求解堤坝渗流场的罚函数无单元法

从变分原理出发,采用罚函数法处理渗流边界条件,推导了用无单元法求解有自由面的堤坝渗流问题的基本方程和迭代格式,给出了罚因子选取的具体表达式,并计算分析了某不透水地基上土坝的稳定渗流场.与电模拟试验成果的比较表明,文中所提出的计算方法和程序是正确的,且应用罚函数无单元法求解堤坝渗流问题,可以得到较高的计算精度和计算效率.     

一类可微的精确罚函数方法

针对通常精确罚函数方法在可行域边界不可微的缺点,构造了一类可微的精确罚函数方法,使得它能采用无约束优化方法中许多有效的解析方法。作者提出了精确罚函数的构造,讨论了它的性质,证明了算法的收敛性,并给出了数值计算实例。     

Lagrange乘子初始值和罚因子迭代方式的研究

本文以Rockafellar乘子罚函数作为基准,利用Matlab强大的数值计算功能,通过数值试验,对Lagrange乘子初始值和罚因子迭代方式进行了研究,比较了不同的乘子初始值和罚因子迭代序列对算法效率的影响,为大规模优化算法的研究提供了有益的借鉴.     

封闭壳体内旋转圆盘附近流场的研究

运用罚函数有限元方法计算了间隙流场内速度的分布,并计算了在小间隙比时光滑旋转圆盘上的粘性力矩．通过实验,测量了封闭壳体内旋转圆盘上的粘性力矩．实验数据与计算结果相符．     

螺栓法兰连接的数值模拟及接触收敛分析

螺栓法兰连接的数值模拟过程中涉及许多接触对,在处理接触问题时,收敛困难这一问题普遍存在.以使用ANSYS Workbench对齿轮压缩机法兰连接的有限元分析为例,详细分析了影响计算收敛性的主要因素:接触对的建立、接触类型和接触算法的选取,以及罚刚度大小.在模拟过程中,用非对称绑定接触模拟螺母与螺栓的连接,非对称摩擦接触模拟螺母与法兰,以及法兰之间的连接,线性施加预紧力的方式来模拟螺栓拧紧.在数值计算过程中,绑定接触采用罚函数法,摩擦接触采用增广拉格朗日乘子法.初次计算采用一个较小的罚刚度系数,然后根据计算过程中接触迭代计算和N-R残差检查情况,逐步增大罚刚度系数直至得到收敛的计算结果.计算结果收敛性好,接触面摩擦应力分布符合压应力分布规律且仅有少量的滑移,满足工程使用要求.为其他类型接触问题的分析过程中解决收敛困难的问题提供了参考.     

用乘子罚函数和海森矩阵计算最佳潮流

本文提出一种实用的方法以求解最佳潮流问题。用固定罚因子的乘子罚函数化有约束问题为无约束问题,然后用海森矩阵求解无约束最优化问题。用文章提出的方法对5节点,11节点系统以及IEEE30节点试验系统作了试验。计算的结果与某些其他方法的结果进行了比较。     

非线性不等式约束优化问题的指数型精确罚函数算法

针对非线性不等式约束优化问题,通过增加一个变量构造了一种新的指数型罚函数,进而证明了该罚函数的光滑性和精确性.进一步,设计了一种求解非线性不等式约束优化问题的精确罚函数算法.数值计算的结果表明了该算法的可行性.     

非线性混合整数规划的罚函数法

本文主要对非线性混合整数规划问题的求解进行讨论.首先介绍传统的l1精确罚函数及其性质,但由于l1精确罚函数的不光滑性,用l1精确罚函数求解时还必须将其连续化.为了计算简单,我们通过构造一个光滑的精确罚函数,它可以直接将非线性混合整数规划问题化为一个无约束的规划问题,然后给出了一个全局解等价的充要条件,从而可通过求解无约束的规划问题而得到原问题的解.     

非线性优化问题的光滑化序列二次规划方法

为了获得序列二次规划方法的全局收敛性,通常需要借助一个罚函数,但常用的罚函数由于具有不可微性从而给计算带来一定的困难,拉格朗日函数虽然可以克服此困难,但其形式较为复杂,为解决该问题,给出了一类光滑化罚函数.基于一类双曲余弦型光滑化罚函数,提出了等式约束优化问题的一个光滑化序列二次规划方法.该光滑化函数具有良好的连续、可微性和凸性质,在适当条件下,获得了算法的全局收敛性,并给出数值测试说明了算法的有效性.     

对于外罚函数与模式搜索相结合的最优化算法中惩罚项的讨论

在文[1]中发表了用罚函数外点法与模式搜索相结合的最优化算法和程序。本文对于其中的惩罚项进行了分析探讨,并且给出了计算实例。计算证明其损失函数如改成二次型式则效果显著提高。     

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