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Gdańsk University of Technology

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  • Driver’s Condition Detection System Using Multimodal Imaging and Machine Learning Algorithms
    • Paulina Leszczełowska
    • Maria Bollin
    • Karol Lempkowski
    • Mateusz Żak
    • Jacek Rumiński
    2023

    To this day, driver fatigue remains one of the most significant causes of road accidents. In this paper, a novel way of detecting and monitoring a driver’s physical state has been proposed. The goal of the system was to make use of multimodal imaging from RGB and thermal cameras working simultaneously to monitor the driver’s current condition. A custom dataset was created consisting of thermal and RGB video samples. Acquired data was further processed and used for the extraction of necessary metrics pertaining to the state of the eyes and mouth, such as the eye aspect ratio (EAR) and mouth aspect ratio (MAR), respectively. Breath characteristics were also measured. A customized residual neural network was chosen as the final prediction model for the entire system. The results achieved by the proposed model validate the chosen approach to fatigue detection by achieving an average accuracy of 75% on test data

  • Driving forces of informal employment: An empirical study based on Polish enterprise data
    • Dagmara Nikulin
    2023 Full text Entrepreneurial Business and Economics Review

    Objective: The article aims to indicate the determinants of informal employment in registered enterprises using company-level evidence from Poland. Research Design & Methods: The survey conducted among Polish small and medium-sized (SME) enterprises in 2018 was used to find the driving forces of informal employment in Poland. The adequate sample comprised 952 representative surveys derived from the computer-assisted telephone interview (CATI). The quantitative analysis was based on the logistic regression. Findings: The findings indicate that among the main drivers of informal employment, one can distinguish the level of tax morality of owners or company managers and the administrative difficulties related to setting up a business. The role of non-economic factors in creating informal activities was confirmed. Moreover, informal employment was more prevalent in smaller companies operating in the construction industry. Implications & Recommendations: Our analysis may be helpful for both research in entrepreneurship and tax evasion and the shadow economy stream. It indicates the heterogeneity among Polish enterprises related to the involvement in informal activities, particularly informal labour. Our study sheds light onto the less known dimension of ‘grey activities’ existing in the registered companies, which is less frequently analysed in the literature. Contribution & Value Added: This evidence will help us understand the primary motives for using the informal workforce and enhance further research on the nature and extent of informal employment and the shadow economy in general.

  • Driving the Image of an Electricity Supplier through Marketing Activities
    • Dariusz Dąbrowski
    • Jakub Dąbrowski
    • Tomasz Zamasz
    • Marcin Lis
    2023 Full text Forum Scientiae Oeconomia

    The aim of this study is to determine how marketing actions undertaken within the marketing mix by electricity providers influence their image. Referring to the Stimulus-Organism-Response (SOR) theory, research hypotheses were formulated, and a regression model was constructed, assuming positive impacts of selected marketing actions of electricity providers on their image. A quantitative approach was employed to test the research hypotheses. Data were collected through a questionnaire survey among randomly selected 503 domestic electricity consumers, and statistical analysis was used for data analysis. The research results indicate that the following marketing activities of electricity providers have a positive impact on their image: offering other products along with electricity, providing price discounts, providing physical customer service offices, and engagement in sponsorship.

  • Dual-Setting Bone Cement Based On Magnesium Phosphate Modified with Glycol Methacrylate Designed for Biomedical Applications
    • Marcin Wekwejt
    • Maryia Khamenka
    • Anna Ronowska
    • Uwe Gbureck
    2023 Full text ACS Applied Materials & Interfaces

    Magnesium phosphate cement (MPC) is a suitable alternative for the currently used calcium phosphates, owing to beneficial properties like favorable resorption rate, fast hardening, and higher compressive strength. However, due to insufficient mechanical properties and high brittleness, further improvement is still expected. In this paper, we reported the preparation of a novel type of dual-setting cement based on MPC with poly(2-hydroxyethyl methacrylate) (pHEMA). The aim of our study was to evaluate the effect of HEMA addition, especially its concentration and premix time, on the selected properties of the composite. Several beneficial effects were found: better formability, shortened setting time, and improvement of mechanical strengths. The developed cements were hardening in ∼16–21 min, consisted of well-crystallized phases and polymerized HEMA, had porosity between ∼2–11%, degraded slowly by ∼0.1–4%/18 days, their wettability was ∼20–30°, they showed compressive and bending strength between ∼45–73 and 13–20 MPa, respectively, and, finally, their Young’s Modulus was close to ∼2.5–3.0 GPa. The results showed that the optimal cement composition is MPC+15%HEMA and 4 min of polymer premixing time. Overall, our research suggested that this developed cement may be used in various biomedical applications.

  • Dynamic GPU power capping with online performance tracing for energy efficient GPU computing using DEPO tool
    • Adam Krzywaniak
    • Paweł Czarnul
    • Jerzy Proficz
    2023 Future Generation Computer Systems-The International Journal of Grid Computing-Theory Methods and Applications

    GPU accelerators have become essential to the recent advance in computational power of high- performance computing (HPC) systems. Current HPC systems’ reaching an approximately 20–30 mega-watt power demand has resulted in increasing CO2 emissions, energy costs and necessitate increasingly complex cooling systems. This is a very real challenge. To address this, new mechanisms of software power control could be employed. In this paper, a dynamic new method of limiting software power is introduced on one of the latest NVIDIA GPUs: a software tool called the Dynamic Energy- Performance Optimiser (DEPO). DEPO minimizes the energy consumption of the CUDA based GPU workloads, with respect to one of the three given metrics: minimum of energy (E), Energy-Delay product (EDP) and Energy-Delay sum (EDS). The tool gathers power measurements from NVIDIA Management Library (NVML). Measuring the application progress at runtime is based on CUDA Profiling Tools Interface (CUPTI) kernel-counting. We have evaluated the DEPO tool on the NVIDIA RTX A4500 and A100 GPUs with machine learning workloads. Depending on the application (training of neural networks: Resnet152, Densenet161, VGG- 19 or a GEMM benchmark) for the E target metric, we were able to obtain energy savings exceeding 22% for both NVIDIA A100 and RTX A4500 GPUs while the performance drop has never been higher than 20%. Using one of the bi-objective EDP or EDS metrics allowed finding configurations resulting in 15% or 18% of energy saved with only 8% of performance loss. For most of the experiments the percentage-wise performance penalty is lower than the energy savings. This demonstrates its potential for energy consumption reduction in HPC systems with GPU accelerators.

  • DYNAMIC POSITIONING CAPABILITY ASSESSMENT BASED ON OPTIMAL THRUST ALLOCATION
    • Agnieszka Piekło
    • Anna Witkowska
    • Tomasz Zubowicz
    2023 Full text Polish Maritime Research

    The article presents an efficient method of optimal thrust allocation over the actuators in a dynamically positioned ship, according to the DNV-ST-0111 standard, Level 1. The optimisation task is approximated to a convex problem with linear constraints and mathematically formulated as quadratic programming. The case study is being used to illustrate the use of the proposed approach in assessing the DP capability of a rescue ship. The quadratic programming- based approach applied for dynamic positioning capability assessment allows for fast calculations to qualitatively compare different ship designs. In comparison with the DNV tool, it gives 100% successful validation for a ship with azimuth thrusters and a pessimistic solution for a ship equipped with propellers with rudders. Therefore, it can be safely applied at an early design stage.

