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1

The formation regularities of aerosols resulting from arc welding of main gas pipelines

Semchuk Jaroslav, Vasyliv Nataliia, Kryvenko Galyna M., Lialiuk-Viter Halyna, Hrytsuliak Halyna Myhaylovna, Kotsyubynsky Andrij, Voloshyn Yurii

Nafta-Gaz

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2025

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R. 81, nr 8

530--537

EN

The oil and gas industry is characterized by the presence and operation of various high-risk facilities, which contribute to occupational injuries and diseases, as well as environmental pollution. Among these, pipeline systems – particularly main gas pipelines – are prominent. The purpose of this research is to study the processes involved in the manual arc welding of main gas pipelines during construction and repair, which adversely affect human health and the environment. Gas pipeline welding during construction and repair is performed both in semi-enclosed spaces and in the open air. In both cases, manual arc welding is predominantly used due to its mobility and ease of implementation. The equipment required for arc welding is much cheaper and simpler than that used for laser, electron beam, or hybrid welding. These advantages have led to the widespread use of arc welding across various industries. However, manual arc welding has a considerable negative impact on human health and the environment due to the emissions of toxic substances in the form of welding aerosols. The regularities of aerosol formation during arc welding and the mechanisms of their distribution in the environment are examined, enabling the planning of welding operations in a way that reduces the risk of occupational diseases. Empirical correlations were obtained to determine the concentrations of harmful substances. It was shown that an aerosol cloud, dispersed by wind, spreads with particles diffusing in all directions, leading to a rapid decrease in concentration. It was found that during the welding of pipes under moderate wind conditions, aerosol smoke from a point source spreads in the air in a conical torch shape, expanding both vertically and horizontally. It is substantiated that the main physical process involved is diffusion combined with heat transfer due to convective airflows. Based on Sutton’s modified mathematical model, it was established that during the welding of above-ground pipelines under laminar wind conditions, aerosol smoke mixes with air solely through molecular diffusion, whereas during underground welding, aerosol dispersion is caused by the physical processes associated with the formation of a welding torch.

PL

Przemysł naftowy i gazowniczy cechuje się obecnością i eksploatacją różnych obiektów wysokiego ryzyka, co wiąże się z występowaniem urazów zawodowych i chorób, a także z zanieczyszczeniem środowiska. Wśród tych obiektów szczególnie istotne są systemy rurociągowe, zwłaszcza główne gazociągi. Celem niniejszych badań jest analiza procesów zachodzących podczas ręcznego spawania łukowego głównych gazociągów w trakcie ich budowy i napraw, które mają istotny wpływ na zdrowie ludzi i stan środowiska naturalnego. Spawanie gazociągów podczas budowy i napraw odbywa się zarówno w przestrzeniach półzamkniętych, jak i na wolnym powietrzu. W obu przypadkach stosuje się głównie ręczne spawanie łukowe ze względu na jego mobilność i łatwość zastosowania. Sprzęt niezbędny do spawania łukowego jest znacznie tańszy i prostszy niż ten wykorzystywany do spawania laserowego, wiązką elektronów czy metodami hybrydowymi. Te zalety sprawiają, że spawanie łukowe jest szeroko stosowane w różnych gałęziach przemysłu. Niemniej jednak, ręczne spawanie łukowe ma znaczący negatywny wpływ na zdrowie człowieka i środowisko ze względu na emisję substancji toksycznych w postaci aerozoli spawalniczych. W pracy omówiono prawidłowości tworzenia się aerozoli podczas spawania łukowego oraz mechanizmy ich rozprzestrzeniania się w środowisku, co pozwala na planowanie prac spawalniczych w sposób ograniczający ryzyko chorób zawodowych. Uzyskano empiryczne zależności umożliwiające określenie stężeń substancji szkodliwych. Wykazano, że chmura aerozolu rozpraszana przez wiatr rozprzestrzenia się z cząstkami dyfundującymi we wszystkich kierunkach, co prowadzi do szybkiego spadku stężeń. Stwierdzono, że podczas spawania rur w warunkach umiarkowanego wiatru, dym aerozolowy ze źródła punktowego rozprzestrzenia się w powietrzu w formie stożkowego strumienia, rozszerzającego się zarówno pionowo, jak i poziomo. Wykazano, że głównym procesem fizycznym jest dyfuzja połączona z przenoszeniem ciepła na skutek konwekcyjnych przepływów powietrza. Na podstawie zmodyfikowanego modelu matematycznego Suttona ustalono, że podczas spawania rurociągów naziemnych w warunkach wiatru laminarnego, dym aerozolowy miesza się z powietrzem wyłącznie poprzez dyfuzję cząsteczkową, natomiast w przypadku spawania podziemnego dyspersja aerozoli jest spowodowana procesami fizycznymi związanymi z formowaniem się łuku spawalniczego.

