Asymptotics of Raynal-Revai coefficients at large hypermomentum

The Raynal-Revai coefficients are studied as the Wigner D functions of O(6) group generated by the kinematical rotation of two reduced Jacobi vectors in six-dimensional three-body space. These coefficients are represented as one-dimensional integrals with kernels equal to double sums of the Clebsh-Gordan coefficients and associated Legendre polynomials. Using this representation we derive the asymptotics of the Raynal-Revai coefficients at large values of the hypermomentum. The text was submitted by the author in English.     

Spectral solvers for spherical elliptic problems

A new family of direct spectral solvers for the 3D Helmholtz equation in a spherical gap and inside a sphere for nonaxisymmetric problems is presented. A variational formulation (no collocation) is adopted, based on the Fourier expansion and the associated Legendre functions to represent the angular dependence over the sphere and using basis functions generated by Legendre or Jacobi polynomials to represent the radial structure of the solution. In the present method, boundary conditions on the polar axis and at the sphere center are not required and never mentioned, by construction. The spectral solution of the vector Dirichlet problem is also considered, by employing a transformation that uncouples the spherical components of the Fourier modes and that is implemented here for the first time. The condition numbers of the matrices involved in the scalar solvers are computed and the spectral convergence of all the proposed solution algorithms is verified by numerical tests.     

正交各向异性板液/固界面的声反射与声透射

采用Legendre正交多项式法,对液/固界面声波反射和透射系数进行求解。利用Legendre正交多项式对正交各向异性板中的位移解进行展开,推导出板中的应力和波动控制方程。联立液/固界面的边界条件和波动控制方程,建立线性无关方程组,用以计算液/固界面的反射和透射系数及Legendre多项式的展开系数,计算所得铝板液/固界面的反射和透射系数与传递矩阵法的计算结果吻合良好。以单向纤维增强复合材料板为例,在不同的方位角下,分析了反射和透射系数随斜入射角度、入射波频率的变化关系,以及板中声场的位移分布。所取Legendre正交多项式截止阶数越大,可用来计算的频厚积范围越大。研究拓展了Legendre正交多项式法的适用范围,为材料力学性能的声学测量提供了理论基础。      

Entropic Inequalities and Properties of Some Special Functions

Using known entropic and information inequalities, we obtain new inequalities for some classical polynomials. We consider examples of Jacobi and Legendre polynomials.     

A numerical study of fractional rheological models and fractional Newell-Whitehead-Segel equation with non-local and non-singular kernel

In the recent years, few type of fractional derivatives which have non-local and non-singular kernel are introduced. In this work, we present fractional rheological models and Newell-Whitehead-Segel equations with non-local and non-singular kernel. For solving these equations, we present a spectral collocation method based on the shifted Legendre polynomials. To do this, we extend the unknown functions and its derivatives using the shifted Legendre basis. These expansions and the properties of the shifted Legendre polynomials along with the spectral collocation method will help us to reduce the main problem to a set of nonlinear algebraic equations. Finally, The accuracy and efficiency of the proposed method are reported by some illustrative examples.     

xF 3 structure function based on the associated Jacobi polynomials

We present the results of the Next-to-leading order (NLO) non-singlet QCD analysis of the experimental data of the CCFR collaboration for the xF ₃ structure function of the deep-inelastic scattering of neutrinos on the nucleon in based on the associated Jacobi polynomials expansion of the structure functions. The structure function is reconstructed from its moments by using the expansion in terms of orthogonal associated Jacobi polynomials. Our results of valence quark distributions are in good agreement with the available theoretical models.     

Spatial Moments for the Nonstationary One-Velocity Problem of Transport Theory with Isotropic Scattering. 2. Plane Instantaneous Source

The spatial distribution of the density of particles emitted by a plane infinite isotropic source with a unit surface particle density is reconstructed for the nonstationary one-velocity problem of transport theory by the method of polynomial expansions with the use of Legendre and Hermite polynomials. The diffusion approximation is examined and the boundaries of the spatiotemporal region in which this approximation is valid are estimated.     

Theory of multiple scattering

Consideration is given to problems of obtaining exact and approximate solutions of kinetic equations in the multiple scattering problem. For cross sections which are rational functions of χ² (χ = 2sin(δ/2), δ is the scattering angle) exact solutions are obtained as a series in terms of Legendre polynomials. The limits of validity of the kinetic equation for the distribution function in terms of the variable q = 2sin(?/2) are refined [1] and the solutions of this equation are compared with the exact solutions of the Rutherford and Mott cross sections. The problem of convergence of approximate solutions in the form of a series in terms of Legendre polynomials and a series in powers of 1/B is solved. These approximations are obtained and their limits of validity are determined.     

Parton distribution functions up to NNLO

We calculate the unpolarized parton distribution functions up to NNLO approximation from the QCD analysis of the world DIS data. To study the proton structure functions $F_2(x,Q^2)$ , we need to use the orthogonal polynomials expansion method. This method is very useful to parameterize parton distribution function at the input of $Q_0^2$ . Our calculations for parton distribution functions based on the Jacobi polynomials method are in good agreement with the other theoretical models.     

Nucleon/nuclei polarized structure function,using Jacobi polynomials expansion

We use the constituent quark model to extract polarized parton distributions and finally polarized nucleon structure function.Due to limited experimental data which do not cover whole(x,Q2)plane and to increase the reliability of the fitting,we employ the Jacobi orthogonal polynomials expansion.It will be possible to extract the polarized structure functions for Helium,using the convolution of the nucleon polarized structure functions with the light cone moment distribution.The results are in good agreement with available experimental data and some theoretical models.     

