This thesis deals with processing of data obtained by DCE-MRI, which uses magnetic resonance to track the propagation of contrast agents in the blo- odstream. Patient is given a contrast agent and then a series of images of the target area is taken. The output is a set of image data and perfusion maps. Work employs segmentation method which uses graph cuts to interactively look for the tumor, and evaluates it according to its shape properties. Study of whole data sets is simplified by image fusion methods.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / à de conhecimento geral que o desempenho de misturas asfÃlticas com relaÃÃo aos principais defeitos do pavimento (deformaÃÃo permanente, trincamento por fadiga e trincamento tÃrmico) està diretamente ligado Ãs propriedades dos agregados que as constituem. A metodologia tradicional de caracterizaÃÃo de agregados, principalmente em relaÃÃo à forma, à angularidade e à textura, pode se tornar dispendiosa e nÃo fornecer resultados precisos, pois, alÃm de muitas vezes combinar mais de uma propriedade em apenas um ensaio, estes parÃmetros sÃo avaliados a partir de uma mÃdia de valores que pode nÃo representar bem os materiais estudados. Sendo assim, jà existem, na literatura, diversas tÃcnicas de Processamento Digital de Imagens (PDI) que podem ser utilizadas com o intuito de caracterizar agregados de forma mais completa e realista. Uma destas tÃcnicas à por meio do uso do equipamento Aggregate Image Measurement System (AIMS), desenvolvido para analisar forma, angularidade e textura superficial de agregados graÃdos e miÃdos, atravÃs de diferentes mÃtodos. Acredita-se que, diferentes pedreiras podem produzir agregados com propriedades distintas entre si devido aos diversos processos de desmonte, de britagem, de controle de qualidade e de armazenamento dos materiais. O objetivo geral do presente trabalho à avaliar o potencial do uso do PDI na anÃlise das propriedades de forma, de angularidade e de textura de agregados provenientes de fontes distintas e na anÃlise da estrutura interna de misturas asfÃlticas compostas por esses agregados. Foram obtidos e caracterizados agregados provenientes de trÃs pedreiras distintas, todas localizadas no estado do CearÃ. Os agregados foram analisados no AIMS separando-se os diversos tamanhos de suas partÃculas, e os resultados obtidos para o material proveniente de cada pedreira foram comparados entre si. AlÃm disso, misturas asfÃlticas compostas por esses agregados foram analisadas em relaÃÃo a sua estrutura interna e em relaÃÃo a suas propriedades mecÃnicas. Os principais resultados obtidos levaram à conclusÃo de que os agregados estudados sÃo semelhantes no que diz respeito a suas propriedades de forma, de angularidade e de textura. Em relaÃÃo Ãs propriedades mecÃnicas das misturas compostas por esses agregados, os resultados mostram que estas se comportaram de maneira similar, o que provavelmente se deve Ãs caracterÃsticas tambÃm similares de seus agregados. / It is a general consensus that the mechanical performance of asphalt mixtures with respect to the pavementsâ main distresses (permanent deformation, fatigue cracking and thermal cracking) is directly related to the aggregatesâ properties used in those mixtures. The traditional methodology of characterizing aggregates, mainly in relation to shape properties, such as form, angularity and texture, can be very time-consuming. It also does not provide precise results, because it combines more than one property in a single test result. Another disadvantage is the fact that these methodologies also provide average values that may not represent well the evaluated materials. There are already in the literature several Digital Image Processing (DIP) techniques that can be used with the purpose of characterizing aggregates in a more complete and realistic way. One of them is the Aggregate Image Measurement System (AIMS), equipment developed to analyze properties, such as: shape, angularity, and superficial texture of coarse and fine aggregates, through different methods. It is believed that different quarries can produce aggregates with very distinct properties, due to the several used rock blasting and crushing processes, quality control activities and material storage methodology. The main objective of this research is to evaluate the potential use of DIP to analyze shape, angularity and texture of aggregates from different sources and to analyze asphalt mixtures internal structure constituted by those aggregates. Aggregates from three different quarries, all located in the State of CearÃ, were obtained and characterized. The aggregates were analyzed using AIMS, for different sizes, and the results were compared. Besides that, the asphalt mixtures constituted with these aggregates were analyzed regarding their internal structure and their mechanical characteristics. The main results obtained in this study led to conclude that the aggregates used in this research are very similar in respect to their form, angularity and texture properties. With respect to the mechanical properties of the mixtures constituted by these aggregates, the results show that their behavior is also very similar, which is probably due to the similar characteristics of their aggregates.

Pavement layers are constructed using a combination of materials, of which rock aggregates constitute a larger proportion. Current understanding is that the performance of pavements is dependent on the aggregate shape properties which include form, angularity and surface texture. However, direct and accurate measurements of aggregate shape properties remain a challenge. The current standard test methods used to evaluate aggregate shape properties cannot measure these properties accurately. Among the reasons contributing to the difficulties in the determination of aggregate shape properties is irregular shapes of aggregate particles. Therefore, current research efforts focus on developing accurate, reliable and innovative techniques for evaluation of aggregate shape properties. The work presented in this dissertation contributes to the current innovative research at the Council for Scientific and Industrial Research (CSIR) in South Africa, to automate the measurement of aggregate shape properties. The CSIR’s present research is aimed at improving pavement performance through better materials characterisation, using laser scanning and advanced modelling techniques. The objective of this study was to investigate improved techniques for the determination of aggregate shape properties using analytical and laser scanning techniques. A three-dimensional (3-D) laser scanning device was used for scanning six types of aggregate samples commonly used for construction of pavements in South Africa. The laser scan data were processed to reconstruct 3-D models of the aggregate particles. The models were further analysed to determine the shape properties of the aggregates. Two analysis approaches were used in this study. The first approach used the aggregate’s physical properties (surface area, volume and orthogonal dimensions) measured by using laser scanning technique to compute three different indices to describe the form of aggregates. The computed indices were the sphericity computed by using surface area and volume of an aggregate particle, the sphericity computed by using orthogonal dimensions of an aggregate particle, and the flat and elongated ratio computed by using longest and smallest dimensions of an aggregate particle. The second approach employed a spherical harmonic analysis technique to analyse the aggregate laser scan data to determine aggregate form, angularity and surface texture indices. A MATLABTM code was developed for analysis of laser scan data, using the spherical harmonic analysis technique. The analyses contained in this dissertation indicate that the laser-based aggregate shape indices were able to describe the shape properties of the aggregates studied. Furthermore, good correlations were observed between the spherical harmonic form indices and the form indices determined by using the aggregate’s physical properties. This shows that aggregate laser scanning is a versatile technique for the determination of various indices to describe aggregate shape properties. Further validation of the laser-based technique was achieved by correlating the laser-based aggregate form indices with the results from two current standard tests; the flakiness index and the flat and elongated particles ratio tests. The laser-based form indices correlated linearly with both, the flakiness index and the flat and elongated particles ratio test results. The observed correlations provide an indication of the validity of laser-based aggregate shape indices. It is concluded that the laser based scanning technique could be employed for direct and accurate determination of aggregate shape properties. / Dissertation (MEng)--University of Pretoria, 2013. / gm2013 / Civil Engineering / Unrestricted