2

Badania szczelności połączeń sieci dystrybucyjnej w aspekcie wykorzystania wodoru.Część 1: Projekt stanowiska i wstępne wyniki

Kroczek Marcin, Kostowski Wojciech, Kulik Kinga

Gaz, Woda i Technika Sanitarna

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2025

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Nr 7-8

12-17

PL

Transport wodoru istniejącymi sieciami dystrybucji gazu ziemnego wiąże się z ryzykiem nieszczelności przez dotychczas szczelne elementy sieci. W artykule przedstawiono projekt dwóch stanowisk badawczych, do badania procesu dyfuzji wodoru przez wybrane elementy sieci, zwłaszcza różnego rodzaju połączenia rozłączne, w warunkach zbliżonych do rzeczywistych. Przedstawiono testowe wyniki badań oraz stwierdzono, że stanowisko II generacji jest gotowe do kontynuacji badań dla szerszego zakresu obiektów i parametrów.

EN

Transporting hydrogen through existing natural gas distribution networks involves the risk of leaks through previously leak-proof network components. The article presents a design for two test rigs for studying the process of hydrogen diffusion through selected network components, especially various types of pipeline connections, under near-real conditions. The first test results are presented and it is concluded that the second-generation test station is ready to continue testing for a wider range of objects and parameters.

3

Machine learning methods for time series prediction of the diffusion curve

Zaręba Mateusz, Skiba Marta

Archives of Mining Sciences

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2025

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Vol. 70, no. 4

561--574

EN

This study employed machine learning techniques to predict time series of diffusion curves, generated in Python with NumPy library. The data was structured as a time series to enable efficient model training and evaluation. Various approaches – statistical, neural, and regression-based – were tested to model the diffusion dynamics. Results revealed notable performance differences: regression models achieved the highest accuracy with the lowest error rates, while time series models like ARIMA and TCN performed worse, likely due to difficulties in capturing the process’s complexity.

4

Analysis of Tribological Wear of Metallic Membranes After the Hydrogenation Process

Rutkowska-Gorczyca Małgorzata, Winnicki Marcin, Kowalewski Piotr

Tribologia

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2024

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nr 2

95--104

EN

The paper presents the results of tribological tests of copper material subjected to the cyclic hydrogenation process. Tribological tests during friction in reciprocating motion, in contact with a ceramic ball. The measurement was performed for different numbers of hydrogenation cycles, different surface roughness and different times after the machining process. The test material consisted of metallic membranes made of dendritic copper particles using the additive method of low-pressure cold gas spraying (LPCS). The hydrogen charging process was carried out using a BioLogis SP50ze potentiostat/galvanostat. The current waveforms were carried out in an electrolyte with a concentration of 0.5 M H2SO4 . Voltammetry (CV measurement) was performed in a three-electrode system, where the metallic membrane was the working electrode. The hydrogen charging process included two ranges: 25 cycles (1 hour) and 50 cycles (2 hours). The system was cyclically loaded with current between a potential of -0.200 V and -1.4 V, with a scanning rate of 20 mV/s. The tests carried out allowed for obtaining the values of the friction coefficient and the wear depth. For materials with a developed surface (high roughness), a decrease in the value of the friction coefficient and the depth of the wear trace was observed with an increase in the number of hydrogenation cycles. This indicates an increase in the amount of hydrogen in the rubbing surface by expanding the surface. In the case of polished samples, the best results were obtained with 25 hydrogenation cycles.

