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  • Implementation of Extended Kalman Filter with Optimized Execution Time for Sensorless Control of a PMSM Using ARM Cortex-M3 Microcontroller
    • Justas Dilys
    • Voitech Stankevič
    • Krzysztof Łuksza
    2021 Pełny tekst ENERGIES

    This paper addresses the implementation and optimization of an Extended Kalman Filter (EKF) for the Permanent Magnet Synchronous Motor (PMSM) sensorless control using an ARM Cortex-M3 microcontroller. A various optimization levels based on arithmetic calculation reduction was implemented in ARM Cortex-M3 microcontroller. The execution time of EKF estimator was reduced from 260.4 μs to 37.7 μs without loss of accuracy. To further reduce EKF execution time, the separation of a Kalman gain and covariance matrices calculation from prediction and measurement state update, a novel method was proposed, and the performance of it an EKF estimator with separation of a Kalman gain and covariance matrices calculation from prediction and measurement state update was analyzed. Simulation and experiments results validate that the proposed technique could provide the same accuracy with less computation time. A tendency of minimum Kalman gain and covariance matrices calculation frequency from rotor electrical frequency was analyzed and are presented in the paper.

  • Implementation of Haar wavelet, higher order Haar wavelet, and differential quadrature methods on buckling response of strain gradient nonlocal beam embedded in an elastic medium
    • Subrat Kumar Jena
    • S. Chakraverty
    • Mohammad Malikan
    2021 Pełny tekst ENGINEERING WITH COMPUTERS

    The present investigation is focused on the buckling behavior of strain gradient nonlocal beam embedded in Winkler elastic foundation. The first-order strain gradient model has been combined with the Euler–Bernoulli beam theory to formulate the proposed model using Hamilton’s principle. Three numerically efficient methods, namely Haar wavelet method (HWM), higher order Haar wavelet method (HOHWM), and differential quadrature method (DQM) are employed to analyze the buckling characteristics of the strain gradient nonlocal beam. The impacts of several parameters such as nonlocal parameter, strain gradient parameter, and Winkler modulus parameter on critical buckling loads are studied effectively. The basic ideas of the numerical methods, viz. HWM, HOHWM, and DQM are presented comprehensively. Also, a comparative study has been conducted to explore the effectiveness and applicability of all the three numerical methods in terms of convergence study. Finally, the results, obtained by this investigation, are validated properly with other works published earlier.

  • Implementation of International Standards of Fiscal and Monetary Transparency - Case of Poland
    • Maria Jastrzębska
    2021

    Research background: Financial managers, investors, lenders, counterparties and citizens should have useful, reliable, timely, complete, comparable, readable information on fiscal and monetary policy. The actions taken and instruments used by fiscal and monetary authorities have an important impact on economic conditions. Purpose of the article: The aim of the article is to assess Poland's compliance with international standards of fiscal transparency and central bank transparency. Research methods: qualitative and descriptive analysis and inductive, deductive reasoning were applied. Findings: Raising the level of fiscal and monetary transparency is supported by compliance with international standards. In Poland, the level of monetary transparency is higher than that of fiscal transparency, with a lack of transparent information about the effects of unconventional state financial policy instruments on the economy and society.

  • Implementation of Non-Probabilistic Methods for Stability Analysis of Nonlocal Beam with Structural Uncertainties
    • Subrat Kumar Subrat
    • S. Chakraverty
    • Mohammad Malikan
    2021 Pełny tekst ENGINEERING WITH COMPUTERS

    In this study, a non-probabilistic approach based Navier’s Method (NM) and Galerkin Weighted Residual Method (GWRM) in term of double parametric form has been proposed to investigate the buckling behavior of Euler-Bernoulli nonlocal beam under the framework of the Eringen's nonlocal elasticity theory, considering the structural parameters as imprecise or uncertain. The uncertainties in Young’s modulus and diameter of the beam are modeled in terms of Triangular Fuzzy Numbers (TFN). The critical buckling loads are calculated for Hinged-Hinged (HH), Clamped-Hinged (CH), and Clamped-Clamped (CC) boundary conditions and these results are compared with the deterministic model in special cases, demonstrating robust agreement. Further, a random sampling technique based method namely, Monte Carlo Simulation Technique (MCST) has been implemented to compute the critical buckling loads of uncertain systems. Also, the critical buckling loads obtained from the uncertain model in terms of Lower Bound (LB) and Upper Bound (UB) by the non-probabilistic methods, viz. Navier’s Method (NM) and Galerkin Weighted Residual Method (GWRM), are again verified with the Monte Carlo Simulation Technique (MCST) with their time periods, demonstrating the efficacy, accuracy, and effectiveness of the proposed uncertain model. A comparative study is also carried out among the non-probabilistic methods and Monte Carlo Simulation Technique (MCST) to demonstrate the effectiveness of methods with respect to time. Additionally, a parametric study has been performed to display the propagation of uncertainties into the nonlocal system in the form of critical buckling loads.

