Angle-resolved polarized Raman(ARPR) spectroscopy can be utilized to assign the Raman modes based on crystal symmetry and Raman selection rules and also to characterize the crystallographic orientation of anisotropi...Angle-resolved polarized Raman(ARPR) spectroscopy can be utilized to assign the Raman modes based on crystal symmetry and Raman selection rules and also to characterize the crystallographic orientation of anisotropic materials.However, polarized Raman measurements can be implemented by several different configurations and thus lead to different results. In this work, we systematically analyze three typical polarization configurations: 1) to change the polarization of the incident laser, 2) to rotate the sample, and 3) to set a half-wave plate in the common optical path of incident laser and scattered Raman signal to simultaneously vary their polarization directions. We provide a general approach of polarization analysis on the Raman intensity under the three polarization configurations and demonstrate that the latter two cases are equivalent to each other. Because the basal plane of highly ordered pyrolytic graphite(HOPG) exhibits isotropic feature and its edge plane is highly anisotropic, HOPG can be treated as a modelling system to study ARPR spectroscopy of twodimensional materials on their basal and edge planes. Therefore, we verify the ARPR behaviors of HOPG on its basal and edge planes at three different polarization configurations. The orientation direction of HOPG edge plane can be accurately determined by the angle-resolved polarization-dependent G mode intensity without rotating sample, which shows potential application for orientation determination of other anisotropic and vertically standing two-dimensional materials and other materials.展开更多
The repeatability of a non-invasive digital protocol proposed to evaluate the three-dimensional(3D) position of the occlusal plane in the face is assessed.Dental virtual models and soft tissue facial morphology of 2...The repeatability of a non-invasive digital protocol proposed to evaluate the three-dimensional(3D) position of the occlusal plane in the face is assessed.Dental virtual models and soft tissue facial morphology of 20 adult subjects were digitally integrated using a 3D stereophotogrammetric imaging system.The digital 3D coordinates of facial and dental landmarks were obtained by two different operators.Camper's(facial) and occlusal(dental) planes were individuated,and their 3D relationships were measured.The repeatability of the protocol was investigated and showed no significant differences in repeated digitizations.The angle between occlusal and Camper's planes was smaller than 26 in the frontal and horizontal projections.In the sagittal projection,the angle was observed to be,on average,4.9 6.The determined occlusal plane pitch,roll and yaw values show good agreement with previously published data obtained by different protocols.The current non-invasive method was repeatable,without inter-operator differences and can facilitate assessment of healthy subjects.展开更多
Plane elasticity theory of one-dimensional hexagonal quasicrystals with point group 6 is proposed and established. As an application of this theory, one typical example of dislocation problem in the quasicrystals is i...Plane elasticity theory of one-dimensional hexagonal quasicrystals with point group 6 is proposed and established. As an application of this theory, one typical example of dislocation problem in the quasicrystals is investigated and its exact analytic solution is presented. The result obtained indicates that the stress components of (elastic) fields of a straight dislocation in the quasicrystals still first order singularity, which is the same as the (general crystals,) but are related with the Burgers vector of phason fields, which is different from the general (crystals.)展开更多
In this paper,the results of spectral description and invertibility of upper triangle infinite-dimensionalHamiltonian operators with a diagonal domain are given.By the above results,it is proved that the infinite-dime...In this paper,the results of spectral description and invertibility of upper triangle infinite-dimensionalHamiltonian operators with a diagonal domain are given.By the above results,it is proved that the infinite-dimensionalHamiltonian operator associated with plane elasticity equations without the body force is invertible,and the spectrumof which is non-empty and is a subset of R.展开更多