PL

W pracy przedstawiono wyniki badań tribologicznych materiału miedzianego poddanego procesowi cyklicznego nawodorowywania. Badania tribologiczne podczas tarcia w ruchu posuwisto-zwrotnym w styku z kulką ceramiczną wykonano dla różnych ilości cykli nawodorowywania, różnej chropowatości powierzchni i w różnym czasie od procesu obróbkowego. Materiał do badań stanowiły membrany metaliczne wykonane z dendrytycznych cząstek miedzi metodą przyrostową niskociśnieniowego natrysku zimnym gazem (LPCS). Proces ładowania wodorem przeprowadzono z zastosowaniem potencjostatu/galwanostatu BioLogis SP50ze. Przebiegi prądowe prowadzono w elektrolicie o stężeniu 0,5 M H2SO4. Woltamperometrię (pomiar CV) przeprowadzono w układzie trójelektrodowym, gdzie membrana metaliczna stanowiła elektrodę roboczą. Proces ładowania wodorem obejmował dwa zakresy 25 cykle (1 h) oraz 50 cykli (2 h). Układ był cyklicznie prądowo obciążany między potencjałem o wartości -0,200 V a -1,4 V, z szybkością skanowania 20 mV/s. Przeprowadzone badania pozwoliły na uzyskanie wartości współczynnika tarcia oraz głębokości zużycia. Dla materiałów o rozwiniętej powierzchni (duża chropowatość) zauważono zmniejszanie wartości współczynnika tarcia oraz głębokości śladu zużycia wraz ze zwiększaniem ilości cykli nawodorowywania. Wskazuje to zwiększenie ilości wodoru w powierzchni trącej poprzez rozwinięcie powierzchni. W przypadku próbek wypolerowanych najlepsze wyniki uzyskano przy 25 cyklach nawodorowywania.

5

The “diffusion approximation” approach for describing the oil field development process

Mammadov Aziz V., Sultanova Arzu V., Mammadov Ramil M.

Nafta-Gaz

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2024

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R. 80, nr 5

293--300

EN

Analysis of the interaction of wells in the process of oil field development is based in particular on calculating the correlation coefficient of two adjacent wells. However, due to reservoir heterogeneity, this approach fails to consider the possibility of interactions between wells located at significantly greater distances. The non-equilibrium of the system is attributed to its openness, associated with environmental impacts (flooding process and changes in the stock of existing wells). The oil field development is a complex process, subject to complex works such as well grid compaction, carrying out a wide range of geological and technical operations, etc. From this point of view, the development and exploitation of fields needs a “volumetric” approach, i.e. a diffusion approximation. A crucial aspect of oil production is the timely regulation of both current production rates and water impact on the reservoir system. The oscillatory nature of the time series of measurements of oil, water, and liquid production rates carries information about the state and behavior of the reservoir system. Analysis of the features of oscillatory processes of the technological indicators of well operation across the entire area of the deposit as a whole enables early diagnosis of changes in the state of the system. The approach of the production well stock analysis in terms of the amplitude-frequency characteristics of the dynamics of oil, water, “mobile” water, and flooding, as well as the specific ratios of produced oil to the volume of water injected into the reservoir (an indicator of the effectiveness of water stimulation) allows us to consider the development as a diffusion-like process.

PL

Analiza wzajemnego oddziaływania odwiertów na etapie zagospodarowania złóż ropy naftowej opiera się w szczególności na obliczaniu współczynnika korelacji dwóch sąsiadujących ze sobą odwiertów. Jednak ze względu na niejednorodność złoża, podejście to nie uwzględnia możliwości wzajemnego oddziaływania odwiertów położonych w znacznie większych odległościach od siebie. Brak równowagi systemu wynika z jego drożności, związanej z czynnikami środowiskowymi (proces nawadniania złoża i zmiany w stanie zasobów istniejących odwiertów). Zagospodarowanie złóż ropy naftowej jest złożonym procesem, podlegającym skomplikowanym pracom, takim jak zagęszczanie siatki odwiertów, przeprowadzanie szerokiego zakresu zabiegów geologicznych i technicznych, itp. Z tego punktu widzenia zagospodarowanie i eksploatacja złóż wymagają zastosowania podejścia „wolumetrycznego”, tj. aproksymacji dyfuzyjnej. Kluczowym aspektem procesu eksploatacji ropy naftowej jest terminowa regulacja zarówno bieżącego tempa eksploatacji, jak i wpływu wody na system złożowy. Oscylacyjny charakter serii czasowych pomiarów tempa wydobycia ropy, wody i innych mediów dostarcza informacji o stanie i zachowaniu systemu złożowego. Analiza cech procesów oscylacyjnych wskaźników technologicznych funkcjonowania odwiertów na całym obszarze złoża jako całości umożliwia wczesne diagnozowanie zmian w stanie systemu. Zastosowanie analizy zasobów odwiertu wydobywczego pod względem charakterystyki amplitudowo-częstotliwościowej dynamiki ropy naftowej, wody, wody „mobilnej” i nawadniania złoża, a także określonych proporcji wydobytej ropy naftowej względem objętości wody zatłoczonej do złoża (wskaźnik skuteczności stymulacji odwiertu poprzez wtłaczanie wody) pozwala traktować zagospodarowanie złoża jako proces dyfuzyjny.

