Liquefaction assessment based on strain energy is significantly superior to conventional stress-based methods.The main purpose of the present study is to investigate the correlation between shear wave velocity and str...Liquefaction assessment based on strain energy is significantly superior to conventional stress-based methods.The main purpose of the present study is to investigate the correlation between shear wave velocity and strain energy capacity of silty sands.The dissipated energy until liquefaction occurs was calculated by analyzing the results of three series of comprehensive cyclic direct simple shear and triaxial tests on Ottawa F65,Nevada,and Firoozkuh sands with varying silt content by weight and relative densities.Additionally,the shear wave velocity of each series was obtained using bender element or resonant column tests.Consequently,for the first time,a liquefaction triggering criterion,relating to effective overburden normalized liquefaction capacity energy(WL=s’c)to effective overburden stresscorrected shear wave velocity(eVs1)has been introduced.The accuracy of the proposed criteria was evaluated using in situ data.The results confirm the ability of shear wave velocity as a distinguishing parameter for separating liquefied and non-liquefied soils when it is calculated against liquefaction capacity energy(WL=s’c).However,the proposed WL=s’c-Vs1 curve,similar to previously proposed cyclic resistance ratio(CRR)-Vs1 relationships,should be used conservatively for fields vulnerable to liquefaction-induced lateral spreading.展开更多
We assembled approximately 328 seismic records. The data set was from 4 digitally recording long-period and broadband stations of CDSN. We carried out the inversion based on the partitioned waveform inversion (PWI). I...We assembled approximately 328 seismic records. The data set was from 4 digitally recording long-period and broadband stations of CDSN. We carried out the inversion based on the partitioned waveform inversion (PWI). It partitions the large-scale optimization problem into a number of independent small-scale problems. We adopted surface waveform inversion with an equal block (2((2() discretization in order to acquire the images of shear velocity structure at different depths (from surface to 430 km) in the crust and upper-mantle. The resolution of all these anomalies has been established with (check-board( resolution tests. These results show significant difference in velocity, lithosphere and asthenosphere structure between South China Sea and its adjacent regions.展开更多
AIM To explore the relationship of liver and spleen shear wave velocity in patients with liver cirrhosis combined with portal hypertension,and assess the value of liver and spleen shear wave velocity in predicting the...AIM To explore the relationship of liver and spleen shear wave velocity in patients with liver cirrhosis combined with portal hypertension,and assess the value of liver and spleen shear wave velocity in predicting the prognosis of patients with portal hypertension.METHODS All 67 patients with liver cirrhosis diagnosed as portal hypertension by hepatic venous pressure gradient in our hospital from June 2014 to December 2014 were enrolled into this study. The baseline information of these patients was recorded. Furthermore,67 patients were followed-up at 20 mo after treatment,and liver and spleen shear wave velocity were measured by acoustic radiation force impulse at the 1^(st) week,3^(rd) month and 9^(th) month after treatment. Patients with favorable prognosis were assigned into the favorable prognosis group,while patients with unfavorable prognosis were assigned into the unfavorable prognosis group. The variation and difference in liver and spleen shear wave velocity in these two groups were analyzed by repeated measurement analysis of variance. Meanwhile,in order to evaluate the effect of liver and spleen shear wave velocity on the prognosis of patients with portal hypertension,Cox's proportional hazard regression model analysis was applied. The ability of those factors in predicting the prognosis of patients with portal hypertension was calculated through receiver operating characteristic(ROC) curves.RESULTS The liver and spleen shear wave velocity in the favorable prognosis group revealed a clear decline,while those in the unfavorable prognosis group revealed an increasing tendency at different time points. Furthermore,liver and spleen shear wave velocity was higher in the unfavorable prognosis group,compared with the favorable prognosis group; the differences were statistically significant(P < 0.05). The prognosis of patients with portal hypertension was significantly affected by spleen hardness at the 3^(rd) month after treatment [relative risk(RR) = 3.481]. At the 9^(th) month after treatment,the prognosis was affected by liver hardness(RR = 5.241) and spleen hardness(RR = 7.829). The differences between these two groups were statistically significant(P < 0.05). The ROC analysis revealed that the area under the curve(AUC) of spleen hardness at the 3^(rd) month after treatment was 0.644,while the AUCs of liver and spleen hardness at the 9^(th) month were 0.579 and 0.776,respectively. These might predict the prognosis of patients with portal hypertension.CONCLUSION Spleen hardness at the 3^(rd) month and liver and spleen shear wave velocity at the 9^(th) month may be used to assess the prognosis of patients with portal hypertension. This is hoped to be used as an indicator of predicting the prognosis of patients with portal hypertension.展开更多
Accurate shear wave velocity is very important for seismic inversion.However,few researches in the shear wave velocity in organic shale have been carried out so far.In order to analyze the structure of organic shale a...Accurate shear wave velocity is very important for seismic inversion.However,few researches in the shear wave velocity in organic shale have been carried out so far.In order to analyze the structure of organic shale and predict the shear wave velocity,the authors propose two methods based on petrophysical model and BP neural network respectively,to calculate shear wave velocity.For the method based on petrophysics model,the authors discuss the pore structure and the space taken by kerogen to construct a petrophysical model of the shale,and establish the quantitative relationship between the P-wave and S-wave velocities of shale and physical parameters such as pore aspect ratio,porosity and density.The best estimation of pore aspect ratio can be obtained by minimizing the error between the predictions and the actual measurements of the P-wave velocity.The optimal porosity aspect ratio and the shear wave velocity are predicted.For the BP neural network method that applying BP neural network to the shear wave prediction,the relationship between the physical properties of the shale and the elastic parameters is obtained by training the BP neural network,and the P-wave and S-wave velocities are predicted from the reservoir parameters based on the trained relationship.The above two methods were tested by using actual logging data of the shale reservoirs in the Jiaoshiba area of Sichuan Province.The predicted shear wave velocities of the two methods match well with the actual shear wave velocities,indicating that these two methods are effective in predicting shear wave velocity.展开更多
