Search

Your search keyword '"Deckers, Elke"' showing total 148 results
Start Over Author "Deckers, Elke" Search Limiters Full Text
148 results on '"Deckers, Elke"'

1. Denoising of photogrammetric dummy head ear point clouds for individual Head-Related Transfer Functions computation

Author

Di Giusto, Fabio, Lluís, Francesc, van Ophem, Sjoerd, and Deckers, Elke

Subjects
Electrical Engineering and Systems Science - Audio and Speech Processing, Computer Science - Sound
Abstract

Individual Head-Related Transfer Functions (HRTFs), crucial for realistic virtual audio rendering, can be efficiently numerically computed from precise three-dimensional head and ear scans. While photogrammetry scanning is promising, it generally lacks accuracy, leading to HRTFs showing significant perceptual deviation from reference data, mainly due to scanning errors affecting the most occluded pinna structures. This paper examines the application of Deep Neural Networks (DNNs) for denoising photogrammetric ear scans. Several DNNs, fine-tuned on pinna samples corrupted with synthetic error modelled to mimic that observed in photogrammetric dummy head scans, are tested and benchmarked against a classical denoising method. One DNN is further modified and retrained to enhance its denoising performance. The comparison of HRTFs derived from original and denoised scans against reference data shows that the best-performing DNN marginally reduces the deviation of photogrammetric dummy head HRTFs to levels closer to accurately measured ones. Additionally, correlation analysis between geometric and HRTF metrics, computed on the scanned point clouds and their corresponding HRTFs, is used to identify key measures for evaluating the deviation between target and reference scans. These findings are expected to guide the selection of relevant loss functions and foster improvements in this and similar DNN models.

Published
2024

3. A guide to numerical dispersion curve calculations: explanation, interpretation and basic Matlab code

Author

Cool, Vanessa, Deckers, Elke, Van Belle, Lucas, and Claeys, Claus

Subjects
Physics - Applied Physics
Abstract

Dispersion diagrams play a crucial role in examining, analyzing and designing wave propagation in periodic structures. Despite their ubiquity and current research interest, introductory papers and reference scripting tailored to novel researchers in the field are lacking. This paper aims to address this gap, by presenting a comprehensive educational resource for researchers starting in the field of periodic structures and more specifically on the study of dispersion relations captured by dispersion surfaces or curves in dispersion diagrams. The objective is twofold. A first objective is to give a detailed explanation of dispersion diagrams, with graphical illustrations. Secondly, a documented Matlab code is provided to compute dispersion curves of 3D structures with 2D periodicity using the so-called inverse approach. These dispersion curves are obtained with numerical simulations using the finite element method. The code is written for elastic wave propagation and orthogonal periodicity directions, but can be extended to other types of linear wave propagation, non-orthogonal periodicity directions or 1D and 3D periodicity. The aim of this code is to serve as a starting point for novice researchers in the field, to facilitate their understanding of different aspects of dispersion diagrams and serve as a stepping stone in their future research., Comment: 43 pages, 23 figures

Published
2023
Full Text
View/download PDF

4. Time integration of finite element models with nonlinear frequency dependencies

Author

Deckers, Elke, Jonckheere, Stijn, and Meerbergen, Karl

Subjects
Mathematics - Numerical Analysis, 65F99, 65L99, G.1.3, G.1.10
Abstract

The analysis of sound and vibrations is often performed in the frequency domain, implying the assumption of steady-state behaviour and time-harmonic excitation. External excitations, however, may be transient rather than time-harmonic, requiring time-domain analysis. Some material properties, e.g.\ often used to represent for damping treatments, are still described in the frequency domain, which complicates simulation in time. In this paper, we present a method for the linearization of finite element models with nonlinear frequency dependencies. The linearization relies on the rational approximation of the finite element matrices by the AAA method. We introduce the Extended AAA method, which is classical AAA combined with a degree two polynomial term to capture the second order behaviour of the models. A filtering step is added for removing unstable poles.

