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1

A discrete-time queueing system with changes in the vacation times

Atencia I.

International Journal of Applied Mathematics and Computer Science

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2016

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Vol. 26, no. 2

379--390

EN

This paper considers a discrete-time queueing system in which an arriving customer can decide to follow a last come first served (LCFS) service discipline or to become a negative customer that eliminates the one at service, if any. After service completion, the server can opt for a vacation time or it can remain on duty. Changes in the vacation times as well as their associated distribution are thoroughly studied. An extensive analysis of the system is carried out and, using a probability generating function approach, steady-state performance measures such as the first moments of the busy period of the queue content and of customers delay are obtained. Finally, some numerical examples to show the influence of the parameters on several performance characteristics are given.

2

Zawartość trytu i skład izotopowy tlenu w płytkich wodach podziemnych w punktach badawczych krajowej sieci monitoringu

Nowicki Z., Leśniak P.M., Wilamowski A.

Przegląd Geologiczny

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2015

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Vol. 63, nr 10/2

976--980

EN

The points of the national network of groundwater monitoring comprise a stable benchmarks in quality and quantity monitoring. The obtained data (tritium and δ18O) are important for understanding the groundwater cycling and are indirect indicators of aquifer vulnerability to anthropogenic pollution. The goal of this paper is to present the relation of the tritium content and delta value of stable isotopes of oxygen against the groundwater sampling depth in 2004–2012. It is demonstrated that the remains of “nuclear” tritium concentration is still present in groundwater as a tritium peak at depths around 30 m. Determination of dynamics of recharge in groundwater bodies, based on national network observation points is associated to the estimation of the groundwater residence time in aquifers and remains one the vital problem of hydrogeology.

3

Badanie kinetyki mielenia węgla energetycznego metodą atomów znaczonych

Tora B.

Przegląd Górniczy

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2012

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T. 68, nr 3

104--109

PL

Artykuł przedstawia wyniki oznaczenia czasów przebywania wybranych klas ziarnowych węgla energetycznego w młynie za pomocą metody atomów znaczonych. Wykazano, że czas przebywania węgla w młynach pierścieniowo-kulowych z wewnętrznymi zawrotami jest wprost proporcjonalny do wielkości ziarna nadawy. Wykazano możliwość wykorzystania rezultatów uzyskanych w wyniku badania procesu mielenia za pomocą metody znaczników promieniotwórczych dla określenie kinetyki rozdrobnienia węgla w młynie. Wyznaczone modele kinetyki mielenia klas ziarnowych węgla są podstawą optymalizacji przemysłowego procesu mielenia węgla w energetyce zawodowej.

EN

The article presents the results of determination of the residence time of selected size grades of power coal in the grinding mill by means of the labelled atom method. It has been shown that the residence time of coal in ring-ball mills is directly proportional to the size of feed grain. The possibility has been pointed out to use the results obtained in consequence of the grinding process testing by means of the radioactive marker method in order to determine the coal size reduction kinetics in the mill. The determined models of grinding kinetics of coal grain classes are the basis of optimization of the industrial coal grinding process in the professional power industry.

4

Methods and results of groundwater vulnerability evaluation to contamination in the Kampinoski National Park, central Poland

Krogulec E.

Acta Geologica Polonica

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2006

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Vol. 56, no. 3

349-359

EN

Aquifer vulnerability maps are valuable tools for communicating concerns about the level of groundwater pollution hazard to local landuse planners and to the general public. Groundwater vulnerability to contamination in the Kampinoski National Park (KNP) area in central Poland was evaluated as a basis for developing appropriate protection strategy for the groundwater resources and management in recreation areas located near Warsaw. Assessment was accomplished using U.S. EPA DRASTIC and the residence time in the unsaturated zone of a conservative pollutant. The final DRASTIC values have been grouped into medium (37 % of area) and medium high (52 %) intrinsic vulnerability categories. The residence time in the unsaturated zone is classified in 11 intervals, ranging from 30 days to 30 years, but nearly 75 % of the study area is characterized by intervals from 1 to 3 years.

5

Czas przebywania kryształów w krystalizatorze fluidalnym z idealną klasyfikacją

Wójcik J.

Inżynieria i Aparatura Chemiczna

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2004

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Nr 4-5

50-51

PL

Na podstawie artykułu [1] w niniejszej pracy przedstawiono wyprowadzenie wzorów na określenie czasu przebywania kryształów oraz całkowitego czasu przebywania dla procesu krystalizacji fluidalnej w przypadku idealnej klasyfikacji.

EN

On the basis of [1] a derivation of formulae for the crystals residence time and overall residence time within the fluidised-bed crystallizer with ideal classification is presented.

6

The influence of residence time on the crystallization of barium sulphate in the process of barium ions precipitation by means of crystalline ammonium sulphate addition

Matynia A., Wlazło P., Koralewska J.

Polish Journal of Applied Chemistry

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2001

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Vol. 45, nr 3-4

91-107

EN

Measurement results of barium sulphate reaction crystallization kinetics are presented. Experiments were carried out in the crystallizer with an internal circulation of suspension. The crystallizer was continuously fed with barium chloride solution (of concentration 24.0 mass %) and stoichiometrically crystalline ammonium sulphate. The rates of BaSO4 nucleation and crystal growth were estimated from crystal size distribution according to calculation procedure for the MSMPR crystallizer. Research results may be utilized in the technology of post quenching salts processing.