A large number of Rayleigh wave dispersion curves recorded at twenty three seismic stations was used to investigate the 3-D shear wave velocity structure of the northeastern Brazilian lithosphere. A simple procedure t...A large number of Rayleigh wave dispersion curves recorded at twenty three seismic stations was used to investigate the 3-D shear wave velocity structure of the northeastern Brazilian lithosphere. A simple procedure to generate a three-dimensional image of Mohorovicic;discontinuity was applied in northeastern Brazil and the Moho 3-D image was in agreement with several isolated crustal thicknesses obtained with different geophysical methods. A detailed 3-D S wave velocity model is proposed for the region. In the crust, our model is more realist than CRUST2.0 global model, because it shows more details either laterally or in depth than global model, i.e., clear lateral variation and gradual increase of S wave velocity in depth. Down to 100 km depth, the 3-D S wave velocity model in northeastern Brazil is dominated by low velocities and this is consistent either with heat flow measurements or with measurements of the flexural strength of the lithosphere developed in the South American continent. Our 3-D S wave velocity model was also used to obtain the lithosphere thickness in each cell of the northeastern Brazil and the results were consistent with global studies about the Lithosphere-Asthenosphere Boundary worldwide.展开更多
Shear wave velocity has numerous applications in geomechanical, petrophysical and geophysical studies of hydrocarbon reserves. However, data related to shear wave velocity isn’t available for all wells, especially ol...Shear wave velocity has numerous applications in geomechanical, petrophysical and geophysical studies of hydrocarbon reserves. However, data related to shear wave velocity isn’t available for all wells, especially old wells and it is very important to estimate this parameter using other well logging. Hence, lots of methods have been developed to estimate these data using other available information of reservoir. In this study, after processing and removing inappropriate petrophysical data, we estimated petrophysical properties affecting shear wave velocity of the reservoir and statistical methods were used to establish relationship between effective petrophysical properties and shear wave velocity. To predict (VS), first we used empirical relationships and then multivariate regression methods and neural networks were used. Multiple regression method is a powerful method that uses correlation between available information and desired parameter. Using this method, we can identify parameters affecting estimation of shear wave velocity. Neural networks can also be trained quickly and present a stable model for predicting shear wave velocity. For this reason, this method is known as “dynamic regression” compared with multiple regression. Neural network used in this study is not like a black box because we have used the results of multiple regression that can easily modify prediction of shear wave velocity through appropriate combination of data. The same information that was intended for multiple regression was used as input in neural networks, and shear wave velocity was obtained using compressional wave velocity and well logging data (neutron, density, gamma and deep resistivity) in carbonate rocks. The results show that methods applied in this carbonate reservoir was successful, so that shear wave velocity was predicted with about 92 and 95 percents of correlation coefficient in multiple regression and neural network method, respectively. Therefore, we propose using these methods to estimate shear wave velocity in wells without this parameter.展开更多
Soil shear wave velocity （SWV） is an important parameter in geotechnical engineering. To measure the soil SWV, three methods are generally used in China, including the single-hole method, cross-hole method and the s...Soil shear wave velocity （SWV） is an important parameter in geotechnical engineering. To measure the soil SWV, three methods are generally used in China, including the single-hole method, cross-hole method and the surface-wave technique. An optimized approach based on a correlation function for single-hole SWV measurement is presented in this paper. In this approach, inherent inconsistencies of the artificial methods such as negative velocities, and too-large and too-small velocities, are eliminated from the single-hole method, and the efficiency of data processing is improved. In addition, verification using the cross-hole method of upper measuring points shows that the proposed optimized approach yields high precision in signal processing.展开更多
Objective The aim of this study was to evaluate the additional benefit of the difference of maximum and minimum shear wave velocity(SWV) values obtained at different probe orientations(D-value) for the differential di...Objective The aim of this study was to evaluate the additional benefit of the difference of maximum and minimum shear wave velocity(SWV) values obtained at different probe orientations(D-value) for the differential diagnosis of breast tumors.Methods SWV(m/s) was measured in 123 breast tumors(92 benign,31 malignant) in 76 female patients with the probe placed on the transverse,longitudinal,and 45° planes.The areas under the receiver operating characteristic(AUROC) curves were compared with respect to the maximum SWV,minimum SWV,D-value,maximum SWV combined with the D-value,and minimum SWV combined with the D-value.Results There was a significant difference among the values of the maximum SWV,minimum SWV,and D-value for the 3 planes(P < 0.001).The AUROC curves for the maximum SWV,minimum SWV,and D-values of the 3 planes were 0.751(P = 0.379),0.486(P = 0.863),and 0.603(P = 0.204),respectively.The cutoff value for the maximum SWV for differentiating benign tumors from malignant tumors was 2.51 m/s(sensitivity 67%,specificity 50%).The cutoff value for the minimum SWV was 1.61 m/s(sensitivity 53%,specificity 50%).Adding the D-value increased the AUROC curve for the maximum SWV from 0.571 to 0.733 and the minimum SWV from 0.486 to 0.504(P = 0.964),respectively.Conclusion SWV differs in different planes of breast tumors.The D-value can provide a reference for the differential diagnosis of breast tumors.展开更多
BACKGROUND Several studies have demonstrated the feasibility and effectiveness of using ultrasound elastography to assess liver tissue stiffness.Virtual touch imaging quantification(VTIQ)based on acoustic radiation fo...BACKGROUND Several studies have demonstrated the feasibility and effectiveness of using ultrasound elastography to assess liver tissue stiffness.Virtual touch imaging quantification(VTIQ)based on acoustic radiation force impulse imaging has been developed as a latest and noninvasive method for assessing liver stiffness in children.AIM To determine the standard value in healthy children,and to identify possible factors that might influence the VTIQ measurement.METHODS With the ethical approval,202 children between 1 month and 15 years old were included in this study.None of them had any liver or systematic diseases.All children had a normal ultrasound scan and normal body mass index(BMI)range.The subjects were divided into four age and BMI groups.The effects of gender,age,liver lobe,measurement depth,and BMI on liver elasticity were investigated.RESULTS A significant correlation was found between age and shear wave velocity(SWV)value.At measurement depths of 1.5 cm and 2.0 cm in the left lobe,there were significant differences among the age groups.SWV values were significantly negatively correlated with the measurement depth.Gender,liver lobe,and BMI showed no significant effect on the SWV values.Age and BMI may influence the quality of the elastogram.CONCLUSION VTIQ is a noninvasive technique that is feasible to measure liver stiffness in children.The afore-mentioned velocity value obtained utilizing VTIQ method could be used as reference value for normal liver stiffness in children.展开更多
