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Politechniki Gdańskiej

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  • Impact of Temperature and Nanoparticle Concentration on Turbulent Forced Convective Heat Transfer of Nanofluids
    • Janusz Cieśliński
    • Dawid Lubocki
    • Slawomir Smolen
    2022 Pełny tekst ENERGIES

    Theoretical analysis of the influence of nanoparticles and temperature on the average Nusselt (Nu) number and the average heat transfer coefficient (HTC) during the turbulent flow of nanofluid in a horizontal, round tube was carried out. The Nu number is a function of the Reynolds (Re) number and the Prandtl (Pr) number, which in turn are functions of the thermophysical properties of the liquid and the flow conditions. On the other hand, the thermophysical properties of nanoliquids are primarily a function of nanoparticle concentration (NPC) and temperature. Hence, the correct determination of the value of the Nu number, and then the HTC, which is needed for engineering calculations, depends on the accuracy of determining the thermophysical properties of nanofluids. In most cases, the thermophysical properties of the nanofluids are calculated as functions of the corresponding thermophysical properties of the base liquid. Therefore, the accuracy of the calculations of the thermophysical properties of nanofluids is equally determined by the reliable correlations for the base liquids. Therefore, new correlations for the calculation of the thermophysical properties of water have been developed. The results of calculations of the thermophysical properties of the base liquid (water) and the water-Al2O3 nanofluids by use of carefully selected correlations is presented. It was established that even for small concentrations of nanoparticles, a significant intensification of heat transfer using nanofluids as compared to the base liquid is obtained for the tested temperature range.

  • Impact of the Finite Element Mesh Structure on the Solution Accuracy of a Two-Dimensional Kinematic Wave Equation
    • Dariusz Gąsiorowski
    2022 Pełny tekst Water

    The paper presents the influence of the finite element mesh structure on the accuracy of the numerical solution of a two-dimensional linear kinematic wave equation. This equation was solved using a two-level scheme for time integration and a modified finite element method with triangular elements for space discretization. The accuracy analysis of the applied scheme was performed using a modified equation method for three different uniform triangular meshes with the same resolution, but with a different structure. The modified equation approach based on the Taylor series truncation allowed the numerical diffusivity and dispersivity tensors to be derived, which are directly associated with numerical errors. The derived tensors depend on parameters such as the space and time interval, flow velocity and weighting coefficients. A detailed analysis carried out for the particular values of these parameters enabled an assessment of the numerical errors that may be generated in the solution for the assumed mesh structure. The theoretical analysis was confirmed by using numerical simulations carried out for an arbitrary domain and auxiliary conditions. According to the obtained results, it appeared that it is possible to improve the accuracy of the numerical solution by choosing the proper mesh structure and numerical parameters for the applied algorithm.

  • Impact of thermal loading into the structural performance of ships: A review
    • Krzysztof Wołoszyk
    2022 Pełny tekst OCEAN ENGINEERING

    The presented study reviews the recent advances done regarding the impact of thermal loading on the structural performance of ships. Firstly, the studies related to the mechanical and thermal properties of typical materials used in shipbuilding are outlined. Secondly, a brief introduction to the heat transfer analysis, Finite Element modelling and thermal stresses is provided. Finally, the review of papers dealing with the structural response of ship hull girder elements subjected to thermal loading is outlined. Two main groups of analyses are highlighted, i.e. structural performance at very low and very high temperatures. In each group, the possible future research needs are identified, and conclusions are drawn.

  • Impedance Spectra of RC Model as a Result of Testing Pulse Excitation Measurement Method Dataset
    • Grzegorz Lentka
    2022 Pełny tekst

    The dataset titled Impedance spectra of RC model as a result of testing pulse excitation measurement method contains the impedance spectrum of an exemplary test RC model obtained using pulse excitation. The dataset allows presentation of the accuracy of the impedance spectroscopy measuring instrument, which uses the pulse excitation method to shorten the time of the whole spectrum acquisition.

  • Impedimetric sensing of α-amino acids driven by micro-patterned 1,8-Diazafluoren-9-one into titania- boron- doped maze-like nanocarbons
    • Mattia Pierpaoli
    • Aneta Lewkowicz
    • Bartłomiej Dec
    • Małgorzata Nadolska-Dawidowska
    • Robert Bogdanowicz
    2022 Pełny tekst SENSORS AND ACTUATORS B-CHEMICAL

    The development of impedimetric, non-faradaic label-free sensors for the detection of α-amino acids constitutes a trailblazing technology for the fast and inexpensive quantification of such biomarkers. Since α-amino acids, such as glycine and sarcosine, are basic constituents in biological processes, a variation in their concentration may be an indicator of cardiovascular diseases and metabolic disorders or neurological conditions. The unique properties, including maze-like porosity along with excellent electron transfer behavior, make boron-doped carbon nanowalls (BCNW) an ideal transducer for electrochemical sensing. In order to realize a non-faradaic impedimetric sensor for the detection of α-amino acids, 1,8-diazafluoren-9-one (DFO), a fluorophore commonly used in forensic science, was dispersed into Ti-sol precursor and deposited over a BCNW substrate by spin-coating. Data mining tools have been applied to the raw impedimetric data to directly predict the glycine concentration and to support the underlying material-interface interaction. The developed sensor revealed high selectivity and reproducibility toward glycine and other α-amino acids (phenylamine, sarcosine and tryptophan) and no selectivity toward β-alanine, γ-aminobutyric acid or taurine. The application of density-functional theory (DFT) studies supported the higher affinity with the highest adsorption energy for the reaction product of DFO with glycine. A detection limit of 51 nM was found for glycine.

  • IMPLEMENTACJA ARCHITEKTURY SYSTEMU SYMEC
    • Andrzej Bęben
    • Wojciech Burakowski
    • Maciej Sosnowski
    • Dariusz Więcek
    • Paweł Olender
    • Bartosz Belter
    • Bartosz Krakowiak
    • Michał Hoeft
    • Mariusz Miszewski
    • Adrian Chomicki
    2022 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    W artykule przedstawiono docelową architekturę systemu obliczeń na brzegu sieci, która została opracowana, zaimplementowana i wdrożona w ramach projektu SyMEC. W szczególności przedstawiono główne elementy opracowanego systemu, podstawowe realizowane procesy dotyczące zarządzania cyklem życia oferowanych aplikacji i usług MEC, a także doświadczenia wynikające z implementacji prototypu systemu SyMEC i jego wdrożenia w krajowej sieci badawczej PL-LAB 2020. W podsumowaniu przedstawiono kierunki dalszego rozwoju system SyMEC.

  • Implementation of high-precision computation capabilities into the open-source dynamic simulation framework YADE
    • Jan Kozicki
    • Anton Gladky
    • Klaus Thoeni
    2022 Pełny tekst COMPUTER PHYSICS COMMUNICATIONS

    This paper deals with the implementation of arbitrary precision calculations into the open-source discrete element framework YADE published under the GPL-2+ free software license. This new capability paves the way for the simulation framework to be used in many new fields such as quantum mechanics. The implementation details and associated gains in the accuracy of the results are discussed. Besides the "standard" double (64 bits) type, support for the following high-precision types is added: long double (80 bits), float128 (128 bits), mpfr_float_backend (arbitrary precision) and cpp_bin_float (arbitrary precision). Benchmarks are performed to quantify the additional computational cost involved with the new supported precisions. Finally, a simple calculation of a chaotic triple pendulum is performed to demonstrate the new capabilities and the effect of different precisions on the simulation result.

