Numerical Method Based on Compatible Manifold Element for Thin Plate Bending

The typical quadrangular and triangular elements for thin plate bending based on Kirchhoff assumptions are the non- conforming elements with low computational accuracy and limitative application range in fmite element method（FEM）. Some compatible elements can be developed by the means of supplementing correction functions, increasing nodes in element or on the boundaries, expanding nodal degrees of freedom（DOF）, etc, but these elements are inconvenient to apply in practice for the high calculation complexity. In this paper, in order to overcome the defects of thin plate bending finite element, numerical manifold method（NMM） was introduced to solve thin plate bending deformation problem. Rectangular mesh was adopted as mathematical mesh to form f＇mite element cover system, and then 16-cover manifold element was proposed. Numerical manifold formulas were constructed on the basis of minimum potential energy principle, displacement boundary conditions are implemented by penalty function method, and all the element matrixes were derived in details. The 16-cover element has a simple calculation process for employing only the transverse displacement cover DOFs as the basic unknown variables, and has been proved to meet the requirements of completeness and full compatibility. As an application, the presented 16-cover element has been used to analyze bending deformation of square thin plate under different loads and boundary conditions, and the results show that numerical manifold method with compatible element, compared with finite element method, can improve computational accuracy and convergence greatly.

MIXED COMPATIBLE ELEMENT AND MIXED HYBRID INCOMPATIBLE ELEMENT VARIATIONAL METHODS IN DYNAMICS OF VISCOUS BAROTROPIC FLUIDS

This paper presents and proves the mixed compatible finite element variationalprinciples in dynamics of viscous barotropic fluids. When the principles are proved, itis found that the compatibility conditions of stress can be naturally satisfied. The gene-rallzed variational principles with mixed hybrid incompatible finite elements are alsopresented and proved, and they can reduce the computation of incompatible elements indynamics of viscous barotropic flows.

THE APPLICATION OF COMPATIBLE STRESS ITERATIVE METHOD IN DYNAMIC FINITE ELEMENT ANALYSIS OF HIGH VELOCITY IMPACT

There is a common difficulty in elastic-plastic impact codes such as EPIC[2,3] NONSAP[4], etc.. Most of these codes use the simple linear functions usually taken from static problem to represent the displacement components. In such finite element formulation, the stress components are constant in each element and they are discontinuous in any two neighboring elements. Therefore, the bases of using the virtual work principle in such elements are unreliable. In this paper, we introduce a new method, namely, the compatible stress iterative method, to eliminate the above-said difficulty. The calculated examples show that the calculation using the new method in dynamic finite element analysis of high velocity impact is valid and stable, and the element stiffness can be somewhat reduced.

Inference of phylogenetic relationships among key angiosperm lineages using a compatibility method on a molecular data set

Phylogenetic relationships among the five key angiosperm lineages, Ceratophyllum, Chloranthaceae, eudicots, magnoliids, and monocots, have resisted resolution despite several large-scale analyses sampling taxa and characters extensively and using various analytical methods. Meanwhile, compatibility methods, which were explored together with parsimony and likelihood methods during the early development stage of phylogenetics, have been greatly under-appreciated and not been used to analyze the massive amount of sequence data to recon-struct the basal angiosperm phylogeny. In this study, we used a compatibility method on a data set of eight genes (mitochondrial atp1, matR, and nad5, plastid atpB, matK, rbcL, and rpoC2, and nuclear 18S rDNA) gathered in an earlier study. We selected two sets of characters that are compatible with more of the other characters than a random character would be with at probabilities of pM<0.1 and pM<0.5 respectively. The resulting data matrices were subjected to parsimony and likelihood bootstrap analyses. Our unrooted parsimony analyses showed that Cerato-phyllum was immediately related to eudicots, this larger lineage was immediately related to magnoliids, and monocots were closely related to Chloranthaceae. All these relationships received 76%–96% bootstrap support. A likelihood analysis of the 8 gene pM<0.5 compatible site matrix recovered the same topology but with low support. Likelihood analyses of other compatible site matrices produced different topologies that were all weakly sup-ported. The topology reconstructed in the parsimony analyses agrees with the one recovered in the previous study using both parsimony and likelihood methods when no character was eliminated. Parts of this topology have also been recovered in several earlier studies. Hence, this topology plausibly reflects the true relationships among the five key angiosperm lineages.

