Holographic correspondence in topological superconductors

We analytically derive a compatible family of effective field theories that uniquely describe topological superconductors in 3D, their 2D boundary and their 1D defect lines. We start by deriving the topological field theory of a 3D topological superconductor in class DIII, which is consistent with its symmetries. Then we identify the effective theory of a 2D topological superconductor in class D living on the gapped boundary of the 3D system. By employing the holographic correspondence we derive the effective chiral conformal field theory that describes the gapless modes living on the defect lines or effective boundary of the class D topological superconductor. We demonstrate that the chiral central charge is given in terms of the 3D winding number of the bulk which by its turn is equal to the Chern number of its gapped boundary.     

蛋白质分子三维结构能量优化途径的选择

NMR方法是研究溶液中蛋白质的三维结构的重要手段,本文以BUSH ⅡA为例,对用度量矩阵距离几何法获得的初始三维结构进行了能量优化,主要探讨了蛋白质分子三维结构能量优化途径的选择问题.本文把优化过程分为三个阶段,分别采用不同的优化方式,使分子结构得到优化,对于分子量在8000左右的蛋白质而言,本方法能够获得较好符合核磁实验约束条件的分子低能构象.     

Zeta Function on a Generalised Cone

The analytic properties of the -function for a Laplace operator on a generalised cone are studied in some detail using Cheeger's approach and explicit expressions are given. In the compact case, the -function of the Laplace operator turns out to be singular at the origin. As a result, strictly speaking, the -function regularisation does not regularise and a further subtraction is required for the related one-loop effective potential.     

BV Structure of the Cohomology of Nilpotent Subalgebras and the Geometry of(W) Strings

Given a simple, simply laced, complex Lie algebra corresponding to the Lie group G, let be thesubalgebra generated by the positive roots. In this Letter we construct aBV algebra whose underlying graded commutative algebra is given by the cohomology, with respect to , of the algebra of regular functions on G with values in . We conjecture that describes the algebra of allphysical (i.e., BRST invariant) operators of the noncritical string. The conjecture is verified in the two explicitly known cases, ₂ (the Virasoro string) and ₃ (the string).     

The influence of surface geometry and topography on the fatigue cracking behaviour of laser hybrid welded eccentric fillet joints

Laser hybrid welding of an eccentric fillet joint causes a complex geometry for fatigue load by 4-point bending. The weld surface geometry and topography were measured and studied in order to understand the crack initiation mechanisms. The crack initiation location and the crack propagation path were studied and compared to Finite Element stress analysis, taking into account the surface macro- and micro-geometry. It can be explained why the root and the upper weld toe are uncritical for cracking. The cracks that initiate from the weld bead show higher fatigue strength than the samples failing at the lower weld toe, as can be explained by a critical radius for the toe below which surface ripples instead determine the main stress raiser location for cracking. The location of maximum surface stress is related to a combination of throat depth, toe radius and sharp surface ripples along which the cracks preferably propagate.     

基于磁偶极子构造法几何建模的铁管磁异常正演

地下铁磁性金属管线受地球原磁场磁化产生磁场会改变原地磁场分布,而形成地磁异常;通过管道几何建模和磁偶极子构造法对管道磁异常进行正演分析;首先利用近似的立方体单元对管道进行几何建模并输出相应的立方体单元体积和中心坐标;然后将立方体单元近似为磁偶极子,使用磁偶极子构造法进行管道磁异常正演;最后研究了距径比,磁倾角,磁偏角,地球场强,管道材料磁化率对管道磁异常正演的影响;研究结果表明:在6倍距径比外,同一球面上测点磁异常值接近一致, 且管道磁异常正演结果不受磁倾角,磁偏角和材料磁化率的影响;随着地磁场强度增大,管道磁异常呈线性增大;研究成果将为自主研发高精度磁异常地下管线探测设备奠定理论基础。     

第一性原理对(NaP_3)_n(n=1～5)团簇的几何结构和性质的研究

本文采用第一性原理研究了(NaP_3)_n(n=1~5)团簇的几何结构、能隙、电荷分布以及态密度.研究结果表明:NaP_3团簇为线型结构,是(NaP_3)_n(n=1~5)团簇中的基本单元,随着n增大,团簇转变为环状结构和空间结构;(NaP_3)_3团簇的能隙出现峰值,表明该团簇较其他团簇有较高的稳定性;(NaP_3)_3团簇中对于高能量区域的态密度是由Na 3s和P 3p轨道贡献,其中在费米附近的能量主要由P 3p轨道贡献,对于低能量区域的态密度主要由Na 3s轨道贡献;(NaP_3)_n(n=1~5)团簇中的Na原子电荷分布均为正值,表明电荷总体上是从Na原子转移到P原子.     

Self-sustaining discharges in needle-to-plane geometry with hundreds of microns electrode gaps

Atmospheric pressure needle-to-plane discharges have been explored experimentally in electrode gaps from 100 μm to 400 μm. These discharges can be self-sustained and follow the form of existing empirical formulae describing the current-voltage characteristics of corona discharge. The discharge can also be self-sustained by its lower sustaining voltage applied between the two electrodes once it is ignited by the initial high output voltage from power supply. The experiments of charging aerosol particles by the self-sustaining discharge operating with a lowered power have shown that for particles with a diameter of 46 nm, the charging efficiency attained 43.6%.     

电子垂直入射电离氦原子碰撞机理的理论研究

用3C模型和修正后的3C模型在低能、两个出射电子等能分享几何条件下,对电子垂直入射碰撞电离氦原子的三重微分散射截面进行了理论计算,并把计算结果与实验测量结果进行了比较,系统研究了(e,2e)反应中各种屏蔽效应对氦原子三重微分散射截面的影响,同时对截面中形成各峰的碰撞机理做了详细的探讨.研究结果表明:在入射能较低时,各种屏蔽效应对氦原子的三重微分散射截面幅度以及角分布均存在一定影响,并且形成各峰的碰撞机理直接影响截面的变化规律.     

第一性原理对(NaP3)n(n=1～5)团簇的几何结构和性质的研究

本文采用第一性原理研究了(NaP3)n(n=1～5)团簇的几何结构、能隙、电荷分布以及态密度.研究结果表明: NaP3团簇为线型结构,是(NaP3)n(n=1～5)团簇中的基本单元,随着n增大,团簇转变为环状结构和空间结构,; (NaP3)3团簇的能隙出现峰值, 表明该团簇较其他团簇有较高的稳定性; (NaP3)3团簇中对于高能量区域的态密度是由Na 3s和P 3p轨道贡献,其中在费米附近的能量主要由P 3p轨道贡献, 对于低能量区域的态密度主要由Na 3s轨道贡献; (NaP3)n(n=1～5)团簇中的Na原子电荷分布均为正值, 表明电荷总体上是从Na原子转移到P原子.