Abstracts of papers for

Previous issue vol. 43, no. 2 (2002)

vol. 43, no. 3 (2002)

Next issue vol. 43, no. 4 (2002)

Contents of issue 3, vol. 43

1. D. Rogula : Statistical physics of string-like objects in condensed matter. Dislocations and superconducting vortices
2. J.E. Allen : On the charging of a dust particle immersed in a plasma: theory and experiment
3. M. Aleksiejuk and M.A. Knyazev : Anharmonic polarization of ferroelectric ceramics in alternating field. I: Large damping
4. M. Sztyren : Bi-continuum modelling of layered structures and crystalline interfaces
5. Cz. Rymarz : Modeling of material continua with defected and ordered microstructures
6. M. Borysiewicz, S. Potempski and R. Żelazny : Implementation of pre-operational version of RODOS System in the Center for Radiological Events of the National Atomic Energy Agency in Poland
7. J. Avsec and M. Marčič : Comparison of thermodynamic functions calculated by means of various methods
8. K.M. Gawrylczyk : Sensitivity analysis of electromagnetic quantities by means of FEM

   Brief Notes

9. T. Lenkowska-Czerwińska : Inhomogeneous superconductivity and vortices in the stripe states
10. S. Poria and H.P Mazumdar : Oscillating magnetohydrodynamic flow past a rigid plane wall

D. Rogula : Statistical physics of string-like objects in condensed matter. Dislocations and superconducting vortices

Material media containing dense distributions of linear, string-like objects are considered. Dislocation lines in structured solids and supercurrent vortices in type-II superconductors are exemplifications of such objects. The strings are assumed to carry a quantized Abelian topological charge, such as the Burgers vector or magnetic flux. The basic formulations of statistical physics of such systems are discussed. Contrary to the special cases of rectilinear strings, which reduce effectively to 2D systems of point-like particles, the statistical physics of 3D networks of flexible strings is treated on a stand alone basis from the first principles. The presented description takes into account the quenched, thermal, and quantum disorder in a unified way. Implications for the macroscopic setting are discussed.

Contents

J.E. Allen : On the charging of a dust particle immersed in a plasma: theory and experiment

A review is given of the theory of charging of a dust particle according to the Orbital Motion Limited (OML) theory. This is followed by a summary of a more complete orbital theory that includes the concept of an absorption radius, or effective potential barrier, for the positive ions. Measurements of the charge acquired by a dust particle are then described, using the method of damped dust oscillations employed at Oxford.

Contents

M. Aleksiejuk and M.A. Knyazev : Anharmonic polarization of ferroelectric ceramics in alternating field. I: Large damping

Polarization of ferroelectric ceramics in an alternating electric field with frequency ω in a case when damping is large is considered. For the two-type of ions phenomenological model of ferroelectrics which includes only two types of ions of the crystalic lattice, the nonlinear anharmonic equation for polarization is considered. By perturbation method the solution of this equation in the first order in anharmonicity coefficient is constructed. It is shown that an additional oscillations of polarisation with frequency ω/2 and phase shift between real and imaginary components of polarization appeared.

Contents

M. Sztyren : Bi-continuum modelling of layered structures and crystalline interfaces

To the memory of Ekkehart Kröner.
The bi-continuum model composed of two interpenetrating and dynamically coupled material continua is analysed as a simplified but relatively accurate way to describe some physical phenomena in crystalline solids. The essential novelty of our approach consists in treating a crystalline medium as a bi-continuum, even if the crystalline lattice is structurally single-component. Particular attention is paid to the oscillatory behaviour of solutions on the atomic level. Starting from a discrete atomic chain, the basic formulation of the bi-continuum model is derived. The essential features of the model, including accuracy of the results as functions of physical parameters, are discussed.

Contents

Cz. Rymarz : Modeling of material continua with defected and ordered microstructures

The paper contains a short presentation of some models of material continua with microstructure applying the methods of differential geometry. Two main kinds of microstructure are considered: dislocation, disclination, and unholonomic defects in plasticity, nematic liquid crystal as an example of oriented medium. The aim of this presentation is to illustrate the effectiveness of the methods of differential geometry in construction of the theory of microstructural media.