6

Investigation of Methane-Hydrogen Mixtures in Vertical Pipelines

Marius Darie, Vlasin Nicolae, Prodan Maria, Burian Sorin, Pupazan Gabriela, Moldovan Lucian

Inżynieria Mineralna

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2024

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Vol. 1, no. 1

63--69

EN

The paper presents an assessment of issues regarding the separation phenomena of methane-hydrogen mixtures in vertical pipelines. In the first part of the paper, the explosion risk is underlined. Thus, the widespread use of methane in both the industrial and domestic sectors is well known. In practice, due to recent trends, the injection of hydrogen into dedicated methane installations, the differences in densities can lead to separation phenomena which have an unfavorable effect on the operating regimes of equipment using this mixture and also, on the risk of explosion. The use of hydrogen in the industry is not new, but the increasing impact in terms of the number of users may involve a higher number of accidents due to the increased field of probability of hazardous situations in terms of explosions. The second part presents the used methods. The diffusion and gravitational separation are presented as phenomena having opposite effects. The used methods are theoretical and simulation approaches. The theoretical model is based on a nondynamic model. Therefore, no time parameter was not involved in the model. A linear dependence with the height of the concentration variation was observed for the range of heights considered. The conducted simulation underlined the same conclusion regarding the magnitude of gravitational separations in the methanehydrogen mixtures. The main conclusion of the approach is that the separation phenomenon effect due to the gas density differences is negligible. The approach also revealed, as expected that the higher level of pipe is exposed to a higher risk of increased hydrogen concentration.

7

An iterative approach for solving fractional order Cauchy reaction-diffusion equations

Kumar Manoj

Journal of Applied Mathematics and Computational Mechanics

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2023

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Vol. 22, nr 3

19--32

EN

Reaction-diffusion equations are vitally important due to their role in developing sturdy models in various scientific fields. In the present work, we address an algorithm of the Daftardar-Gejji and Jafari method for solving the nonlinear functional equations of the form ψ = f +L(ψ) + N(ψ). Further, we employ this algorithm to solve Caputo derivative-based time-fractional Cauchy reaction-diffusion equations. We obtain solutions in a series form that converges to a closed form. Furthermore, we perform numerical simulations for the various values of the order of fractional derivatives. The computational procedure of the proposed algorithm is not burdensome. However, it is time-efficient and can easily be implemented using a computer algebra system.

8

Memory dependent triple-phase-lag thermo-elasticity in thermo-diffusive medium

Yadav Anand Kumar, Singh Aarti, Jurczak Paweł

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 4

137--162

EN

The objective of the paper is to look at the propagation and reflection of plane waves in a thermo-diffusion isotropic medium. The reflection of plane waves in a thermo-diffusion medium was investigated in this study with reference to triple phase lag thermo-elasticity. The memory dependent derivative (MDD) is applied for this investigation. The fundamental equations are framed and solved for a particular plane. The four plane waves that are propagating across the medium are, shown namely: longitudinal displacement, P-wave, thermal diffusion T-wave, mass diffusion MD-wave and shear vertical SV-wave. These four plane wave velocities are listed for a specific medium, illustrating the impact of the diffusion coefficient and are graphically represented. Expressions for the reflection coefficient for the incidence plane wave are produced from research on the reflection of plane waves from the stress-free surface. It should be noted that these ratios are graphically represented and shown when diffusion and memory dependent derivative (MDD) factors are in play. The new model is relevant to many different fields, including semiconductors, earth- engineering, and electronics, among others, where thermo-diffusion elasticity is significant. Diffusion is a technique that can be applied to the production of integrated circuits, MOS transistors, doped polysilicon gates for the base and emitter in transistors, as well as for efficient oil extraction from oil reserves. Wave propagation in a thermos-diffusion elastic media provides crucial information about the presence of fresh and enhanced waves in a variety of technical and geophysical contexts. For experimental seismologists, developers of new materials, and researchers, this model might be useful in revising earthquake estimates.

