Η παρούσα διατριβή εστιάζεται σε οπτικά τηλεπικοινωνιακά συστήματα με σύμφωνο δέκτη, τετραδική διαμόρφωση φάσης και πολύπλεξη κατά πόλωση. Το κυριότερο πλεονέκτημα αυτών των συστημάτων σε σύγκριση με τα συμβατικά οπτικά τηλεπικοινωνιακά συστήματα με δέκτες άμεσης φώρασης είναι οι αυξημένες δυνατότητες ψηφιακής επεξεργασίας σήματος στο δέκτη, που καθιστά εφικτή την εξίσωση των φαινομένων διάδοσης και την αποπολύπλεξη πόλωσης με ηλεκτρονικά μέσα. Μελετώνται διατάξεις ηλεκτρονικής επεξεργασίας σήματος. Η μελέτη διεξάγεται με χρήση προσομοίωσης με τη βοήθεια ηλεκτρονικού υπολογιστή. Προτείνεται η χρήση δύο πρωτότυπων μεθόδων αποπολύπλεξης σημάτων πολυπλεγμένων κατά πόλωση, με πλεονεκτήματα ως προς την απόδοση, την αξιοπιστία και την ταχύτητα σύγκλισης σε σύγκριση με τις μεθόδους που έχουν προταθεί στη βιβλιογραφία Στη συνέχεια μελετάται η απόδοση των ηλεκτρονικών εξισωτών ελαχίστου μέσου τετραγώνου (least-mean square) και σταθερής περιβάλλουσας (constant modulus algorithm) στην εξίσωση της χρωματικής διασποράς και της διασποράς τρόπων πόλωσης, τόσο μεμονωμένα, όσο και από κοινού. Στη μελέτη μας συμπεριλαμβάνουμε το θόρυβο φάσης και την ενδιάμεση συχνότητα, αίροντας αντίστοιχες απλοποιήσεις που συνήθως γίνονται στη βιβλιογραφία. Ακολούθως αναφερόμαστε στο πρόβλημα του εκφυλισμού του πίνακα συντελεστών των εξισωτών ελαχίστου μέσου τετραγώνου και σταθερής περιβάλλουσας παρουσία έντονης διεξασθένησης. O πίνακας συντελεστών στον οποίο έχει συγκλίνει ο εξισωτής ονομάζεται εκφυλισμένος όταν παράγεται η ίδια απεσταλμένη ακολουθία συμβόλων και στις δύο εξόδους του εξισωτή. Προτείνουμε τη χρήση του πολυχρηστικού εξισωτή σταθερής περιβάλλουσας (multiuser constant modulus algorithm equalizer). Η λύση που προτείνεται έχει πλεονεκτήματα αξιοπιστίας και απλότητας σε σχέση με αντίστοιχες προτάσεις στη βιβλιογραφία, και αποδεικνύεται η άριστη απόδοσή της. Στη συνέχεια, γίνεται αναφορά στο φαινόμενο της ανισοσταθμίας ορθογωνιότητας που παρατηρείται στα οπτικά συστήματα με σύμφωνους δέκτες και αποτελεί ένα φαινόμενο το οποίο, κατά κανόνα, παραβλέπεται στις μελέτες της βιβλιογραφίας και αποδεικνύεται το ότι οι συμβατικοί ηλεκτρονικοί εξισωτές δεν μπορούν να το αντιμετωπίσουν. Τέλος, παραθέτουμε αποτελέσματα από την επεξεργασία πραγματικών πειραματικών δεδομένων, για την επαλήθευση των συμπερασμάτων που προέκυψαν θεωρητικά. / This PhD dissertation focuses on optical communication systems utilizing coherent receiver, quadrature phase modulation and polarization multiplexing. Their main advantage compared to conventional systems is the ability to perform extended digital signal processing, in order to compensate for transmission effects and to successfully demultiplex polarization multiplexed signals. We study such DSP modules with the help of computer simulations. We propose two novel polarization demultiplexing algorithms, with advantages in performance reliability and convergence speed compared to conventional methods. One of the two methods utilizes training procedure, an approach not yet studied enough in the literature. Next, we study the performance of least mean square and constant modulus algorithm equalizers in mitigating chromatic dispersion and polarization mode dispersion, both separately and in combination. We include in our study phase noise and intermediate frequency offset, without the simplifications usually found in the literature. Next, we address the subject of equalizer degeneration, which describes the phenomenon when both equalizer outputs transmit one of the two polarization multiplexed signals. We propose the use of multi-user constant modulus algorithm, which is an enhanced version of the conventional constant modulus algorithm. We prove that our solution has excellent performance as well as reliability and simplicity advantages compared to other methods. Next, we prove that quadrature imbalance is a ubiquitous phenomenon that cannot be addressed with conventional electronic equalizers and should not be omitted as is often the case. Finally, we present results derived from the application of some of the proposed algorithms on real experimental data, and prove the consistency of the theoretical derived results.

Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-04-23T18:24:48Z No. of bitstreams: 1 Dissertacao - Leonardo Assis Costa.pdf: 5179729 bytes, checksum: 817fc041b92e51f18cdd3caef2d8bc9d (MD5) / Approved for entry into archive by Rodrigo Meirelles(rodrigomei@ufba.br) on 2013-05-16T18:06:59Z (GMT) No. of bitstreams: 1 Dissertacao - Leonardo Assis Costa.pdf: 5179729 bytes, checksum: 817fc041b92e51f18cdd3caef2d8bc9d (MD5) / Made available in DSpace on 2013-05-16T18:07:00Z (GMT). No. of bitstreams: 1 Dissertacao - Leonardo Assis Costa.pdf: 5179729 bytes, checksum: 817fc041b92e51f18cdd3caef2d8bc9d (MD5) Previous issue date: 2008 / O manchamento dental pelo cigarro constitui uma das principais queixas dos pacientes fumantes, entretanto a ação do tabaco sobre materiais restauradores estéticos tem sido pouco relatada. Este estudo teve como objetivo avaliar o efeito da fumaça de cigarro, na cor de restaurações em resina composta realizadas com quatro diferentes sistemas adesivos (dois convencionais e dois autocondicionantes). Quarenta terceiros molares humanos foram seccionados no sentido mesio-distal e, posteriormente, preparos circulares foram realizados na junção amelodentinária, das suas respectivas faces vestibular e lingual, com 3mm de diâmetro e 1,5mm de profundidade. Os dentes foram divididos em oito grupos (n=10), de acordo a exposição ou não à fumaça de cigarro e de acordo com o sistema adesivo utilizado (Scotchbond Multi-Uso Plus [SBMP], Adper Single Bond 2 [SB], Clearfil SE Bond [SE], Adper Prompt [AP]), e restaurados com a resina composta (Filtek Z350). Os grupos experimentais foram expostos à fumaça de 1.200 cigarros, 10 cigarros, duas vezes ao dia, por um período de 10 minutos, durante 60 dias consecutivos. As alterações cromáticas foram avaliadas através da análise de fotografias digitais nos tempos: T0 (inicial); T1 (após 30 dias de exposição ao cigarro) e T2 (após 60 dias de exposição ao cigarro). As imagens foram avaliadas com o auxílio do software Adobe Photoshop CS3, considerando os parâmetros de cor do sistema CIE L*a*b* e da diferença total de cor (ΔE’). Os valores médios de ΔE’ e DP para os grupos expostos à fumaça do cigarro ao final do experimento foram: SMPB 23,28 (3,24), SB 27,60 (5,06), SE 26,65 (5,08), AP 27,30 (5,30) (ANOVA/Tukey - p < 0,05). Com base nos resultados pode-se concluir a fumaça do cigarro causou alteração na cor de restaurações em resina composta. Os espécimes restaurados utilizando o SBMP e o SB apresentaram os menores valores de ΔE’. Os espécimes não expostos à fumaça do cigarro e armazenados em água destilada não apresentaram alteração significante nos valores de ΔE’. / Salvador