  • Implementing artificial intelligence in forecasting the risk of personal bankruptcies in Poland and Taiwan
    • Tomasz Korol
    • Anestis Fotiadis
    2022 Pełny tekst Oeconomia Copernicana

    Research background: The global financial crisis from 2007 to 2012, the COVID-19 pandemic, and the current war in Ukraine have dramatically increased the risk of consumer bankruptcies worldwide. All three crises negatively impact the financial situation of households due to increased interest rates, inflation rates, volatile exchange rates, and other significant macroeconomic factors. Financial difficulties may arise when the private person is unable to maintain a habitual standard of living. This means that anyone can become financially vulnerable regardless of wealth or education level. Therefore, forecasting consumer bankruptcy risk has received increasing scientific and public attention. Purpose of the article: This study proposes artificial intelligence solutions to address the increased importance of the personal bankruptcy phenomenon and the growing need for reliable forecasting models. The objective of this paper is to develop six models for forecasting personal bankruptcies in Poland and Taiwan with the use of three soft-computing techniques. Methods: Six models were developed to forecast the risk of insolvency: three for Polish households and three for Taiwanese consumers, using fuzzy sets, genetic algorithms, and artificial neural networks. This research relied on four samples. Two were learning samples (one for each country), and two were testing samples, also one for each country separately. Both testing samples contain 500 bankrupt and 500 nonbankrupt households, while each learning sample consists of 100 insolvent and 100 solvent natural persons. Findings & value added: This study presents a solution for effective bankruptcy risk forecasting by implementing both highly effective and usable methods and proposes a new type of ratios that combine the evaluated consumers’ financial and demographic characteristics. The usage of such ratios also improves the versatility of the presented models, as they are not denominated in monetary value or strictly in demographic units. This would be limited to use in only one country but can be widely used in other regions of the world.

  • Improved finite element method for flow, heat and solute transport of Prandtl liquid via heated plate
    • Muhammad Bilal Hafeez
    • Marek Krawczuk
    • Wasim Jamshed
    • Hajra Kaneez
    • Syed M. Hussain
    • El Sayed M. Tag El Din
    2022 Pełny tekst Scientific Reports

    In the current study, a vertical, 3D-heated plate is used to replicate the generation of heat energy and concentration into Prandtl liquid. We discuss how Dufour and Soret theories relate to the equations for concentration and energy. In order to see how efectively particles, interact with heat and a solvent, hybrid nanoparticles are used. It does away with the phenomena of viscous dissipation and changing magnetic felds. The motivation behind the developed study is to optimize solvent and heat storage uses in the biological and industrial domains. This article’s major goal is to explore the aspects of thermal energy and mass transfer that infuence how nanoparticles, hybrid nanoparticles, and 3D melting surface sheets behave. Variable thermal efciency and variable mass transfer are combined. The system of generated PDEs (diference equations) includes the concentration, velocity, and heat energy equations. The numerical calculations are done for Silver (Ag), Molybdenum Disulfde (MoS2) nanoparticles with Ethylene glycol (C2H6O2) as the base fuid using a boundary layer approach to the mathematical formulation. The system of ODEs is formulated through transformations in order to fnd a solution. A Galerkin fnite element algorithm (G-FEA) is adopted to analyze various aspects versus diferent parameters. It has been found that motion into hybrid nanoparticles is reduced by motion into nanoparticles. Additionally, diferences in heat energy and solvent particle sizes are associated with modifcations in magnetic, Dufour, Eckert, and Soret numbers. In contrast to hybrid nanostructures, the output of thermal energy is usually observed to be substantially higher. The magnetic feld parameter decreases the particle velocity. In contradiction to the Eckert number, bouncy parameter, and magnetic parameter set values, the maximum quantity of heat energy is obtained. variable thermal conductivity’s function. The 3D heated vertical surface convective heat transfer of nanofuids and hybrid nanofuids under the impact of a heat source, thermal radiation, and viscous dissipation has not yet been studied, as far as the authors are aware.

  • Improved-Efficacy EM-Based Antenna Miniaturization by Multi-Fidelity Simulations and Objective Function Adaptation
    • Marzieh Mahrokh
    • Mateusz Kozieł
    2022 Pełny tekst ENERGIES

    The growing demands for integration of surface mount design (SMD) antennas into miniatur-ized electronic devices have been continuously imposing limitations on the structure dimen-sions. Examples include embedded antennas in applications such as on-board devices, picosatel-lites, 5G communications, or implantable and wearable devices. The demands for size reduction while ensuring a satisfactory level of the electrical and field performance figures can be man-aged through constrained numerical optimization. The reliability of optimization-based size reduction requires utilization of full-wave electromagnetic (EM) analysis, which entails signifi-cant computational costs. This can be alleviated by incorporating surrogate modeling tech-niques, adjoint sensitivities, or the employment of sparse sensitivity updates. An alternative is the incorporation of multi-fidelity simulation models, normally limited to two levels, low and high resolution. This paper proposes a novel algorithm for the accelerated antenna miniaturiza-tion, featuring a continuous adjustment of the simulation model fidelity in the course of the op-timization process. The model resolution is determined by factors related to violation of the de-sign constraints as well as and the convergence status of the algorithm. The algorithm utilizes the lowest-fidelity model for the early stages of the optimization process; it is gradually refined towards the highest-fidelity model upon approaching convergence, and the constraint violations improve towards the preset tolerance threshold. At the same time, a penalty function approach with adaptively adjusted coefficients is applied to enable a precise control of constraints, and to increase the achievable miniaturization rates. The presented procedure has been validated using five microstrip antennas, including three broadband, and two circularly polarized structures. The obtained results corroborate the relevance of the implemented mechanisms from the point of view of improving the average computational efficiency of the optimization pro-cess by 43% as compared to the single-fidelity adaptive penalty function approach. Fur-thermore, the presented methodology demonstrates a performance quality equivalent or even superior to the single-fidelity counterpart in terms of the average constraint violation of 0.01 dB (compared to 0.03 dB for the reference), and the average size reduction of 25% as compared to 25.6%.

  • Improvement of CO2 absorption and inhibition of NH3 escape during CaCO3 precipitation in the presence of selected alcohols and polyols
    • Natalia Czaplicka
    • Dominik Dobrzyniewski
    • Szymon Dudziak
    • Chunqing Jiang
    • Donata Konopacka-Łyskawa
    2022 Pełny tekst Journal of CO2 Utilization

    This research aims to investigate the effect of selected organic substances containing hydroxyl groups on the reduction of NH3 escape and the improvement of CO2 capture during the precipitation of calcium carbonate by carbonation method using post-distillation liquid from the Solvay process and gas stream containing CO2 in the amount corresponding to the exhausted gases produced by the combustion of fossil fuels. Glycerol, ethylene glycol (EG), methanol, isopropanol, pentaerythritol, and neopentyl glycol (NPG) were used as ammonia escape inhibitors. The addition of NPG has been shown to result in the highest reduction of NH3 escape (83.1%) and the highest CO2 capture efficiency (86.1%). During the proposed CaCO3 precipitation with NPG, 98.7% of the NH3 initially introduced into the reaction mixture remains in the solution. Furthermore, the features that should be taken into account when introducing various alcohols and polyols for capturing NH3 and CO2 in the calcium carbonate precipitation via the carbonation method have been discussed.

  • Improvements and new functionalities of UNRES server for coarse-grained modeling of protein structure, dynamics, and interactions
    • Rafał Ślusarz
    • Emilia Lubecka
    • Cezary Czaplewski
    • Adam Liwo
    2022 Pełny tekst Frontiers in Molecular Biosciences

    In this paper we report the improvements and extensions of the UNRES server (https://unres-server.chem.ug.edu.pl) for physics-based simulations with the coarse-grained UNRES model of polypeptide chains. The improvements include the replacement of the old code with the recently optimized one and adding the recent scale-consistent variant of the UNRES force field, which performs better in the modeling of proteins with the β and the α+β structures. The scope of applications of the package was extended to data-assisted simulations with restraints from nuclear magnetic resonance (NMR) and chemical crosslink mass-spectroscopy (XL-MS) measurements. NMR restraints can be input in the NMR Exchange Format (NEF), which has become a standard. Ambiguous NMR restraints are handled without expert intervention owing to a specially designed penalty function. The server can be used to run smaller jobs directly or to prepare input data to run larger production jobs by using standalone installations of UNRES.

