局部方差在图像质量评价中的应用

将灰度图像的局部方差分布(QLS)作为表征图像结构信息的一个重要特征,对局部方差分布矩阵进行奇异值分解,计算得到相应的奇异值特征向量;通过计算降质图像与原参考图像局部方差矩阵奇异值特征向量的夹角大小度量两图像的结构相似度,实现了对降质图像的质量评价。实验结果表明:局部方差分布更能突出图像的结构特征,评价结果优于传统的均方误差(MSE)、峰值信噪比(PSNR)、结构相似度(SSIM)以及直接评价图像像素分布的奇异值分析(SVD)等方法,与人眼视觉感知效果的一致性较好。     

局部方差在图像质量评价中的应用

将灰度图像的局部方差分布（QLS）作为表征图像结构信息的一个重要特征,对局部方差分布矩阵进行奇异值分解,计算得到相应的奇异值特征向量;通过计算降质图像与原参考图像局部方差矩阵奇异值特征向量的夹角大小度量两图像的结构相似度,实现了对降质图像的质量评价。实验结果表明：局部方差分布更能突出图像的结构特征,评价结果优于传统的均方误差（MSE）、峰值信噪比（PSNR）、结构相似度（SSIM）以及直接评价图像像素分布的奇异值分析（SVD）等方法,与人眼视觉感知效果的一致性较好。     

Finite-temperature theory of local environment effect in FeNi alloy

Finite-temperature theory of local environment effect (LEE) is extended by taking account of the LEE on the amplitude of the local magnetic moments. By use of the improved theory, the finite-temperature magnetism of FeNi alloy is investigated in detail. Distribution of thermally averaged local moments due to the randomness of the atomic configuration are obtained. The magnetization and the internal-field distribution are calculated from them. Present theory explains well the rapid deviation from the Slater-Pauling curve, the downward deviation from the Brillouin curve and the broad internal-field distribution seen by ⁵⁷Fe. In these phenomena the broad distribution of Fe local moments due to the LEE is important.     

椭圆截面金纳米管近场增强特性的研究

本文基于时域有限差分方法(finite difference time domain, FDTD)研究了入射光波长、入射光偏振方向、纳米管几何形状、 管壁厚度及内核和包埋介质的变化对椭圆截面金纳米管近场分布特征的影响. 研究发现, 入射光波长为纳米管等离激元共振波长时, 纳米管近场增强最大; 入射光偏振方向与椭圆长轴夹角的增加会导致管内的场强迅速增大; 椭圆管半短轴变大可以调节纳米管场强分布从两端高、中间低变化为均匀分布; 内核和包埋介质介电常数的增大均会使得纳米管内部及周围场强逐渐减弱.     

Disorder-induced local magnetic moments in weakly correlated metallic systems

We consider the formation and the Kondo effect of local magnetic moments in the Anderson-Hubbard model with off-diagonal disorder. The existence of moments at sites weakly coupled to the environment is deduced in effective medium approximation. The distribution of moments is calculated both deep in the metallic phase and near the metal-insulator transition. We discuss the Kondo quenching of the moments and derive a distribution of local Kondo temperatures.     

From unweighted to weighted networks with local information

In this paper, we analyze an evolving model with local information which can generate a class of networks by choosing different values of the parameter p. The model introduced exhibits the transition from unweighted networks to weighted networks because the distribution of the edge weight can be widely tuned. With the increase in the local information, the degree correlation of the network transforms from assortative to disassortative. We also study the distribution of the degree, strength and edge weight, which all show crossover between exponential and scale-free. Finally, an application of the proposed model to the study of the synchronization is considered. It is concluded that the synchronizability is enhanced when the heterogeneity of the edge weight is reduced.     

Inhomogeneous broadening of local vibrations in spectra of organic molecules in solid matrices

The existence of the inhomogeneous distribution of local vibrational frequencies in addition to the inhomogeneous distribution of pure electronic frequencies in the spectra of impurity molecules is demonstrated by the hole-burning technique. The half-width of the inhomogeneous vibrational distribution is determined.     

