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1
Content available remote Wiener-Hopf analysis of diffraction of acoustic waves by a soft/hard half-plane
Ayub M., Mann A. B., Ahmad M., Tiwana M. H.
Archives of Mechanics
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2010
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Vol. 62, nr 2
157-174
EN
In this paper, firstly, the far field due to a line source scattering of acoustic waves by a soft/hard half-plane is investigated. It is observed that if the line source is shifted to a large distance, the results differ from those of [16] by a multiplicative factor. Subsequently, the scattering due to a point source is also examined using the results of line source excitation. Both the problems are solved using the Wiener–Hopf technique and the steepest descent method. Some graphs showing the effects of various parameters on the diffracted field produced by the line source incidence are also plotted.
2
Content available remote The unsteady Couette flow of a second grade fluid n a layer of porous medium
Hayat T., Khan M., Ayub M., Siddiqui A. M.
Archives of Mechanics
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2005
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Vol. 57, nr 5
405--416
EN
In this work, the two Couette flows of a second grade fluid are discussed in a porous layer when (i) bottom plate moves suddenly (ii) bottom plate oscillates. Laplace transform method is used to determine the analytic solutions. Expressions for the velocities, volume fluxes and frictional forces are constructed.
3
Content available remote Scattering by a slit in an infinite conducting screen.
Hayat T., Ayub M., Farid T.
Optica Applicata
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2001
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Vol. 31, nr 3
635-642
EN
Cylindrical wave diffraction by a slit in an infinite, plane, perfectly conducting barrier in a homogeneous biisotropic medium is investigated. The source point is assumed far from the slit so that the incident cylindrical wave is locally plane. The slit is wide and the barrier thin, both with respect to wavelength. The boundary value problem is reduced to a Wiener-Hopf equation and solved approximately
4
Content available remote Propagation of a low frequency electromagnetic pulse generated by an electric dipole in seawater.
Ayub M., Hayat T., Asghar S.
Optica Applicata
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1999
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Vol. 29, nr 4
561-571
EN
An exact analytic solution for the propagation in seawater of low frequency electromagnetic pulse generated by an electric dipole is investigated. The dipole is excited by a rectangular current pulse with a finite, nonzero rise and decay time. The frequency-domain formulas for the downward-travelling field of horizontal electric dipole excited by pulse is Fourier transformed to obtain an explicit expression for the field that is uniformly valid in distance and time. is noted that the present analysis may be used for studying pulse propagation in any highly conductiong medium besides seawater.
5
Content available remote Rectangular Gaussion pulse propagation in sea water.
Ayub M, Asghor A., Butt K.
Optica Applicata
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1998
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Vol. 28, nr 1
17-29
EN
The propagation in sea water of a low-frequency electromagnetic pulse generated by an electric dipole is investigated. The electric dipole is excited by a rectangular Gaussion pulse. The frequency-domain formula for the downward-travelling field is Fourier transformed to obtain an explicit expression for field at any distance in the time domain. The propagation of a rectangular Gaussian pulse as an envelope for a low-frequency burst is also analysed and its anomalous behaviour is determined. Graphs for amplitudes of a single rectangular Gaussian pulse and a burst are displayed and discussed for a range of distances.
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