  • Improving medical experts’ efficiency of misinformation detection: an exploratory study
    • Aleksandra Nabożny
    • Bartłomiej Balcerzak
    • Mikołaj Morzy
    • Adam Wierzbicki
    • Pavel Savov
    • Kamil Warpechowski
    2022 Pełny tekst WORLD WIDE WEB-INTERNET AND WEB INFORMATION SYSTEMS

    Fighting medical disinformation in the era of the pandemic is an increasingly important problem. Today, automatic systems for assessing the credibility of medical information do not offer sufficient precision, so human supervision and the involvement of medical expert annotators are required. Our work aims to optimize the utilization of medical experts’ time. We also equip them with tools for semi-automatic initial verification of the credibility of the annotated content. We introduce a general framework for filtering medical statements that do not require manual evaluation by medical experts, thus focusing annotation efforts on non-credible medical statements. Our framework is based on the construction of filtering classifiers adapted to narrow thematic categories. This allows medical experts to fact-check and identify over two times more non-credible medical statements in a given time interval without applying any changes to the annotation flow. We verify our results across a broad spectrum of medical topic areas. We perform quantitative, as well as exploratory analysis on our output data. We also point out how those filtering classifiers can be modified to provide experts with different types of feedback without any loss of performance.

  • Improving Re-rankCCP with Rules Quality Measures
    • Piotr Jezusek
    • Aleksandra Karpus
    2022

    Recommender Systems are software tools and techniques which aim at suggesting new items that may possibly be of interest to a user. Context-Aware Recommender Systems exploit contextual information to provide more adequate recommendations. In this paper we described a modification of an existing contextual post-filtering algorithm which uses rules-like user representation called Contextual Conditional Preferences. We extended the algorithm by taking into account rules quality measures while recommending items to a user. We proved that this modification increases the quality of recommendations, measured with precision, recall and nDCG, and has no impact on the execution time of the original algorithm.

  • In vivo imaging of the human eye using a two-photon excited fluorescence scanning laser ophthalmoscope
    • Jakub Boguslawski
    • Grazyna Palczewska
    • Slawomir Tomczewski
    • Jadwiga Milkiewicz
    • Piotr Kasprzycki
    • Dorota Stachowiak
    • Katarzyna Komar
    • Marcin Jarosław Marzejon
    • Bartosz L. Sikorski
    • Arkadiusz Hudzikowski
    • Aleksander Głuszek
    • Zbigniew Łaszczych
    • Karol Karnowski
    • Grzegorz Soboń
    • Krzysztof Palczewski
    • Maciej Wojtkowski
    2022 Pełny tekst JOURNAL OF CLINICAL INVESTIGATION

    BACKGROUND. Noninvasive assessment of metabolic processes that sustain regeneration of human retinal visual pigments (visual cycle) is essential to improve ophthalmic diagnostics and to accelerate development of new treatments to counter retinal diseases. Fluorescent vitamin A derivatives, which are the chemical intermediates of these processes, are highly sensitive to UV light; thus, safe analyses of these processes in humans are currently beyond the reach of even the most modern ocular imaging modalities. METHODS. We present a compact fluorescence scanning laser ophthalmoscope (TPEF-SLO) and spectrally resolved images of the human retina based on two-photon excitation (TPE) with near-infrared (IR) light. A custom Er:fiber laser with integrated pulse selection, along with intelligent post-processing of data, enables excitation with low laser power and precise measurement of weak signals. RESULTS. We demonstrate spectrally resolved TPE fundus images of human subjects. Comparison of TPE data between human and mouse models of retinal diseases revealed similarity with mouse models that rapidly accumulate bisretinoid condensation products. Thus, visual cycle intermediates and toxic byproducts of this metabolic pathway can be measured and quantified by TPE imaging. CONCLUSION. Our work establishes a TPE instrument and measurement method for noninvasive metabolic assessment of the human retina. This approach opens the possibility for monitoring eye diseases in the earliest stages before structural damage to the retina occurs. FUNDING. NIH, Research to Prevent Blindness, Foundation for Polish Science, European Regional Development Fund, Polish National Agency for Academic Exchange and Polish Ministry of Science and Higher Education.

  • Incorporation of the sulfur cycle in sustainable nitrogen removal systems - A review
    • Dominika Grubba
    • Zhixuan Yin
    • Joanna Majtacz
    • Hussein Al- Hazmi
    • Jacek Mąkinia
    2022 Pełny tekst JOURNAL OF CLEANER PRODUCTION

    In wastewater treatment systems, sulfur (S) removal processes are generally based on heterotrophic sulfate (SO42−) reduction by sulfate reducing bacteria and S-dependent autotrophic denitrification by sulfur oxidizing bacteria. A combination of either two cycles (N and S) or three cycles (N, S and C) appears to be a viable approach to sustainable wastewater treatment, resulting in energy savings and reduction of sludge production. This review shows how the S cycle can be coupled with the other cycles in single systems for efficient N and S removal. Operating conditions, advantages, limitations and challenges of such systems are described. S removal processes are generally based on heterotrophic sulfate (SO42−) reduction by sulfate reducing bacteria and S-dependent autotrophic denitrification by sulfur oxidizing bacteria. In terms of pH and temperature, the optimum conditions are determined by the narrowest ranges for heterotrophic SO42− reduction (pH of 7–7.6, T = 28–30 °C). The combined processes allow for almost complete N removal, while the efficiency of SO42− removal can reach up to 75%. Among all the processes linking the N, S and C cycles, SANI (sulfate reduction, autotrophic denitrification and nitrification integrated) has been best recognized. Recently, the growing attention has been paid to the novel sulfammox process, which involves SO42− dependent, anaerobic ammonia oxidizing bacteria. Numerous systems have been developed to combine SO42− reduction, S-dependent autotrophic denitrification and partial nitritation/anammox processes. The coexistence of several bacterial groups and their competition for the substrates is thus a key issue to be considered. Specific inhibitors for each bacterial group also need to be recognized before full-scale implementations. Moreover, modeling the transformations of S compounds has been incorporated with respect to all the processes responsible for those transformations.

  • Incremental dynamic analysis and fragility assessment of buildings founded on different soil types experiencing structural pounding during earthquakes
    • Mahmoud Miari
    • Robert Jankowski
    2022 ENGINEERING STRUCTURES

    The effect of the soil type on buildings experiencing pounding during earthquakes is investigated in this study using the incremental dynamic analysis and fragility assessment methods. Three 3-D structures with different number of storeys (4, 6 and 8) were considered in this study. Three pounding scenarios between these three buildings were taken into account, i.e. pounding between 4-storey and 6-storey buildings, between 4-storey and 8-storey buildings and between 6-storey and 8-storey buildings. First, the effect of the site parameters was investigated so as to take into consideration the values that lead to higher responses. Then, the effects of earthquake-induced pounding between buildings founded on a specified soil type for these three pounding scenarios were analysed and compared with no pounding case. Finally, pounding for these three scenarios was studied under different soil types defined in the ASCE 7-10 code (hard rock, rock, very dense soil and soft rock, stiff soil and soft clay soil). The results of this study indicate that the effect of pounding follows two general trends which are destructive and beneficial. Also, the vibrating buildings was found to be more vulnerable to damage due to pounding when they are founded on the soft clay soil, then when they are founded on the stiff soil, then when they are founded on very dense soil and soft rock, and finally when they are founded on the rock and hard rock.

  • Incremental Dynamic Analysis and Fragility Assessment of Buildings with Different Structural Arrangements Experiencing Earthquake-Induced Structural Pounding
    • Mahmoud Miari
    • Robert Jankowski
    2022

    Structural pounding is considered as one of the most critical phenomena occurring during earthquakes. This paper presents the incremental dynamic analysis and fragility assessment of buildings experiencing earthquake-induced pounding. Three 3-D buildings with different number of storeys and under different structural arrangements have been considered. Three pounding scenarios have been taken into account, i.e. pounding between 5-storey and 7-storey buildings, pounding between 5-storey and 9-storey buildings and pounding between 7-storey and 9-storey buildings. The incremental dynamic analysis and fragility assessment has been performed for these three buildings in the three pounding scenarios as well as for the no pounding case. The results of both incremental dynamic analysis and fragility assessment illustrate that pounding can be beneficial and destructive, depending on the structural response and ground motion shift versus time. No clear relation has been observed because pounding is a highly complicated phenomenon.

  • INDFIRES PROJECT AND SITUATIONAL INDUSTRIAL FIRE REPORTS OF PARTNER COUNTRIES
    • Yilmaz Olcay
    • Kim Lintrup
    • Mariusz Jaczewski
    • Marek Pszczoła
    • Maciej Sawicki
    • Mateja Gris
    • Marcel Kalan
    • Kasim Yilmaz
    2022

    Chapter contains information regarding project and situational reports from all participants.

