Image description with Chebyshev-Fourier moments

Chebyshev-Fourier moments for describing images were proposed. After definition of the moments, the multidistortion invariance of the moments was verified. The performance of the moments in describing images was investigated in terms of the normalized image-reconstruction error and the results of the experiments on the noise sensitivity are given.     

基于熵及不变矩特征的图像检索

提出了一种基于熵及不变矩特征的图像检索算法.图像首先被划分为不同分块,结合图像信息熵的概念,提出采用单元熵来描述分块特征,从而将图像转化为由单元熵构成的熵矩阵;在此基础上,利用不变矩来描述该熵矩阵的特征,并在对该特征归一化的基础上用于图像检索.结合不变矩的特性,试验中对算法的尺度不变性、旋转不变性、平移不变性及对噪声的不敏感性进行了验证,试验结果证明了算法的有效性.同时,由于熵的对称特性,算法对于图像灰度的变化也有较强的鲁棒性.     

A generalized description of the elastic properties of nanowires

We report a model of nanowire (NW) mechanics that describes force vs displacement curves over the entire elastic range for diverse wire systems. Due to the clamped-wire measurement configuration, the force response in the linear elastic regime can be linear or nonlinear, depending on the system and the wire displacement. For Au NWs the response is essentially linear since yielding occurs prior to the onset of the inherent nonlinearity, while for Si NWs the force response is highly nonlinear, followed by brittle fracture. Since the method describes the entire range of elastic deformation, it unequivocally identifies the yield points in both of these materials.     

Image analysis by fast improved radial harmonic-Fourier moments algorithm

Radial harmonic-Fourier moments (RHFMs) are popular for image reconstruction and invariant pattern recognition due to their properties of translation, scaling and rotation invariant. RHFMs possess lower computation complexity as compared to Zernike moments and Bessel-Fourier moments. However, they always suffer from discontinuity, numerical instability near the center of image, and reconstruction error, especially have a rise for higher order of moments. In this paper, an improvement of radial harmonic-Fourier moments (IRHFMs) is proposed for effectively avoiding the above-mentioned problems.In this paper, a 2D fast Fourier transform algorithm also is applied to the image matrix to obtain the IRHFMs. Simulation experimental results demonstrate the proposed IRHFMs perform better than traditional RHFMs and other classic orthogonal moments including the latest image moments, for example, polar harmonic Fourier moments in terms of the image reconstruction capability and rotation invariant recognition accuracy in noise-free and noisy conditions.     

Computation of higher‐order moments of generalized polynomial chaos expansions

Because of the complexity of fluid flow solvers, non‐intrusive uncertainty quantification techniques have been developed in aerodynamic simulations in order to compute the quantities of interest required in an optimization process, for example. The objective function is commonly expressed in terms of moments of these quantities, such as the mean, standard deviation, or even higher‐order moments. Polynomial surrogate models based on polynomial chaos expansions have often been implemented in this respect. The original approach of uncertainty quantification using polynomial chaos is however intrusive. It is based on a Galerkin‐type formulation of the model equations to derive the governing equations for the polynomial expansion coefficients. Third‐order, indeed fourth‐order moments of the polynomials are needed in this analysis. Besides, both intrusive and non‐intrusive approaches call for their computation provided that higher‐order moments of the quantities of interest need to be post‐processed. In most applications, they are evaluated by Gauss quadratures and eventually stored for use throughout the computations. In this paper, analytical formulas are rather considered for the moments of the continuous polynomials of the Askey scheme, so that they can be evaluated by quadrature‐free procedures instead. Matlab^© codes have been developed for this purpose and tested by comparisons with Gauss quadratures. Copyright © 2017 John Wiley & Sons, Ltd.     

A self-consistent method for the description of the generalized conductivity of heterogeneous systems

Journal of Engineering Physics and Thermophysics - A generalization is presented of the self-consistent field method for the determination of the effective conductivity of heterogeneous materials...     

