Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 3

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Melting as an Instability of Crystal Structure with respect to Transverse Acoustic Wave, Quasi-Harmonic Approach

100%
Czachor A.
Acta Physica Polonica A
|
2012
|
vol. 122
|
issue 2
365-369
EN
It is suggested that the precursor of melting in some crystals can be a macroscopic shear deformation such as the transverse sound wave. This hypothesis is examined basing on the quasi-harmonic approach to lattice dynamics within the two-body ion-ion concept of interaction in metals. One finds that due to the temperature induced modification of effective ion-ion interaction appearing in the quasi-harmonic approximation the crystal ceases to support propagation of transverse sound waves when its temperature approaches a certain critical temperature T_{cr}, understood here to be the melting temperature T_{m}.
2
Content available remote

Energy Spectrum for the System of N Ising Spins with Identical Spin-Spin Coupling K/N - Anatomy of Phase Transition

100%
Czachor A.
Acta Physica Polonica A
|
2008
|
vol. 113
|
issue 4
1161-1169
EN
For the Kittel-Shore-Kac interspin coupling K/N between N Ising spins the ferromagnetic phase transition in specific heat vs. T plot has appeared in literature as a purely mathematical phenomenon, via the exact calculation of the sum of states Z(T) and subsequent differentiations with respect to temperature T. Physical nature of the transition remains in such derivation invisible. As it is expected to be related to the interaction/temperature competition in populating energy levels of the system, in this paper we construct the density of energy states D(E) (or energy spectrum) of such systems, both for the ferromagnetic (K>0) and antiferromagnetic (K<0) coupling between spins. This allows one to see the essence of the difference between these systems as related to the discrete vs. quasi-continuous shape of the spectra at low energy states.
3
Publication available in full text mode
Content available

Determination of Capillary Motion of Water in Bricks Using Neutron Radiography

51%
Czachor A., El-Ghany El-Abd A., Milczarek J.
Acta Physica Polonica A
|
2002
|
vol. 102
|
issue 2
245-252
EN
Vertical migration of water in several porous materials has been directly observed and recorded with the recently installed neutron and gamma radiography facility at the MARIA reactor of Institute of Atomic Energy, Świerk. The density profiles of water in samples were obtained from the optical density of digitised images. A simple model (representing the porous material as the collection of capillary tubes of various radii) has been introduced to describe the liquid transport in porous materials in terms of capillary motion. The equation for viscous movement of water in porous material in presence of the gravitation is proposed. A good agreement of the calculated density profiles for vertical water migration with the data collected for siliceous bricks suggests that the thinnest capillary tubes determine the upper edge of the water density profile.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.