  • Individual entrepreneurial orientation: comparison of business and STEM students
    • Magdalena Licznerska
    • Tatjana Nikitina
    • Iveta Ozoliņa-Ozola
    • Inga Lapina
    2022 Education and Training

    Abstract Purpose – The purpose of this study is to determine whether there are differences in Individual Entrepreneurial Orientation (IEO) between students who are doing their major in business studies and the ones whose areas of study are science, technology, engineering, and mathematics (STEM). Design/methodology/approach – The current research investigates which factors and components contribute to EO orientation development among different groups of students. The researchers conducted a survey in Latvia and Poland applying non-parametric inferential statistical methods as well as linear regression analysis to verify the research hypotheses. Findings – The authors identified that there are significant differences between business and STEM students when they analyse their IEO. It turned out that STEM students obtain significantly lower scores for risk-taking and innovativeness but higher for proactiveness. Additionally, it was detected that the chosen field of study affects students’ perception of educational support, thus influencing their innovativeness, proactiveness, and risk propensity. Originality/value – The current research investigates which factors and components contribute to IEO development among different groups of students in under-researched Baltic countries which experienced systemic transformation. The authors believe that universities can use the analysis of their students’ IEO to better allocate their resources, adjust curricula to the real needs of students, because undeniably future societies need entrepreneurial people.

  • Induction Generator with Direct Control and a Limited Number of Measurements on the Side of the Converter Connected to the Power Grid
    • Andrzej Kasprowicz
    • Oleksandr Husev
    • Ryszard Strzelecki
    2022 Pełny tekst ENERGIES

    The article presents an induction generator connected to the power grid using the AC/DC/AC converter and LCL coupling filter. Three-level inverters were used in the converter, both from the generator side and the power grid side. The algorithm realizing Pulse Width Modulation (PWM) in inverters has been simplified to the maximum. Control of the induction generator was based on the Direct Field-Oriented Control (DFOC) method. At the same time, voltage control has been used for this solution. TheMPPT algorithm has been extended to include the variable pitch range of wind turbine blades. The active voltage balancing circuit has been used in the inverter DC voltage circuit. In the control system of the grid converter with an LCL filter, the number of measurements was limited to the measurement of power grid currents and voltages. Synchronization of control from the power grid side is ensured by the use of a PLL loop with the system of preliminary suppression of undesired harmonics.

  • INDUSTRIAL FIRE SAFETY REQUIREMENTS IN PARTNER COUNTRIES
    • Bora Balun
    • Yilmaz Olcay
    • Salvatore Santuccio
    • Mariusz Jaczewski
    2022

    Chapter contains information regardin law regulations of fire safety for constructions in countris participating in project.

  • Infinite chromatic games
    • Robert Janczewski
    • Paweł Obszarski
    • Krzysztof Turowski
    • Bartłomiej Wróblewski
    2022 Pełny tekst DISCRETE APPLIED MATHEMATICS

    In the paper we introduce a new variant of the graph coloring game and a new graph parameter being the result of the new game. We study their properties and get some lower and upper bounds, exact values for complete multipartite graphs and optimal, often polynomial-time strategies for both players provided that the game is played on a graph with an odd number of vertices. At the end we show that both games, the new and the classic one, are related: our new parameter is an upper bound for the game chromatic number.

  • Influence of a Lighting Column in the Working Width of a W-Beam Barrier on TB51 Crash Test
    • Radosław Wolny
    • Dawid Bruski
    • Marcin Budzyński
    • Łukasz Pachocki
    • Krzysztof Wilde
    2022 Pełny tekst Materials

    Road equipment, such as, e.g., road safety barriers and lighting columns, are subject to certification according to the EN1317 standard to be allowed for use on European roads. In engineering practice, due to the terrain conditions, there are cases where other road equipment is installed within the working width of road safety barriers. Such situations are not considered during the certification process. Hence, the aim of this study is to analyze the effect of a lighting column installed within the working width of the barrier on the results of the TB51 crash test. The full-scale crash test and numerical simulation of this event were conducted. In the full-scale crash test, as well as in the simulation, the lighting column prevented the barrier’s post from properly disconnecting from the guardrail, which resulted in the barrier failing to restrain and redirect the 13-t bus. The simulation was quantitatively compared to the experiment, where the correlation coefficient of ASI curves equaled 84%. The THIV curves differed significantly between the experiment and the simulation, which is explained within the paper. Next, simulations with and without the lighting column were compared. The ASI and THIV in the simulation without the column were 0.33 and 16.1 km/h, respectively. In the simulation with the column, the ASI and THIV were 0.44 and 17.7 km/h, respectively. The maximum roll angle of the vehicle in the simulation without the column was 2.01° and with the column was 5.96°. The main difference, however, was that the system without the lighting column within the working width of the barrier was capable of properly restraining and redirecting the vehicle. The specific mechanics underlying this behavior are described within the paper.

  • Influence of B/N co-doping on electrical and photoluminescence properties of CVD grown homoepitaxial diamond films
    • Srinivasu Kunuku
    • Mateusz Ficek
    • Aleksandra Wieloszynska
    • Magdalena Daniela Tamulewicz-Szwajkowska
    • Krzysztof Gajewski
    • Miroslaw Sawczak
    • Aneta Lewkowicz
    • Jacek Ryl
    • Teodor Gotszalk
    • Robert Bogdanowicz
    2022 Pełny tekst NANOTECHNOLOGY

    Boron doped diamond (BDD) has great potential in electrical, and electrochemical sensing applications. The growth parameters, substrates, and synthesis method play a vital role in the preparation of semiconducting BDD to metallic BDD. Doping of other elements along with boron (B) into diamond demonstrated improved efficacy of B doping and exceptional properties. In the present study, B and nitrogen (N) co-doped diamond has been synthesized on single crystalline diamond (SCD) IIa and SCD Ib substrates in a microwave plasma-assisted chemical vapor deposition process. The B/N co-doping into CVD diamond has been conducted at constant N flow of N/C ~ 0.02 with three different B/C doping concentrations of B/C ~ 2500 ppm, 5000 ppm, 7500 ppm. AFM topography depicted the flat and smooth surface with low surface roughness for low B doping, whereas surface features like hillock structures and un-epitaxial diamond crystals with high surface roughness were observed for high B doping concentrations. KPFM measurements revealed that the work function (4.74 eV to 4.94 eV) has not varied significantly for CVD diamond synthesized with different B/C concentrations. Raman spectroscopy measurements described the growth of high-quality diamond and photoluminescence studies revealed the formation of high-density nitrogen-vacancy centers in CVD diamond layers. X-ray photoelectron spectroscopy results confirmed the successful B doping and the increase in N doping with B doping concentration. The room temperature electrical resistance measurements of CVD diamond layers (B/C ~ 7500 ppm) have shown the low resistance value ~ 9.29 Ω for CVD diamond/SCD IIa, and the resistance value ~ 16.55 Ω for CVD diamond/SCD Ib samples.

  • Influence of Cement Replacement with Sewage Sludge Ash (SSA) on the Heat of Hydration of Cement Mortar
    • Elżbieta Haustein
    • Aleksandra Kuryłowicz-Cudowska
    • Aneta Łuczkiewicz
    • Sylwia Fudala-Książek
    • Bartłomiej Cieślik
    2022 Pełny tekst Materials

    The amount of fly ash from the incineration of sewage sludge is increasing all over the world, and its utilization is becoming a serious environmental problem. In the study, a type of sewage sludge ash (SSA) collected directly from the municipal sewage treatment plant was used. Five levels of cement replacement (2.5%, 5%, 7.5%, 10% and 20%) and unchanged water-to-binder (w/b) ratio (0.55) were used. The purpose of the study was to evaluate the effect of sewage sludge ash (SSA) on the hydration heat process of cement mortars. The heat of the hydration of cement mortars was monitored by the isothermal calorimetric method for 7 days at 23 °C. The analysis of chemical composition and particle size distribution was performed on the tested material. The tests carried out have shown that SSA particles have irregular grain morphology and, taking into account the chemical composition consists mainly of oxides such as CaO, P2O5, SiO2 and Al2O3. The concentration of these compounds affects the hydration process of cement mortars doped with SSA. In turn, the content of selected heavy metals in the tested ash should not pose a threat to the environment. Calorimetric studies proved that the hydration process is influenced by the presence of SSA in cement mortars. The studies showed that the rate of heat generation decreased (especially in the initial setting period) with the increasing replacement of cement by SSA, which also reduced the amount of total heat compared to the control cement mortar. With increasing mass of the replacement of cement with SSA up to 20%, the 7-day compressive strength of the mortar samples decreases.

