Instrumented experiments were conducted in concrete models to study the explosion-induced radial strain and fracture effect of rock-like media under confined explosion with a charge of cyclonite. As a charge was explo...Instrumented experiments were conducted in concrete models to study the explosion-induced radial strain and fracture effect of rock-like media under confined explosion with a charge of cyclonite. As a charge was exploded, two different radial strain waves were sequentially recorded by a strain gage at a distance of 80 mm from the center of charge. Through the attenuation formula of the maximum compressive strain(εrmax), the distribution of εrmax and its strain rate（ ） between the charge and gage were obtained. The effect of the two waves propagating outwards on the radial fracture of surrounding media was discussed. The results show that the two waves are pertinent to the loading of shock energy （Es） and bubble energy （Eb） against concrete surrounding charge, respectively. The former wave lasts for much shorter time than the latter. The peak values of εrmax and of the former are higher than those of the latter, respectively.展开更多
The left ventricular radial strain in the inner and outer layers was evaluated by using two-dimensional speckle tracking imaging （2DS）. Twenty-five piglets were studied. The short axis views were acquired. Peak syst...The left ventricular radial strain in the inner and outer layers was evaluated by using two-dimensional speckle tracking imaging （2DS）. Twenty-five piglets were studied. The short axis views were acquired. Peak systolic radial strain was measured from 6 circumferential points related to 6 standard segments in the inner and outer layers respectively using 2DS methods. The peak positive first derivative （dp/dt） of left ventricular pressure was compared to the radial strain from 2DS. The inner band showed higher peak radial strain values as compared to the outer band at all of the segments （P〈0.0001）, but the differences had significance just in anteroseptal, posterior, inferior and septal segments （P〈0.05）. Good correlation could be found between radial strain of inner and outer layers and peak dp/dt （P〈0.001）. These preliminary results showed that the degree of local deformation or wall thickening of the ventricular wall in its inner layer was more obvious than its outer layer. It is suggested that the 2DS technique is useful and sensitive for better understanding the regional and global myocar- dial motion and its relationship to the complex architecture of myocardium.展开更多
The strain behavior of 0.71 Pb(Mg_(1/3)Nb_(2/3))O_(3)ePbTiO_(3)(PMN-PT)single crystal prepared by a solidstate single crystal growth method was investigated on two most widely used orientations,i.e.,(001)-and(011)-ori...The strain behavior of 0.71 Pb(Mg_(1/3)Nb_(2/3))O_(3)ePbTiO_(3)(PMN-PT)single crystal prepared by a solidstate single crystal growth method was investigated on two most widely used orientations,i.e.,(001)-and(011)-oriented.A special emphasis was put on the correlation among longitudinal and transverse strains and the consequent volume change.We show that seemingly different strain behavior of(001)-and(011)-oriented crystals has the same origin,and the underlying mechanism excludes possible contribution from the frequently cited polarization rotation.In situ monitoring of electric field induced Poisson’s ratio further suggested that the polarization vectors contributing to the strain properties in PMN-PT are not confined to a unique direction forced by the crystallographic symmetry but possess a span of angular range.展开更多
文摘Instrumented experiments were conducted in concrete models to study the explosion-induced radial strain and fracture effect of rock-like media under confined explosion with a charge of cyclonite. As a charge was exploded, two different radial strain waves were sequentially recorded by a strain gage at a distance of 80 mm from the center of charge. Through the attenuation formula of the maximum compressive strain(εrmax), the distribution of εrmax and its strain rate（ ） between the charge and gage were obtained. The effect of the two waves propagating outwards on the radial fracture of surrounding media was discussed. The results show that the two waves are pertinent to the loading of shock energy （Es） and bubble energy （Eb） against concrete surrounding charge, respectively. The former wave lasts for much shorter time than the latter. The peak values of εrmax and of the former are higher than those of the latter, respectively.
文摘The left ventricular radial strain in the inner and outer layers was evaluated by using two-dimensional speckle tracking imaging （2DS）. Twenty-five piglets were studied. The short axis views were acquired. Peak systolic radial strain was measured from 6 circumferential points related to 6 standard segments in the inner and outer layers respectively using 2DS methods. The peak positive first derivative （dp/dt） of left ventricular pressure was compared to the radial strain from 2DS. The inner band showed higher peak radial strain values as compared to the outer band at all of the segments （P〈0.0001）, but the differences had significance just in anteroseptal, posterior, inferior and septal segments （P〈0.05）. Good correlation could be found between radial strain of inner and outer layers and peak dp/dt （P〈0.001）. These preliminary results showed that the degree of local deformation or wall thickening of the ventricular wall in its inner layer was more obvious than its outer layer. It is suggested that the 2DS technique is useful and sensitive for better understanding the regional and global myocar- dial motion and its relationship to the complex architecture of myocardium.
基金supported by the Leading Foreign Research Institute Recruitment Program(No.2017K1A4A3015437)through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT.SGL acknowledges the financial support from Defense Agency for Technology and Quality(DTaQ,E 180001)。
文摘The strain behavior of 0.71 Pb(Mg_(1/3)Nb_(2/3))O_(3)ePbTiO_(3)(PMN-PT)single crystal prepared by a solidstate single crystal growth method was investigated on two most widely used orientations,i.e.,(001)-and(011)-oriented.A special emphasis was put on the correlation among longitudinal and transverse strains and the consequent volume change.We show that seemingly different strain behavior of(001)-and(011)-oriented crystals has the same origin,and the underlying mechanism excludes possible contribution from the frequently cited polarization rotation.In situ monitoring of electric field induced Poisson’s ratio further suggested that the polarization vectors contributing to the strain properties in PMN-PT are not confined to a unique direction forced by the crystallographic symmetry but possess a span of angular range.
