静载荷作用下扁球壳轴对称非线性自由振动

研究了扁球壳在静载荷作用下的轴对称非线性自由振动问题。根据扁球壳非线性动力变分方程，运用修正迭代法给出非线性静力边值问题的一次近似解析解，应用Ｇａｌｅｒｋｉｎ技术得到了关于时间部分的非线性动力方程，用Ｌｉｎｄｓｔｅｄｔ－ｐｏｉｎｃａｒé摄动法获得了以静载荷为参数的非线性固有频率与振幅间的特征关系，并以图表的形给出算例．本文的退化结果，可直接得到圆薄板轴对称非线性自由振动的有关结论．     

圆柱型正交各向异性圆板的后屈曲分析

选取与正交各向异性参数ｋ￣２有关的简单多项式作为挠度试函数，基于Ｖｏｎ－Ｋáｍá型大挠度方程组，采用Ｇａｌｅｒｋｉｎ技术对周边转动弹性约束圆柱型正交各向异性圆板的后屈曲问题进行了分析．特例给出与各向同性圆板完全吻合的结果．计算结果表明，所选试函数具有收敛快、精度高等优点，尤其在约束较“弱”的情况下（即文中γ＿ｓ≤１．０），其结果比文献［１］用Ｌｅｇｅｎｄｒｅ多项式为试函数的结果精度高得多．     

圆薄板在复合载荷作用下的非线性振动问题

采用摄动变分法，取圆薄板的中心最大振幅为摄动参数，对在复合载荷作用下的圆薄板的非线性振动问题进行了研究，一次近似得到了圆薄板的线性固有频率，二次近似得到了静变形状态下的非线性固有频率．     

弹性圆薄板在随动力作用下的屈曲问题分析

取弹性圆薄板内一微元体,建立了圆板在非保守载荷——切向均布随动力作用下的轴对称非线性控制方程,考虑周边固支和周边不可移简支两种边界条件,采用打靶法和解析延拓法求解了所得两点边值问题,获得了圆薄板特征值问题的数值解,结果可供工程设计时参考使用．     

高阶剪切理论下梯度直梁在热环境中的静动态响应分析

基于高阶剪切变形梁理论研究了两端不可移简支功能梯度梁在横向非均匀升温下的热屈曲和自由振动问题。首先依据高阶剪切变形梁理论和Hamilton原理建立了功能梯度梁受热-机载荷共同作用下的几何非线性动力学控制方程;在研究静态热屈曲问题时,把方程退化成强非线性边值问题,采用打靶法数值求解该边值问题,获得了横向非均匀升温下梁的屈曲构型,绘出了梁的变形随温度载荷及材料梯度参数变化的特征关系曲线;研究动态响应时,采用Navier方法数值求解所建立的动力学控制方程,获得了横向非均匀升温下梁的自由振动响应,数值比较了不同剪切理论下梁的前3解固有频率随跨高比、材料梯度参数变化的规律。结果表明,剪切变形、梁的跨高比、材料的非均匀性、温度变化对于高阶剪切功能梯度材料梁的变形及固有频率有很显著的影响。     

薄环板与扁薄锥壳组合结构在横向载荷作用下的非线性振动

从弹性壳体的无量纲控制方程出发,研究了一类薄环板与扁薄锥壳组合结构在横向均布载荷和温度载荷作用下的大挠度非线性振动问题.采用打靶法对周边固定的问题进行了数值求解,分析和讨论了组合结构的固有频率与外载荷、锥底和环板半径比例、扁壳锥度的非线性关系以及结构刚度的变化.     

热环境下弹性地基上多孔FGM圆板的自由振动特性

基于一阶剪切变形理论，研究了热环境下弹性地基上多孔功能梯度材料（Functionally Graded Materials，FGM）圆板的自由振动特性.首先，考虑含孔隙的Voigt修正混合幂律模型，并给出统一温度场描述材料受温度依赖，利用Hamilton原理，推导热环境下弹性地基上多孔FGM圆板自由振动的控制微分方程并进行无量纲化；然后，应用微分变换法对无量纲控制微分方程和边界条件进行变换，得到计算无量纲固有频率和临界温升值的代数特征方程.将问题退化后并与已有文献结果进行对比以验证其有效性；最后，计算并分析了梯度指数、孔隙率、边界条件、厚度与半径比、温升值和Winkler 弹性刚度系数对多孔FGM圆板无量纲固有频率的影响以及各相关参数对临界温升值的影响.结果表明，梯度指数影响频率，反映材料从陶瓷向金属过渡的特点，孔隙率削弱刚度进而影响固有频率大小，Winkler地基对刚度有着增强的作用，温度增大使结构发生热屈曲而失稳等.     

复合材料圆柱壳非线性热弹耦合振动

根据复合材料圆柱壳热状态下的非线性动力方程，研究了复合材料圆柱壳的非线性热耦合振动，应用Ｇａｌｅｒｋｉｎ原理及改进的Ｌ－Ｐ法对其非线性热耦合振动进行求解，并讨论了分析了温度、长径比、厚径比对复合材料圆柱 非线性热振动固有频率的影响。     

圆板在周边面内载荷作用下的非线性振动

本文采用摄动变分法讨论了边界横向夹紧、中面内有均布载荷作用的圆形薄板的非线性自由振动问题。求出了与面内载荷有关的圆板的近似线性和非线性固有频率,并给出了不同载荷参数下的特征曲线。结果表明,线性问题的临界压力是保守的,而当压力超出临界压力一定范围时,圆板的非线性固有频率仍有意义。     

变形对夹层圆板非线性振动影响及其周期解

为了解决载荷作用下夹层圆板非线性振动的大挠度方程求解问题,采用基于空间模态假设和变分法,导出时间模态的控制方程.采用伽辽金法推导出静挠度和动挠度耦合作用下夹层圆板的非线性动力方程,从而求解出解的时间模态的渐进表达式.最后采用Lindestedt-Poincare摄动法求解中心点附近的周期解并绘制出幅频特性曲线.结果表明:当横向激扰使夹层圆板产生较大幅度的受迫振动的同时,由于载荷作用下变形的存在,其产生的附加动挠度就会与变形产生非线性耦合现象,因而由此产生的变形必将影响夹层圆板的动力学特性.该成果对非线性振动问题的研究具有一定的参考价值和指导意义.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

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

正~~