9

Investigations of mass transfer in simulated biomedical systems

Adach-Maciejewska Anna, Kopka Klaudia

Chemical and Process Engineering : New Frontiers

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2023

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Vol. 44, nr 4

art. no. e46

EN

The work motivation was to investigate in vitro system simulating drug release from Drug Eluting Stent (DES). The experiments were conducted in a custom designed unit simulating drug release from polymer covering DES in a simplified way. The active substance diffuses from a thin, internal annular layer of hydrogel (imitating “stent”) to the outer cylindrical layer of hydrogel (“artery wall”) and is at once drifted away by coaxially flowing solution (“blood”). The conducted research proved functionality of the experimental unit. The rate of mass transfer depends considerably on the mass driving force and on the affinity of substance-hydrogel. The volumetric flow rate and liquid viscosity did not affect the process significantly. The effective diffusion coefficient was calculated as a process parameter and then used in the other variants. Diffusion in hydrogel is the mechanism limiting the mass transfer in the examined system. For the first attempt, the diffusive model used in literature was employed. The provided calculations are consistent with experimental data and therefore show that despite its simplifications the model allows to estimate the amount of released substance. In conclusion, the relative substance mass, changing over time, was estimated in the respective parts of the unit. The prospect of determining the relative mass of the substance appearing in the subsequent parts of the system over time provides the opportunity to adjust the respective process parameters, which will facilitate control over the rate of mass release.

10

Influence of diffusion on the reaction of sulfuric acid with ilmenites

Jabłoński Maciej, Lubkowski Krzysztof, Wróblewska Elwira

Chemical and Process Engineering : New Frontiers

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2023

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Vol. 44, nr 3

art. no. e23

EN

The reaction of ilmenite raw materials with sulfuric acid has been investigated to find out the influence of diffusion processes on the course of this reaction. Three different laboratory methods were used to initiate the reaction: mixing ilmenite with 83–85% sulfuric acid at a temperature of 80 ◦C, mixing ilmenite with 90% sulfuric acid at temperatures of 20–40 ◦C and adding water, and mixing ilmenite with water and adding 95% sulfuric acid. Changes of thermal power during the process (thermokinetics) were studied with the use of calorimetry. It was found that diffusion processes play an important role when the reaction is initiated by mixing ilmenite with water followed by the addition of sulfuric acid and are less important when the reaction is initiated by mixing ilmenite with concentrated sulfuric acid followed by the addition of water. To explain the influence of diffusion processes on the reaction, the model calculations based on mass and heat balance equations were involved. Model calculations showed that the diffusion and mass transport processes are so fast that the reaction kinetics is mainly influenced by the reaction on the surface of ilmenite particles. The adopted model of calculations showed a very good agreement with experimental results.

11

Use of solar energy in the technology of fruit drying

Korobka Serhiy, Boyarchuk Vitaliy, Syrotiuk Valerii, Syrotyuk Serhiy, Stukalets Igor, Golovko Volodymyr, Syrotyuk Hanna, Jakubowski Tomasz, Giełżecki Jan

Przegląd Elektrotechniczny

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2022

|

R. 98, nr 6

37--44

EN

Companies in the agri-food industry of Ukraine are trying to rationally manage all forms of energy (including solar energy) needed to implement the production process. The study investigated the process of drying plant material (fruit) based on the use of solar energy (and the intensification of this process). The present process uses a combination of an air collector and a drying chamber. The measurable effect of the performed tests is the development of diagnostic techniques for heat transfer with alternative diffusion and moisture transfer potentials (the experiment was performed at the temperature of 25-60⁰C, drying time was 50-74 hours). The method is offered to calculate the diffusion and moisture transfer when drying the fruit in a solar dryer. The method enables the diagnosis of heat exchange processes and the analysis of the mathematical model of heat exchange processes [1]. The results of the research (analytical and experimental) indicate the possibility of intensifying the fruit drying process based on the solar dryer. The unit energy consumption during fruit drying in a solar dryer is reduced by 3-3.7 MJ/kg in relation to the currently used convection drying devices.

