The Experts below are selected from a list of 29736 Experts worldwide ranked by ideXlab platform
Shane Donohue - One of the best experts on this subject based on the ideXlab platform.
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characterization of norwegian marine clays with combined Shear Wave Velocity and piezocone cone penetration test cptu data
Canadian Geotechnical Journal, 2010Co-Authors: Michael Longm Long, Shane DonohueAbstract:A database of research-quality piezocone cone penetration test (CPTU) and Shear Wave Velocity, Vs, information for Norwegian marine clays has been assembled to study the small-strain stiffness rela...
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characterization of norwegian marine clays with combined Shear Wave Velocity and piezocone cone penetration test cptu data
Canadian Geotechnical Journal, 2010Co-Authors: Michael Longm Long, Shane DonohueAbstract:A database of research-quality piezocone cone penetration test (CPTU) and Shear Wave Velocity, Vs, information for Norwegian marine clays has been assembled to study the small-strain stiffness relationships for these materials and to examine the potential use of CPTU and Vs data in combination for the purposes of characterizing these soils. Data for sites where high-quality block sampling was carried out have mostly been used. Improvements have been suggested to existing correlations between the small-strain Shear modulus, Gmax, or Vs and index properties for these soils. Recent research has shown that CPTU corrected cone tip resistance, qt, and especially the pore pressure measured during CPTUs, u2, and Vs can be measured reliably and repeatably and are not operator or equipment dependant. Therefore, a new soil classification chart involving the normalized cone resistance, Qt, and normalized Shear Wave Velocity, Vs1, or Vs1 and Δu/σv0′ (where u is the pore-water pressure and σv0′ is the in situ vertical ...
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in situ Shear Wave Velocity from multichannel analysis of surface Waves masw tests at eight norwegian research sites
Canadian Geotechnical Journal, 2007Co-Authors: Michael Long, Shane DonohueAbstract:The multichannel analysis of surface Waves (MASW) technique, which is used to determine Shear Wave Velocity (Vs) and hence small strain stiffness (Gmax), has recently generated considerable interes...
Ernest L Madsen - One of the best experts on this subject based on the ideXlab platform.
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Shear Wave Velocity imaging using transient electrode perturbation phantom and ex vivo validation
IEEE Transactions on Medical Imaging, 2011Co-Authors: Ryan J Dewall, Tomy Varghese, Ernest L MadsenAbstract:This paper presents a new Shear Wave Velocity imaging technique to monitor radio-frequency and microWave ablation procedures, coined electrode vibration elastography. A piezoelectric actuator attached to an ablation needle is transiently vibrated to generate Shear Waves that are tracked at high frame rates. The time-to-peak algorithm is used to reconstruct the Shear Wave Velocity and thereby the Shear modulus variations. The feasibility of electrode vibration elastography is demonstrated using finite element models and ultrasound simulations, tissue-mimicking phantoms simulating fully (phantom 1) and partially ablated (phantom 2) regions, and an ex vivo bovine liver ablation experiment. In phantom experiments, good boundary delineation was observed. Shear Wave Velocity estimates were within 7% of mechanical measurements in phantom 1 and within 17% in phantom 2. Good boundary delineation was also demonstrated in the ex vivo experiment. The Shear Wave Velocity estimates inside the ablated region were higher than mechanical testing estimates, but estimates in the untreated tissue were within 20% of mechanical measurements. A comparison of electrode vibration elastography and electrode displacement elastography showed the complementary information that they can provide. Electrode vibration elastography shows promise as an imaging modality that provides ablation boundary delineation and quantitative information during ablation procedures.
