Abstracts of papers for

Previous issue vol. 41, no. 1 (2000)

vol. 41, no. 2 (2000)

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Contents of issue 2, vol. 41

Original Contributions

1. D. Rogula, M. Sztyren: Equilibrium configurations of magnetic flux lines in strongly anisotropic superconductors
2. E. Włodarczyk: The backward launching of solids by products of detonation
3. B. Atamaniuk, K. Żuchowski: Two-ion dusty plasma waves and Landau damping
4. D. Spałek: Fourth boundary condition for electromagnetic field
5. K. Kroszczyński: The properties of a strange attractor reconstructed from the time series of tropospheric mean temperature
6. S. Apanasewicz and S. Pawłowski: Using improved impedance boundary conditions to derive distributions of electromagnetic fields
7. S.K. Ghosh, D.K. Nandi: Magnetohydrodynamic fully developed combined convection flow between vertical plates heated asymmetrically

D. Rogula, M. Sztyren: Equilibrium configurations of magnetic flux lines in strongly anisotropic superconductors

The string model is applied to networks of magnetic flux lines in a strongly anisotropic superconducting medium. The notion of vectorial anisotropic string tension is introduced. It is shown that, contrary to the case of isotropic string, the tension is not tangent to the flux line. The equilibrium configurations of flux lines pinned to the anisotropic material are examined. The existence of spontaneously bent extremals, energetically more favorable than straight lines, is proven. The question of degeneracy of the solutions is discussed.

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E. Włodarczyk: The backward launching of solids by products of detonation

The problem of the initial phase of backward launching of the concentrated masses M₁ and M₂ by the compressed products of detonation, was solved in a closed form. It was found that the application of the Gurney formulae to estimate the initial velocity of the explosively driven elements of the shaped charge liner is burdened with a relatively large error. It results from the linear approximation of the flow velocity of the detonation products versus the Lagrangian coordinate (r). This approximation can be used when M₁ = M₂ ł 1, where m is the explosive mass. This condition in the shaped charge ammunition (HEAT), especially in warheads with a heavy casing and thin liner, is not satisfied. Besides, it was shown that the flow velocity of the detonation products changes linearly versus the Eulerian coordinate (x). The constructed solution can be used in the description of the process of shaped charge jet formation.

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B. Atamaniuk, K. Żuchowski: Two-ion dusty plasma waves and Landau damping

The paper analyses the properties of dusty plasmas in the extreme conditions when the free electrons are absent. The nonlinear Korteveg de Vries equation with a nonlocal (integral) term in a small parameter approximation is derived. The conditions are determined when the integral term is essential hence the Landau damping of two-ion-dusty plasma waves is substantial.

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D. Spałek: Fourth boundary condition for electromagnetic field

The paper deals with the problem of boundary condition formulation for an electromagnetic field. The nonlinear boundary condition has been proposed. This condition has been introduced on the basis of Maxwell's equations. The nonlinear condition includes three well-known boundary conditions of Dirichlet, Neumann and Hankel. An example has been provided to show the usefulness of the boundary condition proposed. The fourth boundary condition enables us to reduce the region of numerical analysis.

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K. Kroszczyński: The properties of a strange attractor reconstructed from the time series of tropospheric mean temperature

The correlation dimension and Lyapunov coefficients for a dynamic system constructed on the basis of tropospheric mean temperature time series are presented. The calculations proved that the attractor is strange and his geometrical structure is fractal. The attractor's strangeness results from the existence of positive values of the Lyapunov coefficients. Based upon these results, the estimated time of the dynamic system prediction is 13 days.

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S. Apanasewicz and S. Pawłowski: Using improved impedance boundary conditions to derive distributions of electromagnetic fields

In this paper the improved boundary condition of impedance type the harmonic low-frequency electromagnetic field calculation is presented. It is based on the application of successive approximations in two-dimensional case. As an illustration of the presented method the calculation of electromagnetic field in the neighbourhood of metallic wall is given. A comparison of approximate solutions with the exact one is done (Figs. 3-8).

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S.K. Ghosh, D.K. Nandi: Magnetohydrodynamic fully developed combined convection flow between vertical plates heated asymmetrically

Magnetohydrodynamic (MHD) fully developed flow of a viscous incompressible electrically conducting fluid in a vertical channel during combined convection, with asymmetric heating of the wall, under the influence of a constant pressure gradient and in the presence of an uniform transverse magnetic field, is studied. Exact solution of the governing equation is obtained in a closed form. The solution in a dimensionless form contains two pertinent flow parameters, viz. M (the Hartmann number) and G_r (the Grashof number). The limiting cases of a MHD forced and free convection are analyses, what has not been done earlier in the literature. The occurrence of flow reversal indicates that there arises a flow reversal at the cold wall when r_T = 1 while, for r_T < 1, no flow reversal is possible in the absence of magnetic forces.

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