Analysis of fluid flow and energy transport in Czochralski's process

In this paper the conjugate fluid flow and energy transport problem (involving conduction-convection-radiation heat transfer) resulting from the Czochralski crystal growth process is analysed. The solidifying material is treated as a pure and semitransparent substance with material properties depending neither on temperature nor on the wavelength. The solution of the problem is obtained iteratively using two computer codes: FLUENT, a commercial CFD package, and BEM-based in-house code capable of analysing the radiative heat transfer in the entire computational domain.Obtained results not only show velocity field and temperature distribution within the bodies under consideration but also demonstrate the influence of thermal radiation on these quantities.     

A Spurious Equilibria-free Learning Algorithm for the Blind Separation of Non-zoer Skewness Signals

We present a new learning algorithm for the blind separation of independent source signals having non-zero skewness (the 3rd-order cumulant) (the source signals have non-symmetric probability distribution.), from their linear mixtures. It is shown that for a class of source signals whose probability distribution functions is not symmetric, a simple adaptive learning algorithm using quadratic function (f(x)=x²) is very efficient for blind source separation task. It is proved that all stable equilibria of the proposed learning algorithm are desirable solutions. Extensive computer simulation experiments confirmed the validity of the proposed algorithm.     

Rough Sets in Reasoning about Vague Concepts

We discuss the rough set approach to some challenging problems that are of great importance for making progress in many applications. Among such challenges are the following ones.     

Methods of Image Compression by PHL Transform

In this paper an image data compression scheme based on Periodic Haar Piecewise-Linear (PHL) transform and quantization tables is proposed. Effectiveness of the compression for different classes of images is evaluated. The comparison of the compression quality using PHL and DCT transforms is given.     

Modification of Dugdale model to include the work hardening and in- and out-of-plane constraints

In the paper the classical Dugdale model has been generalized taking into account the influence of the specimen thickness, in-plane constraint as well as the effect of the strain hardening on the level of stress distribution within the strip yield zone (SYZ). Modification has been performed utilizing Huber, Mises, Hencky as well as Tresca yield hypotheses and Guo Wanlin Tz coefficient. Results are presented in a form useful for applications. As an example, the modified model has been applied to draw the failure assessment diagram (FAD). New FAD’s have been compared with others adopted from the SINTAP procedures.     

Formulation of Presliding Domain Non-local Memory Hysteretic Loops Based Upon Modified Maxwell Slip Model

In this paper, we investigate formulation of non-local memory effect hysteretic loops in presliding domain of friction by examining the dynamic responses of a single-degree-of-freedom friction oscillator. We modify the Maxwell slip model introducing characteristic features of asperities and perform detailed examination of the system from two perspectives. The first one, termed by us as microscale, presents contribution of each individual asperity to the total friction force, whereas the second one, termed by us as macroscale, concerns friction force behaviour of the whole model treated as the unity, with a special emphasis on non-local memory effect hysteretic loops formulation, complemented by time responses.     

Selective Behaviour of Honeybees in Acquiring European Propolis Plant Precursors

Honey bees harvest resins from various plant species and use them in the hive as propolis. While there have been a number of studies concerning the chemical composition of this antimicrobial product, little is known about selective behavior and bee preference when different potential plant sources of resin are available. The main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition. Samples of propolis originating from temperate zones of Europe and the supposed botanical precursors of the product were analyzed. Taxonomical markers of bud resins of two white birch species, aspen, black poplar, horse-chestnut, black alder, and Scots pine were determined through GC-MS analysis. All these trees have been reported as sources of propolis, but comparisons of the chemical composition of their bud resins with the compositions of propolis samples from seven European countries have demonstrated the presence of taxonomical markers only from black poplar, aspen, and one species of birch. This suggests selective behavior during the collection of bud resins by honeybees. To examine the causes of such selectivity, the antimicrobial properties of bud resins were determined. Horse-chestnut resins had lower antimicrobial activity than the other resins which did not differ significantly.     

Effective Ozone Generation in Oxygen Using a Mesh Electrode in an Ozonizer with Variable Linear Velocity

Results of studies on ozone synthesis under discharges proceeding in a metal mesh-ceramic dielectric system have been presented. The experiments were carried out in the reactor with unique reaction space geometry, in which the reacting gas flew with consequently increasing linear velocity. The high voltage electrode was made of a metal mesh, which caused intensification of the gas mixing in the reaction space. Using a simple reactor with one-side cooling of the reaction space, high ozone maximum concentrations (100 g/Nm³) and energy efficiencies (180–200 g/kWh) were obtained at 25 °C.     

A new didactic approach to statistical analysis of measurement data for the evaluation of measurement uncertainty – “SAM–EMU”

This paper describes assumptions, aims, methodology, content and consortium make up of a European project (SAM–EMU) founded under the Erasmus Lifelong Learning Programme. The project has developed learning materials in the field of evaluation of measurement uncertainty. It is available in the form of a multimedia web based course, which has many advantages. This format is commonly accepted as a good way to prepare an EU wide vocational training vehicle. The course is available in English.