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CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / Os aÃos inoxidÃveis superduplex sÃo ligas com boa resistÃncia mecÃnica e resistÃncia à corrosÃo, que vÃm sido utilizadas em substituiÃÃo aos aÃos inoxidÃveis austenÃticos convencionais, sendo muito utilizados na indÃstria do petrÃleo. No entanto, o efeito dos ciclos tÃrmicos de soldagem pode ser prejudicial Ãs propriedades destas ligas, atravÃs da alteraÃÃo no balanÃo microestrutural ferrita/austenita e da precipitaÃÃo de fases intermetÃlicas, exigindo uma criteriosa seleÃÃo dos parÃmetros de soldagem. Este problema tende a ser crÃtico na soldagem multipasse, onde hà a imposiÃÃo de vÃrios ciclos tÃrmicos. Desta forma, este trabalho tem como objetivo estudar o efeito dos parÃmetros de soldagem sobre as transformaÃÃes microestruturais e a resistÃncia à corrosÃo na soldagem multipasse do aÃo inoxidÃvel superduplex UNS S32750 pelo processo MIG/MAG. A fim de atingir este objetivo, os seguintes fatores de controle, com seus nÃveis, foram estudados: energia de soldagem (0,6 kJ/mm, 1,0 kJ/mm e 1,8 kJ/mm), gÃs de proteÃÃo (98%Ar + 2%CO2 e 60%Ar + 38%He + 2%CO2) e o formato de onda da corrente (contÃnua e pulsada). As soldagens foram realizadas em juntas com 22 mm de espessura, com geometria em âmeio Vâ e Ãngulo de 45 em uma bancada robotizada. Como planejamento experimental, foi adotado o fatorial fracional com nÃveis mistos, resultando em oito juntas soldadas. Foi realizada uma caracterizaÃÃo microestrutural das regiÃes da Zona Fundida (ZF) e Zona Afetada pelo Calor (ZAC) pelas de Microscopia Ãtica (MO) e Microscopia EletrÃnica de Varredura (MEV). Como caracterÃsticas de resposta, avaliou-se o teor mÃdio de ferrita e o espaÃamento entre os grÃos de austenita (ambos por anÃlise de imagens), a composiÃÃo quÃmica das fases ferrita e austenita (por Espectroscopia de Energia Dispersiva de Raios X â EDS) e a resistÃncia à corrosÃo (pelas tÃcnicas eletroquÃmicas de polarizaÃÃo potenciodinÃmica e espectroscopia de impedÃncia eletroquÃmica). Os resultados indicaram que a energia de soldagem foi o fator que exerceu maior influÃncia sobre o teor mÃdio de ferrita na regiÃo do reforÃo das juntas. Na raiz, o formato de onda e o gÃs de proteÃÃo tambÃm influenciaram sobre esta caracterÃstica. Foi observado que o particionamento quÃmico entre as fases ferrita e austenita à maior na ZAC que na ZF, porÃm nÃo hà um comportamento claro da alteraÃÃo desta caracterÃstica em funÃÃo da energia de soldagem. A quantidade de austenita secundÃria (γ2) apresentou uma relaÃÃo nÃo linear com a energia de soldagem no reforÃo das juntas, sendo mais presente quando foi utilizado o nÃvel de energia de 1,0 kJ/mm, em mÃdia. Em relaÃÃo à resistÃncia à corrosÃo por pites, os ensaios de polarizaÃÃo potenciodinÃmica mostraram que a estabilidade dos pites depende da temperatura da soluÃÃo, e a nucleaÃÃo apresentou uma relaÃÃo com as regiÃes onde havia a precipitaÃÃo de nitretos. Somente nas regiÃes do reforÃo das juntas que apresentaram os maiores teores mÃdios de ferrita na ZF foi possÃvel observar a ocorrÃncia de pites estÃveis, em todos os outros casos estes ocorreram na ZAC. A espectroscopia de impedÃncia eletroquÃmica mostrou uma tendÃncia no aumento da resistÃncia à polarizaÃÃo nas juntas soldadas com o aumento do nÃvel de energia de soldagem. / Superduplex stainless steels are alloys that have good corrosion and mechanic resistance and, even more, are being used in substitution of austenitic stainless steels. However, welding thermal cycles may deteriorate these properties, affecting ferrite/austenite microstructural ratio and inducing intermetallic phases precipitation, thus requiring an adequate welding