The bender element testing features its in-plane directivity, which allows using bender elements to measure the shear wave velocities in a wider range of in-plane configurations besides the standard tip-to-tip alignme...The bender element testing features its in-plane directivity, which allows using bender elements to measure the shear wave velocities in a wider range of in-plane configurations besides the standard tip-to-tip alignment. This paper proposed a novel bender element testing technique for measuring the horizontal shear wave velocity of soils, where the bender elements are surface- mounted and the axes of the source and receiver elements are parallel to each other. The preliminary tests performed on model ground of silica sand showed that, by properly determining the travel distance and time of the shear waves, the surface-mounted bender elements can perform as accurately as the conventional "tip-to-tip" configuration. Potentially, the present system provides a promising nondestructive tool for characterizing geomaterials and site conditions both in laboratory and in the fields.展开更多
The correlations between shear wave velocity(SWV)calculated from virtual touch tissue imaging quantification(VTIQ)technique and histological prognostic factors of invasive ductal carcinoma was investigated.A total of ...The correlations between shear wave velocity(SWV)calculated from virtual touch tissue imaging quantification(VTIQ)technique and histological prognostic factors of invasive ductal carcinoma was investigated.A total of 76 breast tumors histologically confirmed as invasive ductal carcinomas were included in this study.SWV values were measured by VTIQ for each lesion preoperatively or prior to breast biopsy.The maximum values were recorded for statistical analysis.Medical records were reviewed to determine tumor size,histological grade,lymph node status and immunohistochemical results.Tumor subtypes were categorized as luminal A,luminal B,human epidermal growth factor receptor 2(HER2)positive and triple negative.The correlations between SWV and histological prognostic factors were analyzed.It was found that tumor size showed positive association with SWV(r=0.465,P<0.001).Larger tumors had significantly higher SWV than smaller ones(P=0.001).Histological grade 1 tumors had significantly lower SWV values than those with higher histological grade(P=0.015).The Ki67 expression,tumor subtypes and lymph node status showed no statistically significant correlations with SWV,although triple negative tumors and lymph node-positive tumors showed higher SWV values.It was concluded that tumor size was significantly associated with SWV.Higher histological grade was associated with increased SWV.There was no statistically significant correlations between SWV and other histological prognostic factors.展开更多
This article presents a case study concerning a seismic characterization project.Full-wave sonic logging was used to characterize the shallow compressional wave and shear wave velocity profiles in the site.Anomalous v...This article presents a case study concerning a seismic characterization project.Full-wave sonic logging was used to characterize the shallow compressional wave and shear wave velocity profiles in the site.Anomalous values of the Poisson’s ratio derived from the velocity profiles suggested that the boreholes might have traversed slow formations(i.e.with shear wave velocity smaller than the borehole fluid compressional wave velocity or“mud-wave speed”)and that conventional processing of the sonic logs might have misinterpreted the direct arrivals of fluid acoustic waves as arrivals caused by shear wave propagation in the rock.Consequently,the shear wave velocity profiles provided by the contractor were considered to be unreliable by the project team.To address these problems,a non-conventional determination of the shear wave velocity was implemented,based on the relationship between the Poisson’s ratio of the rock formation and the shape of the first train of sonic waves which arrived to the receivers in the sonic probe.The relationship was determined based on several hundreds of finite element simulations of the acoustic wave propagation in boreholes with the same diameter as used in the perforations.The present article describes how this non-conventional approach was developed and implemented to obtain the shear wave velocity profiles from the raw sonic logs.The approach allows an extension of the range of applicability of full-wave sonic logging to determination of shear wave velocity profiles in formations with low compressional wave velocities.The method could be used to obtain shear wave velocity profiles where compressional wave velocity is as low as slightly larger than the mud-wave speed.A sample sonic log in Log ASCII Standard(LAS)format is provided as supplementary material to this paper via Mendeley Data,together with the FORTRAN source code used to process the log following the approach described in this study.展开更多
The main purpose of current study is development of an intelligent model for estimation of shear wave velocity in limestone. Shear wave velocity is one of the most important rock dynamic parameters. Because rocks have...The main purpose of current study is development of an intelligent model for estimation of shear wave velocity in limestone. Shear wave velocity is one of the most important rock dynamic parameters. Because rocks have complicated structure, direct determination of this parameter takes time, spends expenditure and requires accuracy. On the other hand, there are no precise equations for indirect determination of it; most of them are empirical. By using data sets of several dams of Iran and neuro-genetic, adaptive neuro-fuzzy inference system （ANFIS）, and gene expression programming （GEP） methods, models are rendered for prediction of shear wave velocity in limestone. Totally, 516 sets of data has been used for modeling. From these data sets, 413 ones have been utilized for building the intelligent model, and 103 have been used for their performance evaluation. Compressional wave velocity （Vp）, density （7） and porosity （.n）, were considered as input parameters. Respectively, the amount of R for neuro-genetic and ANFIS networks was 0.959 and 0.963. In addition, by using GEP, three equations are obtained; the best of them has 0.958R. ANFIS shows the best prediction results, whereas GEP indicates proper equations. Because these equations have accuracy, they could be used for prediction of shear wave velocity for limestone in the future.展开更多
Objective: To study the differential value of shear wave velocity (SWV) in nodules quantitatively determined by acoustic radiation force impulse (ARFI) for benign and malignant thyroid nodules. Methods: Patients who w...Objective: To study the differential value of shear wave velocity (SWV) in nodules quantitatively determined by acoustic radiation force impulse (ARFI) for benign and malignant thyroid nodules. Methods: Patients who were diagnosed with thyroid nodules in the People's Hospital of Hai'an County between June 2014 and February 2017 were selected and divided into those with benign thyroid nodules and malignant thyroid nodules according to the biopsy results. Before biopsy, the ARFI ultrasonic elastography was performed to measure SWV, and the biopsy tissue was collected after biopsy to determine the expression of proliferation molecules and invasion molecules. Results: The SWV of malignant thyroid nodules was significantly higher than that of benign thyroid nodules;P53, CyclinG2, E-cadherin, TIMP1 and TIMP3 mRNA expression in malignant thyroid nodules were significantly lower than those in benign thyroid nodules while FOXA1, Survivin, XIAP, Twist and Vimentin mRNA expression were significantly higher than those in benign thyroid nodules;P53, CyclinG2, E-cadherin, TIMP1 and TIMP3 mRNA expression in malignant thyroid nodules with high SWV were significantly lower than those in malignant thyroid nodules with low SWV while FOXA1, Survivin, XIAP, Twist and Vimentin mRNA expression were significantly higher than those in malignant thyroid nodules with low SWV. Conclusion: The SWV of malignant thyroid nodules significantly increases and is closely related to the abnormal proliferation and invasion of cancer cells.展开更多
