Electron states scattering off line edges on the surface of topological insulator

We study the local density of states （LDOS） for electrons scattering off the line edge of an atomic step defect on the surface of a three-dimensional （3D） topological insulator （TI） and the line edge of a finite 3D TI, where the front surface and side surface meet with different Fermi velocities, respectively. By using a S-function potential to model the edges, we find that the bound states existed along the step line edge significantly contribute to the LDOS near the edge, but do not modify the exponential behavior away from it. In addition, the power-law decaying behavior for LDOS oscillation away from the step is understood from the spin rotation for surface states scattering off the step defect with magnitude depending on the strength of the potential. Furthermore, the electron refraction and total reflection analogous to optics occurred at the line edge where two surfaces meet with different Fermi velocities, which leads to the LDOS decaying behavior in the greater Fermi velocity side similar to that for a step line edge. However, in the smaller velocity side the LDOS shows a different decaying behavior as x-1/2, and the wavevector of LDOS oscillation is no longer equal to the diameter of the constant energy contour of surface band, but is sensitively dependent on the ratio of the two Fermi velocities. These effects may be verified by STM measurement with high precision.     

双热源复合换热器复合换热温差影响因素分析

空气-水双热源复合换热器是太阳能-空气双热源复合热泵系统的核心部件,空气-水双热源复合换热器的有效复合换热温差对空气-水双热源复合换热器的换热性能以及太阳能-空气双热源复合热泵的系统性能具有重要影响。建立了空气-水双热源复合换热器和太阳能-空气双热源复合热泵系统的数学模型,利用数学模拟的方法研究了空气-水双热源复合换热器结构参数,即内外管径、翅片间距对有效复合换热温差的影响。模拟结果表明:空气-水双热源复合换热器的有效复合换热温差随内管管径的减小、外管管径的增大以及翅片间距的减小而增大。     

高校图书馆电子阅览室的管理与建设

在电子阅览室的建设过程中,要统筹兼顾,克服硬件、软件在技术和资金方面的不足,努力拓展服务内容,建立一支高素质的馆员队伍。由于管理内容及形式与传统阅览室相比有明显不同,因而电子阅览室管理上也要有不同的要求。     

浅谈混凝土配合比设计中值得注意的几个问题

对混凝土配合比设计中值得注意的几个问题进行分析,并提出相应的防治措施。     

普通高校排球专项课的创新与发展

随着素质教育的深入开展以及排球竞赛规则的不断变化，普通高校排球专项课越来越不适应当前教育的需要，我们要更新理念，跟上排球发展的最新趋势，使排球运动在高校得到普及。     

Banach空间中三元非线性广义集值变分包含问题

文章提出并研究了Banach空间中的一类三元非线性广义集值变分包含问题:θ∈(w,x,y) A(z,u).利用集值m-增生映射的预解算子方法建立了该问题与不动点问题的等价性,并通过Nadler定理和构造辅助序列建立了解的迭代算法,由此证明了该问题解的存在性以及算法的全局强收敛性.文中所讨论的变分包含问题是许多已有问题的推广.     

电动汽车热泵空调系统低温供热实验研究

针对电动汽车热泵空调系统低温供热时性能衰减及融霜效率低的问题,设计了适应于低温供热的热泵空调系统循环,对影响系统性能的各因素进行了实验研究。该系统匹配良好,能适应热泵系统在低温环境下供热。采用合理的控制方法调节系统,能为电动汽车提供良好的乘坐环境。     

无界区域问题的高阶近似人工边界条件

研究泊松方程外区域问题的高阶近似人工边界条件，并给出了利用此人工边界条件时有限元逼近的误差估计式。     

无反射势阱的Schr?dinger方程的精确解

将无反射势阱的Schr?dinger方程作自变量双曲函数变换,可使其转化为associated-Legendre方程。从而得到分别用associated-Legendre多项式和函数表示的束缚态和散射态本征函数,并讨论了散射态的归一化和这种精确本征函数的应用问题。本文给出的解较文献中已有的渐近解或特殊值的解具有一般性。 关键词：     

Dynamical Transport Property through an Interacting Quantum Wire

Using the equation of motion, we investigate theoretically the dynamical ac conductance of a clean Luttingerliquid quantum wire adiabatically coupled to Fermi liquid electron reservoirs in the presence of short-ranged electron-electron interactions. For a perfect single mode quantum wire, in the limit of zero-ranged interaction we conclude that the static dc conductance of ω → 0 is e^2 /h, which is independent of the electron interactions. While in the dynamical case of ω≠0, the ac conductance oscillates with the amplitude e^2/h and the period which depends on the interaction strength and the driving frequency as well as the position in the wire.