分数阶黏弹性模型在饱和软土与单桩相互作用中的应用

引入基于分数阶导数的Merchant模型,以描述饱和软土的黏弹性特征,并通过积分变换推导出变换域内的应力-应变关系;根据弹性-黏弹性对应原理,得到横观各向同性分数阶黏弹性饱和软土地基的解答,并将其作为地基边界元解的核函数;基于轴向受力的2节点桩单元的单元刚度矩阵,构建单桩的有限元解;将地基的边界元解和桩的有限元解进行耦合,以求解地基与单桩的相互作用问题;随后,设计算例验证本文理论的正确性,并对分数阶次对桩-土相互作用的影响进行分析。     

直角坐标系黏弹性层状地基荷载作用下的解析刚度矩阵解

基于直角坐标系下黏弹性力学的基本控制方程,通过Fourier-Laplace变换及矩阵理论,推导出三维空间问题和平面应变问题在积分变换域的解析解,进而得到相应问题的精确单元刚度矩阵;然后根据对号入座原则组装得到总体刚度矩阵;通过求解总体刚度矩阵形成的代数方程,得到层状地基相应问题在积分变换域内的解答;应用Fourier-Laplace逆变换技术,得到其物理域内的解。求解黏弹性问题退化的弹性问题并与已有解答进行比较,验证本文计算方法的正确性,并分析黏弹性地基黏滞系数对沉降的影响。研究结果表明:黏滞系数越大,土体的蠕变越明显,地基达到最终沉降的时间将越长。     

动载荷作用下无限长FGM梁在分数阶黏弹性地基上的精确解

基于分数阶微分Zener型黏弹性地基模型,建立动载荷作用下无限长FGM梁在分数阶黏弹性地基上的运动控制微分方程。利用傅里叶和拉普拉斯变换将控制微分方程简化为代数方程。首先在频率域内得到解答,然后利用傅里叶和拉普拉斯逆变换以及卷积定理将解答再转换回时间域内,得到黏弹性地基上FGM梁的挠度、速度、加速度、弯矩和剪力响应的精确解。最后,计算了冲击荷载作用下弹性地基FGM梁的动态响应,给出了x=0处梁的垂直速度和弯矩的响应曲线,其形状特征和均匀材料梁相同,且材料梯度指标p对结果的影响较小。     

弹性地基上夹紧圆板加热后的非线性轴对称自由振动

根据弹性地基上的加热圆板非线性轴对称自由振动的无量纲常微分控制方程,结合周边夹紧的边界条件,采用打靶法得到了数值解答.分析了不同无量纲地基刚度系数k对应的1阶热屈曲模态,给出了无量纲升温μ对应的前3阶无量纲自然频率,同时得出了不同无量纲地基刚度所对应的前3阶振动模态.     

桥台后路堤多级加载下黏弹性饱和成层软土地基一维固结分析

将桥台后路堤荷载简化为横截面梯形分布的半无限条形荷载,基于Boussinesq弹性力学解答推导得到桥台后软土地基内竖向附加应力计算公式,由此考虑初始孔隙水压力非均匀分布特性.结合桥台后路堤多级加载的Laplace变换递推公式,运用Laplace变换及其逆变换方法求解Terzaghi固结与Kelvin黏弹性应力应变联合微分方程,获得桥台后路堤多级加载条件下黏弹性饱和成层软土地基固结变形解答.算例分析结果表明:该解答具有合理性和可靠性,计算结果可为桥台后软土地基沉降分析提供参考.     

弹性地基上加热圆板的非线性轴对称自由振动

基于von Karman薄板理论和Hamilton原理,运用假设时间模态法,得到了弹性地基上加热圆板非线性轴对称自由振动的常微分控制方程.考虑不可移简支边界条件,采用打靶法得到了一阶屈曲位形下的前3阶振型的数值结果.结果表明:随地基弹性系数增加,热屈曲临界温度增加;在小振幅的情形下,振型对屈曲构型的影响和地基系数对振型...     

层状地基与弹性薄板相互作用的边界元解

将无限大薄板的基本解作为薄板边界积分方程的核函数,对薄板的内部和边界进行离散,并假定薄板内部和边界上的节点与地基反力的分布情况,得到薄板的边界元方程组;同时基于层状地基的解析层元解,通过Guass-Legendre积分得到地基柔度矩阵;结合地基与薄板接触面上的位移协调条件,得到层状地基与薄板共同作用问题总的边界元法方程组;求解该方程组,得到层状地基与薄板共同作用问题的解答.基于本文理论,编制了相应的FORTRAN程序,通过与已有文献结果对比验证本文理论及程序的正确性,数值分析结果表明:方形基础薄板情况下,离板中心越近,垂直于坐标轴y(x)方向、距离相等的2条线段的竖向位移差越小,且该位移差随着板-土刚度比减小而减小;随着板长宽比的增大,板中心点与长边中点位移差变化不明显,而短边中心与边界角点的位移差也有相类似的规律.     

软土地基基坑开挖对临近桩变形影响的时效分析

为解决软土地基基坑开挖条件下,邻近桩基水平位移随时间逐渐发展的问题,结合两阶段分析方法,第一阶段引入三维分数阶Merchant黏弹性模型来描述软土的蠕变特性,采用对应性原理和Laplace积分变换方法,求得附加应力的Mindlin时域解;第二阶段将桩基看作Pasternak地基上的Timoshenko梁,将所得附加应力加载在桩基上,建立桩基的变形微分方程,利用有限差分法对方程进行求解,得到考虑桩基剪切效应及桩土剪切层厚度的桩基水平位移时域解. 通过与已有文献中的算例进行对比,验证了该方法的正确性. 最后,对三维分数阶Merchant黏弹性模型参数（剪切模量、体积模量、黏滞系数、分数阶）进行了影响因素分析. 结果表明,所得方法能够较好地反映基坑开挖引起邻近桩基水平位移随时间的发展规律.     

动载荷作用下无限长FGM梁在分数阶粘弹性地基上的精确解

基于分数阶微分Zener型粘弹性地基模型,建立动载荷作用下无限长FGM梁在分数阶粘弹性地基上的运动控制微分方程。利用傅立叶和拉普拉斯变换将控制微分方程简化为代数方程,首先在频率域内得到解答,然后利用傅立叶和拉普拉斯逆变换以及卷积定理将解答再转换回时间域内,得到粘弹性地基上FGM梁的挠度、速度、加速度、弯矩和剪力响应的精确解。最后,计算了冲击荷载作用下弹性地基FGM梁的动态响应,给出了x =0处梁的垂直速度和弯矩的响应曲线,其形状特征和均匀材料梁相同,且材料梯度指标p对结果的影响较小。     

双参数弹性地基上矩形板的有限差分法

采用双参数弹性地基模型,通过弹性地基上矩形板网格划分,把网格结点的挠度微分方程化为差分方程.并引入边界条件,把地基板外的虚结点挠度用板上结点挠度表示,建立起包括各个结点挠度的差分方程组,编制相应的通用计算机程序,得到四边自由矩形板的解答.计算结果表明,该方法原理简单易懂,计算结果可靠,可在实际工程中运用.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has