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1

Do we still need a laboratory to study advanced oxidation processes? A review of the modelling of radical reactions used for water treatment

Wacławek Stanisław

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 1

11--28

EN

Environmental pollution due to humankind’s often irresponsible actions has become a serious concern in the last few decades. Numerous contaminants are anthropogenically produced and are being transformed in ecological systems, which creates pollutants with unknown chemical properties and toxicity. Such chemical pathways are usually examined in the laboratory, where hours are often needed to perform proper kinetic experiments and analytical procedures. Due to increased computing power, it becomes easier to use quantum chemistry computation approaches (QCC) for predicting reaction pathways, kinetics, and regioselectivity. This review paper presents QCC for describing the oxidative degradation of contaminants by advanced oxidation processes (AOP, i.e., techniques utilizing •OH for degradation of pollutants). Regioselectivity was discussed based on the Acid Blue 129 compound. Moreover, the forecasting of the mechanism of hydroxyl radical reaction with organic pollutants and the techniques of prediction of degradation kinetics was discussed. The reactions of •OH in various aqueous systems (explicit and implicit solvation) with water matrix constituents were reviewed. For example, possible singlet oxygen formation routes in the AOP systems were proposed. Furthermore, quantum chemical computation was shown to be an excellent tool for solving the controversies present in the field of environmental chemistry, such as the Fenton reaction debate [main species were determined to be: •OH < pH = 2.2 < oxoiron(IV)]. An ongoing discussion on such processes concerning similar reactions, e.g., associated with sulphate radical-based advanced oxidation processes (SR-AOP), could, in the future, be enriched by similar means. It can be concluded that, with the rapid growth of computational power, QCC can replace most of the experimental investigations related to the pollutant’s remediation in the future; at the same time, experiments could be pushed aside for quality assessment only.

2

Źródła antropogenicznych anomalii grawitacyjnych i ich znaczenie

Bednarek Stanisław

Przegląd Geodezyjny

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2020

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R. 92, nr 2

15--19

PL

Artykuł przedstawia zarys problemu antropogenicznych anomalii grawitacyjnych. W odróżnieniu od innych prac, koncentrujących się głównie na anomaliach pochodzenia górniczego, podjęto w nim próbę całościowego ujęcia tematu. W początkowej części artykułu zwrócono uwagę na problemy związane z wyznaczeniem przyspieszenia siły ciężkości oraz znaczenie tej wielkości dla konstrukcji geoidy i dokładności pomiarów geodezyjnych. Zdefiniowano antropogeniczną anomalię grawitacyjną i podano opracowaną przez autora systematyczną klasyfikację jej źródeł. Sformułowano uproszczone modele obliczeniowe dla charakterystycznych typów źródeł. Używając tych modeli, oszacowano wartości anomalii grawitacyjnych, powodowanych przez wymienione w klasyfikacji, reprezentatywne przykłady źródeł i przedyskutowano ich znaczenie.

EN

This article presents the outline of the anthropogenic gravity anomalies problem. In contrast to other papers concerning mining-related anomalies, here a holistic approach to the subject was attempted. In the introductory part of the article, the attention is given to the problems with determination of the gravity acceleration, and the importance of this estimation to the geoid construction and accuracy of measurements in land surveying. An anthropogenic gravity anomaly was defined and a systematic classification of its sources was developed and given by the author. Simplified computational models for the characteristic source types were formulated. Using those models, the values of gravity anomalies were estimated. The anomalies are caused by enumerated in the classification representative examples of sources and their significance was discussed.

3

Modelling thermal properties of large LED modules

Ptak Przemysław, Górecki Krzysztof, Dziurdzia Barbara

Materials Science Poland

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2019

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Vol. 37, No. 4

628--638

EN

In this paper a problem of modelling thermal properties of large LED modules is considered. The compact thermal model of such modules is proposed. The form of this model is presented and a method of parameters estimation is described. The practical usefulness of this model is verified experimentally by comparing the results of calculations and measurements of internal temperature of selected LEDs included in LED modules. The modules were fabricated by Fideltronic, Poland and measurements of temperature distribution on the surface of the modules at selected variants of power dissipation were performed at the Gdynia Maritime University. Good agreement between the results of measurements and modelling was obtained.

