Changes in dielectric permittivity and shear wave velocity during concentration diffusion

SUMMARY Fluid injection for geothermal production has the potential to produce subsidence and microseismicity that can incur heavy financial cost or hazard. Due to this, novel ways to monitor subsurface deformation to supplement existing methods are highly sought after. We use seismic ambient noise to obtain time-dependent measurements of shear velocity within the geothermal reservoirs of Rotokawa and Ngatamariki, two producing geothermal fields in the Taupō Volcanic Zone located in the central North Island of New Zealand and operated by Mercury Energy. We investigate the relationship between shear wave velocity changes and geothermal injection by selecting time periods at the fields when injection and production volumes were significantly altered: 2009–2010 at Rotokawa, when geothermal injection was quadrupled due to the start-up of a new power station, and 2012–2013 at Ngatamariki, the beginning of geothermal injection for electricity production at that field. Shear wave velocity changes are computed from the ambient noise cross-correlation coda using the Moving Window Cross-Spectral (MWCS) technique, with a reference stack encompassing all data prior to the change in injection rate and moving stacks of 10–50 d. Gradual positive and negative shear velocity changes with a periodicity of approximately 12 months were observed at both sites, with maximum amplitude of 0.06 ± 0.04 and –0.08 ± 0.03 per cent at Rotokawa and 0.07 ± 0.03 and –0.06 ± 0.02 per cent at Ngatamariki. We hypothesize that these changes are due to seasonal rainfall, as seismic velocities computed by ambient noise are sensitive to the filling and emptying of near-surface pore space. In addition to these gradual responses, we found several sharp negative changes in velocity that reach minimum values over a few days and then gradually equilibrate to prior values over a few weeks. The amplitude of these responses is between –0.03 and –0.07 per cent and coincides with regional and local earthquakes. We hypothesize that these responses are primarily produced by the creation of new fractures, the same mechanism that produces gradual groundwater level decreases at regional distances from earthquake epicentres. We analyse a periodic signal within the time-delay measurements and determine that it is at least in part caused by the MWCS window size smoothing the cross-coherence of the ambient seismic signal. We do not observe shear wave velocity changes coinciding with geothermal injection, which may suggest that the signal has lower amplitude compared to the seasonal and seismic responses. We use bandstop filters and polynomial curve fitting to remove the contribution of the seasonal signal, but see no evidence of a shear wave velocity response due to geothermal fluid injection.

We investigated the relationship between intramuscular adipose tissue (IntraMAT) and muscle stiffness (passive and mechanical) and lengthening in young individuals, hypothesizing that (1) passive muscle stiffness is negatively correlated with the IntraMAT content, and (2) the IntraMAT content is negatively correlated with mechanical changes in muscle stiffness and fascicle length during passive dorsiflexion. Twenty men and women (20.3 ± 1.3years) participated in this study. Axial T1-weighted magnetic resonance imaging was performed at the thickest point of the medial gastrocnemius (MG) to measure the IntraMAT cross-sectional area (CSA) and muscle tissue CSA (units; cm2). The shear wave velocity (SWV) and fascicle length at the three ankle joint angles, namely 15° with plantarflexion (PF15), 0° with neutral position (NP), and 15° with dorsiflexion (DF15), were measured as parameters of muscle stiffness (unit; m/s) and lengthening (unit; cm) using ultrasound shear wave elastography and B-mode imaging. We further calculated the changes in SWV and fascicle length from PF15 to NP and from NP to DF15 as mechanical muscle stiffness and lengthening, respectively. There was a relationship between IntraMAT CSA and absolute SWV at DF15 (r = -0.47, P < 0.05). Further, a relationship was observed between IntraMAT CSA and change in SWV and fascicle length from NP to DF15 (r = -0.47 and r = 0.59, P < 0.05); whereas no relationship was observed between changes in fascicle length and muscle SWV (r = -0.23, P = 0.33). These results may indicate biomechanical and/or physiological associations between IntraMAT CSA and passive muscle stiffness.

