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Publications from the year 2024
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Numerical Determination of the Load-Bearing Capacity of a Perforated Thin-Walled Beam in a Structural System with a Steel Grating
- Arkadiusz Denisiewicz
- Tomasz Socha
- Krzysztof Kula
- Wojciech Macek
- Wojciech Błażejewski
- Grzegorz Lesiuk
This article presents the results of numerical simulations of a structural system consisting of steel perforated thin-walled beams and a steel grating. The simulations were conducted using the finite element method. The analysis took into account physical and geometric nonlinearity as well as the contact between the steel grating and the beams. The main goal of the research was to develop load-bearing curves for the main beam in the span range of 3–6 m and to identify destruction patterns depending on the span of the structural system. For the purpose of validating the developed numerical model, laboratory tests were conducted on two structural systems with spans of 3 m and 6 m, as well as tests on the strength parameters of the material taken from the tested beams. The laboratory tests confirmed the correctness of the proposed numerical model, which allowed for the simulation of the behavior of the structural system in the full range of spans.
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Numerical Modeling and Simulation of Vehicular Crashes into Three-Bar Metal Bridge Rail
- Howie Fang
- Christopher Jaus
- Qian Wang
- Emre Palta
- Łukasz Pachocki
- Dawid Bruski
Advanced finite element (FE) modeling and simulations were performed on vehicular crashes into a three-bar metal bridge rail (TMBR). The FE models of a sedan, a pickup truck, and a TMBR section were adopted in the crash simulations subject to Manual for Assessing Safety Hardware (MASH) Test Level 2 (TL-2) and Test Level 3 (TL-3) requirements. The test vehicle models were first validated using full-scale physical crash tests conducted on a two-bar metal bridge using a sedan and a pickup truck with similar overall physical properties and sizes to their respective vehicles used in the simulations. The validated vehicular models were then used to evaluate the crash performance of the TMBR using MASH evaluation criteria for structural adequacy, occupant risk, and post-impact trajectory. The TMBR met all MASH TL-2 requirements but failed to meet the MASH TL-3 Criteria H and N requirements when impacted by the sedan. The TMBR was also evaluated under in-service conditions (behind a 1.52 m wide sidewalk) and impacted by the sedan under MASH TL-3 conditions. The simulation results showed that the TMBR behind a sidewalk met all safety requirements except for the occupant impact velocity in the longitudinal direction, which exceeded the MASH limit by 3.93%.
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Numerical modeling of PFAS movement through the vadose zone: Influence of plant water uptake and soil organic carbon distribution
- Barbara Biesek
- Adam Szymkiewicz
- Jirka Simunek
- Anna Gumuła-Kawęcka
- Beata Jaworska-Szulc
In this study, we investigated the effects of soil organic carbon (SOC) distribution and water uptake by plant roots on PFAS movement in the vadose zone with a deep groundwater table under temperate, humid climate conditions. Two series of numerical simulations were performed with the HYDRUS computer code, representing the leaching of historical PFOS contamination and the infiltration of water contaminated with PFOA, respectively. We considered soil profiles with three distributions of SOC (no SOC, realistic SOC distribution decreasing with depth, and uniform SOC equal to the content measured in topsoil), three root distributions (bare soil, grassland, and forest), and three soil textures (sand, sandy loam, and loam). The SOC distribution had a profound impact on the velocity of PFOS movement. The apparent retardation factor for realistic SOC distribution was twice as large as for the scenario with no SOC and more than three times smaller than for the scenario with uniformly high SOC content. We also showed that the root distribution in soil profoundly impacts the simulations of PFAS migration through soil. Including the root zone significantly slows down the movement of PFAS, primarily due to increased evapotranspiration and reduced downward water flux. Another effect of water uptake by plant roots is an increase of PFAS concentrations in soil water (evapo-concentration). The evapo-concentration and the slowdown of PFAS movement due to root water uptake are more significant in fine-textured soils than in sand.
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Numerical modelling of different airbag folding patterns and their influence on occupant responses in frontal vehicle impact
- Łukasz Pachocki
- Howie Fang
This paper presented a procedure for airbag folding for the application in occupant safety studies and analysed the influence of different airbag folding patterns on the occupant severity in frontal impact. Airbags were folded in two patterns: zig-zag and top-roll, using two folding techniques: Initial Metric Method and Explicit Folding. The explicit folding was found to be more expensive in terms of preparation time. However, this approach provided more control over the whole folding process. The Initial Metric Method was more robust, however, it’s hard to apply for complex folding patterns. Deployments of airbags were validated against experimental data of pendulum tests. Those airbag models were applied to 2006 Ford F250 pickup truck. This vehicle was used for simulations of frontal vehicle impact where the 50th male Hybrid III crash test dummy was an occupant. Results of this simulation were compared with an actual test with a similar vehicle, under the same impact conditions. Results showed the head and chest accelerations were lower for top-roll folded airbag cases, however neck normal forces were higher compared to zig-zag folded airbag. The internal pressure in the early stage of deployment was 33% higher for the top-roll folded airbags.
