Searched for: author:"Sijtsma, P."
(1 - 20 of 22)

Pages

document
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
document
Sijtsma, P. (author)
In this paper an accuracy criterion is derived for acoustic array measurements<br/>that are disturbed by incoherent noise, for example turbulent boundary layer noise<br/>in a wind tunnel. The accuracy criterion is a minimum signal-to-noise ratio at<br/>which the output of the array processing method has at least 95% likelihood of<br/>being...
conference paper 2020
document
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
document
van Dercreek, C.P. (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
document
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
document
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
document
Sijtsma, P. (author), Brouwer, Harry (author)
Unequally spaced transducer rings make it possible to extend the range of detectable azimuthal modes. The disadvantage is that the response of the mode detection algorithm to a single mode is distributed over all detectable modes, similarly to the Point Spread Function of Conventional Beamforming with microphone arrays. With multiple modes...
journal article 2018
document
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
document
Merino Martinez, R. (author), Sijtsma, P. (author), Snellen, M. (author)
Most acoustic imaging methods assume the presence of point sound sources and, hence, 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 source...
conference paper 2018
document
Sijtsma, P. (author)
This paper proposes a fast method for calculating the acoustic time delay between an observer and a receiver in a shear flow. This method is applied to an outdoor microphone array measurement on a large-scale wind turbine. In such a set-up, a shear flow represents the actual wind field better than a uniform flow. Steering vectors for beamforming...
conference paper 2018
document
Sijtsma, P. (author), Merino Martinez, R. (author), Malgoezar, A.M.N. (author), Snellen, M. (author)
In this article, a high-resolution extension of CLEAN-SC is proposed: high-resolution-CLEAN-SC. Where CLEAN-SC uses peak sources in ‘dirty maps’ to define so-called source components, high-resolution-CLEAN-SC takes advantage of the fact that source components can likewise be derived from points at some distance from the peak, as long as these...
journal article 2017
document
Sijtsma, P. (author), Merino Martinez, R. (author), Malgoezar, A.M.N. (author), Snellen, M. (author)
conference paper 2017
document
Sarradj, Ennes (author), Herold, Gert (author), Sijtsma, P. (author), Merino Martinez, R. (author), Malgoezar, A.M.N. (author), Snellen, M. (author), Geyer†, Thomas F. (author), Bahr, Christopher J. (author), Porteous„„, Ric (author), Moreau……, Danielle J. (author), Doolan, Con J. (author)
conference paper 2017
document
Tester, Brian J. (author), Sijtsma, P. (author)
Significant spectral broadening of tone noise by jet shear-layer turbulence can occur if the tone frequency and the path length through the shear layer are sufficiently large. A typical example of spectral broadening or ‘tone haystacking’ are turbine aero-engine tones which exhibit little or no haystacking when measured inside the engine but...
conference paper 2017
document
Malgoezar, A.M.N. (author), Snellen, M. (author), Sijtsma, P. (author), Simons, D.G. (author)
Assigning proper positions to microphones within arrays is essential in order to reduce or eliminate side- and grating lobes in 2D beamform images. In this paper an objective function is derived providing a measure for the presence of artificial sources. Using the global optimization method Differential Evolution an optimized microphone...
conference paper 2016
document
Sijtsma, P. (author), Snellen, M. (author)
In this paper a high-resolution extension of CLEAN-SC is proposed: HR-CLEAN-SC. Where CLEAN-SC uses peak sources in “dirty maps” to define so-called source components, HR-CLEAN-SC takes advantage of the fact that source components can likewise be derived from points at some distance from the peak, as long as these “source markers” are on the...
conference paper 2016
document
Malgoezar, A.M.N. (author), Snellen, M. (author), Simons, D.G. (author), Sijtsma, P. (author)
Conventional beamforming is a common method to localize sound sources with a microphone array. The method, which is based on the delay-and-sum beamforming, provides an estimate value for the source strength at a given spatial position. It suffers from low spatial resolution at low frequencies, high side lobe levels and requires the user to...
conference paper 2016
document
Tuinstra, M (author), Sijtsma, P (author)
conference paper 2015
document
van de Wal, H.M.M. (author), Sijtsma, P. (author)
The effects of winglet type "fences" at the outboard flap tip, and a blunt flap trailing edge on the airframe noise have been measured in a low-speed wind tunnel on a 8.5% half model. Both a single (extending downward) and a double type "fence" configuration (extending upward as well as downward from the wing) have been investigated. An airframe...
report 2001
document
Sijtsma, P. (author), Oerlemans, S. (author), Holthusen, H. (author)
A method is described for the location of moving sources by a microphone array. This method can be applied to out-of-flow measurements in an open jet wind tunnel. For that purpose, an expression is derived for the pressure field of a moving monopole in a uniform flow. It is argued that the open jet shear layer does not form a serious obstacle. A...
report 2001
Searched for: author:"Sijtsma, P."
(1 - 20 of 22)

Pages