4

Modelowanie właściwości elektrolizera w programie SPICE

Górecki P., Górecki K., Zarębski J.

Elektronika : konstrukcje, technologie, zastosowania

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2017

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Vol. 58, nr 10

15--18

PL

W pracy zaproponowano model obwodowy elektrolizera w formie dedykowanej dla programu SPICE. Model ten uwzględnia zarówno właściwości statyczne, jak i dynamiczne rozważanego urządzenia i jest przeznaczony do optymalizacji parametrów sygnału zasilającego ten elektrolizer. Przedstawiono postać opracowanego modelu opisującego właściwości elektryczne elektrolizera oraz pokazano wyniki weryfikacji eksperymentalnej poprawności tego modelu. Wykorzystując przedstawiony model przeprowadzono symulacje komputerowe ilustrujące wpływ częstotliwości sygnału zasilającego elektrolizer oraz stężenia roztworu na wydajność i sprawność energetyczną procesu elektrolizy. Wybrane wyniki obliczeń zweryfikowano doświadczalnie.

EN

In the paper the network model of the electrolyser in the form dedicated for SPICE software is proposed. This model takes into account both static and dynamic proprieties of the considered device and it is devoted to the optimization of parameters of the signal feeding this electrolyser. The form of the worked out model describing electrical properties of the electrolyser is presented and some results of the experimental verification of the correctness of this model are shown. Using the presented model some computer simulations illustrating the influence of the frequency of the signal feeding the electrolyser and of the concentetion of the solution on the productivity and the efficiency of the electrolysis process are performed. Selected results of the calculations are compared with results of measurements.

5

Obliczenia sieci ciepłowniczych

Lichota J., Grabowski B.

Rynek Energii

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2011

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nr 4

64-70

PL

Artykuł jest kontynuacją poprzedniego pod tym samym tytułem [7]. Pokazano w nim zastosowanie algorytmu obliczeń wodnych sieci ciepłowniczych do rozwiązania ważnych problemów w sieciach ciepłowniczych na przykładach: zmiany oporności odcinka sieci, awarii odcinka, awarii węzła cieplnego, wprowadzenia nowej przepompowni, nierównowagi strumieni w źródle i u odbiorców, wprowadzenia nowego źródła, wzrostu i spadku zapotrzebowania przez odbiorców.

EN

This paper shows examples of utilization of algorithm designed for hydraulic computations presented in part I under same title [9]. Examples are important for modeling of different applications in district heating like increase of pipe resistance (point 1.2), damage of pipe (point 1.3), damage of heat node (point 1.4), a new pump location in a network (point 1.5), non-equlibrium of water mass flow from source and at customers (point 1.6), a new heat source location in network (point 1.7) and reduction of mass flow from existing source (point 1.8). Example 1.1 describes assumed basic geometry of network and proposed algorithm of initial mass flow computing. Setting initial mass flow is not trivial problem because number of equations are less than number of variables. The only condition, which should be meet to obtain mass flows in network from non-linear algebraic set of equations is such, that initial mass flow have to fulfill that set. In contradiction to Moore-Pennrose solving a problem by giving as an answer "best" result in sense of least squares proposed algorithm is very simple and requires less computations.

6

Transients of electrical and mechanical quantities of a brushless DC motor - computations, measurements

Ciurys M., Dudzikowski I.

Archives of Electrical Engineering

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2011

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Vol. 60, nr 1

23-34

EN

The paper presents a method of computing electrical and mechanical variables of BLDC motors. It takes into account electrical, magnetic and mechanical phenomena in the power supply-converter-BLDC motor-load machine system. The solution to the problem is the so-called circuit-field method. The results determined with the use of time stepping finite element method were used as the parameters of equations of the developed mathematical model. Losses in the motor, losses in transistors and diodes of the converter as well as the actual back EMF waveforms, variable moment of inertia and variable load torque are accounted for. The designed laboratory stand and the test results are presented in the paper. The experimental verification shows the correctness of the developed method, algorithm and program. The developed computational method is universal with respect to different electromechanical systems with cylindrical BLDC motors. It can be applied to electromechanical systems with BLDC motors operating at constant but also variable load torque and moment of inertia.

