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1

Impact of sample quantity and absorbance level on particle size analysis by laser diffraction results

Cieślik Ewelina, Kowalczyk Piotr, Czupioł Justyna

Zeszyty Naukowe SGSP / Szkoła Główna Służby Pożarniczej

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2025

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Nr 93 (tom 1)

131--143

EN

This study aimed to investigate the impact of sample quantity and absorbance levels on the repeatability of results and to evaluate the suitability of the method for exhaust gases with low dust concentrations. In the research use was made of the ANALYSETTE 22 NanoTec laser particle size analyser with wet dispersion. Water was used as the dispersing agent. The study utilised Fritsch Standard F500 reference dust, with a particle size range of 0.5–50 μm, and two dust samples collected from industrial installations. Variations in the results were observed depending on the sample mass introduced into the analyser and the resulting absorbance levels. For the reference dust, repeatable results, consistent with the manufacturer’s specifications, were obtained with absorbance levels of 5–20%. Similarly, the most reproducible results for real dust samples were obtained at comparable absorbance levels. The study emphasized the lack of repeatability at absorbance levels below 5%, which may be attributed to the insufficient amount of dust analysed. It seems necessary to develop an alternative method for collecting dust samples from exhaust gases to avoid relying on dust recovery from filtration materials.

2

Parametric Analysis of Damage in Cancellous Bone and in Materials with Bone-like Microstructure

Kowalczyk Piotr

Computer Assisted Methods in Engineering and Science

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2025

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Vol. 32, no. 3

237--253

EN

A systematic approach to the macroscopic damage analysis of bone-like cellular materials is presented in which damage conditions are expressed as tabularized functions of microstructure geometry parameters. Based on three different strain-based microscopic damage criteria, a large number of cellular microstructures, characterized by different values of geometric parameters, are analysed by the finite element method to determine damage factor values for a number of macroscopic strain states. As a result, an exhaustive database is prepared in which macroscopic damage conditions for a variety of microstructures are presented as tabularized parametric functions of both geometric parameters and strain states. A numerical procedure of data interpolation is proposed as a tool to predict parameterized damage surfaces for any bone-like microstructure. The results are made publicly available in an open data repository to enable further research on their characterization and analytical approximation.

3

Porównanie wydajności wieloplatformowych frameworków Xamarin i Flutter

Kowalczyk Piotr, Dzieńkowski Mariusz

Journal of Computer Sciences Institute

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2024

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Vol. 32

199--204

PL

W ramach artykułu przeprowadzono wydajnościowe badania porównawcze dwóch wieloplatformowych szkieletów programistycznych Flutter oraz Xamarin. W tym celu opracowano dwie aplikacje testowe pracujące pod kontrolą systemu Android, realizujące te same funkcje tzn. operacje CRUD na bazie danych oraz sortowanie przez scalanie tablic obiektów. Testy przeprowadzono na emulatorze oraz na urządzeniu fizycznym. Sortowane tablice miały różne rozmiary, a operacje na bazie były realizowane dla różnej wielkości zbiorów danych. Metryką wykorzystaną do porównań był średni czas realizacji danej operacji. Analiza wyników badań pokazała, że Xamarin był zdecydowanie wydajniejszy w trzech operacjach CRUD, natomiast Flutter znacznie szybciej wykonywał operacje obliczeniowe, którą było w tym przypadku sortowanie.

EN

This article conducts a performance comparative study of two cross-platform development frameworks: Flutter and Xamarin. For this purpose, two test applications running on Android were developed, implementing the same functions, i.e. CRUD operations on the database and sorting an array of objects by the Merge Sort algorithm. Tests were performed on an emulator and on a physical device. The sorted arrays had different sizes, and database operations were performed for different sizes of data sets. The metric used for comparisons was the average implementation time of a given operation. The analysis of the research results showed that Xamarin was definitely more efficient in three CRUD operations, while Flutter performed computational operations, which in this case was sorting, much faster.