Made available in DSpace on 2014-06-11T19:27:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-01-17Bitstream added on 2014-06-13T20:17:29Z : No. of bitstreams: 1 lozano_d_me_sjrp.pdf: 1183878 bytes, checksum: 4a6bb33915f7d1702bf0df3808789aa1 (MD5) / Secretaria de Educação do Estado de São Paulo / O objetivo desse trabalho é apresentar o problema de coloração em grafos sob diferentes perspectivas. Caracterizamos o polinômio cromático de um grafo e enunciamos algumas de suas propriedades. Apresentamos duas formulações matemáticas para o problema de coloração de vértices e um método de solução para cada formulação. Apresentamos e discutimos propostas de atividades para o desenvolvimento de uma Oficina de Coloração para alunos do Ensino Médio e Fundamental. / In this work the graph coloring problem was presented under di erent perspectives. We define the chromatic polynomials of a graph and describe some of its properties. Furthermore, two solution methods for the vertex coloring problem, through integer programming formulation, has been presented. We propose and discuss some activities for the development of a Workshop for students of secondary school.

Made available in DSpace on 2016-03-15T19:36:30Z (GMT). No. of bitstreams: 1 Ana Paula Momose Guimaraes.pdf: 1662498 bytes, checksum: 4bf2c8bc75da4d6140d8dc0e43845138 (MD5) Previous issue date: 2011-08-31 / Fundo Mackenzie de Pesquisa / This work analyzes the influence of the inorganic pigment of iron oxide in the addition of mortar and concrete of Portland cement and what their improvements within this incorporation . It is situated in recent years, advances in the types, varieties and classes of resistance of cement has enabled significant improvements in physical and chemical properties of concrete mainly mechanical resistance and durability, allied of course the most common use of chemical additives concrete. In this context our study is to analyze the influence that the pigments can bring improvement not only in its aesthetic aspect but also on their mechanical properties. Contextualizing generally what types of cements, aggregates and additives that has been available on the market today, what are the main applications for cement and chooses the best features that best applications the concrete chromatic .A choice of inorganic pigment iron oxide was deliberately chosen by be the pigment of increased consumption and use worldwide in construction and due to its high thermal stability, durability, and especially for its low cost. Thus seek to study and try to better understand the complex and heterogeneous microstructure of colored concrete and what improvements can be induced in the incorporation of the pigment mass, where they were investigating whether the pigment can be incorporated in the voids between these aggregates present the complex structure of interfaces cement hydration. Assembled an experimental program consists of six levels of pigment (0%, 3%, 5%, 7%, 9% e 12%) aimed to test and verify the changes of its workability, the mechanical compression changes the workability, mechanical strength and porosity investigated through the ultrasound and microscopy. The aim is thus possible that the use of colored concrete need not only sandbank on floors (interlocking blocks, industrial flooring, etc.) or pre molded pieces (vases, cement plates, tiles, blocks, etc.) but also seeks to expand its application to large structures, but for this to happen we are seeking a better understanding of its characteristics and nuances compared to conventional concrete. / Este trabalho busca analisar a influência do pigmento inorgânico de óxido de ferro na adição da argamassa e no concreto de cimento portland e quais as suas melhorias dentro desta incorporação. Cabe situar que nos últimos anos, o avanço nos tipos e classes de resistências do cimento tem possibilitado grandes melhorias nas propriedades físicas e químicas do concreto principalmente a resistência mecânica e sua durabilidade, aliado ao uso mais comum de aditivos químicos específicos para o concreto. Neste contexto o estudo busca analisar a influência que os pigmentos podem trazer de melhoria não só no seu aspecto estético, mas quem sabe melhorar na resistência mecânica. Contextualizando de uma maneira geral quais os tipos de cimentos, agregados e aditivos que existe hoje disponível no mercado brasileiro, quais as principais aplicações para escolha do melhor cimento e características que melhor se aplica no concreto cromático. A escolha do pigmento inorgânico de óxido de ferro foi escolhida propositadamente por ser o pigmento de maior consumo e uso mundial na construção civil. Também a sua alta estabilidade térmica, durabilidade e dispersabilidade. Buscam-se assim estudar e buscar compreender a microestrutura complexa e heterogênea do concreto colorido e quais influências será provocado na incorporação do pigmento na massa, onde investigam se o pigmento acopla nos vazios presentes entre os agregados e a estrutura da hidratação do cimento, ou até mesmo quem sabe melhorar, na própria estrutura da hidratação e se isto pode gerar melhor empacotamento teórico. Montado um programa experimental composto por 6 (seis) teores de pigmento (0%, 3%, 5%, 7%, 9% e 12%) visando ensaiar, comparar e verificar as mudanças na trabalhabilidade, na resistência mecânica a compressão e verificar a variação de descontinuidade interna no concreto pigmentado através dos ensaios de ultrassom. Por microscopia, também será buscado verificar quais os locais que se alojam o pigmento na estrutura no compósito cimentício. Pretendem-se desta maneira verificar se poderão ampliar com mais propriedade o uso do concreto colorido na sua aplicação não apenas em pisos (blocos intertravados, pisos industriais, concreto estampado decorativo, etc.) e em peças pré-moldadas (vasos, placas cimentícias, telhas, blocos, etc.), mas também sua aplicação em grandes estruturas estuda-se mais e melhor as características do concreto pigmentado e as nuances frente ao concreto convencional.