Distribution of a local magnetic field in superconductors with an uncorrelated random lattice of abrikosov vortices

The distribution of a local magnetic field near the surface of a uniaxial anisotropic type-II superconductor is determined in the framework of the London model in the case when the Abrikosov vortices are randomly distributed in the superconductor. The distribution of a local magnetic field is obtained as a function of the distance from the surface of the superconductor. It is demonstrated that the shape of the distribution of the local magnetic field near the surface differs substantially from that in the bulk of the superconductor. This difference should be taken into account in interpreting experimental data on the local magnetic field in the surface region of the superconductor and in thin superconducting films (with a thickness of less than or equal to λ, where λ is the depth of penetration of the magnetic field into the superconductor). It is shown that, as in the case of a regular lattice of vortices, the value of λ can be determined from observations of the distribution of the local magnetic field in type-II superconductors with an uncorrelated random lattice of vortices.     

基于局部光流约束的角点匹配算法

提出了一种基于局部光流约束的角点匹配算法。首先采用Harris算子获得当前帧和参考帧的角点,然后以角点的光流特征作为约束条件,根据两帧图像角点集的坐标分布,排除异常角点,完成角点的精确匹配,实现图像之间的高精度运动估计。通过对视频序列进行实验,采用差图法可主观地发现该运动估计算法的有效性;以峰值信噪比作为评价指标,发现原始视频序列的帧间峰值信噪比明显低于仿射视频序列的帧间峰值信噪比。前者的平均值为22.8072,后者的平均值为33.3854,从而客观地说明了该算法的有效性和稳定性。     

复杂网络局部结构的涌现:共同邻居驱动网络演化

在对真实网络的小世界和无标度特性进行了大量深入考量之后,最近的研究热点开始转移到更加细致的局部结构.实证数据显示,大量真实网络具有幂律的低阶集团度分布.这一普适的规律,无法由富者愈富以及熟人推荐的网络生长机理再现.本文提出一种由共同邻居驱动的网络演化模型,该模型能够重现实证研究所观察到的幂律集团度分布,暗示共同邻居驱动是复杂网络局部结构涌现形成的内在机理. 关键词： 复杂网络 演化模型 集团度分布 共同邻居     

Green＇s function formalism in semi-infinite composites： an investigation of local field distribution

In the resonant composites, the formerly developed Green's function formalism (GFF) can be used to compute the local field distribution near resonance. In this paper, we extend the GFF in the infinite network to the semi-infinite networks by the method of image. Using the formalism, we investigate the local field distribution near resonance for the impurity clusters with admittance ε_0 embedded in one semi-infinite network with ε_1. With varying the admittance ε_2 of another semi-infinite network, we find that the local fields in the boundary experience great changes, especially at ε_2=-ε_1. The existence of the boundary enhances the localization of the fields within and around the metallic clusters. Therefore, the intensity of local field is influenced by the arrangement of impurity metallic bonds and its distance from the boundary.     

Refractive index dependent local electric field enhancement in cylindrical gold nanohole

We report on the local electric field characters in a long cylindrical gold nanohole. Theoretical calculation results based on quasi-static model show that the local environmental dielectric constant dependent electric field intensity and field distribution in the gold nanohole show quite unique properties, different from those in the thin gold nanotube. Because of the thick gold wall, no plasmon hybridization exists. So there is only one resonance frequency taking place, and the intense local field has been focused into the gold nanohole. Our main finding is that, the local field in the nanohole is largely dependent on the inner hole refractive index and outer environmental refractive index. The competition between inner hole and outer polarization leads to a non-monotonic change of the local field intensity with increasing the dielectric constant of the nanohole. This refractive index controlled local field enhancement in cylindrical gold nanohole presents a potential for tunable surface-enhanced fluorescence and novel nano-optical biosensing applications.     

