Different angle-resolved polarization configurations of Raman spectroscopy: A case on the basal and edge plane of two-dimensional materials

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.

Plane Elasticity and Dislocation of One-Dimensional Hexagonal Quasicrystals with Point Group 6

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.)

The occlusal plane in the facial context:inter-operator repeatability of a new three-dimensional method

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.

Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.

Detection of Congenital Uterine Malformation by Using Transvaginal Three-dimensional Ultrasound

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.

A generalized three-dimensional failure criterion for rock masses

The smooth convex generalized failure function, which represents 1/6 part of envelope in tile deviatoric plane, is proposed. The proposed function relies on four shape parameters （L, a, b and c）, in which two parameters （a and b） are dependent on the others. The parameter Ls is called extension ratio. The proposed failure function could be incorporated with any two-dimensional （2D） failure criteria to make it a three-dimensional （3D） version. In this paper, a mathematical formulation for incorporation of Hoek-Brown failure criterion with the proposed function is presented. The Hoek-Brown failure criterion is the most suited 2D failure criterion tbr geomaterials. Two types of analyses for best-fitting solution of published true tri-axial test data were made by considering （1） constant extension ratio and （2） variable extension ratio. The shape and strength parameters for different types of rocks have been determined by best-fitting the published true tri-axial test data for both the analyses. It is observed from the best-fitting solution by considering uniform extension ratio （L~） that shape constants have a correlation with Hoek-Brown strength parameters. Thus, only two parameters （c~. and m） are needed for representing the 3D failure criterion for intact rock. The statistical expression between shape and Hoek-Brown strength parameters is given. In the second analysis, when considering varying extension ratio, another parameterfis introduced. The modified extension ratio is related tofand extension ratio. The results at minimum mean misfit for all the nine rocks indicate that the range off varies from 0.7 to 1.0. It is found that mean misfit by considering varying extension ratio is lower than that in the first analysis. But it requires three parameters. A statistical expression betweenfand Hoek-Brown strength parameters has been established. Though coefficient of correlation is not reasonable, we may eliminate it as an extra parameter. At the end of the paper, a methodology has also been given for its application to isotropic jointed rock mass, so that it can be implemented in a numerical code for stability analysis of jointed rock mass structures.

Evaluation of Right Ventricular Volume and Systolic Function by Real-time Three-dimensional Echocardiography

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.

Infinite Three-Dimensional Coordination Polymers: Synthesis and Structures of [Cd (4,4'-bpy)_2 (H_2O)_2]_n (pic)_(2n),[Zn (4,4'-bpy)_2 (H_2O)_2]_n(pic)_(2n) (H_2O)_(2n), and [Zn (4,4'-bpy)_2 (H_2O)_2]_n (4,4'-bpy)_n(H_2O)_n (pic)_(2n)

Three Complexes of the formula [Cd (4,4'-bpy)_2 (H_2O)_2]_n. (pic)_(2n) (1) [Zn (4,4'-bpy)_2 (H_2O)]_n (4,4'-bpy)_n(H_2O)_n (pic)-(2n) (2) and [Zn (4,4'-bpy)_2 (H_2O)]_n (4,4'-bpy)_n (pic)-(2n)(H_2O)_n (3) (4.4'-bpy = 4.4'-bipyridine. pic = picric anion ) have been synthesized and characterized by elemental analysis and single-crystal x-ray diffraction. They all have infinite three-dimensional network structure. crystallizing in the monoclinic space group C2/c (1) and Cc (2.3).

Three dimensional K-Tz stress fields around the embedded center elliptical crack front in elastic plates

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.

A modified maximum tangential tensile stress criterion for three-dimensional crack propagation

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.

3-Dimensional Body Measurement Technology

3 - dimensional body measurement technology, the basis of developing high technology in industry, accelerates digital development of aplparel industry. This paper briefly introduces the history of 3 - dimensional body measurement technology, and recounts the principle and primary structure of some types of 3 - dimensional automatic body measurement system. With this understanding, it discusses prospect of 3- dimensional CAD and virtual technology used in apparel industry.

