scholarly journals Sensitivity of Ultrasonic Coda Wave Interferometry to Material Damage—Observations from a Virtual Concrete Lab

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4033
Author(s):  
Claudia Finger ◽  
Leslie Saydak ◽  
Giao Vu ◽  
Jithender J. Timothy ◽  
Günther Meschke ◽  
...  
Keyword(s):  
Elastic Moduli ◽  
Concrete Specimen ◽  
Coda Wave ◽  
Velocity Change ◽  
Damage Scenarios ◽  
Different Types ◽  
Source Signal ◽  
The Impact ◽  
Structural Scale ◽  
Coda Wave Interferometry

Ultrasonic measurements are used in civil engineering for structural health monitoring of concrete infrastructures. The late portion of the ultrasonic wavefield, the coda, is sensitive to small changes in the elastic moduli of the material. Coda Wave Interferometry (CWI) correlates these small changes in the coda with the wavefield recorded in intact, or unperturbed, concrete specimen to reveal the amount of velocity change that occurred. CWI has the potential to detect localized damages and global velocity reductions alike. In this study, the sensitivity of CWI to different types of concrete mesostructures and their damage levels is investigated numerically. Realistic numerical concrete models of concrete specimen are generated, and damage evolution is simulated using the discrete element method. In the virtual concrete lab, the simulated ultrasonic wavefield is propagated from one transducer using a realistic source signal and recorded at a second transducer. Different damage scenarios reveal a different slope in the decorrelation of waveforms with the observed reduction in velocities in the material. Finally, the impact and possible generalizations of the findings are discussed, and recommendations are given for a potential application of CWI in concrete at structural scale.

scholarly journals Sensitivity of Ultrasonic Coda Wave Interferometry to Material Damage - Observations from a Virtual Concrete Lab

2021 ◽  
Author(s):  
Claudia Finger ◽  
Leslie Saydak ◽  
Giao Vu ◽  
Jithender J. Timothy ◽  
Günther Meschke ◽  
...  
Keyword(s):  
Elastic Moduli ◽  
Concrete Specimen ◽  
Coda Wave ◽  
Velocity Change ◽  
Damage Scenarios ◽  
Different Types ◽  
Source Signal ◽  
The Impact ◽  
Structural Scale ◽  
Coda Wave Interferometry

Ultrasonic measurements are used in civil engineering for structural health monitoring of concrete infrastructures. The late portion of the ultrasonic wavefield, the coda, is sensitive to small changes in the elastic moduli of the material. Coda Wave Interferometry (CWI) correlates these small changes in the coda with the wavefield recorded in intact, or unperturbed, concrete specimen to reveal the amount of velocity change that occurred. CWI has the potential to detect localised damages and global velocity reductions alike. In this study, the sensitivity of CWI to different types of concrete mesostructures and their damage levels is investigated numerically. Realistic numerical concrete models of concrete specimen are generated and damage evolution is simulated using the discrete element method. In the virtual concrete lab, the simulated ultrasonic wavefield is propagated from one transducer using a realistic source signal and recorded at a second transducer. Different damage scenarios reveal a different slope in the decorrelation of waveforms with the observed reduction in velocities in the material. Finally, the impact and possible generalizations of the findings are discussed and recommendations are given for a potential application of CWI in concrete at structural scale.

scholarly journals A continuous record of intereruption velocity change at Mount St. Helens from coda wave interferometry

2014 ◽  
Vol 119 (3) ◽  
pp. 2199-2214 ◽  
Author(s):  
A. J. Hotovec‐Ellis ◽  
J. Gomberg ◽  
J. E. Vidale ◽  
K. C. Creager
Keyword(s):  
Coda Wave ◽  
Velocity Change ◽  
Continuous Record ◽  
Coda Wave Interferometry ◽  
Mount St Helens

Sensitivity kernels for coda-wave interferometry in a three-dimensional scalar scattering media

2020 ◽  
Author(s):  
Andres Barajas ◽  
Ludovic Margerin ◽  
Michel Campillo
Keyword(s):  
Free Surface ◽  
Surface Waves ◽  
Mixed Boundary ◽  
Surrounding Medium ◽  
Body Waves ◽  
Coda Waves ◽  
Coda Wave ◽  
Scattering Media ◽  
The Impact ◽  
Coda Wave Interferometry

