New approach to a problem of heat transfer with chemical reaction in a cylinder of finite dimensions

The three-dimension heat transfer problem of non-isothermal decomposition for a solid cylindrical particle was studied. The non-stationary thermo-chemical process with high activation energy in the particle was described by the system of two non-linear integro-differential equations over the temperature and material density. The solution of these equations was obtained by the semi-analytical method. The influence of chemical reaction parameters on the temperature field inside the cylinder was established. The numerical simulation was carried out for a solid particle heated with linearly increasing temperature from 30 to 700 °C. Special attention was paid to the spatial and time dependent distributions of the temperature field for different heating rates. This approach can be applied for kinetic parameter estimation of thermogravimetric measurements.     

REVIEW OF THIN-LAYER DRYING AND WETTING EQUATIONS

Thin-layer equations contribute to the understanding of the heat and mass transfer phenomena in agricultural products and computer simulations for designing new and improving existing commercial drying processes. Many different equations have been developed to represent thin-layer drying behaviour of the grains. Many thin-layer drying and rewetting equations are reviewed and discussed. Some suggestions for future coordinated research work arc given.     

Selective catalytic reduction of NO by alcohols on Co- and Fe-Siβ catalysts

Co–Siβ and Fe–Siβ catalysts prepared by a two-step post-synthesis method were characterised by EPR, diffuse reflectance UV–vis, XRD and N₂-physisorption. Iron and cobalt ions are present as isolated lattice tetrahedral Co^II and Fe^III species for low metal contents (0.7 and 0.9 wt.%, respectively). For higher iron content, FeO_x oligomers appear. Zeolites with isolated Co^II and Fe^III species are active in selective catalytic reduction of NO with ethanol. On FeO_x oligomers the oxidation of NO to NO₂ starts to dominate in the selective catalytic reduction of NO with ethanol at the temperatures higher than 700 K.     

Finding all the DC solutions of a certain class of piecewise-linear circuits

The problem of finding all the DC solutions of a certain class of piecewise-linear electronic circuits containing locally passive and locally active one-ports is considered in this paper. An effective method enabling us to locate the solutions is developed. The method constitutes the crucial point of an algorithm based on the idea of successive contraction, division, and elimination that is capable of determining all the solutions. Several numerical examples are given, and some comparison analyses are performed confirming the usefulness of the proposed approach.This work was supported by the State Committee for Scientific Research (KBN) under grant 8T11B0911.     

Neural networks for constrained optimization problems

This paper is concerned with utilizing neural networks and analogue circuits to solve constrained optimization problems. We propose a novel neural network architecture for solving a class of non-linear programming problems. the proposed neural network is then used, and if necessary modified, to solve minimum norm problems subject to linear constraints. Minimum norm problems have many applications in various areas, but we focus on their applications to the control of discrete dynamic processes. the applicability of the proposed neural network is demonstrated on numerical examples.     

Reduced-order observer-based decentralised control of non-linear interconnected systems

The output feedback-based asymptotic stabilisation problem for a class of non-linear interconnected systems is considered, where the non-linear interconnections between subsystems satisfy quadratic constraints. A novel decentralised dynamic output feedback control strategy involving local projection operator-based reduced-order observers is proposed. This decentralised controller is characterised by the separation property. Two easily verifiable conditions that guarantee the asymptotic stability of the closed-loop system driven by the proposed decentralised controller are given. The effectiveness of the developed decentralised control strategy is illustrated with a numerical example and simulations.     

Yield and maintenance coefficients in S. cerevisiae cultures

Precise determination of yields deduced from measurements of metabolic rates needs an understanding of the physiology and energetics of growth of microorganisms. The linear growth equation derived from the simplified picture of microbial metabolism is generally accepted. However, the significance of the yields it gives is less well understood. The analysis of the theoretical and real observed and true yield coefficients for partly aerobic and anaerobic growth of S. cerevisiae is presented in this study. In the calculations of yields and maintenance coefficients, the pseudoconstants Y, P/O were used. A set of limitations imposed on true yields in the linear growth equation is established and the significance of the yields is also discussed. The experimental runs were performed in a laboratory-scale bioreactor (1·5 dm³ of operating capacity). The yeast Saccharomyces cerevisiae hybrid G-67 was cultured in synthetic Reader medium containing sucrose as the main carbon and energy source. The comparison between experimentally obtained yield coefficients relative to cell growth and ethanol formation and the real theoretical values is presented. The maintenance coefficients calculated for anaerobic and respiro-fermentative processes are 0·14 C-mole ATP (C-mole DM h)⁻¹. © 1998 SCI     

The reactivity of titanium–vanadium containing groups in the synthesis of two-component monolayers on silica surfaces

The coating of silica surfaces with two-component VOCl₃ and TiCl₄ monolayers was studied with respect to the composition of the products and the kinetics of interaction. The titanium and vanadium-containing groups were found to be able to replace each other equivalently. Surface sites were found to determine reactivity, as were lateral interactions in the monolayer. The results found the presence of two kinds of active center; with the estimated ratio of such groups correlating with data from chemical analyses of the concentrations of groups covalently linked to the surface by different numbers of bonds.     

Germicidal Properties of Ozonated Sunflower Oil

The aim of this work was to establish the minimal inhibition concentration (MIC) of ozonated sunflower oil for various microorganisms. To determine the influence of the ozonated medium on the growth of bacteria Bacillus subtilis, Escherichia coli and yeast Candida albicans the Petri dish method was used. Chemical and physical properties of ozonated sunflower oil were additionally studied. Microbiological studies proved that these microbes have various sensibility against ozonated oil. The most resistant are gram-negative bacteria E. coli and the yeast C. albicans. Gram-positive bacteria, B. subtilis turned out to be less resistant, because no growth was observed for preparation with an ozone dose of 200 mgO₃/g oil.