Three-Dimensional Stress Fields in Finite Thickness Plate with Hole Under Shear Load

The theoretical solutions are obtained for the three-dimensional(3-D)stress field in an infinite isotropic elastic plate with a through-the-thickness circular hole subjected to shear load at far field by using Kane and Mindlin′s assumption based on the stress function method.Based on the present solutions,the characteristics of 3-D stress field are analyzed and the emphasis is placed on the effects of the plate thickness and Poisson′s ratio on the deviation of the present 3-D in-plane stress from the related plane stress solutions,the stress concentration and the out-of-plane constraint.The present solutions show that the stress concentration factor reaches its peak value of about 8.9% which is higher than that of the plane stress solutions.As expected,the out-of-plane stress constraint factor can reach 1on the surface of the hole when the plate is a very thick one.

Comment on “Band gaps structure and semi-Dirac point of two-dimensional function photonic crystals” by Si-Qi Zhang et al.

Recently, Zhang et al. （Chin. Phys. B 26 024208 （2017）） investigated the band gap structures and semi-Dirac point of two-dimensional function photonic crystals, and the equations for the plane wave expansion method were induced to obtain the band structures. That report shows the band diagrams with the effects of function coefficient k and medium column ra under TE and TM waves. The proposed results look correct at first glance, but the authors made some mistakes in their report. Thus, the calculated results in their paper are incorrect. According to our calculations, the errors in their report are corrected, and the correct band structures also are presented in this paper.

On Two-Dimensional Above-Barrier Penetration and Sub-Barrier Tunneling for Non-Relativistic Particles and Photons

We study the two-dimensional above-barrier penetration and the sub-barrier tunneling of non-relativistic particles and photons, described in the quasi-monochromatic approximation by simple plane waves. Our scheme represents the motion from the left free-motion zero-potential region to the right zero-potential region through the intermediate region with a one-dimensional rectangular potential barrier along the axis, normal to the both parallel interfaces between all three regions, and with the zero potential along the axis, parallel to the those interfaces. We have firstly obtained the analytical expressions for the infinite series of multiple internal and external reflections and also of multiple transmitted waves of particles and photons, with equal shifts between them along the interfaces for the above-barrier penetration and with various shifts between them in the case of the sub-barrier tunneling. Finally the Hartman and Fletcher effect for any transmitted wave is established.

基于三维点云计算的CO_(2)-水-岩反应程度量化表征方法

CO_(2)地质封存是减少大气中CO_(2)排放,降低温室效应的重要途径,CO_(2)注入含水地层中时,CO_(2)-水-岩反应可能引起岩石矿物的侵蚀,对CO_(2)地质封存安全性产生显著影响。在室内实验中,通过表征岩石表面的形貌特征可以有效地评估CO_(2)-水-岩反应程度,为CO_(2)地质封存的安全性评估提供科学依据。通过三维点云计算可以精确量化地表征CO_(2)-水-岩反应程度,这种方法首先运用三维激光扫描技术,构建岩石表面的三维模型,确定CO_(2)-水处理前岩石表面三维模型的基准面,并基于处理前的均方根粗糙度确定处理后岩石表面三维模型的基准面。基于三维模型点云信息,提出了两种不同的体积计算新方法,并通过对规则模型体积的计算比较了两种计算方法的准确性与适用性,可根据实际情况选择两种计算方法量化表征CO_(2)-水处理前后岩石表面的侵蚀体积。最后,以陕西省咸阳市某煤矿煤样为例,开展了CO_(2)-水-岩反应模拟试验,验证了计算的可行性。试验结果表明:该文提出的侵蚀体积计算方法可有效地量化表征CO_(2)-水-岩反应程度,CO_(2)-水处理后岩石表面不同区域的侵蚀差异性明显,岩石表面的侵蚀体积与均方根粗糙度之间存在显著的正比关系,随着均方根粗糙度的增大,侵蚀体积也相应上升。

Parametric study on single shot peening by dimensional analysis method incorporated with finite element method

