Ultrasonic backscatter technique has shown promise as a noninvasive cancellous bone assessment tool. A novel ultrasonic backscatter bone diagnostic （UBBD） instrument and an in vivo application for neonatal bone eval...Ultrasonic backscatter technique has shown promise as a noninvasive cancellous bone assessment tool. A novel ultrasonic backscatter bone diagnostic （UBBD） instrument and an in vivo application for neonatal bone evaluation are introduced in this study. The UBBD provides several advantages, including noninvasiveness, non- ionizing radiation, portability, and simplicity. In this study, the backscatter signal could be measured within 5 s using the UBBD. Ultrasonic backscatter measurements were performed on 467 neonates （268 males and 199 females） at the left calcaneus. The backscatter signal was measured at a central frequency of 3.5 MHz. The delay （-/-1） and duration （7-2） of the backscatter signal of interest （SOl） were varied, and the apparent integrated backscatter （AIB）, frequency slope of apparent backscatter （FSAB）, zero frequency intercept of apparent backscatter （FIAB）, and spectral centroid shift （SCS） were calculated. The results showed that the SOl selection had a direct influence on cancellous bone evaluation. The AIB and FIAB were positively correlated with the gestational age （｜R｜ up to 0.45, P 〈 0.001） when -/-1 was short （〈 8 μS）, while negative correlations （｜R｜ up to 0.56, P 〈 0.001） were commonly observed for T1 〉 10 IJS. Moderate positive correlations （IRI up to 0.45, P 〈 0.001） were observed for FSAB and SCS with gestational age when 71 was long （〉 10 μs）. The 7-2 mainly introduced fluctuations in the observed correlation coefficients. The moderate correlations observed with UBBD demonstrate the feasibility of using the backscatter signal to evaluate neonatal bone status. This study also proposes an explicit standard for in vivo SOl selection and neonatal cancellous bone assessment.展开更多
The micro orientation theological behavior of AZ61 Mg alloy during net-shape forming of tensile specimens via close-die pressing of extruded preformed and the effect of the press deformation rate on the microstructure...The micro orientation theological behavior of AZ61 Mg alloy during net-shape forming of tensile specimens via close-die pressing of extruded preformed and the effect of the press deformation rate on the microstructure characteristics were characterized with electron back-scattering diffraction(EBSD)orientation imaging microscopy and metallography.The results indicate that the intensity distribution of basal{0001}<1010>texture on the cross-section of the extruded perform is uniform and parallel to the extrusion direction.Subjected to pressing in extrusion direction,deformation shear stress leads to grain rotation and basal texture {0001}<1010>deviation from the extrusion direction,spreading in the direction perpendicular to pressing direction.The texture intensity increases with the press deformation rate and reaches its peak value at 50%,which is considerably lower than the value reached in extrusion deformation.Then,the texture intensity decreases with the press deformation rate reversely.展开更多
Elastic reverse-time migration can effectively deal with multicomponent seismic data in which the imaging condition based on energy norm can extract the scalar-imaging result from multicomponent data.However,the energ...Elastic reverse-time migration can effectively deal with multicomponent seismic data in which the imaging condition based on energy norm can extract the scalar-imaging result from multicomponent data.However,the energy cross-correlation imaging condition characterized by particle velocity and stress suffers from the problem of overdependence on the background elastic parameters.Therefore,we characterize the elastic-wave energy using the energy-flow vector,which is equal to the energy density,without background elastic parameters.According to the source and receiver wave fields,we propose an imaging energyflow vector and an elastic-wave energy imaging condition.Under the assumption of a planewave solution,the backscattering suppression is verified.The numerical simulations show that the elastic-energy imaging condition can obtain the energy image without backscattering.Compared with the cross-correlation imaging conditions in a vector-based wave field,the proposed imaging condition can eliminate the dependence on the background elastic parameters and effectively process seabed multicomponent data,which are conducive to further providing an interpretation of marine geological structures.展开更多
The mechanical and microstructural properties as well as crystallographic textures of asymmetrically rolled low carbon steel were studied.The modelling of plastic deformation was carried out in two scales:in the macro...The mechanical and microstructural properties as well as crystallographic textures of asymmetrically rolled low carbon steel were studied.The modelling of plastic deformation was carried out in two scales:in the macro-scale,using the finite elements method,and in the crystallographic scale,using the polycrystalline deformation model.The internal stress distribution in the rolling gap was calculated using the finite elements method and these stresses were then applied to the polycrystalline elasto-plastic deformation model.Selected mechanical properties,namely residual stress distribution,deformation work,applied force and torques,and bend amplitude,were calculated.The diffraction measurements,X-ray and electron backscatter diffraction,enabled the examination of texture heterogeneity and selected microstructure characteristics.The predicted textures agree well with those determined experimentally.The plastic anisotropy of cold rolled ferritic steel samples,connected with texture,was expressed by Lankford coefficient.展开更多