4

FEM Analysis of Residual Stresses in Welded Aluminum and Polyamide 6

Praski Marcin, Kowalczyk Piotr, Szumowski Radosław, Stankiewicz Karolina, Leski Andrzej

Fatigue of Aircraft Structures

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2024

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Iss.16

57--74

EN

Thermoplastic composites enable weldable, recyclable aircraft structures, but thermal mismatch between metals and polymers can introduce detrimental residual stresses. This study develops a finite element method (FEM) framework to predict residual stress fields in resistance-welded joints between aluminum 7075 and carbon-fiber-reinforced polyamide 6 (PA6). Transient thermal analyses with multilinear, temperature-dependent properties were coupled to mechanical analyses; contact conditions transitioned from frictional to bonded at PA6 melting. Three thermal cycles (20°C→220°C→20°C, 20°C→240°C→20°C, 20°C→260°C→20°C) were examined to assess peak-temperature effects. The simulations show stress contours that decay with distance from the bond and reveal pronounced peaks in both normal and shear components at weld edges, consistent with shear-lag theory. Within the bonded interior, average stresses are relatively low, whereas edge concentrations identify likely sites for debonding or delamination initiation. The magnitude of residual stresses increases with thermal gradient, underscoring the need for parameter control during welding. The FEM outputs will be validated against uniaxial tension and three-point bending tests on welded specimens, with future work quantifying fatigue-life reduction under combined thermal and mechanical cycling. The results highlight mitigation priorities for bonded repairs and hybrid aerospace structures, including process-curve tuning (current/pressure/cooling) and edge-region design measures.

5

Determination of condensable particulate matter released by the combustion of solid fuels in low-power boilers

Cieślik Ewelina, Kwaśniok Piotr, Rachwał Tomasz, Kowalczyk Piotr

Zeszyty Naukowe SGSP / Szkoła Główna Służby Pożarniczej

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2023

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Nr 85

81--92

EN

Despite significant emission control steps in recent decades, damage to air quality caused by particulate matter with a diameter of 2.5 μm or less is now a major concern on a global scale. Condensable particulate matters (CPM), due to their significant contribution to the total concentration of particulate matter and their small aerodynamic size (below 2.5 μm), are now of widespread interest. CPMs produced in low-power solid fuel heating systems can be one of the main components of the total mass of fine particles present in the air we breathe. The operating conditions of large power installations and small heating boilers differ significantly, therefore it is necessary to adopt the research methods adapted to industrial installations to the low-power boilers. In the tests, three fuels were combusted in two low-power boilers (18 kW boiler with a suction feeder and 5class 14 kW boiler with a screw feeder): bituminous coal, pine and spruce wood pellets and cereal straw pellets. An EPA 202 method was used to collect the CPM. Qualitative and quantitative analyses of inorganic and organic CPM components were performed. Analyses of the inorganic part of the CPM included the determination of metals m.in Na, Ca, Fe, Mg, Al, K, and water-soluble ions, m.in SO4 2−, Na+, K+ and Cl−, while analyses of the organic part of the CPM comprised the determination of PAHs. Differences were observed in the amount of CPM generated depending on the fuel used and the type of low-power boiler used. CPM emissions are relatively high and constitute a large part of total particulate matter, so the impact of CPM on the environment cannot be ignored and we should pay special attention to its research and control, especially from small solid fuel heating boilers.

PL

Mimo podjęcia w ostatnich dekadach znaczących kroków w zakresie kontroli emisji, szkody w jakości powietrza spowodowane przez cząstki stałe o średnicy 2,5 μm lub mniejszej stanowią obecnie główne zmartwienie w skali globalnej. Składniki pyłu zawieszonego, ulegające kondensacji (CPM) ze względu na ich znaczny wkład w całkowite stężenie cząstek stałych i ich mały rozmiar aerodynamiczny (poniżej 2,5 μm), cieszą się obecnie powszechnym zainteresowaniem. CPM wytwarzane w instalacjach grzewczych małej mocy na paliwo stałe mogą być jednym z głównych składników całkowitej masy drobnych cząstek obecnych w powietrzu, którym oddychamy. Warunki pracy dużych instalacji energetycznych i małych kotłów grzewczych znacząco się różnią, dlatego też konieczne jest dostosowanie metod badawczych przystosowanych do przemysłowych instalacji, do kotłów małej mocy. W badaniach w dwóch kotłach małej mocy (18 kW kocioł z podajnikiem podsuwowym oraz 14 kW kocioł 5 klasy z podajnikiem ślimakowym) spalano trzy paliwa: węgiel kamienny, pellet sosnowo-świerkowy oraz pellet ze słomy zbożowej. W celu pobrania CPM zastosowano metodę EPA 202. Wykonano jakościowe i ilościowe analizy nieorganicznych i organicznych składników CPM. Analizy części nieorganicznej CPM obejmowały oznaczanie metali, m.in. Na, Ca, Fe, Mg, Al, K i jonów rozpuszczalnych w wodzie, m.in. SO4 2−, Na+, K+ i Cl−, natomiast analizy części organicznej CPM obejmowały oznaczenie m.in. WWA. Zaobserwowano różnice w ilości powstających CPM w zależności od stosowanego paliwa i stosowanego typu kotła małej mocy. Emisja CPM jest stosunkowo wysoka i stanowi dużą część całkowitego pyłu, dlatego nie można zignorować wpływu CPM na środowisko i powinniśmy zwrócić szczególną uwagę na jego badania i kontrolę szczególnie z małych kotłów grzewczych na paliwo stałe.

