运动阻尼对沟道辐射的影响

用正弦平方势描写了粒子－晶体相互作用，在运动方程中首次引入了阻尼项，讨论了运动阻尼对沟道辐射的影响。结果表明，运动阻尼不改变最大辐射频率，但明显地影响了辐射强度。     

正弦平方势与小振幅近似下的沟道辐射

引入正弦平方势,将面沟道粒子的运动方程化为无阻尼、无受迫的Duffing方程,并用Jacobian椭圆函数和椭圆积分解析地给出了系统的解和粒子运动周期,讨论了正电子面沟道辐射谱的一般特征,指出了利用沟道辐射作为激光的可能性.     

参数X-射线辐射在弯晶中的稳定性分析

由于晶体弯曲,系统可能变得不稳定,从而对粒子的沟道效应、沟道辐射以及相关的参数X-射线辐射的稳定性产生影响.在经典力学框架内和偶极近似下,引入正弦平方势,把粒子在弯晶中的运动方程化为具有常数力矩的摆方程.利用系统Hamiltonian分析了它的稳定性.结果表明,系统的稳定性与弯晶曲率Q有关,当条件0≤Q＜1满足时,系统...     

相对论粒子在晶格中相关散射

本文采用与粒子运动纵向分量相同的坐标系来考察相对论粒子同晶格原子相关碰撞及其量子辐射。通过相对论变换,使三维运动问题转化为两维问题(轴向沟道运动)或一维问题(面沟道运动),从而大大简化了计算步骤,并以几种典型的相互作用势,讨论了沟道轻粒子在晶格中运动时束缚态之间的跃迁。用Moliere势计算出MeV电子在晶格轴向沟道中运动时发射与韧致辐射不同的量子辐射谱的特征,与实验结果相当符合。     

面沟道离子的半波长和阻止本领

带电粒子在单晶面沟道中,由于受到面沟道势的作用,呈现周期性的振荡运动.随着粒子逐步深入晶体,粒子周期性地接近晶格平面,这时各种近距相互作用几率增强.如果测量背散射粒子能谱,就能在表面附近看到许多产额增强引起的小峰(精细结构),每一小峰对应于粒子每次接近品格平面,而两小峰之间的能量差△E对应于粒子振荡运动的半波长λ/2,有下列关系式; △E=λ/2[S_γ(K~2E)cosθ_(in)/cosθ_(out)+K~2γ(E)S_γ(E)]其中θ_(in)是入射束相对于样品表面法线的入射角;θ_(out)是背散射粒子相对于样品表面法线的出射角(探测器所置角度);K~2是运动学散射因子;E是入射粒子能量;S_γ(E)是随机方向的阻止本领;γ(E)是能量为E的面沟道粒子阻止本领与随机方向入射粒子阻止     

高交联型PDMS乳胶粒子合成工艺研究

采用乳液聚合方法合成了高交联型聚二甲基硅氧烷(PDMS)乳胶粒子。实验考察了超声时间对预乳化液稳定性和平均粒径的影响,分析了复合乳化剂中十二烷基磺酸钠(SDS)用量对PDMS乳胶粒子粒径及其分布的影响,讨论了甲基三乙氧基硅烷(MTES,交联剂)用量对PDMS乳胶粒子凝胶含量的影响。结果表明:超声时间超过20 min后,预乳化液稳定性开始变好,超过50 min后,平均粒径不再变化;SDS用量越大,PDMS乳胶粒子尺寸越小、分布越窄;MTES用量越高,PDMS乳胶粒子凝胶含量越大,超过2.5 g后,不再变化。     

北京市紫外辐射对人体健康的影响及其统计预报模型

利用2005-2011年中国科学院大气物理研究所铁塔分部的辐射观测资料和北京3所三级甲等医院2008-2011年皮肤病及眼部疾病急诊人数资料,对紫外辐射和相关疾病进行分析.选取与紫外辐射相关系数通过α=0.05显著性检验的气象要素作为预报因子,利用逐步回归方法分月建立紫外辐射强度预报方程.结果表明:紫外辐射与皮肤病的相关系数为0.367,与眼部疾病的相关系数为0.265,均通过α=0.001的显著性检验.不同月份紫外辐射的日变化规律不同,对人体产生伤害的时间段有所差异;紫外辐射强度与总云量、低云量、能见度、风向、风速、气压、相对湿度、气温等有关,其中与总云量、低云量、能见度的相关性最显著;1-11月预报方程历史回代检验的平均评分为82.8,试预报的平均评分为82.7;预报模型的拟合能力和推广能力较好,为实际业务提供了指导意义.     

超晶格"锯齿形"势垒的穿透系数

指出了沿生长方向的超晶格沟道不再是直的,而是"锯齿形"形的,对于n层等厚薄膜组成的超晶格,每一个锯齿都可视为一个等腰三角形,而"锯齿形"沟道则由n/2个三角形串联而成.于是"锯齿形"势垒的穿透问题就转化为三角形势垒的穿透问题.假设一个三角形势垒的穿透系数为γ,则n/2个三角形势垒的穿透系数可近似表示为γn/2=γn/2.结果为粒子与物质相互作用研究提供了一种理论描述.     

杂质粒子对二维尘埃等离子体系统相变的影响

利用分子动力学模拟研究了杂质粒子对二维尘埃等离子体系统的影响.分别计算了平均平方位移,两体相关函数来分析系统的机构特性.结果表明,在参数范围内,杂质的含量以及杂质的质量和电荷的大小都会减慢系统的相变.杂质粒子在质量和电荷上都小于背景的尘埃粒子.     

具有弱周期调制的形变超晶格退道效应

把超晶格“折沟道”对粒子的作用等效为形状相似的弱周期调制。利用正弦平方势把粒子运动方程化为具有外周期弱调制的非线性微分方程，导出了退道系数与晶格形变的关系。利用多尺度法研究了系统的主共振和子共振。     

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     

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