7

Computation of plane structures eigenfrequencies by hybrid finite element method using Trefftz functions

Bozduganova V., Todorov M.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2010

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z. 80 [274]

25-32

EN

A hybrid stress method for eigenfrequencies analysis is developed using a plane rectangular hybrid element. Complex Trefftz functions which are solutions of elastostatic problem are used. By the complementary energy variational equation a relationship between the stress parameters and the nodal displacements is obtained. The Lagrange's variational equation for the dynamic case gives an expression for computation of eigenfrequencies.

8

Obliczenia sieci ciepłowniczych

Lichota J.

Rynek Energii

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2010

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nr 6

71-76

PL

Artykuł jest poświęcony sposobowi obliczeń sieci ciepłowniczych. Omówiono algorytm obliczeń zaproponowany przez Chasiliewa i Mierenkowa. Osiągnięciem autora jest skrócenie zarówno wyprowadzenia jak i samego algorytmu oraz pokazanie nowych rezultatów dla problemu wartości początkowych strumieni masy wody w sieci ciepłowniczej. Za-proponowano nową metodę obliczania wartości początkowej strumienia masy wody w sieci, która szczegółowo będzie omówiona w kolejnym artykule. Proponowany algorytm może zostać zastosowany w oprogramowaniu do symulacji i wymiarowania sieci ciepłowniczych.

EN

This paper shows proof, implementation and algorithm designed for computations of hydraulic conditions in district heating networks. Mathematical model of network is described by matrix equations (2). Algo-rithm of solution is shown in Fig. 1 and m-file in appendix.

9

Experimental verification of two-parametic models of fatigue characteristics by using the tests of S55J0 steel as an example

Ligaj B., Szala G.

Polish Maritime Research

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2010

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nr 1

39-50

EN

This paper presents experimental verification of models of two-parametric fatigue characteristics N(óa , óm ) on the basis of results of fatigue tests of specimens made of S355J0 steel. On the basis of comparative analysis of results of computations and fatigue life tests of the specimens, performed under constant amplitude sinusoidal loads of different cycle asymmetry ratios, the most versatile models were distinguished. The tests in question were carried out in the high-cycle fatigue range.

10

Insertion Loss of Spiral Ducts - Measurements and Computations

Łapka W.

Archives of Acoustics

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2009

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Vol. 34, No. 4

537-545

EN

This work presents measured and computed characteristics of insertion loss (IL) of spiral ducts. Numerical and experimental models of spiral ducts have been investigated. For the numerical modeling, a three dimensional model computed by the use of a finite element method in a COMSOL Multiphysics computer application has been used. For the experimental modeling, there has been made a spiral duct model by using a three dimensional rapid prototyping technique. An acoustic system with a round silencer has been ivestigated, and the spiral duct has been inserted at the inlet. IL is considered in this paper as the difference between the sound pressure level (SPL) [dB] probed at only one outlet point of the acoustic system without and with an acoustical filter (spiral duct), respectively. The results of measured and computed IL of spiral ducts presented in this paper confirm the fact that this newly discovered technical solution for attenuating sound in ducted systems has an applicable potential. There are visible small discrepancies between the measurements and computations. The results can differ due to the non ideal dimensions of the experimental model and the non ideal inlet and outlet surroundings of the experimental acoustic system. However, the IL characteristics of the computed model is almost wholly covered by the IL characteristics of the measured model.

11

Możliwości ograniczenia strat tarcia w łożyskach mechanizmu korbowego

Krzymień A., Krzymień P.

Czasopismo Techniczne. Mechanika

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2008

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R. 105, z. 7-M

265-273

PL

Podczas eksploatacji pojazdu napędzanego silnikiem spalinowym zależy nam na możliwie niewielkim zużyciu paliwa i ograniczeniu emisji toksycznych składników spalin. Jedną z metod jest minimalizacja strat tarcia m.in. w węzłach łożyskowych mechanizmu korbowego, brana pod uwagę już na etapie projektowania, jak i podczas eksploatacji silnika. W artykule przedstawiono wyniki obliczeń strat tarcia łożyska głównego silnika samochodowego oraz propozycję ich zmniejszenia na podstawie analizy wybranych czynników konstrukcyjnych i eksploatacyjnych.