Contents

M. Borysiewicz, S. Potempski and R. Żelazny : Implementation of pre-operational version of RODOS System in the Center for Radiological Events of the National Atomic Energy Agency in Poland

This paper is devoted to the comprehensive description of the implementation of the RODOS System in the Center for Radiological Events (CEZAR) of the National Atomic Energy Agency in Poland. First the history of the RODOS Project of the European Commission is presented, followed by the description of the structure and modules of this comprehensive Software Package, aimed to assist in the management of the nuclear emergency problems following the nuclear accident in Europe. Then the adaptation of the software to Polish national conditions is explained taking into account the radiological data prevailing on the Polish territory. All the data bases connected with meteorology, contamination transport parameters in humans and their ecological systems have been collected and applied to meet the specific dietary habits, soil structures, agricultural situation and other specific condition in this country. Those data have been introduced into the system after appropriate adaptations to the specific requirements of the modules of the RODOS System. Furthermore, the network system connected with the RODOS pre-operational version in CEZAR is described enabling on-line cooperation with the Institute of Meteorology and Water Management (IMWM) and the Central Laboratory for Radiological Protection (CLOR) as well as with the Institute of Atomic Energy (IAE), which plays the role of Technical Support Organization with respect to this System. IAE has participated in the development of the RODOS System within the 4-th and 5-th Research Frameworks of EU and acknowledges here with gratitude the Implementation Grant from the State Committee of Scientific Research and National Atomic Energy Agency in Poland. This Grant has created the basis for the implementation of the RODOS System in Poland within the framework and assistance of the ECHO contract of the EU.

Contents

J. Avsec and M. Marčič : Comparison of thermodynamic functions calculated by means of various methods

The paper deals with the Lennard-Jones fluid and presents the mathematical model of computating thermodynamic functions of state in the liquid and gas domain by means of statistical thermodynamics. To calculate the thermodynamic properties of a real fluid, we used the Johnson-Zollweg-Gubbins model based on the modified Benedict-Webb-Rubin equation of state, the Chunxi-Yigui-Jiufang equation of state based on the simple perturbation theory, and the complex Tang-Tong-Lu model based on the solution of the Ornstein-Zernike equation obtained by means of the perturbation theory. The analytical results are compared with the thermodynamical data, and with the results obtained from classical thermodynamics.

Contents

K.M. Gawrylczyk : Sensitivity analysis of electromagnetic quantities by means of FEM

Sensitivity analysis determines the dependence of global or local electromagnetic quantities on geometrical or physical parameters expressed in the form of an objective function. The final aim of the field calculation methods is generally the design of an electromagnetic device. Solution of inverse problem on the basis of the finite elements method (FEM) makes the optimal shape design possible, as well as the identification of material cracks and flaws inside the conducting materials with the help of the eddy-current method. These tasks can be defined similarly for recognition of the spatial distribution of material parameters. The recognition takes place in iterative manner, basing on gradient information derived from the sensitivity analysis. The work deals with sensitivity evaluation in conjunction with finite element algorithms. It will be shown that the sensitivity analysis necessary to solve an inverse problem, requires only a low additional calculation cost.

Contents

T. Lenkowska-Czerwińska : Inhomogeneous superconductivity and vortices in the stripe states

Spatially inhomogeneous features in the spin and charge structures have been indicated in the number of experiments on high temperature materials e.g. La_2-xSr_xCuO₄. The simple realization of this state is striped domain wall where charges form a nanoscale linear pattern in an antiferromagnetically ordered isolator. These represent a nanoscale distribution of charge and spin that is believed to be commensurably locked by the tilt distortions of the lattice. The phenomenological model of charge and spin inhomogeneities in the stripe phase of superconducting cuprates on the ground of Ginzburg-Landau theory is proposed. The corresponding free energy for the coupled charge and spin-density wave, and superconducting order parameters is constructed. The phase diagram for inhomogeneous superconducting state is discussed. The effective coherence length and the penetration depth in the London limit are introduced. The critical magnetic fields and the energy of the isolated vortex line are obtained.

Contents

S. Poria and H.P Mazumdar : Oscillating magnetohydrodynamic flow past a rigid plane wall

In this paper, the effects of a magnetic field acting perpendicularly to the direction of an oscillatory, viscous, conducting, incompressible fluid stream past a fixed plane wall is investigated. The problem is first converted to the Stokes second problem by introducing a new coordinate system and prescribing the appropriate forms for the pressure gradient corresponding to two sets of boundary and initial conditions. Solutions to the problem are then obtained by invoking an invariance principle, and computed numerically for different values of a magnetic parameter. The effects of the transversal magnetic field on the velocity profiles are finally discussed.

Contents