A hybrid subcell-remapping algorithm for staggered multi-material arbitrary Lagrangian-Eulerian methods

A new flux-based hybrid subcell-remapping algorithm for staggered multimaterial arbitrary Lagrangian-Eulerian (MMALE) methods is presented. This new method is an effective generalization of the original subcell-remapping method to the multi-material regime (LOUBERE, R. and SHASHKOV,M. A subcell remapping method on staggered polygonal grids for arbitrary-Lagrangian-Eulerian methods. Journal of Computational Physics, 209, 105–138 (2005)). A complete remapping procedure of all fluid quantities is described detailedly in this paper. In the pure material regions, remapping of mass and internal energy is performed by using the original subcell-remapping method. In the regions near the material interfaces, remapping of mass and internal energy is performed with the intersection-based fluxes where intersections are performed between the swept regions and pure material polygons in the Lagrangian mesh, and an approximate approach is then introduced for constructing the subcell mass fluxes. In remapping of the subcell momentum, the mass fluxes are used to construct the momentum fluxes by multiplying a reconstructed velocity in the swept region. The nodal velocity is then conservatively recovered. Some numerical examples simulated in the full MMALE regime and several purely cyclic remapping examples are presented to prove the properties of the remapping method.

ITSTUDIES ON THE EFFECT OF UREA ON THE COMPATIBILITY OF PMMA/PVC MIXTURES IN DMF BY A DILUTE- SOLUTION VISCOMETRY METHOD

The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△b_m and △[η]_m). It wasfound that the compatibility of the polymer mixtures is decreased with increasing urea addition, passing through a minimumat 0.5 M urea.

Single-Step Arbitrary Lagrangian-Eulerian Discontinuous Galerkin Method for 1-D Euler Equations

We propose an explicit,single-step discontinuous Galerkin method on moving grids using the arbitrary Lagrangian-Eulerian approach for one-dimensional Euler equations.The grid is moved with the local fluid velocity modified by some smoothing,which is found to con-siderably reduce the numerical dissipation introduced by Riemann solvers.The scheme preserves constant states for any mesh motion and we also study its positivity preservation property.Local grid refinement and coarsening are performed to maintain the mesh qual-ity and avoid the appearance of very small or large cells.Second,higher order methods are developed and several test cases are provided to demonstrate the accuracy of the proposed scheme.

Negative Norm Estimates for Arbitrary Lagrangian-Eulerian Discontinuous Galerkin Method for Nonlinear Hyperbolic Equations

In this paper,we present the negative norm estimates for the arbitrary Lagrangian-Eulerian discontinuous Galerkin(ALE-DG)method solving nonlinear hyperbolic equations with smooth solutions.The smoothness-increasing accuracy-conserving(SIAC)filter is a post-processing technique to enhance the accuracy of the discontinuous Galerkin(DG)solutions.This work is the essential step to extend the SIAC filter to the moving mesh for nonlinear problems.By the post-processing theory,the negative norm estimates are vital to get the superconvergence error estimates of the solutions after post-processing in the L2 norm.Although the SIAC filter has been extended to nonuniform mesh,the analysis of fil-tered solutions on the nonuniform mesh is complicated.We prove superconvergence error estimates in the negative norm for the ALE-DG method on moving meshes.The main dif-ficulties of the analysis are the terms in the ALE-DG scheme brought by the grid velocity field,and the time-dependent function space.The mapping from time-dependent cells to reference cells is very crucial in the proof.The numerical results also confirm the theoreti-cal proof.

Higher Order Collocation Methods for Nonlocal Problems and Their Asymptotic Compatibility

We study the convergence and asymptotic compatibility of higher order collocation methods for nonlocal operators inspired by peridynamics,a nonlocal formulation of continuum mechanics.We prove that the methods are optimally convergent with respect to the polynomial degree of the approximation.A numerical method is said to be asymptotically compatible if the sequence of approximate solutions of the nonlocal problem converges to the solution of the corresponding local problem as the horizon and the grid sizes simultaneously approach zero.We carry out a calibration process via Taylor series expansions and a scaling of the nonlocal operator via a strain energy density argument to ensure that the resulting collocation methods are asymptotically compatible.We fnd that,for polynomial degrees greater than or equal to two,there exists a calibration constant independent of the horizon size and the grid size such that the resulting collocation methods for the nonlocal difusion are asymptotically compatible.We verify these fndings through extensive numerical experiments.