parameters selection. This problem might be critical in multipass welding due to repeated thermal cycles. Then, this work aims to study the effect of GMAW parameters on microstructural transformations and corrosion resistance of UNS S32750 superduplex stainless steel multipass welding. Thus, heat input (0,6 kJ/mm, 1,0 and 2,0 kJ/mm), shielding gas composition (98%Ar + 2%CO2 and 60%Ar + 38%He + 2%CO2), current wave shape (continuous and pulsed current) triangular weaving) were selected as the control factors and levels to be evaluated. Welds were performed on âhalf Vâ butt joints with 45 bevel angle and thickness of 22 mm. Mixed level fractional factorial technique was selected to the experimental design, resulting in eight butt joints welded. A microstructural characterization was performed on Weld Metal (WM) and Heat Affected Zone (HAZ) by Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). As response characteristics, one evaluated ferrite fraction and austenite mean spacing (both by image analysis), chemical composition of ferrite and austenite phases (Energy Dispersive X-ray Spectroscopy - EDS) and corrosion resistance (by electrochemical potentiodynamic polarization and electrochemical impedance spectroscopy). The results indicated that the heat input was the factor that exerted the greatest influence on the average content of ferrite at the cap of the joints. At root, the waveform and the shielding gas also influenced on this trait. It was observed that the elemental partitioning between ferrite and austenite phases is higher in the HAZ than in the WM, but there is not a tendency of this characteristic as a function of the heat input. The secondary austenite fraction presented a nonlinear relationship at the cap of the joints and the presence was greater when 1,0 kJ/mm heat input was used. Regarding to pitting corrosion resistance, polarization tests showed that the stability of the pits depends on the temperature of the solution, and the nucleation presents a relationship with the regions where there was precipitation of nitrides. Only at the region of the cap that had the highest average levels of ferrite in WM was possible to observe the occurrence of stable pits in this region, in all other cases they occurred in the HAZ. The electrochemical impedance spectroscopy showed a tendency to increase the polarization resistance of the welded joints with increasing the heat input level.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / O objetivo do presente trabalho à estudar o efeito da energia de soldagem sobre as transformaÃÃes microestruturais e a resistÃncia à corrosÃo na soldagem multipasse do aÃo inoxidÃvel superduplex UNS S32760 pelo processo MIG/MAG. A fim de atingir este objetivo, foram produzidas juntas soldadas variando-se a energia de soldagem nos seguintes nÃveis: 0,5 kJ/mm, 1,0 kJ/mm e 2,0 kJ/mm. Os valores de energia foram baseados em registros de qualificaÃÃo de procedimento de soldagem (RQPS) elaborados e aplicados nas unidades da PETROBRAS, exceto para a condiÃÃo de 2,0 kJ/mm, a qual foi extrapolada. As soldagens foram realizadas em juntas de tubos com 18 mm de espessura, com geometria em âJâ em uma bancada robotizada. Foi realizada uma caracterizaÃÃo microestrutural das regiÃes da Zona Fundida (ZF) e Zona Afetada pelo Calor (ZAC) pelas de Microscopia Ãtica (MO) e Microscopia EletrÃnica de Varredura (MEV). Como caracterÃsticas de resposta, avaliou-se o teor mÃdio de ferrita por anÃlise de imagens. A resistÃncia à corrosÃo foi avaliada pelas tÃcnicas eletroquÃmicas de polarizaÃÃo potenciodinÃmica com soluÃÃes de cloreto de sÃdio em diferentes concentraÃÃes (60g/L, 120g/L e 240g/L), polarizaÃÃo eletroquÃmica com reativaÃÃo potenciocinÃtica