An application of one-sided Jacobi polynomials for spectral modeling of vector fields in polar coordinates

A spectral tau-method is proposed for solving vector field equations defined in polar coordinates. The method employs one-sided Jacobi polynomials as radial expansion functions and Fourier exponentials as azimuthal expansion functions. All the regularity requirements of the vector field at the origin and the physical boundary conditions at a circumferential boundary are exactly satisfied by adjusting the additional tau-coefficients of the radial expansion polynomials of the highest order. The proposed method is applied to linear and nonlinear-dispersive time evolution equations of hyperbolic-type describing internal Kelvin and Poincaré waves in a shallow, stratified lake on a rotating plane.     

Investigation the geodesic motion of three dimensional rotating black holes

We study the geodesic equations in the space-time of neutral Brans–Dicke Dilaton black hole in three dimensions and BTZ black hole. We use the process of separation of the Hamilton–Jacobi equation to obtain the constants of motion. The whole analytical solution of the geodesic equations in the space-times of the intended black holes are shown completely. Moreover, the geodesic equations are solved in terms of Weierstrass elliptic functions. Furthermore, with use of the analytical solution and effective potential technique some trajectories around the black holes are classified. Meanwhile, by analytical solution, effective potential and considering the zeroes of underlying polynomials, some possible orbits are plotted. Finally, we compare our results with Cruz et. al. [17] and we indicate the benefits of the analytical method which is applied in this paper.     

The recurrence relations for the spheroidal functions

The integrable properties of the spheroidal equations are investigated. The shape-invariance property is proved to be retained for the spheroidal equations, for which the recurrence relations are obtained. This is the extension of the recurrence relation of the Legendre polynomials.     

Classical Skew Orthogonal Polynomials and Random Matrices

Skew orthogonal polynomials arise in the calculation of the n-point distribution function for the eigenvalues of ensembles of random matrices with orthogonal or symplectic symmetry. In particular, the distribution functions are completely determined by a certain sum involving the skew orthogonal polynomials. In the case that the eigenvalue probability density function involves a classical weight function, explicit formulas for the skew orthogonal polynomials are given in terms of related orthogonal polynomials, and the structure is used to give a closed-form expression for the sum. This theory treates all classical cases on an equal footing, giving formulas applicable at once to the Hermite, Laguerre, and Jacobi cases.     

Accessible solitons of fractional dimension

We demonstrate that accessible solitons described by an extended Schrödinger equation with the Laplacian of fractional dimension can exist in strongly nonlocal nonlinear media. The soliton solutions of the model are constructed by two special functions, the associated Legendre polynomials and the Laguerre polynomials in the fraction-dimensional space. Our results show that these fractional accessible solitons form a soliton family which includes crescent solitons, and asymmetric single-layer and multi-layer necklace solitons.     

On the spherical harmonics and discrete ordinates methods for azimuth-dependent intensity calculations

It is known that the azimuth-averaged component of the intensity computed from the spherical harmonics method for solving the equation of radiative transfer is “exact” at the Gauss quadrature points. We show that a similar relation holds for higher terms in the Fourier expansion of the intensity but that the results are “exact” at the zeros of the associated Legendre polynomials. The relationship between the discrete ordinates and spherical harmonics methods follows from this discussion. A discrete ordinates quadrature scheme, based on the zeros of the associated Legendre polynomials, is shown to maintain the correspondence of the methods for these problems, as well as providing a better set of points than other methods in use.     

改进的三维分离变量表象方法计算振动光谱

用改进的三维分离变量表象(DVR3D)方法研究了基态电子态H2S和H2O的振动光谱。哈密顿形式在Jacobi坐标下给出,每个坐标都用一组DVR基函数表示.角度部分的DVR基组选择勒让德多项式形式,而径向坐标采用正弦函数形式.为了降低需要对角化的最终哈密顿矩阵的维数,采用连续对角化截断方法.用H2S和H2O振动能级的计算验证算法的正确性.     

任意边界板结构的声辐射模态误差传感器的设计

获取声辐射模态伴随系数是基于声辐射模态理论进行主动结构声控制(ASAC)的重要环节。以往PVDF分布式传感器的设计难点是振速展开受边界条件的限制,其设计过程往往是针对特定边界条件展开的。本文在声辐射模态理论和两维分布式传感器的压电方程的基础上,将板表面振速分布用Legendre多项式展开,给出了两维板结构的PVDF传感器形状与边界条件无关的设计方法。这样设计得到的传感器能应用于任意边界条件和任意振速分布的两维板结构,且实时性好,拓宽了其应用范围。本文还分别以固定边界条件板及在该板中任取一小区域两种情况为例,证明了该设计方法的可行性。     

On computing the Chapman-Enskog and Burnett functions

An expansion and projection technique based on Legendre polynomials is used to solve, in an efficient and accurate way, the Chapman-Enskog equations for viscosity and heat transfer and to compute the Burnett functions required, for example, for Poiseuille-flow problems based on rigid-sphere collisions and the linearized Boltzmann equation.     

On Integrals Involving Universal Associated Legendre Polynomials and Powers of the Factor (1-x2) and Their Byproducts

The associated Legendre polynomials play an important role in the central fields, but in the case of the non-central field we have to introduce the universal associated Legendre polynomials P_l'^m'(x) when studying the modified Pschl-Teller potential and the single ring-shaped potential. We present the evaluations of the integrals involving the universal associated Legendre polynomials and the factor (1-x²)^-p-1 as well as some important byproducts of this integral which are useful in deriving the matrix elements in spin-orbit interaction. The calculations are obtained systematically using some properties of the generalized hypergeometric series.