推力轴承的边界元分析

目前边界元法还很少用润滑问题的研究，原因在于雷诺方程的基本解很难求得。本通拟合推力轴承的油膜厚度，将雷诺方程转化为拉普拉斯方程的形式，用边界元法很快就得到了推力轴承的压力分布，计算结果表明，该方法的计算精度在实际工程中是能够被接受的。     

流体润滑问题的边界元分析

本文把流体润滑中的压力控制方程的形式转化为泊松方程,采用边界元法求解压力分布,从而有效地降低了代数方程组的阶数,能够大幅度减少计算机机时并使结果的精度提高。文中对螺旋槽推力轴承和扇形瓦推力轴承进行了分析,获得了满意的结果。所研制的计算程序可方便地用于各种几何结构的动压、动静压问题的分析,特别是对复杂的几何区域或对同一轴承进行大量计算时更为方便。     

计入三维热效应对可倾瓦推力轴承动力特性的影响

在考虑三维热效应的情况下,研究线支撑可倾瓦推力轴承的动力特性.建立广义雷诺方程、完整的三维能量方程、瓦体的热传导方程和温粘关系,联立求解非线性偏微分方程组,计算油膜的刚度和阻尼系数.研究表明：温度变化对可倾瓦推力轴承的动力特性有较大影响;与不计入热效应的线支撑可倾瓦推力轴承相比,计入三维热流体的可倾瓦推力轴承的油膜刚度和阻尼系数会增大,其理论计算结果更接近实际工况;随着载荷、入口温度的增加以及转速的减小,油膜的刚度和阻尼也会随之增大.     

水轮发电机推力轴承的广义热弹性流体动力润滑性能分析

本文以二维雷诺方程、能量方程、三维热传导和三维热弹位移边界积分方程为基础,用边界元法求解油膜压力、瓦体温度场和瓦面热弹位移,编制了一个较完善的热弹性流体动力分析软件.利用这一软件,计算了托盘支承双层水冷可倾瓦轴承的热弹性流体动力性能,研究了载荷、转速、隔热层或热阻、水冷瓦、油池温度和托盘变形等因素对轴承性能的影响.结果指出,重载时轴瓦的热弹变形将导致工作条件恶化,接触热阻或隔热层对于改善瓦的变形是有利的,水冷瓦可以降低瓦温并改善瓦的变形,油池温度对各项性能有较大影响,托盘变形的影响很小.     

推力滑动轴承结构参数的数值研究

以推力轴承扇形瓦块为研究对象,采用柱面坐标,通过对二维雷诺方程进行离散化求解,得出推力滑动轴承的无量纲压力分布,并通过数值计算研究方法,详细研究了瓦高比、长宽比和瓦块数对轴承润滑性能的影响规律,指出了推力滑动轴承最佳结构参数的确定方法,为推力滑动轴承的结构设计提供了理论支撑。     

重载径向轴承润滑力学问题数值解

本文应用八节点等参元法直接离散了二阶雷诺方程,并以“双重均值法”代替传统的方法,求解了计入弹性变形和粘压关系在内的非线性方程组.成功地得到了考虑轴颈偏斜的重载轴承中截面偏心率ε=1.0015,端面偏心率ε_3=1.045时的各种静特性参数.本文还总结出一个最小油膜厚度计算公式.为重载径向轴承的润滑力学计算提供了一个收敛速度快,,适用范围广的数值计算方法.     

考虑表面粗糙效应的液体动压推力轴承的求解

讨论了考虑表面粗糙效应的推力轴承求解方法，建立随机形式的雷诺方程，分析一维精糙度对轴承性能的影响，所得结论对这类轴承的设计有一定的指导意义。     

基于有限元的塑料瓦推力轴承油膜特性分析

应用COMSOL Multiphysics对塑料瓦推力轴承建立有限元三维模型,在塑料瓦表面求解雷诺方程,得到塑料瓦表面的压力分布,以确定其弹性变形量,用于塑料瓦推力轴承油膜的特性分析.分析结果表明,载荷增大时油膜压力明显增大,并且油膜压力最大值向推力瓦出油区一侧移动,在推力瓦上产生较大变形;转速增加有利于形成流体动压润...     

润滑剂的流变特性和表面粗糙度对动压滑动轴承承载能力的影响

运用光滑表面轴承的近似解析雷诺方程作为粗糙表面轴承的理论分析基础,导出粗糙表面非牛顿流体润滑的雷诺方程,并将它们用来分析阶梯形滑动轴承的设计问题.其计算结果与具有相同名义油膜厚度的光滑表面轴承进行比较表明,润滑剂的流变性能和表面粗糙度对于轴承的承载能力和工作表面的摩擦力有很大影响.     

边界积分方程中近边界点几乎奇异积分的计算

该文针对边界元法存在近边界点力学量计算的困难,给出了一个通用性方法,将近边界点到边界单元的距离参数通过分部积分变换到积分式之外,从而计算出二维问题近边界点参量的几乎强奇异和超奇异积分.该法同样适用于板壳问题的边界元法,尤其是对于将超奇异边界积分方程正则化为强奇异边界积分方程的边界元法,求解近边界点参量更加有效.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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