  • Implementation of SiN thin film in fiber-optic sensor working in telecommunication range of wavelengths
    • Sandra Pawłowska
    • Jakub Gierowski
    • Bartłomiej Stonio
    • Marcin Juchniewicz
    • Mateusz Ficek
    • Michał Kruczkowski
    • Małgorzata Szczerska
    2021 Pełny tekst Scientific Reports

    Mirrors are used in optical sensors and measurement setups. This creates a demand for mirrors made of new materials and having various properties tailored to specific applications. In this work, we propose silicon covered with a thin silicon nitride layer as a mirror for near-infrared measurements. SiN layer was deposited on a standard silicon wafer with a Low-Pressure Chemical Vapor Deposition furnace. Then, the created layer was investigated using ellipsometry and scanning electron microscope. Subsequently, the mirror was used as a reflecting surface in a Fabry–Perot fiber-optic interferometer. The mirror performance was investigated for wavelengths used in telecomunication (1310 nm and 1550 nm) and then compared with results obtained with the same measurement setup, with a silver mirror instead of silicon covered with SiN, as reference. Results showed that the proposed mirror can replace the silver one with satisfying results for investigated wavelengths.

  • Implementation of the Concept of Flexicurity in the Selected Countries of Central Eastern Europe
    • Dagmara Nikulin
    • Małgorzata Gawrycka
    2021 Ekonomista

    The CEE countries have to create their own flexicurity policies which would take into account the employment policy guidelines, cultural traditions and socio-economic development. The aim of this article is to examine and evaluate the implementation of the flexicurity concept on the basis of the adopted set of composite indicators. The study covers 9 countries of the CEE region, and the research period covers the years 2007 and 2013. A review of previous research has demonstrated that there are no studies which would take into account a wide range of indicators included in the composite index of flexicurity. Moreover, in the case of CEE countries there is a lack of publications which would compare the degree of flexibility and security of their labour markets or studies that would compare flexicurity indicators for two different moments in time. This article tries to fill this research gap. The analysis of a composite indicator of flexicurity and its component elements shows large differences in the implementation of the flexicurity concept in the individual CEE countries. The labour market in the CEE countries is still characterized by high strictness of Employment Protection Legislation, which adversely affects the outcomes of the labour market. On the other hand, CEE countries have made great efforts in increasing the role of active labour market policies and non-standard forms of work in the last decade. In most of the countries studied the problem is still related to a relatively small share of individuals engaged in life-long learning and to ensuring the security of those working on non-standard employment contracts.

  • Importance of Bile Composition for Diagnosis of Biliary Obstructions
    • Łukasz Krupa
    • Robert Staroń
    • Dorota Dulko
    • Natalia Łozińska
    • Alan Mackie
    • Neil Rigby
    • Adam Macierzanka
    • Aleksandra Markiewicz
    • Christian Jungnickel
    2021 Pełny tekst MOLECULES

    Determination of the cause of a biliary obstruction is often inconclusive from serum analysis alone without further clinical tests. To this end, serum markers as well as the composition of bile of 74 patients with biliary obstructions were determined to improve the diagnoses. The samples were collected from the patients during an endoscopic retrograde cholangiopancreatography (ERCP). The concentration of eight bile salts, specifically sodium cholate, sodium glycocholate, sodium taurocholate, sodium glycodeoxycholate, sodium chenodeoxycholate, sodium glycochenodeoxycholate, sodium taurodeoxycholate, and sodium taurochenodeoxycholate as well as bile cholesterol were determined by HPLC-MS. Serum alanine aminotransferase (ALT), aspartate transaminase (AST), and bilirubin were measured before the ERCP. The aim was to determine a diagnostic factor and gain insights into the influence of serum bilirubin as well as bile salts on diseases. Ratios of conjugated/unconjugated, primary/secondary, and taurine/glycine conjugated bile salts were determined to facilitate the comparison to literature data. Receiver operating characteristic (ROC) curves were determined, and the cut-off values were calculated by determining the point closest to (0,1). It was found that serum bilirubin was a good indicator of the type of biliary obstruction; it was able to differentiate between benign obstructions such as choledocholithiasis (at the concentration of >11 µmol/L) and malignant changes such as pancreatic neoplasms or cholangiocarcinoma (at the concentration of >59 µmol/L). In addition, it was shown that conjugated/unconjugated bile salts confirm the presence of an obstruction. With lower levels of conjugated/unconjugated bile salts the possibility for inflammation and, thus, neoplasms increase.

