期刊文献+
共找到3,737篇文章
< 1 2 187 >
每页显示 20 50 100
Assessment of liquefaction potential based on shear wave velocity:Strain energy approach
1
作者 Mohammad Hassan Baziar Mahdi Alibolandi 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第9期3733-3745,共13页
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
关键词 LIQUEFACTION Strain energy capacity shear wave velocity Cyclic triaxial test Cyclic direct simple shear test Resonant column test Bender element test
下载PDF
Predicting hepatocellular carcinoma: A new non-invasive model based on shear wave elastography
2
作者 Dong Jiang Yi Qian +9 位作者 Yi-Jun Gu Ru Wang Hua Yu Hui Dong Dong-Yu Chen Yan Chen Hao-Zheng Jiang Bi-Bo Tan Min Peng Yi-Ran Li 《World Journal of Gastroenterology》 SCIE CAS 2024年第25期3166-3178,共13页
BACKGROUND Integrating conventional ultrasound features with 2D shear wave elastography(2D-SWE)can potentially enhance preoperative hepatocellular carcinoma(HCC)predictions.AIM To develop a 2D-SWE-based predictive mod... BACKGROUND Integrating conventional ultrasound features with 2D shear wave elastography(2D-SWE)can potentially enhance preoperative hepatocellular carcinoma(HCC)predictions.AIM To develop a 2D-SWE-based predictive model for preoperative identification of HCC.METHODS A retrospective analysis of 884 patients who underwent liver resection and pathology evaluation from February 2021 to August 2023 was conducted at the Oriental Hepatobiliary Surgery Hospital.The patients were divided into the modeling group(n=720)and the control group(n=164).The study included conventional ultrasound,2D-SWE,and preoperative laboratory tests.Multiple logistic regression was used to identify independent predictive factors for RESULTS In the modeling group analysis,maximal elasticity(Emax)of tumors and their peripheries,platelet count,cirrhosis,and blood flow were independent risk indicators for malignancies.These factors yielded an area under the curve of 0.77(95%confidence interval:0.73-0.81)with 84%sensitivity and 61%specificity.The model demonstrated good calibration in both the construction and validation cohorts,as shown by the calibration graph and Hosmer-Lemeshow test(P=0.683 and P=0.658,respectively).Additionally,the mean elasticity(Emean)of the tumor periphery was identified as a risk factor for microvascular invasion(MVI)in malignant liver tumors(P=0.003).Patients receiving antiviral treatment differed significantly in platelet count(P=0.002),Emax of tumors(P=0.033),Emean of tumors(P=0.042),Emax at tumor periphery(P<0.001),and Emean at tumor periphery(P=0.003).CONCLUSION 2D-SWE’s hardness value serves as a valuable marker for enhancing the preoperative diagnosis of malignant liver lesions,correlating significantly with MVI and antiviral treatment efficacy. 展开更多
关键词 shear wave elastography Predicting model Microvascular invasion Antiviral treatment Hepatocellular carcinoma
下载PDF
Shear wave velocity model using HVSR inversion beneath Bandar Lampung City
3
作者 Ahmad Zaenudin Alhada Farduwin +1 位作者 Gede I Boy Darmawan Karyanto 《Earthquake Science》 2024年第4期337-351,共15页
The horizontal-to-vertical spectral ratio(HVSR)method has been used to characterize site-effect parameters that are indispensable in seismic hazard and risk-reduction studies in urban areas and rapid land-use planning... The horizontal-to-vertical spectral ratio(HVSR)method has been used to characterize site-effect parameters that are indispensable in seismic hazard and risk-reduction studies in urban areas and rapid land-use planning.This method is widely used because it is the cheapest and simplest geophysical method for the acquisition and processing stages.In subsequent developments,the HVSR method has been widely used to determine elastic rock parameters,particularly shear wave velocity(v_(S)),through the HVSR curve inversion process.Furthermore,the v_(S)structural model can be used to delineate the presence of complex geological structures,particularly faults and sedimentary basins.Bandar Lampung is a city in Lampung Province with many fault structures and groundwater basins to the south.There are 83 HVSR measurement points around Bandar Lampung for delineating the presence of fault structures and groundwater basins.We produced the HVSR curve from the measurement results and then performed an inversion process using the particle swarm optimization algorithm to obtain v_(S)for the depth profile.Subsequently,from this profile,we produced a two-dimensional(2D)lateral and vertical model.The mean v_(S)value was calculated from all the measurement points,and we found stiff soil layers reaching depths of approximately 5 m,with a value of v_(S)<330 m/s.A bedrock layer with a velocity exceeding 1250 m/s was visible at a depth of 100 m.Based on the 2D model,the v_(S)structure shows that the city of Bandar Lampung is divided into two zones,with a NW-SE boundary.The north-middle-eastern part of the city consists of harder rocks.This harder rock is characterized by extremely high v_(S)values,starting from a depth of 50 m.In contrast,the south-middle-west exhibits a low-moderate v_(S)anomaly associated with groundwater basins SW of the city.From the 2D v_(S)structural model,fault structures can be found along the city,characterized by a contrast of v_(S)values from low to medium and from medium to high. 展开更多