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Shear Wave Velocity imaging using transient electrode perturbation a phantom study
Internaltional Ultrasonics Symposium, 2010Co-Authors: Ryan J Dewall, Tomy Varghese, Ernest L MadsenAbstract:A new Shear Wave Velocity imaging technique to monitor radiofrequency and microWave ablation procedures is presented, coined electrode vibration elastography. A piezoelectric actuator is attached to the ablation needle and is transiently vibrated to generate Shear Waves that are tracked at high frame rates. The time-to-peak algorithm is used to reconstruct the Shear Wave Velocity and thereby the Shear modulus variations. The feasibility of this approach is demonstrated in phantoms mimicking fully ablated (phantom 1) and partially ablated (phantom 2) regions. Shear Wave Velocity estimates in phantom 1 were within 7% of mechanical measurements and within 17% in phantom 2. Good boundary delineation was observed in both phantoms. No significant differences in ellipsoid area estimates between Shear Wave Velocity and B-mode images were present in phantom 1. Shear Wave Velocity area estimates were significantly higher than B-mode area estimates in phantom 2. Electrode vibration elastography shows promise as an imaging modality that provides ablation boundary delineation and quantitative information during ablation procedures.
Wenjong Chang - One of the best experts on this subject based on the ideXlab platform.
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1Characterization of Liquefaction Resistance in Gravelly Soil: Large Hammer Penetration Test and Shear Wave Velocity Approach
2015Co-Authors: Ping Sien Lin, Chi Wen Chang, Wenjong ChangAbstract:Gravelly soil is generally recognized to have no liquefaction potential. However, liquefaction cases are reported in central Taiwan in 1999 Chi-Chi Taiwan earthquake and in 1988 Armenia earthquake. Thus, further studies on the liquefaction potential of gravelly soil are warrent. Because large particles can impede the penetration of both SPT and CPT, Shear Wave Velocity based correlation and large Hammer Penetration Test (LPT) are employed to evaluate the liquefaction resistance of gravelly soils. A liquefied gravelly deposit site during the Chi-Chi earthquake was selected for this research. In situ physical properties of soil deposits are collected from exploratory trenches. Instrumented Large Hammer Penetration Test (LPT) and Shear Wave Velocity (Vs) measurements were performed to evaluate the liquefaction resistance. In addition, large-scale cyclic triaxial test on remolded gravelly soil samples (15 cm in diameter, 30 cm in height) were conducted to verify and improve LPT-based and Vs–based correlations. The results show that the Large Hammer Penetration Test and Shear Wave Velocity methods are reasonably suitable for liquefaction assessment of gravelly soils
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characterization of liquefaction resistance in gravelly soil large hammer penetration test and Shear Wave Velocity approach
Soil Dynamics and Earthquake Engineering, 2004Co-Authors: Ping Sien Lin, Chi Wen Chang, Wenjong ChangAbstract:Abstract Gravelly soil is generally recognized to have no liquefaction potential. However, liquefaction cases were reported in central Taiwan in the 1999 Chi-Chi Taiwan earthquake and in the 1988 Armenia earthquake. Thus, further studies on the liquefaction potential of gravelly soil are warranted. Because large particles can impede the penetration of both standard penetration test and cone penetration test, Shear Wave Velocity-based correlations and large hammer penetration tests (LPT) are employed to evaluate the liquefaction resistance of gravelly soils. A liquefied gravelly deposit site during the Chi-Chi earthquake was selected for this research. In situ physical properties of soil deposits were collected from exploratory trenches. Instrumented LPT and Shear Wave Velocity ( V s ) measurements were performed to evaluate the liquefaction resistance. In addition, large-scale cyclic triaxial tests on remolded gravelly soil samples (15 cm in diameter, 30 cm in height) were conducted to verify and improve LPT-based and V s -based correlations. The results show that the LPT and Shear Wave Velocity methods are reasonably suitable for liquefaction assessment of gravelly soils.
Howard J Patton - One of the best experts on this subject based on the ideXlab platform.