  • Importance of Conjugation of the Bile Salt on the Mechanism of Lipolysis
    • Natalia Łozińska
    • Christian Jungnickel
    2021 Pełny tekst MOLECULES

    We aim to advance the discussion on the significance of the conjugation of bile salts (BS) in our organism. We hypothesize that conjugation influences the rate of lipolysis. Since the rate of lipolysis is a compound parameter, we compare the effect of conjugation on four surface parameters, which contribute to the rate. Since deconjugation is due to gut microbiota, we hypothesize that microbiota may affect the rate of lipolysis. A meta-analysis of literature data of critical micelle concentration, β, aggregation number, and molar solubilization ratio has been performed for the first time. In addition, critical micelle concentration (CMC), interfacial tension, and lipolysis rate measurements were performed. It was found that the unconjugated BS in mixed micelles increases the antagonism between the BS, therefore, increasing the CMC. This correlated with the effect of unconjugated BS on the solubilization capacity of mixed micelles. The collected literature information indicates that the role of the BS and its conjugation in our organism is a key factor influencing the functioning of our organism, where too high levels of unconjugated BS may lead to malabsorption of fat-soluble nutrients. The experimental lipolysis results irrevocably showed that conjugation is a significant factor influencing the rate.

  • Improved Design Closure of Compact Microwave Circuits by Means of Performance Requirement Adaptation
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    • Leifur Leifsson
    2021

    Numerical optimization procedures have been widely used in the design of microwave components and systems. Most often, optimization algorithms are applied at the later stages of the design process to tune the geometry and/or material parameter values. To ensure sufficient accuracy, parameter adjustment is realized at the level of full-wave electromagnetic (EM) analysis, which creates perhaps the most important bottleneck due to the entailed computational expenses. The cost issue hinders utilization of global search procedures, whereas local routines often fail when the initial design is of insufficient quality, especially in terms of the relationships between the current and the target operating frequencies. This paper proposes a procedure for automated adaptation of the performance requirements, which aims at improving the reliability of the parameter tuning process in the challenging situations as described above. The procedure temporarily relaxes the requirements to ensure that the existing solution can be improved, and gradually tightens them when close to terminating the optimization process. The amount and the timing of specification adjustment is governed by evaluating the design quality at the current design, and the convergence status of the algorithm. The proposed framework is validated using two examples of microstrip components (a coupler and a power divider), and shown to well handle design scenarios that turn infeasible for conventional approaches, in particular, when decent starting points are unavailable.

  • Improved Modeling of Microwave Structures Using Performance-Driven Fully-Connected Regression Surrogate
    • Sławomir Kozieł
    • Peyman Mahouti
    • Nurullah Calik
    • Mehmet Belen
    • Stanisław Szczepański
    2021 Pełny tekst IEEE Access

    Fast replacement models (or surrogates) have been widely applied in the recent years to accelerate simulation-driven design procedures in microwave engineering. The fundamental reason is a considerable—and often prohibitive—CPU cost of massive full-wave electromagnetic (EM) analyses related to solving common tasks such as parametric optimization or uncertainty quantification. The most popular class of surrogates are data-driven models, which are fast to evaluate, versatile, and easy to handle. Notwithstanding, the curse of dimensionality as well as the utility demands (e.g., so that the model covers sufficiently broad ranges of the system operating conditions), limit the applicability of conventional methods. A performance-driven modeling paradigm allows for mitigating these issue by focusing the surrogate setup process in a constrained domain encapsulating designs being of high quality w.r.t. the assumed figures of interest. The nested kriging framework capitalizing on this idea, renders the constrained surrogate using kriging interpolation, and has been shown to surpass traditional approaches. In pursuit of further accuracy improvements, this work incorporates the performance-driven concept into the fully-connected regression model (FRCM). The latter has been recently introduced in the context of frequency selective surfaces, and combined deep neural networks with Bayesian optimization, the latter employed to determine the network architecture and hyper-parameters. Using two examples of miniaturized microstrip couplers, our methodology is demonstrated to outperform both conventional modeling techniques and nested kriging, with reliable models constructed over multi-dimensional parameters spaces using just a few hundreds of samples.

