Abstracts of papers for

Previous issue vol. 45, no. 2 (2004)

vol. 45, no. 3 (2004)

Next issue vol. 45, no. 4 (2004)

Contents of issue 3, vol. 45

1. P. Koniorczyk, J. Zmywaczyk, M. Kowalski: Effect of surface emissivity on reduction in thermal conductivity in a view of simple analytical model and radiative transfer equation
2. E.J. Danicki: Efficiency estimation of a contactless comb transducer
3. M. Aleksiejuk: The picosecond ultrasonic waves in Au/V multilayers
4. R. Brojewski, B. Jakubiak, J. Jasiński: Impact of the surface temperature and the zonal drift on the orographic bifurcation and blocking in 2l-baroclinic model of the troposphere

5. A.A. Vantsyan: Magnetoelastic forced and free vibrations of ferromagnetic plates in direct transverse or longitudinal electromagnetic fields
6. D. Rogula: Extended Ginzburg-Landau theory of magnetically active anisotropic superconductors
7. J. Píchal: Conversion of photographically recorded interference pattern into equidenses

P. Koniorczyk, J. Zmywaczyk, M. Kowalski: Effect of surface emissivity on reduction in thermal conductivity in a view of simple analytical model and radiative transfer equation

The problem of modelling a `thickness effect curve' in semitransparent media, using a simple analytical model based on division of the thermal conductivity thickness dependence k(z) (for a sample thickness l) into three regions of different widths, is presented in this paper. The limiting value of the sample thickness l_lim is comparable (in our opinion) with the mean free path of a photon and corresponds to its initial region of thermal conductivity expressed as an exponential function of the absorption coefficient κ and sample thickness l. To validate the proposed method, the results of analytical solution have been compared with the exact solution of the 1-D model of coupled radiation and conduction heat transfer in an emitting and absorbing medium.

Keywords: radiative-conductive heat transfer, reduction of thermal conductivity.

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E.J. Danicki: Efficiency estimation of a contactless comb transducer

A simplified analytical model of comb transducer is proposed to evaluate its efficiency when working through a thickness-optimized air gap between the comb and the substrate. The resonant condition in the air gap improves the transmission of acoustic energy between the comb and the substrate. This results in a better efficiency of the surface wave generation in the substrate; its estimated value is about 1% per comb tooth.

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M. Aleksiejuk: The picosecond ultrasonic waves in Au/V multilayers

A study of picosecond ultrasonic waves propagation in Au/V superlattices in period 30-120 ? is presented. Au/V structures were grown by molecular beam epitaxy (MBE) on MgO substrate. High-frequency ultrasonic waves in Au/V structures were generated by using ultrashort laser pulse excitation and detected in real time by measuring the strain-induced change in reflectivity with pump-probe technique. High-frequency oscillations were detected over the first 150 ps. Series of the oscilations were generated when therminated layer is made of the material with the lowest acoustic impedance (vanadium for Au/V multilayer). The author attributes these oscillations to surface mode localized in the frequency band gap of the dispersion curve.

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R. Brojewski, B. Jakubiak, J. Jasiński: Impact of the surface temperature and the zonal drift on the orographic bifurcation and blocking in 2l-baroclinic model of the troposphere

The paper presents a 2-layer baroclinic model of the troposphere in geostrophic approximation that enables to obtain, after application of the Galerkin method, a fairly simple low-parametric dynamic system describing the phenomena of nonlinear interactions, bifurcations, blocking and auto-regulation in the atmosphere. It enables to take into consideration such basic factors molding the atmospheric dynamics like heat exchange with the surface, orography, vertical diversity of the zonal drift and hydrostatic stability. Conditions of orographic bifurcation of the model were investigated and confronted with the results obtained from a barotropic model. Impact of the zonal thermal diversity of the surface and the vertical diversity of the zonal drift of the troposphere on the orographic bifurcation was assessed. Oscillation character analysis was made in the dynamic system after Hopf bifurcation of the second kind.

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Brief Notes

A.A. Vantsyan: Magnetoelastic forced and free vibrations of ferromagnetic plates in direct transverse or longitudinal electromagnetic fields

The experimental investigations of the problem of bending vibrations of magnetoelastic and ferromagnetic plates are carried out. The amplitudes of displacements, velocities and accelerations are evaluated and the corresponding curves as functions of the magnetic field, longitudinal or transverse, are drawn. It is shown that they have extremal character. Also graphs of frequencies of free vibrations of plates as functions of magnetic field are given, what is in agreement with the spatial theory developed by ourselves.

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D. Rogula: Extended Ginzburg-Landau theory of magnetically active anisotropic superconductors

A formulation of thermodynamical theory of magnetically active, anisotropic materials admitting coexistence of the superconductivity and magnetic order is proposed. The theory is based on the Ginzburg-Landau approach extended to multi-component order parameters and the states of thermodynamic quasi-equilibrium far from the superconducting phase transition. The field equations are derived under assumption of the (U(1) gauge invariance. The questions of exact anisotropic similarity transformations as well as approximate anisotropic scaling are discussed.

Keywords: superconductors, magnetic order, Ginzburg-Landau theory, variational principles.

Contents

J. Píchal: Conversion of photographically recorded interference pattern into equidenses

The paper presents a method simplifying the photographically registered interference fringe contours or profiles. The classical, commonly used, laboured and time-consuming method of fringe profile photometrical evaluation is replaced by a method of processing, based on the Sabattier effect reducing the interference fringes to equidenses - locuses of points of maximal density (of "blackening"). The described method substantially speeds up the interference fringe evaluation and might be useful also in cases when due to poor quality of the recorded interferogram, other methods of evaluation are in practice inapplicable.

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