关键词 shear wave velocity HVSR fault structures groundwater basin Bandar Lampung City
下载PDF
Seismic anisotropy and upper mantle dynamics in Alaska:A review of shear wave splitting analyses
4
作者 Zhaofeng Jin Yuchen Yang +7 位作者 Muhammad Ishaidir Siregar Zihao Mu S.M.Ariful Islam Qichao Zhao Dan Wang Fan Zhang Xugang Yang Liwei Song 《Earthquake Research Advances》 CSCD 2024年第2期72-81,共10页
Shear wave splitting(SWS)is regarded as the most effective geophysical method to delineate mantle flow fields by detecting seismic azimuthal anisotropy in the earth's upper mantle,especially in tectonically active... Shear wave splitting(SWS)is regarded as the most effective geophysical method to delineate mantle flow fields by detecting seismic azimuthal anisotropy in the earth's upper mantle,especially in tectonically active regions such as subduction zones.The Aleutian-Alaska subduction zone has a convergence rate of approximately 50 mm/yr,with a trench length reaching nearly 2800 km.Such a long subduction zone has led to intensive continental deformation and numerous strong earthquakes in southern and central Alaska,while northern Alaska is relatively inactive.The sharp contrast makes Alaska a favorable locale to investigate the impact of subduction on mantle dynamics.Moreover,the uniqueness of this subduction zone,including the unusual subducting type,varying slab geometry,and atypical magmatic activity and composition,has intrigued the curiosity of many geoscientists.To identify different sources of seismic anisotropy beneath the Alaska region and probe the influence of a geometrically varying subducting slab on mantle dynamics,extensive SWS analyses have been conducted in the past decades.However,the insufficient station and azimuthal coverage,especially in early studies,not only led to some conflicting results but also strongly limited the in-depth investigation of layered anisotropy and the estimation of anisotropy depth.With the completion of the Transportable Array project in Alaska,recent studies have revealed more detailed mantle structures and characteristics based on the dense station coverage and newly collected massive seismic data.In this study,we review significant regional-and continental-scale SWS studies in the Alaska region and conclude the mantle flow fields therein,to understand how a geometrically varying subducting slab alters the regional mantle dynamics.The summarized mantle flow mechanisms are believed to be conducive to the understanding of seismic anisotropy patterns in other subduction zones with a complicated tectonic setting. 展开更多
关键词 Seismic anisotropy shear wave splitting Mantle flow Alaska subduction zone SLAB
下载PDF
Application of real-time shear wave elastography to Achilles tendon hardness evaluation in older adults
5
作者 Xuan He Xin Wei +2 位作者 Jia Hou Wei Tan Ping Luo 《World Journal of Clinical Cases》 SCIE 2024年第26期5922-5929,共8页
BACKGROUND Real-time shear wave elastography(SWE)is a non-invasive imaging technique used to measure tissue stiffness by generating and tracking shear waves in real time.This advanced ultrasound-based method provides ... BACKGROUND Real-time shear wave elastography(SWE)is a non-invasive imaging technique used to measure tissue stiffness by generating and tracking shear waves in real time.This advanced ultrasound-based method provides quantitative information regarding tissue elasticity,offering valuable insights into the mechanical properties of biological tissues.However,the application of real-time SWE in the musculoskeletal system and sports medicine has not been extensively studied.AIM To explore the practical value of real-time SWE for assessing Achilles tendon hardness in older adults.METHODS A total of 60 participants were enrolled in the present study,and differences in the elastic moduli of the bilateral Achilles tendons were compared among the following categories:(1)Age:55-60,60-65,and 65-70-years-old;(2)Sex:Male and female;(3)Laterality:Left and right sides;(4)Tendon state:Relaxed and tense state;and(5)Tendon segment:Proximal,middle,and distal.RESULTS There were no significant differences in the elastic moduli of the bilateral Achilles tendons when comparing by age or sex(P>0.05).There were,however,significant differences when comparing by tendon side,state,or segment(P<0.05).CONCLUSION Real-time SWE plays a significant role compared to other examination methods in the evaluation of Achilles tendon hardness in older adults. 展开更多
关键词 Aged Achilles tendon REAL-TIME shear wave elastography Young’s modulus Muscle stiffness
下载PDF
Does shear wave elastography technology provide better value for the assessment of perianal fistulizing Crohn’s disease?