cÃclica (EPR-DL), teste eletroquÃmico de temperatura critica de pite seguindo a norma ASTM G150, ensaio de imersÃo em soluÃÃo de cloreto de ferro seguindo a norma ASTM G48 e ensaio de imersÃo em emulsÃes de petrÃleo preparadas com soluÃÃes de cloreto de sÃdio em diferentes concentraÃÃes (60g/L, 120g/L e 240g/L) e diferentes razÃes Ãgua/Ãleo (10%-90%, 30%-70% e 50%-50%). Os resultados indicaram que a energia de soldagem foi o fator que exerceu maior influÃncia sobre o teor mÃdio de ferrita na regiÃo da zona fundida da raiz das juntas. Houve precipitaÃÃes de nitretos de cromo em todas as energias e de fase sigma na energia de 1,0 kJ/mm e 2,0 kJ/mm. Os resultados do ensaio de EPR, assim como os ensaios de CPT mostraram que a zona fundida da energia de 1,0 kJ/mm se mostrou mais susceptÃvel a corrosÃo. Os ensaios de imersÃo seguindo a norma ASTM G48 mostraram que a temperatura onde ocorreu a formaÃÃo de pites com perda de massa considerÃvel quando as amostras entraram em contato com a soluÃÃo de cloreto de ferro foi em 50ÂC para todas as energias. E finalmente os ensaios de imersÃo em emulsÃes de petrÃleo, mostraram novamente que a energia de 1kJ/mm foi a que apresentou uma maior quantidades de pites. / The aim of this study was to evaluate the effect of heat imput in multipass welding on microstructural transformations and corrosion resistance of UNS S32760 superduplex stainless steel welded pipe joints by GMAW process. For this purpose, three levels of heat imput (0.5, 1.0 and 2.0 kJ/mm) were used. The heat imput values were based on records of welding procedure qualification (RWPQ) drawn up and applied in PETROBRAS units, except for the condition of 2.0 kJ/mm, which was an extrapolation. Weldings had been carried out for pipes with 18 mm thick, with joint geometry of J-groove. All welds were performed using a robotic workbench. The microstructural characterization of the weld regions like Fusion Zone (FZ) and Heat-Affected Zone (HAZ) were the performed by Ligth microscopy (LM) and scanning electron microscopy (SEM). The average ferrite content was determined by image analysis and was considerated as a characteristic response. The corrosion resistance was evaluated by electrochemical potentiodynamic polarization in sodium chloride solutions with different concentrations (60 g/L, 120 g/L and 240 g/L) aiming to simulate the concentration of chlorides in water production of oil reservoir of the pre-salt region. The to evaluate the electrochemical potentiokinetic reactivation cyclic of double loop (EPR-DL) corrosion was done to evaluate of susceptibility to corrosion. Electrochemical tests critical temperature for pitting according to ASTM G150, immersion tests in a solution of ferric chloride following the ASTM G48. Immersion tests in oil emulsions prepared with sodium chloride solutions at different concentrations (60 g/L 120 g/L and 240g/L), heated at 60ÂC and different ratio oil/water (10%-90%, 30%-70% and 50%-50%) were conduced. The results indicated that the welding heat imput was the factor that exerted the greatest influence on the average ferrite content in the fusion zone. There were precipitation of chromium nitrides at all heat imputs and sigma phase for the 1.0 kJ/mm and 2.0 kJ/mm. The EPR tests results as well as TCP tests showed that the fusion zone energy of 1.0 kJ/mm was more susceptible to corrosion. The immersion tests according to ASTM G48 showed that the temperature where the formation of pits occurred with considerable mass loss when the samples came in contact with the solution of ferric chloride was 50ÂC for all heat imputs. And finally, the immersion test in oil emulsions, showed again that the 1.0 kJ/mm test sample showed the greater amounts of pitting.