  • Improvement of Oxygen Electrode Performance of Intermediate Temperature Solid Oxide Cells by Spray Pyrolysis Deposited Active Layers
    • Bartosz Kamecki
    • Jakub Karczewski
    • Piotr Jasiński
    • Sebastian Molin
    2021 Advanced Materials Interfaces

    Intermediate temperature solid oxide fuel cells oxygen electrodes are modified by active interfacial layers. Spray pyrolysis is used to produce thin (≈500 nm) layers of mixed ionic and electronic conductors: Sm0.5Sr0.5CoO3−δ (SSC), La0.6Sr0.4CoO3−δ (LSC), La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF), and Pr6O11 (PrOx) on the electrode–electrolyte interface. The influence of the annealing temperature on the electrode polarization (area specific resistance—ASRpol) is investigated by impedance spectroscopy of symmetrical electrodes in the temperature range of 400–700 °C. The results show that the introduction of nanocrystalline interlayers promotes an oxygen reduction reaction by extending the active surface area and improved contact between the electrode and the electrolyte. Introducing LSCF, LSC, or SSC interlayer reduces ASRpol by a factor of 4 and PrOx by a factor of 2 against the reference, powder processed LSCF electrode. At 600 °C, the obtained ASRpol values for PrOx, LSCF, LSC, and SSC interlayer are 245, 137, 119, and 107 mΩ cm2, which can be considered very low in comparison to standard powder processed oxygen electrodes. Anode supported single cell with developed LSC/LSCF electrode reveals ≈1.2 W cm−2 power output at 600 °C and maintains stable cell voltage of 0.75 V under 1 A cm−2 during 60 h of the test.

  • Improvement of the Chimney Effect in Stack Ventilation
    • Romana Antczak-Jarząbska
    • Krzysztof Pawłowski
    • Maciej Niedostatkiewicz
    2021 Pełny tekst Applied Sciences-Basel

    The article is focused on the airflow in a ventilation system in a building. The work examines the methods which enhance the chimney effect. In this paper, three cases with different chimneys were analyzed for the full-scale experiment. These cases were characterized by different geometrical and material parameters, leading to differences in the intensity of the ventilation airflow. The common denominator of the cases was the room with the air inlet and outlet to the ventilation system. The differences between the experimental cases concerned the chimney canal itself, and more precisely its part protruding above the roof slope. The first experimental case concerned a ventilation canal made in a traditional way, from solid ceramic brick. The second experimental case concerned the part that led out above the roof slope with a transparent barrier, called a solar chimney. In the third experimental case, a rotary type of chimney cap was installed on the chimney to improve the efficiency of stack ventilation. All these cases were used to determine the performance of natural ventilation—Air Change per Hour (CH). Additionally, the paper presents a technical and economic comparison of the solutions used.

  • Improvements and Spatial Dependencies in Energy Transition Measures
    • Marta Kuc-Czarnecka
    • Magdalena Olczyk
    • Marek Zinecker
    2021 Pełny tekst ENERGIES

    This article aims to improve one of the newest energy transition measures—the WorldEconomic Forum WEF Energy Transition Index (ETI) and find its driving forces. This paper proposesa new approach to correct the ETI structure, i.e., sensitivity analysis, which allows assessing theaccuracy of variable weights. Moreover, the novelty of the paper is the use the spatial error modelsto estimate determinants of the energy transition on different continents. The results show thatETI is unbalanced and includes many variables of marginal importance for the shape of the finalranking. The variables with the highest weights in ETI did not turn out to be its most importantdeterminants, which means that they differentiate the analysed countries well; nonetheless, theydo not have sufficient properties of approximating the values of the ETI components. The mostimportant components of ETI (with the highest information load) belong to the CO2emissions percapita, the innovative business environment, household electricity prices, or renewable capacitybuildout. Moreover, we identified the clustering of both ETI and its two main pillars in Europe, whichis not observed in America and Asia. The identified positive spatial effects showing that Europeancountries need much deeper cooperation to reach a successful energy transitio