6
作者 Jiong Wu 《World Journal of Gastrointestinal Surgery》 SCIE 2024年第11期3636-3638,共3页
Magnetic resonance imaging is the gold standard compared other clinical fin-dings.But shear wave elastography technique combined with endoscopic ultra-sound can evaluate the degree of fibrosis of fistula tissue in Cr... Magnetic resonance imaging is the gold standard compared other clinical fin-dings.But shear wave elastography technique combined with endoscopic ultra-sound can evaluate the degree of fibrosis of fistula tissue in Crohn’s disease patients.This topic is highly relevant to the current discourse,especially for It shows a certain degree of innovation and practicality and is worthy of study and popularization. 展开更多
关键词 Perianal fistulizing Crohn’s disease shear wave elastography ULTRASOUND Magnetic resonance imaging
下载PDF
Shear wave splitting analysis of local earthquakes from dense arrays in Shimian,Sichuan 被引量:2
7
作者 Sha Liu Baofeng Tian 《Earthquake Science》 2023年第1期52-63,共12页
The Shimian area of Sichuan sits at the junction of the Bayan Har block.Sichuan-Yunnan rhombic block,and Yangtze block,where several faults intersect.This region features intense tectonic activity and frequent earthqu... The Shimian area of Sichuan sits at the junction of the Bayan Har block.Sichuan-Yunnan rhombic block,and Yangtze block,where several faults intersect.This region features intense tectonic activity and frequent earthquakes.In this study,we used local seismic waveform data recorded using dense arrays deployed in the Shimian area to obtain the shear wave splitting parameters at 55 seismic stations and thereby determine the crustal anisotropic characteristics of the region.We then analyzed the crustal stress pattern and tectonic setting and explored their relationship in the study area.Although some stations returned a polarization direction of NNW-SSE.a dominant polarization direction of NW-SE was obtained for the fast shear wave at most seismic stations in the study area.The polarization directions of the fast shear wave were highly consistent throughout the study-area.This orientation was in accordance with the direction of the regional principal compressive stress and parallel to the trend of the Xianshuihe and Daliangshan faults.The distribution of crustal anisotropy in this area was affected by the regional tectonic stress field and the fault structures.The mean delay time between fast and slow shear waves was 3.83 ms/km.slightly greater than the values obtained in other regions of Sichuan.This indicates that the crustal media in our study area had a high anisotropic strength and also reveals the influence of tectonic complexity resulting from the intersection of multiple faults on the strength of seismic anisotropy. 展开更多
关键词 shear wave splitting polarization direction of the fast shear wave regional principal compressive stress dense array Citation:Liu S and Tian BF(2023).shear wave splitting analysis of local earthquakes from dense arrays in Shimian Sichuan.