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Numerical Test for Stability Evaluation of Analog Circuits
- Tomasz Stefański
- Piotr Kowalczyk
- Jacek Gulgowski
In this contribution, a new numerical test for the stability evaluation of analog circuits is presented. Usually, if an analog circuit is unstable then the roots of its characteristic equation are localized on the right half-plane of the Laplace s- plane. Because this region is unbounded, we employ the bilinear transformation to map it into the unit disc on the complex plane. Hence, the existence of any root inside the unit disc implies circuit instability. In our test, we employ the global roots and poles finding algorithm based on phase analysis to detect the roots of the characteristic equation inside the unit disc. Unlike other stability tests, our approach allows one to evaluate the stability of analog circuits and systems whose characteristic equations are not polynomials. In order to demonstrate its efficiency, generality and applicability, we analyze a memristor-based chaotic circuit whose stability depends on the value of the fractional-order parameter. The proposed test correctly detects the parameter ranges of either stability or instability for the considered analog circuit.
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Observing its long-term effects on a short-term, multi-day evaluation of the effectiveness of hearing aid use
- Piotr Szymański
- Bożena Kostek
The main objective of the research study was to develop a method for evaluating the effectiveness of hearing protection with hearing aids tailored to the needs and prevailing conditions in the acoustic environments where the elderly most often reside. The method was also intended to estimate the benefits of hearing aids and allow prediction of such an effect based on a short-term trial. It is noteworthy that a short-term evaluation of effectiveness is usually made 30-45 days after the first fitting of hearing aids. The present study evaluated data obtained only after seven days of hearing aid use. Also, modifying the proposed method included the possibility of including a set of sounds, allowing auditory familiarization with environmental situations.
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Occurrence of specific pollutants in a mixture of sewage and rainwater from an urbanized area
- Magdalena Gajewska
- Karolina Fitobór
- Wojciech Artichowicz
- Rafał Ulańczyk
- Małgorzata Kida
- Katarzyna Kołecka
Urban runoff appears to be a pathway for transferring new emerging pollutants from land-based sources to the aquatic environment. This paper aimed to identify and describe the groups of pollutants present in rainwater surface runoff as well as their mixture with wastewater in the combined sewer system from urbanized catchments and to determine the correlations between these pollutants. Four leading groups of new emerging pollutants have been identified that may be present in rainwater and municipal wastewater mixtures. The samples were tested for microplastics, phthalic acid esters, pesticides, and polycyclic aromatic hydrocarbons as well as basic parameters. The pilot site was Słupsk (northwestern Poland). We conducted nine sampling campaigns at three points. The results of the present study revealed that (i) polycyclic aromatic hydrocarbons were not present in the tested samples; (ii) the selected organochlorine pesticides were detected during one campaign in the dry season and therefore were not of critical importance; (iii) out of the 11 analyzed phthalic acid esters, five selected substances released from commonly used plastic products were present; and (iv) the number of microplastics contained in the tested samples ranged from 1,400 to 14,036 pcs/L and evenoccurred during pure rainfall.