  • Influence of Different Nanometals Implemented in PMMA Bone Cement on Biological and Mechanical Properties
    • Beata Świeczko-Żurek
    • Andrzej Zieliński
    • Dorota Bociąga
    • Karolina Rosińska
    • Grzegorz Gajowiec
    2022 Pełny tekst Nanomaterials

    Cemented arthroplasty is a common process to fix prostheses when a patient becomes older and his/her bone quality deteriorates. The applied cements are biocompatible, can transfer loads, and dampen vibrations, but do not provide antibacterial protection. The present work is aimed at the development of cement with antibacterial effectivity achieved with the implementation of nanoparticles of different metals. The powders of Ag, Cu with particles size in a range of 10–30 nm (Cu10) and 70–100 nm (Cu70), AgCu, and Ni were added to PMMA cement. Their influence on compression strength, wettability, and antibacterial properties of cement was assessed. The surface topography of samples was examined with biological and scanning electron microscopy. The mechanical properties were determined by compression tests. A contact angle was observed with a goniometer. The biological tests included an assessment of cytotoxicity (XTT test on human cells Saos-2 line) and bacteria viability exposure (6 months). The cements with Ag and Cu nanopowders were free of bacteria. For AgCu and Ni nanoparticles, the bacterial solution became denser over time and, after 6 months, the bacteria clustered into conglomerates, creating a biofilm. All metal powders in their native form in direct contact reduce the number of eukaryotic cells. Cell viability is the least limited by Ag and Cu particles of smaller size. All samples demonstrated hydrophobic nature in the wettability test. The mechanical strength was not significantly affected by the additions of metal powders. The nanometal particles incorporated in PMMA-based bone cement can introduce long-term resistance against bacteria, not resulting in any serious deterioration of compression strength.

  • Influence of Fluid Compressibility and Movements of the Swash Plate Axis of Rotation on the Volumetric Efficiency of Axial Piston Pumps
    • Paweł Załuski
    2022 Pełny tekst ENERGIES

    This paper describes the design of a swash plate axial piston pump and the theoretical models describing the bulk modulus of aerated and non-aerated fluids. The dead space volume is defined and the influence of this volume and the fluid compressibility on the volumetric efficiency of the pump is considered. A displacement of the swash plate rotation axis is proposed to reduce the dead space volume for small swash plate swing angles. A prototype design of a pump with a displaced axis of rotation of a swash plate with two directions of delivery is presented, in which the capacity is changed by means of a valve follow-up mechanism. Comparative results for a pump with a displaced and a non-displaced swash plate rotation axis are presented, which confirm that displacement of the swash plate rotation axis causes an increase in volumetric efficiency that is apparent for high pressure discharge and small swash plate angles. The determined characteristics were compared with a mathematical model taking into account the compressibility of the fluid in the dead space volume and a satisfactory consistency was obtained.

  • Influence of Heat Treatment Temperature on Fatigue Toughness in Medium-Carbon High-Strength Steels
    • G. Wheatley
    • Ricardo Branco
    • José A. F. O. Correia
    • Rui F. Martins
    • Wojciech Macek
    • Zbigniew Marciniak
    • M. Szala
    2022 Pełny tekst Structural Integrity

    Current research has demonstrated that the tempering temperature affects the martensitic transformation of medium-carbon high-strength steels. This temperature plays an important role in the final microstructure, percentage ratios of martensite to ferrite phases and, consequently, in the mechanical properties and the fatigue response. So far, the relationship between the martensitic tempering temperature and the cyclic deformation properties is not clearly understood. Moreover, the effect of the martensitic tempering temperature on fatigue toughness has not been studied yet. Therefore, this paper aims to study, in a systematic manner, the fatigue toughness of medium-carbon high-strength steels heat treated at different temperatures under fully reversed strain-controlled conditions.

  • Influence of Laser Modification on the Surface Character of Biomaterials: Titanium and Its Alloys—A Review
    • Joanna Sypniewska
    • Marek Szkodo
    2022 Pełny tekst Coatings

    Laser surface modification is a widely available and simple technique that can be applied to different types of materials. It has been shown that by using a laser heat source, reproducible surfaces can be obtained, which is particularly important when developing materials for medical applications. The laser modification of titanium and its alloys is advantageous due to the possibility of controlling selected parameters and properties of the material, which offers the prospect of obtaining a material with the characteristics required for biomedical applications. This paper analyzes the effect of laser modification without material growth on titanium and its alloys. It addresses issues related to the surface roughness parameters, wettability, and corrosion resistance, and discusses how laser modification changes the hardness and wear resistance of materials. A thorough review of the literature on the subject provides a basis for the scientific community to develop further experiments based on the already investigated relationships between the effects of the laser beam and the surface at the macro, micro, and nano level.

  • Influence of Material Thickness on the Ductile Fracture of Steel Plates for Shipbuilding
    • Jakub Kowalski
    • Janusz Kozak
    2022 Pełny tekst Polish Maritime Research

    In the shipbuilding industry, the risk of brittle fractures is relatively high because some units operate in arctic or subarcticzones and use high thickness (up to 100 mm) steel plates in their structures. This risk is limited by employing certifiedmaterials with a specific impact strength, determined using the Charpy method (for a given design temperature) and byexercising control over the welding processes (technology qualification, production supervision, and non-destructive tests).However, for offshore constructions, such requirements may prove insufficient. For this reason, regulations employed inconstructing offshore structures require conducting crack tip opening displacement (CTOD) tests for steel and weldedjoints with thicknesses exceeding 40 mm for high tensile strength steel and 50 mm for other steel types. Since classificationcodes do not accept the results of CTOD tests conducted on specimens of sub-sized dimensions, the problem of theoreticallymodelling the steel construction destruction process is of key importance, as laboratory tests for notched elements ofconsiderable thickness (100 mm and higher) are costly and problems stemming from high loads and a wide range ofrecorded parameters are not uncommon. The aim of this research is to find a relationship between material thickness andCTOD value, by establishing and verifying a numerical model that allows recalculating a result obtained on a sub-sizespecimen to a full- size specimen for a ductile fracture mode. This work presents results and conclusions from numericalmodelling and compares them with laboratory test results of the elastic-plastic properties of high thickness steel, typicallyused in offshore applications.

  • Influence of PWHT Parameters on the Mechanical Properties and Microstructural Behavior of Multi-Pass GTAW Joints of P92 Steel
    • Sachin Sirohi
    • Amit Kumar
    • Shiva Soni
    • Gaurav Dak
    • Sanjeev Kumar
    • Aleksandra Świerczyńska
    • Grzegorz Rogalski
    • Dariusz Fydrych
    • Chandan Pandey
    2022 Pełny tekst Materials

    The 9% Cr steels were developed for ultra-supercritical (USC) power plants to meet the requirements of high operating temperature and pressure. These steels are produced to operate at high temperatures where impact toughness is not a concern; however, it becomes important for the welded joints to have good impact toughness at room temperature for manufacturing. The present work investigates the effect of the post-weld heat treatment (PWHT) parameters, i.e., temperature and time, on the impact toughness of multi-pass gas tungsten arc welded (GTAW) joints of ferritic/martensitic grade P92 steel. The microstructural evolution in welded joints given varying post-weld temperatures and times was studied. The lath martensitic structure of the weld metal for the as-welded joints resulted in high hardness and low impact toughness. The weld fusion zone toughness was 12 J, which was lower than the minimum specified values of 41 J (ASME standards) and 47 J (EN ISO 3580:2017). The PWHT temperature and time were found to have a significant effect on the impact toughness of the weld metal. A drastic increase in the impact toughness of the weld metal was noticed, which was attributed to lath break-up, reduction in dislocation density and reduction in solid solution hardening. The maximum impact toughness of 124 J was measured for PWHT temperature and time of 760 C and 120 min, respectively. The effect of PWHT parameters on tensile strength was also investigated, and test results showed that the joint was safe for USC boiler application as it failed from the region of the P92 base metal. The variation in microstructural evolution along the weldments resulted in hardness variation. PWHT led to homogeneity in microstructure and, ultimately, reduction in hardness value. According to the study, the optimum temperature and time for PWHT of a GTAW joint of P92 steel were found to be 760 C and 120 min, respectively.