下载PDF
Combining the age-male-albumin-bilirubin-platelets score and shear wave elastography stratifies carcinogenic risk in hepatitis C patients after viral clearance 被引量:1
8
作者 Rion Masaoka Yoshinori Gyotoku +2 位作者 Ryosaku Shirahashi Toshikuni Suda Masaya Tamano 《World Journal of Clinical Cases》 SCIE 2023年第22期5204-5214,共11页
BACKGROUND The treatment of hepatitis C with direct-acting antiviral agents(DAAs)produces a high rate of sustained virological response(SVR)with fewer adverse events than interferon(IFN)therapy with a similar effect i... BACKGROUND The treatment of hepatitis C with direct-acting antiviral agents(DAAs)produces a high rate of sustained virological response(SVR)with fewer adverse events than interferon(IFN)therapy with a similar effect in inhibiting carcinogenesis as IFN therapy.The age-male-albumin-bilirubin-platelets(aMAP)score is useful for stratifying the risk of hepatocellular carcinoma in chronic hepatitis patients,and the velocity of shear waves(Vs)measured by shear wave elastography has also been shown to be useful for diagnosing the level of fibrotic progression in hepatitis C and predicting carcinogenic risk.Combining these two may improve the prediction of carcinogenic risk.AIM To determine whether combining the aMAP score with Vs improves carcinogenic risk stratification in medium-to-high-risk hepatitis C patients.METHODS This retrospective,observational study involved hepatitis C patients treated with DAAs who achieved SVR.Vs was measured before treatment(baseline),at the end of treatment(EOT),and 12 wk(follow-up 12)and 24 wk(follow-up 24)after treatment.The patients were followed for at least six months after EOT to determine whether cancer developed.Multiple regression analysis was used to identify factors contributing to hepatic carcinogenesis.The diagnostic performances of clinical parameters for predicting the presence of hepatocellular carcinoma were evaluated using receiver-operating characteristic(ROC)curve analyses.RESULTS A total of 279 patients(mean age 65.9 years,118 males,161 females)were included in the analysis.Multiple regression analysis was performed with carcinogenesis as the target variable and alanine aminotransferase,platelets,α-fetoprotein,Vs,and the Fib-4 index as explanatory variables;only Vs was found to be significant(P=0.0296).The cut-off value for Vs for liver carcinogenesis calculated using the ROC curve was 1.53 m/s.Carcinoma developed in 2.0%(3/151)of those with Vs<1.53 m/s and in 10.5%(9/86)of those with Vs≥1.53 m/s.CONCLUSION In hepatitis C patients after SVR,combining the aMAP score and Vs to stratify the risk of carcinogenesis is more efficient than uniform surveillance of all patients. 展开更多
关键词 Hepatitis C Hepatocellular carcinoma Direct-acting antiviral therapy shear wave elastography Sustained virological response Age-male-albumin-bilirubin-platelets score
下载PDF
Comparative analysis of conventional ultrasound and shear wave elastography features in primary breast diffuse large B-cell lymphoma
9
作者 Xiao-Duan Zhang Kai Zhang 《World Journal of Clinical Cases》 SCIE 2023年第33期7994-8002,共9页
BACKGROUND Primary breast diffuse large B-cell lymphoma(PB-DLBCL)is a rare subtype of non-Hodgkin lymphoma that accounts for<3%of extranodal lymphomas and 1%of breast tumors.Its diagnosis and management are challen... BACKGROUND Primary breast diffuse large B-cell lymphoma(PB-DLBCL)is a rare subtype of non-Hodgkin lymphoma that accounts for<3%of extranodal lymphomas and 1%of breast tumors.Its diagnosis and management are challenging because of its rarity,heterogeneity,and aggressive behavior.Conventional ultrasound(US)is the first-line imaging modality for breast lesions;however,it has limited specificity and accuracy for PB-DLBCL.Shear wave elastography(SWE)is a novel US technique that measures tissue stiffness and may reflect the histological characteristics and biological behavior of breast lesions.AIM To compare the conventional US and SWE features of PB-DLBCL and evaluate their diagnostic performance and prognostic value.METHODS We retrospectively reviewed the clinical data and US images of 32 patients with pathologically confirmed PB-DLBCL who underwent conventional US and SWE before treatment.We analyzed conventional US features(shape,margin,orientation,echo,posterior acoustic features,calcification,and vascularity)and SWE features(mean elasticity value,standard deviation,minimum elasticity