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OCENA FUNKCJONOWANIA PASÓW RUCHU DLA ROWERÓW – PRZYPADEK TRÓJMIASTA
- Katarzyna Cholc
- Joanna Wachnicka
Artykuł dotyczy analizy nagrań trzech wybranych odcinków skrzyżowań w Gdańsku, na których znajdują się pasy dla rowerów wyznaczone w ramach jezdni. Na podstawie ww. materiału filmowego została wykonana ocena organizacji i natężenia ruchu, zachowania rowerzystów i kierowców oraz analiza sytuacji konfliktowych. Na każdym z trzech poligonów badawczych zostały przeanalizowane zachowania rowerzystów w ich obrębie. Przedstawiono liczbę rowerzystów na skrzyżowaniach w przedziale godzinowym (od godz. 6.00 do godz. 20.00) w zależności od wybranej przez nich trasy, procentowy udział rowerzystów na wybranych trasach na skrzyżowaniu oraz procentowy udział rowerzystów na pasach rowerowych i poza jezdnią na skrzyżowaniu. Z przedstawionych wyników wywnioskowano, iż niewielu cyklistów skorzystało z dostępnych pasów rowerowych na analizowanych skrzyżowaniach. Znacząca ich liczba wybrała trasy biegnące po chodnikach znajdujących się w obrębie skrzyżowania. Następnie skupiono się na obserwacji interakcji pomiędzy rowerzystami a kierowcami na jezdni. Zostały opisane i zliczone sytuacje niebezpieczne, które powtarzały się najczęściej. Na wszystkich trzech skrzyżowaniach najczęsciej obserwowano najeżdżanie przez pojazdy na pasy rowerowe. Przestrzeń przeznaczona dla rowerzystów była naruszana, co mogłoby się skończyć kolizją. Obserwacje te doprowadziły do postawienia pytania: czy zastosowanie pasów rowerowych w takich miejscach ma sens i czy jest to rozwiązanie bezpieczne dla rowerzystów. Efektem ww. analizy jest stwierdzenie, że stosowanie pasów rowerowych na skrzyżowaniach z dużą liczbą pasów ruchu oraz trudną geometrią skrzyżowania nie jest odpowiednim rozwiązaniem.
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Ocena stanu chemicznego i zagrożeń wód podziemnych oraz powierzchniowych w rejonie Zalewu Wślanego
- Małgorzata Pruszkowska-Caceres
- Patrick Barwinski
- Jakub Bożejewicz
- Szymon Grabowski
- Jakub Kopanicki
- Kacper Aleksandrowicz
The purpose of the research was to examine how factors such as land use and land management affect the quality of groundwater and surface water. These studies were possible thanks to funding from the IDUB Technetium Talent Management Grants project titled “Assessment of Anthropogenic Threat to Groundwater and Surface Water in the Region of the Vistula Lagoon”. The research area included a section of the Vistula Spit, ¯u³awy Wielkie and the coastal waters of the Vistula Lagoon. Field studies were conducted during three field trips; 15 groundwater points and 35 surface water points were examined. During these studies parameters such as temperature, pH, electrical conductivity, and the content of nitrogen, nitrates, phosphates, and sulfates were measured. In the Żuławy area it was found that surface water and groundwater are under the direct influence of the Vistula Lagoon, causing their salinity increase. Locally, man-induced chemical changes are also visible. The inflow of nutrients from fertilization of agricultural fields and uncontrolled discharge of wastes into drainage canals have been observed. The local anthropogenic impact on the water environment was also found in the Vistula Spit area. It was caused by pollutions from tourist facilities.
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On Accelerated Metaheuristic-Based Electromagnetic-Driven Design Optimization of Antenna Structures Using Response Features
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
- Bogdan Pankiewicz
Development of present-day antenna systems is an intricate and multi-step process requiring, among others, meticulous tuning of designable (mainly geometry) parameters. Concerning the latter, the most reliable approach is rigorous numerical optimization, which tends to be re-source-intensive in terms of computing due to involving full-wave electromagnetic (EM) simu-lations. The cost-related issues are particularly pronounced whenever global optimization is necessary, typically carried out using nature-inspired algorithms. Although capable of escaping from local optima, population-based algorithms exhibit poor computational efficiency, to the extent of being hardly feasible when directly handling EM simulation models. A popular miti-gation approach provides the involvement of surrogate modeling techniques, facilitating the search process by replacing costly EM analyses with a fast metamodel. Yet, surrogate-assisted procedures feature complex implementations, and their range of applicability is limited in terms of design space dimensionality that can be efficiently handled. Rendering reliable surrogates is additionally encumbered by highly nonlinear antenna characteristics. This paper investigates potential benefits of employing problem-relevant knowledge in the form of response features into nature-inspired antenna optimization. As demonstrated in the recent literature, re-formulating the design task with the use of appropriately selected characteristics locations of the antenna responses permits flattening the functional landscape of the objective function lead-ing to faster convergence of optimization procedures. Here, we apply this concept to na-ture-inspired global optimization of multi-band antenna structures, and demonstrate its rele-vance, both in terms of accelerating the search process but also improving its reliability. The advantages of feature-based nature-inspired optimization are corroborated through comprehen-sive (based on three antenna structures) comparisons with population-based search involving conventional (e.g., minimax) design problem formulation.