  • Improvements to the STEAM-based teaching of architectural drawing
    • Mateusz Gerigk
    2021 Pełny tekst World Transactions on Engineering and Technology Education

    The author of this article presents a systemic approach to improving the teaching of architectural drawing courses for engineers in the 21st Century. In this era of rapid development of digital technologies, the traditional teaching structure should be redefined to a purpose-oriented dynamic model. The existing, generally accepted teaching models have already proved successfully based on the practice-oriented STEAM programme, which integrates science, technology, engineering, art and mathematics. The systemic approach proposed in the article is a step forward in the teaching model strongly focusing on the open structure of the model necessary for its future development in this changing environment. The usefulness of the proposed model for the improvement of teaching architectural drawing has been analysed along with the syllabus of the Architectural Drawing course in the Faculty of Architecture at Gdańsk University of Technology, Gdańsk, Poland. The results of on-line teaching during the Covid-19 pandemic restrictions were processed by data analysis. The usefulness of the proposed model in different areas of engineering education is discussed in this article.

  • Improving Accuracy of Respiratory Rate Estimation by Restoring High Resolution Features With Transformers and Recursive Convolutional Models
    • Alicja Kwaśniewska
    • Maciej Szankin
    • Jacek Rumiński
    • Anthony Sarah
    • David Gamba
    2021 Pełny tekst

    Non-contact evaluation of vital signs has been becoming increasingly important, especially in light of the COVID- 19 pandemic, which is causing the whole world to examine people’s interactions in public places at a scale never seen before. However, evaluating one’s vital signs can be a relatively complex procedure, which requires both time and physical contact between examiner and examinee. These re- quirements limit the number of people who can be efficiently checked, either due to the medical station throughput, pa- tients’ remote locations or the need for social distancing. This study is a first step to increasing the accuracy of com- puter vision-based respiratory rate estimation by transfer- ring texture information from images acquired in different domains. Experiments conducted with two deep neural net- work topologies, a recursive convolutional model and trans- formers, proved their robustness in the analyzed scenario by reducing estimation error by 50% compared to low resolu- tion sequences. All resources used in this research, including links to the dataset and code, have been made publicly available.

  • Improving Clairvoyant: reduction algorithm resilient to imbalanced process arrival patterns
    • Jerzy Proficz
    • Krzysztof Ocetkiewicz
    2021 Pełny tekst JOURNAL OF SUPERCOMPUTING

    The Clairvoyant algorithm proposed in “A novel MPI reduction algorithm resilient to imbalances in process arrival times” was analyzed, commented and improved. The comments concern handling certain edge cases in the original pseudocode and description, i.e., adding another state of a process, improved cache friendliness more precise complexity estimations and some other issues improving the robustness of the algorithm implementation. The proposed improvements include skipping of idle loop rounds, simplifying generation of the ready set and management of the state array and an about 90-fold reduction in memory usage. Finally an extension enabling process arrival times (PATs) prediction was added: an additional background thread used to exchange the data with the PAT estimations. The performed tests, with a dedicated mini-benchmark executed in an HPC environment, showed correctness and improved performance of the solution, with comparison to the original or other state-of-the-art algorithms.

  • Improving methods to calculate the loss of ecosystem services provided by urban trees using LiDAR and aerial orthophotos
    • Karolina Zięba-kulawik
    • Paweł Hawryło
    • Piotr Wężyk
    • Piotr Matczak
    • Patrycja Przewoźna
    • Adam Inglot
    • Krzysztof Mączka
    2021 URBAN FORESTRY & URBAN GREENING

    In this paper we propose a methodology for combining remotely sensed data with field measurements to assess selected tree parameters (diameter at breast height (DBH) and tree species) required by the i-Tree Eco model to estimate ecosystem services (ES) provided by urban trees. We determined values of ES provided by trees in 2017 in Racibórz (a city in South Poland) and estimated the loss of ES from January 1, 2017 to March 5, 2017, a period of changing legislation that temporarily allowed removal of trees on private property without any permission from city authorities. We applied Canopy Height Models (CHM; GSD 1.0 m) generated from two sets of ALS LiDAR point clouds (acquisitions on June 11, 2011 and March 5, 2017) and performed tree crown segmentations using the GEOBIA approach. Physical attributes were estimated for each tree using predictive models, developed based on field tree inventory . The reference areas for parameterizing the segmentation algorithm and assessing tree species composition were established in Racibórz, while reference data required for assessment of DBH were obtained from the MONIT-AIR project (from Municipality of Kraków). We found that in 2017, 988.79 ha of Racibórz (13.2 % of city area) was covered by the crowns of 264 471 trees, providing ES structural values worth over 384 mil €. The structural value of ES lost in the first months of 2017 (during which 5 075 trees were removed) was about 3.5 mil €. We concluded that in the face of information on tree crown cover that is often missing from city databases, tree inventories require application of a combination of multi-source and multi-resolution spatial analyses, including: administrative decisions for tree removal with exact location, predictive modelling of selected biometrical tree information, automatic crown segmentation on CHM and interpretation of regularly updated color infrared (CIR) aerial orthophotos.