value,maximum elasticity value,and lesion-to-fat ratio)of the PB-DLBCL lesions.Using receiver operating characteristic curve analysis,we determined the optimal cutoff values and diagnostic performance of conventional US and SWE features.We also performed a survival analysis to assess the prognostic value of conventional US and SWE features.RESULTS The results showed that the PB-DLBCL lesions were mostly irregular in shape(84.4%),microlobulated or spiculated in margins(75%),parallel in orientation(65.6%),hypoechoic in echo(87.5%),and had posterior acoustic enhancement(65.6%).Calcification was rare(6.3%)and vascularity was variable(31.3%avascular,37.5%hypovascular,and 31.3%hypervascular).The mean elasticity value of PB-DLBCL lesions was significantly higher than that of benign breast lesions(113.4±46.9 kPa vs 27.8±16.4 kPa,P<0.001).The optimal cutoff value of the mean elasticity for distinguishing PB-DLBCL from benign breast lesions was 54.5 kPa,with a sensitivity of 93.8%,specificity of 92.9%,positive predictive value of 93.8%,negative predictive value of 92.9%,and accuracy of 93.3%.The mean elasticity value was also significantly correlated with Ki-67 expression level(r=0.612,P<0.001),which is a marker of tumor proliferation and aggressiveness.Survival analysis showed that patients with higher mean elasticity values(>54.5 kPa)had worse overall survival(OS)and progression-free survival(PFS)than those with lower mean elasticity values(<54.5 kPa)(P=0.038 for OS and P=0.027 for PFS).CONCLUSION Conventional US and SWE provide useful information for diagnosing and forecasting PB-DLBCL.SWE excels in distinguishing PB-DLBCL from benign breast lesions,reflects tumor proliferation and aggressiveness,and improves disease management. 展开更多
关键词 Primary breast diffuse large B-cell lymphoma Conventional ultrasound shear wave elastography Diagnosis PROGNOSIS Tumor behavior
下载PDF
Optimization design of conical reaction teeth of shear wave vibroseis vibration plate
10
作者 WANG Hongxiang DU Lizhi SUN Zhen 《Global Geology》 2023年第4期264-272,共9页
The vibrator plate is the link between the vibroseis vehicle and the earth,as well as the core com-ponent of the vibrator vehicle.In this paper,the coupling effect between the vibrator plate and the earth is an-alyzed... The vibrator plate is the link between the vibroseis vehicle and the earth,as well as the core com-ponent of the vibrator vehicle.In this paper,the coupling effect between the vibrator plate and the earth is an-alyzed from two aspects of reaction tooth arrangement and reaction tooth conical angle,and three groups of experimental models are optimized and designed.The model construction and numerical analysis of the shear wave vibroseis vibrator plate are carried out with ANSYS software.The motion law between the vibration plate and the earth at work was studied,the strain energy of the three experimental models in operation,the maximum displacement of particle at the same position and other reference indices were compared and ana-lyzed,with 28 conical reaction teeth were arranged on both sides.The coupling effect between the vibration plate and the earth was best when the tooth angle was 60°.Compared with the toothless vibration plate,the energy efficiency is improved by about 20%,and the coupling effect between the vibrator plate and the earth is effectively enhanced.It is found that the coupling effect is enhanced through increasing the number of reac-tion teeth of the vibration plate by increasing the coupling area between the vibration plate and the earth. 展开更多
关键词 shear wave vibroseis vibration plate conical reaction teeth
下载PDF
Real-time Shear Wave Elastography Assessment of Muscle Elasticity in Patients with Renal Failure
11
作者 Lei Ran Lei Wang Tingting Cai 《Journal of Clinical and Nursing Research》 2023年第5期66-71,共6页
