Papers by Keyword: Tomography

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Authors: Eleni Mangiorou
Abstract: Τhe incidence of and mortality from cancer have been increasing steadily for the past 50 years. Most cancers are not localized when first detected, but early detection is mandatory to improve prognosis. In this article, we performed a comparison of four basic methods of tomographic imaging, Positron emission tomography (PET), the computerized tomography (CT), Magnetic Resonance Imaging (MRI) scanner and the ultrasound scanner (US), in respect to their advantages and disadvantages.
Authors: Sam Yang, Scott Furman, Andrew Tulloh
Abstract: A mathematical model has been developed for predicting material compositional microstructures using measured data as constraints. Examples of measured data include 3-D sets of tomography data, 2-D sets of compositional data on surfaces and sections, and material absorption and interaction properties. The model has been partially implemented as a MS-Windows application. Reasonable agreement has been obtained between the numerical predictions from the software and the simulated data. The predicted microstructures could be used to study various material properties such as porosity distribution, diffusion and corrosion.
Authors: J. Kedit
Abstract: This paper is a study of cross-sectional imaging of a specimen with gamma transmission tomography system. The aim of this paper is to create the cross-section image of a warhead specimen with the gamma transmission tomography system for inspection the air gaps, cracks find them from the specimen. The compositions of specimen are including cylindrical steel , steel balls ,rubber and plaster. The steel balls are formed in the cylindrical steel and explosive is replaced by plaster. Two holes and a rectangle shape are formed in the plaster. The results from cross-section image from the reconstruction shows holes but the thin rectangle shape is invisible.
Authors: Salehuddin Ibrahim, Nurfaizah Md Ruhi, Mohd Amri Md Yunus, Belal Ghanem, Mahdi Faramarzi
Abstract: This paper presents an investigation on the use of tomography system using using optical and electrodynamic sensors. The system obtains data from both sensors which detect the flow in a process pipe. Information on the flow is processed in order to display the image reconstruction of a solid flow.
Authors: Fabrizio Fiori, Emmanuelle Girardin, Alessandra Giuliani, Adrian Manescu, Serena Mazzoni, Franco Rustichelli, Evzen Amler
Abstract: The rapid development of new materials and their application in an extremely wide variety of research and technological fields has lead to the request of increasingly sophisticated characterization methods. In particular residual stress measurements by neutron diffraction, small angle scattering of X-rays and neutrons, as well as 3D imaging techniques with spatial resolution at the micron or even sub-micron scale, like micro-and nano-computerized tomography, have gained a great relevance in recent years.Residual stresses are autobalancing stresses existing in a free body not submitted to any external surface force. Several manufacturing processes, as well as thermal and mechanical treatments, leave residual stresses within the components. Bragg diffraction of X-rays and neutrons can be used to determine residual elastic strains (and then residual stresses by knowing the material elastic constants) in a non-destructive way. Small Angle Scattering of neutrons or X-rays, complementary to Transmission Electron Microscopy, allows the determination of structural features such as volume fraction, specific surface and size distribution of inhomogeneities embedded in a matrix, in a huge variety of materials of industrial interest. X-ray microtomography is similar to conventional Computed Tomography employed in Medicine, allowing 3D imaging of the investigated samples, but with a much higher spatial resolution, down to the sub-micron scale. Some examples of applications of the experimental techniques mentioned above are described and discussed.
Authors: Michael Nöthe, Matthias Schulze, Rainer Grupp, Bernd Kieback, A. Haibel, John Banhart
Abstract: The decrease of the distance between particle centers due to the growth of the sinter necks can be explained by the well known two-particle model. Unfortunately this model fails to provide a comprehensive description of the processes for 3D specimens. Furthermore, there is a significant discrepancy between the calculated and the measured shrinkage because particle rearrangements are not considered. Only the recently developed analysis of the particle movements inside of 3D specimens using micro focus computed tomography (μCT), combined with photogrammetric image analysis, can deliver the necessary experimental data to improve existing sintering theories. In this work, μCT analysis was applied to spherical copper powders. Based on photogrammetric image analysis, it is possible to determine the positions of all particle centers for tracking the particles over the entire sintering process and to follow the formation and breaking of the particle bonds. In this paper, we present an in-depth analysis of the obtained data. In the future, high resolution synchrotron radiation tomography will be utilized to obtain in-situ data and images of higher resolution.
Authors: Han Seo Ko, Yong Jae Kim, Oh Chae Kwon, Koji Okamoto
Abstract: Velocity and density distributions of a high-speed and initial CO2 jet flow have been analyzed simultaneously by a developed three-dimensional digital speckle tomography and a particle image velocimetry (PIV). Three high-speed cameras have been used for the tomography and the PIV since a shape of a nozzle for the jet flow is asymmetric and the initial flow is fast and unsteady. The speckle movements between no flow and CO2 jet flow have been obtained by a cross-correlation tracking method so that those distances can be transferred to deflection angles of laser rays for density gradients. The three-dimensional density fields for the high-speed CO2 jet flow have been reconstructed from the deflection angles by the real-time tomography method, and the two-dimensional velocity fields have been calculated by the PIV method simultaneously.
Authors: Yan Cheng, Paul Hagan, Rudrajit Mitra
Abstract: This paper discusses the development of acoustic emission tomography to identify structural discontinuities in concrete. An algorithm was developed to reconstruct velocity tomographs of the interior of the material. Both theoretical analysis and experimental data were used to determine best sensor array geometry. Experiments on a concrete block with artificial fracture indicate that the technique can be used to identify structural discontinuities.
Authors: Jakub Jaroszewicz, Hubert Matysiak, Jakub Michalski, Kamil Matuszewski, Krzysztof Kubiak, Krzysztof Jan Kurzydlowski
Abstract: X-ray micro-computed tomography system has been used for visualization in two- (2-D) and three dimensions (3-D) of the dendrite structure and pores in single-crystals fabricated by Bridgman investment casting technique. The system described in the paper reconstructs 3-D geometry from a set of 2-D images obtained by multiple slicing of an X-ray radiography image. The results obtained in this study demonstrate the effect of withdrawal rate on the primary dendrite arm spacing and porosity in single-crystal made of CMSX-4 alloy.
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