15,171 research outputs found
A bifurcated circular waveguide problem
No full textThis is a pre-copy-editing, author-produced PDF of an article accepted for publication in IMA Journal of Applied Mathematics following peer review. The definitive publisher-authenticated version A D Rawlins. A bifurcated circular waveguide problem. J.I.M.A. 54 (1995) 59-81. Oxford University press is available online at: http://imamat.oxfordjournals.org/cgi/reprint/54/1/59.pdfA rigorous and exact solution is obtained for the problem of the radiation of sound from a semi-infinite rigid duct inserted axially into a larger acoustically lined tube of infinite length. The solution to this problem is obtained by the Wiener-Hopf technique. The transmission and reflection coefficients, when the fundamental mode propagates in the semi-infinite tube, are obtained. The present results could be of use for exhaust design, and as a possible instrument for impedance measurement
A note on Wiener-Hopf matrix factorisation
No full textThis is a pre-copy-editing, author-produced PDF of an article accepted for publication in Quarterly Journal of Mechanics and Applied Mathematics following peer review. The definitive publisher-authenticated version Rawlins, A D (1985). A note on Wiener-Hopf matrix factorisation. Quarterly Journal of Mechanics and Applied Mathematics. 38 (3) 433-437 is available online at: http://qjmam.oxfordjournals.org/cgi/reprint/38/3/433.pdfIn this paper the most general class of 2 x 2 matrices is determined which permit a
Wiener-Hopf factorization by the procedure of Rawlins and Williams (1). According
to this procedure, the factorization problem is reduced to a matrix Hilbert problem
on a half-line, where the matrix involved in the Hilbert problem is required to have
zero diagonal elements
The method of finite-product extraction and an application to Wiener-Hopf theory
No full textCopyright @ The Author, 2011. The publisher version of the article can be accessed at the link below.In this work we describe a simple method for finding approximate representations for special functions which are entire transcendental functions that can be represented by infinite products. This method replaces the infinite product by a finite polynomial and Gamma functions. This approximate representation is shown in the case of Bessel functions to be very accurate over a large range of parameter values. These approximate expressions can be useful for finding the roots of a transcendental equation and the Wiener-Hopf factorization of functions involving such Bessel functions.The method is shown to be potentially useful for other transcendental andWiener-Hopf problems, which involve other entire functions that have infinite product representations
A Green's function for diffraction by a rational wedge
No full textIn this paper we derive an expression for the point source Green's function for the
reduced wave equation, valid in an angular sector whose angle is equal to a rational
multiple of 77. This Green's function can be used to find new expressions for the field
produced by the diffraction of a spherical wave by a wedge whose angle can be
expressed as a rational multiple of n. The expressions obtained will be in the form of
source terms and real integrals representing the diffracted field. The general result
obtained is used to derive a new representation for the solution of the problem of diffraction by a mixed hard-soft half plane
High frequency diffraction of an electromagnetic plane wave by an imperfectly conducting rectangular cylinder
No full textCopyright @ 2011 IEEEWe shall consider the the problem of determining the scattered far wave field produced when a plane E-polarized wave is incident on an imperfectly conducting rectangular cylinder. By using the the uniform asymptotic solution for the problem of the diffraction of a plane wave by a right-angled impedance wedge, in conjunction with Keller's method, the a high frequency far field solution to the problem is given
Cylindrical-wave diffraction by a rational wedge
No full textIn this paper, new expressions for the field produced by the diffraction of a cylindrical wave by a wedge, whose angle can be expressed as a rational multiple of π are given. The solutions are expressed in terms of source terms and real integrals that represent the diffracted field. The general result obtained includes as special cases, Macdonald's solution for diffraction by a half plane, a solution for Carslaw's problem of diffraction by a wedge of open angle 2π\3, and a new representation for the solution of the problem of diffraction by a mixed soft-hard half plane
Diffraction by a half-plane in a moving fluid
No full textIn the following work we solve the problem of the diffraction of a plane sound wave by an impedance half-plane in a moving fluid. Expressions for the total far field are derived for both the leading edge and trailing edge situations. In the trailing edge situation the problem has the added complication of a trailing vortex sheet or wake. Hence a Kutta-Joukowski edge condition is imposed to ensure that the fluid velocity is finite at the edge and to obtain a unique solution to the problem
Link stability estimation based on link connectivity changes in mobile ad-hoc networks
No full textDear Wang,
Re: Link Stability Estimation Based on Link Connectivity Changes in Mobile Ad-hoc Networks
I have not been able to assess if this is an author version peer-reviewed or is it an author version non peer reviewed. Could you please clarify this so I can proceed to add your paper to Spiral. Spiral digital repository only accept peer-reviewed papers.
30/11/12 author has confirmed peer reviewe
A note on the factorization of matrices occurring in Wiener-Hopf problems
No full textSimple expressions for the Wiener-Hopf factors of a certain matrix considered by Daniele are given
A note on a camouflage pursuit problem
No full textThe version available is a preprint of the full and final published article which is accessible at the link below.Copyright © The author 2010. Published by Oxford University Press; all rights reserved. For Permissions, please email: [email protected] camouflage is a pursuit strategy whereby a predator moves towards a prey while appearing stationary to the prey except for the change in its perceived cross section as it approaches. If the effect of cross section size with distance is ignored then this means that the target is unable to discern that the aggressor is moving. The aggressor appears to be at its initial position or is camouflaged by a stationary object in the background. We shall derive a closed form solution to the problem of camouflage pursuit for a particular situation. Although general differential equations have already been derived for this strategy they have not been solved in closed form
- …