  • Improving social competencies of architecture students through participatory design of marketplace regeneration
    • Justyna Borucka
    • Piotr Czyż
    • Weronika Mazurkiewicz
    • Łukasz Pancewicz
    • Iga Perzyna
    2021 Pełny tekst World Transactions on Engineering and Technology Education

    The article discusses the involvement of architecture students in actual urban regeneration projects through participatory design and tray to respond question how it can improve students social competences, and benefit their future careers as architects and urban planners. By using the example of the student workshops conducted in 2019 at the Faculty of Architecture, GdanskTech, the article discusses the specific methods applied in the participatory process and their impact on the improvement of the social competence of students and the educational benefits of using this methodology in university courses. The student workshops were linked to an ongoing project concerned with regeneration of urban markets across Poland, conducted within the framework of the GOSPOSTRATEG program financed by the National Centre for Research and Development in Poland. Real-life experience of students during participation in enterprises like presented seems to be crucial at attaining high level of social competences. This is even more important in the context of the changing role of the architectural profession in the contemporary complex reality.

  • Improving the regulation of the derivatives market as an objective prerequisite for sustainable development of the global financial system
    • Oksana Novak
    • Oleksandr Melnychenko
    • Oksana Oliinyk
    2021 Pełny tekst E3S Web of Conferences

    The development of financial markets is characterized by the emergence of new financial instruments, in particular derivatives, the risk level analysis of which is complicated. Counterparties are not always fully aware of and do not adequately assess the potential risks of derivatives, which may lead to large financial losses and sometimes bankruptcies. The purpose of the study is to generalize approaches to regulating derivative markets and analyse the adequacy of regulatory influence to ensure sustainable development of the global financial system. The article analyses the approaches of scientists and regulators of the USA and the EU to the regulation of the derivatives market before and after the financial crisis of 2007-2008. Prior to the crisis, most scholars took a liberal approach to derivatives market regulation and recommended monitoring new instruments and not restricting their circulation in any way, emphasizing that effective counterparty risk management and their propensity for self-preservation can prevent excessive risk-taking. The authors analyse the potential risks of derivatives and conclude that exchange-traded derivatives can cause similar processes of liquidity crisis, and, therefore, need additional regulatory tools to ensure the stability of the financial system

  • In Search for Answers: Light4Health Online Course of Health Research for Interior Lighting Design
    • Karolina Zielińska-Dąbkowska
    2021 Pełny tekst ARC Lighting In Architecture

    Three years ago, when I wrote an article in arc called: Human Centric Lighting. The New X Factor? (arc no. 108 Feb/Mar 2019), my intention was to raise questions in relation to the new topic and to find solid, research-based answers in the years to come. Today, I am happy to report that the lighting community, with the Light4Health Online Course of Health Research for Interior Lighting Design, has a useful tool, and consortium members have managed to close the gap between research and practice/application, and translate complex research into an ‘easy to digest’ format for end users.

  • In silico assessment and sonochemical synthesis of 2-alkynyl 3-chloropyrazines as prospective ligands for SARS-CoV-2
    • M.v. Satyanarayana
    • Alugubelli Gopi Reddy
    • M. Yedukondalu
    • Mandava Bhuvan Tej
    • Kazi Hossain
    • Mandava Venkata Basaveswara Rao
    • Manojit Pal
    2021 Pełny tekst JOURNAL OF MOLECULAR STRUCTURE

    The recent global pandemic caused by COVID-19 has triggered an intense effort worldwide towards the development of an effective cure for this disease. In our effort we have explored the 2-alkynyl substituted 3-chloropyrazine framework as a potential template for the design of molecules for this purpose. Our strategy was supported by the in silico studies of representative compounds to assess their binding affinities via docking into the N-terminal RNA-binding domain (NTD) of N-protein of SARS-CoV-2. Thus we created a small library of molecules based on the aforementioned template via an environmentally safer method that involved the rapid synthesis of 2-alkynyl 3-chloropyrazine derivatives under Cu-catalysis assisted by ultrasound. The reactions proceeded via the coupling of 2,3-dichloropyrazine with commercially available terminal alkynes in the presence of CuI, PPh3 and K2CO3 in PEG-400. Further molecular modelling studies helped in establishing a virtual SAR (Structure Activity Relationship) within the series and identification of three potential hits. The desirable ADME was also predicted for these three molecules suggesting their prospective medicinal value.