6

Discussion on angular asymmetry in the solutions of SLIP model

Kowalczyk Piotr, Płociniczak Łukasz, Wróblewska Zofia

Mathematica Applicanda

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2023

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Vol. 51, no. 2

223--237

EN

We consider a spring-mass model of human running which is built upon an inverted elastic pendulum. The model itself consists of two sets of differential equations - one set describes the motion of the centre of mass of a runner in contact with the ground (support phase), and the second set describes the phase of no contact with the ground (flight phase). In our previous approach, we assumed that periodic solutions in the support phase are symmetrical with respect to the touch-down and take-off angles for the large spring constant (or small angle of attack). Based on proposed solutions, we introduce analytical approximations of an asymmetrical boundary value problem, which brings our model closer to real running. By appropriately concatenating asymptotic solutions for the two gait phases, we are able to reduce the dynamics to a one-dimensional apex to apex return map and then to investigate the existence and stability of periodic solutions. Unlike in the symmetrical version, we could not find sufficient conditions for this map to have a unique stable fixed point. Extending the model with the possibility of taking off with the angle other than during landing, the aforementioned asymmetry, is necessary in the context of real run considerations. Thanks to this, our work could be enriched by experimental results. In this paper, we will present the possible reasons for the instability of asymmetric solutions in conjunction with conclusions from the observation of real runs.

PL

W pracy rozważamy model biegu, w którym człowiek sprowadzony jest do punktu masy na nieważkiej sprężynie, a momencie kontaktu z podłożem staje się odwróconym sprężystym wahadłem. Sam model składa się z dwóch zestawów równań różniczkowych - jedno opisuje ruch środka masy biegacza podczas kontaktu stopy z podłożem (faza podparcia), a drugi fazę lotu. W naszym poprzednim podejściu zakładaliśmy, że rozwiązania okresowe w fazie podparcia są symetryczne względem kątów lądowania i odbicia dla dużej wartości sztywności nogi (lub małego kąta ataku). Na podstawie proponowanych rozwiązań wprowadzamy analityczne przybliżenia asymetrycznego problemu brzegowego, co zbliża nasz model do rzeczywistego biegu. Odpowiednio łącząc asymptotyczne rozwiązania dla obu faz biegu, jesteśmy w stanie zredukować dynamikę do jednego wymiaru i utworzyć odwzorowanie powrotu od wierzchołka do kolejnego wierzchołka praboli lotu, a następnie badać istnienie i stabilność rozwiązań okresowych. W odróżnieniu od wersji symetrycznej, nie mogliśmy znaleźć wystarczających warunków, aby to odwzorowanie miało jednoznacznie określony stabilny punkt stały. Rozszerzenie modelu o możliwość odbicia pod innym kątem, niż podczas lądowania (asymetria), jest konieczne w kontekście rozważań nad rzeczywistym biegiem. Dzięki temu nasza praca mogła zostać wzbogacona o wyniki eksperymentalne. W tym artykule przedstawimy możliwe przyczyny niestabilności asymetrycznych rozwiązań w połączeniu z wnioskami z obserwacji rzeczywistych biegów.

