磁场调制下液晶指向矢偏转特性的研究

液晶具有独特的物理化学特性,体现电、磁各向异性,且光学上类似单轴晶体。当对液晶体系施加磁场,液晶指向矢将随着磁场的大小而发生偏转。利用液晶连续体弹性理论模型,研究了沿面排列的向列相液晶分子在外磁场作用下的光学调制效应,通过差分法数值模拟液晶分子指向矢的偏转特性,并对液晶磁致双折射效应进行了分析研究,为更好地研究液晶型偏振光调制器提供理论基础。     

电场对向列相液晶指向矢取向的影响

讨论了静电场对正介电各向异性的向列相液晶指向矢取向的影响。计算了典型向列相液晶的指向矢偏转角随场强和位置的变化。结果表明,当电场低于阈值电场ＥＣ时指向矢取向不发生偏转,当电场超过ＥＣ时指向矢取向在转变层ξ内与电场方向有较大偏转,而在ξ外几乎沿电场方向,电场越强,偏转角越大。指向矢偏转角、ＥＣ和ξ还与液晶材料各向异性、弹性常数、温度及液晶层厚度等有关     

向列液晶的偶极关联因子

给出了计算向列相液晶偶极关联因子的方法，对PAA进行了具体的数值计算。结果表明偶极关联因子与液晶的序参数、分子偶极矩沿分子长短轴分量以及分子的具体结构等有关。     

德国科学家研制液晶分子泵

据英《新科学家》２００１年３月２４日报道：德国莱比锡大学的科学家 Ｗａｌｔｅｒ Ｌｅｈｍａｎｎ最近声言，一种类似橡胶的聚合物分子骨架制造的脉动液晶分子摆可以用来制造分子泵。液晶分子可以在电场中旋转用以阻挡光线，因此被广泛用于制造各种显示器。但由于液晶分子是自由漂浮的，一旦想推动液晶分子，它们就会游走，故用它们很难制作有用的机械。为了让液晶也能用于制造机械零件，Ｌｅｈｍａｎｎ就把液晶分子连接到一种称为聚硅氧烷的类似橡胶的链形聚合物上，结果就形成一种像梳子的齿似的向下悬挂的新材料。由于液晶的棒状分子和…     

OCB模式液晶显示器件响应时间研究

文中在讨论响应时间对液晶显示的重要意义的基础上,从分子外场运动微分方程入手解析了响应时间的影响因素,重点研究了光学补偿弯曲模式(OCB)液晶盒的快速响应原理.从引流与分子外场下运动相互作用入手,结合流速梯度变化描述了指向矢动态衍生过程,并从能量角度讨论液晶盒最佳驱动波形.最后基于成核中心对快速响应的贡献给出一种新型初态...     

向列型液晶的界面效应强度

本文讨论了向列型液晶扭曲盒在外加磁场的作用下，基板的易取向轴与液晶指向矢的倾角与界面结合强度和磁场强度的关系。     

用液晶(Liquid crystals)膜实现微波可见性的图形显示

<正> 胆甾相液晶(cholesteric liquid crystals)中的分子分层排列。在每层中的分子排列取向一致。但在层与层之间排列方法向扭转了一定角度,因此多层分子链的排列方向逐层扭转,而呈螺旋结构。当分子的排列方向旋转360°,又回到原来取向时为一个周期。在一个周期中,分子链排列完全相同的两层中间的距离称为螺距。当液晶受热而温度升高时,     

分子中含—CH2O—桥键液晶化合物的结构和相变间关系

合成出一组分子中含－ＣＨ２Ｏ－桥键的４－（ｔｒａｎｓ－４－ｎ－烷基环己基甲氧基）－４’－氰基联苯液晶化合物，经ＤＳＣ了其相变温度范围，研究发现液晶分子中的吸电子端基有助于化合物呈现液晶相及增加液晶相的热稳定性；随分子锘链长的增另，有助于液晶呈现近晶相但液晶相的热稳定性降低；分子中环己烷环的存在增强了液晶相的热稳定性。     

液晶的磁旋光特性

为深入了解液晶的磁旋光特性，利用矩阵方法分析研究了液晶的旋光效应，导出了液晶旋光的矩阵表示．通过测量磁场作用下向列型液晶的旋光角及透射比，研究了液晶的磁旋光特性．详细分析了磁场对液晶分子轴旋转和透射比的影响，做出了液晶分子轴旋转角和透射比与磁场强度关系的曲线．通过改变磁场方向进行实验测试．发现液晶的旋光方向与垂直入射液晶盒的磁场方向无关。     

电场和磁场对液晶分子取向的影响

该叙述液晶相与它的分子结构，液晶的各向异性，电光效应和液晶应用及电场和磁场对液晶分子取向的影响，并围绕这个问题进行讨论。     

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     

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     

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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