Achilles tendon rupture (ATR) alters stiffness of the tendon and other structures within the triceps surae muscle-tendon unit. Although stiffness of the tendon has been studied after rupture, regional adaptations of the medial gastrocnemius (MG) muscle and aponeurosis mechanical properties are unknown. Therefore, we assessed changes in MG muscle and aponeurosis shear wave (SW) velocity and morphology during a 1-year follow-up after unilateral ATR. Twenty-three (17 males, 6 females) participants were assessed for SW velocity of MG muscle and aponeurosis and morphological properties at 2, 6 and 12months at rest. Linear mixed models were used to investigate the differences between limbs at different time points, and partial correlations controlled for age to explore associations between SW velocity and morphological properties. Regional SW stiffness of the injured MG muscle and aponeurosis were lower at 2months but recovered by 6months after ATR. When comparing limbs, MG muscle and aponeurosis SW velocity were lower in the injured limb at 2months with a mean difference of -0.34m/s (-0.48 to -0.21m/s, t=-5.10), and -1.6m/s (-2.39 to 0.89m/s, t=4.38). SW velocity did not differ at the muscle or aponeurosis between limbs at 6 or 12months. Fascicle length of the MG muscle was negatively correlated with SW velocity of the MG muscle (r=-0.25, p=0.041) and positively correlated with aponeurosis SW velocity (r=0.29, p=0.018). The remodelling of the MG muscle to shorter fascicles might help to enhance stiffness and maintain tension at the muscle.

Congruency of fatigue-mediated changes in shear wave velocity, upper limb force, muscle activity, and kinematics of the scapular stabilizer muscles.

Changes in dielectric permittivity and shear wave velocity during concentration diffusion : J. C. Santamarina & M. Fam, Canadian Geotechnical Journal, 32(4), 1995, pp 647–659

Isolating the effects of individual particle properties (e.g. shape, size, mineralogy, surface roughness) on the mechanical behavior of naturally occurring coarse-grained soils is a significant challenge in experimental studies. This challenge can be addressed by recent advances in 3D printing technology which enable generation of artificial sand-sized particles with independent control over particle size and shape. In this study, bender element tests are conducted to examine the isolated effects of particle shape on the shear wave velocity and shear modulus of 3D printed sand analogs. The experimental results show that the shear wave velocity and shear modulus of the 3D printed sand specimens exhibit a relationship with mean effective stress that is in agreement to that reported for natural sands. The specimens composed of 3D printed sands with greater particle roundness and sphericity exhibit greater shear wave velocity and shear modulus for a given void ratio, relative density, and mean effective stress. The changes in shear wave velocity can be captured in terms of differences in individual particle shape parameters such as roundness and sphericity as well as combined particle shape parameters such as regularity. Regression analysis is used to develop relationships between shear wave velocity and particle shape parameters and void ratio, which are shown to be in agreement with previously-published relationships and to reliably predict the shear wave velocity of natural sands. The results presented herein highlight the usefulness of testing 3D printed soils to identify functional trends and dependencies between soil response parameters and intrinsic properties. However, this requires verification of the results against published trends and assessment of the possible effects of the differences in constituent material between the 3D printed and the natural soils.