<p>The ambient seismic noise has proven to be a powerful tool to assess velocity changes within the ground using coda-wave interferometry (CWI). CWI is based on the analysis of small waveform changes in the coda of the signals. Localizing and imaging the source that generates changes can be done with the help of sensitivity kernels which contain information on how each part of the surrounding medium contributes to the overall waveform perturbation that is recorded at a receiver. Although progress has been made in the theory of sensitivity kernels in the case of a full elastic space,  the inclusion of a free surface has proven to be difficult. Indeed, the free surface couples body waves and surface waves, which affects the sensitivity of coda waves with respect to the full-space case. Furthermore, one expects the depth sensitivity of coda waves to be strongly dependent on the relative contribution of surface and body waves, which depends on the lapse-time, source-receiver distance and scattering properties of the medium. Using the Monte-Carlo method, we compute traveltime-sensitivity kernels in a 3D scalar problem that includes body and surface waves, based on a recent theoretical model that integrates both through a mixed boundary condition. From these results, we assess the impact of the depth of a velocity perturbation on the recorded signals at the surface. Our results will be compared with previous numerical approaches from the literature. </p>

scholarly journals Locating microseismic sources with a single seismometer channel using coda wave interferometry

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. A19-A24 ◽  
Author(s):  
Youqian Zhao ◽  
Andrew Curtis ◽  
Brian Baptie
Keyword(s):  
Single Channel ◽  
Cost Effective ◽  
Coda Wave ◽  
Probabilistic Framework ◽  
Data Set ◽  
Cost Effective Method ◽  
Potential Applications ◽  
The Impact ◽  
Coda Wave Interferometry ◽  
Selection Of

A novel source location method based on coda wave interferometry (CWI) was applied to a microseismic data set of mining-induced events recorded in Nottinghamshire, England. CWI uses scattered waves in the coda of seismograms to estimate the differences between two seismic states. We used CWI to estimate the distances between pairs of earthquake locations, which are then used jointly to determine the relative location of a cluster of events using a probabilistic framework. We evaluated two improvements to this location technique: These account for the impact of a large difference in the dominant wavelength of a recording made on different instruments, and they standardize the selection of parameters to be used when implementing the method. Although the method has been shown to produce reasonable estimates on larger earthquakes, we tested the method for microseismic events with shorter distinguishable codas in recorded waveforms, and hence, fewer recorded scattered waves. The earthquake location results are highly consistent when using different individual seismometer channels, showing that it is possible to locate event clusters with a single-channel seismometer. We thus extend the potential applications of this cost-effective method to seismic events over a wider range of magnitudes.

scholarly journals Characterizing mechanical change in metals using amplitude-modulated diffuse ultrasound

2020 ◽  
Vol 19 (6) ◽  
pp. 1894-1904
Author(s):  
Fan Xie ◽  
Yuxiang Zhang ◽  
Eric Larose ◽  
Aroune Duclos ◽  
Su Chen ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Early Stage ◽  
Ultrasonic Method ◽  
Excitation Amplitude ◽  
Coda Wave ◽  
Metallic Materials ◽  
Velocity Change ◽  
Coda Wave Interferometry ◽  
Mechanical Change ◽  
Diffuse Ultrasound

In this article, we present an ultrasonic method based on diffuse ultrasound with successive excitation amplitudes. This method provides amplitude-dependent parameters of diffuse ultrasound using coda wave interferometry, and these parameters can be used to characterize mechanical change in metallic materials. The localized mechanical change caused by an instantaneous 400°C thermal shock in a meter-scale aluminum alloy slab was characterized by measuring the diffuse-wave velocity change and decorrelation coefficient as functions of the excitation amplitude. The potential mechanisms and spatial distribution that cause the observed amplitude-dependent diffuse waveform modification are discussed. Combining the method presented here with complementary approaches will enhance the ability to nondestructively detect early-stage damage in the laboratory or in the field.

scholarly journals Damage Detection at a Reinforced Concrete Specimen with Coda Wave Interferometry

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5013
Author(s):  
Stefan Grabke ◽  
Felix Clauß ◽  
Kai-Uwe Bletzinger ◽  
Mark Alexander Ahrens ◽  
Peter Mark ◽  
...  
Keyword(s):  
Inverse Problem ◽  
Reinforced Concrete ◽  
Damage Detection ◽  
Concrete Specimen ◽  
Bending Test ◽  
Coda Wave ◽  
Multiple Cracks ◽  
Ultrasonic Signals ◽  
Significant Difference ◽  
Coda Wave Interferometry

