有限元混合法求解几种特殊弹性接触问题时的处理方法

用弹性接触有限元混合法求解弹性接触问题时，对有些特殊的接触情况会导致有限元方程组病态，从而使接触求解失败。对此作了分析讨论，找出了接触求解失败的原因，并提出了相应的处理方法。该法根据接触情况，适当修正相应的病态矩阵，从而使特殊的接触问题有解。     

基于力信息的机器人接触状态下作业的技能学习

为实现机器人接触状态下作业的演示编程，使机器人获得人的基于力信息的作业技能，首先提出了描述接触状态的元素接触形式，用元素接触形式序列建立技能模型，根据不同的接触形式具有的不同腕力分布，利用支持向量机(SVM)对不同的元素接触形式进行辨识，在此基础上机器人获得人在接触状态下的作业技能，实现了演示编程方法中最关键的一步。     

机车车辆轮轨接触问题的数值模拟

按照机车、车辆车轮与标准轨道的实际几何关系建立了三维有限元模型，并采用有限元参数二次规划法求解轮轨弹塑性接触问题．通过弹塑性接触计算，得到了大量的轮轨接触力、接触状态和轮轨应力的数据，根据计算结果分析比较了机车轮轨接触和车辆轮轨接触的区别，对轮缘贴靠钢轨形成两点接触时的接触情况进行了初步分析.     

群桩沉降验算中接触单元模型应用的若干问题

分析了群桩沉降验算中接触单元具体应用的一些问题，包括单元剖分中接触单元的选取与设置范围，对刚性桩和柔性桩接触单元的应用作了分析比较，并建议了接触单元的弹塑性模型．     

大变位下多体系统摩擦接触问题线性规划求解方法

建立了多体系统中摩擦接触问题的整体控制方程，在大变位情况下将其分解成两个线性互补问题，一般通过两次线性规划求解可完成一次接触问题的求解，大大地减少了接触问题求解的迭代次数和计算量，并且可直接得到系统中接触界面上的接触应力，从而克服了对于多体系统求解接触问题需要多次迭代和难于直接得到接触应力的缺陷．数值算例表明了该方法的合理性和有效性，为大变位下多体系统中接触问题的求解提供了有效的手段．     

接管弯矩作用下补强圈与容器壳体间的接触特性

采用非线性有限元模拟了壳体和补强圈的接触行为，通过对接触行为的控制来改善收敛；考察了接触变形和接触压力，指出接触的发生具有局部性；提出一种“试算法”来确定刚度因子，同时对补强圈与容器间的间隙变化对接触的影响也做了探讨。     

弹性流体动力润滑状态下线接触滚动副表面层的应力及接触疲劳寿命

线接触滚动副早期失效主要是由于接触表面的润滑不良．使得表面粗糙度波峰相 互接触而产生磨损及表面破坏．但在润滑良好的情况下，由于接触表面压力分布的变化．在某些 工况参数下．接触副的疲劳寿命出现降低现象．本文通过数值方法，对ｎ种典型工况参数下接触 副表面层的应力分布进行计算，分析了接触副的疲劳寿命，提出了弹性流体动力润滑应用中合理 选择工况参数的必要性．     

考虑微凸体侧接触的结合面法向接触刚度建模

提出了一种考虑微凸体侧接触影响的结合面法向刚度建模方法。通过采样获取接触表面轮廓数据后，用统计方法研究了接触表面上微凸体之间的水平距离分布，发现微凸体之间的水平距离分布近似呈正态分布。基于微凸体侧接触理论和微凸体连续变形理论，建立微凸体的法向接触刚度模型后，根据微凸体水平距离的分布规律，利用统计理论，构建了结合面法向接触刚度模型。分析结果表明：在两个接触表面平均间距相同时，提出模型的法向接触载荷大于KE模型，小于高志强(GZQ)模型；在间距较小时，提出模型接触刚度小于KE(Kogut L和Etsion I)模型接触刚度，在间距较大时，提出模型接触刚度大于KE模型接触刚度，并且提出模型的法向接触刚度总是小于GZQ模型接触刚度；基于提出模型的有限元分析获得的前三阶模态与试验结果一致，固有频率与试验结果最大相差8.2%,说明提出的模型能够比较准确地预测结合面的法向动态特性。     

机械结构中的接触热阻

论述了接触热阻在机械工程和机床研究中的应用；接接触突峰宰化为圆锥接触模型，经出了计算单点接触热阻的新公式；在分析机械加工表面微形状和接触变形的基础上，推出了计算多点接触热阻的理论算法；对所提出的算法进行了实验验证。     

基于Morris法滑动磨损与接触疲劳耦合损伤寿命分析

针对线接触滑动磨损与接触疲劳耦合损伤荷载摩擦副系统，结合改进Archard磨损模型、临界平面法和虚拟裂纹扩展法，建立了一种滑动磨损与接触疲劳耦合损伤分析模型.基于Morris灵敏度分析方法，提出了耦合损伤接触疲劳灵敏度贡献比，建立了一种基于灵敏度贡献比滑动磨损与接触疲劳耦合损伤寿命预测方法.结果表明：耦合损伤寿命明显小于单一损伤寿命；接触压力、接触宽度和曲率半径对耦合灵敏度具有显著影响，接触疲劳损伤贡献比与显著影响参数基本呈线性关系；耦合损伤寿命预测结果与计算结果基本一致，验证了耦合寿命预测模型的可用性.     

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

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