Kinematics of edge dislocations. I. Involutive distributions of local slip planes

The geometry of continuous distributions of dislocations and secondary point defects created by these distributions is considered. Particularly, the dependence of a distribution of dislocations on the existence of secondary point defects is modeled by treating dislocations as those located in a time-dependent Riemannian material space describing, in a continuous limit, the influence of these point defects on metric properties of a crystal structure. The notions of local glide systems and involutive distributions of local slip planes are introduced in order to describe, in terms of differential geometry, some aspects of the kinematics of the motion of edge dislocations. The analysis leads, among others, to the definition of a class of distributions of dislocations with a distinguished involutive distribution of local slip planes and such that a formula of mesoscale character describing the influence of edge dislocations on the mean curvature of glide surfaces is valid.     

Time dependent local field distribution and metastable states in the SK-spin-glass

Different sets of metastable states can be reached in glassy systems below some transition temperature depending on initial conditions and details of the dynamics. This is investigated for the Sherrington-Kirkpatrick spin glass model with long ranged interactions. In particular, the time dependent local field distribution and energy are calculated for zero temperature. This is done for a system quenched to zero temperature, slow cooling or simulated annealing, a greedy algorithm and repeated tapping. Results are obtained from Monte-Carlo simulations and a Master-Fokker-Planck approach. A comparison with replica symmetry broken theory, evaluated in high orders, shows that the energies obtained via dynamics are higher than the ground state energy of replica theory. Tapping and simulated annealing yield on the other hand results which are very close to the ground state energy. The local field distribution tends to zero for small fields. This is in contrast to the Edwards flat measure hypothesis. The distribution of energies obtained for different tapping strengths does again not follow the canonical form proposed by Edwards.     

About the background distribution in MR data: a local variance study

A model for the distribution of the sample local variance (SLV) of magnetic resonance data is proposed. It is based on a bimodal Gamma distribution, whose maxima are related to the signal and background areas of the image. The model is valid for single- and multiple-coil systems. The proposed distribution allows us to characterize some signal/background properties in MR data. As an example, the model is used to study the effect of the background size over noise estimation techniques and a method to test the validity of background-based noise estimators is presented.     

Near-field scanning optical microscopy local luminescence studies of rhodamine dye

This article presents results of near-field scanning optical microscope measurement of local luminescence of rhodamine 3B intercalated in montmorillonite samples. We focus on how local topography affects both the excitation and luminescence signals and resulting optical artifacts. The Finite Difference in Time Domain method (FDTD) is used to model the electromagnetic field distribution of the full tip-sample geometry including far-field radiation. Even complex problems like localized luminescence can be simulated computationally using FDTD and these simulations can be used to separate the luminescence signal from topographic artifacts.     

DC magnetization of ferromagnetic amorphous wires with local deformation

Experimental DC (VSM) and theoretical hysteresis loops of a ferromagnetic amorphous wire with a deformation in the middle or exposed to local magnetic fields are investigated. Hysteresis loops show two-stage Barkhausen jumps and staircase relaxation. With a local field at the same position, the loop drastically looses its shape and symmetry depending on the magnitude and the direction of the magnetic bias. A model to explain this behavior is proposed. The proposed model is based on the calculation of the magnetic moment distribution of the domain as a result of domain wall motion and nucleation in the inner core of a ferromagnetic wire and is in a good agreement with the experimental results.     

Kinetic equation for the processes of local reorganization of molecular systems with charged species

A molecular dynamic theory based on the lattice-gas model for the local reorganization of multi-component systems containing charged species is considered. Expressions for the mono- and bimolecular stages of the elementary processes that describe chemical reactions and displacements and rotations of molecules in dense gases and liquids are derived, with consideration given to direct and indirect effects of the initiation of electron and proton transfer. The proposed kinetic equations describe small-scale restructuring of solutions containing components of different sizes under the influence of changes in the external parameters of the molecular system at the kinetic stage of evolution of the system. The theory retains the effects of direct spatial correlations in the distribution of all the components of the mixture with the help of pair distribution functions in the quasi-chemical approximation. The dynamics of the local reorganization of molecules includes the kinetic equations for the local densities and pair distribution functions. The equations derived are intended to describe liquid-phase reactions, ion charge exchange, mutual diffusion of components of different sizes in multicomponent solutions, extraction processes at liquid phase boundaries, and photochemical processes in condensed phases.