PL

Firmy z branży rolno-spożywczej Ukrainy starają się racjonalnie gospodarować wszystkimi formami energii (w tym energią słoneczną) potrzebną do realizacji procesu produkcyjnego. W pracy zbadano proces suszenia materiału roślinnego (owoców) w oparciu o wykorzystanie energii słonecznej (i intensyfikację tego procesu). Niniejszy proces wykorzystuje połączenie kolektora powietrznego i komory suszącej. Wymiernym efektem przeprowadzonych badań jest opracowanie technik diagnostycznych wymiany ciepła o alternatywnych potencjałach dyfuzji oraz przenoszenia wilgoci (doświadczenie przeprowadzono w temperaturze 25 ⁰C – 60 ⁰C, czas suszenia 50-74 godz.). Metoda oblicza dyfuzję i transfer wilgoci podczas suszenia owoców w suszarce słonecznej. Metoda umożliwia analizę procesów wymiany ciepła oraz modelu matematycznego procesów wymiany ciepła [1]. Wyniki badań (analitycznych i eksperymentalnych) wskazują na możliwość intensyfikacji procesu suszenia owoców w oparciu o suszarkę słoneczną. Jednostkowe zużycie energii podczas suszenia owoców w suszarni solarnej zmniejsza się o 3 MJ/kg - 3,7 MJ/kg w stosunku do obecnie stosowanych urządzeń do suszenia konwekcyjnego.

12

Strouhal number effects on dynamic boundary layer evolution over a wedge surface from initial flow to steady flow: analytical approach

Bachiri Mohamed, Bouabdallah Ahcen

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 4

26--39

EN

The present work studies the effects of the physical parameter characterizing the laminar flow regime, namely the Strouhal number, on the evolution of the unsteady dynamic boundary-layer developed along a wedge surface. Similarity method is used to transform unsteady momentum equation to dimensionless form. Using superposition method between diffusion and convective flows solutions, an ad hoc velocity profile formula is proposed. The obtained results confirm perfectly the numerical data given by Blasius, Falkner-Skan and Williams-Rhyne for all Strouhal numbers. A new accurate analytical function of the local skin friction is established for all time values and for different wedge surface directions. In order to give further clarification on the flows evolutions from diffusion flow to convective flow, in the whole space domain, new skin friction coefficient curves are plotted for all Strouhal numbers and for different wedge surface directions.

13

Water absorption behavior and its effect on Charpy impact test of jute yarn reinforced polyester composites

Djeghader Djamel, Redjel Bachir

Composites Theory and Practice

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2022

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R. 22, nr 2

65--71

EN

Plates of bidirectional jute/polyester composite material were manufactured by the contact molding method. These plates were cut to form notched test pieces 80x15x4 mm and immersed in water (1, 10, 30, 90, 180 and 270 days) in order to study the impact behavior of this material. The studied composite exhibited a water saturation limit after an immersion period of approximately 30 days, with Fickian diffusion of water within the material. Williams’ method based on linear elastic fracture mechanics was used to calculate impact toughness GIC, which is due to the intrinsic characteristics of the material.

14

Effect of chemical composition of boriding agent on the optimization of surface hardness and layer thickness on AISI 8620 steel by solid and liquid boriding processes

Kul Mehmet, Yılmaz Yasin, Oskay Kürşad Oğuz, Kumruoğlu Levent Cenk

Advances in Materials Science

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2022

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Vol. 22, nr 3(73)

14--22

EN

Surfaces of cam shafts made of AISI 8620 steels were hardened by boriding processes in both solid and liquid mediums. Various chemical agents were used to achieve boride layers on the surfaces of the cam shafts in these processes. It was aimed to examine effects of the chemical agents on microhardness and thickness of the boride layers obtained. It was concluded that a bath composition of 5% B4C-90% SiC-5% KBF4 was appropriate for the hardest and thickest boride layer achieved in the solid medium, and a composition of 70% Na2B4O7-30% B4C in the liquid medium.

15

Influence of diffusion and impedence parameters on wave propagation in thermoelastic medium

Kaushal Sachin, Kumar Rajneesh, Parmar Kulwinder

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 4

99--112

EN

The aim of the present paper is to study the impact of diffusion and impedance parameters on the propagation of plane waves in a thermoelastic medium for Green and Lindsay theory (G-L) and the Coupled theory (C-T) of thermoelasticity. Results are demonstrated for impedance boundary conditions and the amplitude ratios of various reflected waves against the angle of incidence are calculated numerically. The characteristics of diffusion, relaxation time and impedence parameter on amplitude ratios have been depicted graphically. Some cases of interest are also derived from the present investigation.