Objective:To discuss the relationship of ultrasonic shear wave velocity (SWV) with oncogene and tumor suppressor gene expression in primary liver cancer lesions as well as angiogenesis factor contents.Methods:100 pati...Objective:To discuss the relationship of ultrasonic shear wave velocity (SWV) with oncogene and tumor suppressor gene expression in primary liver cancer lesions as well as angiogenesis factor contents.Methods:100 patients with primary liver cancer who underwent surgical treatment in our hospital between March 2014 and September 2016 were collected as observation group, and 50 healthy subjects who received physical examination in our hospital during the same period were collected as normal control group. The ultrasonic SWV levels of two groups of subjects were measured before the operation, and the observation groups were further divided into high SWV group and low SWV group, 50 cases in each group. Intraoperative tumor tissue samples were kept and fluorescence quantitative PCR was used to determine the mRNA expression of oncogenes and tumor suppressor genes. Enzyme-linked immunosorbent assay was used to determine serum contents of angiogenesis factors in observation group before operation.Results:Hepatic ultrasonic SWV level in observation group was significantly higher than that in normal control group;proto-oncogene CK, Ki67, Gly-3, Survivin and Pokemon mRNA expression in tumor tissue of high SWV group were higher than those of low SWV group while tumor suppressor genes Tg737, p16, p27, PTEN and runx3 mRNA expression were lower than those of low SWV group;serum angiogenesis factors VEGF, MMP-9 and IGF-1R contents were higher than those in low SWV group. Conclusion: The hepatic ultrasonic SWV level increases in patients with primary liver cancer, and the SWV level is directly correlated with oncogene and tumor suppressor gene expression as well as angiogenesis factor contents.展开更多
Shear wave elastography(SWE)is now becoming an indispensable diagnostic tool in the routine examination of liver diseases.In particular,accuracy is required for shear wave propagation velocity measurement,which is dir...Shear wave elastography(SWE)is now becoming an indispensable diagnostic tool in the routine examination of liver diseases.In particular,accuracy is required for shear wave propagation velocity measurement,which is directly related to diagnostic accuracy.It is generally accepted that the liver shear wave propagation velocity reflects the degree of fibrosis,but there are still few reports on other factors that increase the shear wave propagation velocity.In this study,we reviewed such factors in the literature and examined their mechanisms.Current SWE measures propagation velocity based on the assumption that the medium has a homogeneous structure,uniform density,and is purely elastic.Otherwise,the measurement is subject to error.The other(confounding)factors that we routinely experience are primarily:(1)Conditions that appear to increase the viscous component;and(2)Conditions that appear to increase tissue density.Clinically,the former includes acute hepatitis,congested liver,biliary obstruction,etc,and the latter includes diffuse infiltration of malignant cells,various storage diseases,tissue necrosis,etc.In any case,it is important to evaluate SWE in the context of the entire clinical picture.展开更多
Recent studies using field case history data yielded new criteria for evaluating liquefaction potential in saturated granular deposits based on in situ, stress-corrected shear wave velocity. However, the conditions of...Recent studies using field case history data yielded new criteria for evaluating liquefaction potential in saturated granular deposits based on in situ, stress-corrected shear wave velocity. However, the conditions of relatively insufficient case histories and limited site conditions in this approach call for additional data to more reliably define liquefaction resistance as a function of shear wave velocity. In this study, a series of undrained cyclic triaxial tests were conducted on saturated sand with shear wave velocity Vs measured by bender element. By normalizing the data with respect to minimum void ratio, the test results, in-corporated with previously published laboratory data, statistically revealed good correlation of cyclic shear strength with small-strain shear modulus for sandy soils, which is almost irrespective of soil types and confining pressures. The consequently determined cyclic resistance ratio, CRR, was found to be approximately proportional to Vs4. Liquefaction resistance boundary curves were established by applying this relationship and compared to liquefaction criteria derived from seismic field measure-ments. Although in the range of Vs1>200 m/s the presented curves are moderately conservative, they are remarkably consistent with the published field performance criteria on the whole.展开更多
The crustal structure in Myanmar can provide valuable information for the eastern margin of the ongoing IndoEurasian collision system.We successively performed H-k stacking of the receiver function and joint inversion...The crustal structure in Myanmar can provide valuable information for the eastern margin of the ongoing IndoEurasian collision system.We successively performed H-k stacking of the receiver function and joint inversion of the receiver function and surface wave dispersion to invert the crustal thickness(H),shear wave velocity(V_(S)),and the V_(P)/V_(S) ratio(k)beneath nine permanent seismic stations in Myanmar.H was found to increase from 26 km in the south and east of the study area to 51 km in the north and west,and the V_(P)/V_(S) ratio was complex and high.Striking differences in the crust were observed for different tectonic areas.In the Indo-Burma Range,the thick crust(H~51 km)and lower velocities may be related to the accretionary wedge from the Indian Plate.In the Central Myanmar Basin,the thin crust(H=26.9-35.5 km)and complex V_(P)/V_(S) ratio and V_(S) suggest extensional tectonics.In the Eastern Shan Plateau,the relatively thick crust and normal V_(P)/V_(S) ratio are consistent with its location along the western edge of the rigid Sunda Block.展开更多
This research aims at improving the methods of prediction of shear wave velocity in underground layers. We propose and showcase our methodology using a case study on the Mashhad plain in north eastern part of Iran. Ge...This research aims at improving the methods of prediction of shear wave velocity in underground layers. We propose and showcase our methodology using a case study on the Mashhad plain in north eastern part of Iran. Geotechnical investigations had previously reported nine measurements of the SASW (Spectral Analysis of Surface Waves) method over this field and above wells which have DHT (Down Hole Test) result. Since SASW utilizes an analytical formula (which suffers from some simplicities and noise) for evaluating shear wave velocity, we use the results of SASW in a trained artificial neural network (ANN) to estimate the un- known nonlinear relationships between SASW results and those obtained by the method of DHT (treated here as real values). Our results show that an appropriately trained neural network can reliably predict the shear wave velocity between wells accurately.展开更多