The indirect boundary element method(IBEM)is used to study three-dimensional scattering of obliquely incident plane SH waves by an alluvial valley embedded in a layered half-space.The free-field response of the layere...The indirect boundary element method(IBEM)is used to study three-dimensional scattering of obliquely incident plane SH waves by an alluvial valley embedded in a layered half-space.The free-field response of the layered half-space is calculated by the direct stiffness method,and dynamic Green's functions of moving distributed loads acting on inclined lines in a layered half-space are calculated to simulate the scattering wave field.The presented method yields very accurate results since the three-dimensional dynamic stiffness matrix is exact and the moving distributed loads can act directly on the valley boundary without singularity.Numerical results and analyses are performed for amplification of obliquely incident plane SH waves around an alluvial valley in a uniform half-space and in single layer over half-space.The results show that the three-dimensional responses are distinctly different from the two-dimensional responses,and the displacement amplitudes around alluvial valleys in a uniform half-space are obviously different from those in a layered half-space.展开更多
This study assessed the clinical application of transvaginal three-dimensional ultrasound (3D TVUS) in the diagnosis of congenital uterine malformation. A retrospective study was performed on 62 patients with congen...This study assessed the clinical application of transvaginal three-dimensional ultrasound (3D TVUS) in the diagnosis of congenital uterine malformation. A retrospective study was performed on 62 patients with congenital uterine malformation confirmed hysteroscopically and/or laparoscopically. The patients were subjected to transvaginal two-dimensional ultrasound (2D TVUS) and 3D TVUS. The accuracy rate was compared between the two methods. The accuracy rate of 3D TVUS was (98.38%, 61/62), higher than that of 2D TVUS (80.65%, 50/62). 3D TVUS coronal plane imaging could demon- strate the internal shape of the endometrial cavity and the external contour of the uterine fundus. It al- lowed accurate measurement on the coronary plane, and could three-dimensionally show the image of cervical tube, thereby providing information for the diagnosis of some complex uterine malformation. 3D TVUS imaging can obtain comprehensive information of the uterus malformation, and it is superior to 2D TVUS for the diagnosis of congenital uterine malformations, especially complex uterine anomaly.展开更多
The three-dimensional (3D) crack propagation is a hot issue in rock mechanics. To properly simulate 3D crack propagation, a modified maximum tangential tensile stress criterion is proposed. In this modified criterio...The three-dimensional (3D) crack propagation is a hot issue in rock mechanics. To properly simulate 3D crack propagation, a modified maximum tangential tensile stress criterion is proposed. In this modified criterion, it is supposed that cracks propagate only at crack front in the principal normal plane. The tangential tensile stress at crack front in the principal normal plane in local coordinates is employed to determine crack propagation, which is calculated through coordinate transformation from global to local coordinates. New cracks will propagate when the maximum tangential tensile stress at crack front in the principal normal plane reaches the tensile strength of rock-like materials. Compared with the previous crack propagation criteria, the modified crack propagation criterion is helpful in calculating 3D crack stress intensity factor, and can overcome the limitations of propagation step determined by individual experiences in previous studies. Finally, the 3D crack propagation process is traced by element-free Galerkin method. The numerical results agree well with the experimental ones for a frozen resin sample with prefabricated 3D cracks.展开更多
Through detailed three-dimensional (3D) finite element (FE) calculations, the out-of-plane constraints Tz along embedded center-elliptical cracks in mode I elastic plates are studied. The distributions of Tz are o...Through detailed three-dimensional (3D) finite element (FE) calculations, the out-of-plane constraints Tz along embedded center-elliptical cracks in mode I elastic plates are studied. The distributions of Tz are obtained near the crack front with aspect ratios (a/c) of 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0. Tz decreases from an approximate value of Poisson ratio v at the crack tip to zero with increasing normalized radial distances (r/a) in the normal plane of the crack front line, and increases gradually when the elliptical parameter angle φ changes from 0° to 90°at the same r/a. With a/c rising to 1.0, Tz is getting nearly independent of φ and is only related to r/a. Based on the present FE calculations for Tz, empirical formulas for Tz are obtained to describe the 3D distribution of Tz for embedded center-elliptical cracks using the least squares method in the range of 0.2 ≤ a/c ≤ 1.0. These Tz results together with the corresponding stress intensity factor K are well suitable for the analysis of the 3D embedded centerelliptical crack from field, and a two-parameter K-Tz principle is proposed.展开更多