Objective:To explore the value of real-time elastic shear wave in evaluating muscle elasticity in patients with renal failure.Methods:50 patients with chronic renal failure from January 2019 to December 2022 were rand... Objective:To explore the value of real-time elastic shear wave in evaluating muscle elasticity in patients with renal failure.Methods:50 patients with chronic renal failure from January 2019 to December 2022 were randomly selected as the experimental group,and 50 healthy patients aged 21-61 during the same period were selected as the control group,and the basic information of the patients,including age,gender,body mass index,etc.,were collected.Besides,the Young's modulus of the two groups of patients were observed and analyzed.Results:The Young's modulus values of left and right gastrocnemius muscles in the experimental group were significantly lower than those in the control group(P<0.05),and there was no statistical difference between the left and right sides of the experimental group and the control group(P>0.05).Conclusion:Real-time shear wave elastography provides a non-invasive,real-time and effective tool for the assessment of muscle elasticity in patients with renal failure.Through further research and optimization,real-time shear wave elastography will play a greater role in the prevention and treatment of patients with renal failure,improving the quality of life and prognosis of patients. 展开更多
关键词 Real-time shear wave elastography Renal failure Muscle elasticity
下载PDF
Assessment of Calf Skeletal Muscle Stiffness in Diabetic Nephropathy Patients with Medial Tibial Stress Syndrome by Two-Dimensional Shear Wave Elastography
12
作者 Lei Wang Lei Ran 《Proceedings of Anticancer Research》 2023年第5期11-16,共6页
Objective:To explore the feasibility of two-dimensional shear wave elastography in evaluating calf skeletal muscle stiffness in diabetic nephropathy patients with medial tibial stress syndrome.Methods:A total of 48 di... Objective:To explore the feasibility of two-dimensional shear wave elastography in evaluating calf skeletal muscle stiffness in diabetic nephropathy patients with medial tibial stress syndrome.Methods:A total of 48 diabetic nephropathy patients with medial tibial stress syndrome from January 2020 to December 2022 were included as the study group,and 48 patients with diabetic nephropathy during the same period were included as the control group.Both groups were detected by two-dimensional shear wave elastography with ultrasonic equipment,and Young‘s modulus of the tibialis anterior muscle,tibialis posterior muscle,and gastrocnemius muscle were observed and analyzed in the two groups.Results:The Young‘s modulus values of tibialis anterior muscle,tibialis posterior muscle,and gastrocnemius muscle in the study group were significantly lower than those in the control group(P<0.05).Conclusion:Two-dimensional shear wave elastography is feasible for the evaluation of calf skeletal muscle stiffness in diabetic nephropathy patients with medial tibial stress syndrome,and has high accuracy and repeatability.This technique can be used to diagnose,treat and monitor muscle lesions in patients with diabetic nephropathy,and can also be used to assess muscle fatigue and exercise capacity,which has broad application prospects. 展开更多
关键词 Two-dimensional shear wave elastography Diabetic nephropathy Medial tibial stress syndrome
下载PDF
The characteristics of shear wave splitting in the source region of the April 20,2013 Lushan earthquake 被引量:2
13
作者 Sha Liu Jiansi Yang +3 位作者 Baofeng Tian Yu Zheng Xudong Jiang Zhiqiang Xu 《Earthquake Science》 2013年第3期223-228,共6页
Using seismic data of the aftershocks sequence of the April 20, 2013 Lushan earthquake recorded by seismic temporary and permanent stations in the source region, with the visual inspection of particle motion diagrams,... Using seismic data of the aftershocks sequence of the April 20, 2013 Lushan earthquake recorded by seismic temporary and permanent stations in the source region, with the visual inspection of particle motion diagrams, this paper preliminarily contains the polarization directions of fast shear wave and the time-delays of split shear waves at every station, and analyzes the crustal anisotropic characteristics in the source region. In the study area, the polarization direc- tions at stations BAX, TQU, L 132, L 133, L 134, and L 135 are northeast, which is consistent with the strike of Dachuan- Shuangshi fault. There are two polarization directions at MDS and L131, which are northeast and southeast. The scatter of polarization directions suggests the complex stress field around these two stations where two faults intersect. For the normalized time-delays at every station, the range is 1.02-8.64 ms/km. The largest time-delay is from L134 which is closest to the mainshock, and the smallest one is from L133. The variations in time-delays show the decreasing at stations BAX, L134, and L135 because of the stress-relaxation after earthquake. 展开更多