7

Resonance of a structure with soil elastic waves released in non-linear hysteretic soil upon unloading

Kowalczyk Piotr

Studia Geotechnica et Mechanica

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2022

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Vol. 44, nr 4

253--266

EN

High-frequency motion is often observed in small-scale experimental works carried out in flexible containers under simplified seismic loading conditions when single harmonic sine input motions are introduced at the base of a soil specimen. The source of the high-frequency motion has often been sought in experimental inaccuracies. On the other hand, the most recent numerical studies suggested that high-frequency motion in the steady-state dynamic response of soil subjected to harmonic excitation can also be generated as a result of soil elastic waves released in non-linear hysteretic soil upon unloading. This work presents an example of a finite element numerical study on seismic soil–structure interaction representative of an experimental setup from the past. The results show how high-frequency motion generated in soil in the steady-state response, apparently representative of soil elastic waves, affects the steady-state response of a structure, that is, it is presented how the structure in the analysed case resonates with the soil elastic waves. The numerical findings are verified against the benchmark experimental example to indicate similar patterns in the dynamic response of the structure.

8

Military technology in mine rescue

Hałys Piotr, Kowalczyk Piotr

Scientific Journal of the Military University of Land Forces

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2021

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Vol. 53, No. 1(199)

178--197

EN

The sense of security is an individual's one-sided personal expression referring to one's awareness of existing threats and potential possibilities of their prevention. Thus we can observe a permanent development of technologies developed to meet the needs of military operations aimed at neutralizing threats related to explosives of military origin, as well as any improvised explosive devices. Threats are the events that adversely affect life, health, property or the environment, therefore, the mentioned technologies can be used in the civilian market as well. This article presents military systems that have been developed by Alford Technologies Ltd. ('The World's Leading Provider of User-Filled Explosive Chargers and Disruptors'). The systems that have been named ReBar Cutters™ and DIOPLEX™ have been developed to save the lives of soldiers, military equipment and any relevant infrastructure while conducting a wide scope of combat operations throughout the world. The systems can for example be easily used as an alternative support for mining rescue teams during mine rescue operations. The authors intend to present the above-mentioned systems due to their precision, accuracy, and most importantly, because the products are user-filled and therefore can be prepared on site and ready to use very fast. Tests of systems named ReBar Cutters™ and DIOPLEX™ presented in the study were carried out in Zakłady Górnicze Polkowice-Sieroszowice Oddział KGHM Polska Miedź S.A. at a depth of 850 m in order to check their effectiveness in the future environment (pressure, humidity, temperature, dust). The presented shaped charges with cumulative insert were elaborated with explosives used in mining – RIOPRIME 25 (Mini Primer) and ERGODYN 22E – and used for the cut steel structural elements (steel anchor rod), steel leveling cable, sheathed electric mining cable and an element form bucket loader type LKP 903. The tests were not financed, and the obtained results were part of the research in one of the author's PhD dissertation.

PL

Poczucie bezpieczeństwa to wyraz jednostronnego aspektu podmiotu, odnoszący się do świadomości istnienia zagrożeń i wiedzy o możliwościach zapobiegania niebezpieczeństwom. Stąd zauważyć można permanentny rozwój technologii opracowywanych na potrzeby działań wojskowych ukierunkowanych na neutralizację zagrożeń związanych z przedmiotami wybuchowymi pochodzenia wojskowego, jak i improwizowanych urządzeń wybuchowych. Zagrożenia to zdarzenia, które mogą wpływać niekorzystnie na życie, zdrowie, mienie lub środowisko, więc jak praktyka wskazuje, technologie te mogą również być używane na rynku cywilnym. Opisywane w artykule systemy ReBar Cutters™ i DIOPLEX™ opracowane przez firmę Alford Technologies Ltd. mające w praktyce ratować życie żołnierzy, sprzęt i infrastrukturę w rejonach konfliktów zbrojnych mogą stanowić realne, alternatywne wsparcie systemu ratownictwa górniczego. W ramach realizacji zadań związanych z ratowaniem życia ludzkiego może zaistnieć konieczność pokonania przeszkód w postaci stalowych elementów stanowiących infrastrukturę techniczną wyrobiska. W przypadku braku możliwości użycia standardowego sprzętu ratowniczego (np. pneumatycznego) może zaistnieć konieczność użycia systemów wykorzystujących materiały wybuchowe, o których istnieniu, jak i możliwościach warto wiedzieć. Intencją autorów jest zaprezentowanie powyższych systemów używanych w wojsku ze względu na ich precyzję działania oraz łatwość, szybkość i prostotę przygotowania gotowego ładunku w miejscu jego użycia. Przedstawione w opracowaniu testy systemów ReBar Cutters™ i DIOPLEX™ przeprowadzone zostały w Zakładach Górniczych Polkowice-Sieroszowice Oddziale KGHM Polska Miedź S.A. na głębokości 850 m w celu sprawdzenia ich skuteczności działania w przyszłym środowisku (ciśnienie, wilgotność, temperatura, zapylenie). Kształtki obu systemów elaborowane były górniczymi materiałami wybuchowymi RIOPRIME 25 (Mini Primer) oraz ERGODYN 22E i użyte do przecięcia stalowych elementów konstrukcyjnych (kotwy), stalowej liny wyrównawczej, kabla elektroenergetycznego oraz elementu z lemiesza ładowarki łyżkowej typu LKP 903. Testy nie były finansowane, a uzyskane wyniki stanowiły element badań w pracy doktorskiej jednego z autorów.