  • Dziecięce pieluchy jednorazowe: walory konsumenckie a wpływ na zdrowie dziecka pod kątem zawartości związków endokrynnie czynnych
    • Aneta Chabowska
    • Justyna Płotka-Wasylka
    • Natalia Jatkowska
    2023 Full text Analityka: Nauka i Praktyka

    Układ hormonalny reguluje wiele procesów zachodzących w organizmie ludzkim. Jego funkcjonowanie może zostać zaburzone przez działanie związków z grupy endokrynnie czynnych (ang. Endocrine Disrupting Compounds, EDC) obecnych w otaczającym nas środowisku. Związki te mogą wpłynąć szkodliwie nie tylko na osobę eksponowaną na ich bezpośrednie działanie, ale również na jej potomstwo. Wyniki wieloletnich badań umożliwiły stwierdzenie, że związki EDC mogą powodować mutacje, prowadzące następnie do zmian nowotworowych, jak również dezaktywować niektóre procesy zachodzące w organizmie, niezbędne do zachowania homeostazy. Z uwagi na negatywny wpływ EDC na organizm ludzki szczególnie ważnym wydaje się monitorowanie ich zawartości w produktach przeznaczonych dla dzieci, których mechanizmy detoksykacji nie są jeszcze w pełni rozwinięte. Jednym z dóbr konsumenckich stosowanych od pierwszych dni życia dziecka są pieluchy jednorazowe. Niemniej jednak należy zadać sobie pytanie czy produkt ten jest bezpieczny dla dzieci pod kątem zawartości związków chemicznych, w tym ECD.

  • Dziedzictwo lokalne w kontekście programu Reconnecting With Your Culture Poland / UNESCO, prelekcje w ramach Pomorskiej Nocy Naukowców, prelekcje: "Rola dziedzictwa lokalnego" (AK), "Dzieci a rozumienie dziedzictwa: (PDŻ)
    • Agnieszka Kurkowska
    • Paulina Duch-Żebrowska
    2023

    Tematem prelekcji było lokalne dziedzictwo kulturowe oraz postawy obywatelskie, ponieważ tylko poznanie i pogłębienie dziedzictwa kulturowego pozwala docenić teraźniejszość i dobrze budować przyszłość.

  • Ecology In Tribology: Selected Problems of Eliminating Natural Oil-Based Lubricants from Machine Friction Couples
    • Michał Wasilczuk
    • Jacek Łubiński
    • Katarzyna Zasińska
    2023 Full text TRIBOLOGIA

    The elimination of mineral oil-based lubricants from machines has multiple beneficial effects on the natural environment. Firstly – these lubricants are a direct threat to the environment in the event of leaks; secondly – their elimination reduces the demand for crude oil from which they are obtained. In addition, in many cases, e.g. when replacing traditional lubricants with water, friction losses in the bearings can also be reduced due to the lower viscosity of the water, which reduces the energy dissipation in machines. On the other hand, the introduction of self-lubricating materials or water-lubricated bearings causes problems related to the need to adapt the design of machines and materials used to new operating conditions and changed properties of the lubricants. In the paper, selected examples of problems related to the use of ecological lubricants are discussed. The high cost of PEEK based polymers resulted in the emergence of cheaper substitutes on the market; however, in the conducted research, the substitutes presented worse properties than those declared by their manufacturers

  • Edge and Pair Queries-Random Graphs and Complexity
    • Dariusz Dereniowski
    • Przemysław Gordinowicz
    • Paweł Prałat
    2023 Full text ELECTRONIC JOURNAL OF COMBINATORICS

    We investigate two types of query games played on a graph, pair queries and edge queries. We concentrate on investigating the two associated graph parameters for binomial random graphs, and showing that determining any of the two parameters is NP-hard for bounded degree graphs.

  • Edge coloring of graphs of signed class 1 and 2
    • Robert Janczewski
    • Krzysztof Turowski
    • Bartłomiej Wróblewski
    2023 DISCRETE APPLIED MATHEMATICS

    Recently, Behr (2020) introduced a notion of the chromatic index of signed graphs and proved that for every signed graph (G, σ) it holds that ∆(G) ≤ χ′(G,σ) ≤ ∆(G) + 1, where ∆(G) is the maximum degree of G and χ′ denotes its chromatic index. In general, the chromatic index of (G, σ) depends on both the underlying graph G and the signature σ. In the paper we study graphs G for which χ′(G, σ) does not depend on σ. To this aim we introduce two new classes of graphs, namely 1± and 2±, such that graph G is of class 1± (respectively, 2±) if and only if χ′(G, σ) = ∆(G) (respectively, χ′(G, σ) = ∆(G) + 1) for all possible signatures σ. We prove that all wheels, necklaces, complete bipartite graphs Kr,t with r ̸= t and almost all cacti graphs are of class 1±. Moreover, we give sufficient and necessary conditions for a graph to be of class 2±, i.e. we show that these graphs must have odd maximum degree and give examples of such graphs with arbitrary odd maximum degree bigger than 1.

  • Editorial, SI EATA2023
    • Piotr Jaskuła
    • Adam Zofka
    2023 Full text Road Materials and Pavement Design

    The European Asphalt Technology Association (EATA) is an organisation of leading European engineers and scientists involved in the asphalt material research. Every two years, the EATA celebrates its international pavement conference, with the aim of disseminating the key advances in scientific knowledge related to asphalt materials and technologies, and to encourage the transfer and application of this knowledge worldwide. Since the first event strictly selected papers are also published in a Special Issue of Road Material and Pavement Design Journal (RMPD) journal.

  • Edu Inspiracje WZiE: Postawione na głowie, czyli słów kilka o odwróconym nauczaniu
    • Marzena Grzesiak
    • Alina Guzik
    2023 Pismo PG

    Odwrócone nauczanie jest znane od dawna, ale jego współczesne zastosowanie datuje się na rok 2012, kiedy pojawiła się publikacja Bergmann’a i Saams. Pilotażowe wdrożenie tej metody zostało zrealizowane dla formie przedmiotu realizowanego w języku angielskim Modelowanie procesów biznesowych, skierowanego do studentów Politechniki Gdańskiej. Wśród zasobów udostępnionych przed zajęciami najczęściej wykorzystywano pliki PDF (zawierające opisy i zrzuty ekranowe danego zagadnienia) oraz filmy. Na podstawie opinii studentów oraz doświadczeń innych nauczycieli opisanych w literaturze, opracowane zostaną rekomendacje dla przeprojektowania kursu, z zachowaniem zasad metody odwróconego uczenia się.

  • Edu Inspiracje WZiE: Sztuczna inteligencja w edukacji. Czy strach ma wielkie oczy?
    • Karol Flisikowski
    • Alina Guzik
    2023 Full text Pismo PG

    Na dzień dzisiejszy bardzo trudno jest odróżnić treści pisane przez człowieka od tych generowanych przez AI, a najsmutniejsze jest to, że wszyscy, którzy używają pożyczonej inteligencji w nadmiarze, pozbawiają się okazji do uczenia i rozwoju. W rezultacie życie staje się łatwiejsze, ale mądrości jakby ubywa. W artykule dokonano krytycznego przeglądu narzędzi i algorytmów opartych o sztuczną inteligencję wspierający procesy edukacyjne.

  • Edukacja matematyczna na poziomie akademickim na kierunkach ścisłych i technicznych w dobie technologii mobilnych i sztucznej inteligencji
    • Anita Dąbrowicz-Tlałka
    2023 Full text e-mentor

    Rozwój technologii oraz rozwiązań bazujących na sztucznej inteligencji daje szansę pomocy nauczycielom i uczniom w rozwoju i poprawianiu wyników nauczania i uczenia się. Wszystko wskazuje na to, że narzędzia takie jak ChatGPT wkrótce staną się akceptowaną częścią zestawu narzędzi technologicznych. Musimy tylko nauczyć się, jak bezpiecznie i optymalnie z nich korzystać. Stosowanie technologii cyfrowej w edukacji matematycznej na poziomie akademickim jest ogromnym wyzwaniem. Z jednej strony mamy do dyspozycji wiele narzędzi, z których często sprawniej korzystają uczący się niż nauczyciele, a z drugiej strony deficyty wiedzy i umiejętności matematycznych kandydatów na studia wymagają wprowadzania wielu zmian w programach realizowanych w czasie zajęć. W przypadku edukacji matematycznej na kierunkach ścisłych i technicznych powinno to skłaniać do działań związanych z analizą stosowanych metod edukacyjnych oraz do wypracowania efektów uczenia się pozwalających studentom nie tylko na sprawne poruszanie się w cyfrowym świecie, ale i na jego współtworzenie. W artykule przedstawiono wybrane wyniki badań ankietowych przeprowadzonych wśród studentów pierwszego roku studiów inżynierskich związanych z wykorzystywaniem aplikacji i oprogramowania wspierającego edukację matematyczną. Pokazano również przykłady e-technologii stosowanych do uczenia się i rozwiązywania zadań, wskazano na ich możliwości oraz zagrożenia, jakie mogą stwarzać. Zasygnalizowano też konieczność modyfikacji programów i metod nauczania matematyki na poziomie akademickim pozwalających studentom na osiąganie efektów uczenia się z optymalnym wykorzystaniem technologii.