Shear wave velocity Vs is measured by the surface geophysical survey like MASW （multi-channel surface wave analysis） or RWM （refraction wave method） and by the subsurface method like PS logging. PS logging and RWM...Shear wave velocity Vs is measured by the surface geophysical survey like MASW （multi-channel surface wave analysis） or RWM （refraction wave method） and by the subsurface method like PS logging. PS logging and RWM are direct methods to derive shear wave velocity and MASW retrieves shear wave through the inversion of the surface wave. In this work, the effectiveness of surface methods （MASW and RWM） is compared with PS logging in determining shear wave velocity. For this purpose, shear wave velocity results Vs30 of 12 PS logging and MASW surveys conducted in Mymensingh Municipality in Bangladesh have been utilized. Additionally, the shear wave velocity results of three PS logging have been compared with the refraction profiles of RWM survey conducted in Rooppur nuclear power plant site in Bangladesh. The relative discrepancy between RWM and PS logging is found less （ranges from -3.92 to 0.93） compared to MASW and PS logging （＋/-0.88 to 33.92）. The correlation coefficient of Vs30 derived from RWM and PS logging is observed much better （0.60） compared to MASW and PS logging （0.40）. The result is good considering the lateral lithologic variability and inherent differences among techniques. It is evident from the comparison that the RWM can be used as a cost-effective alternative to traditional borehole PS logging method for Vs30 determination and thus the number of down-hole logging tests might be significantly reduced.展开更多
文摘Liquefaction assessment based on strain energy is significantly superior to conventional stress-based methods.The main purpose of the present study is to investigate the correlation between shear wave velocity and strain energy capacity of silty sands.The dissipated energy until liquefaction occurs was calculated by analyzing the results of three series of comprehensive cyclic direct simple shear and triaxial tests on Ottawa F65,Nevada,and Firoozkuh sands with varying silt content by weight and relative densities.Additionally,the shear wave velocity of each series was obtained using bender element or resonant column tests.Consequently,for the first time,a liquefaction triggering criterion,relating to effective overburden normalized liquefaction capacity energy(WL=s’c)to effective overburden stresscorrected shear wave velocity(eVs1)has been introduced.The accuracy of the proposed criteria was evaluated using in situ data.The results confirm the ability of shear wave velocity as a distinguishing parameter for separating liquefied and non-liquefied soils when it is calculated against liquefaction capacity energy(WL=s’c).However,the proposed WL=s’c-Vs1 curve,similar to previously proposed cyclic resistance ratio(CRR)-Vs1 relationships,should be used conservatively for fields vulnerable to liquefaction-induced lateral spreading.
基金State Natural Scientific Foundation (49734150) and National High Performance Computation Foundation.
文摘We assembled approximately 328 seismic records. The data set was from 4 digitally recording long-period and broadband stations of CDSN. We carried out the inversion based on the partitioned waveform inversion (PWI). It partitions the large-scale optimization problem into a number of independent small-scale problems. We adopted surface waveform inversion with an equal block (2((2() discretization in order to acquire the images of shear velocity structure at different depths (from surface to 430 km) in the crust and upper-mantle. The resolution of all these anomalies has been established with (check-board( resolution tests. These results show significant difference in velocity, lithosphere and asthenosphere structure between South China Sea and its adjacent regions.
基金Supported by Medical and Health Science and Technology Program of Zhejiang Province,2017,No.2017KY590
文摘AIM To explore the relationship of liver and spleen shear wave velocity in patients with liver cirrhosis combined with portal hypertension,and assess the value of liver and spleen shear wave velocity in predicting the prognosis of patients with portal hypertension.METHODS All 67 patients with liver cirrhosis diagnosed as portal hypertension by hepatic venous pressure gradient in our hospital from June 2014 to December 2014 were enrolled into this study. The baseline information of these patients was recorded. Furthermore,67 patients were followed-up at 20 mo after treatment,and liver and spleen shear wave velocity were measured by acoustic radiation force impulse at the 1^(st) week,3^(rd) month and 9^(th) month after treatment. Patients with favorable prognosis were assigned into the favorable prognosis group,while patients with unfavorable prognosis were assigned into the unfavorable prognosis group. The variation and difference in liver and spleen shear wave velocity in these two groups were analyzed by repeated measurement analysis of variance. Meanwhile,in order to evaluate the effect of liver and spleen shear wave velocity on the prognosis of patients with portal hypertension,Cox's proportional hazard regression model analysis was applied. The ability of those factors in predicting the prognosis of patients with portal hypertension was calculated through receiver operating characteristic(ROC) curves.RESULTS The liver and spleen shear wave velocity in the favorable prognosis group revealed a clear decline,while those in the unfavorable prognosis group revealed an increasing tendency at different time points. Furthermore,liver and spleen shear wave velocity was higher in the unfavorable prognosis group,compared with the favorable prognosis group; the differences were statistically significant(P < 0.05). The prognosis of patients with portal hypertension was significantly affected by spleen hardness at the 3^(rd) month after treatment [relative risk(RR) = 3.481]. At the 9^(th) month after treatment,the prognosis was affected by liver hardness(RR = 5.241) and spleen hardness(RR = 7.829). The differences between these two groups were statistically significant(P < 0.05). The ROC analysis revealed that the area under the curve(AUC) of spleen hardness at the 3^(rd) month after treatment was 0.644,while the AUCs of liver and spleen hardness at the 9^(th) month were 0.579 and 0.776,respectively. These might predict the prognosis of patients with portal hypertension.CONCLUSION Spleen hardness at the 3^(rd) month and liver and spleen shear wave velocity at the 9^(th) month may be used to assess the prognosis of patients with portal hypertension. This is hoped to be used as an indicator of predicting the prognosis of patients with portal hypertension.
基金National Natural Science Foundation of China(No.41874125,No.41430322).
文摘Accurate shear wave velocity is very important for seismic inversion.However,few researches in the shear wave velocity in organic shale have been carried out so far.In order to analyze the structure of organic shale and predict the shear wave velocity,the authors propose two methods based on petrophysical model and BP neural network respectively,to calculate shear wave velocity.For the method based on petrophysics model,the authors discuss the pore structure and the space taken by kerogen to construct a petrophysical model of the shale,and establish the quantitative relationship between the P-wave and S-wave velocities of shale and physical parameters such as pore aspect ratio,porosity and density.The best estimation of pore aspect ratio can be obtained by minimizing the error between the predictions and the actual measurements of the P-wave velocity.The optimal porosity aspect ratio and the shear wave velocity are predicted.For the BP neural network method that applying BP neural network to the shear wave prediction,the relationship between the physical properties of the shale and the elastic parameters is obtained by training the BP neural network,and the P-wave and S-wave velocities are predicted from the reservoir parameters based on the trained relationship.The above two methods were tested by using actual logging data of the shale reservoirs in the Jiaoshiba area of Sichuan Province.The predicted shear wave velocities of the two methods match well with the actual shear wave velocities,indicating that these two methods are effective in predicting shear wave velocity.