16

Alternative methodology to determine effective coefficient of methane diffusion in coal

Koptoń Henryk

Journal of Sustainable Mining

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2020

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Vol. 19, iss. 2

88--95

EN

The article presents the results of research in to the development of an alternative method of determining the effective coefficient of methane diffusion in coal, based on a mathematical model following Fick's second law. The research was conducted based on the recorded courses of methane sorption kinetics in coal samples obtained in laboratory conditions with the precise gravimetric sorption system IGA-001. The value of the coefficient was treated as an element tuning the model in such a way that the average relative error of the ex post was as small as possible. Model verification indicated the correctness of its assumptions. The development of a more accurate methodology to determine the effective coefficient of methane diffusion in coal will enable the verification of the models applied in order to describe the physical and chemical mechanisms of the methane desorption natural phenomenon. It will also pave the way for further research aimed at the determination of: the gas bearing capacity of coal seams, the degree of degassing of seamswhich results from the mining operations being conducted; or to what extent it is possible to degas the deposits.

17

Przyczyny zawilgacania budynków

Monczyński Bartłomiej

Izolacje

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2020

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R. 25, nr 1

88--90, 92--93

PL

Przedmiotem artykułu są zagadnienia dotyczące hydroizolacji budynków. Omówiono w nim warunki gruntowo-wodne rzutujące na dobór odpowiednich do nich izolacji. Przeanalizowano magazynowanie i transport wody w materiałach porowatych, a także zjawiska sorpcji, kondensacji powierzchniowej i dyfuzji pary wodnej.

EN

This paper concerns the issues related with waterproof insulation of buildings. It also describes the soil and water conditions that affect the selection of proper insulation materials. Storage and transfer of water in porous materials, as well as sorption, surficial condensation and water vapour diffusion have been analysed.

18

On the go-and-stop motion of the discontinuous precipitation front

Chronowski M., Zięba P.

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 2

73--79

EN

The growth of lamellar structure during discontinuous precipitation occurs frequently by so-called go-and-stop fashion. The results of simulation combined with the changes of Cahn’s parameter C revealed two types of such motion. The process takes place in the successive stages which can be distinguished judging from the value of C parameter. For lower values of linear growth rate (v = 10÷20 nm/s) and smaller α lamella thickness (100÷200 nm), the full cycle with relaxation takes 4–6 s. The faster movement of the reaction front (v = 30 nm/s) resulted in dramatic decrease of the full cycle to τtotal = 0.8 s. The same behavior is observed if the α lamella thickness increases beyond 200 nm at constant v equal to 10 nm/s. Both predicted types of go-and-stop motion can experimentally be observed during growth or dissolution of discontinuous precipitates. What is the reason that particular type prevails is unknown, and this is invitation for further studies especially using high-resolution transmission electron microscope operating in in situ mode.

19

A Two-Stage Monte Carlo Approach for Optimization of Bimetallic Nanostructures

Mikhov Rossen, Myasnichenko Vladimir, Kirilov Leoneed, Sdobnyakov Nickolay, Matrenin Pavel, Sokolov Denis, Fidanova Stefka

Annals of Computer Science and Information Systems

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2020

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Vol. 21

285--288

EN

In this paper we propose a two-stage lattice Monte Carlo approach for optimization of bimetallic nanoalloys: simulated annealing on a larger lattice, followed by simulated diffusion. Both algorithms are fairly similar in structure, but their combination was found to give significantly better solutions than simulated annealing alone. We also discuss how to tune the parameters of the algorithms so that they work together optimally.

20

Microstructure and hardness of Pyrowear 53 steel after low-pressure vacuum carburizing at 921°C

Wojtyczka Artur, Iżowski Bartosz

Advances in Manufacturing Science and Technology

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2020

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Vol. 44, nr 4

109--112

EN

The present paper studies and analyzes the low-pressure vacuum carburizing of Pyrowear 53 steel. The carburizing was performed at 921°C. The results after the completion of the treatment process are presented, i.e. microstructure of the surface layer and hardness. The results confirm that carburizing can be effectively used in hardening of the steel.