The optimal plane for measurement of the right ventricular (RV) volumes by real-time three-dimensional echocardiography (RT3DE) was determined and the feasibility and accuracy of RT3DE in studying RV systolic function...The optimal plane for measurement of the right ventricular (RV) volumes by real-time three-dimensional echocardiography (RT3DE) was determined and the feasibility and accuracy of RT3DE in studying RV systolic function was assessed. RV “Full volume” images were acquired by RT3DE in 22 healthy subjects. RV end-diastolic volumes (RVEDV) and end-systolic volumes (RVESV) were outlined using apical biplane, 4-plane, 8-plane, 16-plane offline separately. RVSV and RVEF were calculated. Meanwhile tricuspid annual systolic excursion (TASE) was measured by M-mode echo. LVSV was outlined by 2-D echo according to the biplane Simpson's rule. The results showed: (1) There was a good correlation between RVSV measured from series planes and LVSV from 2-D echo (r=0.73; r=0.69; r=0.63; r=0.66, P<0.25—0.0025); (2) There were significant differences between RVEDV in biplane and those in 4-, 8-, 16-plane (P<0.001). There was also difference between RV volume in 4-plane and that in 8-plane (P<0.05), but there was no significant difference between RV volume in 8-plane and that in 16-plane (P>0.05); (3) Inter-observers and intro-observers variability analysis showed that there were close agreements and relations for RV volumes (r=0.986, P<0.001; r=0.93, P<0.001); (4) There was a significantly positive correlation of TASE to RVSV and RVEF from RT3DE (r=0.83; r=0.90). So RV volume measures with RT3DE are rapid, accurate and reproducible. In view of RV's complex shape, apical 8-plane method is better in clinical use. It may allow early detection of RV systolic function.展开更多
Three-dimensional analysis of a half plane crack in a transversely isotropic solid is performed. The crack is subjected to a pair of normal point loads moving in a direction perpendicular to the crack edge on its face...Three-dimensional analysis of a half plane crack in a transversely isotropic solid is performed. The crack is subjected to a pair of normal point loads moving in a direction perpendicular to the crack edge on its faces. Transform methods are used to reduce the boundary value problem to a single integral equation that can be solved by the Wiener-Hopf technique. The Cagniard-de Hoop method is employed to invert the transforms. An exact expression is derived for the mode I stress intensity factor as a function of time and position along the crack edge. Some features of the solution are discussed through numerical results.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2016YFA0301204)the National Natural Science Foundation of China(Grant Nos.11604326,11434010,11474277,and 11225421)
文摘Angle-resolved polarized Raman(ARPR) spectroscopy can be utilized to assign the Raman modes based on crystal symmetry and Raman selection rules and also to characterize the crystallographic orientation of anisotropic materials.However, polarized Raman measurements can be implemented by several different configurations and thus lead to different results. In this work, we systematically analyze three typical polarization configurations: 1) to change the polarization of the incident laser, 2) to rotate the sample, and 3) to set a half-wave plate in the common optical path of incident laser and scattered Raman signal to simultaneously vary their polarization directions. We provide a general approach of polarization analysis on the Raman intensity under the three polarization configurations and demonstrate that the latter two cases are equivalent to each other. Because the basal plane of highly ordered pyrolytic graphite(HOPG) exhibits isotropic feature and its edge plane is highly anisotropic, HOPG can be treated as a modelling system to study ARPR spectroscopy of twodimensional materials on their basal and edge planes. Therefore, we verify the ARPR behaviors of HOPG on its basal and edge planes at three different polarization configurations. The orientation direction of HOPG edge plane can be accurately determined by the angle-resolved polarization-dependent G mode intensity without rotating sample, which shows potential application for orientation determination of other anisotropic and vertically standing two-dimensional materials and other materials.