文摘A large number of Rayleigh wave dispersion curves recorded at twenty three seismic stations was used to investigate the 3-D shear wave velocity structure of the northeastern Brazilian lithosphere. A simple procedure to generate a three-dimensional image of Mohorovicic;discontinuity was applied in northeastern Brazil and the Moho 3-D image was in agreement with several isolated crustal thicknesses obtained with different geophysical methods. A detailed 3-D S wave velocity model is proposed for the region. In the crust, our model is more realist than CRUST2.0 global model, because it shows more details either laterally or in depth than global model, i.e., clear lateral variation and gradual increase of S wave velocity in depth. Down to 100 km depth, the 3-D S wave velocity model in northeastern Brazil is dominated by low velocities and this is consistent either with heat flow measurements or with measurements of the flexural strength of the lithosphere developed in the South American continent. Our 3-D S wave velocity model was also used to obtain the lithosphere thickness in each cell of the northeastern Brazil and the results were consistent with global studies about the Lithosphere-Asthenosphere Boundary worldwide.
文摘Shear wave velocity has numerous applications in geomechanical, petrophysical and geophysical studies of hydrocarbon reserves. However, data related to shear wave velocity isn’t available for all wells, especially old wells and it is very important to estimate this parameter using other well logging. Hence, lots of methods have been developed to estimate these data using other available information of reservoir. In this study, after processing and removing inappropriate petrophysical data, we estimated petrophysical properties affecting shear wave velocity of the reservoir and statistical methods were used to establish relationship between effective petrophysical properties and shear wave velocity. To predict (VS), first we used empirical relationships and then multivariate regression methods and neural networks were used. Multiple regression method is a powerful method that uses correlation between available information and desired parameter. Using this method, we can identify parameters affecting estimation of shear wave velocity. Neural networks can also be trained quickly and present a stable model for predicting shear wave velocity. For this reason, this method is known as “dynamic regression” compared with multiple regression. Neural network used in this study is not like a black box because we have used the results of multiple regression that can easily modify prediction of shear wave velocity through appropriate combination of data. The same information that was intended for multiple regression was used as input in neural networks, and shear wave velocity was obtained using compressional wave velocity and well logging data (neutron, density, gamma and deep resistivity) in carbonate rocks. The results show that methods applied in this carbonate reservoir was successful, so that shear wave velocity was predicted with about 92 and 95 percents of correlation coefficient in multiple regression and neural network method, respectively. Therefore, we propose using these methods to estimate shear wave velocity in wells without this parameter.
基金Pre-research Project of Yantai Unverity Under Project No. TM05B35Shandong Natural Science Foundation Under Project No. bs08003 Key Foundation of Ministry of Education Under Project No. 207062
文摘Soil shear wave velocity （SWV） is an important parameter in geotechnical engineering. To measure the soil SWV, three methods are generally used in China, including the single-hole method, cross-hole method and the surface-wave technique. An optimized approach based on a correlation function for single-hole SWV measurement is presented in this paper. In this approach, inherent inconsistencies of the artificial methods such as negative velocities, and too-large and too-small velocities, are eliminated from the single-hole method, and the efficiency of data processing is improved. In addition, verification using the cross-hole method of upper measuring points shows that the proposed optimized approach yields high precision in signal processing.
基金Supported by a grant from the National Natural Sciences Foundation of China(No.81571695)
文摘Objective The aim of this study was to evaluate the additional benefit of the difference of maximum and minimum shear wave velocity(SWV) values obtained at different probe orientations(D-value) for the differential diagnosis of breast tumors.Methods SWV(m/s) was measured in 123 breast tumors(92 benign,31 malignant) in 76 female patients with the probe placed on the transverse,longitudinal,and 45° planes.The areas under the receiver operating characteristic(AUROC) curves were compared with respect to the maximum SWV,minimum SWV,D-value,maximum SWV combined with the D-value,and minimum SWV combined with the D-value.Results There was a significant difference among the values of the maximum SWV,minimum SWV,and D-value for the 3 planes(P < 0.001).The AUROC curves for the maximum SWV,minimum SWV,and D-values of the 3 planes were 0.751(P = 0.379),0.486(P = 0.863),and 0.603(P = 0.204),respectively.The cutoff value for the maximum SWV for differentiating benign tumors from malignant tumors was 2.51 m/s(sensitivity 67%,specificity 50%).The cutoff value for the minimum SWV was 1.61 m/s(sensitivity 53%,specificity 50%).Adding the D-value increased the AUROC curve for the maximum SWV from 0.571 to 0.733 and the minimum SWV from 0.486 to 0.504(P = 0.964),respectively.Conclusion SWV differs in different planes of breast tumors.The D-value can provide a reference for the differential diagnosis of breast tumors.
基金Supported by Science and Technology Foundation of Pudong New District,No.PKJ2015-Y05)Medical and Industrial Interdisciplinary Fund of Shanghai Jiao Tong University,No.YG2016MS30+1 种基金General Program of Shanghai Health and Family Planning Commission,No.201740095Guiding Project of Shanghai Science and Technology Commission,No.19411965400
文摘BACKGROUND Several studies have demonstrated the feasibility and effectiveness of using ultrasound elastography to assess liver tissue stiffness.Virtual touch imaging quantification(VTIQ)based on acoustic radiation force impulse imaging has been developed as a latest and noninvasive method for assessing liver stiffness in children.AIM To determine the standard value in healthy children,and to identify possible factors that might influence the VTIQ measurement.METHODS With the ethical approval,202 children between 1 month and 15 years old were included in this study.None of them had any liver or systematic diseases.All children had a normal ultrasound scan and normal body mass index(BMI)range.The subjects were divided into four age and BMI groups.The effects of gender,age,liver lobe,measurement depth,and BMI on liver elasticity were investigated.RESULTS A significant correlation was found between age and shear wave velocity(SWV)value.At measurement depths of 1.5 cm and 2.0 cm in the left lobe,there were significant differences among the age groups.SWV values were significantly negatively correlated with the measurement depth.Gender,liver lobe,and BMI showed no significant effect on the SWV values.Age and BMI may influence the quality of the elastogram.CONCLUSION VTIQ is a noninvasive technique that is feasible to measure liver stiffness in children.The afore-mentioned velocity value obtained utilizing VTIQ method could be used as reference value for normal liver stiffness in children.
