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Sonic assessment of physical ageing of plastic pipes

Makris, K. (author), Langeveld, J.G. (author), Clemens-Meyer, François H.L.R. (author), Watts, Joanna (author), Begum, Hasina (author), Horoshenkov, Kirill V. (author)

This article explores the potential of vibro-acoustics to detect physical ageing of plastic pipes. For this purpose, two different topics are combined: the ability of vibro-acoustics to estimate the storage modulus of a plastic pipe, and the sensitivity of the estimated storage modulus to changes due to ageing. Concerning the first topic, a...

journal article 2023

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Minimum-phase property and reconstruction of elastodynamic dereverberation matrix operators

Reinicke, Christian (author), Dukalski, Marcin (author), Wapenaar, C.P.A. (author)

Minimum-phase properties are well-understood for scalar functions where they can be used as physical constraint for phase reconstruction. Existing scalar applications of the latter in geophysics include, for example the reconstruction of transmission from acoustic reflection data, or multiple elimination via the augmented acoustic Marchenko...

journal article 2023

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Propagator and transfer matrices, Marchenko focusing functions and their mutual relations

Wapenaar, C.P.A. (author), Dukalski, Marcin (author), Reinicke, Christian (author), Snieder, Roel (author)

Many seismic imaging methods use wavefield extrapolation operators to redatum sources and receivers from the surface into the subsurface. We discuss wavefield extrapolation operators that account for internal multiple reflections, in particular propagator matrices, transfer matrices and Marchenko focusing functions. A propagator matrix is a...

journal article 2023

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Implementing Dynamic Boundary Conditions with the Material Point Method

Do, Phuong Chinh (author), Vardon, P.J. (author), Gonzalez Acosta, J.L. (author), Hicks, M.A. (author)

The material point method (MPM) is gaining an increasing amount of attention due to its capacity to solve geotechnical problems involving large deformations. Large deformations in geotechnics usually involve the failure process and therefore dynamic analyses are often carried out. However, simulating the (infinite) continuous domain using...

conference paper 2023

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Water-depth identification from free-surface data using the KdV-based nonlinear Fourier transform

de Koster, P.B.J. (author), Brühl, M. (author), Wahls, S. (author)

We propose a novel method to determine the average water depth from shallow, weakly nonlinear water waves that are approximated by the Korteweg-de Vries equation. Our identification method only requires free-surface measurements from two wave gauges aligned in the direction of wave propagation. The method we propose is based on comparing...

conference paper 2022

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Energy flux analysis for quantification of vibratory pile driving efficiency

Sánchez Gómez, S. (author), Tsetas, A. (author), Metrikine, A. (author)

In this paper, the energy flux in a pile modeled as an elastic shell, is studied theoretically and experimentally. Based on this analysis, a new procedure is proposed to quantify the pile installation efficiency. This procedure is of importance for vibratory installation of the foundations of offshore wind turbines and it is believed to be...

journal article 2022

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From wave speed to cardiac stiffness

Sabbadini, A. (author)

Diastolic heart failure is one of the principal causes of death in Western countries, and there is currently no treatment available; prevention, on the other hand, may be possible, provided an early enough diagnosis. The worsening of diastolic functionality is associated with increased values of cardiac stiffness, which could therefore provide a...

doctoral thesis 2021

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Comparisons between beam and continuum models for modelling wheel-rail impact at a singular rail surface defect

Shen, C. (author), Deng, X. (author), Wei, Z. (author), Dollevoet, R.P.B.J. (author), Zoeteman, A. (author), Li, Z. (author)

A singular rail or wheel surface irregularity, such as a squat, insulation joint or wheel flat, can cause large wheelrail impact force. Both the magnitude and frequency content of the impact force need to be correctly modelledbecause they are closely related to the formation, deterioration and detection of such irregularities. In this paper,we...

journal article 2021

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Vibration modes and wave propagation of the rail under fastening constraint

Zhang, P. (author), Li, S. (author), Nunez, Alfredo (author), Li, Z. (author)

This paper investigates three-dimensional (3D) rail vibrations under fastening constraint up to 5000 Hz and provides insights into rail vibration control by fastening parameters. A methodology is proposed, including experimental investigation and numerical simulations of rail vibrations. Three steps are considered: 1) experimental investigation...

journal article 2021

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Ultrasonic propagation in liquid and ice water drops. Effect of porosity

Mendonck, Michiel (author), Aparicio, Sofía (author), Díaz, Cristóbal González (author), Hernández, Margarita G. (author), Caro, Guillermo M.Muñoz (author), Anaya, José Javier (author), Cazaux, S.M. (author)

This work studies ultrasonic propagation in liquid and ice water drops. The effect of porosity on attenuation of ultrasonic waves in the drops is also explored. The motivation of this research was the possible application of ultrasonic techniques to the study of interstellar and com-etary ice analogs. These ice analogs, made by vapor...