9

Risk Reduction of a Terrorist Attack on a Critical Infrastructure Facility of LGOM Based on the Example of the Żelazny Most Tailings Storage Facility (OUOW Żelazny Most)

Bac-Bronowicz Joanna, Kowalczyk Piotr, Bartlewska-Urban Monika

Studia Geotechnica et Mechanica

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2020

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Vol. 42, nr 4

367--387

EN

This paper identifies the threats and risks of a terrorist attack on a critical infrastructure facility based on the example of Żelazny Most Tailings Storage Facility (OUOW). The threat analysis primarily took into account the threats of deliberate human actions. Identification of potential threats concerning the infrastructure surrounding the facility was conducted based on information that is readily available on the Internet. The reasons why it may be a potential target were also justified. Numerical calculations of the stress–deformation scale of the initial state of the reservoir, based on the Biot model with the Kelvin–Voight rheological skeleton, were presented as a starting point for in-depth research on the scale of threats and risks to the reservoir. The presented numerical model can be a starting point for calculating the stability of a reservoir subjected to explosives. The facility constitutes a major element of Lubińsko-Głogowski Okręg Miedziowy (Lubin-Głogów Copper District). OUOW Żelazny Most is the biggest such facility in Europe and is utilized to collect tailing waist. When expanded in its southern quarter, the facility will be the biggest in the world.

10

Modular Test Stand for Fatigue Testing of Aeronautical Structures - Verification of Assumptions

Leski Andrzej, Wronicz Wojciech, Kowalczyk Piotr, Szmidt Michał, Klewicki Robert, Włodarczyk Karol, Uliński Grzegorz

Fatigue of Aircraft Structures

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2020

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Iss. 12

78--91

EN

The Modular Test Stand was developed and manufactured to decrease the cost of fatigue testing and reduce the time of its completion as well as to enable testing specimens under more complex load conditions. The stand consists of three connected sections, similar to a wing box, all being loaded in the same way. Thanks to that, several specimens can be tested simultaneously. This configuration requires that stress and strain distribution should be reasonably uniform, as assumed in the design stage. The structure can be loaded with bending or torsion. A whole section, selected structural node or a specimen mounted in the structure as well as a repair or a sensor can be a test object. Two stands, one for bending and one for torsion were prepared. This paper presents the verification of the assumed strain and stress distributions on the skin panels. The measurements were performed with the use of Digital Image Correlation (DIC) as well as strain gauges. DIC measurements were performed on one skin panel of the central section. Five strain gauge rosettes were installed on both panels of the one section. In addition, one rosette was applied to one skin panel in each of two other sections. Measurements were performed on the stand for torsion as well as on the stand for bending. The results of DIC analysis and strain gauge measurement during torsion show uniform shearing strain distributions on the panels. During bending, on the tensioned side, the strains obtained indicate quite uniform strain distributions. On the compressed side, local buckling of the skin panels results in high strain gradients. Strain levels obtained with the use of a DIC analysis and strain gauge measurements were similar. Moreover, horizontal displacements of markers in the spar axis during bending was determined based on a series of photographic. The deflection line obtained in this way has a shape similar to arc, which is characteristic of the constant bending moment. The stand was tested with torsional and bending loads in order to verify the design assumptions. The results of strain distributions on the skin panels with the use of DIC and strain gauges as well as the deflection line of the spar axis indicate that the Modular Test Stand performs as assumed and can be used for tests.