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On effective surface elastic moduli for microstructured strongly anisotropic coatings
- Victor Eremeev
- Giuseppe Rosi
- Salah Naili
The determination of surface elastic moduli is discussed in the context of a recently proposed strongly anisotropic surface elasticity model. The aim of the model was to describe deformations of solids with thin elastic coatings associated with so-called hyperbolic metasurfaces. These metasurfaces can exhibit a quite unusual behaviour and concurrently a very promising wave propagation behaviour. In the model of strongly anisotropic surface elasticity, strain energy as a function of the first and second deformation gradients has been introduced in addition to the constitutive relations in the bulk. In order to obtain values of surface elastic moduli, we compare dispersion relations for anti-plane surface waves obtained using the two-dimensional (2D) model and three-dimensional (3D) straightforward calculations for microstructured coatings of finite thickness. We show that with derived effective surface moduli, the 2D model can correctly describe the wave propagation.
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On mechanics of piezocomposite shell structures
- Mohammad Malikan
This study presents an original and novel investigation into the mechanics of piezo-flexo-magneto-elastic nanocomposite doubly-curved shells (PFMDCSs) and the ability to detect the lower and higher levels of electro-magnetic fields. In this context, by utilizing the first-order shear deformation shell model, stresses and strains are acquired. By imposing Hamilton's principle and the von Kármán approach, the governing equations have been obtained. The intelligent shell model consists of size-dependent influences, viz., strain gradients. This will take place via Mindlin's strain gradient elasticity theory and the subsequent re-establishing of the mathematical framework by incorporating this concept. The strain gradient results in a flexoelectric/flexomagnetic effect. The converse effect of the magnetic field on the basis of a close circuit has been assumed. The developed bending equations have been transferred into the algebraic ones by substituting an analytical technique based on homogeneous immovable simple support for the four edges. The problem has been solved according to the Newton-Raphson iteration scheme, and transverse deflections have been computed. For researching the rightness and precision of the shell models together with the solution process, a comparison is prepared by the finite element method (FEM) results for simplified shells, and a good correlation has been observed. At last, by examining several factors governing the problem, the conditions under which the magnetic effects can be noticeable and dominant in doubly-curved shells have been sought. This study could serve as a benchmark reference for piezoceramic-DCSs, as the presented governing equations are original. The most interesting outcome of this research is that the electro-magnetic response of intelligent structures can be entirely geometry-dependent.
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On Memory-Based Precise Calibration of Cost-Efficient NO2 Sensor Using Artificial Intelligence and Global Response Correction
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
- Marek Wójcikowski
- Bogdan Pankiewicz
Nitrogen dioxide (NO2) is a prevalent air pollutant, particularly abundant in densely populated urban regions. Given its harmful impact on health and the environment, precise real-time monitoring of NO2 concentration is crucial, particularly for devising and executing risk mitigation strategies. However, achieving precise measurements of NO2 is challenging due to the need for expensive and cumbersome equipment. This has spurred the development of more affordable alternatives, although their reliability is often uncertain. The aim of this study is to present a new method for accurately calibrating low-cost NO2 sensors. Our approach utilizes artificial intelligence techniques, particularly neural networks (NNs) acting as surrogates, trained to forecast sensor correction coefficients. These predictions rely on environmental variables (temperature, humidity, etc.), data from additional nitrogen dioxide sensors, and a short series of previous NO2 readings from the main sensor, all serving as inputs for the NN metamodel. As shown, integrating short-time-scale previous measurements significantly improves the quality of the calibration process, further bolstered by global response correction. Similar enhancements are achieved by considering environmental parameter differentials. Our calibration approach has been validated using a custom-built, cost-efficient monitoring platform and reference data collected over five months from high-performance public stations in Gdansk, Poland. The results demonstrate outstanding correction quality, with a correlation coefficient close to 0.93 compared to the reference data and an RMSE below 2.8 µg/m3. This establishes the calibrated sensor as a practical and cost-effective alternative to expensive traditional NO2 monitoring stations.
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On optimal tracking of rapidly varying telecommunication channels
- Maciej Niedźwiecki
- Artur Gańcza
When parameters of mobile telecommunication channels change rapidly, classical adaptive filters, such as exponentially weighted least squares algorithms or gradient algorithms, fail to estimate them with sufficient accuracy. In cases like this, one can use identification methods based on explicit models of parameter changes such as the method of basis functions (BF). When prior knowledge about parameter changes is available the BF approach can be optimized. The paper presents and compares three locally optimized BF algorithms differing in computational requirements. It also demonstrates how the performance of the proposed algorithms can be enhanced in cases where prior knowledge depends on unknown and/or time-varying environmental factors.
