Singularity-free approach for the evaluation of the matrix elements in the context of the method of moments based on the use of closed-form expressions for the fields radiated by the subdomain basis functions

2010 ◽  
Author(s):  
C Pelletti ◽  
K Panayappan ◽  
R Mittra ◽  
A Monorchio
Keyword(s):  
Closed Form ◽  
Method Of Moments ◽  
Basis Functions ◽  
Matrix Elements ◽  
The Matrix

Matrix Elements of the Linearized Collision Operator for Multi-temperature Gas-mixtures

1978 ◽  
Vol 33 (4) ◽  
pp. 480-492
Author(s):  
Ulrich Weinert
Keyword(s):  
Collision Operator ◽  
Basis Functions ◽  
Inelastic Collisions ◽  
Matrix Elements ◽  
Flux Vector ◽  
Balance Equations ◽  
Heat Flux Vector ◽  
The Matrix ◽  
Boltzmann Collision Operator ◽  
Linearized Collision Operator

For a multi-component and multi-temperature gas-mixture the matrix elements of the linearized Boltzmann collision operator are investigated for isotropic interaction potentials. The representation by means of Burnett basis functions simplifies the algebraic structure and enables closed expressions for the general results, which can also be used for an investigation of inelastic collisions. For the elastic case those collision terms are given explicitely which appear in the balance equations for mass, momentum, energy and heat flux-vector.

Karhunen-Loève Basis Functions Of Kolmogorov Turbulence In The Sphere (Baltic Astronomy, 17, 383, 2008, Erratum)

2010 ◽  
Vol 19 (1-2) ◽  
Author(s):  
Richard J. Mathar
Keyword(s):  
Basis Functions ◽  
Eigenvalue Equation ◽  
Matrix Elements ◽  
Outer Scale ◽  
Von Karman ◽  
Kolmogorov Turbulence ◽  
The Matrix ◽  
Von Kármán

AbstractThe previously published factor, which scales the matrix elements of the eigenvalue equation as a finite outer scale of the von-Kármán model is switched on, is corrected.

scholarly journals GENERALIZATION OF THE GELL–MANN DECONTRACTION FORMULA FOR sl(n,ℝ) AND su(n) ALGEBRAS

2011 ◽  
Vol 08 (02) ◽  
pp. 395-410 ◽  
Author(s):  
IGOR SALOM ◽  
DJORDJE ŠIJAČKI
Keyword(s):  
Closed Form ◽  
Lie Algebra ◽  
Unitary Representations ◽  
Irreducible Representations ◽  
Algebraic Expression ◽  
Matrix Elements ◽  
Group Manifold ◽  
The Matrix

The so-called Gell–Mann or decontraction formula is proposed as an algebraic expression inverse to the Inönü–Wigner Lie algebra contraction. It is tailored to express the Lie algebra elements in terms of the corresponding contracted ones. In the case of sl (n,ℝ) and su (n) algebras, contracted w.r.t. so (n) subalgebras, this formula is generally not valid, and applies only in the cases of some algebra representations. A generalization of the Gell–Mann formula for sl (n,ℝ) and su (n) algebras, that is valid for all tensorial, spinorial, (non)unitary representations, is obtained in a group manifold framework of the SO(n) and/or Spin (n) group. The generalized formula is simple, concise and of ample application potentiality. The matrix elements of the [Formula: see text], i.e. SU(n)/SO(n), generators are determined, by making use of the generalized formula, in a closed form for all irreducible representations.

scholarly journals On the Modular Operator of Mutli-component Regions in Chiral CFT

2021 ◽  
Author(s):  
Stefan Hollands
Keyword(s):  
Field Theory ◽  
Integral Equation ◽  
Hilbert Problem ◽  
Matrix Elements ◽  
New Approach ◽  
Conformal Field ◽  
The Matrix ◽  
Kms Condition ◽  
Modular Operator ◽  
Riemann Hilbert Problem

AbstractWe introduce a new approach to find the Tomita–Takesaki modular flow for multi-component regions in general chiral conformal field theory. Our method is based on locality and analyticity of primary fields as well as the so-called Kubo–Martin–Schwinger (KMS) condition. These features can be used to transform the problem to a Riemann–Hilbert problem on a covering of the complex plane cut along the regions, which is equivalent to an integral equation for the matrix elements of the modular Hamiltonian. Examples are considered.

scholarly journals Analytical angular solutions for the atom–diatom interaction potential in a basis set of products of two spherical harmonics: two approaches

2021 ◽  
Author(s):  
Mariusz Pawlak ◽  
Marcin Stachowiak
Keyword(s):  
Spherical Harmonics ◽  
Interaction Potential ◽  
Chem Phys ◽  
Basis Set ◽  
Matrix Elements ◽  
Trigonometric Functions ◽  
Variational Theory ◽  
Molecular Collision ◽  
The Matrix ◽  
Analytical Expressions

AbstractWe present general analytical expressions for the matrix elements of the atom–diatom interaction potential, expanded in terms of Legendre polynomials, in a basis set of products of two spherical harmonics, especially significant to the recently developed adiabatic variational theory for cold molecular collision experiments [J. Chem. Phys. 143, 074114 (2015); J. Phys. Chem. A 121, 2194 (2017)]. We used two approaches in our studies. The first involves the evaluation of the integral containing trigonometric functions with arbitrary powers. The second approach is based on the theorem of addition of spherical harmonics.

scholarly journals Closed-Form Expressions for Numerical Evaluation of Self-Impedance Terms Involved on Wire Antenna Analysis by the Method of Moments

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1316
Author(s):  
Carlos-Ivan Paez-Rueda ◽  
Arturo Fajardo ◽  
Manuel Pérez ◽  
Gabriel Perilla
Keyword(s):  
Numerical Integration ◽  
Method Of Moments ◽  
Computing Time ◽  
Basis Functions ◽  
Wire Antenna ◽  
Complex Geometries ◽  
Point Matching ◽  
Piecewise Constant ◽  
Matching Procedure ◽  
Time Required

This paper proposes new closed expressions of self-impedance using the Method of Moments with the Point Matching Procedure and piecewise constant and linear basis functions in different configurations, which allow saving computing time for the solution of wire antennas with complex geometries. The new expressions have complexity O(1) with well-defined theoretical bound errors. They were compared with an adaptive numerical integration. We obtain an accuracy between 7 and 16 digits depending on the chosen basis function and segmentation used. Besides, the computing time involved in the calculation of the self-impedance terms was evaluated and compared with the time required by the adaptative quadrature integration solution of the same problem. Expressions have a run-time bounded between 50 and 200 times faster than an adaptive numerical integration assuming full computation of all constant of the expressions.

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