关键词 Lushan earthquake shear wavesplitting Polarization direction of fast shear wave Time-delay of split shear wave
下载PDF
Shear wave velocity prediction during CO_2-EOR and sequestration in the Gao89 well block of the Shengli Oilfield 被引量:2
14
作者 李琳 马劲风 +4 位作者 王浩璠 谭明友 崔世凌 张云银 曲志鹏 《Applied Geophysics》 SCIE CSCD 2017年第3期372-380,460,共10页
Shear-wave velocity is a key parameter for calibrating monitoring time-lapse 4D seismic data during CO2-EOR (Enhanced Oil Recovery) and CO2 sequestration. However, actual S-wave velocity data are lacking, especially... Shear-wave velocity is a key parameter for calibrating monitoring time-lapse 4D seismic data during CO2-EOR (Enhanced Oil Recovery) and CO2 sequestration. However, actual S-wave velocity data are lacking, especially in 4D data for CO2 sequestration because wells are closed after the CO2 injection and seismic monitoring is continued but no well log data are acquired. When CO2 is injected into a reservoir, the pressure and saturation of the reservoirs change as well as the elastic parameters of the reservoir rocks. We propose a method to predict the S-wave velocity in reservoirs at different pressures and porosities based on the Hertz-Mindlin and Gassmann equations. Because the coordination number is unknown in the Hertz Mindlin equation, we propose a new method to predict it. Thus, we use data at different CO2 injection stages in the Gao89 well block, Shengli Oilfield. First, the sand and mud beds are separated based on the structural characteristics of the thin sand beds and then the S-wave velocity as a function of reservoir pressure and porosity is calculated. Finally, synthetic seismic seismograms are generated based on the predicted P- and S-wave velocities at different stages of CO2 injection. 展开更多
关键词 coordination number bulk modulus shear modulus Hertz-Mindlin shear wave CO2-EOR
下载PDF
Shear Wave Elastography of Invasive Ductal Carcinoma:Correlations between Shear Wave Velocity and Histological Prognostic Factors 被引量:1
15
作者 Xiao-qing HU Li PENG +3 位作者 Max Wintermark Jafi Alyssa Lipson Yan-rong ZHANG Yuan GAO 《Current Medical Science》 SCIE CAS 2021年第1期173-179,共7页
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
关键词 shear wave elastography virtual touch tissue imaging quantification shear wave velocity invasive ductal carcinoma histological prognostic factors
下载PDF
Three dimensional shear wave velocity structure of crust and upper mantle in South China Sea and its adjacent regions by surface waveform inversion 被引量:22
16
作者 曹小林 朱介寿 +2 位作者 赵连锋 曹家敏 洪学海 《地震学报》 CSCD 北大核心 2001年第2期113-124,共12页
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
关键词 面波波形 分块波形反演 三维S波速度结构 中国数字地震台网 “检验板”法 岩石圈
下载PDF
Shear wave velocity is a useful marker for managing nonalcoholic steatohepatitis 被引量:31
17
作者 Akihiko Osaki Tomoyuki Kubota +11 位作者 Takeshi Suda Masato Igarashi Keisuke Nagasaki Atsunori Tsuchiya Masahiko Yano Yasushi Tamura Masaaki Takamura Hirokazu Kawai Satoshi Yamagiwa Toru Kikuchi Minoru Nomoto Yutaka Aoyagi 《World Journal of Gastroenterology》 SCIE CAS CSCD 2010年第23期2918-2925,共8页
AIM:To investigate whether a noninvasive measurement of tissue strain has a potential usefulness for management of nonalcoholic steatohepatitis(NASH).METHODS:In total 26 patients,23 NASHs and 3 normal controls were en... AIM:To investigate whether a noninvasive measurement of tissue strain has a potential usefulness for management of nonalcoholic steatohepatitis(NASH).METHODS:In total 26 patients,23 NASHs and 3 normal controls were enrolled in this study.NASH was staged based on Brunt criterion.At a region of interest(ROI),a shear wave was evoked by implementing an acoustic radiation force impulse(ARFI),and the propagation velocity was quantif ied.RESULTS:Shear wave velocity(SWV) could be reproducibly quantified at all ROIs in all subjects except for 4 NASH cases,in which a reliable SWV value was not calculated at several ROIs.An average SWV of 1.34 ± 0.26 m/s in fibrous stage 0-1 was significantly slower than 2.20 ± 0.74 m/s and 2.90 ± 1.01 m/s in stages 3 and 4,respectively,but was not significantly different from 1.79 ± 0.78 m/s in stage 2.When a cutoff value was set at 1.47 m/s,receiver operating characteristic analysis showed significance to dissociate stages 3 and 4 from stage 0-1(P=0.0092) with sensitivity,specificity and area under curve of 100%,75% and 94.2%,respectively.In addition,the correlation between SWV and hyaluronic acid was significant(P<0.0001),while a tendency toward negative correlation was observed with serum albumin(P=0.053).CONCLUSION:The clinical implementation of ARFI provides noninvasive repeated evaluations of liver stiffness at an arbitrary position,which has the potential to shed new light on NASH management. 展开更多
