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Restauração de imagens em vibro-acustografia
(Universidade Federal de São Carlos, 2008-03-10) Leite, Talita Perciano Costa; Mascarenhas, Nelson Delfino d'Ávila; https://lattes.cnpq.br/0557976975338451; https://lattes.cnpq.br/6877649058117092
Vibro-acoustography is an imaging modality that produces a map of the mechanical response of an object to a localized dynamic radiation force produced by an ultrasound field. This technique has been studied and used in clinical applications as to image calcification in breast tissue and arteries. This work aims to apply restoration algorithms to vibro-acoustography images. The point spread function (PSF) of the system is defined in terms of the acoustic emission of a point-target in response to a dynamic radiation stress of ultrasound. This PSF is used to form the image taking into account depth-of-field effects. The main problem found in the vibro-acoustography image formation is the high blur that this PSF causes to the acquired images, mainly in the depth direction (axial axis). To form the degraded image, digital phantoms were used, of breast for instance, simulating tissues with lesion-like inclusions. Moreover, Gaussian noise is added to the blurring model because of the characteristics of the images acquisition by the real vibro-acoustography system. Restoration filters are studied and applied to the images, and their results are compared visually and quantitatively; acceptable results are obtained. Problems found in the implementation of the restoration algorithms for this system are studied and possible solutions are discussed and applied to the final implementations. With the use of the algorithms high quality images were obtained if compared with the degraded versions, fact that justify the use of these methods in this kind of image. Moreover, the algorithms implemented in this work can be applied to imaging problems with similar characteristics.
O problema da verdade na filosofia de L. Wittgenstein: percurso da semântica à pragmática
(Universidade Federal de São Carlos, 2008-03-10) Silva, Eduardo Simões; Cass, Mark Julian Richter; https://lattes.cnpq.br/6549114665097353; https://lattes.cnpq.br/4739161935290553
This study aims to examine the problem of truth as it presents itself in L. Wittgenstein's philosophy. Problem this, which will be presented not isolated from discussions on the truth raised in the history of philosophy, but within a broader context of the theories of truth in their projects. Thus, the work will develop in the following way: in the first chapter will be addressed various theories of truth, without any judgment of value to be raised as their projects (it is a chapter whose function is strictly descriptive). In the second chapter, will be presented the philosophy of the Tractatus Logico-Philosophicus (1922) of Wittgenstein, specifically, with regard to the interest of this study, namely, the conception of truth as correspondence (Truth and Figuration) - with this chapter, claims to identify the discussion on the truth in Wittgenstein with a broader project of truth. In the third chapter, will be addressed to the philosophy of Philosophical Investigations (1945) as a radical contrast to the tractatian vision of the problem of truth, where the author explains his criticism of traditional concepts of the meaning in favor of a pragmatic use of the language. It is expected with this chapter to establish a link between the Tractatus and Philosophical Investigations, or rather indicates possible errors which Wittgenstein himself would have found in Tractatus, mistakes that would justify the changes of direction of the first to the second work. What Wittgenstein proposed from Philosophical Investigations is a new method to avoid conceptual confusions, and the emphasis will no longer be in the search for the essence of language or the logical way of proposition, but in the use we make of language in our daily practices
Desenvolvimento e caracterização de filmes tubulares de nanocompósitos de PEAD/EVA/argila organofílica
(Universidade Federal de São Carlos, 2008-03-10) Marini, Juliano; Bretas, Rosario Elida Suman; https://lattes.cnpq.br/2805349172281345; https://lattes.cnpq.br/4533610255047654
In this work, the use of ethylene-vinyl acetate copolymer (EVA) in substitution to compatibility agents normally employed in the production of high density polyethylene (HDPE) nanocomposites (such as polyethylene grafted with maleic anhydride - PEMA) was evaluated due to its intrinsic polarity and relative low cost. Two EVAs with different melt flow indexes and vinyl acetate contents and two organophilic clays treated with different organic surfactants were used. It was verified that EVA with lower viscosity and higher polarity showed better interactions with the clay treated organically with polar surfactant. However, these characteristics reduced the HDPE/EVA compatibility. HDPE/EVA/MMT nanocomposites were obtained through melt mixing and subsequently blown as films. An Intercalated nanocomposite (HDPE/EVA 8/C15A) and a nanocomposite characterized by the presence of tactoids of the organoclay (HDPE/EVA 25/C30B) were produced. From rheological, morphological and permeation analysis it was found that the addition of clay modified the interfacial interactions between HDPE and EVA, increasing the system compatibility when compared to the HDPE/EVA blends behavior. Comparing with the HDPE/EVA blends, the better compatibility in nanocomposites were followed by an increase in elastic modulus, yielding and rupture behaviors and permeability properties. But these properties did not increase when compared with the pure HDPE film. The best results were obtained with the HDPE/EVA 8/C15A nanocomposite.