Published
2022

11. Highly Efficient Energetic Synthesis of Coupled Steady-State Dynamic Systems

Author

Müller, Gerhard (Prof. Dr.), Müller, Gerhard (Prof. Dr. habil.);Deckers, Elke (Prof. Dr.), Ullmann, Rupert Ludwig Emanuel, Müller, Gerhard (Prof. Dr.), Müller, Gerhard (Prof. Dr. habil.);Deckers, Elke (Prof. Dr.), and Ullmann, Rupert Ludwig Emanuel

Abstract

A performative framework is developed for extensive parameter variations of vehicle vibroacoustic finite element models. It employs a fully modular, generalized domain coupling based on Newton iterations and parametric model order reduction using Krylov subspaces and a grid-free greedy search for a global basis. The framework enables a globalized optimization of a vehicle structure using a power-based objective. The performance of such an objective and methods for experimental power determination are discussed., Ein performantes Framework zur wiederholten Parametervariationen von vibroakustischen Finite Elemente Fahrzeugmodellen wird vorgestellt. Er basiert auf einer modularen, generalisierten Gebietskopplung mittels Newton-Iterationen, sowie parametrischer Modellreduktion durch Krylov Unterräume und netzfreier Greedy-Suche einer globalen Basis. Das Framework ermöglich die globalisierte Optimierung einer Fahrzeugstruktur bezüglich einer leistungsbasierten Zielfunktion. Deren Performanz und experimentelle Validierung werden diskutiert.

Published
2024

14. Analysis of laser scanning and photogrammetric scanning accuracy on the numerical determination of Head-Related Transfer Functions of a dummy head

Author

Di Giusto Fabio, van Ophem Sjoerd, Desmet Wim, and Deckers Elke

Subjects
head-related transfer functions, photogrammetry, boundary element method, binaural rendering, spatial sound localisation, Acoustics in engineering. Acoustical engineering, TA365-367, Acoustics. Sound, QC221-246
Abstract

Individual Head-Related Transfer Functions (HRTFs) are necessary for the accurate rendering of virtual scenes. However, their acquisition is challenging given the complex pinna shape. Numerical methods can be leveraged to compute HRTFs on meshes originating from precise scans of a subject. Although photogrammetry can be used for the scanning, its inaccuracy might affect the spatial cues of simulated HRTFs. This paper aims to assess the significance of the photogrammetric error affecting a Neumann KU100 dummy head scan. The geometrical differences between the photogrammetric scan and a laser scan are mainly located at the pinna cavities. The computed photogrammetric HRTFs, compared to measured and simulated data using objective and perceptually inspired metrics, show deviation in high frequency spectral features, stemming from the photogrammetric scanning error. This spectral deviation hinders the modelled elevation perception with photogrammetric HRTFs to levels comparable to renderings with nonindividual data. Extracting the photogrammetric geometry at individual ear cavities and merging it to the laser mesh, an assessment of the influence of the inaccuracy at different pinna structures is conducted. Correlation analysis between acoustic and geometrical metrics computed on the results is used to identify the most relevant geometrical metrics in relation to the HRTFs.

Published
2023
Full Text
View/download PDF

26. Efficient dispersion curve computations for periodic vibro-acoustic structures using the (generalized) Bloch mode synthesis