Reinforced concrete is a widely used construction material in the building industry. With the increasing age of structures and higher loads there is an immense demand for structural health monitoring of built infrastructure. Coda wave interferometry is a possible candidate for damage detection in concrete whose applicability is demonstrated in this study. The technology is based on a correlation evaluation of two ultrasonic signals. In this study, two ways of processing the correlation data for damage detection are compared. The coda wave measurement data are obtained from a four-point bending test at a reinforced concrete specimen that is also instrumented with fibre optic strain measurements. The used ultrasonic signals have a central frequency of 60 kHz which is a significant difference to previous studies. The experiment shows that the coda wave interferometry has a high sensitivity for developing cracks and by solving an inverse problem even multiple cracks can be distinguished. A further specialty of this study is the use of finite elements for solving a diffusion problem which is needed to state the previously mentioned inverse problem for damage localization.

Quota Women Are Threatening to Men

2017 ◽  
Vol 76 (3) ◽  
pp. 107-116 ◽  
Author(s):  
Klea Faniko ◽  
Till Burckhardt ◽  
Oriane Sarrasin ◽  
Fabio Lorenzi-Cioldi ◽  
Siri Øyslebø Sørensen ◽  
...  
Keyword(s):  
Decision Making ◽  
Organizational Performance ◽  
Gender Stereotypes ◽  
Perceived Threat ◽  
Preferential Treatment ◽  
Public Sector Employees ◽  
Different Types ◽  
Low Levels ◽  
Women In Decision Making ◽  
The Impact

Abstract. Two studies carried out among Albanian public-sector employees examined the impact of different types of affirmative action policies (AAPs) on (counter)stereotypical perceptions of women in decision-making positions. Study 1 (N = 178) revealed that participants – especially women – perceived women in decision-making positions as more masculine (i.e., agentic) than feminine (i.e., communal). Study 2 (N = 239) showed that different types of AA had different effects on the attribution of gender stereotypes to AAP beneficiaries: Women benefiting from a quota policy were perceived as being more communal than agentic, while those benefiting from weak preferential treatment were perceived as being more agentic than communal. Furthermore, we examined how the belief that AAPs threaten men’s access to decision-making positions influenced the attribution of these traits to AAP beneficiaries. The results showed that men who reported high levels of perceived threat, as compared to men who reported low levels of perceived threat, attributed more communal than agentic traits to the beneficiaries of quotas. These findings suggest that AAPs may have created a backlash against its beneficiaries by emphasizing gender-stereotypical or counterstereotypical traits. Thus, the framing of AAPs, for instance, as a matter of enhancing organizational performance, in the process of policy making and implementation, may be a crucial tool to countering potential backlash.

Situational Breakdowns

2019 ◽  
Author(s):  
Anne Nassauer
Keyword(s):  
United States ◽  
Large Scale ◽  
Contextual Factors ◽  
The United States ◽  
Social Outcomes ◽  
Dynamic Processes ◽  
Collective Decisions ◽  
Different Types ◽  
The Impact

This book provides an account of how and why routine interactions break down and how such situational breakdowns lead to protest violence and other types of surprising social outcomes. It takes a close-up look at the dynamic processes of how situations unfold and compares their role to that of motivations, strategies, and other contextual factors. The book discusses factors that can draw us into violent situations and describes how and why we make uncommon individual and collective decisions. Covering different types of surprise outcomes from protest marches and uprisings turning violent to robbers failing to rob a store at gunpoint, it shows how unfolding situations can override our motivations and strategies and how emotions and culture, as well as rational thinking, still play a part in these events. The first chapters study protest violence in Germany and the United States from 1960 until 2010, taking a detailed look at what happens between the start of a protest and the eruption of violence or its peaceful conclusion. They compare the impact of such dynamics to the role of police strategies and culture, protesters’ claims and violent motivations, the black bloc and agents provocateurs. The analysis shows how violence is triggered, what determines its intensity, and which measures can avoid its outbreak. The book explores whether we find similar situational patterns leading to surprising outcomes in other types of small- and large-scale events: uprisings turning violent, such as Ferguson in 2014 and Baltimore in 2015, and failed armed store robberies.

Monitoring medium changes in an intraplate setting with coda wave interferometry

2013 ◽  
Author(s):  
Virginie D'Hour ◽  
Aderson F. do Nascimento ◽  
Heleno C. de Lima Neto ◽  
Joaquim M. Ferreira ◽  
Martin Schimmel
Keyword(s):  
Coda Wave ◽  
Coda Wave Interferometry
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