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Study of three dimensional propagation of waves in hollow poroelastic circular cylinders

Shah S. A.

International Journal of Applied Mechanics and Engineering

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2015

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Vol. 20, no. 3

565--587

EN

Employing Biot’s theory of wave propagation in liquid saturated porous media, waves propagating in a hollow poroelastic circular cylinder of infinite extent are investigated. General frequency equations for propagation of waves are obtained each for a pervious and an impervious surface. Degenerate cases of the general frequency equations of pervious and impervious surfaces, when the longitudinal wavenumber k and angular wavenumber n are zero, are considered. When k=0, the plane-strain vibrations and longitudinal shear vibrations are uncoupled and when […] these are coupled. It is seen that the frequency equation of longitudinal shear vibrations is independent of the nature of the surface. When the angular (or circumferential) wavenumber is zero, i.e., n=0, axially symmetric vibrations and torsional vibrations are uncoupled. For n[…] these vibrations are coupled. The frequency equation of torsional vibrations is independent of the nature of the surface. By ignoring liquid effects, the results of a purely elastic solid are obtained as a special case.

2

Surface instability of a semi-infinite isotropic laminated plate under surface van der Waals forces

Wang X., Xu Y., Zhou K.

Archives of Mechanics

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2015

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Vol. 67, nr 2

137--155

EN

By means of complex variable method, the present work demonstrates that the surface of a semi-infinite isotropic laminated plate that is being attracted to a rigid contactor through van der Waals forces is always unstable. Two distinct surface instability modes are identified, and their wavenumbers and wavelengths are presented in concise and simple expressions. Furthermore, the two wavenumbers and wavelengths are completely determined by three elastic parameters of the laminated plate, three parameters related to the interactions between the surface and the contactor, and three parameters related to surface energy.

3

Phase velocity and attenuation of longitudinal shear vibrations of hollow poroelastic cylinders

Ahmed Shah S., Javvad Hussaini S.

International Journal of Applied Mechanics and Engineering

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2014

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Vol. 19, no. 2

337--346

EN

The present paper is devoted to the study of phase velocity and attenuation of longitudinal shear vibrations of hollow poroelastic circular cylinders in the presence of dissipation. The explicit expressions for phase velocity and attenuation of longitudinal shear vibrations are derived. The frequency equation of longitudinal shear vibrations and modes obtained in a previous paper are used to compute the phase velocity and attenuation for different dissipations for thin and thick poroelastic cylindrical shells and poroelastic solid cylinder. The physical parameters of sandstone saturated with kerosene and sandstone saturated with water are used for the purpose of computation. It is found that the phase velocity is linear beyond certain frequency. Phase velocity is smaller for a typical anti-symmetric mode compared to the flexural mode. It is greater for the second mode than that of the first mode. Also the phase velocity is larger for a thin poroelastic cylindrical shell than that of a thick poroelastic cylindrical shell. The same is true for attenuation also. Attenuation is very high for the considered dissipations and it increases with the increase in dissipation.

4

UV spectral analysis of N- and C- substituted diazaphenanthrenes

Deska M., Śliwa W.

Prace Naukowe. Chemia i Ochrona Środowiska / Akademia im. Jana Długosza w Częstochowie

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2008

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Vol. 12

91-101

EN

In the work the UV spectra of N- and C- substituted diazaphenanthrenes are presented along with comparison to spectra of parent 1,5-, 1,6- and 4,6-diazaphenanthrenes. The UV spectral values of considered compounds have been calculated by AM1 method and the correlation of experimental and calculated wavenumber values has been made.

PL

W pracy przedstawiono widma UV N- i C-podstawionych diazafenantrenów oraz porównano je z widmami niepodstawionych diazafenantrenów. Stosując metodę AM1 obliczono wartości dotyczące widm UV dla rozważanych związków oraz przeprowadzono korelacje doświadczalnych i obliczonych wartości ich liczb falowych.

5

AM1 CI and DFT B-3 LYP study of diazaphenanthrenesulfonamides

Dondela B., Chrząstek L.

Prace Naukowe. Chemia i Ochrona Środowiska / Akademia im. Jana Długosza w Częstochowie

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2008

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Vol. 12

103-111

EN

Two diazaphenanthrenesulfonamides have been synthesized. For calculation of theoretical UV values of these compounds the AM1 CI method has been used; their geometry optimisation was made with AM1 CI and DFT B-3 LYP methods.

PL

Przeprowadzono syntezę dwóch diazafenantrenosulfonamidów. W celu obliczenia teoretycznych wartości widm UV tych związków użyto metodę AM1 CI; optymalizację ich geometrii wykonano metodami AM1 CI i DFT B-3 LYP.

6

Migracja w czasie odwrotnym w dziedzinie liczb falowych (kx, kz)

Kostecki A., Półchłopek A.

Prace Instytutu Górnictwa Naftowego i Gazownictwa

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2000

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nr 110 wyd. konferencyjne

185--188

EN

Herein presents some results of revers-time migration in wavenumber (kx, k/) domain. The reverse time-migration was performed by the solution in form of Neumann's series and by Taylor's ones. We present also back-time extrapolation based on a pseudo-spectral method (Taylor's series) which accounts for surface irregular topography.