基金Project supported by the National Basic Research Program (973) of China (No. 2007CB714203)the China Postdoctoral Science Foun-dation (No. 20080430219)partly supported by the Foundation for Seismological Researches, China Earthquake Administration (No. 200808022)
文摘The bender element testing features its in-plane directivity, which allows using bender elements to measure the shear wave velocities in a wider range of in-plane configurations besides the standard tip-to-tip alignment. This paper proposed a novel bender element testing technique for measuring the horizontal shear wave velocity of soils, where the bender elements are surface- mounted and the axes of the source and receiver elements are parallel to each other. The preliminary tests performed on model ground of silica sand showed that, by properly determining the travel distance and time of the shear waves, the surface-mounted bender elements can perform as accurately as the conventional "tip-to-tip" configuration. Potentially, the present system provides a promising nondestructive tool for characterizing geomaterials and site conditions both in laboratory and in the fields.
基金grants from the Fundamental Research Funds for the Central Universities(No.2172015YGYL019)the Fundamental Research Funds for the Central Universities(No.2015LC021)+1 种基金National Natural Science Foundation of China(No.81000616)Hubei Key Laboratory of Molecular Imaging Research Funds(No.02.03.2015-149).
文摘The correlations between shear wave velocity(SWV)calculated from virtual touch tissue imaging quantification(VTIQ)technique and histological prognostic factors of invasive ductal carcinoma was investigated.A total of 76 breast tumors histologically confirmed as invasive ductal carcinomas were included in this study.SWV values were measured by VTIQ for each lesion preoperatively or prior to breast biopsy.The maximum values were recorded for statistical analysis.Medical records were reviewed to determine tumor size,histological grade,lymph node status and immunohistochemical results.Tumor subtypes were categorized as luminal A,luminal B,human epidermal growth factor receptor 2(HER2)positive and triple negative.The correlations between SWV and histological prognostic factors were analyzed.It was found that tumor size showed positive association with SWV(r=0.465,P<0.001).Larger tumors had significantly higher SWV than smaller ones(P=0.001).Histological grade 1 tumors had significantly lower SWV values than those with higher histological grade(P=0.015).The Ki67 expression,tumor subtypes and lymph node status showed no statistically significant correlations with SWV,although triple negative tumors and lymph node-positive tumors showed higher SWV values.It was concluded that tumor size was significantly associated with SWV.Higher histological grade was associated with increased SWV.There was no statistically significant correlations between SWV and other histological prognostic factors.
文摘This article presents a case study concerning a seismic characterization project.Full-wave sonic logging was used to characterize the shallow compressional wave and shear wave velocity profiles in the site.Anomalous values of the Poisson’s ratio derived from the velocity profiles suggested that the boreholes might have traversed slow formations(i.e.with shear wave velocity smaller than the borehole fluid compressional wave velocity or“mud-wave speed”)and that conventional processing of the sonic logs might have misinterpreted the direct arrivals of fluid acoustic waves as arrivals caused by shear wave propagation in the rock.Consequently,the shear wave velocity profiles provided by the contractor were considered to be unreliable by the project team.To address these problems,a non-conventional determination of the shear wave velocity was implemented,based on the relationship between the Poisson’s ratio of the rock formation and the shape of the first train of sonic waves which arrived to the receivers in the sonic probe.The relationship was determined based on several hundreds of finite element simulations of the acoustic wave propagation in boreholes with the same diameter as used in the perforations.The present article describes how this non-conventional approach was developed and implemented to obtain the shear wave velocity profiles from the raw sonic logs.The approach allows an extension of the range of applicability of full-wave sonic logging to determination of shear wave velocity profiles in formations with low compressional wave velocities.The method could be used to obtain shear wave velocity profiles where compressional wave velocity is as low as slightly larger than the mud-wave speed.A sample sonic log in Log ASCII Standard(LAS)format is provided as supplementary material to this paper via Mendeley Data,together with the FORTRAN source code used to process the log following the approach described in this study.
文摘The main purpose of current study is development of an intelligent model for estimation of shear wave velocity in limestone. Shear wave velocity is one of the most important rock dynamic parameters. Because rocks have complicated structure, direct determination of this parameter takes time, spends expenditure and requires accuracy. On the other hand, there are no precise equations for indirect determination of it; most of them are empirical. By using data sets of several dams of Iran and neuro-genetic, adaptive neuro-fuzzy inference system （ANFIS）, and gene expression programming （GEP） methods, models are rendered for prediction of shear wave velocity in limestone. Totally, 516 sets of data has been used for modeling. From these data sets, 413 ones have been utilized for building the intelligent model, and 103 have been used for their performance evaluation. Compressional wave velocity （Vp）, density （7） and porosity （.n）, were considered as input parameters. Respectively, the amount of R for neuro-genetic and ANFIS networks was 0.959 and 0.963. In addition, by using GEP, three equations are obtained; the best of them has 0.958R. ANFIS shows the best prediction results, whereas GEP indicates proper equations. Because these equations have accuracy, they could be used for prediction of shear wave velocity for limestone in the future.
文摘Objective: To study the differential value of shear wave velocity (SWV) in nodules quantitatively determined by acoustic radiation force impulse (ARFI) for benign and malignant thyroid nodules. Methods: Patients who were diagnosed with thyroid nodules in the People's Hospital of Hai'an County between June 2014 and February 2017 were selected and divided into those with benign thyroid nodules and malignant thyroid nodules according to the biopsy results. Before biopsy, the ARFI ultrasonic elastography was performed to measure SWV, and the biopsy tissue was collected after biopsy to determine the expression of proliferation molecules and invasion molecules. Results: The SWV of malignant thyroid nodules was significantly higher than that of benign thyroid nodules;P53, CyclinG2, E-cadherin, TIMP1 and TIMP3 mRNA expression in malignant thyroid nodules were significantly lower than those in benign thyroid nodules while FOXA1, Survivin, XIAP, Twist and Vimentin mRNA expression were significantly higher than those in benign thyroid nodules;P53, CyclinG2, E-cadherin, TIMP1 and TIMP3 mRNA expression in malignant thyroid nodules with high SWV were significantly lower than those in malignant thyroid nodules with low SWV while FOXA1, Survivin, XIAP, Twist and Vimentin mRNA expression were significantly higher than those in malignant thyroid nodules with low SWV. Conclusion: The SWV of malignant thyroid nodules significantly increases and is closely related to the abnormal proliferation and invasion of cancer cells.
基金Natural Science Foundation of China No:81170108.