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broadband rayleigh Wave dispersion curve and Shear Wave Velocity structure for yucca flat nevada
Bulletin of the Seismological Society of America, 2012Co-Authors: Kimberly A Schramm, Robert E Abbott, Michael Asten, Susan L Bilek, A Pancha, Howard J PattonAbstract:The geology near a seismic source has a major effect on seismic Waves recorded at distance. This can be especially true in the case of man‐made explosions, due to increased geologic heterogeneity at shallow depths and interactions with the free surface. Yucca Flat (YF), a sedimentary basin on the Nevada National Security Site, has hosted hundreds of well‐recorded underground nuclear tests. As such, it should be an ideal natural laboratory for the study of shallow explosions. Unfortunately, basin‐wide models of such important physical properties as compressive‐ and Shear‐Wave Velocity are not available with sufficient fidelity to maximize the potential of the studies. We attempt to remedy this situation by creating a new Shear‐Wave Velocity model of YF. This model was generated by inverting Rayleigh‐Wave phase‐Velocity dispersion measurements. Because no single dataset provided a dispersion curve of the necessary frequency bandwidth for shallow, intermediate, and deep basin depths simultaneously, we combined three dispersion curves with complementary bandwidths from three data sources. The datasets, in order of low frequency to high, were (1) underground nuclear tests at YF, recorded on regional seismic networks (0.14–0.4 Hz); (2) a multimode spatially averaged coherency microtremor array located on YF (0.2–20 Hz); and (3) several refraction microtremor (ReMi) linear arrays, also on YF (2.5–50 Hz). Compared to previous work, our model is characterized by slower velocities. The known geologic boundaries such as the depth of the basin and water table are prominent at reasonable locations.
Ryan J Dewall - One of the best experts on this subject based on the ideXlab platform.
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Shear Wave Velocity imaging using transient electrode perturbation phantom and ex vivo validation
IEEE Transactions on Medical Imaging, 2011Co-Authors: Ryan J Dewall, Tomy Varghese, Ernest L MadsenAbstract:This paper presents a new Shear Wave Velocity imaging technique to monitor radio-frequency and microWave ablation procedures, coined electrode vibration elastography. A piezoelectric actuator attached to an ablation needle is transiently vibrated to generate Shear Waves that are tracked at high frame rates. The time-to-peak algorithm is used to reconstruct the Shear Wave Velocity and thereby the Shear modulus variations. The feasibility of electrode vibration elastography is demonstrated using finite element models and ultrasound simulations, tissue-mimicking phantoms simulating fully (phantom 1) and partially ablated (phantom 2) regions, and an ex vivo bovine liver ablation experiment. In phantom experiments, good boundary delineation was observed. Shear Wave Velocity estimates were within 7% of mechanical measurements in phantom 1 and within 17% in phantom 2. Good boundary delineation was also demonstrated in the ex vivo experiment. The Shear Wave Velocity estimates inside the ablated region were higher than mechanical testing estimates, but estimates in the untreated tissue were within 20% of mechanical measurements. A comparison of electrode vibration elastography and electrode displacement elastography showed the complementary information that they can provide. Electrode vibration elastography shows promise as an imaging modality that provides ablation boundary delineation and quantitative information during ablation procedures.
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Shear Wave Velocity imaging using transient electrode perturbation a phantom study
Internaltional Ultrasonics Symposium, 2010Co-Authors: Ryan J Dewall, Tomy Varghese, Ernest L MadsenAbstract:A new Shear Wave Velocity imaging technique to monitor radiofrequency and microWave ablation procedures is presented, coined electrode vibration elastography. A piezoelectric actuator is attached to the ablation needle and is transiently vibrated to generate Shear Waves that are tracked at high frame rates. The time-to-peak algorithm is used to reconstruct the Shear Wave Velocity and thereby the Shear modulus variations. The feasibility of this approach is demonstrated in phantoms mimicking fully ablated (phantom 1) and partially ablated (phantom 2) regions. Shear Wave Velocity estimates in phantom 1 were within 7% of mechanical measurements and within 17% in phantom 2. Good boundary delineation was observed in both phantoms. No significant differences in ellipsoid area estimates between Shear Wave Velocity and B-mode images were present in phantom 1. Shear Wave Velocity area estimates were significantly higher than B-mode area estimates in phantom 2. Electrode vibration elastography shows promise as an imaging modality that provides ablation boundary delineation and quantitative information during ablation procedures.