Free-Interface Dual-Compatibility Modal Synthesis Substructure Method in Large-Scale Structures

Free-interface dual-compatibility modal synthesis method(compatibility of both force and displacement on interfaces)is introduced to large-scale civil engineering structure to enhance computation efficiency. The basic equations of the method are first set up, and then the mode cut-off principle and the dividing principle are proposed. MATLAB is used for simulation in different frame structures. The simulation results demonstrate the applicability of this substructure method to civil engineering structures and the correctness of the proposed mode cut-off principle. Studies are also conducted on how to divide the whole structure for better computation efficiency while maintaining better precision. It is observed that the geometry and material properties should be considered, and the synthesis results would be more precise when the inflection points of the mode shapes are taken into consideration. Furthermore, the simulation performed on a large-scale high-rise connected structure further proves the feasibility and efficiency of this modal synthesis method compared with the traditional global method. It is also concluded from the simulation results that the fewer number of DOFs in each substructure will result in better computation efficiency, but too many substructures will be time-consuming due to the tedious synthesis procedures. Moreover, the substructures with free interface will introduce errors and reduce the precision dramatically, which should be avoided.

Analysis and Simulation of the Influence of Electromagnetic Fields on Living Beings near HV Power Lines Using the FDTD Method

Recent decades have seen rapid advances in the field of electrical engineering, such that our environment has become a sea of electrical and magnetic signals, raising questions about the possible effects of low-frequency electromagnetic fields on the environment and which are capable of modifying and destroying our ecosystem. Particular interest was given in this article due to a massive influx of population living near high voltage lines. The analysis and simulation of the influence of low frequency electromagnetic fields on living beings in the vicinity of high voltage sources 132 kV and 220 kV in urban areas in DR Congo is the subject of our research with a view to estimating the level of exposure of humans to low frequency electromagnetic fields. To carry out our research, we used the classic method of analyzing the field produced near a high voltage line based on Maxwell’s image theory, the Maxwell-Gauss theorem and Maxwell-Ampère theorem to model and quantify low-frequency electromagnetic fields in the vicinity of high-voltage lines. The 2D FDTD numerical formulation was developed from telegraphers’ equations and allowed us to obtain models of current and voltage induced by electromagnetic fields on living beings below and near HV lines. The different simulations carried out on the proposed models illustrate the effects of the electrical and geometric parameters of the pylons on the distribution of the electromagnetic field in the vicinity of the HV lines. The results obtained were compared to the safety limits recommended by the standards.

精细化管理法减少中药注射剂不合理配伍的效果分析

目的:评价精细化管理法减少中药注射剂不合理配伍的效果。方法:通过鱼骨图分析可能影响中药注射剂不合理配伍的因素,针对关键问题实施精细化管理,调查精细化管理干预前(2021年7—12月)、干预后(2022年7—12月)该院中药注射剂医嘱,对不合理配伍医嘱进行统计分析,对比干预前后中药注射剂医嘱配伍不合理率,探讨干预措施的有效性。结果:干预前,25453组中药注射剂医嘱中,不合理配伍医嘱2366组,中药注射剂医嘱配伍不合理率为9.30%;干预后,28466组中药注射剂医嘱中,不合理配伍医嘱855组,中药注射剂医嘱配伍不合理率为3.00%,不合理率较干预前降低67.74%。干预后,中药注射剂医嘱中溶剂剂量不适宜、违反“十九畏”原则和溶剂种类选择不当问题大幅减少,未冲管和中西药混合输注问题已基本不存在。表明精细化管理模式能够有效改善中药注射剂医嘱不合理配伍情况。结论:通过鱼骨图分析可能影响中药注射剂不合理配伍的因素,针对关键问题实施精细化管理,可有效减少中药注射剂的不合理配伍现象,为其他医院中药注射剂的合理应用提供了参考。