The effects of internal erosion on granular soils used in transport embankments

Section 1 Physical properties and laboratory measurements.- Shear waves in marine sediments-bridging the gap from theory to field applications (Opening paper).- Surface waves in poro-viscoelastic marine sediments.- An investigation of causality for Biot models by using Kramers-Kronig relations.- Soil properties for shear wave propagation (Invited).- The relevance of shear waves for structural subsurface investigations.- Experimental investigation of seismic surface waves in the seafloor.- Laboratory studies on pulsed leaky Rayleigh wave components in a water layer over a solid bottom.- Assessment of shear strength of the sea bottom from shear wave velocity measurements on box cores and in-situ.- Numerical modelling and laboratory experiments on underwater sound propagation over a shear supporting bottom.- A review of laboratory shear wave techniques and attenuation measurements with particular reference to the resonant column (Invited).- Relationship between acoustic and mechanical properties of two marine clays.- A laboratory method to investigate shear waves in a soft soil consolidating under self weight.- Laboratory measurements of acoustic properties of periplatform carbonate sediments.- Comparison of measured compressional and shear wave velocity values with predictions from Biot theory.- Wave velocities in sediments.- Shear wave attenuation in unconsolidated laboratory sediments.- Shear wave velocities of glacio-marine sediments: Barents Sea.- Rock acoustics: relevance of the porous viscoelastic model.- Influence of stress state and stress history on acoustic wave propagation in sedimentary rocks.- Section 2 Field experiments and interpretation.- A summary of DREA observations of interface waves at the seabed.- Observations of the relative contributions of waterborne and sediment paths to the received acoustic signal.- Shear-wave anisotropy in marine sediments around Britain from surface sources.- Refraction measurement of shear wave anisotropy in shallow marine sediments and implications for reflection processing.- Spatial variability in ground motion: effects of material heterogeneity in seafloor sediments.- Implications of deep-water seismometer array measurements for Scholte wave propagation.- Shear wave velocity structure from interface waves at two deep water sites in the Pacific ocean.- The effects of shear velocity structure on seafloor noise.- Concurrent observations of directional spectra of ocean surface waves and microseisms from an ocean subbottom seismometer (OSS) array.- Wave propagation in a borehole (Invited).- Application of shear wave measurements in boreholes.- Experience with the seismic cone penetrometer in offshore site Investigations.- Comparison of techniques for shear wave velocity and attenuation measurements.- Shear wave velocity gradients in near-surface marine sediment.- ISSAMS: an in situ sediment acoustic measurement system.- Small-scale in situ measurements of S-H velocity in surficial sedimentary deposits: localised textural and biological controls.- In situ measurements of shear-wave velocity in ocean sediments.- Seafloor shear wave velocity data acquisition: procedures and pitfalls.- Mapping of the sea bed via in situ shear wave (SH) velocities.- Observations of split shear-waves from young ocean crust.- Estimation of shear-wave speed in ocean-bottom sediments by comparing oblique-angle reflectivity measurements with normal incidence data.- SedimentQpfrom spectral ratios of converted shear reflections.- Constraints on shear velocities in deep-ocean sediments as determined from deep-tow multichannel seismic data.- Changes inPandSvelocities caused by subduction related sediment accretion off Washington/Oregon.- Compressional and shear wave velocities in the upper crust.- Sedimentary shear modulus and shear speed profiles from a gravity wave inversion.- Measurements of compressional wave and shear wave speeds, attenuation, permeability, and porosity in marine sediments.- Sea-bed shear moduli from measurements of tidally induced pore pressures.- Section 3 Modelling and inversion techniques.- Excess attenuation in low-frequency shallow-water acoustics: a shear wave effect? (Invited).- Sensitivity of bottom loss to attenuation and shear conversion.- The effect of shear wave attenuation on acoustic bottom loss resonance in marine sediments.- The influence of sediment rigidity on the plane-wave reflection coefficient.- Shear wave conversion due to subbottom facets.- A seismo-acoustic finite element model for underwater acoustic propagation.- Finite difference modelling of shear waves.- A stable higher-order elastic parabolic equation with application to Scholte wave propagation.- ELASTIC PE: a parabolic approximation for propagation modelling of shear wave effects in sediment layers.- Computation of shear waves by integral equations methods in stratified media.- Normal modes identification in shallow water using spectral analysis: theory and experiments.- Estimation of geoacoustic properties by inversion of acoustic field data (Invited).- A fast simulated annealing algorithm for the inversion of marine sediment seismo-acoustic parameters.- Determination of the sediment shear speed profiles from phase and group velocity dispersion data of SH wave.- Measurement of the elastic properties of the ocean bottom by inversion of reflection amplitude data.- Surface wave inversion for shear wave velocity (Invited).- Determination of shear velocity profiles by inversion of interface wave data.- Using synthetic seismograms to determine shear wave velocities in sediments from ocean bottom seismometer refraction observations.- Analytical investigation of seismic surface waves in the seafloor.- List of Participants.- Author Index.

Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Egyptian ministry of higher education and research Background Ultrafast echocardiography allows the direct non-invasive assessment myocardial shear waves (SW). These waves are naturally generated after mitral valve closure (MVC) and aortic valve closure (AVC) and their propagation velocities has been found to be linked to myocardial stiffness (MS) in adults. However, little experience exist regarding behaviour of such waves in children and normal values of SW velocities in children are lacking. Purpose This study aimed at setting up a reference range for SW velocities in paediatrics, determining influencing factors and exploring the reproducibility of their measurements in children. Methods One hundred-four healthy children (mean age 10 ±4 years old; range 2–18 years) were recruited. Participants were scanned with a research ultrasound scanner using divergent waves to yield a high frame rate of 1580 ±113 Hz. Parasternal long axis views (PLAX) were recorded for offline analysis. An anatomical M-mode was drawn along interventricular septum to visualize the propagation of shear waves after both MVC and AVC. Tissue Doppler acceleration maps were extracted and SW velocities were measured semi-automatically as the spatiotemporal slope of these waves (figure 1). Intra-class correlation coefficient (ICC) (2-way mixed model, absolute agreement between single measures) was used to check the reproducibility of these measurements among three raters. Results SW propagation velocities showed an association with clinical variables ; age (Figure2), body mass index (BMI) and body surface area (BSA). In addition, SW speeds showed association with local cardiac factors; ventricular septal thickness, LV mass and left ventricular end-systolic (LVESV) &amp; end-diastolic volumes (LVEDV). Using a multivariate model; predictors of SW velocities after MVC are: age and LV mass (R2=0.59), while predictors of SW after AVC are: age, LV mass and LV volumes (R2= 0.33). In twenty-five randomly selected participants, moderate to good inter-observer reliability were noted among the three observers (ICC 0.84 [CI 0.70 to 0.92] after MVC, and ICC 0.83 [CI 0.69 to 0.92] after AVC). Conclusions Naturally occurring myocardial shear waves in children can easily be measured with acceptable reproducibility. Values are lower than in adults. SW velocities in children showed clear dependency on age, presumably due to growing heart size and increased myocardial muscle mass.

Osteopathic assessment and osteopathic manipulative treatment (OMT) have been utilized in managing chronic neck pain (CNP) and neck somatic dysfunction. However, osteopathic assessments lack quantitative measures to detect muscle abnormalities and evaluate the effect ofOMT. This study aims to investigate the feasibility of utilizing ultrasound shear wave velocity (SWV) and shear wave relative anisotropy coefficient (SWRAC) to assess neck somatic dysfunction and the effect ofOMT. After receiving Institutional Review Board (IRB) approval and informed consent, we measured upper trapezius muscle (UTM) SWV in both longitudinal and transverse planes. We calculated SWRAC utilizing the formula: (SWV longitudinal-SWV transverse)/SWV transverse. We analyzed differences in muscle SWV and SWRAC between different age groups utilizing one-way analysis of variance (ANOVA). For the comparison in SWV and SWRAC between UTMs with and without neck somatic dysfunction, we utilized an unpaired t-test, although we examined the changes in SWV and SWRAC before and after OMT utilizing a paired t-test. We also evaluated correlations between SWV and muscle somatic dysfunction utilizing Spearman correlation. The diagnostic performance of SWV in identifying neck somatic dysfunction was assessed utilizing the area under receiver operating characteristic curve (AUC). Inter- and intra-observer reliability in measuring muscle SWV was analyzed utilizing intraclass correlation coefficient (ICC). From November 2022 to August 2024, we measured muscle SWV in 158 adults (68 men, 90 women, mean age 49years) without (51) and with (107) neck somatic dysfunction. We observed significant differences in SWV and SWRAC between UTMs with and without somatic dysfunction, and before and after OMT (p<0.01). Longitudinal muscle SWV was high in elderly subjects and thosewith neck somatic dysfunction. Longitudinal SWV positively correlated to neck somatic dysfunction (R 2=0.69). AUC of SWV for determining neck somatic dysfunction was 0.86. ICCs for measuring SWV ranged from 0.80 to0.99. The SWV in longitudinal muscles shows a positive correlation with neck somatic dysfunction, demonstrating moderate diagnostic accuracy and strong observer reliability. Application of OMT significantly decreases muscle stiffness measured by SWV, providing an objective and quantitative method to assess the effectiveness ofOMT.

