Searched for: contributor:"Gisolf, A. (promotor)"
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document
Ozmen, N. (author)
The main focus of this thesis is on modeling acoustic wavefield propagation and implementing imaging algorithms for breast cancer detection using ultrasound. As a starting point, we use an integral equation formulation, which can be used to solve both the forward and inverse problems. This thesis contains three main topics: forward modeling,...
doctoral thesis 2014
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Chougrani, K. (author)
Detection and sizing of closed cracks is challenging as these cracks exhibt a transparent behavior when interacting with ultrasonic waves. To face this challenge, high amplitude ultrasonic waves are used by which harmonics are generated at the crack interface. Exploting this non-linear response, the probability of detection and sizing of such...
doctoral thesis 2014
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Kutscha, H. (author)
Many seismic data processing and imaging processes require densely and regularly sampled data, whereas the actual measurements are mostly irregularly and sparsely sampled. Therefore, seismic data reconstruction methods are utilised as a pre-processing step. Within the class of transformation-based reconstruction techniques, observed seismic data...
doctoral thesis 2014
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Demi, L. (author)
The design and optimization of medical ultrasound modalities require a method for modeling the propagation of pressure wave fields through biomedical tissue. This method needs to be capable of modeling various phenomena, e.g. nonlinear propagation, attenuation, and scattering caused by arbitrary inhomogeneities in the acoustic properties of the...
doctoral thesis 2013
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Haffinger, P.R. (author)
Full waveform inversion is a tool to obtain high-resolution property models of the subsurface from seismic data. However, the technique is computationally expens- ive and so far no multi-dimensional implementation exists to achieve a resolution that can directly be used for seismic interpretation and characterisation. In this thesis we discuss a...
doctoral thesis 2013
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Alles, E.J. (author)
Intravascular ultrasound (IVUS) is a medical imaging modality aimed at imaging blood vessel walls from within the vessel. Current commercial IVUS catheters are designed to yield two-dimensional cross-sectional images perpendicular to the vessel wall. By pulling the catheter back through the artery (in the ‘axial direction’), and stacking the...
doctoral thesis 2012
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Van Dorp Schuitman, J. (author)
The acoustics of a concert hall, or any other room, are generally assessed by measuring room impulse responses for one or multiple source and receiver location(s). From these responses, objective parameters can be determined that should be related to various perceptual attributes of room acoustics. A set of these parameters is collected in ISO...
doctoral thesis 2011
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Melchior, F. (author)
Developments in the area of spatial sound reproduction have led to a large variety of established audio systems. Systems based on stereophonic principles are extended and growing from two channels via the ITU-R BS.775 surround setup to larger systems with more channels including elevated loudspeaker. On the other hand, sound field reproduction...
doctoral thesis 2011
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Chitu, D.A. (author)
The estimation of a velocity model is an important step in seismic imaging. To a large extend, seismic data interpretation is implicitly based on this model. Thus, the velocity model influences important conclusions such as size and shape of the reservoir and the expected volume of producible hydrocarbons. In the Common Focus Point (CFP)...
doctoral thesis 2011
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Dey, A.K. (author)
The Seismic Value Chain quantifies the cyclic interaction between seismic acquisition, imaging and reservoir characterization. Modern seismic innovation to address the global imbalance in hydrocarbon supply and demand requires such cyclic interaction of both feed-forward and feed-back processes. Currently, the seismic value chain paradigm is in...
doctoral thesis 2011
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Ghazali, A.R. (author)
A gas cloud is a region of gas accumulation in the subsurface, which can severely deteriorate the seismic data quality from deeper reflectors. Due to complex wave propagation through the anomaly and the resulting transmission imprint on the reflections from below this area, the image below the gas cloud is usually not properly recovered. The...
doctoral thesis 2011
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Hörchens, L. (author)
The detection of inhomogeneities in plates or plate-like structures constitutes a major problem in the field of non-destructive testing. For a few decades, classical techniques based on X-ray radiography have - as far as possible - been complemented and replaced by the usage of vibrations or acoustical waves due to the fact that these are less...
doctoral thesis 2010
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Przybysz-Jarnut, J.K. (author)
The numerical simulation of hydrocarbon reservoir flow is necessarily an approximation of the flow in the real reservoir. The knowledge about the reservoir is limited and some of the processes occurring are either not taken into account or not described in an adequate way. The parameters influencing the flow are usually not known, except in a...
doctoral thesis 2010
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Evers, L.G. (author)
Sound becomes inaudible if it consists of frequencies lower than 20 Hz, i.e. the human hearing threshold, and is called infrasound. Low frequency acoustic signals were first discovered after the eruption of the Krakatoa (Indonesia) in 1883. Due to its low frequency content, this infrasound traveled up to seven times around the globe while...
doctoral thesis 2008
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Pörtzgen, N. (author)
Ultrasonic non-destructive testing is a renowned method for the inspection of girth welds. However, defect sizing and characterization remains challenging with the current inspection philosophy. In addition, data display and interpretation is not straightforward and requires skill and experience from the inspector. A better and more reliable...
doctoral thesis 2007
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Van de Rijzen, M.J. (author)
The main subject of this thesis is the estimation of focusing operators, which are the kinematical part of the Green's function from reflector points in the subsurface, called focal points, to a grid of points located at the acquisition surface. This estimation process is data-driven and does not explicitly involve the estimation of a subsurface...
doctoral thesis 2007
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Tegtmeier, S. (author)
The purpose of a seismic survey is to produce an image of the subsurface providing an overview of the earth's discontinuities. The aim of seismic processing is to recreate this image. The seismic method is especially well suited for the exploration and the monitoring of hydrocarbon reservoirs. A majority of the algorithms, which are applied for...
doctoral thesis 2007
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Groen, J. (author)
In recent years, sonar performance has mainly improved via a significant increase in array ap-erture, signal bandwidth and computational power. This thesis aims at improving sonar array processing techniques based on these three steps forward. In applications such as anti-submarine warfare and mine hunting motion of the sonar needs to be...
doctoral thesis 2006
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Zwartjes, P.M. (author)
In seismic exploration an image of the subsurface is generated from seismic data through various data processing algorithms. When the data is not acquired on an equidistantly spaced grid, artifacts may result in the final image. Fourier reconstruction is an interpolation technique that can reduce these artifacts by generating uniformly sampled...
doctoral thesis 2005
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Cox, B.E. (author)
Seismic images of the structure of the earth are a prerequisite for finding new hydrocarbon reservoirs. The quality of a seismic images is highly dependent on the accuracy of the velocity model of the subsurface. Conventional imaging consists of an iterative process between obtaining the image using a velocity model, and updating this model by...
doctoral thesis 2004
Searched for: contributor:"Gisolf, A. (promotor)"
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