Double-layered Aurivillius-type ferroelectrics with magnetic moments

We have synthesized the double-layer Aurivillius phase Bi₂LnNbTiO₉ where Ln = Nd-Gd, Bi. All compounds adopt the orthorhombic polar space group A2₁am. The magnetic Ln-ion occupies the cuboctahedral position in the middle of the perovskite double-layer, and thus controls the octahedral tilt of the perovskite block. This tilt modifies the ferroelectric displacement of the (Nb,Ti) towards the octahedral faces. This provides a mechanism to systematically modify the polarization. Mn-substitution on the (Nb,Ti) site for Ln = Bi is homogeneous up to x = 0.2. The magnetic moments of Ln do not order down to 5 K.     

Coping with conflict at constitutional moments

The theme of this paper is the dynamics through which politicalorder and organized government is constituted and reconstitutedin democratic contexts. Key questions are how basic politicalrules evolve and change and the possible significance of reflection,deliberate design and explicit constitutional policy. In democraciesa focus on reflection and choice requires an understanding ofhow political support is mobilized and acquiescence, agreementand allegiance are achieved. It is important to analyze howconstitution making may turn a political system with enduringtensions and conflicts into an organized system of democraticgovernance, cooperation and problem solving.     

DCB-specimen loaded with uneven bending moments

A double cantilever beam specimen loaded with uneven bending moments (DCB-UBM) is proposed for mixed mode fracture mechanics characterisation of adhesive joints, laminates and multilayers. A linear elastic fracture mechanics analysis gives the energy release rate and mode mixity analytically for both isotropic and orthotropic materials. By varying the ratio between the two applied moments, the crack tip stress state can be varied from pure mode I to pure mode II for the same specimen geometry. The specimen allows stable crack growth. A special test fixture is developed to create uneven bending moments. As a preliminary example, the DCB-UBM specimen was used for characterising fracture of adhesive joints between two laminates of thermoset glass fibre reinforced plastic.     

Estimating an endpoint with high-order moments

We present a new method for estimating the endpoint of a unidimensional sample when the distribution function decreases at a polynomial rate to zero in the neighborhood of the endpoint. The estimator is based on the use of high-order moments of the variable of interest. It is assumed that the order of the moments goes to infinity, and we give conditions on its rate of divergence to get the asymptotic normality of the estimator. The good performance of the estimator is illustrated on some finite sample situations.     

Kernel density maximum entropy method with generalized moments for evaluating probability distributions,including tails,from a small sample of data

In this paper, a novel method to determine the distribution of a random variable from a sample of data is presented. The approach is called generalized kernel density maximum entropy method, because it adopts a kernel density representation of the target distribution, while its free parameters are determined through the principle of maximum entropy (ME). Here, the ME solution is determined by assuming that the available information is represented from generalized moments, which include as their subsets the power and the fractional ones. The proposed method has several important features: (1) applicable to distributions with any kind of support, (2) computational efficiency because the ME solution is simply obtained as a set of systems of linear equations, (3) good trade‐off between bias and variance, and (4) good estimates of the tails of the distribution, in the presence of samples of small size. Moreover, the joint application of generalized kernel density maximum entropy with a bootstrap resampling allows to define credible bounds of the target distribution. The method is first benchmarked through an example of stochastic dynamic analysis. Subsequently, it is used to evaluate the seismic fragility functions of a reinforced concrete frame, from the knowledge of a small set of available ground motions.     

Image analysis by pseudo-Jacobi (p = 4, q = 3)-Fourier moments

Pseudo-Jacobi (p = 4, q = 3)-Fourier moments (PJFMs) based on Jacobi polynomials are described. The new orthogonal radial polynomials have almost uniformly distributed (n + 2) zeros in the region of small radial distance 0 < or = r < or = 1. Both theoretical and experimental results indicate that PJFMs are better than orthogonal Fourier-Mellin moments in terms of reconstruction errors and signal-to-noise ratio. The PJFMs are normalized to shift, rotation, scale, and intensity invariance, and some pattern-recognition experiments are described.     