  • Efekty docierania jednotarczowego ceramiki Al2O3 narzędziem z poliamidu PA2200 wykonanym metodą selektywnego spiekania laserowego
    • Dawid Zieliński
    2023 Full text

    Przedmiot badań niniejszej rozprawy doktorskiej stanowi analiza procesu docierania jednotarczowego powierzchni płaskich z wykorzystaniem spiekanych z proszku poliamidowego metodą selektywnego spiekania laserowego prototypowych narzędzi ściernych. Tarcze docierające zbudowane zostały z niezależnych segmentów ściernych tworzących płaską powierzchnię czynną narzędzia przeznaczoną do docierania materiałów metalowych i niemetalowych, w tym ceramiki technicznej. W pracy zaprezentowano efekty technologiczne uzyskane w wyniku przeprowadzonych serii badań eksperymentalnych docierania ceramiki technicznej Al2O3 i dotyczących m.in. wielkości ubytku materiałowego, wartości parametrów chropowatości i falistości powierzchni, wydajności procesu obróbki, a także kształtu i wielkości zużycia narzędzi. Dokonano ponadto oceny istotności statystycznej różnic efektów technologicznych uzyskiwanych w poszczególnych seriach badań eksperymentalnych. Analizowano wpływ zmiennych wielkości wejściowych wraz z oceną istotności statystycznej oddziaływania i ich interakcji na wybrane wielkości wyjściowe. Wyznaczono modele matematyczne wybranych efektów docierania oraz dokonano ich oceny i walidacji. Porównanie rezultatów obróbkowych z wybranymi narzędziami ściernymi stosowanymi w technologii docierania oraz szlifowania z kinematyką docierania wskazało na duży potencjał oraz użyteczność opracowanych narzędzi.

  • Efektywność skrępowania betonu w grubościennych słupach typu Concrete-Filled Steel Tube o przekroju kołowym
    • Marcin Abramski
    • Piotr Korzeniowski
    • Jarosław Kondrat
    2023 Full text Materiały Budowlane

    W słupach typu CFST w stanie granicznym dochodzi do zwiększenia wytrzymałości betonu rdzenia na skutek jego skrępowania. Zaistnienie tego zjawiska zależy od wielu czynników. Jednym z najważniejszych z nich jest sztywność obwodowa płaszcza stalowego. Jej wpływ na efektywność wzrostu wytrzymałości betonu rdzenia przebadano eksperymentalnie na grupie 48 grubościennych słupów CFST. Wykazano, że nadmierne zwiększanie grubości płaszcza słupa CFST nie przekłada się na wzrost jego nośności sprowadzonej. Jest wręcz przeciwnie: następuje jej spadek. Znacznie lepsze wykorzystanie pozytywnego wpływu skrępowania betonu rdzenia można osiągnąć z zastosowaniem rur cienkościennych niż grubościennych.

  • Effect of Arc Strikes on High Strength Low Alloy Steels Welded by SMAW
    • Dariusz Fydrych
    • Przemysław Raczko
    • Aleksandra Świerczyńska
    • Michał Landowski
    • Adrian Wolski
    • Grzegorz Rogalski
    2023 Full text Advances in Science and Technology Research Journal

    Wet welding with covered electrodes (Shielded Metal Arc Welding – SMAW) is the most commonly used method of carrying out welding repair works in a water environment. Limited visibility and the inability to move freely under water result in an increased risk of formation of welding imperfections such as lack of fusion, lack of penetration and arc strikes. The work focused on changes in the properties and structure of steel subjected to the impact of short (0.2 s) arc ignitions generated by covered electrodes in air and under water for three high strength steel grades: S460N, S460M and S500MC. Visual tests, macroscopic and microscopic metallographic tests, microhardness measurements and diffusible hydrogen content in deposited metal determination were performed. A significant influence of the environment on changes in the morphology and microhardness of steel in the vicinity of arc strikes was found. The microhardness of the areas covered by the rapid thermal cycle caused by SMAW increased from 200–230 HV0.5 to 400–500 HV0.5 depending on the steel grade. The presence of welding imperfections: cavities and cracks were detected. The susceptibility of all steel grades subjected to short thermal cycles to cracking was confirmed by the results of measurements of the diffusible hydrogen content: 38.6 ml/100 g and 84.5 ml/100 g for air and water environment, respectively. No influence of changes in the welding current on the behavior of the material in the tested conditions was found. The conducted research shows that leaving arc strikes on the structure may have serious consequences and cause a failure.

  • Effect of austempering temperature on microstructure and cyclic deformation behaviour of multiphase low-carbon steel
    • X. Y. Long
    • Ricardo Branco
    • Wojciech Macek
    • Reza Masoudi Nejad
    • Grzegorz Lesiuk
    • Shun-Peng Zhu
    • A. M. Amaro
    2023 Full text Archives of Civil and Mechanical Engineering

    This paper examined the cyclic deformation behaviour of multiphase low-carbon steel that was subjected to austempering heat treatments at four temperatures (190 °C, 230 °C, 275 °C, and 315 °C) below the martensite start temperature (Ms = 353 °C). The tests were conducted at room temperature, under fully reversed strain-controlled conditions, with strain amplitudes in the range 0.5–1.0%. The microstructure was observed by transmission electron microscopy, and the fracture surfaces were examined by scanning electron microscopy. The steel had a bainite/martensite microstructure, with increasing bainite content for higher austempering temperatures. Irrespective of the tested conditions, it strain-hardened during the first two cycles and then, strain-softened until failure. The austempering temperature did not significantly affect the stress-based, strain-based and energy-based relationships. However, lower austempering temperatures slightly improved the fatigue performance.

  • Effect of bending-torsion on fracture and fatigue life for 18Ni300 steel specimens produced by SLM
    • Wojciech Macek
    • Reza Masoudi Nejad
    • Shun-Peng Zhu
    • Jarosław Trembacz
    • Ricardo Branco
    • José Domingos Costa
    • J.a.m. Fereira
    • Carlos Capela
    2023 MECHANICS OF MATERIALS

    In this study, different fracture surfaces caused by fatigue failure were generated from 18Ni300 steel produced by selective laser melting (SLM). Hollow round bars with a transverse hole were tested under bending-torsion to investigate the crack initiation mechanisms and fatigue life. Next, the post-failure fracture surfaces were examined by optical profilometer and scanning electron microscope. The focus is placed on the relationship between the fatigue features (e.g., bending-torsion ratio, fatigue crack initiation angles, and fatigue life) and the fracture surface topography parameters (e.g., height parameter Sx, volume parameters Vx, maximal pit and valley angles). The analysis was carried out using the entire fracture surface of the tested specimens. It was found that the decrease of the shear stress level significantly reduces the value of the fracture surface parameters. A fatigue life prediction model based on both the surface topography values and the applied load was proposed. Fatigue life predictions for different loading ratios agreed well with the experimental results and were slightly better than those of other existing models. The proposed model can be helpful for post-mortem analysis of engineering components sub-jected to multiaxial fatigue.

  • Effect of crystallinity on structural, thermal, and in vitro dissolution properties of Na2O-CaO-Nb2O5/MgO-P2O5 glass-ceramics
    • Natalia Wójcik
    • Stefania Wolf
    • Jakub Karczewski
    • Jacek Ryl
    • Sharafat Ali
    2023 JOURNAL OF THE EUROPEAN CERAMIC SOCIETY

    The impact of the crystallinity on structural, thermal, and in vitro dissolution properties were examined for Na2O- CaO-Nb2O5/MgO-P2O5 glasses/glass-ceramics. Glass-ceramics were synthesized via a spontaneous crystallization process. The Nb content in the materials increased with melting temperature, furthermore, the crystallinity is proportional to the Nb content. The presence of crystalline niobates and phosphates is confirmed by FTIR analysis which is consistent with XRD. The FTIR results indicate that the phosphate network is built of different proportions of Q2, Q1, and Q0 units, depending on the amount and type of crystalline phase. Most of the samples show an improvement in thermal stability. The in vitro dissolution test showed that the highest mass loss for most of the samples occurred during the first 6 days of immersion in the PBS solution. The presence of small phosphate crystals favors the deposition of hydroxyapatite on samples’ surfaces while the larger niobate crystals dissolve more readily.

