液饱和多孔介质中Rayleigh型波的传播

研究了由多孔固体骨架和无粘流体构成的多孔介质的瑞利型表面波的传播 ,获得了联系着复波数对频率的依赖关系的弥散方程 ,结果表明 :其表面波是弥散和非均匀的 ,表面波沿多孔介质表面衰减 ,同时其振幅远离介质表面呈指数衰减     

固体颗粒在逾渗多孔介质中的吸附特性

采用数值计算的方法,通过求解描述低速流体流动的Stokes方程以及简化的颗粒运动方程,初步得到颗粒在逾渗多孔介质中的运动轨迹,并在此基础上,求得颗粒与多孔介质内表面的碰撞概率,进而研究颗粒的被吸附特性.数值结果表明均匀多孔介质和分形多孔介质对颗粒的吸附存在本质差异.颗粒流出概率(实际中常表示为出口悬浮液中的颗粒浓度)与多孔床深度间的指数关系仅对均匀多孔介质成立,而对分形多孔介质并不成立.     

两类典型非牛顿驱油剂的渗流特性

为考察不同流变性质的驱油剂在油藏中的渗流规律,基于孔喉作为实际油藏多孔介质最基本的流通单元和孔隙尺度随机分布的特点,提出了多孔介质的微观简化模型--二维随机变截面微管束.采用数值方法研究了粘弹型驱油剂和幂律型驱油剂在单个孔喉和多孔介质微观简化模型中的流动特性.结果表明,对于粘弹型驱油剂,只有当注入强度达到一定值时,粘弹效应才能明显地体现出来,渗流阻力随粘弹性的增强而增加,随孔隙尺度和非均匀程度的减小而增加.对于幂律型驱油剂,其渗流阻力随流体非牛顿性的增强而降低,随孔隙尺度和非均匀程度的变化规律与粘弹型驱油剂大体一致,但是在数值上远小于后者.对比分析驱油剂在岩心中的渗流规律发现,二维随机变截面微管束可作为多孔介质的简化模型,以此作为研究驱油剂渗流机理的基础模型可以避免岩心试验中多因素的综合作用,体现单一因素如流变性、孔隙介质结构和非均质性对驱油剂渗流特性的影响.     

混合介质低频介电增强效应的等效电容模型

针对油气开采时岩石等混合介质在低频段出现的介电增强现象影响测井数据准确性的问题,提出一种混合介质低频介电增强效应的等效电容(CMEC)模型。首先根据储油层岩石电参数特性建立层状含膜介质模型,并将其等效为集总电路形式进行介电谱分析;同时给出3层含膜介质的电势分布,由此分析膜层电导率及膜层厚度对介电增强特性的影响。分析结果表明:等效介电常数在低频段的增强是电容模型有效厚度在低频段减小引起的,而其增强幅度和薄膜参数之间存在着定量关系;由于CMEC模型计算含膜介质介电谱时引入的模型参数相对较少,运算量约为有限差分算法等数值模拟方法的10%。该模型可为油田地质结构的低频介电测量提供准确依据。     

两类典型非牛顿驱油剂的渗流特性

为考察不同流变性质的驱油剂在油藏中的渗流规律,基于孔喉作为实际油藏多孔介质最基本的流通单元和孔隙尺度随机分布的特点,提出了多孔介质的微观简化模型--二维随机变截面微管束.采用数值方法研究了粘弹型驱油剂和幂律型驱油剂在单个孔喉和多孔介质微观简化模型中的流动特性.结果表明,对于粘弹型驱油剂,只有当注入强度达到一定值时,粘弹效应才能明显地体现出来,渗流阻力随粘弹性的增强而增加,随孔隙尺度和非均匀程度的减小而增加.对于幂律型驱油剂,其渗流阻力随流体非牛顿性的增强而降低,随孔隙尺度和非均匀程度的变化规律与粘弹型驱油剂大体一致,但是在数值上远小于后者.对比分析驱油剂在岩心中的渗流规律发现,二维随机变截面微管束可作为多孔介质的简化模型,以此作为研究驱油剂渗流机理的基础模型可以避免岩心试验中多因素的综合作用,体现单一因素如流变性、孔隙介质结构和非均质性对驱油剂渗流特性的影响.     

层状饱和多孔介质中弹性波场的数值模拟

基于Biot介质理论,对层状饱和多孔介质中弹性波的传播进行数值模拟.通过双相饱和多孔介质的一阶双曲型速度-应力弹性波波场分离方程,采用交错网格高阶有限差分法实现P-S波在层状饱和介质中的高精度数值模拟,并利用完全匹配层(PML)吸收边界来处理边界反射问题,取得较好的效果.模拟实例表明,该方法具有很好的稳定性和较高的精度,能够成功地将非均匀介质中的P波波场和S波波场从混合波场中分离出来,但由于饱和多孔介质中快纵波和慢纵波相互伴生,此方法无法实现两类纵波的分离.     

粘塑性流体在分层介质中的流动规律

分析了地下流体矿藏在开采过程中渗流流动复杂性机理，介绍了粘塑性流体剪切应力与速度梯度之间的非线性关系，在此基础上，分析了在均匀介质和分层均匀介质中的渗流流动规律，并定性研究了粘塑流体在非均匀介质中的流动特性。     

基于流阻率的吸声材料声学性能研究

运用加权残值法建立了两种介质相互作用的声学有限元计算方程式. 基于多孔纤维材料等效流体的经验公式,分析了复声速和复密度相对流阻率的变化规律. 针对不同多孔吸声材料结构布置形式,采用上述有限元计算方程和经验公式,计算得到随流阻率变化的传递损失. 结果表明,空气滤清器型结构传递损失随流阻率增加而增加;阻性消声器型结构传递损失随流阻率而变化的规律复杂,在计算频段内存在峰值.     

非均匀饱和土层的波动响应分析

采用基于混合物理论的多孔介质模型,建立饱和土介质一维动态响应问题的控制方程,在基本方程中考虑土体的非均匀性以及变形过程中的固体颗粒相和孔隙流体相体积分数的变化.选取固体骨架位移、孔隙流体位移以及孔隙流体压力作为状态变量,利用Laplace积分变换建立问题的状态方程.作为数值算例,考虑饱和土层的物理力学性质沿深度方向按指数函数连续变化,利用打靶法和数值Laplace逆变换获得在阶跃荷载作用下的位移和应力场物理量的瞬态响应,重点分析讨论材料非均匀性对饱和土介质动力特性的影响.结果表明,非均匀性对饱和土的瞬态响应有显著的影响;在小变形假设下组分相的体积分数变化很小.     

非均匀分布孔洞材料的梯度本构关系

提出了一种对非均匀分布孔洞材料的分层等效方法,宏观上可等效为材料参数随厚度变化的梯度材料．利用有限元方法建立代表单元体(RVU)的三维多层模型,并施加必要的边界条件,计算出各层的平均应力应变,将上述值代入多孔橡胶的本构方程(该方程由所选多孔橡胶的应变能函数推导),即可计算出描述等效梯度材料宏观力学性能的等效弹性参数,从而确定了非均匀分布孔洞材料的梯度本构关系,分析了2种典型的非均匀分布孔洞,从中可看出分布类型的影响．     

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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