Abstract This thesis studies controlling factors that govern transverse hydrogen cracking in high-strength multipass weld metal (WM). The experiments were concerned with heavy-restraint Y- and U-Groove multipass cracking tests of shielded-metal arc (SMAW) and submerged-arc (SAW) weld metals. Results of tensile tests, hardness surveys, weld residual stress measurements and microstructural investigations are discussed. The analytical phase comprised numerical calculations for analysing the interactions between crack-controlling factors. The objectives were: (i) the assessment of WM hydrogen cracking risk by defining the Crack-No Crack boundary conditions in terms of 'safe line' description giving the desired lower-bound estimates, and (ii) to derive predictive equations capable of giving reliable estimates of the required preheat/interpass temperature T0/Ti for the avoidance of cracking. Hydrogen cracking occurred predominantly in high strength weld metals of Rp0.2 ≈ 580-900 MPa. At intermediate strengths of Rp0.2 ≈ 500-550 MPa, cracking took place in the cases where the holding time from welding to NDT inspection was prolonged to 7 days. Low strength WMs of Rp0.2 ≤ 480 MPa did not exhibit cracking under any conditions examined. Cracking occurrence was, above all, governed by WM tensile strength, weld diffusible hydrogen and weld residual stresses amounting to the yield strength. The appearance of cracking vanished when transferring from 40 to 6 mm thick welds. The implications of the holding time were more significant than anticipated previously. A period of 16 hrs in accordance with SFS-EN 1011 appeared much too short for thick multipass welds. Interpass time and heat input showed no measurable effect on cracking sensitivity, hence being of secondary importance. Equations were derived to assess the weld critical hydrogen content Hcr corresponding to the Crack-No Crack conditions as a function of either weld metal Pcm, yield strength Rp0.2 or weld metal maximum hardness HV5(max). For the calculation of safe T0/Ti estimates, a formula incorporating: (i) WM strength as a linear function of either weld carbon equivalent CET or weld HV5(max), (ii) weld build-up thickness aw in the form of tanh expression and (iii) weld diffusible hydrogen HD in terms of a combined [ln / power law] expression was found descriptive.

Neste trabalho, com objetivo de desenvolvermos dispositivos de limitação óptica, estudamos o processo de absorção de estado excitados em um grupo de tetrapiridil porfirinas com diferentes substituintes centrais (2H+, Zn2+, Ni2+, Cu2+). Para isso utilizamos a técnica de varredura – Z com pulsos de femto e picossegundos bem como com trem de pulsos. Desta forma, determinamos a dinâmica de absorção de estados excitados, para estas moléculas, obtendo parâmetros espectroscópicos tais como tempo de cruzamento intersistema, e as seções de choque de absorção dos primeiros estados excitados singleto e tripleto. Além disso, visando aproveitar os processos ópticos acumulativos de alguns materiais não lineares, em aplicação de limitação óptica, desenvolvemos uma nova geometria óptica denominada de limitador óptico de múltiplas passagens, a qual utiliza dois espelhos esféricos confocais e um espelho plano posicionado paralelamente a linha que une os espelhos esféricos. / In this work, aiming to develop optical limiting devices, we have studied excited state absorption process in a group of tetrapyridyl porphyrins with different central substitutes (2H+, Zn2+, Ni2+, Cu2+). We have employed Z-scan technique with femto and picosecond pulses as well as with pulse trains to determine the excited state absorption dynamics and obtain some spectroscopic parameters like intersystem crossing time and triplet and singlet excited state absorption cross-sections. Moreover, we have developed a new geometry for an optical limiter, named multipass optical limiter. It is formed by two confocal spherical mirrors together with a plane mirror placed in parallel with the line joining them.

Neste trabalho, com objetivo de desenvolvermos dispositivos de limitação óptica, estudamos o processo de absorção de estado excitados em um grupo de tetrapiridil porfirinas com diferentes substituintes centrais (2H+, Zn2+, Ni2+, Cu2+). Para isso utilizamos a técnica de varredura – Z com pulsos de femto e picossegundos bem como com trem de pulsos. Desta forma, determinamos a dinâmica de absorção de estados excitados, para estas moléculas, obtendo parâmetros espectroscópicos tais como tempo de cruzamento intersistema, e as seções de choque de absorção dos primeiros estados excitados singleto e tripleto. Além disso, visando aproveitar os processos ópticos acumulativos de alguns materiais não lineares, em aplicação de limitação óptica, desenvolvemos uma nova geometria óptica denominada de limitador óptico de múltiplas passagens, a qual utiliza dois espelhos esféricos confocais e um espelho plano posicionado paralelamente a linha que une os espelhos esféricos. / In this work, aiming to develop optical limiting devices, we have studied excited state absorption process in a group of tetrapyridyl porphyrins with different central substitutes (2H+, Zn2+, Ni2+, Cu2+). We have employed Z-scan technique with femto and picosecond pulses as well as with pulse trains to determine the excited state absorption dynamics and obtain some spectroscopic parameters like intersystem crossing time and triplet and singlet excited state absorption cross-sections. Moreover, we have developed a new geometry for an optical limiter, named multipass optical limiter. It is formed by two confocal spherical mirrors together with a plane mirror placed in parallel with the line joining them.