文摘Objective:To discuss the relationship of ultrasonic shear wave velocity (SWV) with oncogene and tumor suppressor gene expression in primary liver cancer lesions as well as angiogenesis factor contents.Methods:100 patients with primary liver cancer who underwent surgical treatment in our hospital between March 2014 and September 2016 were collected as observation group, and 50 healthy subjects who received physical examination in our hospital during the same period were collected as normal control group. The ultrasonic SWV levels of two groups of subjects were measured before the operation, and the observation groups were further divided into high SWV group and low SWV group, 50 cases in each group. Intraoperative tumor tissue samples were kept and fluorescence quantitative PCR was used to determine the mRNA expression of oncogenes and tumor suppressor genes. Enzyme-linked immunosorbent assay was used to determine serum contents of angiogenesis factors in observation group before operation.Results:Hepatic ultrasonic SWV level in observation group was significantly higher than that in normal control group;proto-oncogene CK, Ki67, Gly-3, Survivin and Pokemon mRNA expression in tumor tissue of high SWV group were higher than those of low SWV group while tumor suppressor genes Tg737, p16, p27, PTEN and runx3 mRNA expression were lower than those of low SWV group;serum angiogenesis factors VEGF, MMP-9 and IGF-1R contents were higher than those in low SWV group. Conclusion: The hepatic ultrasonic SWV level increases in patients with primary liver cancer, and the SWV level is directly correlated with oncogene and tumor suppressor gene expression as well as angiogenesis factor contents.
文摘Shear wave elastography(SWE)is now becoming an indispensable diagnostic tool in the routine examination of liver diseases.In particular,accuracy is required for shear wave propagation velocity measurement,which is directly related to diagnostic accuracy.It is generally accepted that the liver shear wave propagation velocity reflects the degree of fibrosis,but there are still few reports on other factors that increase the shear wave propagation velocity.In this study,we reviewed such factors in the literature and examined their mechanisms.Current SWE measures propagation velocity based on the assumption that the medium has a homogeneous structure,uniform density,and is purely elastic.Otherwise,the measurement is subject to error.The other(confounding)factors that we routinely experience are primarily:(1)Conditions that appear to increase the viscous component;and(2)Conditions that appear to increase tissue density.Clinically,the former includes acute hepatitis,congested liver,biliary obstruction,etc,and the latter includes diffuse infiltration of malignant cells,various storage diseases,tissue necrosis,etc.In any case,it is important to evaluate SWE in the context of the entire clinical picture.
基金Project supported by the National Natural Science Foundation of China (No. 10372089), and Department of Education of Zhejiang Province (No. 20010572), China
文摘Recent studies using field case history data yielded new criteria for evaluating liquefaction potential in saturated granular deposits based on in situ, stress-corrected shear wave velocity. However, the conditions of relatively insufficient case histories and limited site conditions in this approach call for additional data to more reliably define liquefaction resistance as a function of shear wave velocity. In this study, a series of undrained cyclic triaxial tests were conducted on saturated sand with shear wave velocity Vs measured by bender element. By normalizing the data with respect to minimum void ratio, the test results, in-corporated with previously published laboratory data, statistically revealed good correlation of cyclic shear strength with small-strain shear modulus for sandy soils, which is almost irrespective of soil types and confining pressures. The consequently determined cyclic resistance ratio, CRR, was found to be approximately proportional to Vs4. Liquefaction resistance boundary curves were established by applying this relationship and compared to liquefaction criteria derived from seismic field measure-ments. Although in the range of Vs1>200 m/s the presented curves are moderately conservative, they are remarkably consistent with the published field performance criteria on the whole.
基金supported by the open fund from the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resource,Institute of Geology,Chinese Academy of Geological Sciences(J1901-16)by the fund from the State Key Laboratory of Geodesy and Earth’s Dynamics,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences(S21L6403)。
文摘The crustal structure in Myanmar can provide valuable information for the eastern margin of the ongoing IndoEurasian collision system.We successively performed H-k stacking of the receiver function and joint inversion of the receiver function and surface wave dispersion to invert the crustal thickness(H),shear wave velocity(V_(S)),and the V_(P)/V_(S) ratio(k)beneath nine permanent seismic stations in Myanmar.H was found to increase from 26 km in the south and east of the study area to 51 km in the north and west,and the V_(P)/V_(S) ratio was complex and high.Striking differences in the crust were observed for different tectonic areas.In the Indo-Burma Range,the thick crust(H~51 km)and lower velocities may be related to the accretionary wedge from the Indian Plate.In the Central Myanmar Basin,the thin crust(H=26.9-35.5 km)and complex V_(P)/V_(S) ratio and V_(S) suggest extensional tectonics.In the Eastern Shan Plateau,the relatively thick crust and normal V_(P)/V_(S) ratio are consistent with its location along the western edge of the rigid Sunda Block.
文摘This research aims at improving the methods of prediction of shear wave velocity in underground layers. We propose and showcase our methodology using a case study on the Mashhad plain in north eastern part of Iran. Geotechnical investigations had previously reported nine measurements of the SASW (Spectral Analysis of Surface Waves) method over this field and above wells which have DHT (Down Hole Test) result. Since SASW utilizes an analytical formula (which suffers from some simplicities and noise) for evaluating shear wave velocity, we use the results of SASW in a trained artificial neural network (ANN) to estimate the un- known nonlinear relationships between SASW results and those obtained by the method of DHT (treated here as real values). Our results show that an appropriately trained neural network can reliably predict the shear wave velocity between wells accurately.
文摘Shear wave velocity Vs is measured by the surface geophysical survey like MASW （multi-channel surface wave analysis） or RWM （refraction wave method） and by the subsurface method like PS logging. PS logging and RWM are direct methods to derive shear wave velocity and MASW retrieves shear wave through the inversion of the surface wave. In this work, the effectiveness of surface methods （MASW and RWM） is compared with PS logging in determining shear wave velocity. For this purpose, shear wave velocity results Vs30 of 12 PS logging and MASW surveys conducted in Mymensingh Municipality in Bangladesh have been utilized. Additionally, the shear wave velocity results of three PS logging have been compared with the refraction profiles of RWM survey conducted in Rooppur nuclear power plant site in Bangladesh. The relative discrepancy between RWM and PS logging is found less （ranges from -3.92 to 0.93） compared to MASW and PS logging （＋/-0.88 to 33.92）. The correlation coefficient of Vs30 derived from RWM and PS logging is observed much better （0.60） compared to MASW and PS logging （0.40）. The result is good considering the lateral lithologic variability and inherent differences among techniques. It is evident from the comparison that the RWM can be used as a cost-effective alternative to traditional borehole PS logging method for Vs30 determination and thus the number of down-hole logging tests might be significantly reduced.