  • Effect of dendrimer-based interlayers for enzyme immobilization on a model electrochemical sensing system for glutamate
    • Marcin Urbanowicz
    • Kamila Sadowska
    • Bartłomiej Lemieszek
    • Agnieszka Paziewska-Nowak
    • Anna Sołdatowska
    • Marek Dawgul
    • Dorota G. Pijanowska
    2023 BIOELECTROCHEMISTRY

    In this paper, we discuss dendrimer usage in enzyme-based electrochemical biosensors, particularly with respect to biomolecule loading on the sensing surface. A novel approach to design bioactive layers with immobilized enzymes for electrochemical biosensors using the surface plasmon resonance (SPR) method in combination with electrochemical impedance spectroscopy was presented. The gold surface was modified with linear linkers (various mercaptoalkanoic acids and aminoalkanethiols) and poly(amidoamines) dendrimers from the first- to fifth-generation. The best functionalization procedure was established by detailed SPR studies and transferred onto gold electrodes to electrochemically examine the model enzymatic reaction catalysed by glutamate oxidase. In the case of the chronoamperometric method, the determined sensitivity was 3.36±0.08 μA∙mM-1 , and the low limit of detection (LOD) was 1.52 μM. Comparing the sensitivity and LOD obtained for CV measurements, the values of these parameters were 2.5 times higher and 4 times lower, respectively, for the fourth-generation dendrimer-based biosensor and the biosensor with a linear linker. The positive impact of the dendrimer interlayer on the long-term enzyme activity was also confirmed. The research results indicate the possibility of a significant increase in the sensor response using the dendrimer itself without enriching it with electrochemical components.

  • Effect of hybrid modification by ceramic layer formation in MAO process and laser remelting on the structure of titanium bio-alloy Ti13Nb13Zr
    • Joanna Sypniewska
    • Marek Szkodo
    • Beata Majkowska-Marzec
    • Aleksandra Mielewczyk-Gryń
    2023 CERAMICS INTERNATIONAL

    To improve the biological properties of titanium alloy Ti13Nb13Zr, hybrid modifications involving micro-arc oxidation (MAO) and Nd: YAG laser remelting were carried out in two combinations. The first consisted of laser modification before the production of the ceramic layer by the micro-arc oxidation process, and the second combination involved Nd: YAG laser modification after the MAO process. The creation of developed surface morphologies on titanium alloys used in implant manufacturing is currently a widely discussed trend. The modifications used by the authors offer the possibility of obtaining a porous, wettable surface with altered nanohardness. To investigate the structural properties of the obtained hybrid Nd: YAG-MAO and MAO-laser Nd: YAG modifications, the structure roughness tests were performed with a suitable apparatus and atomic force microscope (AFM) and available software. The surface wettability was evaluated and the surface of the modified Ti13Nb13Zr alloy was subjected to evaluation using a scanning electron microscope (SEM), and an optical microscope. Using available software, chemical composition analysis, porosity analysis, and, adhesion analysis were performed. Based on the tests carried out, the possibility of carrying out hybrid modification in various combinations was demonstrated. The presence of Na+ and Ca2+ ions was demonstrated for samples in the combination of laser modification and MAO modification, which is important for biomedical reasons. Each modification allowed changing of the nanohardness, wettability, and roughness in the direction expected, required from biomedical materials. This paper presents an innovative approach to the use of two modifications one using the effect of heat on the matrix and the other focused on the formation of a ceramic coating. Currently, hybrid modifications are desirable in that they allow them to interact positively with each other.

  • Effect of Laser Treatment on Intrinsic Mechanical Stresses in Titanium and Some of Its Alloys
    • Magdalena Jażdżewska
    • Michał Bartmański
    • Andrzej Zieliński
    • Dominika Kwidzińska
    2023 Full text Applied Sciences-Basel

    Laser surface treatment conducted at different power levels is an option to modify titanium bone implants to produce nano- and microtopography. However, such processing can lead to excess mechanical stress within the surface layer. This research aims to calculate the level of such residual stresses after the surface processing of Ti grade IV, Ti15Mo, and Ti6Al7Nb alloys with an Nd:YAG laser. Light and scanning electron microscopies (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD), optical profilography, and nano-indentation tests were applied to characterize the surface zone. The laser processing resulted in a distinct surface pattern and the formation of remelted zones 66–126 μm thick, with roughness values ranging between 0.22 and 1.68 μm. The mechanical properties were weakly dependent on the material composition. The residual stresses caused by the laser treatment were moderate, always tensile, increasing with loading, and was the highest for the Ti15Mo alloy.

  • Effect of Microplastics Pollution on Hydrogen Production from Biomass: A Comprehensive Review
    • Zhila Honarmandrad
    • Zhila Honarmandrad
    • Jacek Gebicki
    2023 Full text INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH

    Hydrogen production from biomass and organic wastes is considered as a potential alternative energy source and is known as a clean and CO2-free fuel energy carrier. H2 is considered very promising among the other energy sources; therefore, the effective conversion of biomass and organic solid waste to this secondary energy source is urgently sought. As a result, it is of importance to assess the impact of the existence of microplastics (MPs) pollution in biomass during its fermentation. It was found that, besides the number of plastic particles present in biomass, the size of them plays the most important role in the yield of hydrogen. While plastics in nanoparticle sizes always suppress the production of H2, depending on their concentration, MPs may increase or reduce it. For example, the presence of 60 particles/L of micrometer-sized polyethylene terephthalate reduces hydrogen production by 30%, while 200 particles of it yields 63.6% more hydrogen. This Review examines all available literature on the effects of the presence of various MPs on biohydrogen production.

  • Effect of oxidation and in vitro intestinal hydrolysis on phospholipid toxicity towards HT29 cell line serving as a model of human intestinal epithelium
    • Karol Parchem
    • Monika Baranowska
    • Anna Kościelak
    • Ilona Kłosowska-Chomiczewska
    • Maria Rosario Domingues
    • Adam Macierzanka
    • Agnieszka Bartoszek-Pączkowska
    2023 Full text FOOD RESEARCH INTERNATIONAL

    Oxidation of food-derived phospholipids (PLs) can influence nutrient digestion and induce oxidative stress in gastrointestinal epithelium. In this study, hen egg yolk PL fraction was used to evaluate the effect of lipoxygenase (LOX)-induced PL oxidation on the rate of PL hydrolysis catalyzed by pancreatic phospholipase A2 (PLA2) in the presence of bile salts (BSs). Then, PL/BS solutions containing native or oxidized PLs were used in in vitro intestinal digestion to assess the effect of PL oxidation and hydrolysis on the toxicity towards HT29 cell line. Based on the obtained results, we suggest that hexanal and (E)-2-nonenal, formed by the decomposition of PL hydroperoxides, inhibited PLA2 activity. The cell exposure to simulated intestinal fluid (SIF) containing BSs decreased HT29 cell viability and significantly damaged cellular DNA. However, the genotoxic effect was reversed in the presence of all tested PL samples, while the protective effect against the BS-induced cytotoxicity was observed for native non-hydrolyzed PLs, but was not clearly visible for other samples. This can result from an overlap of other toxic effects such as lipotoxicity or disturbance of cellular redox homeostasis. Taking into account the data obtained, it was proposed that the PLA2 activity decline in the presence of PL oxidation products may be a kind of protective mechanism against rapid release of oxidized FAs characterized by high cytotoxic effect towards intestinal epithelium cells.