Parkinson's disease (PD) is a degenerative illness whose cardinal symptoms include rigidity, tremor, and slowness of movement. In addition to its widely recognized effects PD can have a profound effect on speech and voice.The speech symptoms most commonly demonstrated by patients with PD are reduced vocal loudness, monopitch, disruptions of voice quality, and abnormally fast rate of speech. This cluster of speech symptoms is often termed Hypokinetic Dysarthria.The disease can be difficult to diagnose accurately, especially in its early stages, due to this reason, automatic techniques based on Artificial Intelligence should increase the diagnosing accuracy and to help the doctors make better decisions. The aim of the thesis work is to predict the PD based on the audio files collected from various patients.Audio files are preprocessed in order to attain the features.The preprocessed data contains 23 attributes and 195 instances. On an average there are six voice recordings per person, By using data compression technique such as Discrete Cosine Transform (DCT) number of instances can be minimized, after data compression, attribute selection is done using several WEKA build in methods such as ChiSquared, GainRatio, Infogain after identifying the important attributes, we evaluate attributes one by one by using stepwise regression.Based on the selected attributes we process in WEKA by using cost sensitive classifier with various algorithms like MultiPass LVQ, Logistic Model Tree(LMT), K-Star.The classified results shows on an average 80%.By using this features 95% approximate classification of PD is acheived.This shows that using the audio dataset, PD could be predicted with a higher level of accuracy.

Les lasers femtoseconde à fibre dopée Yb sont aujourd'hui largement utilisés dans le domaine industriel parce que leur puissance moyenne est élevée. Cela permet d'accélérer les processus de fabrication. Cependant, les lasers à cristaux dopés Ti-Sa dominent dans les applications scientifiques parce que la durée d'impulsion est souvent le critère principal. Ces derniers produisent des impulsions d'une durée inférieure à 30 fs alors que les lasers à fibre dopée Yb, limités par la bande de gain du milieu amplificateur, ne génèrent que des durées de 300 fs.Cette thèse a permis de démontrer la génération, en sortie d'amplificateur à fibre dopée ytterbium, d'impulsion à haute énergie de quelques cycles optiques. Pour ce faire, la durée des impulsions est d'abord réduite en sortie d'amplificateur grâce à l'optimisation de l'architecture laser par façonnage spectral avant amplificateur de puissance afin de limiter l'impact du rétrécissement spectral par le gain. Cette technique permet de générer des impulsions de 130 fs.Afin d'obtenir des durées encore plus courte, une seconde technique de réduction de la durée des impulsions est utilisée après le laser utilisant l'auto-modulation de phase. Le milieu non-linéaire le plus courant utilisé pour des lasers de haute énergie est le capillaire rempli de gaz. L'utilisation de ce milieu nous permet de générer des durées d'impulsions de 15 fs mais est limité par son encombrement et sa transmission.Un deuxième schéma de compression non-linéaire est étudié afin de dépasser cette limitation : la Cellule Multi-Passage. L'utilisation de ce type d'architecture permet effectivement d'atteindre des transmission très élevées mais la contrainte sur le traitement des miroirs de la cellule limite le facteur de compression.Pour générer des durée d'impulsions de quelques cycles optiques, nous avons donc proposé de combiner les deux architectures étudiées en utilisant les avantages de chacune, permettant ainsi générer des impulsions de 2 cycles optiques (6.8 fs). Cette architecture globale permet la création de sources d'impulsions de haute énergie et de très courtes durées compactes et efficaces. / Femtosecond Yb–doped fiber lasers are commonly used in industry because of their high average power. This permits to increase the speed of fabrication processes. However, in scientific applications, the vast majority of high-intensity physics experiments are nowadays driven using Ti:Sapphire lasers. The key point in these applications is often the pulse duration and Ti:Sapphire lasers typically generate 30 fs pulses whereas Yb-doped fiber lasers generate only 300 fs pulses because of gain narrowing.In this thesis, we have sought to generate few-cycle pulses (< 10fs) from Yb-doped fiber lasers. First, we optimize the laser architecture by using spectral amplitude shaping in order to counterbalance gain narrowing. This allows to generate 130 fs pulse duration.To obtain even shorter pulses we added a nonlinear compression set-up after the laser, based on self-phase modulation. For high energy, the most commonly used nonlinear medium is gas-filled capillaries. This set-up allows us to generate 15 fs pulse duration. Nevertheless the transmission of the set-up is limited to 50 %.A second scheme is studied which overcomes this limitation: the gas-filled Multi-Pass Cell. We experimentally demonstrate for the first time nonlinear compression of a high-energy Yb-doped fiber source in this novel implementation. The use of this architecture permits to reach high transmission but the compression factor at the output of the set-up is limited by the mirror coatings.To produce few-cycles pulse duration, we combine the two aforementionned schemes, allowing the generation of two-cycle (6.8 fs) pulse duration with a high overall transmission. This global architecture will enable a new generation of high-energy compact few-cycle laser sources.

