Acoustic Plane Wave Diffraction from a Circular Soft Ring

2019 ◽  
Vol 105 (5) ◽  
pp. 805-813 ◽  
Author(s):  
Victor Lysechko ◽  
Dozyslav Kuryliak
Keyword(s):  
Near Field ◽  
Mode Matching ◽  
Algebraic Equations ◽  
Axially Symmetric ◽  
Total Field ◽  
Linear Algebraic Equations ◽  
Comparison Of The Results ◽  
Plane Wave Diffraction ◽  
Analytical Regularization ◽  
Rigorous Method

The paper presents the implementation of the rigorous method of analytical regularization to the canonical problem of axially-symmetric diff raction from a soft ring. The series equations of the problem are reduced to an infinite series of linear algebraic equations (ISLAE) and the technique of analytical regularization is applied. Finally, the resulting matrix equation is the ISLAE of the second kind and can be solved numerically by the truncation method with any desired accuracy. The near field in the vicinity of the aperture of the ring is presented in the form of maps of the normalised total field. The far field features of the ring are obtained and discussed. The validation of our calculation is confirmed by testing of the mode matching conditions and through the comparison of the results with those for a disc.

Electromagnetic field of the circular magnetic source in biconical section

2020 ◽  
Vol 2020 (48) ◽  
pp. 5-10
Author(s):  
O.M. Sharabura ◽  
◽  
D.B. Kuryliak ◽  
Keyword(s):  
Field Pattern ◽  
Geometrical Parameters ◽  
Algebraic Equations ◽  
Axially Symmetric ◽  
Reduction Procedure ◽  
Infinite Systems ◽  
Linear Algebraic Equations ◽  
Regularization Techniques ◽  
Far Field Pattern ◽  
Analytical Regularization

The problem of axially-symmetric electromagnetic wave diffraction from the perfectly conducting biconical scatterer formed by the finite cone placed in the semi-infinite conical region is solved rigorously using the mode-matching and analytical regularization techniques. The problem is reduced to the infinite systems of linear algebraic equations (ISLAE) of the second kind. The obtained equations admit the reduction procedure and can be solved with a given accuracy for any geometrical parameters and frequency. The numerical examples of the solution are presented. The analysis of the source location influences on the far-field pattern for different geometrical parameters of the bicone is carried out.

An Analysis of the Large Deflections of Beams using the Rayleigh-Ritz Finite Element Method

1968 ◽  
Vol 19 (4) ◽  
pp. 357-367 ◽  
Author(s):  
A. C. Walker ◽  
D. G. Hall
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Method ◽  
Large Deflection ◽  
Energy Functional ◽  
Algebraic Equations ◽  
Linear Algebraic Equations ◽  
Non Linear ◽  
Comparison Of The Results ◽  
Element Method

SummaryThe Rayleigh-Ritz finite element method is used to obtain an approximate solution of the exact non-linear energy functional describing the large deflection bending behaviour of a simply-supported inextensible uniform beam subjected to point loads. The solution of the non-linear algebraic equations resulting from the use of this method is effected, using three different techniques, and comparisons are made regarding the accuracy and computing effort involved in each. A description is given of an experimental investigation of the problem and comparison of the results with those of the numerical method, and of the available exact continuum analyses, indicates that the numerical method provides satisfactory predictions for the non-linear beam behaviour for deflections up to one quarter of the beam’s length.

scholarly journals Radiation analysis of sound waves from semi-infinite coated pipe

2018 ◽  
Vol 18 (1) ◽  
pp. 92-111 ◽  
Author(s):  
Burhan Tiryakioglu ◽  
Ahmet Demir
Keyword(s):  
Fourier Transform ◽  
Sound Waves ◽  
Algebraic Equations ◽  
Total Field ◽  
Hopf Equation ◽  
Waveguide Modes ◽  
Linear Algebraic Equations ◽  
Pipe Radius ◽  
Expansion Coefficients ◽  
The Fourier Transform

An analytical solution is presented for the problem of radiation of sound waves from a semi-infinite circular cylindrical coated pipe which is partially lined from inside. By stating the total field in duct region in terms of normal waveguide modes (Dini’s series) and using the Fourier transform technique elsewhere, we obtain a Wiener–Hopf equation whose solution involving three sets of infinitely many unknown expansion coefficients satisfying three systems of linear algebraic equations. This system is solved numerically and the influence of some parameters (pipe radius, impedances, extension, etc.) on the radiation phenomenon is displayed graphically.

Diffraction by a set of three parallel impedance half-planes with the one amidst located in the opposite direction

2002 ◽  
Vol 80 (8) ◽  
pp. 893-909 ◽  
Author(s):  
G Çinar ◽  
A Büyükaksoy
Keyword(s):  
Fourier Transform ◽  
Opposite Direction ◽  
Infinite System ◽  
Plane Waves ◽  
Mode Matching ◽  
Algebraic Equations ◽  
Matching Method ◽  
Linear Algebraic Equations ◽  
Expansion Coefficients ◽  
The One

The problem of diffraction of plane waves by a set of three parallel half-planes with different surface impedances on upper and lower faces where the one in the middle is placed in the opposite direction, is solved by the mode-matching method where available, and by Fourier-transform technique elsewhere. The solution includes two independent Wiener–Hopf equations each involving an infinite number of expansion coefficients that satisfy an infinite system of linear algebraic equations. PACS No.: 41.20J

Stress Distribution in Bonded Dissimilar Materials Containing Circular or Ring-Shaped Cavities