  • Influence of Rock Dust Additives as Fine Aggregate Replacement on Properties of Cement Composites—A Review
    • Magdalena Dobiszewska
    • Orlando Bagcal
    • Ahmet Beycioğlu
    • Dimitrios Goulias
    • Fuat Köksal
    • Maciej Niedostatkiewicz
    • Hüsamettin Ürünveren
    2022 Pełny tekst Materials

    Concrete production consumes enormous amounts of fossil fuels, raw materials, and is energy intensive. Therefore, scientific research is being conducted worldwide regarding the possibility of using by-products in the production of concrete. The objective is not only to identify substitutes for cement clinker, but also to identify materials that can be used as aggregate in mortar and concrete productions. Among the potential alternative materials that can be used in cement composite production is rock dust of different geological origin. However, some adversarial effects may be encountered when using rock dust regarding the properties and durability of mortars and concrete. Therefore, comprehensive research is needed to evaluate the adequacy of rock dust use in cementitious composite production. This paper presents a comprehensive review of the scientific findings from past studies concerning the use of various geological origins of rock dust in the production of mortars and concrete. The influence of rock dust as a replacement of fine aggregates on cementitious composites was analyzed and evaluated. In this assessment and review, fresh concrete and mortar properties, i.e., workability, segregation, and bleeding, mechanical properties, and the durability of hardened concrete and mortar were considered.

  • Influence of stabilizing osmolytes on hen egg white lysozyme fibrillation
    • Jarosław Wawer
    • Emilia Kaczkowska
    • Jakub Karczewski
    • Danuta Augustin-Nowacka
    • Joanna Krakowiak
    2022 JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS

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  • Influence of Surface Modification of Titanium and Its Alloys for Medical Implants on Their Corrosion Behavior
    • Łukasz Pawłowski
    • Magda Rościszewska
    • Beata Majkowska-Marzec
    • Magdalena Jażdżewska
    • Michał Bartmański
    • Andrzej Zieliński
    • Natalia Tybuszewska
    • Pamela Samsel
    • Majkowska-marzec Beata
    2022 Pełny tekst Materials

    Titanium and its alloys are often used for long-term implants after their surface treatment. Such surface modification is usually performed to improve biological properties but seldom to increase corrosion resistance. This paper presents research results performed on such metallic materials modified by a variety of techniques: direct voltage anodic oxidation in the presence of fluorides, micro-arc oxidation (MAO), pulse laser treatment, deposition of chitosan, biodegradable Eudragit 100 and poly(4-vinylpyridine (P4VP), carbon nanotubes, nanoparticles of TiO2, and chitosan with Pt (nano Pt) and polymeric dispersant. The open circuit potential, corrosion current density, and potential values were determined by potentiodynamic technique, and microstructures of the surface layers and coatings were characterized by scanning electron microscopy. The results show that despite the applied modifications, the corrosion current density still appears in the region of very low values of some nA/cm2. However, almost all surface modifications, designed principally for the improvement of biological properties, negatively influence corrosion resistance. The reasons for observed effects can vary, such as imperfections and permeability of some coatings or accelerated degradation of biodegradable deposits in simulated body fluids during electrochemical testing. Despite that, all coatings can be accepted for biological applications, and such corrosion testing results are presumed not to be of major importance for their applications in medicine.

  • Influence of the Shear Cap Size and Stiffness on the Distribution of Shear Forces in Flat Slabs
    • Maciej Grabski
    • Andrzej Ambroziak
    2022 Pełny tekst Materials

    The scope of this paper is to investigate analytically and numerically the influence of shear cap size and stiffness on the distribution of shear forces in flat slabs in a slab–column-connections-reinforced concrete structure. The effect of support (shear cap) stiffness on the calculation of the length of the shear control perimeter according to the available methods is presented. Based on the analysis, the authors indicate in what range of support stiffness the corner concentrations become important in the calculation of the punching resistance. For shear caps with high flexibility (≤ 0.5), the concentration of internal forces in the corners does not occur. The authors compare the numerical results obtained from the calculation methods and indicate the correlations, which can be useful guidance for structural designers. In the case of large shear caps, the simplified MC2010 method gives a significantly lower value of the effective control perimeter length compared to more accurate methods. This paper is intended to provide scientists, civil engineers, and designers with guidelines on which factors influence punching shear load capacity of the slab–column connections with shear caps.

  • Influence of the Tool Rotational Speed on Physical and Chemical Properties of Dissimilar Friction-Stir-Welded AA5083/AA6060 Joints
    • Aleksandra Laska
    • Marek Szkodo
    • Pasquale Cavaliere
    • Angelo Perrone
    2022 Pełny tekst Metals

    Aluminum alloys have been successfully used in the railroad and automotive industries because of their potential to significantly reduce component weights, and their good mechanical and anti-corrosion properties. Problems with joining aluminum alloys are characterized by low weldability, which influences the need for studies focused on unconventional methods. The environmentally friendly and low-cost friction-stir-welding method enables the material to be joined without melting. In the following study, dissimilar butt joints were produced from AA5083 and AA6060 alloys. A constant tool traverse speed of 100 mm/min and a tool tilt angle of 2º were used, combined with tool rotational speeds of 800, 1000 and 1200 RPM. It was revealed that as the tool speed increases, the hardness in the weld nugget zone increases, due to higher heat input and more effective recrystallization. The highest hardness of the mweld nugget zone was observed for the weld that was produced with the highest tool rotational speed, and was equal to 1.07 GPa, compared to the hardness of both parent materials of 0.75 and 1.15 GPa for AA5083 and AA6060, respectively. mIncreasing the heat input also decreased the hardness of the heat-affected zone, where recrystallization was not bobserved. The lowest density of dislocations with the highest mobility was observed in the heat-affected zone on the AA6060 side, which also contributed to the reduction in strength in this zone. The produced welds exhibited corrosion resistance between both parent materials, with the lowest corrosion current density being 6.935 ± 0.199 µA·cm–2 for the weld that was produced at a tool speed of 1200 RPM.

  • Influence of Urea and Dimethyl Sulfoxide on K-Peptide Fibrillation
    • Jarosław Wawer
    • Jakub Karczewski
    • Robert Aranowski
    • Rafał Piątek
    • Danuta Augustin-Nowacka
    • Piotr Bruździak
    2022 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Protein fibrillation leads to formation of amyloids—linear aggregates that are hallmarks of many serious diseases, including Alzheimer’s and Parkinson’s diseases. In this work, we investigate the fibrillation of a short peptide (K-peptide) from the amyloidogenic core of hen egg white lysozyme in the presence of dimethyl sulfoxide or urea. During the studies, a variety of spectroscopic methods were used: fluorescence spectroscopy and the Thioflavin T assay, circular dichroism, Fourier-transform infrared spectroscopy, optical density measurements, dynamic light scattering and intrinsic fluorescence. Additionally, the presence of amyloids was confirmed by atomic force microscopy. The obtained results show that the K-peptide is highly prone to form fibrillar aggregates. The measurements also confirm the weak impact of dimethyl sulfoxide on peptide fibrillation and distinct influence of urea. We believe that the K-peptide has higher amyloidogenic propensity than the whole protein, i.e., hen egg white lysozyme, most likely due to the lack of the first step of amyloidogenesis—partial unfolding of the native structure. Urea influences the second step of K-peptide amyloidogenesis, i.e., folding into amyloids.