肾俞穴穴性及用法新探

肾俞穴作为肾脏之气输注于背腰部的腧穴,其属于足太阳膀胱经范畴,在临床上广泛运用于生殖泌尿系统等疾病的治疗。该穴位于人体背部足太阳膀胱经直行支脉循行处,且为足少阴经脉之标部所在,故具有特殊的穴性。但当前对于肾俞穴穴性及运用缺乏深入研究。该文基于经脉、标本、四海等理论探究了其穴性,并通过古籍溯源及临床实践探究其疗效发挥与刺灸方法、穴位配伍、针刺深度等关系。结果表明,不同的刺灸方法、穴位配伍、针刺深度能激发肾俞穴不同的穴位疗效,因此,只有明辨肾俞穴穴性并辅予合适的刺灸方法、穴位配伍及针刺深度,才可更好地发挥肾俞穴的治疗效果。

基于德尔菲法的蒙药安神补心六味丸临床应用专家共识条目分析

目的:为蒙药安神补心六味丸(吉如和-6)的进一步临床推广应用和研究开发提供参考。方法:采用德尔菲法,查阅相关文献资料,经过小组讨论、半结构式访谈等形式初步确定了安神补心六味组方配伍与临床应用特点的专家共识相关问卷层次和条目池,采用线上函询和现场发放调查问卷2种方式向从事蒙医药临床、科研、教学及生产的专家进行咨询,对目前安神补心六味丸的组方配伍、临床应用特点等进行评价,直至基本达成一致,最终确定安神补心六味丸的组方配伍和临床应用专家共识条目。结果:2轮函询共有42位专家参与。根据文献调研、小组讨论及半结构式访谈,第1轮设置函询指标16个;之后根据专家意见修改指标体系,第2轮设置函询指标17个。经过两轮函询,最终在安神补心六味丸的组方配伍和临床应用2方面17个条目达成共识,涵盖了本方的组方配伍、用量、主治病和合病证、用药时辰等主要内容。结论:通过共识发现将野牦牛心替换为牛心的安神补心六味丸依然有良好疗效,临床使用风险较低。

基于BLT计算复杂腔体结构屏蔽效能的拓展方法

本文通过拓展BLT(Baum-Liu-Tesche)方法,计算了复杂结构腔体的屏蔽效能(Shielding Effectiveness,SE). BLT方法最初被用于分析传输线模型,后被拓展到计算腔体屏蔽效能,然而其局限于计算矩形腔体和圆柱腔体的屏蔽效能,无法分析更加复杂的腔体结构.本文将BLT方法与数值方法相结合,同时利用机器学习的回归方法,将其拓展到复杂腔体结构的屏蔽效能计算中.本文首先计算了腔体二维截面的特征模;然后,基于电磁波传播规律建立了等效电路网络结构,结合BLT方法获得腔体屏蔽效能的频域响应分布;最后,利用机器学习方法训练支持向量回归模型(Support Vector Regression,SVR),修正频域响应幅值,得到腔体目标的屏蔽效能.本文采用了3种不同结构的腔体对提出的方法进行了验证,频率范围为0.1~3 GHz.以商业软件仿真得到的结果为标准,本文提出的方法可以在85%的置信度条件下,实现均方根误差小于3,同时计算速度相比商业软件提升80倍以上.

款冬花药用历史的本草考证及沿革变迁

款冬花首载于《神农本草经》,历代本草专著和方书典籍中有关其药用历史的记载十分丰富,是临床中常用的止咳化痰药。目前,关于款冬花的基原、产地、规格等级等已有较多综述,但性味、功效记载的变迁,以及古代应用的考证及现代应用的评述未见相关综述。性味是中药药性理论的核心部分,反映中药性质、性能,是临症治法、遣药组方的重要依据。此外,历代典籍中记载了大量的款冬花方剂和应用,有值得深入挖掘的价值。