journal article 2021

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Sensitivity analysis of generalised eigenproblems and application to wave and finite element models

Cicirello, A. (author), Mace, Brian (author), Kingan, Michael (author), Yang, Yi (author)

The first and second order sensitivity analysis of the eigenvalue problem of generalised, nonsymmetric matrices using perturbation theory is developed. These results are then applied to sensitivity analysis of wave propagation in structures modelled using the wave and finite element (WFE) method. Three formulations of the WFE eigenvalue problem...

journal article 2020

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Experiences with SWASH on modelling wave propagation over vegetation: Comparisons with lab and field data

Reis, Rui Almeida (author), Pires-Silva, António A. (author), Juana Fortes, Conceição (author), Suzuki, T. (author)

The vegetation capacity to protect the coasts from wave action is becoming more important and attractive due to ongoing sea level rise and increasing storminess. In addition, it is a quite environmentally friendly way. Quantifying the vegetation effect in wave propagation will be relevant for coastal management. A non-hydrostatic wave model...

journal article 2020

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Unified matrix-vector wave equation, reciprocity and representations

Wapenaar, C.P.A. (author)

The matrix-vector wave equation is a compact first-order differential equation. It was originally used for the analysis of elastodynamic plane waves in laterally invariant media. It has been extended by various authors for laterally varying media. Other authors derived a similar formalism for other wave phenomena. This paper starts with a...

journal article 2019

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Infrasound from the 2009 and 2017 DPRK rocket launches

Evers, L.G. (author), Assink, J. D. (author), Smets, P.S.M. (author)

Supersonic rockets generate low-frequency acoustic waves, that is, infrasound, during the launch and re-entry. Infrasound is routinely observed at infrasound arrays from the International Monitoring System, in place for the verification of the Comprehensive Nuclear-Test-Ban Treaty. Association and source identification are key elements of the...

journal article 2018

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Deep ocean sound speed characteristics passively derived from the ambient acoustic noise field

Evers, L.G. (author), Wapenaar, C.P.A. (author), Heaney, KD (author), Snellen, M. (author)

The propagation of acoustic waves in the ocean strongly depends on the temperature. Lowfrequency acoustic waves can penetrate the ocean down to depths where few in situ measurements are available. It is therefore attractive to obtain a measure of the deep ocean temperature from acoustic waves. The latter is especially true if the ambient...

journal article 2017

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Long-range correlations of microseism-band pressure fluctuations in the ocean

Ball, Justin S. (author), Godin, Oleg A. (author), Evers, L.G. (author), Lv, Cheng (author)

We investigate the spatial coherence of underwater ambient noise using a yearlong time-series measured off Ascension Island. Qualitative agreement with observed cross-correlations is achieved using a simple range-dependent model, constrained by earlier, active tomographic studies in the area. In particular, the model correctly predicts the...

journal article 2016

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Comparison of Eigenvectors for Coupled Seismo-Electromagnetic Layered-Earth Modeling

Grobbe, N. (author), Slob, E.C. (author), Thorbecke, J.W. (author)

We study the accuracy and numerical stability of three eigenvector sets for modelling the coupled poroelastic and electromagnetic layered-Earth response. We use a known eigenvector set, its flux-normalized version and a newly derived flux-normalized set. The new set is chosen such that the system is properly uncoupled when the coupling between...

journal article 2016

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Discretization effects in the finite element simulation of seismic waves in elastic and elastic-plastic media

Watanabe, Kohei (author), Pisano, F. (author), Jeremi, Boris (author)

Presented here is a numerical investigation that (re-)appraises standard rules for space/time discretization in seismic wave propagation analyses. Although the issue is almost off the table of research, situations are often encountered where (established) discretization criteria are not observed and inaccurate results possibly obtained. In...

journal article 2016

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Two-receiver measurements of phase velocity: cross-validation of ambient-noise and earthquake-based observations

Kästle, Emanuel D. (author), Soomro, Riaz (author), Weemstra, C. (author), Boschi, Lapo (author), Meier, Thomas (author)

Phase velocities derived from ambient-noise cross-correlation are compared with phase velocities calculated from cross-correlations of waveform recordings of teleseismic earthquakes whose epicentres are approximately on the station–station great circle. The comparison is conducted both for Rayleigh and Love waves using over 1000 station pairs in...

journal article 2016

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Combination of surface and borehole seismic data for robust target-oriented imaging

Liu, Yi (author), van der Neut, J.R. (author), Arntsen, B (author), Wapenaar, C.P.A. (author)

A novel application of seismic interferometry (SI) and Marchenko imaging using both surface and borehole data is presented. A series of redatuming schemes is proposed to combine both data sets for robust deep local imaging in the presence of velocity uncertainties. The redatuming schemes create a virtual acquisition geometry where both sources...

journal article 2016