The VC-1 Video Coding Standard

VC-1 is a new video coding standard developed by Microsoft and standardized by the SMPTE. VC-1 is one of the three video compression algorithms standardized for high definition DVD. With high definition DVD players expecting to support MPEG-2, H.264, and VC-1, end users do not have to be concerned about the coding formats. The VC-1 standard offers a competitive quality-complexity tradeoff compared to H.264, especially for high-definition services. With a diverse digital video market, we can expect to see VC-1 co-existing with H.264 in the next generation of broadband and broadcast video services.     

A note on the theory of spin wave resonance in spiral structures

The appearance of two resonant modes of spin waves with different non-zero wave vectors is theoretically predicted for a magnetic arrangement of the type of an antiferromagnetic spiral combined with weak antiferromagnetism in the direction of the spiral axis. A study is made of the question of the Hamiltonian suitable for possible applications of the chosen magnetic arrangement, and the possibility of energetic stability of the considered magnetic structure for two concrete realistic forms of the Hamiltonian is pointed out.The author expresses his sincere thanks for valuable discussions and stimulating comments to Dr. S. Krupika and Dr. J. Loos, P. Novák and I. Veltruský of the Institute of Solid State Physics of the Czechoslovak Academy of Sciences, and to Assoc. Prof. J. Morkowski and Assoc. Prof. L. Kowalewski of the Polish Academy of Sciences and Poznan University.     

Transdisciplinary aspects of diffusion and magnetocaloric effect

The modeling of magnetocaloric effect (MCE) based on quasiparticle formalism was used to show a possibility to increase our knowledge of diffusion and phase transitions by a transdisciplinary scientific approach. Generalized understanding of diffusion and of some phase transitions was suggested. New relations between MCE and elastic parameters of materials, obtained from modeling procedure, were presented. The paper contains also the short discussion of a necessity to use hypercomplex mathematics in modeling of magnetic processes and specifically in a modeling of MCE. Some remarks concerning nanomaterials are added. This revised version was published online in August 2006 with corrections to the Cover Date.     

Design of interfaces between high speed data converters and high performance FPGAs for software defined radio applications

Telecommunication Systems - Software defined radio (SDR) is a vast and emerging field that requires the design of various technologies such as antenna, RF, IF, and digital baseband subsystems....     

The H.264 Video Coding Standard

The H.264 video coding standard, also known as MPEG AVC, represents the state of the art in video compression. This article provides an overview of the H.264 standard. To help the reader understand the similarities and differences between it and MPEG-2 (and other hybrid video coding standards), the author describes the H.264 features and compare them to functionally similar MPEG-2 features     

Calculation of spin-wave energy and the mean value of Hamiltonian in a noncollinear magnetic sublattice structure by the method of Green's functions

The contribution of this work is the extension of Green's function formalism to the case of noncollinear, canted, 6-sublattice magnetic structure. The external magnetic field was considered. The selfconsistent procedure for calculation of renormalized spin-wave energies and the mean value of the Hamiltonian was discussed on the basis of both Tyablikov's and Callen's decoupling approximations and it was shown that the use of Callen's decoupling requires a preliminary solution of the problem on the basis of simpler decoupling. The equations are analogous to the Callen's equation but the temperature dependent factor has a more general form and instead of an explicit equation for energy there is an implicit equation.     

Noncollinear magnetic structure in a random system of densely packed hard spheres

For an amorphous model system consisting of a random set of 100 identical hard sphere densely packed in a cube with periodical boundary conditions the energies of spiral magnetic structures are investigated. It is shown for a simple model with exponentially decaying antiferromagnetic interaction that a spiral structure may exist displaying a minimum energy. The wavevector of the spiral minimizing the interaction energy depends on the range of interaction: for the short range one the pitch of the spiral is twice as high as that for the longer range of interactions The calculated energies are compared with the interaction energies in s.c., f.c.c., and b.c.c. lattices. It is found that the energy gain in the topologically random system with respect to the magnetically disordered state may be higher than that corresponding to the antiferromagnetic arrangement in a crystal.One of the authors (S. K.) thanks Dr. J. L. Finney for a valuable discussion concerning the computer generation of the random set of hard spheres.     

Influence of amorphous environment on magnetic structure

The influence of disordered medium on the magnetic structure of crystalline clusters is discussed. In a plate-like crystalline cluster with localized moments the disordered magnetic environment leads to preference of a spiral magnetic structure over the antiferromagnetic collinear ordering that would be otherwise realized. By the numerical solution of a specific model qualitative information was obtained about the influence of the exponential rate of decrease of the exchange interaction, plate thickness and degree of disorder of the medium on the magnetic structure of the cluster.     

Spin waves and magnetocaloric effect in two-sublattice antiferrimagnet

The magnetocaloric effect in the stable antiferrimagnetic phase of a two-sublattice uniaxial antiferrimagnet is studied on the basis of the spin wave theory. The negative slope in theH-dependence of the lowest spin-wave energy branch allows the cooling effect with increasing external magnetic fieldH. The dependence of the effect on the strength of exchange and anisotropy and the influence of phonons is discussed in detail.