StephensonⅢ型六杆间歇机构近似函数综合自适应方法

提出了平面机构连杆曲线局部自适应拟合方法,定义了连杆曲线具有三次鞍点意义的局部自适应圆、局部自适应直线,把六杆间歇机构近似函数综合转化为平面曲线局部自适应拟合问题,建立了StephensonⅢ型六杆间歇机构近似函数综合的数学模型,给出了可同时保证输出函数间歇与非间歇部分精度要求的优化求解方法,算例表明该优化过程是可行的.     

四杆机构九精确点轨迹综合的延拓法

平面四杆机构连杆上某点精确通过预定九个点位的轨迹综合问题是长期以来难以精确求解的课题，至今，多以近似求解法求解．本文将以求解多项式方程组的延拓法求解基于标准型方程而导出的高次多项式方程组，详细介绍了延拓法及其计算机算法，该方法的特点是能可靠地得到方程给的全部数学解系，但计算量大，本文最后给出了九精确点轨迹综合实例及其计算结果，经计算机动画模拟演示，说明计算结果是正确的．     

四杆机构九精确点轨迹综合的延拓法

平面四杆机构连杆上某点精确通过预定九个点位的轨迹综合问题是长期以来难以精确求解的课题，至今，多以近似求解法求解，本文将以求解多项式方程组的延拓法求解基于标准型方程而导出的高次多项式方程组，详细介绍了延拓法及其计算机算法，该方法的特点是能可靠地得到方程给的全总部数学解系，但计算量大，本文最后给出了九精确占轨迹综合实例及其计算结果，经计算机动画模拟演示，说明计算结果是正确的。     

基于解域分析的直线机构综合方法研究

对给定机架、直线点位置及方向的机构综合条件,提出了一种铰链四杆直线机构的综合方法,所得到的直线在给定点为四个无限接近点的近似直线.传统的机构综合方法无法得到给定条件的全部解,因此很难得到性能最优的机构.首先确定机构解域,将满足要求的无穷多机构解直观地表示在有限坐标平面内,设计者可以直观准确地得到平面内机构的各种属性,因此能在全部机构中选到最优的机构,解决了选取机构的盲目性问题,从而大大缩短了设计周期.     

平面四杆机构轨迹综合的延拓法

本文采用一种全新的非线性方程组求解方法—“延拓法”对平面四杆机构轨迹精确点综合问题进行了深入的研究，首先简要阐述了延拓法，以复数法和标准双失组建立了四杆机构五精确点轨迹综合方程，导出了延拓法可解的多项式方程组，详细论述了方程组的求解过程并给出了实例及其部分计算结果．     

带有移动副的平面单输入-双杆组连杆机构回路自动识别方法

将具有j个环路的平面单输入-双杆组连杆机构看作由具有j-1个环路的子机构与一个双杆组组成,则此机构的回路情况由组成它的子机构的回路情况、双杆组的构形以及双杆组与子机构运动的相互作用决定.基于此思想,在全面分析了所有类型双杆组的构形及装配条件的基础上,与型转化法机构结构分解路线的自动生成相结合,实现了平面SIDM回路识别的系统化与自动化;为计算机辅助机构综合提供了理论基础和技术方法.     

结合连续法与数值图谱法的刚体导引尺度综合

由连续法得到满足刚体导引综合要求的齿轮四杆机构，利用该机构连架杆摆角函数的谐波成分(由快速傅立叶变换得到)，通过模糊识别的方法，从已建立的齿轮四杆机构的连架杆摆角函数谐波特征参数的“数值图谱库”中找到更多组满足设计要求的机构。文中给出的算例验证表明，该方法解决了有限点位连杆机构尺度综合的多解问题，为连杆机构的尺度综合研究拓宽了思路。     

平面机构综合

本文以平面杆组的“型转化”理论为基础,并加以发展。将复杂机构的分析与综合问题置于一个统一的流程模式之下。其中包括机构的运动综合、轨迹综合和多功能的具有速度、加速度要求的运动综合及动力综合等问题。这一流程模式的函数过程仅是单构件与双杆组的“基本函数”过程的积木式搭配。与此相应建立了适用于数值计算的分析方法和综合方法。文中附有机构分析与综合的若干实例。     

函数逼近理论与平面连杆机构近似综合问题的关系

针对运动几何学对平面连杆机构近似综合的不足，介绍了函数逼近理论与平面连杆机构近似综合问题的关系，为解析法进行平面四杆机构综合提供了简便的方法。     

Stephenson型机构及其诱导机构的曲柄存在条件

本文采用文献[1]提出的平面杆机构的三角形划分的方法,探讨了Stephenson型机构及其诱导机构的曲柄存在充要条件。 1 Stephenson型机构的曲柄存在充要条件 按照主动杆的不同,Stephenson型机构可划分为图1(a),(b)两种形式。     

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