  • Effect of processing parameters on the cyclic behaviour of aluminium friction stir welded to spark plasma sintered aluminium matrix composites with bimodal micro-and nano-sized reinforcing alumina particles
    • Behzad Sadeghi
    • Pasquale Cavaliere
    • Aleksandra Laska
    • Angelo Perrone
    • Gianni Blasi
    • Arun Gopinathan
    • M. Shamanian
    • F. Ashrafizadeh
    2023 MATERIALS CHARACTERIZATION

    Understanding the cyclic behaviour of Alumina reinforced Aluminium composites (Al-A2O3) was of critical importance, for their further application in the different industrial sectors. The present study is focussing on the cyclic behaviour of the Al-Alumina nanocomposite produced through the combination of spark plasma sintering (SPS) method and friction stir welding (FSW). The added Alumina with total content of 10% is the combination of nano and micro-sized particles and its ratio differ for each sample. The microstructure of the SPSed samples is characterized using optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The microstructure of the processed composite samples is characterized and its mechanical behaviour is studied. Microstructural studies showed that nano sized particles of Alumina were mostly distributed along the grain boundaries and inside the grains, while micron-sized ones mostly settled on the grain boundaries. In addition, the hardness and tensile properties of the produced samples are analysed concerning the reinforcement size and the percentage of nanoparticles addition. The obtained results reveal that the mechanical and fatigue properties of the nanocomposite materials mainly depend on the material properties at the initial stage and the applied conditions of friction stir welding such as rotating speed and movement speed. The facture surface of the nanocomposites revealed a combined ductile–brittle fracture mode with finer dimples with emphasis on the pronounced role of nano-metric dispersoids.

  • Effect of pulse laser treatment at different process variables on mechanical behavior of carbon nanotubes electrophoretically deposited on titanium alloy
    • Beata Majkowska-Marzec
    • Joanna Sypniewska
    • Kacper Staszewski
    2023 Acta of Bioengineering and Biomechanics

    Purpose: Titanium and its alloys are widely used as biomaterials for long-term implants, but they are usually surface-modified due to their weak bioactivity and wear resistance. Laser processing was used to modify the surface layer, and elemental carbon was a component of the deposited coatings. This research aims to use a combination of both methods based on preliminary electrophoretic deposition of multi-wall carbon nanotubes (MWNCTs) followed by pulse laser treatment. Carbon nanotubes were chosen due to their mechanical and chemical stability as well as their tubular shape, resulting in enhanced mechanical properties of laser-modified layers. Methods: The pulse laser power and laser scanning speed were defined as variable process parameters. The microstructure, roughness Ra, nanohardness H, Young’s modulus E, and indent depth values were measured, and the H/E, H 3 /E2 , and relative changes of all these values in comparison to MWCNTs-coated and non-coated surfaces, were calculated. Results: The obtained results show that the best mechanical properties of MWCNTs-coated and laser-treated specimens are obtained at a laser power of 900 W and laser feed of 6 mm/s. The observed relations can be explained considering processes occurring on the surface such as deposition of carbon nanotubes, melting and re-crystallization of the surface layer, formation and possible partial decomposition of titanium carbides, and associated changes in local chemical composition, phase composition, and a level of residual stresses beneath the surface. Conclusions: The developed process can substitute the time and money-consuming carbonization of titanium and its alloys.

  • Effect of Simultaneous Valve Closures in Hydraulic Piping Systems
    • Kamil Urbanowicz
    • Igor Haluch
    • Anton Bergant
    • Adam Deptuła
    • Paweł Śliwiński
    2023

    The paper investigates wave interference (between pressure waves) occurring in simple hydraulic systems. Water hammer was induced by simultaneous closure of three valves located at the reservoirs of a “Y” type hydraulic system. Numerical simulations were carried out with the help of the freeware computer package Allievi enabling the reader to replicate results in a direct manner. The influence of the following quantities has been tested: Reynolds number Re (laminar and turbulent flow), the length of the pipe arms (L1, L2, L3), the constant pipe internal diameter (Di = const.) and variable internal pipe diameters Di (D1 = D2 = D3). The results of the research showed how unwanted interferences between pressure waves may occur and thus increase the possibility of piping system damage. Further numerical investigations are sought in consideration of unsteady skin friction losses and viscoelastic pipe wall effects.

  • Effect of soil on the capacity of viscous dampers between adjacent buildings
    • Elif Cagda Kandemir
    • Robert Jankowski
    2023 Full text GRADEVINAR

    This study investigated the seismic pounding of two adjacent buildings considering soil–structure interaction (SSI). A comprehensive parametric study of buildings with different heights was performed to reveal the pounding-involved behaviour considering the soil effect. Wavelet transform has been conducted to gain insight into the differences in the frequency contents of the impact forces between fixed- and flexible-base adjacent structures. Linear viscous dampers (LVDs) between adjacent floors were used as pounding protection measures. The required supplemental damping ratio of the LVDs was determined through optimisation analysis under different soil types to verify the effect of the SSI on structural damping. Comparative results with and without SSI showed that incorporating the SSI worsens the pounding-involved responses during earthquakes.

  • Effect of temperature and composition on physical properties of deep eutectic solvents based on 2-(methylamino)ethanol – measurement and prediction
    • Bartosz Nowosielski
    • Marzena Jamrógiewicz
    • Justyna Łuczak
    • Agnieszka Tercjak
    • Dorota Warmińska
    2023 JOURNAL OF MOLECULAR LIQUIDS

    Novel deep eutectic solvents were synthesized using 2-(methylamino)ethanol as hydrogen bond donor with tetrabutylammonium bromide or tetrabutylammonium chloride or tetraethylammonium chloride as hydrogen bond acceptors. Mixtures were prepared at different molar ratios of 1:6, 1:8 and 1:10 salt to alkanolamine and then Fourier Transform Infrared Spectroscopy measurements were performed to confirm hydrogen bonds interactions between components. Moreover, thermal properties such as melting points and thermal stability of deep eutectic solvents were determined and described. Each of important physical properties, including densities, viscosities, refractive indices and sound velocities at the temperature range of 293.15–333.15 K and the pressure of 0.1 MPa, were measured and discussed. The effect of hydrogen bond acceptor to hydrogen bond donor molar ratio, anion and length of alkyl chain for each synthesized salt according to their properties was evaluated. Additionally, the experimental values of each physicochemical parameter were compared with the predicted ones calculated using models recommended in literature. The main aim of this work was to assess the suitability of existing mathematical models for predicting the physicochemical properties of novel alkanolamine-based DESs. Empirical correlations for approximating phase behaviour or flow properties for DES systems are used in many procedures for design materials used of carbon-dioxide capture purposes. The obtained results indicate that in the case of deep eutectic solvents based on 2-(methylamino)ethanol, in the absence of any experimental data, the best models for density prediction are the bonding group interaction contribution method and the group contribution model. For modelling of the refractive index it has been confirmed that a method based on the critical properties is the most satisfying. However, for the viscosity and speed of sound, the absolute average relative deviations for the methods based on critical properties exceed the measurement uncertainties found in practice. Therefore, they do not seem suitable for an accurate estimation of these properties for deep eutectic solvents based on 2-(methylamino)ethanol.

  • Effect of water salinity on properties of multipass underwater wet manual metal arc welded joints
    • Jacek Tomków
    • Dariusz Fydrych
    • Jerzy Łabanowski
    2023 Full text Welding in the World

    The weldability of steel under the water is limited due to the influence of the environment. Water causes limited visibility, presence of the residual stresses, increasing the cooling rate, and increasing the diffusible hydrogen content in deposited metal, leading to the formation of brittle microstructures in heat-affected zone (HAZ). The paper presents the results of mechanical properties testing of S420G2+M steel welded joints made with covered electrodes in the water with salinity values: 0‰, 7.5‰, and 35‰. The non-destructive tests: ultrasonic (UT) and radiographic (RT), and destructive tests: Vickers HV10 measurements, Charpy impact, and bending and metallographic macro- and microscopic tests were performed. Moreover, the diffusible hydrogen content in deposited metal by the mercury method was measured. It was observed that water salinity has an influence on the stability of the welding arc and the properties of joints. In particular, it was found that increasing the water salinity provides to: decreasing the hardness of HAZ (from 211 HV10 to 193 HV10), increasing the impact strength (from 82.5 to 101.3 J/cm2). Additionally, a slight increase in the diffusible hydrogen content in deposited metal (up to 65 ml/100g) was observed. The number of microcracks in the joints decreased with increasing the water salinity.

