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No full textPoznańThe article presents use of PNN to identify ship’s radio stations. Two methods of PNN acceleration are included. The first one is a combination of PNN and Kohonen neural network. The task of Kohonen neural network is to roughly classify radio station. The final identification is performed by PNN. The second speeding up approach consists in using average data instead of original one. Moreover, a modification of PNN decision rule is applied
No full textPoznańThe deterministic quantum transfer-matrix (QTM) technique and its mathematical background are presented. This important tool in computational physics can be applied to a class of the real physical low-dimensional magnetic systems described by the Heisenberg hamiltonian which includes the macroscopic molecular-based spin chains, small size magnetic clusters embedded in some supramolecules and other interesting compounds. In order to convert existing application for the susceptibility calculations to run on the grid, the speed-up and efficiency of parallelization are analyzed on the SGI Origin 3800 platform with p = 128 processor units. Using Message Parallel Interface (MPI) system libraries we find the efficiency of the code of 94% for p = 128 that makes our application suitable for the grid
No full textPoznańThe Poisson’s ratio of anisotropic materials depends, in general, both on a “longitudinal” direction along which the stress is changed and on a “transverse” direction in which the transverse deformation is measured. For cubic media there exist “longitudinal” directions, parallel to the 4-fold and 3-fold axes, for which the Poisson’s ratio does not depend on the “transverse” direction. Depending on the tensor of elastic compliances (or elastic constants), crystals of cubic symmetry can exhibit negative Poisson’s ratio in both these directions (they are called strongly auxetics), in one of them (i.e. either along the 4-fold axis or along the 3-fold one; they are called partially auxetic) or in none of them. For crystals exhibiting 3-fold symmetry axis the Poisson’s ratio along this axis does not depend on the “transverse” direction. For other “longitudinal” directions the Poisson’s ratio depends, in general, on the “transverse” direction. The Poisson’s ratio averaged with respect to the “transverse” direction depends only on the “longitudinal” direction and can be conveniently presented graphically. As an example the f.c.c. hard sphere crystal is considered. It is shown that the average (with respect to “transverse” direction) Poisson’s ratio of the hard sphere crystal is positive for all “longitudinal” directions. One should add, however, that there exist directions for which the (not averaged) Poisson’s ratio of hard spheres is negative
No full textPoznańThe Poincaré plot (PP) is one of the many techniques used for ascertaining the heart rate variability, which in turn is a marker of the activity of the autonomic system. Poincaré plots are very simple to produce, but their preparation involves a few fine points. This paper describes one of them, namely the filtering of data used for the Poincaré plot. We show the correct way of filtering data, present a few results of not filtering or incorrect filtering and demonstrate how proper filtering helps extract interesting information from the data. A few algorithms for preparing Poincaré plots, filtering data and calculating PP descriptors are included. As Matlab’s programming language is the unquestionable standard for data analysis in the medical sciences, we illustrate these algorithms by snippets of code in this language