文摘The repeatability of a non-invasive digital protocol proposed to evaluate the three-dimensional(3D) position of the occlusal plane in the face is assessed.Dental virtual models and soft tissue facial morphology of 20 adult subjects were digitally integrated using a 3D stereophotogrammetric imaging system.The digital 3D coordinates of facial and dental landmarks were obtained by two different operators.Camper's(facial) and occlusal(dental) planes were individuated,and their 3D relationships were measured.The repeatability of the protocol was investigated and showed no significant differences in repeated digitizations.The angle between occlusal and Camper's planes was smaller than 26 in the frontal and horizontal projections.In the sagittal projection,the angle was observed to be,on average,4.9 6.The determined occlusal plane pitch,roll and yaw values show good agreement with previously published data obtained by different protocols.The current non-invasive method was repeatable,without inter-operator differences and can facilitate assessment of healthy subjects.
文摘Plane elasticity theory of one-dimensional hexagonal quasicrystals with point group 6 is proposed and established. As an application of this theory, one typical example of dislocation problem in the quasicrystals is investigated and its exact analytic solution is presented. The result obtained indicates that the stress components of (elastic) fields of a straight dislocation in the quasicrystals still first order singularity, which is the same as the (general crystals,) but are related with the Burgers vector of phason fields, which is different from the general (crystals.)
基金the National Natural Science Foundation of China under Grant No.10562002the Natural Science Foundation of Inner Mongolia under Grant No.200508010103
文摘In this paper,the results of spectral description and invertibility of upper triangle infinite-dimensionalHamiltonian operators with a diagonal domain are given.By the above results,it is proved that the infinite-dimensionalHamiltonian operator associated with plane elasticity equations without the body force is invertible,and the spectrumof which is non-empty and is a subset of R.
基金sponsored by Project of Natural Science Foundation of China(50908156,50978183)the Application Basis and Front Technology Research Progamme of Tianjin Municipality under Grant 12JCZDJC29000
文摘The indirect boundary element method(IBEM)is used to study three-dimensional scattering of obliquely incident plane SH waves by an alluvial valley embedded in a layered half-space.The free-field response of the layered half-space is calculated by the direct stiffness method,and dynamic Green's functions of moving distributed loads acting on inclined lines in a layered half-space are calculated to simulate the scattering wave field.The presented method yields very accurate results since the three-dimensional dynamic stiffness matrix is exact and the moving distributed loads can act directly on the valley boundary without singularity.Numerical results and analyses are performed for amplification of obliquely incident plane SH waves around an alluvial valley in a uniform half-space and in single layer over half-space.The results show that the three-dimensional responses are distinctly different from the two-dimensional responses,and the displacement amplitudes around alluvial valleys in a uniform half-space are obviously different from those in a layered half-space.
文摘This study assessed the clinical application of transvaginal three-dimensional ultrasound (3D TVUS) in the diagnosis of congenital uterine malformation. A retrospective study was performed on 62 patients with congenital uterine malformation confirmed hysteroscopically and/or laparoscopically. The patients were subjected to transvaginal two-dimensional ultrasound (2D TVUS) and 3D TVUS. The accuracy rate was compared between the two methods. The accuracy rate of 3D TVUS was (98.38%, 61/62), higher than that of 2D TVUS (80.65%, 50/62). 3D TVUS coronal plane imaging could demon- strate the internal shape of the endometrial cavity and the external contour of the uterine fundus. It al- lowed accurate measurement on the coronary plane, and could three-dimensionally show the image of cervical tube, thereby providing information for the diagnosis of some complex uterine malformation. 3D TVUS imaging can obtain comprehensive information of the uterus malformation, and it is superior to 2D TVUS for the diagnosis of congenital uterine malformations, especially complex uterine anomaly.