  • Effect of wet Hydrogen Sulfide on Carbon Steels Degradation in Refinery Based on Case Study
    • Juliusz Orlikowski
    • Agata Jażdżewska
    • İlyas Uygur
    • Radosław Gospoś
    • Tomasz Olczak
    • Kazimierz Darowicki
    2023 Full text ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING

    Material degradation caused by wet hydrogen sulfide (Wet H2S) is one of the major issues in refineries. Carbon steel is the main construction material used in refineries and is subjected not only to thickness loss but the hydrogen is the major concern. H2S leads to high atomic hydrogen penetration in steel which causes degradation in the form of blistering and/or cracking (HIC/SOHIC) and stress cracking in the area of welds and heat affected zones. Mechanism is unusually dangerous due to high difficulty of threat assessment, which is mostly based on ultrasonic measurements or calculations based on the API standards. This research is based on evaluation of the real threat of wet H2S degradation based on examination of construction materials after 41 years of exploitation in refinery. The comparison of the theoretical calculation based on API standards and experience of the degradation of the real objects was characterized. Laboratory measurements include mechanical tests involving the elongation in the function of tensile stress and deformation, with analysis of material hardness and gas chromatography analysis. The results are complemented by studies of the chemical composition of the streams and analytical studies of the hydrogen content in the material obtained by the gas chromatography method. The tests showed compliance of the standard analysis of the corrosion risk with the laboratory tests performed on the real samples. Research leads to indication of the destructive methods which can be used on the materials obtained during scheduled material replacements or installation modernizations.

  • Effective Air Quality Prediction Using Reinforced Swarm Optimization and Bi-Directional Gated Recurrent Unit
    • Sasikumar Gurumoorthy
    • Aruna Kumari Kokku
    • Przemysław Falkowski-Gilski
    • Parameshachari Bidare Divakarachari
    2023 Full text Sustainability

    In the present scenario, air quality prediction (AQP) is a complex task due to high variability, volatility, and dynamic nature in space and time of particulates and pollutants. Recently, several nations have had poor air quality due to the high emission of particulate matter (PM2.5) that affects human health conditions, especially in urban areas. In this research, a new optimization-based regression model was implemented for effective forecasting of air pollution. Firstly, the input data were acquired from a real-time Beijing PM2.5 dataset recorded from 1 January 2010 to 31 December 2014. Additionally, the newer real-time dataset was recorded from 2016 to 2022 for four Indian cities: Cochin, Hyderabad, Chennai, and Bangalore. Then, data normalization was accomplished using the Min-Max normalization technique, along with correlation analysis for selecting highly correlated variables (wind direction, temperature, dew point, wind speed, and historical PM2.5). Next, the important features from the highly correlated variables were selected by implementing an optimization algorithm named reinforced swarm optimization (RSO). Further, the selected optimal features were given to the bi-directional gated recurrent unit (Bi-GRU) model for effective AQP. The extensive numerical analysis shows that the proposed model obtained a mean absolute error (MAE) of 9.11 and 0.19 and a mean square error (MSE) of 2.82 and 0.26 on the Beijing PM2.5 dataset and a real-time dataset. On both datasets, the error rate of the proposed model was minimal compared to other regression models.

  • Effective assessment of biopolymer-based multifunctional sorbents for the remediation of environmentally hazardous contaminants from aqueous solutions
    • Shahid Nawaz
    • Andleeb Tabassum
    • Sara Muslim
    • Tayyaba Nasreen
    • Ausra Baradoke
    • Tak H. Kim
    • Grzegorz Boczkaj
    • Teofil Jesionowski
    • Muhammad Bilal
    2023 CHEMOSPHERE

    Persistent contaminants in wastewater effluent pose a significant threat to aquatic life and are one of the most significant environmental concerns of our time. Although there are a variety of traditional methods available in wastewater treatment, including adsorption, coagulation, flocculation, ion exchange, membrane filtration, co-precipitation and solvent extraction, none of these have been found to be significantly cost-effective in removing toxic pollutants from the water environment. The upfront costs of these treatment methods are extremely high, and they require the use of harmful synthetic chemicals. For this reason, the development of new technologies for the treatment and recycling of wastewater is an absolute necessity. Our way of life can be made more sustainable by the synthesis of adsorbents based on biomass, making the process less harmful to the environment. Biopolymers offer a sustainable alternative to synthetic polymers, which are manufactured by joining monomer units through covalent bonding. This review presents a detailed classification of biopolymers such as pectin, alginate, chitosan, lignin, cellulose, chitin, carrageen, certain proteins, and other microbial biomass compounds and composites, with a focus on their sources, methods of synthesis, and prospective applications in wastewater treatment. A concise summary of the extensive body of knowledge on the fate of biopolymers after adsorption is also provided. Finally, consideration is given to open questions about future developments leading to environmentally friendly and economically beneficial applications of biopolymers.

  • Effective Equations for the Optimum Seismic Gap Preventing Earthquake-Induced Pounding between Adjacent Buildings Founded on Different Soil Types
    • Mahmoud Miari
    • Robert Jankowski
    2023 Full text Applied Sciences-Basel

    The best approach to avoid collisions between adjacent structures during earthquakes is to provide sufficient spacing between them. However, the existing formulas for calculating the optimum seismic gap preventing pounding were found to provide inaccurate results upon the consideration of different soil types. The aim of this paper is to propose new equations for the evaluation of the sufficient in-between separation gap for buildings founded on different soil conditions. The double-difference formula has been taken into account in this study. The seismic gap depends on the correlation factor and on the top displacements of adjacent buildings. The correlation factor depends on the ratio of the periods of adjacent buildings (smaller period to larger period). The modification of the correlation factor has been introduced for buildings founded on five different soil types. Five soil types were taken into account in this study, as defined in the ASCE 7-10 code, i.e., hard rock, rock, very dense soil and soft rock, stiff soil, and soft clay soil. The normalized root mean square errors have been calculated for the proposed equations. The results of the study indicate that the error ranges between 2% and 14%, confirming the accuracy of the approach. Therefore, the proposed equations can be effectively used for the determination of the optimum seismic gap preventing earthquake-induced pounding between buildings founded on different soil types.

  • Effectiveness of various types of coating materials applied in reinforced concrete exposed to freeze–thaw cycles and chlorides
    • Ginneth Millan Ramirez
    • Hubert Byliński
    • Maciej Niedostatkiewicz
    2023 Full text Scientific Reports

    This study assesses the durability of coated and uncoated concrete surfaces protected with four Different coating materials: water-soluble (BW), solvent-based (BR), mineral (MI), and epoxy (EP). The durability assessment includes evaluating the absorption rate of water, pull-of adhesion strength, and coating material thickness. Concrete samples were subjected to immersion in regular water and a 7% urea solution, followed by cyclic freezing and thawing. Furthermore, the diffusion of chloride ions in concrete was evaluated using the impressed voltage method, with the samples exposed to the aging process, immersed in a 3.5% NaCl solution. The results indicate that EP and BW coatings were significantly affected by the presence of urea and freeze–thaw cycles, resulting in a 43% and 47% reduction in pull-of adhesion strength, respectively. Notably, the MI-coated concrete samples exposed to urea solution and the freeze–thaw cycles exhibited a significant reduction in the absorption rate due to the accumulation of crystals on the coating surface, resulting in reduced porosity of the material.