Introduction. Deep soil mixing, that alters construction properties of foundations, allows to construct buildings and structures on the sites that have loose soils. As a rule, adverse geotechnical conditions are accompanied by dynamic forces that affect designed buildings and structures. The objective of these studies is to predict changes in mechanical properties of soils that follow the alteration of structural properties of a foundation. Soil cement is the focus of this study. Materials and methods. The findings of special laboratory tests of soil cement samples using the method of low amplitude torsional vibrations inside a resonant column in the anisotropic triaxial compression mode allowed to assess the effect of the supplementary vertical load on the velocity of shear elastic wave propagation. The co-authors present a description of the research method and provide an overview of the equipment used to conduct special laboratory tests. Tests were performed on undisturbed soil cement samples that had a natural water content. The anisotropic stress state of soil cement samples exposed to triaxial tests in the resonant column was caused by special behaviour features of the foundation. Results. In this study, laboratory tests had two stages. At the first stage, the effect of the vertical stress on the velocity of shear wave propagation was assessed. Correlation dependences between the shear wave velocity and the ratio of vertical and lateral stresses were obtained. At the second stage, shear wave propagation velocity values were identified at various combinations of lateral σ3 and vertical σ1 stresses. The results of the second stage are designated for the assessment of the effect of the anisotropic stress state and the projection of shear wave velocities at the stress levels anticipated on the site that will accommodate designed heavy structures. Conclusions. The findings allow to assess the effect of lateral and vertical stresses on changes of shear wave velocities in the triaxial compression mode. It was identified that at equal values of lateral stresses σ3, a 7-fold vertical stress σ1 increase leads to a 15 % increase in the shear wave velocity in soil cement Vs. At the same time, an increase in the ratio of vertical to lateral stresses σ1/σ3 by a factor of 15 causes an 11 % increase in the shear wave velocity. It is noted that the smaller the initial value of lateral stress σ3, the higher the rise in the shear wave velocity Vs in the course of testing. Correlation dependencies, presented in this study, can be used to assess the effect of the anisotropic state as the first approximation (for preliminary calculations) in the design of heavy structures on soil cement foundations.