Made available in DSpace on 2016-08-18T18:19:30Z (GMT). No. of bitstreams: 1 Dissertacao Girlane.pdf: 2233662 bytes, checksum: e187d35550c694d6e69d8bc6b2ca20db (MD5) Previous issue date: 2011-09-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Raman scattering phenomena has far been widely used as an experimental methodology for probing materials properties. In the last decade, the combination of microscopy and spectroscopy aspects has been largely used in the study of materials in low dimensions, especially carbon nanotubes and graphene. Graphene is a two-dimensional material that has one hexagonal structure. Due to its excellent crystalline quality, this material has shown great prospects of strategic applications in the near future. The majority of the studies reported on graphene are carried out by using confocal microscopes, which relies on the longitudinal chromatic aberration. This optical effect is related to intrinsic limitation of any lens to focus light with different wavelength at the same focal plane. In this work, we examine the effect of longitudinal chromatic aberration and also the effect of irradiance on the Raman spectra of graphene. Consistent with the results of literature, we found that the intensity of the Raman signal for the G mode increases linearly with the number of layers, up to the limit of six layers identified in our samples. We also found a strong dependence of the Raman intensity with longitudinal chromatic aberration. Owing to this effect, the intensity of the G peak was underestimated in about 20%, while the intensity of G peak appeared 56% below the real value. Measurement performed to confirm the effect of longitudinal chromatic aberration showed an aberration of 1,8 μm/eV for Raman scattering and 2,0 μm/eV by using pure reflectometry. Measurements in graphene with defects revealed a strong dependence of peak frequency with focal position and laser power as well. Changes of 6 cm-1 in G' mode was observed for laser power between 44 e 175 μW. / A microscopia Raman é uma das técnicas experimentais mais versáteis e tem sido muito utilizada no estudo das propriedades físicas de materiais. A microscopia confocal em combinação com a espectroscopia Raman tem levado a obtenção de imagens de estruturas em escala nanométrica. Estas ferramentas conjugadas têm sido amplamente utilizadas no estudo de propriedades de materiais em baixas dimensões, como nanotubos de carbono e grafeno. O grafeno é um material bidimensional que possui uma estrutura hexagonal. Devido à sua excelente qualidade cristalina, esse material tem apresentado grandes perspectivas de aplicações estratégicas no futuro próximo. Neste trabalho foram discutidos os efeitos da aberração cromática longitudinal e o efeito da irradiância sobre espectros Raman do grafeno obtidos por um microscópio Raman confocal. Consistente com os resultados da literatura, a intensidade do sinal Raman para o modo G aumentou linearmente com o número de camadas, até o limite de 6 camadas identificadas nas nossas amostras. Os resultados obtidos mostraram forte dependência da intensidade do sinal com a aberração cromática longitudinal. Por causa deste efeito, a intensidade do pico G foi subavaliada em cerca de 20%, enquanto a intensidade do pico G foi subavaliada em aproximadamente 56%. Medidas realizadas para confirmar o efeito da aberração cromática longitudinal mostraram uma aberração de 1,8 μm/eV para o espalhamento Raman e 2,0 μm/eV para o espalhamento Rayleigh. Medidas em grafeno com defeitos revelaram a grande dependência na posição dos picos com posição focal ou com a potência do laser. Mudanças de 6 cm-1 no modo G foram observadas para potências entre 44 e 175 μW.

