结构动力响应的精细时程积分并行算法

大型结构动力响应问题采用传统的时间步长直接积分方法求解是非常耗时的,因此发展相应的并行计算方法成为必然．传统的直接积分方法是极度串行而不适于并行计算,而精细时程积分方法可以使用大步长单步计算出求解区间任意时间点的响应值,为并行计算提供了极大的可能性．结构动力响应方程通过变量变换可以转化为一阶线性常微分方程,该方程组的解由表示初值影响的齐次方程解和反映荷载作用的积分之和组成．其中第一项用矩阵指数函数计算;第二项在文中采用精细时程积分傅里叶展开方法计算（设计了３种相应的并行算法）,并在ＴＲＡＮＳＰＵＴＥＲ并行机上实现．结果表明,３种ＨＰＤ－Ｆ并行算法有很高的加速比和并行效率．     

区间精细算法与长效精细算法的对比研究

如何应用精细算法求解非齐次或非线性问题是计算力学中的热点问题，通常采用区间精细算法，但这一方法的精细传递矩阵与t步长的区间有关，计算量很大．能否设计出“一次计算，终生使用”的长效精细算法是一个倍受关注的问题，尤其是针对非线性的情况．以Burgers方程为模型设计出一种能解决二次非线性困难的长效精细算法．这类技巧不难推广至一般的二次非线性PDE（偏微分方程），且有广泛的应用，还建立了相应算法的基础理论与误差分杯两个算例表明，计算结果十分令人满意．     

非线性动力学方程的自适应精细积分

将定常结构动力方程的精细积分算法推广应用于非线性动力学问题的求解．对非线性项的线性化处理使该方法的计算精度对时间步长非常敏感,为此将龙贝格积分法引入该方法,提出了由此而产生的指数矩阵的快速精细算法,从而使时间步长的选择具有了自适应性,计算精度和效率均得到提高。     

求解变系数奇异摄动问题的精细积分法

将高阶乘法摄动法与子区段消元法结合,提出一种求解一端有边界层的变系数奇异摄动2点边值问题的精细积分方法.首先用一个不大的步长将求解区域均匀离散,然后采用高阶乘法摄动方法求解出每个子区段内的传递矩阵.由状态参量在相邻节点间的精细积分关系式确定一组代数方程,该方程可通过递推消元法高效求解.由于每个子区段内的传递矩阵为一系列指数矩阵之积,可利用精细积分法精确计算,因此该方法具有很高的精度和效率.数值算例证明了方法的有效性.     

流-固耦合问题的精细积分求解法

为了解决流-固耦合动力学求解效率和精度低等问题,提出了增维精细积分法.根据有限元理论推导流-固耦合方程,将流-固耦合方程改写成状态空间形式,在矩阵仅增加1维的情况下将积分运算转化为代数运算,扩大了精细积分法的应用范围,从而得到增维矩阵的流-固耦合精细积分求解.同时,将增维精细积分法与Newmark法的计算结果进行对比,以验证其有效性.结果表明,由于不用求解矩阵H的逆矩阵,增维精细积分法避免了矩阵奇异带来的计算解的不稳定性.增维精细积分法与Newmark法的计算结果较吻合,且其在较大计算时间步长条件下的计算精度较高.     

车桥耦合系统动力响应的精细时分析

为了研究车桥耦合系统的动力响应,本文首先将普通精细时程积分法进行改,即将车辆荷载和车辆惯性力以“渐进”的方式加载到整个系统上。然后通过数值实例,编写MATLABT通用计算程序求解,得到运用改进时程法在积分步长较大情况下能得到较精确的结果,最后对计算精度和计算时间进行研究,得到积分步长对计算时间影响较大,积分间隔对计算精度的影响较大,所以在使用改进的精细积分计算式一般选取较大的积分步长和较小的积分间隔。     

车桥耦合系统动力响应的精细时程分析

为了研究车桥耦合系统的动力响应,首先将普通精细时程积分法进行改进;即将车辆荷载和车辆惯性力以"渐进"的方式加载到整个系统上。然后通过数值实例,编写MATLABT通用计算程序求解,得到运用改进时程法在积分步长较大情况下能得到较精确的结果。最后对计算精度和计算时间进行研究,得到积分步长对计算时间影响较大,积分间隔对计算精度的影响较大,所以在使用改进的精细积分计算式一般选取较大的积分步长和较小的积分间隔。     

非线性偏微分方程组的数值解在化学工程中的应用

以求解Ｎ－甲基二乙醇胺水溶液对Ｈ２Ｓ和ＣＯ２同时吸收的传质动力学模型为例，讨论了求解非线性偏微分方程组的问题．以一阶泰勒展开式来逼近方程中的非线性项，通过反复迭代即可使方程最终得以求解．计算结果表明，这种方法有较好的稳定性．     

新型曲面四边形边界元精细后处理方法研究

为了精确计算三维静电场的电场强度和电位分布,提出了新型曲面四边形边界元方法．在该方法中,对模型边界面进行二阶四边形单元剖分,对二阶单元顶点上的节点号重新编号,以单元的顶点为求解点,根据二阶四边形曲面参数方程,结合面积比值法定义的曲面单元顶点的形状函数,计算曲面单元顶点的函数值．与一阶平面四边形边界元相比,新型曲面边界元法在没有增加计算节点的情况下,由于采用更接近实际边界的曲面积分,计算精度将明显提高．但由于边界面采用二阶单元粗略剖分,单元数量相对较少,剖分后的模型较粗糙．虽然顶点节点上的函数值比较精确,但只能以平面线性单元的形式显示,离实际模型边界差别较大．本文就此提出边界元精细后处理方法．在该方法中,对曲面单元两边按一定步长等分,再根据曲面的参数方程把曲面单元精细显示出来．单元上新建节点的函数值可由曲面单元顶点上的函数值和面积比值法定义的形状函数插值得到．最后形成经精细显示后的新型曲面边界元方法．算例表明,经精细显示后边界面比未处理前更接近实际边界．     

类硼六重态离子NⅢ,OⅣ跃迁波长的GRASP2计算

采用相对论多组态Ｄｉｒａｃ－Ｆｏｃｋ方法计算ＮⅢ，ＯⅣ１ｓ２ｓ２ｐ３６Ｓ０——１ｓ２ｐ３ｐ６Ｐ跃迁精细，其波长值与Ｊ．Ｈ．Ｂｌａｎｋ和Ｂ．Ｆｒｉｃｋｅ（ＰｈｙｓＳｃｒｉｐｔａ，１９９２，４５：４３０）计算值和实验值（跃迁波长）进行了比较，并讨论了组态相关．     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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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