Author

Cool, Vanessa, Naets, Frank, Van Belle, Lucas, Desmet, Wim, and Deckers, Elke

Subjects
IOF, FM_affiliated, Mandaat_vanessa, PDmandaat_lucas
Abstract

Periodic structures such as metamaterials and phononic crystals hold potential as promising compact and lightweight solutions for noise and/or vibration attenuation in targeted frequency ranges. The performance of these structures is usually investigated by means of dispersion curves. The input for dispersion curve computations is often a finite element model of the corresponding unit cell. Nowadays, the vibration and noise attenuation of the periodic structures are generally tackled as separate problems and their performance is investigated with either structural or acoustic dispersion curves, respectively. Recently, vibro-acoustic unit cell models have come to the fore which can exhibit simultaneous structural and acoustic stopbands. However, the vibro-acoustic coupling inside the unit cell is usually not taken into account during the dispersion curve computations. To consider this coupling during their performance assessment, the computation of vibro-acoustic dispersion curves is required. Although these dispersion curves provide valuable information, the associated computational cost rapidly increases with unit cell model size. Model order reduction techniques are important enablers to overcome this high cost. In this work, the Bloch mode synthesis (BMS) and generalized BMS (GBMS) unit cell model order reduction techniques are extended to be applicable for 2D and 3D periodic vibro-acoustic systems. Through a verification case, the methodologies are shown to enable a strongly reduced dispersion curve calculation time while maintaining accurate predictions. At the time of verification: no ISSN/ISBN on the publisher's site. ispartof: Proceedings of ECCOMAS 2022 ispartof: ECCOMAS 2022, 8th European Congress on Computational Methods in Applied Sciences and Engineering location:Oslo, Norway date:5 Jun - 9 Jun 2022 status: published

Published
2022

33. On the impact of air in double-leaf panels with structural metamaterial cores

Author

Cool, Vanessa, Claeys, Claus, Van Belle, Lucas, Desmet, Wim, and Deckers, Elke

Subjects
IOF, FM_affiliated, Mandaat_vanessa, PDmandaat_lucas
Abstract

In the search for lightweight and compact partitions with both favorable vibro-acoustic characteristics and load-carrying capacity, an increasing trend towards double-leaf panels with structural metamaterial cores is emerging. Generally, these partitions are designed and analyzed by only considering the attenuation along the structural path, disregarding the influence of the air inside. This work investigates the impact of the air in these partitions on their performance, which reveals that the acoustic path needs to be included during the design phase. ispartof: pages:562-563 ispartof: Proceedings of META 2022 pages:562-563 ispartof: META 2022, the 12th International Conference on Metamaterials, Photonic crystals and Plasmonics location:Torremolinos, Spain date:19 Jul - 22 Jul 2022 status: Published online

Published
2022

34. The acoustic insulation performance of infinite and finite locally resonant metamaterial and phononic crystal plates

Author

Van Belle Lucas, Claeys Claus, Deckers Elke, and Desmet Wim

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

The bending wave stop band behavior of locally resonant metamaterial and phononic crystal plates can strongly improve the vibration performance of flexible plates in targeted frequency ranges. Their acoustic insulation performance, however, is found to strongly depend on the stop band mechanism, also influencing the frequency range of improvement. While sound transmission loss improvements are predicted for both infinite periodic plates, the finite phononic crystal plate performance can differ significantly.

Published
2019
Full Text
View/download PDF

38. Deep Learning for Photogrammetric Ear Point Clouds Denoising

Author

Di Giusto, Fabio, Lluís Salvadó, Francesc, van Ophem, Sjoerd, Desmet, Wim, and Deckers, Elke

Abstract

Individual Head Related Transfer Functions (HRTFs), necessary for the realistic audio rendering of a virtual scene, can be efficiently computed using numerical methods on three-dimensional scans of the ears and head of a subject. However, accurate geometries are required to obtain perceptually valid HRTFs. The most precise scanning techniques generally require specialized equipment, making them unpractical for a wide application. Photogrammetry, on the other hand, shows a great potential in terms of speed and affordability at the cost of a generally lower geometrical accuracy. The lack of precision of photogrammetric ear scans tends to significantly hinder the validity of the computed HRTFs. This is due to the complexity of the ear shape, generating a lack of visibility that negatively impacts the photogrammetric reconstruction algorithm, resulting in incomplete and noisy point clouds. This paper discusses the usage of deep neural networks for denoising and improving ear point clouds scanned through photogrammetry. Different neural network architectures are trained and tested on precise ear geometries to which artificial noise mimicking real photogrammetric error is applied. The results are compared to classical denoising approaches, and the validity of the HRTFs computed on the denoised scans is benchmarked against reference data. No ISBN/ISSN ispartof: pages:146-149 ispartof: Tagungsband der DAGA 2022 pages:146-149 ispartof: DAGA 2022 location:Stuttgart, Germany date:21 Mar - 24 Apr 2022 status: Published online