<p dir="ltr"> Nowadays, inkjet printers are widely used all around the world. But how do they transfer the digital image to a map that can control nozzle firing? In this preliminary report, we briefly illustrate that part of the printing pipeline that starts from a halftone image and ends with Hardware Ready Bits (HRBs). We also describe the implementation of the multi-pass printing method with a designed print mask. HRBs are used to read an input halftone CMY image and output a binary map of each color to decide whether or not to eject the corresponding coloranr drop at each pixel position. In general, for an inkjet printer, each row of the image corresponds to one specific nozzle in each swath so that each swath will be the height of the printhead \cite{torpey1997multipass}. To avoid visible white streaks due to clogged or burned out color nozzles, the method called multi-pass printing is implemented. Subsequently, the print mask is introduced so that we can decide during which pass each pixel should be printed. Once we figure out how to transfer the digital image to our printing signals. We start to think about improving the color performance for the inkjet printer. In one of our previous papers \cite{wang2020developing}, we described the color management pipeline that was applied to our nail inkjet printer, which is used to map the source gamut to the destination printer gamut. However, the resulting prints are not as vivid as we would like to have, since those prints are not well saturated. To obtain more saturated prints, we propose a saturation enhancement method based on image segmentation and hue angle. This method will not necessarily give us the closest representation of the colors within the input image but could give us more saturated prints. The main idea of our saturation enhancement method is to keep the lightness and hue constant, while stretching the chroma component.</p><p><br></p><p dir="ltr"> In one of our previous papers \cite{hu2021improving}, we mostly focused on the color saturation problem in our inkjet printer. However, our partner reported that there are some boundary noise pixels on the background, which are quite visible when the background is white. By checking the pipeline of our printing procedure, we realized that the noise stray dots are generated during the halftoning procedure. This part of the dissertation is dedicated to separating the white background from the foreground, which enables us to constrain the error diffusion process inside the white background. The main idea is to apply image segmentation, which could help us to precisely extract the background.</p><p><br></p><p dir="ltr"> Lastly, inspired by the paper \cite{smith2023chiral}, we decided to design an aperiodic clustered-dot screen, which may have better performance compared to the current DBS screen. This screen generation method is offline, so the time cost is not our main consideration. The output halftone result is what we concentrate on. This screen is generated based on a polygon shape, which is called tile(1,1) defined by the paper \cite{smith2023chiral}. We keep extending this single polygon shape to obtain the combination aperiodic shape that is called a supertile. After obtaining the final supertile, we assigned each tile(1,1) shape to either a dot or a hole based on the complementary symmetry property. Finally, based on some interpolation methods, we generate the threshold matrix. </p>

The goal of this thesis was to create graphical demo in OpenGL, which would appropriately react on music, which is inseparable part of graphical demos. Work consists of two main parts, first is programming of real-time graphical engine, second is creating graphical demo which would run on graphical engine created in first part. First part focues on programming of OpenGL based application, which would render scene in real-time using techniques from computer graphics. Second part focuses mainly on graphical activity, which includes 3D modelling, texturing, creating animation and connection to music (reaction of environment and animations to changes in music)