含间隙平面机械系统KED分析

本文将运动副间隙视为无质量的刚体杆，提出了具有运动副间隙的平面机械系统运动弹性动力（KED）分析的有限元法．并以平面铰链四杆机构为计算实例，讨论了构件弹性及运动副间隙同时对系统动态特性的影响．     

Grashof定理的重要推广

在提出并证明了关于铰链四杆闭链中转动副之整转性的若干引理、定理的基础上,给出了系统、完备的铰链四杆机构类型判定定理,对传统、著名的Grashof定理作了重要的延伸和推广。     

平面四杆机构的动力学概率分析

在平面连杆机构运动学概率分析的基础上,建立了平面连杆机构动力学参数的概率分析模型,给出了平面四杆机构运动副反力的概率数字特征值计算公式,并以一简单平面铰链四杆机构介绍了此模型的使用.整个模型以矩阵形式表达,避开了对机构输出表达式直接微分时复杂的数学运算,成功地解决了机构输出参数误差的相关性问题.     

平面边杆机构的防卡可靠性

本文考虑了平面边杆机构中运动副轴线的偏移和歪斜对机构的影响。并进行了由此而引起的机械防上住问题的可靠性分析。最后以铰链四杆机构为例，阐述了该分析方法的应用情况。     

平面连杆机构的防卡可靠性

本文考虑了平面连杆机构中运动副轴线的偏移和歪斜对机构的影响。并进行了由此而引起的机构防卡住问题的可靠性分析。最后以铰链四杆机构为例，阐述了该分析方法的应用情况。     

平面运动链中驱动机构的识别

一个机构由于选择不同的铰作为驱动副而得到的驱动机构可能不同．为此，对驱动副位置的可能性进行了研究，定义广义平面运动链、相容铰、平面运动链的同位杆、平面运动链的同位铰、以及机构的同位铰等新概念，最后提出一种识别平面运动链中驱动机构的有效方法．     

连杆平面通过五个位置的运动综合

采用两组四位置设计问题相结合的方法解决五位置的运动综合问题，把自由曲线自动求交的原理应用于圆心（圆点）曲线，改进了连杆平面精确通过五个指定位置时设计铰链四杆机构的方法，避免了直接求解时不易收敛的问题     

平面铰链四杆机构的运动几何学模型

以微分几何学为基础，提出了平面铰链四杆机构的运动几何学模型．对于众多类型的平面四杆机构的运动几何学问题，只需求解最简单的基本机构的位移方程；然后通过角度参量变换模式，便可求得运动几何学参数，为其应用及动态仿真软件的编制提供了理论依据．     

平面综合铰链四杆机构运动分析及其优化设计

将刚体的平面运动分析用于平面综合铰链四杆机构的运动分析中,讨论了已知连杆上一点的起始位置、连架杆的对应转角及机架长度等,平面四杆机构的解析解,并对其进行了优化设计。     

确定平面机构自由度的新方法──逐次设定连架杆法

由机构具有确定运动的条件出发，分析了运动副对构件轨迹的约束情况，得出机构具有确定相对运动的必要条件：（１）在运动过程中相连接两构件运动副处的轨迹应相同；（２）相连接两构件上的点的相对运动要满足运动副对构件的约束条件，提出了逐次设定连架杆法，以不满足必要条件前所设定的连架杆数来确定机构的自由度数。其特点是可以不考虑机构是否存在局部自由度、复合铰链、虚约束和公共约束，就能确定机构的自由度。     

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.     

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