Published
2022

39. Impact of the unit cell choice on the efficiency of dispersion curve calculations using GBMS

Author

Cool, Vanessa, Van Belle, Lucas, Claeys, Claus, Deckers, Elke, and Desmet, Wim

Subjects
MOR4MDESIGN, Mandaat_Vanessa, IOF, PDmandaat_Lucas, FM_affiliated
Abstract

Recently, the potential of metamaterials and phononic crystals to cope with conflicting requirements of obtaining lightweight structures with desirable noise and vibration properties has been demonstrated. These, often periodic, structures are commonly studied based on their representative unit cell of which the vibro-acoustic performance is examined by means of their wave propagation, visualized by dispersion curves. Typically, the unit cell is discretized using a finite element technique to capture the possibly complex geometry. This leads to a high computation cost for the dispersion curve calculation which can be strongly reduced by applying modal based model order reduction techniques such as the (generalized) Bloch mode synthesis. In this paper, the choice of the unit cell is shown to have an impact on the dispersion curve calculation time. Moreover, the efficiency of (generalized) Bloch mode synthesis strongly depends on the unit cell choice. The highest reduction in computation time is accomplished when the number of boundary degrees-of-freedom is limited. ispartof: Journal of Vibration and Acoustics vol:144 issue:2 status: Published online

Published
2022

45. Cross-validation of acquisition methods for near-field Head-Related Transfer Functions with a high distance resolution

Author

Li, Yuqing, Di Giusto, Fabio, van Ophem, Sjoerd, Preihs, Stephan, Deckers, Elke, and Peissig, Jürgen

Subjects
eu-repo/grantAgreement/EC/H2020/812719 [VRACE - 812719, info]
Abstract

Due to the distance-dependent characteristics of near-field Head Related Transfer Functions (HRTFs), their acquisition procedure is much more complex than that of far-field HRTFs, which is already rather tedious. Recently, an approach to efficiently measure near-field HRTFs with a high distance resolution, using a continuously moving sound source and a Least Mean Square (LMS) adaptive filtering algorithm, has been proposed. Using this approach, we obtained a dataset containing horizontal plane HRTF data of a Neumann’s KU 100 dummy head for source distances from 19 cm to 119 cm with a spacing of 1 cm. Among the various choices for evaluation and validation, a direct comparison with another HRTF dataset is a straightforward solution. Since the distance resolution of all existing near-field HRTF databases is much lower than the one of interest, we numerically computed the HRTFs with the same spatial resolution using the laser-scanned surface geometry of the dummy head and the Finite Element Method (FEM). The aim of this work is to objectively evaluate the similarity and discrepancy between the two HRTF datasets in terms of spectral characteristics and perceptual effects. The causes of disparities between the datasets are discussed. ispartof: Proceedings of Meetings on Acoustics ispartof: Fourth Vienna Talk on Music Acoustics location:University of Music and Performing Arts, Vienna, Austria date:11 Sep - 14 Sep 2022 status: accepted

