Optimisation and experimental verification of a dust-removal beater for the electrodes of electrostatic precipitators

The results of research into changes in vibrations of collecting electrodes are presented in the paper. The changes come from the optimisation of geometric and dynamic parameters of the shaking down system inelectrostatic precipitators (ESP). The computational verification was carried out using the finite element method on the MSC NASTRAN package. Vibrations and accelerations of the collecting electrodes were measured. The results were used in the comparative analysis and the analysis of spectral density of acceleration power. The paper shows how calculating methods completed by measurements allow us to solve important and sophisticated practical problem.     

Time-Domain Methods for Solving Problems of Linear Acoustics

This paper describes a class of high-order Taylor-Galerkin methods for solving problems of linear acoustics characterized by the classical (scalar) wave equation. The methods provide high-order temporal accuracy and unconditional stability on arbitrary nonuniform finite element meshes of varying element sizes and shape functions.     

Hydrodenitrogenation of indole over Mo2C catalyst: Insights into mechanistic events through DFT modeling

The molecular reaction mechanism of hydrodenitrogenation of indole was studied using density-functional theory calculations of the adsorbed o-ethylaniline surrounded by mobile hydrogen atoms. It was found that the hydrogenation of o-ethylaniline occurs through two steps: consisting in redistribution of the π electron density to form multiple partial MoC(ring) bonds with the surface upon adsorption, and a subsequent hydrogen attack directed on the aromatic ring or the amine group. The direction of the hydrogen attack and the associated energy barriers determine the rate constants of the early (DDN, direct denitrogenation) and late (HYD, hydrogenation) nitrogen removal steps, and thus rules the selectivity of indole hydrodenitrogenation to ethylcyclohexane or ethylbenzene.     

Impact of lead/zinc ore mining on groundwater quality in Trzebionka mine (southern Poland)

The intensive mining activity carried out by “Trzebionka” zinc-lead mine causes changes in the hydrodynamic regime of the triassic aquifer as well as essential changes in the chemical composition of the groundwater. The mine water, in comparison with groundwaters collected directly from fractures and Karstic channels and with groundwaters pumped out from wells situated in Chrzanow region, is characterized by higher contents of almost all major dissolved constituents as, well as, many trace elements. Hydrogeochemical background of triassic carbonate series aquifer has been elaborated. Largest anomalies in extent of almost all elements have occurred in area of the “Trzebionka” mine. In this water general trend of increase of pH, total dissolved solids and SO₄ ²⁻ concentration with simultaneous trends of decrease of Zn²⁺ and Pb²⁺ concentrations have been noticed. Water pumped out from the mine in spite of its low quality, is utilized in about 80% as potable water after undergoing complicated treatment.     

Role of O-acetylhomoserine sulfhydrylase in sulfur amino acid synthesis in various yeasts

Mutants defective in O-acetylhomoserine sulfhydrylase (OAH-SHLase) were obtained in five yeast strains representative of different yeast genera: Saccharomyces cerevisiae, Kluyveromyces lactis, Yarrowia lipolytica, Schizosaccharomyces pombe and Trichosporon cutaneum. In vitro, in all five strains, the enzyme also had O-acetylserine (OAS) sulfhydrylase activity so it is a ‘bifunctional’ OAH/OAS-SHLase (Yamagata, 1989). The enzyme was only found to be essential in S. cerevisiae (OAH SHLase-negative mutants are auxotrophs). Its impairment in K. lactis caused a slower growth rate and a decrease of the sulfur amino acid pool. In T. cutaneum only the pool was affected whereas in Y. lipolytica and S. pombe the lesion caused no change in the growth rate nor in the pool. In all strains where OAH SHLase-negative mutants were prototrophs, a monofunctional OAS sulfhydrylase was detected. The results indicate that OAH SHLase may play different physiological roles in various yeasts.     

Determination of the glass transition temperature of poly(styrene-co-divinylbenzene) by inverse gas chromatography

Inverse gas chromatography (i.g.c.) was used to characterize the supermolecular structure of modified, moderately crosslinked poly(styrene-co-divinylbenzene) (5–20 wt%) and to determine the interactions with normal alcohols (C₁C₆). For all copolymers a decrease of retention time with increasing molecular weight of alcohols from C₁ to C₃ followed by an increase for C₄ to C₆ alcohols was observed. It was found that with propanol or butanol the measured T_g values were close to those measured by d.s.c. The T_g values for poly(styrene-co-divinylbenzene) containing 5, 10 and 20 wt% divinylbenzene were: 102°C, 116°C and 133°C respectively. The highest alcohols (C₅ and C₆) acted as plasticizers and reduced the apparent T_g value. The relationship between the isosteric heat of adsorption and the number of carbon atoms in the alcohols was nonlinear with a minimum corresponding to butanol.     

Client-specific A-stack model for adult face verification across aging

The problem of time validity of biometric models has received only a marginal attention from researchers. In this paper, we propose to manage the aging influence on the adult face verification system by an A-stack age modeling technique, which uses the age as a class-independent metadata quality measure together with scores from a single or multiple baseline classifiers, in order to obtain better face verification performance. This allows for improved long-term class separation by introducing a dynamically changing decision boundary across the age progression in the scores-age space using a short-term enrollment model. This new method, based on the concept of classifier stacking and age-aware decision boundary, compares favorably with the conventional face verification approach, which uses age-independent decision threshold calculated only in the score space at the time of enrollment. Our experiments on the YouTube and MORPH data show that the use of the proposed approach allows for improving the identification accuracy as opposed to the baseline classifier.     

Application of electron paramagnetic resonance (EPR) spectroscopy for control of irradiated food

Four groups of foodstuffs were irradiated in a ⁶⁰Co source with doses from 0.3 to 10kGy and subsequently measured by EPR spectrometry at room temperature in air: (1) poultry bones and fins, scales and bones of carp. (2) seeds of selected fruits, (3) dehydrated mushrooms, and (4) a selected set of spices and herbs. Qualitative and, in some cases, quantitative data related to the absorbed dose of radiation were collected. In the irradiated bones from poultry and carp an asymmetric singlet (g_I = 2.0030, g_II =1.9973; ΔH_pp = 0.85 mT) was detected which was stable at room temperature and was similar to that previously found in irradiated mammalian bones. Another stable EPR signal (g₀ = 2.0024, ΔH_pp = 0.56 mT) was found in the fins and scales of carp which was about five times more intense in fins than in scales. In pips of pears irradiated with a dose of 3 kGy. a signal which was about twice as intense as the endogenous signal was recorded. A multicomponent EPR signal derived from the stones of dates differed from the endogenous signal even when a low dose (0-5 kGy) was applied. A multicomponent EPR signal is also observed in dried mushrooms irradiated with a dose of 3 kGy. In white mustard, paprika and chilli no native EPR signal exists and a radiation-induced stable EPR signal can still be observed after a period of 3 months. The radiation-induced EPR signal in black pepper was highly sensitive to moisture and disappeared, yet the native signal survived. The pilot experiments performed with irradiated stones of cherries, plums, lemons, apple pips, raspberries, cranberries, red currants, blackcurrants, gooseberries and tomatoes showed the induction of short-lived EPR signals of no practical use for the control of food irradiation.