Fractal analysis of weld defect patterns obtained by radiographic tests

This paper presents a fractal analysis of radiographic patterns obtained from specimens with three types of inserted welding defects: lack of fusion, lack of penetration, and porosity. The study focused on patterns of carbon steel beads from radiographs of the International Institute of Welding (IIW). The radiographs were scanned using a greyscale with 256 levels, and the fractal features of the surfaces constructed from the radiographic images were characterized by means of Hurst, detrended-fluctuation, and minimal-cover analyses. A Karhunen-Loeve transformation was then used to classify the curves obtained from the fractal analyses of the various images, and a study of the classification errors was performed. The obtained results indicate that fractal analyses can be an effective additional tool for pattern recognition of weld defects in radiographic tests.Comment: 7 pages, 2 figures. To appear AIP Conference Proceedings - QNDE 200

Modelling radiation emission in the transition from the classical to the quantum regime

An emissivity formula is derived using the generalised Fermi-Weizacker-Williams method of virtual photons which accounts for the recoil the charged particle experiences as it emits radiation. It is found that through this derivation the formula obtained by Sokolov et al using QED perturbation theory is recovered. The corrected emissivity formula is applied to nonlinear Thomson scattering scenarios in the transition from the classical to the quantum regime, for small values of the nonlinear quantum parameter \chi. Good agreement is found between this method and a QED probabilistic approach for scenarios where both are valid. In addition, signatures of the quantum corrections are identified and explored.Comment: 11 pages, 4 figures, submitted for publicatio

Optimization conditions of UV-C radiation combined with ultrasound-assisted extraction of cherry tomato (Lycopersicon esculentum) lycopene extract

The aim of this work was to study the effect of UV-C radiation on ultrasound assisted extraction (UAE) of cherry tomato bioactive compounds. Cherry tomatoes were exposed to two UV-C radiation doses (0.5 and 1.0 J cm−2 ) and stored at 20 ± 0.5 oC for 7 days. Next, they were lyophilized, and the bioactive compounds were extracted by UAE at 20 KHz. To evaluate the effectiveness of the extraction process of the bioactive compounds, a CCRD (central composite rotational design) was used together with RSM (response surface methodology), for extraction times from 4 to 12 minutes and concentrations (g of lyophilized product / L of ethanol) of 1:10, 1:20 and 1:30. The extracts obtained from the irradiated tomatoes presented 5.8 times more lycopene content than the controls and higher antioxidant activity was obtained for 4 and 8 min, in the concentrations 1:10 and 1:20 (m v−1). Through numerical model optimization, optimal extraction conditions were obtained. The results demonstrated that by previously irradiating tomatoes with UV-C light, the UAE yielded considerably higher amounts of lycopene and other bioactives.CNPq (National Council of Technological and Scientific Development, Brazil), Erasmus Mundus action 2; Fellow Mundus Project; Department of Chemical Engineering and Food Engineering (UFSC - Brazil) and the Department of Food Engineering (UAlg - Portugal) .info:eu-repo/semantics/publishedVersio

Comparison of the Spherical Averaged Pseudopotential Model with the Stabilized Jellium Model

We compare Kohn-Sham results (density, cohesive energy, size and effect of charging) of the Spherical Averaged Pseudopotential Model with the Stabilized Jellium Model for clusters of sodium and aluminum with less than 20 atoms. We find that the Stabilized Jellium Model, although conceptually and practically more simple, gives better results for the cohesive energy and the elastic stiffness. We use the Local Density Approximation as well as the Generalized Gradient Approximation to the exchange and correlation energies.Comment: 13 pages, latex, 8 figures, compressed postscript version available at http://www.fis.uc.pt/~vieir

Avaliação econômica de um sistema agroflorestal para conexão de fragmentos da mata atlântica .

Este trabalho teve por objetivo realizar uma avaliação econômica de um corredor agroflorestal implantado em fevereiro de 2005 na Fazendinha Agroecológica do km 47, Seropédica – RJ. Foram plantadas espécies de ciclo curto, como o aipim, banana, cana e abacaxi e 25 espécies florestais. As culturas agrícolas anuais foram avaliadas utilizando-se os critérios financeiros de avaliação de projetos: Valor Presente Líquido (VPL) e Razão Benefício/Custo (RB/C). O custo total acumulado após três anos de implantação chegou a R$16.000,00/ha. A receita gerada, de R$ 6.000,00/ha, foi suficiente para pagar cerca de 38% desses custos. O cultivo da mandioca foi o mais rentável, sendo responsável por 65% da receita gerada. As culturas de aipim e cana apresentaram VPL positivo de R$1.218,34 e R$ 144,33, respectivamente, indicando que a produção foi suficiente para pagar os custos de implantação e gerar excedentes. O abacaxi apresentou VPL negativo de R$2.224,54. Considerando-se a relação benefício/custo (B/C), o aipim apresentou um valor de 6,80, indicando que para cada real gasto com a implantação desta cultura obteve-se R$ 6,80 de retorno. Para a cultura da cana, chegou-se a relação B/C de 1,27. Para o abacaxi a relação foi de 0,22. A relação benefício/custo total do sistema foi de 0,35. Embora o rendimento gerado durante os dois primeiros anos tenha sido significativo, este ainda não foi suficiente para pagar todos os custos de implantação, sendo recomendada a introdução de novas culturas de ciclo curto ou frutíferas para incrementar a geração de renda ano a ano.bitstream/item/42957/1/BOP-60.pd