1965 ◽  
Vol 32 (4) ◽  
pp. 829-836 ◽  
Author(s):  
F. Erdogan
Keyword(s):  
Integral Equations ◽  
Complete Solution ◽  
Closed Form Solution ◽  
Form Solution ◽  
Fredholm Integral Equations ◽  
Infinite Plane ◽  
Algebraic Equations ◽  
Axially Symmetric ◽  
Linear Algebraic Equations ◽  
Penny Shaped Crack

The general problem of two semi-infinite elastic media with different properties bonded to each other along a plane and containing a series of concentric ring-shaped flat cavities is considered. Using the Green’s functions for the semi-infinite plane, the problem is formulated as a system of simultaneous singular integral equations. Closed-form solution of the corresponding dominant system with Cauchy kernels is given. To obtain the complete solution, a technique reducing the problem to solving a system of linear algebraic equations rather than a pair of Fredholm integral equations is outlined. The examples for which the contact stresses are plotted include the bonded media with an axially symmetric external notch subject to axial load or homogeneous temperature changes and the case of penny-shaped crack.

LOW-FREQUENCY ACOUSTIC SCATTERING OF A PLANE WAVE FROM A SOFT AND HARD TORUS

2007 ◽  
Vol 15 (02) ◽  
pp. 181-197 ◽  
Author(s):  
GEORGE VENKOV
Keyword(s):  
Separation Of Variables ◽  
Near Field ◽  
Scattering Problem ◽  
Acoustic Scattering ◽  
Low Frequency ◽  
Diagonal Form ◽  
Legendre Functions ◽  
Algebraic Equations ◽  
Analytical Technique ◽  
Linear Algebraic Equations

A plane acoustic wave is scattered by either a soft or a hard small torus. The incident wave has a wavelength which is much larger than the characteristic dimension of the scatterer and thus the low-frequency approximation method is applicable to the scattering problem. It is shown that there exists exactly one toroidal coordinate system that fits the given geometry. The R-separation of variables is utilized to obtain the series expansion of the fields in terms of toroidal harmonics (half-integer Legendre functions of first and second kind). The scattering problem for the soft torus is solved analytically for the near field, governing the leading two low-frequency coefficients, as well as for the far field, where both the amplitude and the cross-section are evaluated. The scattering problem for the hard torus appears to be much more complicated in calculations. The Neumann boundary condition on the surface of the torus leads to a three-term recurrence relation for the series coefficients corresponding to the scattered fields. Thus, the potential boundary-value problem for the leading low-frequency approximations is reduced to infinite systems of linear algebraic equations with three-diagonal matrices. An analytical technique for solving systems of diagonal form is developed.

Sound Radiation from the Perforated End of a Lined Duct

2019 ◽  
Vol 105 (4) ◽  
pp. 591-599 ◽  
Author(s):  
Burhan Tiryakioglu
Keyword(s):  
Infinite System ◽  
Normal Modes ◽  
Mode Matching ◽  
Algebraic Equations ◽  
Matching Method ◽  
Linear Algebraic Equations ◽  
Matching Technique ◽  
Specific Impedance ◽  
Expansion Coefficients ◽  
The Fourier Transform

Radiation of sound wave through a lined duct with perforated end is analyzed rigorously. The problem considered is axisymmetric. By using the Fourier transform technique in conjunction with the Mode Matching method, the related boundary value problem is formulated as a Wiener-Hopf (W-H) equation. The Mode-Matching technique allows us to express the field component defined in the waveguide region in terms of normal modes. The solution involves a set of infinitely many expansion coefficients satisfying an infinite system of linear algebraic equations. The numerical solution of this system is obtained for different parameters of the problem such as the surface impedances, specific impedance of the perforated screen and their effects on the radiation phenomenon are shown graphically.

scholarly journals Diffraction of sound waves by a lined cylindrical cavity

2020 ◽  
Vol 19 (1-2) ◽  
pp. 38-56
Author(s):  
Burhan Tiryakioglu
Keyword(s):  
Mode Matching ◽  
Sound Waves ◽  
Algebraic Equations ◽  
Hopf Equation ◽  
Matching Method ◽  
Infinite Systems ◽  
Linear Algebraic Equations ◽  
The Fourier Transform ◽  
Sound Diffraction ◽  
Selection Of

In this paper, diffraction of sound waves through a lined cavity is analyzed rigorously. The inner–outer surfaces of the cavity and the base of the cavity are coated with three different absorbing linings. By using the Fourier transform technique in conjunction with the Mode-Matching method, the related boundary value problem is formulated as a Wiener–Hopf equation. In the solution, two infinite sets of unknown coefficients are involved that satisfy two infinite systems of linear algebraic equations. Numerical solution of this system is obtained for various values of the parameters of the problem. The graphical results are also presented which show that how efficiently the sound diffraction can be reduced by selection of problem parameters.

On Improved Approximate Solution of the Fredholm Integral Equation

2006 ◽  
Vol 6 (3) ◽  
pp. 264-268
Author(s):  
G. Berikelashvili ◽  
G. Karkarashvili
Keyword(s):  
Integral Equation ◽  
Approximate Solution ◽  
Fredholm Integral Equation ◽  
Algebraic Equations ◽  
Order Convergence ◽  
One Dimensional ◽  
Averaging Operator ◽  
Linear Algebraic Equations ◽  
Convergence Solution

AbstractA method of approximate solution of the linear one-dimensional Fredholm integral equation of the second kind is constructed. With the help of the Steklov averaging operator the integral equation is approximated by a system of linear algebraic equations. On the basis of the approximation used an increased order convergence solution has been obtained.

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