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On rotary inertia of microstuctured beams and variations thereof
- Victor Eremeev
- Isaac Elishakoff
We discuss the classic rotary inertia notion and extend it for microstructured beams introducing new microinertia parameters as an additional dynamic response to microstructure changes. Slender structures made of beam- or platelet-lattice metamaterials may exhibit not only large translations and rotations but also general deformations of inner structure. Here we considered a few examples of beam-like structures and derive their inertia properties which include effective mass density, rotary inertia and microinertia. Extended dynamic characteristics related to enhanced kinematics may be crucial for description of origami-like structures or other beam-lattice metamaterials.
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On the Business Analyst's Responsibilities in an Agile Software Project - A Multi-Method Study
- Mateusz Kwiatkowski
- Aleksander Jarzębowicz
[Context] Agile methods are now used in the majority of software projects, but the definitions of such methods rarely include the role of a business analyst (BA). [Objective] This paper investigates the responsibilities assigned to BAs participating in agile software projects. [Method] We identified potential responsibilities through a systematic literature review (3 databases) and interviews with 6 practitioners. The most commonly mentioned responsibilities were further evaluated in a questionnaire survey study with 72 respondents. [Results] The combined findings from the SLR and interviews resulted in 89 unique responsibilities grouped into 7 areas. 49 of these were ranked according to the frequency with which they were assigned in the survey respondents' organizations. [Conclusions] Our findings show that BAs typically support Product Owners (rather than taking on that role) and focus on requirements engineering, business needs, and working closely with development teams.
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On the Fenchel–Moreau conjugate of G-function and the second derivative of the modular in anisotropic Orlicz spaces
- Jakub Maksymiuk
In this paper, we investigate the properties of the Fenchel–Moreau conjugate of G-function with respect to the coupling function c(x, A) = |A[x]2 |. We provide conditions that guarantee that the conjugate is also a G-function. We also show that if a G-function G is twice differentiable and its second derivative belongs to the Orlicz space generated by the Fenchel–Moreau conjugate of G then the modular generated by G is twice differentiable on the Orlicz space generated by G. We also investigate second-order differentiability of action functionals on anisotropic Orlicz–Sobolev spaces.
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On the Possibility of Improving the Oxidation Resistance of High-Chromium Ferritic Stainless Steel Using Reactive Element Oxide Nanoparticles
- Łukasz Mazur
- Aleksander Gil
- Bartosz Kamecki
- Kamil Domaradzki
- Maciej Bik
- Patryk Zając
- Dariusz Zientara
- Sebastian Molin
- Tomasz Brylewski
High-chromium ferritic steels are current the only viable candidates for cheap interconnect materials for application in high-temperature solid oxide fuel and electrolyzer cells (HT-SOFCs/SOECs). The durability and operating characteristics of interconnects manufactured using these materials may be improved significantly by applying a protective-conducting MoCo2O4 coating and depositing an intermediate layer consisting of nanoparticles of Gd2O3—a reactive element oxide—on the surface of the steel substrate. The study demonstrated that the conditions of the thermal treatment of this layered system determine the efficacy of the applied modification with the reactive element. The persistence of this effect was tested over 7000 hours of quasi-isothermal oxidation in air at 800 C.
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On the use of uniaxial one-parameter damage laws for estimating fatigue life under multiaxial loading
- Ricardo Branco
- José Domingos Costa
- L.p. Borrego
- Zbigniew Marciniak
- Wojciech Macek
- Filippo Berto
The goal of this paper is to evaluate the capabilities of different one-parameter fatigue laws to estimate crack initiation in notched components under multiaxial loading. Fatigue damage is accounted for through stress-based, strain-based, and energy-based approaches while the cyclic plasticity at the notch-controlled process zone is estimated using linear-elastic simulations. The results show that energy-based formulations established from both the absorbed energy at the mid-life cycle and the energy absorbed throughout the entire life are more accurate.
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One year performance evaluation of low volume road with cold recycled base course on the basis of FWD and Dynamic Modulus tests
- Mariusz Jaczewski
- Cezary Szydłowski
- Bohdan Dołżycki
Article presents results of assessment of performance of trial section of flexible pavement with cold recycled base constructed on low volume road within typical contract conditions. Performance evaluation was made based on Falling Weight Deflectometer (FWD) test performed during construction stage – 2 times on the top of cold recycled base course – 28 and 180 days after compaction of base course and 2 times on the top of the wearing course – 270 and 360 days after compaction of base course. Deflections and back calculated moduli were analyzed. Additionally, performance of the cold recycled base was determined on the basis of Dynamic Modulus test conducted on the material col-lected during trial section construction. Moduli were determined for 7, 14, 28, 90, 180 and 360 days after the specimen compaction. Performed analysis showed that the development of rheological properties shows similar trends for both field and laboratory tests and proved high bearing capacity of pavements with cold recycled bases.