Shot peening is a widely used surface treatment method by generating compressive residual stress near the surface of metallic materials to increase fatigue life and re- sistance to corrosion fatigue, cracking, etc. Compressive re- sidual stress and dent profile are important factors to eval- uate the effectiveness of shot peening process. In this pa- per, the influence of dimensionless parameters on maximum compressive residual stress and maximum depth of the dent were investigated. Firstly, dimensionless relations of pro- cessing parameters that affect the maximum compressive residual stress and the maximum depth of the dent were de- duced by dimensional analysis method. Secondly, the in- fluence of each dimensionless parameter on dimensionless variables was investigated by the finite element method. Fur- thermore, related empirical formulas were given for each di- mensionless parameter based on the simulation results. Fi- nally, comparison was made and good agreement was found between the simulation results and the empirical formula, which shows that a useful approach is provided in this pa- per for analyzing the influence of each individual parameter.

对比机械通气重症肺炎及普通肺炎患者右心功能及右心室-肺动脉耦联的斑点追踪超声评价

目的 对比机械通气重症肺炎及普通肺炎患者的右心功能超声指标及右心室-肺动脉耦联指标的二维斑点追踪成像(2D-STI)评估价值。方法 选取66例肺炎患者,根据重症肺炎临床标准分为重症肺炎组25例和普通肺炎组41例,另纳入20例健康人为对照组进行超声心动图检查。于心尖四腔心切面获取右心室中段内径(RVD)、三尖瓣环收缩期位移(TAPSE)、三尖瓣环收缩期峰速度(S’)、三尖瓣反流峰值流速(TRV);经剑突下获取下腔静脉(IVC)长轴内径(IVCD)并计算呼吸变异率(IVCV)并估测右房压(RAP),并计算肺动脉收缩压(PASP)。右心室-肺动脉耦联指标以三尖瓣环收缩期位移(tricuspid annular plane systolic excursion, TAPSE)和肺动脉收缩压(pulmonary artery systolic pressure, PASP)的比值(TAPSE/PASP)表示。应用二维斑点追踪成像(two-dimensional speckle tracking imaging, 2D-STI)技术获取右心室游离壁整体应变(RVLSfw),基底段应变(RVLSbas)、中段应变(RVLSmid)、心尖段应变(RVLSapi)。将RVLSfw纳入右心室-肺动脉耦联中获取新指标RVLSfw/PASP,比较组间差异并做相关性分析。结果 重症肺炎组RVD、IVCD、TRV、PASP均高于普通肺炎组和对照组,IVCV、TAPSE均低于普通肺炎组和对照组(P<0.05),重症肺炎组S’低于普通肺炎组(P<0.05);普通肺炎组RVD、IVCD高于对照组(P<0.05)。2D-STI指标:重症肺炎组RVLSfw、RVLSbas和RVLSapi均低于普通肺炎组和对照组(P<0.05),普通肺炎组和对照组之间该指标无统计学意义(P>0.05);右心室-肺动脉耦联指标:重症肺炎组TAPSE/PASP、S’/PASP和RVLSfw/PASP均低于普通肺炎组和对照组,普通肺炎组和对照组之间该指标差异无统计学意义(P>0.05)。相关性分析显示:RVLSfw/PASP和TAPSE/PASP呈强相关(r=0.927,P<0.05)。结论 2D-STI指标和右心室-肺动脉耦联均对接受机械通气的重症肺炎患者的右心功能评估有一定价值,RVLSfw/PASP可作为评估右心室-肺动脉耦联的可靠指标。

THE 3-D STRESS INTENSITY FACTOR FOR A HALF PLANE CRACK IN A TRANSVERSELY ISOTROPIC SOLID DUE TO THE MOTION OF LOADS ON THE CRACK FACES

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.

Investigation on Porosity and In-plane Water Permeability of Nonwoven Geotextiles

Nonwoven geotextiles have been widely used as drains orfilters in many civil engineerings.The hydraulic charac-teristics of geotextiles are the basic function in these ap-plications.The in-plane permeability of nonwoven geo-textiles was discussed in this paper.The results of in-plane permeability coefficient of nonwoven geotextilesfrom measurement were analyzed.

复合材料z-pin增强技术研究现状

简要介绍了复合材料三维增强的方法及优缺点,重点综述复合材料z-pin增强技术的国内外研究现状及其应用技术。同时,对今后z-pin增强技术的发展提供了一些建议。