Simulation of random vectors with given moments

We extend in this article the simulation method of scalar random variables with given moments, which was developed initially by Devroye, to n-dimensional random vectors. Using the conditional distribution approach, we show that the vector simulation problem can be reduced to simulate scalar random variables with given moments, which are solutions of given linear systems.     

镜像时刻

本月我们将带你走进镜像世界,感受简单却具有非凡吸引力的映像艺术。镜像总是能赋予一代又一代摄影师丰富的灵感,可能是因为它能轻易营造出充满漂亮色彩,影调和图案的抽象画面。它们如此受欢迎的另一个原因是映像拍摄的主体在我们身边随处可见,所以,你完全不必跋山涉水舟车劳顿地找寻这样的镜头。     

Multidistortion-invariant image recognition with radial harmonic Fourier moments

We propose radial harmonic Fourier moments, which are shifting, scaling, rotation, and intensity invariant. Compared with Chebyshev-Fourier moments, the new moments have superior performance near the origin and better ability to describe small images in terms of image-reconstruction errors and noise sensitivity. A multidistortion-invariant pattern-recognition experiment was performed with radial harmonic Fourier moments.     

结合Zernike矩的多尺度模板形状匹配

针对形状匹配中小波表达对起始点依赖的问题,提出一种结合Zernike矩的多尺度模板进行形状匹配的方法。该算法对输入图像进行预处理后提取目标轮廓,经过归一化处理得到目标形状的平移、尺度不变的链状表达,再通过小波变换进行多尺度分析;引入Zernike矩,利用Zernike矩的特性,实现小波表达的旋转不变性,解决了小波变换对起始点的依赖。匹配过程是以小波表达的各阶Zernike矩为特征向量,在由粗到精的尺度上进行的。实验结果表明,对于同一目标,原图像与旋转不同角度的图像的正确匹配率为91％。该算法适用于轮廓较明显的目标。     

Perturbation theory for the diffusion equation by use of the moments of the generalized temporal point-spread function. I. Theory

We approach the perturbative solution to the diffusion equation for the case of absorbing inclusions embedded in a heterogeneous scattering medium by using general properties of the radiative transfer equation and the solution of the Fredholm equation of the second kind given by the Neumann series. The terms of the Neumann series are used to obtain the expression of the moments of the generalized temporal point-spread function derived in transport theory. The moments are calculated independently by using Monte Carlo simulations for validation of the theory. While the mixed moments are correctly derived from the theory by using the solution of the diffusion equation in the geometry of interest, in order to obtain the self moments we should reframe the problem in transport theory and use a suitable solution of the radiative transfer equation for the calculation of the multiple integrals of the corresponding Neumann series. Since the rigorous theory leads to impractical formulas, in order to simplify and speed up the calculation of the self moments, we propose a heuristic method based on the calculation of only a single integral and some scaling parameters. We also propose simple quadrature rules for the calculation of the mixed moments for speeding up the computation of perturbations due to multiple defects. The theory can be developed in the continuous-wave domain, the time domain, and the frequency domain. In a companion paper [J. Opt. Soc. Am. A23, 2119 (2006)] we discuss the conditions of applicability of the theory in practical cases found in diffuse optical imaging of biological tissues.     

Particle electric dipole moments

Measurements of particle electric dipole moments (EDMs) continue to put powerful constraints on theories of T-symmetry and CP-symmetry violation, which form currently one of the most prominent fields in particle physics. EDM measurements have been concentrated on neutral systems such as the neutron and atoms and molecules. These measurements allow one to deduce, in turn, the electric dipole moments of the fundamental fermions, that is, the lighter leptons and quarks and also those of some heavy nuclei.