  • Influence of User Mobility and Antenna Placement on System Loss in B2B Networks
    • Manuel M. Ferreira
    • Filipe D. Cardoso
    • Sławomir Ambroziak
    • Luis M. Correia
    2022 Pełny tekst IEEE Access

    In this paper, the influence of user mobility and on-body antenna placement on system loss in body-to-body communications in indoor and outdoor environments and different mobility scenarios is studied, based on system loss measurements at 2.45 GHz. The novelty of this work lies on the proposal of a classification model to characterise the effect of user mobility and path visibility on system loss, allowing to identify the best set of on-body antenna placements. To quantify the influence of visibility and mobility on the average system loss, a combined score is proposed, allowing to map system loss onto the degree of visibility and mobility that depends on the scenario being considered and on on-body antenna placements. Overall, a good agreement is observed between the proposed classification model and the average measured values of system loss, with the higher values of combined scores being associated with lower values of systems loss. For the cases under study, the average values of system loss are 61.6 dB for the cases of the antennas being positioned only on the front of the body and/or the head, and 64.5 dB if at least one of the antennas is placed on an arm.

  • Influence of Water-Induced Degradation of Polytetrafluoroethylene (PTFE)-Coated Woven Fabrics Mechanical Properties
    • Andrzej Ambroziak
    • Paweł Kłosowski
    2022 Pełny tekst Materials

    The impact of water-induced degradation on the mechanical properties of the chosen two PTFE-coated, glass threads woven fabrics is investigated in this paper. The paper begins with a survey of literature concerning the investigation and determination of coated woven fabric properties. The authors carried out the uniaxial tensile tests with an application of flat and curved grips to establish the proper values of the ultimate tensile strength and the longitudinal stiffness of groups of specimens treated with different moisture conditions. Despite the water resistance of the main materials used for fabrics manufacturing, the change of the mechanical properties caused by the influence of water immersion has been noticed. The reduction in the tensile strength resulting under waterlogged is observed in the range from 5% to 16% depending on the type of investigated coated woven fabric and direction of weft or warp.

  • Inhibitive effect of sodium molybdate on corrosion of AZ31 magnesium alloy in chloride solutions
    • Maria Osipenko
    • Dmitry Kharitonov
    • Aliaksandr Kasach
    • Jacek Ryl
    • Janusz Adamiec
    • Irina Kurilo
    2022 ELECTROCHIMICA ACTA

    In this work, corrosion inhibition of the AZ31 magnesium alloy was investigated in NaCl solutions containing different amounts of sodium molybdate inhibitor. Electrochemical, hydrogen evolution, microscopic, and spectroscopic experiments were utilized to examine the mechanism of corrosion inhibition by molybdates. The results showed that Na2MoO4 inhibitor provides reliable inhibition at high concentrations (150 mM). Surface examination by Raman and XPS spectroscopy confirmed the formation of a protective surface layer of mixed Mo(VI, V, IV) species. Based on these results, the mechanism of corrosion inhibition of the AZ31 alloy by aqueous molybdates was proposed.

  • Inhibitors of glucosamine-6-phosphate synthase as potential antimicrobials or antidiabetics – synthesis and properties
    • Joanna Stefaniak
    • Michał Nowak
    • Marek Wojciechowski
    • Sławomir Milewski
    • Andrzej Skwarecki
    2022 Pełny tekst JOURNAL OF ENZYME INHIBITION AND MEDICINAL CHEMISTRY

    Glucosamine-6-phosphate synthase (GlcN-6-P synthase) is known as a promising target for antimicrobial agents and antidiabetics. Several compounds of natural or synthetic origin have been identified as inhibitors of this enzyme. This set comprises highly selective L-glutamine, amino sugar phosphate or transition state intermediate cis-enolamine analogues. Relatively low antimicrobial activity of these inhibitors, poorly penetrating microbial cell membranes, has been improved using the pro-drug approach. On the other hand, a number of heterocyclic and polycyclic compounds demonstrating antimicrobial activity have been presented as putative inhibitors of the enzyme, based on the results of molecular docking to GlcN-6-P synthase matrix. The most active compounds of this group could be considered promising leads for development of novel antimicrobial drugs or antidiabetics, provided their selective toxicity is confirmed.

  • Inline Microstrip Bandpass Filter With Two Transmission Zeros and Increased Order Using Spurious Resonance of Frequency-Dependent Inverter
    • Maciej Jasiński
    • Muhammad Yameen Sandhu
    • Adam Lamęcki
    • Roberto Gómez-García
    • Michał Mrozowski
    2022 Pełny tekst

    A design method for a class of fourth-order inline microstrip bandpass filter with two transmission zeros and 20% fractional bandwidth is presented. The filter consists of two quarter-wavelength transmission-line resonators coupled by a frequency-dependent inverter. The inverter is composed of two open-ended stubs that are connected by an interdigital capacitor and introduces two poles and two transmission zeros in the filter response. One of these poles is obtained from the spurious resonance of the capacitor, which leads to a very compact filter structure. An equivalent circuit model of the frequencydependent inverter is provided along with a detailed couplingmatrix-based synthesis procedure to design the filter prototype. The design theory is validated with a constructed 2-GHz proofof-concept prototype. Measured results are in close agreement with the synthesis and EM-simulated ones, hence verifying the devised design approach.

  • Inline Microwave Filters With N+1 Transmission Zeros Generated by Frequency-Variant Couplings: Coupling-Matrix-Based Synthesis and Design
    • Martyna Mul
    • Maciej Jasiński
    • Adam Lamęcki
    • Roberto Gómez-García
    • Michał Mrozowski
    2022 Pełny tekst IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS

    A general coupling-matrix-based synthesis methodology for inline Nth-order microwave bandpass filters (BPFs) with frequency-variant reactive-type couplings that generate N+1 transmission zeros (TZs) is presented in this brief. The proposed approach exploits the formulation of the synthesis problem as three inverse nonlinear eigenvalue problems (INEVPs) so that the coupling matrix is built from their sets of eigenvalues. For this purpose, an optimization nonlinear least-squares procedure is employed. The theoretical foundations of the engineered INEVP coupling-matrix-based synthesis framework are described. In addition, its effectiveness is verified through various synthesis examples of a third-order BPF with four TZs based on different circuit models. Moreover, as experimental validation, a 2.4-GHz microstrip prototype of the distributed-element BPF synthesis example is built and measured.

  • Innovative Bidirectional Isolated High-Power Density On-Board Charge for Vehicle-to-Grid
    • Roman Hrbáč
    • Libor Hrdina
    • Vaclav Kolar
    • Zdenek Slanina
    • Vojtech Blazek
    • Tomas Vantuch
    • Mikołaj Bartłomiejczyk
    • Stanislav Misak
    2022 Pełny tekst SENSORS

    This paper deals with developing and implementing a bidirectional galvanically isolated on-board charger of a high-power density. The power density of the new charger was 4 kW/kg and 2.46 kW/dm3, and the maximum efficiency was 96.4% at 3.4 kW. Due to the requirement to achieve a high-power density, a single-stage inverter topology was used. Regarding switching losses, due to the topology of the circuit with so-called hard switching, the switching frequency was set to 150 kHz. A laboratory prototype was built to verify the properties and operating principles of the described charger topology. The on-board charger has been tested in a microgrid test platform. Due to the parasitic properties of the transformer and other electronic components, overvoltage with subsequent oscillations occurred on the primary side of the transformer and damped resonance on its secondary side. These parasitic properties caused interference and especially voltage stress on the semiconductor elements. These undesirable phenomena have been eliminated by adding an active element to the charger topology and a new transistor control strategy. This new switching control strategy of transistors has been patented.