  • Effects of Deck-Abutment Pounding on the Seismic Fragility Curves of Box-Girder Highway Bridges
    • Seyyed Amirhossein Moayyedi
    • Hossein Rezaei
    • Afshin Kalantari
    • Robert Jankowski
    2023 JOURNAL OF EARTHQUAKE ENGINEERING

    Earthquake-induced pounding in bridges is a complex contact phenomenon in which the dynamic responses of structures, including collisions between deck and abutments, are strongly related to structural properties and earthquake excitation. The goal of this study is to develop and compare the seismic fragility curves of overall system and individual components of regular and irregular box-girder highway bridges in two cases: with pounding and without pounding. For this purpose, four levels of altitudinal irregularity, ranging from regular to highly irregular, are considered. To extend the results for all bridges in the same class, different sources of uncertainties related to earthquakes, structural geometries, and material properties are taken into account. The analytical fragility curves have been developed based on nonlinear time history analyses in OpenSees finite element software for the cases with and without pounding effects. The process has been repeated for each two-, three-, and four-span classes at four irregularity levels. The fragility function parameters for the two cases with and without pounding have been compared for all classes considered in this study. Using fragility functions, this paper clarifies the interactive roles of irregularity and pounding between deck and abutments for seismic vulnerability of multi-span box-birder highway bridges. The results indicate that collisions often show an adverse effect on all structural components. It has also been observed that the detrimental effect of pounding on seismic fragility is more apparent in irregular bridges when compared with regular ones. In addition, the study introduces a conversion coefficient to clarify the effects of pounding on the fragility of bridge components and the overall system. This coefficient can be applied in both conventional analytical methods like static or simplified analysis and technical earthquake models like HAZUS, adjusting fragility values for pounding and irregularity effects.

  • Effects of Storing Flux-Cored Wires under Various Conditions
    • Aleksandra Świerczyńska
    • Michał Landowski
    • Adrian Wolski
    • Grzegorz Lentka
    • Dariusz Fydrych
    • Jerzy Łabanowski
    2023 Full text Biuletyn Instytutu Spawalnictwa w Gliwicach

    Welding processes involving the use of flux-cored wires are becoming increasingly popular, particularly in shipbuilding as well as in off-shore and civil engineering. The article presents characteristics of the welding process, its areas of application as well as advantages and disadvantages (e.g. necessity of ensuring appropriate conditions for the storage of filler metal wires). The satisfaction of quality-related requirements concerning welded joints necessitates controlling the quality of flux-cored wires as their condition (apart from welding conditions) is one of the most important factors affecting the welding process and the quality of joints. The analysis of related reference publications and individual study revealed that the storage of wires under conditions inconsistent with requirements specified by producers affects welding process stability and weld deposit properties. Visual tests (VT) tasked with assessing the quality of wire surface do not always provide sufficient information as regards the usability of filler metal wires in welding processes.

  • Effects of the Covid-19 travel restrictions on metropolises mobility: empirical evidence from the Tricity metropolis (Poland)
    • Krzysztof Grzelec
    • Katarzyna Hebel
    • Romanika Okraszewska
    • Olgierd Wyszomirski
    2023 Full text Prace Komisji Geografii Komunikacji PTG

    This paper aims to assess changes in mobility and modal shift caused by COVID-19 travel restrictions among the residents of Gdańsk Bay Metropolis (Poland). Measurement’s moments were assumed in periods differing in the level of restric- tions. The computer-assisted telephone interview (CATI) was carried out in November and December 2020. The results did not confirm the expected modal shift. However, significant changes in the number of trips between periods were observed. Restrictions in the first period of the pandemic resulted in a greater decrease in mobility than the restrictions at the end of the year. Moreover, significant associations were found between transport behaviour and place of residence. Nevertheless, pos- sible negative changes in the modal split after the pandemic ends should be counteracted by improving the quality of public transport services. As the most important attributes of public transport attracting passengers after the pandemic respondents recognized: high frequency of vehicles, low cost of travel, not overcrowded vehicles. However, some residents declared they will not use public transport regardless of service improvements. Consequently, to meet the objectives of sustainable mobility policy, it can be necessary to increase the share in the modal split of other sustainable modes of travel

  • Effects of thermal history on the performance of low-temperature solid oxide fuel cells with Sm0.2Ce0.8O2-δ electrolyte and LiNi0.81Co0.15Al0.04O2 electrodes
    • Sea-Fue Wang
    • Yi-Le Liao
    • Yung-Fu Hsu
    • Tsang Yu Weng
    • Piotr Jasiński
    2023 JOURNAL OF POWER SOURCES

    In this study, low-temperature solid oxide fuel cells with an ∼560 μm thick Sm0.2Ce0.8O2−δ (SDC) electrolyte and ∼890 μm thick LiNi0.81Co0.15Al0.04O2−δ (NCAL) electrodes are constructed and characterized under three experimental conditions. The cell with an NCAL cathode pre-reduced under an H2 atmosphere at 550 °C presents the best electrochemical performance. This is ascribed to facts that the reduction reaction generating Ni–Co alloy particles on the NCAL surface and partial reoxidation of Ni–Co to Ni(Co)O under an air atmosphere during subsequent experiments increase the triple-phase-boundary area, improve the catalytic activity for the oxygen reduction reaction, and cause a low polarization resistance (0.186 Ω cm2). Also, the reduction of the Ni foam–NCAL anode triggers the formation of H+/O2− bi-ionic SDC–Li2CO3–LiOH composite electrolytes. The LiOH–Li2CO3 melt permeates and densifies the electrolyte layer; this significantly increases the electrical conductivity of the electrolyte layer to 0.291 S cm−1 and lowers the ohmic resistance of the cell (0.170 Ω cm2). The Li2CO3–LiOH phases serve as electron-blocking layers to limit the electronic conductivity of the electrolyte layer. This induces a high open-circuit voltage of 1.024 V and a high maximum power density of 611.3 mW·cm−2.

  • Efficient optimization approaches for microwave assisted extraction of high-quality antioxidant compounds from Salvia officinalis L.: UHPLC-HRMS differential analysis of phenolic profiles obtained by ultrasound and microwave extraction
    • Hamza Moussa
    • Farid Dahmoune
    • Marika Mróz
    • Hocine Remini
    • Nabil Kadri
    • Sarah Hamid
    • Barbara Kusznierewicz
    2023 Sustainable Chemistry and Pharmacy

    The study aims to optimize MAE of total phenolic compounds (TPC) and antioxidant capacity from Salvia officinalis L. leaves using a definitive screening design (DSD) and I-optimal design. UHPLC-HRMS analysis was used to identify and compare the composition of MAE and UAE optimal extracts. The results showed that DSD and I-optimal design were successfully applied for the optimization of MAE targeting phenolics and other antioxidants from S. officinalis L. with the following optimum conditions: 60% ethanolic solvent, time of 4.75 min, power of 600 W, and L/S ratio of 50 mL g 1. The UHPLC-MS analysis results allowed the identification of more than 80 compounds, and the differential analysis indicated that the MAE yielded a higher level of 181 substance peaks, while the UAE yielded a higher level of 87 substance peaks. This study provides valuable information for selecting the appropriate extraction technique when targeting specific compounds.

  • Efficient parallel implementation of crowd simulation using a hybrid CPU+GPU high performance computing system
    • Jakub Skrzypczak
    • Paweł Czarnul
    2023 SIMULATION MODELLING PRACTICE AND THEORY

    In the paper we present a modern efficient parallel OpenMP+CUDA implementation of crowd simulation for hybrid CPU+GPU systems and demonstrate its higher performance over CPU-only and GPU-only implementations for several problem sizes including 10 000, 50 000, 100 000, 500 000 and 1 000 000 agents. We show how performance varies for various tile sizes and what CPU–GPU load balancing settings shall be preferred for various domain sizes among CPUs and GPUs of a high performance system with 2 Intel Xeon Silver multicore CPUs and 8 NVIDIA Quadro RTX 5000 GPUs. We then present how execution time depends on the number of agents as well as the number of CUDA streams used for parallel execution of several CUDA kernels. We discuss the design and implementation of an algorithm with CPU computational threads, GPU management threads, assignment of particular tasks to threads as well as usage of pinned memory and CUDA shared memory for maximizing performance.