Background Shear wave imaging (SWI) is a novel ultrasound technique based on the detection of transverse waves traveling through the myocardium using high frame rate echocardiography. These waves can be naturally induced e.g. by mitral valve closure (MVC). Their propagation velocity is dependent on the stiffness of the myocardium. Previous studies have shown the potential of SWI for the non-invasive assessment of myocardial stiffness. So far, the influence of loading on shear wave propagation velocities has not been extensively investigated. Purpose The aim of this study was to explore how loading changes affect shear wave propagation velocities after MVC. Methods Until now, 5 pigs (weight: 33.5±6.9 kg) were included. Echocardiographic images and left ventricular pressure recordings were simultaneously acquired during acute loading alterations: 1) preload was reduced by balloon occlusion of the vena cava inferior, 2) afterload was increased by balloon occlusion of the descending aorta and 3) preload was increased by intra-venous administration of 500 ml of saline. Left ventricular parasternal long-axis views were acquired with an experimental high frame rate ultrasound scanner (average frame rate: 1247±179 Hz). Shear waves were visualized on tissue acceleration maps by drawing an M-mode line along the interventricular septum. Shear wave propagation velocities after MVC were calculated by measuring the slope of the wave front on the acceleration maps (Figure A). Results The changes in left ventricular end-diastolic pressures (LV EDP) between baseline and each intervention are shown in Figure B. Preload reduction resulted in significantly reduced LV EDP (p&amp;lt;0.01). The shear wave propagation velocities after MVC dropped with preload reduction and increased significantly by increasing afterload as well as preload (both p&amp;lt;0.05) (Figure C). There was a good positive correlation between the change in LV EDP and the change in shear wave velocities (r=0.83; p&amp;lt;0.001) (Figure D). Conclusion The shear wave propagation velocity after MVC was significantly influenced by alterations in left ventricular loading conditions and changes in these velocities were related to changes in LV EDP. These results indicate that shear wave measurements at MVC might be a potential novel parameter for the estimation of left ventricular filling pressures. More pigs will be included in the future to further confirm these findings. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Fonds Wetenschappelijk Onderzoek - Vlaanderen

Conversion of building properties is performed primarily to reduce the compressibility of the base and increase strength. However, in addition to changing the static properties of soils, it is necessary to take into account changes in dynamic properties, such as dynamic shear modulus, damping coefficient, velocity of elastic shear and longitudinal waves. Thus, it is possible to control the dynamic properties of the base by converting the construction properties of soils. In this paper, we consider the change in the velocity of shear waves in a base transformed by the technology of deep soil mixing (DSM). In the work, the influence of additional vertical stresses on the dynamic properties of the bases transformed using deep soil mixing technology was evaluated. As a parameter that allowed us to evaluate the dynamic properties, the propagation velocity of elastic shear waves was chosen. Shear wave velocity was estimated based on the results of triaxial tests using the method of low-amplitude torsional vibrations in a resonant column. The research results showed that at small values of axial strains, there is no significant increase in the velocity of shear waves, an increase in the speed of shear waves by two times with an increase in stress by 0.6 MPa.

The resulting shear wave velocity profiles contain variations in absolute shear wave velocities, but more importantly, contain variations in the relative change in shear wave velocity between sands and shales. The relative changes in shear wave velocity produce significant variations in AVO response of reflections from sand/shale interfaces. The variation in AVO response is greatest for those model layers containing wet sands. The variation in AVO response is smaller for gas sands, as the AVO response is dominated by the decrease in the Poisson’ s ratio of the gas sands.

Effective techniques are currently available to obtain undisturbed samples of cohesive soils. However, little advance has been made in the procurement of undisturbed samples of cohesionless soils such as sands, silty sands, and clayey sands. In the area of earthquake design and liquefaction, researchers and practitioners are becoming increasingly aware of the importance of obtaining high-quality undisturbed samples of cohesionless soils. In situ ground-freezing techniques can be used to obtain undisturbed samples of cohesionless soils. However, there is still concern regarding the possibility of disturbance during the freezing and thawing of the samples. Shear wave velocity is a direct measurement of the stiffness of the soil skeleton at small strains (&lt;10−4%). Hence, shear wave velocity can be a sensitive measurement to detect changes in void ratio and soil structure due to freezing and thawing. A laboratory study has been performed to evaluate the use of shear wave velocity measurements to detect sample disturbance due to freezing and thawing of cohesionless soils. Samples prepared with different amounts and type of fines were frozen using uniaxial freezing techniques and subsequently thawed. Shear wave velocity measurements were made before and after freezing and thawing of the reconstituted samples. The measured shear wave velocities were unchanged for samples that did not heave (undisturbed) during the freeze–thaw cycle. Samples that heaved (disturbed) showed an associated change in shear wave velocity. Hence, measurements of shear wave velocities in situ and in the laboratory have the potential to identify sample disturbance in granular soils. Key words : in situ, sampling, freezing, disturbance, shear wave velocity.