基金supported by the National Natural Science Foundation of China (11174060, 11327405, and 11504057)the Science and Technology Support Program of Shanghai (13441901900)+1 种基金the PhD Programs Foundation of the Ministry of Education of China (20130071110020)the China Postdoctoral Science Foundation (2015M571490)
文摘Ultrasonic backscatter technique has shown promise as a noninvasive cancellous bone assessment tool. A novel ultrasonic backscatter bone diagnostic （UBBD） instrument and an in vivo application for neonatal bone evaluation are introduced in this study. The UBBD provides several advantages, including noninvasiveness, non- ionizing radiation, portability, and simplicity. In this study, the backscatter signal could be measured within 5 s using the UBBD. Ultrasonic backscatter measurements were performed on 467 neonates （268 males and 199 females） at the left calcaneus. The backscatter signal was measured at a central frequency of 3.5 MHz. The delay （-/-1） and duration （7-2） of the backscatter signal of interest （SOl） were varied, and the apparent integrated backscatter （AIB）, frequency slope of apparent backscatter （FSAB）, zero frequency intercept of apparent backscatter （FIAB）, and spectral centroid shift （SCS） were calculated. The results showed that the SOl selection had a direct influence on cancellous bone evaluation. The AIB and FIAB were positively correlated with the gestational age （｜R｜ up to 0.45, P 〈 0.001） when -/-1 was short （〈 8 μS）, while negative correlations （｜R｜ up to 0.56, P 〈 0.001） were commonly observed for T1 〉 10 IJS. Moderate positive correlations （IRI up to 0.45, P 〈 0.001） were observed for FSAB and SCS with gestational age when 71 was long （〉 10 μs）. The 7-2 mainly introduced fluctuations in the observed correlation coefficients. The moderate correlations observed with UBBD demonstrate the feasibility of using the backscatter signal to evaluate neonatal bone status. This study also proposes an explicit standard for in vivo SOl selection and neonatal cancellous bone assessment.
基金Project(CSTC2007AA4008)supported by the Scientific and Technological Project in Chongqing of China
文摘The micro orientation theological behavior of AZ61 Mg alloy during net-shape forming of tensile specimens via close-die pressing of extruded preformed and the effect of the press deformation rate on the microstructure characteristics were characterized with electron back-scattering diffraction(EBSD)orientation imaging microscopy and metallography.The results indicate that the intensity distribution of basal{0001}<1010>texture on the cross-section of the extruded perform is uniform and parallel to the extrusion direction.Subjected to pressing in extrusion direction,deformation shear stress leads to grain rotation and basal texture {0001}<1010>deviation from the extrusion direction,spreading in the direction perpendicular to pressing direction.The texture intensity increases with the press deformation rate and reaches its peak value at 50%,which is considerably lower than the value reached in extrusion deformation.Then,the texture intensity decreases with the press deformation rate reversely.
基金supported by the National Nature Science Foundation of China(No.61801275)Shangdong Provincial Natural Science Foundation(No.ZR2018BF002)+2 种基金China Postdoctoral Science Foundation(No.2017M622242)Basic Research Projects of Science,Education and Industry Integration Pilot Project of Qilu University of Technology(2022PX082)Qingdao Applied Research Projects.
文摘Elastic reverse-time migration can effectively deal with multicomponent seismic data in which the imaging condition based on energy norm can extract the scalar-imaging result from multicomponent data.However,the energy cross-correlation imaging condition characterized by particle velocity and stress suffers from the problem of overdependence on the background elastic parameters.Therefore,we characterize the elastic-wave energy using the energy-flow vector,which is equal to the energy density,without background elastic parameters.According to the source and receiver wave fields,we propose an imaging energyflow vector and an elastic-wave energy imaging condition.Under the assumption of a planewave solution,the backscattering suppression is verified.The numerical simulations show that the elastic-energy imaging condition can obtain the energy image without backscattering.Compared with the cross-correlation imaging conditions in a vector-based wave field,the proposed imaging condition can eliminate the dependence on the background elastic parameters and effectively process seabed multicomponent data,which are conducive to further providing an interpretation of marine geological structures.
基金Projects(DEC-2011/01/B/ST8/07394,DEC-2011/01/D/ST8/07399)supported by the Polish National Centre for Science(NCN)The support of the Polish Ministry of Science and Higher Education and of the French ANR 05-BLAN-0383 project
文摘The mechanical and microstructural properties as well as crystallographic textures of asymmetrically rolled low carbon steel were studied.The modelling of plastic deformation was carried out in two scales:in the macro-scale,using the finite elements method,and in the crystallographic scale,using the polycrystalline deformation model.The internal stress distribution in the rolling gap was calculated using the finite elements method and these stresses were then applied to the polycrystalline elasto-plastic deformation model.Selected mechanical properties,namely residual stress distribution,deformation work,applied force and torques,and bend amplitude,were calculated.The diffraction measurements,X-ray and electron backscatter diffraction,enabled the examination of texture heterogeneity and selected microstructure characteristics.The predicted textures agree well with those determined experimentally.The plastic anisotropy of cold rolled ferritic steel samples,connected with texture,was expressed by Lankford coefficient.
