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Van der Grift, R.C. (author), Snellen, M. (author), Simons, D.G. (author)Accurate modelling of aircraft noise in different weather conditions is crucial for the reliability of noise predictions and their application worldwide. In best-practice aircraft noise models, such as Doc.29, the change in expected sound level on the ground due to changing atmosphere is modelled with a simplified propagation calculation. The...conference paper 2023
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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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VanDercreek, Colin (author), Merino Martinez, R. (author), Snellen, M. (author), Ragni, D. (author), Simons, D.G. (author)This paper analyses the influence of microphone cavity geometry on beamforming measurements with a turbulent boundary layer present on the microphone array. A 16- microphone array was tested in the anechoic open-jet wind tunnel of the Delft University of Technology. The array was placed on a flat plate mounted flush with the exit nozzle of the...conference paper 2020
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Amiri Simkooei, A. (author), Koop, L. (author), Snellen, M. (author), Simons, D.G. (author)In the last two decades, the use of multibeam echosounders has been growing for seafloor mapping and characterization. The former uses bathymetry data whereas the latter makes use of backscatter data. The use of backscatter data has been the subject of intensive research to gain insight into seafloor composition using either empirical or model...conference paper 2019
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Mohammadloo, Tannaz H. (author), Snellen, M. (author), Amiri Simkooei, A. (author), Simons, D.G. (author)Nowadays Multi-Beam Echo-Sounder (MBES) systems are used for obtaining information of the sea/river bed bathymetry and sediment composition. For the latter, use is usually made of the backscatter strength and depth derivatives, such as depth residuals. However, the depth derivatives are affected by the uncertainties inherent to the MBES varying...conference paper 2019
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Merino Martinez, R. (author), Pieren, R.D. (author), Snellen, M. (author), Simons, D.G. (author)Noise emissions from wind turbines are one of the main issues that the wind energy industry must deal with nowadays. Strict noise regulations often prevent wind turbines to operate at maximum power conditions, causing large losses of power production and, hence, of revenue. Several noise reduction measures have been proposed so far, but the...conference paper 2019
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Mohammadloo, Tannaz H. (author), Snellen, M. (author), Amiri Simkooei, A. (author), Simons, D.G. (author)Nowadays Multi-Beam Echo-Sounder (MBES) derived bathymetry is used for a large range of applications. However, these measurements are affected by the uncertainties inherent to the MBES. Since the development of the depth uncertainty prediction model, MBES systems have been improved noticeably. The present contribution addresses the importance of...conference paper 2019
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Merino Martinez, R. (author), Vieira, A.E. (author), Snellen, M. (author), Simons, D.G. (author)Aircraft noise is an increasingly important issue that causes annoyance and complaints for the communities living in the vicinity of airports. The conventional sound metrics (such as the A–weighted sound pressure level) typically used for assessing the impact of aircraft noise often fail to conveniently represent the actual annoyance...conference paper 2019
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Vieira, A.E. (author), Mehmood, Umair (author), Merino Martinez, R. (author), Snellen, M. (author), Simons, D.G. (author)The capacity of airports is limited due to the negative community response to noise. Traditional metrics, such as the A-weighted maximum sound pressure level (Lp;A;max), indicate the overall noise generated by an aircraft flyover but do not provide any information on tonal components or frequency variations in time that are known to affect...conference paper 2019
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VanDercreek, Colin (author), Sijtsma, P. (author), Snellen, M. (author), Ragni, D. (author), Avallone, F. (author), Simons, D.G. (author)A mathematical model is proposed that evaluates acoustic propagation of turbulent boundary layer waves on top of a cavity enclosing a microphone. The goal is to optimize these cavity geometries to improve the signal-to-noise ratio of acoustic measurements. This model predicts the attenuation of the turbulent boundary layer fluctuations...conference paper 2019
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Luesutthiviboon, S. (author), Malgoezar, A.M.N. (author), Snellen, M. (author), Sijtsma, P. (author), Simons, D.G. (author)Beamforming performance can be improved in two ways: optimizing the location of microphones on the acoustic array and applying advanced beamforming algorithms. In this study, the effects of the two approaches are studied. An optimization method is developed to optimize the location of microphones for an acoustic array used in an open-jet...conference paper 2018
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Vieira, A.E. (author), Malgoezar, A.M.N. (author), Snellen, M. (author), Simons, D.G. (author)The shielding of engine noise by the airframe of an aircraft is considered an effective way of reducing noise levels on the ground. Noise shielding in conventional aircraft is mainly due to the presence of the wings and most model predictions of full-scale aircraft neglect the effect of the airfoil curvature. The engine is typically simpliffied...conference paper 2018
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Merino Martinez, R. (author), Sanders, Martinus P.J. (author), Caldas, Luciano C. (author), Avallone, F. (author), Ragni, D. (author), de Santana, Leandro D. (author), Snellen, M. (author), Simons, D.G. (author)Microphone arrays are useful measurement devices for estimating the location and strength of sound sources. Numerous comparative studies have been conducted regarding the performance of acoustic imaging methods in the past, but literature lacks of a systematic investigation on the role of the hardware on the measurements. This research...conference paper 2018
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Merino Martinez, R. (author), Neri, Eleonora (author), Snellen, M. (author), Kennedy, John (author), Simons, D.G. (author), Bennett, Gareth J. (author)The noise emissions of a full-scale nose landing gear, measured in a wind tunnel and obtained from computational simulations, are compared with those of three regional aircraft types recorded in flyover measurements. The results from these three approaches are also compared with the predictions of two airframe noise models (Fink and Guo). The...conference paper 2018
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- Merino Martinez, R. (author), Neri, Eleonora (author), Snellen, M. (author), Kennedy, J (author), Simons, D.G. (author), Bennett, Gareth J. (author) conference paper 2017
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Mohammadloo, Tannaz H. (author), Tengku Ali, T.A. (author), Snellen, M. (author), Koop, L. (author), Gaida, T.C. (author), Simons, D.G. (author)Knowing the morphology and sediment composition of the seabed is of high importance for various applications. In this contribution, the repeatability of acoustic seafloor classification (ASC) results obtained from MBES backscatter value is investigated. The unsupervised classification algorithm based on Principal Component Analysis has been...conference paper 2017
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Mohammadloo, Tannaz H. (author), Snellen, M. (author), Simons, D.G. (author)The most recent generation multi-beam echosounders (MBES) allows to transmit Frequency Modulated (FM) signals, in addition to the more conventional Continuous Wave (CW) pulses. In this contribution, the effect of using these FM pulses for bathymetric measurements is investigated. Advantage of using FM signals is that measurements can be taken at...conference paper 2017
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- Mohammadloo, Tannaz H. (author), Snellen, M. (author), Simons, D.G. (author), Dierikx, Ben (author), Bicknese, Simon (author) conference paper 2017
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- Simons, D.G. (author), Snellen, M. (author), Merino Martinez, R. (author), Malgoezar, A.M.N. (author) conference paper 2017
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Vieira, A.E. (author), Snellen, M. (author), Simons, D.G. (author)The shielding of engine noise by the aircraft wings and fuselage can lead to a significant reduction on perceived noise on ground. Most research on noise shielding is focused on BlendedWing Body (BWB) configurations because of the large dimension of the fuselage. However, noise shielding is also considered relevant in conventional tube and...conference paper 2017