In Darwinian evolution, a living population evolves when it is exposed to the selection pressures of a new biological medium. Analogously, in my chromatic evolution a chord "evolves" when it is exposed to a new chromatic medium, forcing it to adapt and harmonically modify its pitch content. This is a process by which a diatonic, consonant chord is progressively transformed into a chromatic substitute, over a span of several similar works, without losing or modifying the chord’s resolution tendencies, harmonic function, or formal location. From a Schenkerian perspective—and using Felix Mendelssohn’s Songs without Words as my corpus study—I will demonstrate how the pre-recapitulatory dominant (the root-position dominant that conventionally precedes the recapitulation) progressively evolves into a highly chromatic substitute: the dominant of the mediant.

Every graph G contains a minimum vertex-coloring with the property that at least one color class of the coloring is a maximal independent set (equivalently, a dominating set) in G. Among all such minimum vertex-colorings of the vertices of G, a coloring with the maximum number of color classes that are dominating sets in G is called a dominating-χ-coloring of G. The number of color classes that are dominating sets in a dominating-χ-coloring of G is defined to be the dominating-χ-color number of G. In this paper, we continue to investigate the dominating-χ-color number of a graph first defined and studied in [1].

A star edge coloring is any edge coloring which is both proper and contains no cycles or path of length four which are bicolored, and the star chromatic index of a graph is the smallest number of colors for which that graph can be star edge colored. Star edge coloring is a relatively new field in graph theory, and very little is known regarding upper bounds of the star chromatic index of most graph types, one of these families being multipartite graphs. We investigate a method for obtaining upper bounds on the star chromatic index of complete multipartite graphs. The basic idea is to decompose such graphs into smaller complete bipartite graphs and applying known upper bounds for such graphs.This method has also been implemented and we present a hypothesis based on simulations.

No description available.

Coherent detection employing multilevel modulation format has become one of the most promising technologies for next generation high speed transmission system due to the high power and spectral efficiencies. With the powerful digital signal processing (DSP), coherent optical receivers allow the significant equalization of chromatic dispersion (CD), polarization mode dispersion (PMD), phase noise (PN) and nonlinear effects in the electrical domain. Recently, the realizations of these DSP algorithms for mitigating the channel distortions in the transmission system are the most attractive investigations.  The CD equalization can be performed by the digital filters developed in the time and the frequency domain, which can suppress the fiber dispersion effectively. The PMD compensation is usually performed in the time domain with the adaptive least mean square (LMS) and constant modulus algorithms (CMA) equalization. Feed-forward and feed-back carrier phase estimation algorithms are employed to mitigate the phase noise from the transmitter and local oscillator lasers. The fiber nonlinearities are compensated by using the digital backward propagation methods based on solving the nolinear Schrodinger (NLS) equation and the Manakov equation.  In this dissertation, we present a comparative analysis of three digital filters for chromatic dispersion compensation, an analytical evaluation of carrier phase estimation with digital equalization enhanced phase noise and a brief discussion for PMD adaptive equalization. To implement these investigations, a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying (NRZ-PDM-QPSK) coherent transmission system is realized in the VPI simulation platform. With the coherent transmission system, these CD equalizers have been compared by evaluating their applicability for different fiber lengths, their usability for dispersion perturbations and their computational complexity. Meanwhile, the bit-error-rate (BER) floor in carrier phase estimation using a one-tap normalized LMS filter is evaluated analytically, and the numerical results are compared to a differential QPSK detection system. / QC 20110629