i) explicit calculation of the relaxation spectrum and ii) use of the parametric method proposed by Schwarzl to avoid the explicit calculation of the relaxation spectrum. In the test of commercial samples of polyethylene with polidispersity less than 10, the application of this methodology led to MWD curves which provided good fit of the experimental SEC data. Regarding the methodology for calculation of the relaxation spectrum, a comparison between the performance of discrete and continuous relaxation spectrum was performed and some possible a criteria to determine the appropriate number of relaxation modes of Maxwell to be used were evaluated. It was found that the technique of discrete spectrum leads to better conditioned systems and, consequently, greater reliability of the estimated parameters. With relation to the numeric strategy for the evaluation of the integrals appearing in the relaxation models, the use of Gauss-Hermite quadrature using a new change of variables was proposed.

A distribuição de massa molar (DMM) e seus parâmetros são de fundamental importância na caracterização dos polímeros. Por este motivo, o desenvolvimento de técnicas que permitam a determinação da DMM de forma mais rápida e a menor custo é de grande importância prática. Os principais objetivos deste trabalho foram a implementação de alguns dos modelos baseados da teoria da reptação dupla propostos na literatura para descrever o mecanismo de relaxação das cadeias poliméricas, a avaliação dessas implementações e a análise de dois passos fundamentais na obtenção da DMM a partir de dados reológicos que são a metodologia de cálculo do espectro de relaxação baseado no modelo de Maxwell e a estratégia para a avaliação numérica das integrais que aparecem nos modelos de relaxação. Foi resolvido o problema denominado problema inverso, ou seja, a determinação da DMM a partir de dados reológicos usando um modelo de relaxação especificado e uma função de distribuição imposta. Foi usada a função Exponencial Generalizada (GEX) para representar a probabilidade de distribuição, sendo consideradas duas abordagens: i) cálculo explícito do espectro de relaxação e ii) aproximações paramétricas de Schwarzl, que evitam a necessidade do cálculo explícito do espectro de relaxação. A metodologia de determinação da DMM foi aplicada para amostras de polietileno e foram estimadas distribuições com boa representação dos dados experimentais do GPC, ao considerarem-se amostras com polidispersões inferiores a 10. Com relação a metodologia de cálculo do espectro de relaxação, foi realizado um estudo comparativo da aplicação de espectros de relaxação discreto e contínuo, com o objetivo de estabelecer critérios para especificação do número ótimo de modos de Maxwell a serem considerados. Ao efetuar-se a comparação entre as técnicas, verificou-se o espectro discreto apresenta como um sistema melhor condicionado, permitindo assim obter maior confiabilidade dos parâmetros estimados. Também é proposta uma modificação da metodologia de determinação da DMM, em que é aplicada a quadratura de Gauss-Hermite para a resolução numérica da integral dos modelos de relaxação. / The molecular weight distribution (MWD) and its parameters are of the fundamental importance in the characterization of polymers. Therefore, the development of techniques for faster and less time consuming determination of the MWD is of great practical relevance. The goals of this work were the implementation of some of the relaxation models from double reptation theory proposed in the literature, the evaluation of these implementations and the analysis of two key points in the recovery of the MWD from rheological data which are the methodology for calculation of the relaxation spectrum based on the Maxwell model and the numeric strategy for the evaluation of the integrals appearing in the relaxation models. The inverse problem, i.e., the determination of the MWD from rheological data using a specified relaxation model and an imposed distribution function, was solved. In the analysis of the inverse problem, the Generalized Exponential (GEX) was used as distribution function and two approaches were considered: i) explicit calculation of the relaxation spectrum and ii) use of the parametric method proposed by Schwarzl to avoid the explicit calculation of the relaxation spectrum. In the test of commercial samples of polyethylene with polidispersity less than 10, the application of this methodology led to MWD curves which provided good fit of the experimental SEC data. Regarding the methodology for calculation of the relaxation spectrum, a comparison between the performance of discrete and continuous relaxation spectrum was performed and some possible a criteria to determine the appropriate number of relaxation modes of Maxwell to be used were evaluated. It was found that the technique of discrete spectrum leads to better conditioned systems and, consequently, greater reliability of the estimated parameters. With relation to the numeric strategy for the evaluation of the integrals appearing in the relaxation models, the use of Gauss-Hermite quadrature using a new change of variables was proposed.

In the first part of this thesis, we prove two density theorems for quadrature domains in Cn ,n≥2. It is shown that quadrature domains are dense in the class of all product domains of the form D×Ωwhere D⊂Cn−1 is a smoothly bounded pseudoconvex domain satisfying Bell’s Condition R and Ω⊂Cis a smoothly bounded domain. It is also shown that quadrature domains are dense in the class of all smoothly bounded complete Hartogs domains in C2. In the second part of this thesis, we study the behaviour of the critical points of the Green’s function when a sequence of domains Dk⊂Rn con-verges to a limiting domain Din the C∞-topology. It is shown that the limit-ing set of the critical points of the Green’s functions Gkfor domains Dk⊂Care the zeroes of the Bergman kernel of D. This generalizes a result of Solynin and Gustafsson, Sebbar.