用有限体积法计算叶轮机械内三维粘性流动

用数值计算方法研究离心叶轮内流场的三维粘性流动.在流场计算中,利用有限体积法对三维N-S方程组进行差分离散,并应用SIMPLER算法来求解.在流场计算的基础上,应用速度矢量图等后处理方法来显示和研究湍流的存在与发展.并将数值模拟的结果与实验数据进行对比和分析.两者相符表明了该数值模拟的有效性.     

颗粒材料崩塌模拟与特征研究

颗粒材料所表现出的行为特征是许多工艺技术及自然现象研究的理论基础.为对颗粒材料的崩塌特征进行深入研究，应用离散单元数值方法对颗粒材料崩塌进行了数值模拟，计算通过了试验数据的数值验证，说明计算结果是正确而有效的.在数值计算模拟的基础上，对两类典型颗粒崩塌过程及特征进行了研究与分析，最后利用数值计算结果得到不同崩塌条件下静止核心区的规律曲线并进行了分析.     

钝体结构倒U形梁气动特性试验和数值研究

为了探索有效的钝体结构气动特性三维数值分析方法,对钝体结构倒U形梁的气动特性进行了风洞试验和数值模拟研究.通过风洞试验得到与结构气动特性相关的气动力系数和颤振导数.利用二维或三维模型分别对结构的气动特性进行了数值模拟研究,并计算了相关的气动参数.计算过程中基于分块迭代耦合方法考虑流体-固体耦合效应,利用自编程序结合CFX软件实现不同物理场间的数据交换和传递,采用快速有效的网格移动控制算法处理移动边界问题.风洞试验测量和数值计算中均考虑了湍流效应,其中数值计算应用了k-ω剪切应力输运模型和分离涡模型.通过风洞试验测量与数值模拟研究可以发现,钝体结构倒U形梁的气动稳定性较差.对气动参数的计算结果表明,本文的三维数值计算方法可以有效地获取钝体结构的气动参数,在风工程领域具有重要应用价值.     

理论分析和数值计算在霍尔效应实验中的应用

阐述了理论分析和数值计算在霍尔效应实验中的应用.对螺线管轴线磁场大小进行了推导和计算,利用ANSYS软件对螺线管轴向磁场分布进行了数值计算,对理论计算值、模拟计算值和实验测量值进行了比较,找到了实验测量值有较大误差的原因.将理论分析和数值计算法引入传统物理实验中,开拓了物理实验教学的新模式,加强了学生对物理知识的理解,提高了学生应用三大方法解决实际问题的能力.     

MATLAB与C#混合编程在ASP.NET数值计算中的分析与实现

在面向科学研究与工程计算领域的ASP.NET程序开发中,常需要加入数值计算功能,针对编写数学函数工作量大、效率低、可靠性差等问题,提出应用MATLAB与C#混合编程的解决办法.文章简单介绍了MATLAB与C#在数值计算和界面开发方面的优缺点,分析了实现两者混合编程的必要性及其基本原理与数据交互.以海洋仪器SBE911 CTD综合测量系统温度传感器的系数校准为例,详细说明了将MATLAB与C#混合编程应用在ASP.NET数值计算中的一般方法与步骤.实际应用表明,这种方法具有可靠性好、编程简单、实用性强等特点.     

螺管式电磁铁吸力特性的数值分析

各种类型的电磁铁吸力特性的计算是电磁铁设计计算中的主要内容.本文分析讨论了基于法拉第——麦克斯韦观点的多种电磁力计算公式,结合数值计算的特点与要求,提出了较为理想的电磁吸力数值计算方法. 本文应用有限元法,在求得电磁铁内磁场分布数值解的基础上,按文中提出的电磁吸力计算方法,获得了吸力特性的数值解,计算结果由实验予以验证. 从螺管式电磁铁吸力特性这一典型的数值分析结果出发,可将该法进一步推广应用于各种型式的交、直流电磁铁吸力特性的数值分析,在此基础上有可能构成电磁铁的计算机辅助设计的新方法.     

斜流式喷水推进器内部三维紊流流动的数值模拟与性能分析

应用数值模拟方法研究斜流式喷水推进器内部紊流流场,基于紊流流场计算分析了其特性.采用三维贴体坐标网格对计算区域进行剖分离散,选择k-ε双方程紊流模型,应用SIMPLEC数值方法计算内流场各流动参数,进而根据流场的计算结果预测了该推进器内部泵在不同工况下的性能.计算结果与实验结果进行了对比,二者有较好的一致性.     

ANSYS有限元分析系统在数值传热中的应用

针对ANSYS有限元软件分析系统在数值传热方面的应用进行了简介,并对实际的传热实例进行了数值计算分析.     

抛物型微分方程的多尺度有限元高效计算

提出了抛物型微分方程的高效多尺度数值计算方法.与传统有限元基函数相比,多尺度有限元基函数能更好地反映问题自身的强振荡微观信息,结合多尺度有限元格式,可使计算结果在宏观尺度获得很好的数值逼近.对时间采用欧拉向后差分离散化,得到稳定且收敛的数值结果.新方法在取得高仿真逼近的同时,节约了大量计算资源和时间,因而更具应用价值.     

网格技术在中尺度数值天气预报MM5模式中的应用

以中尺度数值天气预报MM5在网格环境下运行为例,分析了基于网格计算的应用系统在资源共享方面的应用.介绍了中尺度数值预报模式的差分近似算法,并以基于网格计算的中尺度数值天气预报MM5为例,给出了在网格环境下的实验流程和结果.实验表明.使用Globus技术使得原本只能在集群或小型机上运行的科学计算程序能够在普通PC上运行起来,并且随着加入网格机器的增多,可以提高运行速度和吞吐量.     

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