Observation of spin Coulomb drag in a two-dimensional electron gas

An electron propagating through a solid carries spin angular momentum in addition to its mass and charge. Of late there has been considerable interest in developing electronic devices based on the transport of spin that offer potential advantages in dissipation, size and speed over charge-based devices. However, these advantages bring with them additional complexity. Because each electron carries a single, fixed value (- e) of charge, the electrical current carried by a gas of electrons is simply proportional to its total momentum. A fundamental consequence is that the charge current is not affected by interactions that conserve total momentum, notably collisions among the electrons themselves. In contrast, the electron's spin along a given spatial direction can take on two values, +/- [planck]/2 (conventionally upward arrow, downward arrow), so that the spin current and momentum need not be proportional. Although the transport of spin polarization is not protected by momentum conservation, it has been widely assumed that, like the charge current, spin current is unaffected by electron-electron (e-e) interactions. Here we demonstrate experimentally not only that this assumption is invalid, but also that over a broad range of temperature and electron density, the flow of spin polarization in a two-dimensional gas of electrons is controlled by the rate of e-e collisions.     

翼型远场、中场阻力计算方法对比研究

本文研究应用了远场阻力计算方法,以及基于翼型阻力分解策略的中场积分计算阻力的方法。远场阻力计算方法是利用动量定理推导得出的,该方法较传统的表面积分方法,具有不受物体表面的影响,对于复杂外形也适用的特点;中场积分方法是近年来提出的一种新的计算阻力的方法,该方法将流场分为三个不同的区域：波阻区、型阻区、数值耗散区,通过对不同区域进行积分将阻力分解为波阻、型阻、数值耗散阻力。计算结果表明中场积分方法与传统的表面积分方法和远场积分方法相比,不仅可以将阻力分解成不同部分以便于进一步分析阻力产生机理,而且在计算中对网格量的要求较低,即使在网格量较小的情况下也能得到较精确的结果。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

测量游泳动态阻力的附加阻力微扰动法

为使运动员在训练和比赛中有良好技术表现,对游泳推进力和动态阻力的测量进行了研究。提出了一种利用微小附加阻力的方法,用于在泳池中测量游泳运动员游进时的动态阻力。实验中测量运动员在附加小阻力前后的游进速度,并记录附加阻力值,代入到在推进力不变假设条件下导出的阻力计算公式,即可得到动态阻力值。应用设计的装置实测了一些运动员在自由泳和蛙泳时的动态阻力和阻力系数。结果表明,不同泳姿下水对人体的阻碍作用不同,阻力系数可作为泳姿的评价参数。该结果可为指导训练和分析运动员技术动作提供参考。     

库仑定律与毕奥-萨伐尔定律

应用狭义相对论研讨电磁场基本定律,由库仑定律和洛伦兹变换推导出毕奥—萨伐尔定律。依据两相对匀速直线运动的惯性参考系,以两惯性参考系之间力的洛伦兹变换为基础,分析两点电荷之间的相互作用力,导出洛伦兹力公式,定义磁感应强度,最后推导出毕奥一萨伐尔定律。     

光诱致聚乙炔激子的产生和演化

在Su—Schrieffer—Heeger（SSH）哈密顿基础上引进弱电子关联,对反式聚乙炔链中单激子的产生和演化过程实施了分子动力学模拟．结果表明,弱关联的引入显著加快了激子的产生和演化,激子形成的时间由零关联的104fs缩短为48fs;弱关联未能使呼吸子的振荡周期发生显著改变,但呼吸子振荡成为等振幅恒频率模式．聚乙炔光诱致吸收试验中的瞬时高频吸收峰解释为呼吸子吸收．     

能量载体与理想的燃烧组织方式

分析了燃烧现象中能量载体的构成，提出了反应能量载体和附加能量载 体的概念，研究了反应能量载体和附加能量载体对燃烧现象的影响。综合考虑燃料与助燃剂、能量传递和燃烧产物排放过程，提出了理想的燃烧组织方式。     

二维非极性晶体中的声学激子

本文研究二维非极性晶体中通过形变势与声学声子强耦合激子的性质,采用线性组合算了表拉格朗日乘子法,导出了强耦合情形下非极性晶体中表面激子的有效哈密顿量,得到符和面激子的重正化质量。     

Photoluminescence and Exciton Energy Transfer of A Novel Perylene-Containing Polyimide

1 Introduction Peryleneimides are well known chromophores combining high quantum yields of photoluminescence with outstanding photochemical and thermal stability. Due to their useful electroactive and photoactive properties many potential applications in optoelectronics have attracted increasing interest.1IntroductionPerylenei mides are well known chromophores combining high quantumyields of photoluminescence withoutstanding photochemical and thermal stability. Due to their useful electroacti…     

颗粒物质中的微扰

介绍了容器中颗粒物质内部受到局域微绕的研究进展,并对微扰态的性质和规律做一些分析和讨论。     

闪锌矿InGaN耦合量子点中的激子态

在有效质量近似下,用变分法研究了受限于闪锌矿InGaN耦合量子点中的激子态.数值结果显示了量子点的结构参数和铟含量对闪锌矿InGaN耦合量子点中的激子态有明显的影响.激子结合能随着垒层厚度的增加有个最小值,而随着点高和半径的增加单调地降低.     

库仑摩擦最速降曲线问题的讨论

库仑摩擦轨道上的最速降线问题是一个受到众多研究者关注的问题。根据变分法及其变量变换不变性的性质,得到了轨道切线方向与菇轴的夹角及其对时间的导数构造可能极值函数能够满足的端点条件,以经典的无摩擦的最速降问题作了验证。据此,求得了库仑摩擦最速降线的解析表达式,分析归纳了库仑摩擦最速降轨迹斜率的匀变性、尺度的相似性、轨迹函数依摩擦系数的分簇性和运动的临界性等基本性质。     

变分法研究半导体量子线中激子束缚能

本文运用变分法,推到了柱形量子线中的激子束缚能随量子线半径变化关系,同时计算了量子线中激子的波函数和变分参数。推导中分别采用了无限势阱模型和有限势阱模型进行计算。     

有向设计和完备的错位纠正码

介绍了基于有向设计编制完备错位纠正码的若干方法，包括一些存在性结果。