A model for semiconductor quantum dot molecule based on the current spin density functional theory

Based on the current spin density functional theory, a theoretical model of three vertically aligned semiconductor quantum dots is proposed and numerically studied. This quantum dot molecule (QDM) model is treated with realistic hard-wall confinement potential and external magnetic field in three-dimensional setting. Using the effective-mass approximation with band nonparabolicity, the many-body Hamiltonian results in a cubic eigenvalue problem from a finite difference discretization. A self-consistent algorithm for solving the Schrödinger-Poisson system by using the Jacobi-Davidson method and GMRES is given to illustrate the Kohn-Sham orbitals and energies of six electrons in the molecule with some magnetic fields. It is shown that the six electrons residing in the central dot at zero magnetic field can be changed to such that each dot contains two electrons with some feasible magnetic field. The Förster-Dexter resonant energy transfer may therefore be generated by two individual QDMs. This may motivate a new paradigm of Fermionic qubits for quantum computing in solid-state systems.     

A Least Squares Approach to Escalator Algorithms for Adaptive Filtering

In this paper, we introduce an escalator (ESC) algorithm based on the least squares (LS) criterion. The proposed algorithm is relatively insensitive to the eigenvalue spread ratio (ESR) of an input signal and has a faster convergence speed than the conventional ESC algorithms. This algorithm exploits the fast adaptation ability of least squares methods and the orthogonalization property of the ESC structure. From the simulation results, the proposed algorithm shows superior convergence performance.     

Bandpass filters using periodically loaded combline resonators

A novel combline filter is proposed for cellular‐radio base stations. The Q‐factor is significantly improved. The eigenvalue equation is expressed with the single‐team approximation in the gap region of the combline resonator. A two‐pole combline filter is designed. The calculation, simulation, and experiment results are presented and are in good agreement. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

An analytical and numerical study of the two-dimensional Bratu equation

Bratu's problem, which is the nonlinear eigenvalue equationu+ exp(u)=0 withu=0 on the walls of the unit square and as the eigenvalue, is used to develop several themes on applications of Chebyshev pseudospectral methods. The first is the importance ofsymmetry: because of invariance under the C₄ rotation group and parity in bothx andy, one can slash the size of the basis set by a factor of eight and reduce the CPU time by three orders of magnitude. Second, the pseudospectral method is ananalytical as well as a numerical tool: the simple approximation3.2A exp(–0.64A), whereA is the maximum value ofu(x, y), is derived via collocation with but a single interpolation point, but is quantitatively accurate for small and moderateA. Third, the Newton-Kantorovich/Chebyshev pseudospectral algorithm is so efficient that it is possible to compute good numerical solutions—five decimal places—on amicrocomputer inbasic. Fourth, asymptotic estimates of the Chebyshev coefficients can be very misleading: the coefficients for moderately or strongly nonlinear solutions to Bratu's equations fall off exponentially rather than algebraically withv untilv is so large that one has already obtained several decimal places of accuracy. The corner singularities, which dominate the behavior of the Chebyshev coefficients in thelimit v, are so weak as to be irrelevant, and replacing Bratu's problem by a more complicated and realistic equation would merely exaggerate the unimportance of the corner branch points even more.     

隐目标回归算法设计研究

对常用的回归方法进行研究.此类方法虽然几何解释明确、易于求解,但均须事先确定(或假定)变量间的因果关系,再考虑建模,在实际应用中,对于很难确定变量的因果关系的问题,如物联网数据分析,上述方法就会失效.为此,提出一种无需假定因变量的隐目标回归方法.该方法易于核化,可以推广到非线性回归问题.通过人工数据和国际标准数据集上的实验验证了所提算法的有效性.     

基于 IFPUG功能点分析方法改进特征值因子的应用研究*

论文阐述了功能点分析方法的计算步骤,并采用IFPUG分析方法对一个接近完成的软件开发项目进行了评估,并结合国内标准提出了改进后的系统特征值评估模型,用六个特性的参数来确定一个系统特征值,以此取代IFPUG功能点分析方法中的调整因子。结果表明：改进后的功能点分析方法在对所开发的软件项目的度量上具有更高的精确度,更接近项目开发的实际。     

基于主成分分析中的几类问题的计算公式及结论

讨论了主成分分析中的几类问题的计算方法,重点揭示在协方差矩阵中对角元素相同时的第一主成分及贡献率和对角元素不同时的主成分贡献率．经讨论后给出有关计算公式,并说明这些计算公式在多元统计分析中的实际作用     

对称Toeplitz—plus—Hankel矩阵特征值的快速算法

利用了n阶对称Toeplitz—plus—Hankel矩阵的结构特点和对称性,给出了计算该类矩阵所有特征值的一个快速算法．该算法的计算复杂度为o（n^2 logn）,比文献[1—2]所给的算法来得少．     

Bergman空间上的加权复合算子

文章首先给出了Bergman空间La^2上加权复合算子,通过研究该空间上酉加权复合算子和紧自伴加权复合算子的谱、特征向量以及特征子空间,进一步完善了Bergman空间La^2上加权复合算子的理论。     

矩阵的Hadamard积最小特征值的下界估计

对A和B是非奇异M矩阵,利用著名的Gerschgorin圆盘定理,给出了B和A-1的Hadamard积B。A-1的最小特征值τ(BA-1)新的下界估计式,此下界估计式改进了现有的几个结果,并且这个下界估计式只涉及矩阵A和B的元素,易于计算.例证表明,所得下界估计式要比现有的下界估计式更加精确.