Receiver design for nonlinearly distorted OFDM : signals applications in radio-over-fiber systems

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Universidade do Porto. Faculdade de Engenharia. 201

Algoritmos de valores e vectores próprios no âmbito da análise de estruturas

Tese de mestrado integrado. Engenharia Civil (especialização em Estruturas). Faculdade de Engenharia. Universidade do Porto. 200

Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference

The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS) of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics) and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs) of the metals and ceramics. Verabond (VB) Ni-Cr-Be alloy, Verabond II (VB2), Ni-Cr alloy, Pors-on 4 (P), Pd-Ag alloy, and IPS (I) and Duceram (D) ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length) made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length) of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01) for the MCBS test results (MPa), with PI showing higher MCBS (67.72) than the other pairs, which did not present any significant differences. The CTE (10-6 oC-1) differences were: VBI (0.54), VBD (1.33), VB2I (-0.14), VB2D (0.63), PI (1.84) and PD (2.62). Pearson's correlation test (r=0.17) was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.FAPES

SINDROME DE FOURNIER RECIDIVADA

The Fournier’s Syndrome is characterized by a necrotizing infection that can affect regions such as perineum, thighs, scrotum, thigh roots and lower abdomen. It begins insidiously, but progresses with great tissue loss and is of difficult handling. It is an uncommon morbidity of the population at large. Recurrence is poorly documented, which makes its occurrence atypical in medical practice. The mortality rate varies from 10% to 30.8% in Brazil without changes over time despite advances in technology and in surgical techniques. The objective of this study is to demonstrate a recurrence of the syndrome in a male, 46-year-old patient, with diabetes, hypertension and grade III obesity. The patient was treated in a timely manner with satisfactory clinical and aesthetic outcomes.RESUMO A síndrome de fournier caracteriza-se por uma infecção necrozante que pode acometer região perineal, coxa, escroto, raízes de coxa e abdome inferior. Tem seu início insidioso, porém com progressão com grande perda de tecidos e difícil manejo. É uma morbidade incomum da população em geral. A recidiva é pouco documentada tornando-se atípico na prática médica.  A taxa de mortalidade varia de 10% a 30.8% no Brasil sem mudança no decorrer do tempo apesar dos avanços tecnológicos e de técnicas cirúrgicas. O objetivo deste estudo é demonstrar uma recidiva da Síndrome em um paciente masculino, 46 anos com diabetes, hipertensão e obesidade grau III. Foi tratada em tempo hábil com bom desfecho clínico e estético

Caracterização de lesões de pele em imagens digitais a partir da máquina de vetor de suporte

Este trabalho apresenta um método para a caracterização das lesões de pele, a partir das características da regra ABCD (assimetria, borda, cor e diâmetro) e análise de textura. As características ABCD são obtidas de acordo com o dermatologista e a textura das imagens é definida pela sua dimensão fractal, por meio do método box-counting. As características de assimetria e textura extraídas das imagens são utilizadas como entradas para o classificador SVM (Máquina de Vetor de Suporte), que é uma técnica baseada em aprendizado estatístico, utilizada para o reconhecimento de padrões em imagens. O SVM classifica a assimetria das lesões em simétrica ou assimétrica e a textura das lesões em lisa ou rugosa. Todas as informações referentes as características extraídas da lesão são passadas ao dermatologista com o intuito de auxiliá-lo no diagnóstico

Análise e caracterização de lesões de pele para auxílio ao diagnóstico médico

Neste capítulo, propõe-se uma metodologia híbrida para detectar e extrair os contornos de lesões de pele a partir de imagens, bem como a definição de características usualmente utilizadas no diagnóstico de lesões. O método de segmentação por divisão e união (Split and Merge) foi adotado para detectar a lesão e obter o seu contorno inicial. Em seguida, este contorno é refinado pelo modelo de contorno ativo tradicional. Características da lesão usadas na regra ABCD, são definidas a partir do contorno refinado. Os resultados experimentais indicam que o método proposto é promissor para detectar as áreas com lesão e extrair seus contornos a partir de imagens, mantendo suas características

Uma metodologia híbrida para segmentação de lesões de pele

Computer aided methods are widespread demanded in medical applications. As such, methodologies to automatic extract contours are desired to aid the automatic diagnosis of skin lesions. In this work, we propose a hybrid method to detect and extract skin lesion contours from dermatoscopic images. In the proposed method, to obtain the contour that includes all lesion regions, the region growing technique, based on a Quadtree implementation, is used to extract an initial contour. Afterwards, this contour is refined by using a traditional active contour model. Experimental results indicate that the proposed method is promising to detect skin lesion areas and to extract their contours from dermatoscopic images. Actually, the extracted contours maintain the original lesion features that are usually used in their diagnosis. Additionally, the results allow concluding that the method is able to detect lesion regions even in images with strong noise, like in images of the scalp

Uma metodologia híbrida para segmentação de lesões de pele

Computer aided methods are widespread demanded in medical applications. As such, methodologies to automatic extract contours are desired to aid the automatic diagnosis of skin lesions. In this work, we propose a hybrid method to detect and extract skin lesion contours from dermatoscopic images. In the proposed method, to obtain the contour that includes all lesion regions, the region growing technique, based on a Quadtree implementation, is used to extract an initial contour. Afterwards, this contour is refined by using a traditional active contour model. Experimental results indicate that the proposed method is promising to detect skin lesion areas and to extract their contours from dermatoscopic images. Actually, the extracted contours maintain the original lesion features that are usually used in their diagnosis. Additionally, the results allow concluding that the method is able to detect lesion regions even in images with strong noise, like in images of the scalp

Vortex-induced vibrations of a freely vibrating cylinder near a plane boundary: experimental investigation and theoretical modelling

This work reports on experiments that were performed with a freely vibrating cylinder exposed to currents and placed near a plane boundary parallel to the cylinder axis. It is observed that the proximity of the boundary affects the vertical response of the cylinder in two ways: (i) for gaps between 0.75 and 2 diameters (D), the amplitude of oscillation is reduced; (ii) for gaps smaller than 0.75D, the cylinder impacts the boundary, resulting in an increase of amplitudes and frequencies of oscillations as the flow is accelerated. The in-line force acting on the cylinder is also examined, and the dependency of its harmonic components on the flow velocity and distance to the boundary is evaluated. Besides the typical amplification of the mean component inside the lock-in region, it is also observed that as the cylinder is placed closer to the boundary, the harmonic component with the frequency of the vertical oscillations increases, while the component with twice that frequency decreases in similar amount. Based on the experimental observations, an existing wake-oscillator model for vortex-induced vibrations is enhanced in order to account for the effect of the boundary. The proposed model introduces an effective damper that is activated when the cylinder reaches a certain distance from the boundary, and a damper/spring set representing the rigidity of the boundary and the dissipation of energy due to impact