关键词 Nonalcoholic steatohepatitis ULTRASOUND Liver stiffness measurement shear wave velocity Acoustic radiation force impulse
下载PDF
Shear wave velocity-based liquefaction evaluation in the great Wenchuan earthquake: a preliminary case study 被引量:9
18
作者 Zhou Yanguo,Chen Yunmin and Ling Daosheng MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering,Institute of Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China Assistant Professor Professor 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2009年第2期231-239,共9页
The great Wenchuan earthquake (Ms= 8.0) in 2008 caused severe damage in the western part of the Chengdu Plain. Soil liquefaction was one of the major causes of damage in the plain areas, and proper evaluation of liq... The great Wenchuan earthquake (Ms= 8.0) in 2008 caused severe damage in the western part of the Chengdu Plain. Soil liquefaction was one of the major causes of damage in the plain areas, and proper evaluation of liquefaction potential is important in the definition of the seismic hazard facing a given region and post-earthquake reconstruction. In this paper, a simplified procedure is proposed for liquefaction assessment of sandy deposits using shear wave velocity (V), and soil liquefaction from the Banqiao School site was preliminarily investigated after the earthquake. Boreholes were made at the site and shear wave velocities were measured both by SASW and down-hole methods. Based on the in-situ soil information and V profiles, the liquefaction potential of this site was evaluated. The results are reasonably consistent with the actual field behavior observed after the earthquake, indicating that the proposed procedure is effective. The possible effects of gravel and fines contents on liquefaction of sandy soils were also briefly discussed. 展开更多
关键词 LIQUEFACTION Wenchuan earthquake shear wave velocity spectral analysis of surface waves (SASW) hazarddefinition
下载PDF
Shear wave velocity-based evaluation and design of stone column improved ground for liquefaction mitigation 被引量:7
19
作者 Zhou Yanguo Sun Zhengbo +2 位作者 Chen Jie Chen Yunmin Chen Renpeng 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2017年第2期247-261,共15页
The evaluation and design of stone column improvement ground for liquefaction mitigation is a challenging issue for the state of practice. In this paper, a shear wave velocity-based approach is proposed based on the w... The evaluation and design of stone column improvement ground for liquefaction mitigation is a challenging issue for the state of practice. In this paper, a shear wave velocity-based approach is proposed based on the well-defined correlations of liquefaction resistance (CRR)-shear wave velocity (V)-void ratio (e) of sandy soils, and the values of parameters in this approach are recommended for preliminary design purpose when site specific values are not available. The detailed procedures of pre- and post-improvement liquefaction evaluations and stone column design are given. According to this approach, the required level of ground improvement will be met once the target V of soil is raised high enough (i.e., no less than the critical velocity) to resist the given earthquake loading according to the CRR-V relationship, and then this requirement is transferred to the control of target void ratio (i.e., the critical e) according to the V-e relationship. As this approach relies on the densification of the surrounding soil instead of the whole improved ground and is conservative by nature, specific considerations of the densification mechanism and effect are given, and the effects of drainage and reinforcement of stone columns are also discussed. A case study of a thermal power plant in Indonesia is introduced, where the effectiveness of stone column improved ground was evaluated by the proposed V-based method and compared with the SPT-based evaluation. This improved ground performed well and experienced no liquefaction during subsequent strong earthquakes. 展开更多
关键词 Liquefaction mitigation Stone column shear wave velocity Void ratio DENSIFICATION Ageing effect
下载PDF
上一页 1 2 187 下一页 到第
使用帮助 返回顶部