Large-scale multimedia content delivery over optical networks for interactive TV services

iTVP is a system built for delivery of live TV programming, video-on-demand and audio-on-demand with interactive access over IP networks. It has a nationwide range and is designed to provide service to a high number of concurrent users. Hence, scalability is one of the most important issues. In this paper we described how scalability is achieved in a two-level hierarchical architecture of the delivery system. We present the principles of content caching mechanisms and the management of the resulting distributed content repository. The system is implemented and currently operates in a test installation. Although the range of the test system operations is limited, as far as the number of users and the size of the content repository is concerned, the experience gained with iTVP so far provides an insight into the expected prototype performance. We present a system performance evaluation and describe the experience gained during the iGrid demonstration.     

Detecting evoked potentials with SVD- and ICA-based statistical models.

In the functional diagnostics of human sensor systems, the analysis of stimulus responses embedded in an electroencephalogram (EEG), e.g. evoked potentials (EPs), is of high relevance for an objective electrophysiological assessment. The aim of this work is to detect weak EPs from highly contaminated signal traces. In principle this can be done using methods of spatiotemporal signal processing, which simultaneously increase the weak SNR (signal-to-noise ratio). However, methods based on any a priori knowledge of spatial or temporal properties as well as the propagation speed and direction are not applicable. Models with adjustable signal properties similar to real cortical activity are necessary for the development and evaluation of new methods of spatiotemporal signal processing. A model is needed which can be used in forward- and inverse-projection calculations. This study aims to develop a signal generator of the background EEG activity with embedded EPs of fully adjustable signal parameters. The study also compares the results of modeled signal analysis by known methods for signal decomposition, SVD (singular value decomposition) and ICA (independent component analysis).     

Evolution of the microstructure in the hot rolling process

A thermomechanical finite-element model of flat rolling is coupled with closed form equations describing the process of recrystallization and is applied to study hot rolling of low carbon steel strips. Formulae for the recrystallized grain diameters, developed by various authors, are considered. Calculated diameters of the grains are compared with the results of the measurements carried out after experimental hot rolling of the carbon steel samples. Evaluating the accuracy of the calculations, using each of the expressions for the diameter of the recrystallized austenite grains, indicates that the relation of Roberts is closest to the measurements.     

Interfacial activity of 4-alkylphenylamines and the rate of palladium(II) extraction

Interfacial tension isotherms were determined in hydrocarbon-water systems for 4-alkylphenylamines containing from 6 to 16 carbon atoms in their alkyl chains, and the surface excess isotherms were computed and interpreted using various adsorption isotherms. Palladium(II) was extracted with 4-alkylphenylamines from 3 M HCI solutions. The maximum extraction rate of palladium(II) is observed for 4-decyl- and 4-dodecylphenylamines which exhibit good interfacial activity. Compounds soluble in the aqueous phase (4-hexylphenylamine) or in toluene (4-hexadecylphenylamine) extract palladium(II) slower than 4-decyl- and 4-dodecyl- phenylamines.     

Fields of strains around the inclusion of second phase in a uniform matrix undergoing plastic deformation

This paper focuses on the problem of the evaluation of strains around the inclusions of various shapes and properties located in the uniform matrix undergoing large plastic deformations. The analysis is performed using the rigid-plastic finite-element approach. The uniform plane-strain deformation field is simulated by an introduction of zero friction forces into the program for the compression process. An assumption that the die is wider than the sample allows to simulate ideally uniform flow of metal. Several shapes of the inclusions are investigated, but the results for three most common shapes of the particle's cross-section are presented in the paper. They are: square with the sides parallel to the main directions, square with the sides inclined under an angle of 45° to the main directions and round.     

Electrochemical deposition of poly(o-anisidine) and polypyrrole at octadecanethiol coated gold electrodes

The o-anisidine and pyrrole have been polymerized by the electrochemical oxidation of monomers on gold electrodes, covered with self-assembled monolayers. The obtained polymer–monolayer systems have been investigated by cyclic voltammetry in aqueous supporting electrolyte solutions containing K₄Fe(CN)₆ and Ru(NH₃)₆Cl₃. The deposition of conducting polymers strongly depends on the integrity of a monolayer. In the case of a large number of SAM defects, the polymerization of o-anisidine and pyrrole leads to the formation of nuclei of the conducting polymer in the insulating matrix of the thiol monolayer. When the polymer is in the conducting (oxidized) form, the nuclei act as an array of microelectrodes. The polarogram-shaped voltammograms obtained for K₄Fe(CN)₆ confirm the hemispherical diffusion of redox species to the polymer nuclei. When the polymer is in the non-conducting (reduced) form, the polymer–octadecanethiol layer blocks the redox processes on the electrode. The exponential-type CV curves observed for Ru(NH₃)₆Cl₃, when the polymer is in its non-conducting state, can be assigned to the tunnelling of electrons through the passivating layer. The use of monolayers with a low number of defects influences the mechanism of polymer growth. Thus, the polypyrrole grows on the layer of thiols, and the poly(o-anisidine) forms polymer nuclei.     

Modelling water cooling of steel strip during hot rolling

Several tests of water cooling of steel samples are presented in the paper. The water spray and quenching conditions are considered. The temperature variations during the tests are monitored using the thermocouples embedded in the side of the samples. The experimental time – temperature profiles are compared with the results of calculations based on the finite element model. Comparison of the theoretical and experimental results allowed to suggest heat transfer coefficients of 10000 W/m²K for water in quenching, 6000 W/m²K for the top surface during water spray cooling and 4000 W/m²K for the bottom surface during water spray cooling.     

Problem of stress and strain concentration in the entry and exit planes in the drawing process

The paper discusses the problem of stress and strain concentration in the entry and exit planes during the drawing process. Earlier investigations carried out by Pierlin, Pawelski and Armstroff as well as Chen and Kobayashi's finite element analysis are reviewed. Authors’ calculations based on the rigid-plastic finite element approach are compared with experimental and theoretical results published by Pawelski and Armstroff. Solution for rigid-plastic material behaviour confirmed the die pressure increase in the entry and exit zones questioning Pierlin's suggestion that the elastic strains are responsible for pressure concentrations. Analysis of the strain rate distribution led to the presumption that pressure increase is due to the strain rate concentrations in the areas close to the entry and exit zones.     

Hemostasis in fatty liver

A controlled, double-blind trial on 42 children showed that a dentrifrice containing 0,25% fluorine clearly prevented caries when used continuously for 2 years. This effects was greater than that of a similar toothpaste containing fluorine. Tolerance was excellent.