Published
2022
Full Text
View/download PDF

46. An accelerated deflation preconditioner for parametric systems based on subspace recycling

Author

Panagiotopoulos, Dionysios, Desmet, Wim, and Deckers, Elke

Abstract

Krylov subspace recycling [1] is often deployed to accelerate the iterative solution of sequences of linear systems. Such approaches reuse a continuously updated deflation subspace to reach a converged solution within a low number of iterations. This procedure is justified for problems that describe gradually evolving phenomena, such as crack propagation, and thus involve a sequence of systems that are not simultaneously available. However considering parametric systems, these techniques might induce an unnecessary overhead cost. Specifically, by constantly updating the recycled subspace a new projection on the newly constructed subspace needs to be operated for each new system, inducing a cost that scales with O( × N2) for dense systems, where N is the size of the system and is the size of the employed recycled basis. In that context, this work proposes an accelerated recycling procedure for parametric systems that is inspired by the Galerkin Model Order Reduction strategy and employs an offline ­ online operation splitting. In the offline part, the subspace to be recycled is constructed via an Automatic Krylov subspaces Recycling algorithm (AKR) [2] and the parametric system is projected on the subspace to yield a Reduced Order Model (ROM). Then, in the online part the construction of the deflation preconditioner only requires employing the ROM and as a result the cost of constructing the preconditioner is reduced to O(2). The proposed procedure is tested on a randomly parametrized linear system and is compared the non-deflated GMRES algorithm and a conventional recycling strategy presented in [11].

Published
2022
Full Text
View/download PDF

47. Non-destructive testing based on vibrations in the low to mid-frequency range

Author

Becht Philip, Deckers Elke, Claeys Claus, Pluymers Bert, and Desmet Wim

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

Recently, it has been shown that a Time Reversal MUltiple Signal Classification (TR-MUSIC) algorithm can be employed to detect defects in samples, which are both challenging in terms of material and in terms of geometrical complexity. This can be achieved by lowering the detection frequency as compared to most other TR and TR-MUSIC applications. In this case, the method operates in a low to mid-frequency range, where accurate models are still realizable. The method relies on the measurement of the frequency response function (FRF) between multiple excitation and sensor locations. These are gathered in a matrix, which then is decomposed in its singular vectors, serving as input for a MUSIC algorithm. In order to improve the applicability of this method, it is shown how to adapt the algorithm, in order to reduce the number of excitation locations or the number of sensors significantly. This results in a considerable speed-up for the application of this non-destructive testing strategy. Furthermore, it is investigated numerically how the robustness of the detection result under the influence of random measurement errors behaves if the number of excitation/sensor locations is reduced. Additionally, the dependency between, the decrease of the number of excitation/sensor locations and the types of defects, which can be detected is studied.

Published
2018
Full Text
View/download PDF

48. On the potential of injection moulding for the production of locally resonant metamaterials

Author

Steijvers, Kristof, Claeys, Claus, Desmet, Wim, Eyckens, Philip, Van Belle, Lucas, and Deckers, Elke

Subjects
IOF, FM_acknowledged, FM_affiliated, CAMEDO
Abstract

ispartof: pages:1-9 ispartof: Proceedings of the 26th International Congress of Mechanical Engineering pages:1-9 ispartof: COBEM 2021 26th International Congress of Mechanical Engineering location:Virtual Conference (Brazil) status: Published online

Published
2021

50. Cross-validation of acquisition methods for near-field Head-Related Transfer Functions with a high distance resolution.

Author

Yuqing Li, Di Giusto, Fabio, van Ophem, Sjoerd, Preihs, Stephan, Deckers, Elke, and Jürgen Peissig

Subjects
TRANSFER functions, FINITE element method, SURFACE geometry, AUDITORY scene analysis, SPATIAL resolution
Abstract

Due to the distance-dependent characteristics of near-field Head-Related Transfer Functions (HRTFs), their acquisition procedure is much more complex than that of far-field HRTFs, which is already rather tedious. Recently, an approach to efficiently measure near-field HRTFs with a high distance resolution using a continuously moving sound source and a Least Mean Square (LMS) adaptive filtering algorithm has been proposed. Using this approach, we obtained a dataset containing horizontal-plane HRTF data of a Neumann's KU 100 dummy head for source distances from 19cm to 119cm with a resolution of 1cm. Among the various choices for evaluation and validation, a direct comparison with another HRTF dataset is a straightforward solution. Since the distance resolution of all existing near-field HRTF databases is much lower than the one of interest, we numerically computed the HRTFs with the same spatial resolution using the laser-scanned surface geometry of the dummy head and the Finite Element Method (FEM). The aim of this work is to objectively evaluate the similarity and discrepancy between the two HRTF datasets in terms of spectral characteristics and perceptual effects. The causes of disparities between the datasets are discussed. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results