  • Innowacyjne zastosowanie betonu jamistego PERVIA, jako warstwy odsączającej w tunelu na węźle MPL Okęcie w Warszawie
    • Michał Kałużyński
    • Anna Banaś
    • Andrzej Kuryłowicz
    2022 Pełny tekst

    Choć beton jamisty jest stosowany w budownictwie od wielu lat, to mimo swoich wyjątkowych właściwości filtracyjnych jest często niedocenianym elementem budowlanym. Wynika to z jego niewystarczającej wytrzymałości, która spowodowana jest brakiem frakcji piaskowej. Patrząc na problem z drugiej strony, właściwe odwodnienie nawierzchni komunikacyjnych jest podstawowym zadaniem, które musi rozwiązać projektant. Szybkie odprowadzenie wody z powierzchni drogi jest niezbędne, gdyż odpowiada za prawidłową przyczepność opony do nawierzchni, a tym samym za bezpieczeństwo ruchu drogowego. W przedstawionym w niniejszej pracy tunelu, ze względu na uwarunkowania konstrukcyjne, w tym niewielką wysokość skrajni drogowej, poszukiwano rozwiązania, które będzie optymalne zarówno pod względem szybkiego odprowadzania wody, jak i zapewnienia odpowiedniej wytrzymałości i zapobiegania powstawaniu kolein w nawierzchni. Zdecydowano się na zastosowanie betonu jamistego PERVIA jako podbudowy i warstwy filtracyjnej jezdni asfaltowej. To innowacyjne rozwiązanie nie tylko rozwiązało problem przesiąkania wody przez płytę denną, ale także sprzyja odpowiedzialnej gospodarce wodnej, zwiększając poziom wód gruntowych i zachowując równowagę ekologiczną.

  • Innowacyjny system do lokalizacji zasobów dla poprawy efektywności i bezpieczeństwa w służbie zdrowia
    • Mateusz Rzymowski
    • Mateusz Groth
    • Krzysztof Nyka
    • Łukasz Kulas
    2022 Pełny tekst Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Przedstawiono innowacyjne podejście do lokalizacji wewnątrzbudynkowej, które może zostać wykorzystane do podniesienia bezpieczeństwa i efektywności w służbie zdrowia. Opiera się ono na stacjach bazowych pracujących w standardzie Bluetooth Low Energy (BLE), wykorzystujących dedykowany moduł bezprzewodowy. zawierający układ scalony Nordic Semiconductor nRF5284 oraz na antenach rekonfigurowalnych, w których możliwe jest elektryczne przełączanie kierunku wiązki głównej. Zaproponowany algorytm lokalizacji umożliwia odnajdywanie nieznanych pozycji etykiet radiowych BLE, używając wyłącznie mocy sygnału odebranego bez wykonywania dodatkowych wcześniejszych kalibracji i wykorzystując tylko pojedynczą stację bazową oraz etykiety referencyjne BLE przyczepione do ścian. Pomiary wykonane w rzeczywistym środowisku wewnątrz budynku pokazują, że zaproponowane podejście z powodzeniem może zostać wykorzystane w obszarze służby zdrowia i zapewnia wyniki lokalizacji na akceptowalnym poziomie przy jednoczesnym niskim poziomie całkowitych kosztów instalacji oraz utrzymania systemu w porównaniu do komercyjnie dostępnych systemów lokalizacji.

  • In-Reactor Polypropylene Functionalization─The Influence of Catalyst Structures and Reaction Conditions on the Catalytic Performance
    • Miloud Bouyahyi
    • Lidia Jasińska-Walc
    • Rob Duchateau
    • Muhammad Naseem Akhtar
    • E. A. Jaseer
    • Rajesh Theravalappil
    • Nestor Garcia
    2022 Pełny tekst MACROMOLECULES

    To unravel the relationship between silylene-bridged metallocene catalyst structures and polymerization conditions and their effect on the performance in in-reactor functionalization of polypropylene, the behaviors of rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2/MMAO, rac-Me2Si(Ind)2ZrCl2, rac-Me2Si(2-Me-4-Ph-Ind)2HfCl2, and rac-Me2Si(Ind)2HfCl2 in propylene/aluminum alkyl-passivated 10-undecen-1-ol copolymerization were compared. Kinetic analysis revealed higher catalytic activities for zirconocenes compared to analogous hafnocenes. Both the zirconocene and hafnocene with substituted indenyl ligands afforded a higher molecular weight capability, improved stereo-selectivity, and enhanced ability to incorporate functionalized comonomers compared to their non-substituted congeners. An in-depth study of polypropylene functionalization using the best performing catalyst system, rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2/MMAO, at temperatures ranging from 40 to 100 °C, revealed a linear inversely proportional correlation of polymerization temperature with functionalized comonomer reactivity (↑Tp → ↓ r1), copolymer molecular weight (↑Tp → ↓Mn), and melting temperature (↑Tp → ↓Tm). While performing well under standard laboratory polymerization conditions, rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2/MMAO showed limited molecular weight and stereo-selectivity capabilities under high-temperature (130–150 °C) solution process conditions. Although immobilization of rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 onto silica, allowing it to be used under industrially relevant slurry and gas-phase conditions, led to an active catalyst, it failed to incorporate any functionalized comonomer.

  • Insight into Potassium Vanadates as Visible-Light-Driven Photocatalysts: Synthesis of V(IV)-Rich Nano/Microstructures for the Photodegradation of Methylene Blue
    • Małgorzata Nadolska-Dawidowska
    • Mariusz Szkoda
    • Konrad Trzciński
    • Paweł Niedziałkowski
    • Jacek Ryl
    • Aleksandra Dorota Mielewczyk-Gryń
    • Karolina Górnicka
    • Marta Prześniak-Welenc
    2022 Pełny tekst INORGANIC CHEMISTRY

    Photocatalysis is regarded as a promising tool for wastewater remediation. In recent years, many studies have focused on investigating novel photocatalysts driven by visible light. In this study, K2V6O16·nH2O nanobelts and KV3O8 microplatelets were synthesized and investigated as photocatalysts. Samples were obtained via the facile method based on liquid-phase exfoliation with ion exchange. By changing the synthesis temperature (20–80 °C), different compositions, morphologies, and V4+/V5+ ratios were obtained and investigated as photocatalysts for organic dye degradation. Potassium vanadates’ structural, morphological, and optical properties were characterized using X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Physical Property Measurement System (PPMS), thermogravimetric analysis (TGA) with mass spectrometry (MS), N2 adsorption, scanning electron microscopy (SEM), photoluminescence (PL), and UV–vis diffuse reflectance spectroscopy (DRS). Synthesized K2V6O16·nH2O and KV3O8 showed an efficient absorption in the visible wavelength region with a narrow band gap energy of 1.80 and 1.91 eV, respectively. Their photocatalytic activity was evaluated by the degradation of methylene blue (MB) under simulated solar light illumination. The KV3O8 microplatelets exhibited the greatest photocatalytic activity, resulting in more than 90% degradation of the dye within the first 30 min. It is suggested that the observed excellent photocatalytic performance is attributed to the high content of V4+ species. Furthermore, the influence of active species was investigated, and the mechanism responsible for the photodegradation of the MB dye was discussed for the first time for potassium vanadates.

  • Insights into Stoichiometry Adjustments Governing the Performance of Flexible Foamed Polyurethane/Ground Tire Rubber Composites
    • Adam Olszewski
    • Paulina Kosmela
    • Wiktoria Żukowska
    • Paweł Wojtasz
    • Mariusz Szczepański
    • Mateusz Barczewski
    • Łukasz Zedler
    • Krzysztof Formela
    • Aleksander Hejna
    2022 Pełny tekst Polymers

    Polyurethanes (PU) are widely applied in the industry due to their tunable performance adjusted by changes in the isocyanate index—stoichiometric balance between isocyanate and hydroxyl groups. This balance is affected by the incorporation of modifiers of fillers into the PU matrix and is especially crucial for PU foams due to the additional role of isocyanates—foaming of the material. Despite the awareness of the issue underlined in research works, the contribution of additives into formulations is often omitted, adversely impacting foams’ performance. Herein, flexible foamed PU/ground tire rubber (GTR) composites containing 12 different types of modified GTR particles differing by hydroxyl value (LOH) (from 45.05 to 88.49 mg KOH/g) were prepared. The impact of GTR functionalities on the mechanical, thermomechanical, and thermal performance of composites prepared with and without considering the LOH of fillers was assessed. Formulation adjustments induced changes in tensile strength (92–218% of the initial value), elongation at break (78–100%), tensile toughness (100–185%), compressive strength (156–343%), and compressive toughness (166–310%) proportional to the shift of glass transition temperatures (3.4–12.3 °C) caused by the additional isocyanates’ reactions yielding structure stiffening. On the other hand, formulation adjustments reduced composites’ thermal degradation onset due to the inferior thermal stability of hard segments compared to soft segments. Generally, changes in the composites’ performance resulting from formulation adjustments were proportional to the hydroxyl values of GTR, justifying the applied approach.