Searched for: subject%3A%22Acoustic%255C+imaging%22
(1 - 16 of 16)
document
van der Meulen, P.Q. (author)
Whereas aberrating layers are typically viewed as an impediment to medical ultrasound imaging, they can, surprisingly, also be used to our benefit. As long as we can model the effect of an aberrating layer, we can utilize ‘model-based imaging’, the imaging technique explored throughout this thesis, to reconstruct ultrasound images where...
doctoral thesis 2023
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von den Hoff, B. (author), Merino Martinez, R. (author), Simons, D.G. (author), Snellen, M. (author)
Complex acoustic systems typically present three-dimensional distributions of noise sources. Conventional acoustic imaging methods with planar microphone arrays are unsuitable for three-dimensional acoustic imaging, given the computational demands and the incapability to explicitly account for the presence of multiple sources. This paper...
journal article 2022
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von den Hoff, B. (author), Simons, D.G. (author), Snellen, M. (author)
Full-scale propeller measurements are useful to study the total noise contribution of a propeller-driven aircraft, including installation effects. Full-scale measurements under operational conditions also provide an accurate validation opportunity for propeller noise prediction models. These studies are, therefore, necessary to quantify and...
conference paper 2022
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Merino Martinez, R. (author), Kennedy, John (author), Bennett, Gareth J. (author)
The landing gear system is the dominant airframe noise source for most modern commercial aircraft during approach. This manuscript reports the results from the ALLEGRA (Advanced Low Noise Landing (Main and Nose) Gear for Regional Aircraft) project. This project assessed the performance of several highly realistic low–noise technologies (LNTs)...
journal article 2021
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Lima Pereira, L.T. (author), Merino Martinez, R. (author), Ragni, D. (author), Gómez-Ariza, David (author), Snellen, M. (author)
This paper explores the advantages of combining asynchronous microphone array measurements for acoustic source mapping in two and three–dimensional applications. Four different approaches are considered, three consisting of the combination of the source maps (arithmetic mean, geometric mean, and minimum value), and a fourth one obtained by...
journal article 2021
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Besnea, Irina (author)
With increasing UAV operations, tailored measures need to be implemented to integrate the massive employment of these vehicles in day-to-day operations. One of the current issues of UAVs is the noise emitted by these vehicles. The purpose of this research is to offer a doorway towards understanding the behavior of drone noise with changing...
master thesis 2020
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Merino Martinez, R. (author), Luesutthiviboon, S. (author), Zamponi, R. (author), Rubio Carpio, A. (author), Ragni, D. (author), Sijtsma, P. (author), Snellen, M. (author), Schram, Christophe (author)
In this paper, the performance of four acoustic imaging methods: conventional frequency domain beamforming (CFDBF), functional beamforming (FUNBF), enhanced high resolution CLEAN–SC (EHR–CLEAN–SC) and generalized inverse beamforming (GIBF), is investigated in terms of accuracy and variability. Three experimental test cases are considered: 1)...
journal article 2020
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von den Hoff, Bieke (author)
Over the past years, noise nuisance around airports strongly increased resulting in the need for aircraft noise reduction. Therefore, the noise sources should be known. This thesis assesses a new acoustic imaging method to identify sources on aircraft fly-over measurements. The proposed Global Optimisation (GO) algorithm is based on the theory...
master thesis 2020
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Merino Martinez, R. (author), Sijtsma, P. (author), Snellen, M. (author), Finez, A. (author), Herold, G. (author), Malgoezar, A.M.N. (author), Pereira, A. (author), Sarradj, E. (author), Simons, D.G. (author)
Phased microphone arrays have become a well-established tool for performing aeroacoustic measurements in wind tunnels (both open-jet and closed-section), flying aircraft, and engine test beds. This paper provides a review of the most well-known and state-of-the-art acoustic imaging methods and recommendations on when to use them. Several...
journal article 2019
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Luesutthiviboon, S. (author), Malgoezar, A.M.N. (author), Merino Martinez, R. (author), Snellen, M. (author), Sijtsma, P. (author), Simons, D.G. (author)
The recently introduced high-resolution (HR)-CLEAN-SC algorithm for acoustic imaging provides ‘super-resolution’, i.e. the ability to discern sound sources located closer than the Rayleigh resolution limit. This is achieved by allowing the source markers to be relocated from the actual source locations within a certain constraint to avoid the...
journal article 2019
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Merino Martinez, R. (author), Sijtsma, P. (author), Rubio Carpio, A. (author), Zamponi, R. (author), Luesutthiviboon, S. (author), Malgoezar, A.M.N. (author), Snellen, M. (author), Schram, Christophe (author), Simons, D.G. (author)
Most acoustic imaging methods assume the presence of point sound sources and, hence, may fail to correctly estimate the sound emissions of distributed sound sources, such as trailing-edge noise. In this contribution, three integration techniques are suggested to overcome this issue based on models considering a single point source, a line...
journal article 2019
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Merino Martinez, R. (author)
With the continuous growth in demand for air traffic and wind turbines, the noise emissions they generate are becoming an increasingly important issue. To reduce their noise levels, it is essential to obtain accurate information about all the sound sources present. Phased microphone arrays and acoustic imaging methods allow for the estimation of...
doctoral thesis 2018
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Nijhof, Daniëlle (author)
These are exciting times to work in the field of acoustics: researchers have a more granular understanding of sound than ever before due to the ability to acquire, store and analyze unprecedented amounts of acoustical data. The purpose of acoustic imaging is noise reduction. If noise can be measured, it can be reduced. Acoustic imaging is...
master thesis 2018
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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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Van Neer, P.L.M.J. (author), Danilouchkine, M.G. (author), Verweij, M.D. (author), Demi, L. (author), Voormolen, M.M. (author), Van der Steen, A.F.W. (author), De Jong, N. (author)
In medical ultrasound, fundamental imaging (FI) uses the reflected echoes from the same spectral band as that of the emitted pulse. The transmission frequency determines the trade-off between penetration depth and spatial resolution. Tissue harmonic imaging (THI) employs the second harmonic of the emitted frequency band to construct images....
journal article 2011
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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
Searched for: subject%3A%22Acoustic%255C+imaging%22
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