  • Efficient uncertainty quantification using sequential sampling-based neural networks
    • Pavankumar Koratikere
    • Leifur Leifsson
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2023

    Uncertainty quantification (UQ) of an engineered system involves the identification of uncertainties, modeling of the uncertainties, and the forward propagation of the uncertainties through a system analysis model. In this work, a novel surrogate-based forward propagation algorithm for UQ is proposed. The proposed algorithm is a new and unique extension of the recent efficient global optimization using neural network (NN)-based prediction and uncertainty (EGONN) algorithm which was created for optimization. The proposed extended algorithm is specifically created for UQ and is called uqEGONN. The uqEGONN algorithm sequentially and simultaneously samples two NNs, one for the prediction of a nonlinear function and the other for the prediction uncertainty. The uqEGONN algorithm terminates based on the absolute relative changes in the summary statistics based on Monte Carlo simulations (MCS), or a given maximum number of sequential samples. The algorithm is demonstrated on the UQ of the Ishigami function. The results show that the proposed algorithm yields comparable results as MCS on the true function and those results are more accurate than the results obtained using space-filling Latin hypercube sampling to train the NNs.

  • Ekspertyza dotycząca stanu zachowania drzewostanu. Osiedle domów jednorodzinnych.
    • Maura Zaworska
    2023

    Badanie wpływu inwestycji na stan zachowania drzewostanu rosnącego w rejonie bezpośredniego oddziaływania prac budowlanych.

  • Ekspertyza naukowo-techniczna dotycząca analizy i oceny rozwiązań projektowych oraz aspektów wykonawczych posadowienia na kolumnach przemieszczeniowych FDC budynku usługowo-apartamentowego przy ul. Bulwar Gdański 9 w Szczecinie
    • Adam Krasiński
    • Andrzej Słabek
    2023

    Ustalenie przyczyn projektowych i wykonawczych wadliwej jakości kolumn fundamentowych do posadowienia budynku biurowo-mieszkalnego

  • Ekspertyza polegająca na wykonaniu analiz space syntax dla oddziału Onkologii w szpitalu w Gliwicach.
    • Weronika Dettlaff
    2023

    Ekspertyza dotyczy wykorzystania analizy syntaktycznej przestrzeni (space syntax analysis) w procesie planowania przestrzeni. Metoda ta pozwala prognozować wpływ konfiguracji przestrzennej na zachowanie użytkowników. Jest przydatna na każdym etapie planowania, zarówno w przypadku przestrzeni miejskich, jak i w budynkach. Miary syntaktyczne opisujące konfigurację przestrzenną umożliwiają opisanie i wyjaśnienie relacji przestrzennych oraz przewidywanie skutków decyzji projektowych. Mimo że metoda ta cieszy się dużą popularnością wśród zagranicznych urbanistów, socjologów, planistów, projektantów wnętrz i informatyków, w Polsce jest jeszcze mało znana i nie jest powszechnie stosowana. Dokument zawiera omówienie genezy analizy syntaktycznej przestrzeni, wyjaśnienie podstawowych pojęć z nią związanych oraz analizę przypadku jej stosowania w procesie planowania poprawy znajdowania drogi (wayfindingu) oraz poruszania się w Narodowym Instytucie Onkologii w Gliwicach.

  • Ekspertyza techniczna dotycząca przyczyn zawilgocenia ścian Katedry w Kwidzynie oraz wpływu zabudowy dwóch kwartałów mieszkalno-usługowych przy Katedrze realizowanych w latach 2010-2011 oraz 2018-2020 na stan zawilgocenia murów Katedry
    • Adam Krasiński
    • Michał Nitka
    • Andrzej Słabek
    2023

    Przedmiotem opracowania jest ekspertyza dotycząca przyczyn zawilgocenia ścian Katedry pw. św. Jana Ewangelisty w Kwidzynie oraz wpływu zabudowy dwóch kwartałów mieszkalno-usługowych przy katedrze, zrealizowanych w latach 2010-2011 oraz 2018-2020 na stan zawilgocenia murów budynku katedry. Ekspertyza swoim zakresem obejmuje ocenę zawilgocenia murów oraz ścian na zewnątrz oraz wewnątrz katedry, jak również wskazuje potencjalne przyczyny oraz czynniki wpływające na taki stan rzeczy np. zmiana stosunków wodnych po zrealizowaniu zabudowy części obszaru Starego Miasta. W ekspertyzie przedstawiono także zalecenia mające na celu wyeliminowanie lub znaczne ograniczenie gromadzenia się wody bezpośrednio przy fundamentach oraz jej wnikania w mury katedry. Opracowanie wykonano na podstawie analiz dostępnych dokumentacji oraz opracowań tj. głównie wcześniejszych ekspertyz, przekazanych przez Zamawiającego. Ponadto podczas odbytych dwóch wizji lokalnych przeprowadzono oględziny oraz nieinwazyjne pomiary wilgotnościowe murów katedry, jak również dokonano wierceń podłoża gruntowego w pobliżu katedry oraz pomiarów geodezyjnych części terenu wokół celem określenia spadów terenu i kierunków spływu wód opadowych.

  • Eksperymentalna analiza wpływu ruchu posuwisto-zwrotnego i obrotowego oraz miejscowych zmian geometrii na skuteczność wypierania cieczy wiertniczych z przestrzeni pierścieniowej
    • Paweł Szewczuk
    2023 Full text

    Rozprawa przedstawia analizę wpływu ruchu kolumny rur stosowanego w wiertnictwie oraz miejscowych zmian geometrii przestrzeni pierścieniowej na skuteczność procesu wypierania się cieczy. Jest to pierwsze badanie w otwartej literaturze omawiające te czynniki, w którym opisano wyniki eksperymentów na dedykowanym stanowisku badawczym. W pracy omówiony został wpływ węglowodorów na współczesną cywilizację, jak również wpływ skuteczności procesu wypierania cieczy wiertnicznych na powodzenie całej operacji ich pozyskiwania. W dalszej części omówione zostały kroki milowe w zrozumieniu procesu wypierania się cieczy wiertniczych jak i podstawowe zależności matematyczne definiujące ruch cząsteczek płynu. W rozdziale 3 postawione zostały cztery tezy nawiązujące do tematu rozprawy, które w rozdziale 4 zostały potwierdzone opisanymi wynikami eksperymentalnymi. Udowodniono: - zwiększenie wydajności wypierania cieczy z przestrzeni pierścieniowej przy implementacji ruchu posuwisto-zwrotnego; - zwiększenie wydajności procesu przy implementacji ruchu obrotowego; - dalsze zwiększenie wydajności procesu przy implementacji ruchu posuwisto-zwrotnego i obrotowego; - zmniejszenie wydajności procesu w sąsiedztwie zwężeń otworu. Dodatkowo, negatywny wpływ zwężeń został potwierdzony analizą wyników płytkich otworów eksperymentalnych jak i otworów komercyjnych przedstawioną w rozdziale 5.

  • Elastic scattering of electrons by water: An ab initio study
    • Francesca Triggiani
    • Tommaso Morresi
    • Simone Taioli
    • Stefano Simonucci
    2023 Full text Frontiers in Materials

    In this work we devise a theoretical and computational method to compute the elastic scattering of electrons from a non-spherical potential, such as in the case of molecules and molecular aggregates. Its main feature is represented by the ability of calculating accurate wave functions for continuum states of polycentric systems via the solution of the Lippmann-Schwinger equation, including both the correlation effects and multi-scattering interference terms, typically neglected in widely used approaches, such as the Mott theory. Within this framework, we calculate the purely elastic scattering matrix elements. As a test case, we apply our scheme to the modelling of electron-water elastic scattering. The Dirac-Hartree-Fock self-consistent field method is used to determine the non-spherical molecular potential projected on a functional space spanned by Gaussian basis set. By adding a number of multi-centric radially-arranged s-type Gaussian functions, whose exponents are system-dependent and optimized to reproduce the properties of the continuum electron wave function in different energy regions, we are able to achieve unprecedented access to the description of the low energy range of the spectrum (0.001 < E < 10 eV) up to keV, finding a good agreement with experimental data and previous theoretical results. To show the potential of our approach, we also compute the total elastic scattering cross section of electrons impinging on clusters of water molecules and zundel cation. Our method can be extended to deal with inelastic scattering events and heavy-charged particles.