附子药理作用机制及减毒增效技术的研究进展

附子具有回阳救逆、补火助阳、温经散寒等功效,但对心脏、肝脏等多系统具有毒性作用,如何在保证疗效的同时降低毒性值得探究。目前,对附子的药理研究主要集中在其强心、保护血管、抗肿瘤、抗炎镇痛及保护神经系统等方面,并在不断挖掘新的方向,如调节免疫及改善糖尿病等。作用机制主要为通过多成分、多靶点、多途径地调控相关信号通路、离子通道等,在生物体内发生细胞水平、组织水平和系统水平的改善。对附子的减毒增效的研究主要是在炮制方法的革新和药物配伍的作用机制等方面。随着科技发展,无胆炮制、微生物发酵技术等逐渐推广应用,不仅能在降低附子毒性的同时维持甚至提升附子的药理作用,还研发出某些疾病的专属性炮制品,对附子的毒理及配伍后药物成分研究也有了长足发展。本文对附子近年来的药理作用及减毒增效的研究进展进行综述,并总结阐述了现有研究的不足之处,以期更好地利用附子资源。

配伍比例及炮制方法对川楝子-小茴香药对中9种成分含量的影响

目的考察不同配伍比例及炮制方法对川楝子-小茴香药对中芦丁、异槲皮素、阿魏酸、槲皮素、异川楝素、山柰酚、川楝素、α-蒎烯、反式茴香脑含量的影响,探讨其配伍使用的最优比例。方法分析采用HPLC-DAD法,ZORBAX SB C_(18)色谱柱(4.6 mm×250 mm,5μm);流动相乙腈-0.1%磷酸,梯度洗脱;柱温30℃;体积流量1.0 mL/min;DAD检测器。采用SPSS 24.0软件分析数据之间的差异性。结果9种成分在各自范围内线性关系良好(r≥0.9991),平均加样回收率96.19%~103.13%,RSD 1.86%~2.67%。川楝子-小茴香1∶1、1∶2、2∶1组中9种成分总含量高于川楝子+小茴香(1∶0+0∶1)组(P<0.05),川楝素-小茴香(1∶1)组总含量最高;炮制后,川楝素、异川楝素、α-蒎烯、反式茴香脑含量降低(P<0.05,P<0.01),异槲皮素含量升高(P<0.01),其余成分含量变化不明显。结论该方法准确度高,重复性好,川楝子与小茴香配伍后有利于9种成分总量的溶出,比例为1∶1时含量最高。

上跨铁路既有旧桥防撞护栏更换设计研究

随着公路、铁路行业规范及标准的不断更新,早期建造的公路上跨铁路桥防撞护栏已不满足现行交通环境下的防护需求,需要对其进行改造升级。根据现行规范及标准要求,上跨重要铁路的公路桥单层防撞护栏等级已提高至不小于HA级。为保证既有铁路的安全,必须选用耐久性较好的防护屏并在施工防撞护栏过程中考虑挂篮防护设计。因既有旧桥设计技术标准相比现有规范要求较低,在对公路上跨铁路桥防撞护栏进行更换设计时,考虑既有公路桥桥面板与防撞护栏适配性尤为重要。以天津市某上跨铁路既有旧桥防撞护栏更换设计为例,探讨现行规范实施后防撞护栏更换设计的计算方法及原则,为涉铁路外工程提供参考。

LD公路隧道开挖施工方案优化对比研究

LD改线公路隧道出口段,属于涉铁1km范围内,对隧道施工有严格要求,且天窗期严重影响施工进度,因此该施工段不宜采用爆破施工,现场采用徐工XTR6/280悬臂掘进机进行隧道开挖.调研国内外铣挖施工研究成果,并依托LD隧道铣挖法施工现场测试试验,得到适合LD隧道铣挖法施工的地质条件,并通过松动圈试验、初支结构受力试验以及数值分析对比相同地质下悬臂掘进机施工与爆破法施工对围岩扰动的影响.实验结果表明,当LD隧道的地质条件为岩石抗压强度小于40 MPa、岩体完整系数小于0.2、岩石质量指标RQD小于20%、岩体体积节理数大于30条/m^(3)、地下水不(弱)发育时,悬臂掘进机掘进速率高于爆破法施工,且悬臂掘进机施工对围岩的扰动远小于爆破法施工.引水隧道与LD改线公路隧道地质情况相似,可为引水隧洞涉铁部分及相似工程提供参考依据.