基金Supported by the National Natural Science Foundation of China (50979052,40872203, 41072234)the Provincial Natural Science Foundation of Shandong (ZR2009FM041,ZR2010EM032,ZR2009AZ001)
文摘The three-dimensional (3D) crack propagation is a hot issue in rock mechanics. To properly simulate 3D crack propagation, a modified maximum tangential tensile stress criterion is proposed. In this modified criterion, it is supposed that cracks propagate only at crack front in the principal normal plane. The tangential tensile stress at crack front in the principal normal plane in local coordinates is employed to determine crack propagation, which is calculated through coordinate transformation from global to local coordinates. New cracks will propagate when the maximum tangential tensile stress at crack front in the principal normal plane reaches the tensile strength of rock-like materials. Compared with the previous crack propagation criteria, the modified crack propagation criterion is helpful in calculating 3D crack stress intensity factor, and can overcome the limitations of propagation step determined by individual experiences in previous studies. Finally, the 3D crack propagation process is traced by element-free Galerkin method. The numerical results agree well with the experimental ones for a frozen resin sample with prefabricated 3D cracks.
基金The project supported by the National Natural Science Foundation of China (50275073)
文摘Through detailed three-dimensional (3D) finite element (FE) calculations, the out-of-plane constraints Tz along embedded center-elliptical cracks in mode I elastic plates are studied. The distributions of Tz are obtained near the crack front with aspect ratios (a/c) of 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0. Tz decreases from an approximate value of Poisson ratio v at the crack tip to zero with increasing normalized radial distances (r/a) in the normal plane of the crack front line, and increases gradually when the elliptical parameter angle φ changes from 0° to 90°at the same r/a. With a/c rising to 1.0, Tz is getting nearly independent of φ and is only related to r/a. Based on the present FE calculations for Tz, empirical formulas for Tz are obtained to describe the 3D distribution of Tz for embedded center-elliptical cracks using the least squares method in the range of 0.2 ≤ a/c ≤ 1.0. These Tz results together with the corresponding stress intensity factor K are well suitable for the analysis of the 3D embedded centerelliptical crack from field, and a two-parameter K-Tz principle is proposed.
文摘The optimal plane for measurement of the right ventricular (RV) volumes by real-time three-dimensional echocardiography (RT3DE) was determined and the feasibility and accuracy of RT3DE in studying RV systolic function was assessed. RV “Full volume” images were acquired by RT3DE in 22 healthy subjects. RV end-diastolic volumes (RVEDV) and end-systolic volumes (RVESV) were outlined using apical biplane, 4-plane, 8-plane, 16-plane offline separately. RVSV and RVEF were calculated. Meanwhile tricuspid annual systolic excursion (TASE) was measured by M-mode echo. LVSV was outlined by 2-D echo according to the biplane Simpson's rule. The results showed: (1) There was a good correlation between RVSV measured from series planes and LVSV from 2-D echo (r=0.73; r=0.69; r=0.63; r=0.66, P<0.25—0.0025); (2) There were significant differences between RVEDV in biplane and those in 4-, 8-, 16-plane (P<0.001). There was also difference between RV volume in 4-plane and that in 8-plane (P<0.05), but there was no significant difference between RV volume in 8-plane and that in 16-plane (P>0.05); (3) Inter-observers and intro-observers variability analysis showed that there were close agreements and relations for RV volumes (r=0.986, P<0.001; r=0.93, P<0.001); (4) There was a significantly positive correlation of TASE to RVSV and RVEF from RT3DE (r=0.83; r=0.90). So RV volume measures with RT3DE are rapid, accurate and reproducible. In view of RV's complex shape, apical 8-plane method is better in clinical use. It may allow early detection of RV systolic function.
基金The project supported by the Guangdong Provincial Natural Science Foundationthe Science Foundation of Shantou University
文摘Three-dimensional analysis of a half plane crack in a transversely isotropic solid is performed. The crack is subjected to a pair of normal point loads moving in a direction perpendicular to the crack edge on its faces. Transform methods are used to reduce the boundary value problem to a single integral equation that can be solved by the Wiener-Hopf technique. The Cagniard-de Hoop method is employed to invert the transforms. An exact expression is derived for the mode I stress intensity factor as a function of time and position along the crack edge. Some features of the solution are discussed through numerical results.