EN

Least possible fuel consumption and emissions are the goals we try to achieve during engine operation. One of the methods leading to this target is the minimization of friction losses, among others those at crank mechanism bearings, taken into consideration at the stage of engine design and during engine operation as well. This paper presents some results of friction losses calculations for automotive engine main bearings and a proposal how to reduce them as the outcome of a thorough analysis of selected constructional and operational factors.

12

Rozrusznik samochodowy z bezszczotkowym silnikiem prądu stałego

Ciurys M., Dudzikowski I.

Elektrotechnika i Elektronika

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2006

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T. 25, z. 2

129-132

PL

Opracowano model matematyczny, algorytm i program obliczeń przebiegów czasowych wielkości elektrycznych i mechanicznych w układzie: akumulator - rozrusznik samochodowy z bezszczotkowym silnikiem prądu stałego (BLDC) - silnik spalinowy. Opracowany model matematyczny, algorytm i program obliczeń uwzględniają, m.in.: zmienność momentu bezwładności układu korbowego silnika spalinowego, zmienność momentu kompresji i dekompresji gazów w cylindrach oraz zależność momentu tarcia silnika spalinowego od prędkości chwilowej wału korbowego. Obliczono przebiegi czasowe wielkości elektrycznych i mechanicznych w analizowanym układzie.

EN

A mathematical model, algorithm and program for calculations of electrical and mechanical quantities transients in the system: accumulator — starter with brushless direct current motor - combustion engine were developed (Figs 1, 2, 3). The developed mathematical model, computational algorithm and program take account of the combustion engine crankshaft moment of inertia variations as well as the variations of both the compression and decompression torque in the cylinders and the combustion engine friction torque dependence on the instantaneous crankshaft speed. Transients of electrical and mechanical quantities in the analysed system were calculated (Figs 4, 5).

13

Vibrational properties and thermochemistry from first principles

Wolf W., Sticht J., Mavromaras A., Leblanc B., Saxe P., Wimmer E.

Materials Science Poland

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2005

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Vol. 23, No. 2

365--373

EN

The simulation of vibrational properties and finite temperature effects based on ab initio calculation of phonons within the direct approach is discussed. The implementation of the approach within an automated computational framework is outlined, and applications in rather diverse fields are demonstrated: phonon dispersion of GaAs, Kohn anomaly in Niobium, rattling modes in thermoelectric skutterudites, reaction enthalpies and formation enthalpies of hydrides and hydrogen storage materials, phase transformations, surface reconstruction of Si( 111), and adsorption of CO molecules on a Ni( 001) surface.

14

The growing importance of computations in materials science. Current capabilities and perspectives

Wimmer E.

Materials Science Poland

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2005

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Vol. 23, No. 2

325--345

EN

Materials scientists are facing unprecedented challenges in many areas, such as energy conversion and storage, microelectronics, telecommunication, display technologies, catalysis, and structural materials. Experimental methods generate increasing amounts of data. New computational methods, high-performance computer hardware, and powerful software environments are evolving rapidly. As a result, the importance of computational materials science is growing. The following cases illustrate the current capabilities: computed thermochemical and mechanical properties of metal hydrides show trends in the heats of formation and the hydrogen-induced softening of elastic moduli; a study of the effect of impurities on the strength of a Ni grain boundary reveals hydrogen as an embrittler and boron as a strengthener; ab initio phonon calculations for hydrogen impurities in aluminum show a temperature-dependent site - preference; the screened-exchange approach predicts accurate energy band gaps of semiconductors; a computational screening of hydro-desulphurization catalysts points to new combinations. The major current challenges for computational materials science include more accurate total energies, unified methods to deal with multi-phase systems, e. g., solid/liquid, novel approaches to determine complex kinetic processes, and novel concepts to bridge the atomistic and the macroscopic scales.