  • In Vitro Dissolution of Na-Ca-P-Oxynitrides
    • Natalia Wójcik
    • Polina Sinitsyna
    • Sharafat Ali
    • Leena Hupa
    • Bo Jonson
    2021 Pełny tekst Materials

    : Sodium-calcium-phosphate based oxynitride glasses and glass-ceramics doped with Mg, Si, and Nb were studied in vitro in simulated body fluid (SBF) under static conditions. The release of ions and pH changes up to 7 days of immersion were investigated. The nitrogen incorporation into phosphate glass matrix was found to notably influence in vitro dissolution only of homogenous glasses. Increasing the nitrogen content in the samples decreased the mean mass loss, while the niobate incorporation increased it. The correlation between the nitrogen content and increase in pH of SBF was also observed. The presence of phosphates crystallites was found to support the dissolution process at the beginning step (up to 3 days).

  • Inception and Propagation of Electrical Trees in the Presence of Space Charge in HVAC Extruded Cables
    • Mohammad AlShaikh Saleh
    • Shady S. Refaat
    • Marek Olesz
    • Haitham Abu-Rub
    2021 IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION

    This paper presents the space charge impact on the inception and propagation of electrical trees in cross-linked polyethylene (XLPE) insulation via simulations and experimentation. A 3D finite element analysis (FEA)-based modeling is proposed to simulate electrical trees via a needle embedded on the XLPE insulation. The proposed FEA model demonstrates the influence of the space charge magnitude and polarity on the initiation of partial discharges (PD). Then the critical parameters at the tip of an 8 tree are to be examined. Experimentation is necessary to verify the simulation results acquired and study the mechanism of electrical trees at the inception and propagation stage. Therefore, in the experiment, a needle with a curvature radius of 5 is embedded in the XLPE as a method of simulating defects, such as protrusions, voids, or cracks found in cable insulation. The power source supplies several high AC voltages on the 20 kV (rated voltage) cable under test for observing the inception and propagation behavior of the electrical trees. Phase-resolved partial discharge (PRPD) patterns are extracted at the inception and propagation stages of the electrical tree to determine the severity of the PDs occurring. A relationship is obtained for the PD magnitude with respect to the applied AC voltage while considering the positive and negative polarities of the PDs. This relationship then allows for the acquisition of the maximum electric field-tree length characteristics. The goal of the simulation of electrical trees is to provide the reader with a better understanding about the effect of space charge magnitude and polarity to comprehend the behavior of the treeing inception and propagation mechanisms. The injection and extraction of space charges is a complex phenomenon that requires further visualization through simulations. Therefore, the results of both the simulation and experiment are compared with the aim of establishing a clear relationship between space charge distribution and tree initiation.

  • Inclusive Communication Model Supporting the Employment Cycle of Individuals with Autism Spectrum Disorders
    • Michał Tomczak
    • Joanna Maria Szulc
    • Małgorzata Szczerska
    2021 Pełny tekst International Journal of Environmental Research and Public Health

    Difficulties with interpersonal communication experienced by individuals with autism spectrum disorders (ASD) significantly contribute to their underrepresentation in the workforce as well as problems experienced while in employment. Consistently, it is vital to understand how communication within the employment cycle of this group can be improved. This study aims to identify and analyze the possibilities of modifying the communication processes around recruitment, selection, onboarding, and job retention to address the specific characteristics and needs of the representatives of this group. This qualitative study is based on 15 in-depth interviews conducted with 21 field experts, i.e.,: therapists, job trainers, and entrepreneurs employing people with ASD. The findings of this research informed the creation of an inclusive communication model supporting the employment cycle of individuals with ASD. The most important recommendations within the model that was created include the modification of job advertisements, use of less structured job interviews, providing opportunities for mentorship, and supportive and non-direct, electronically mediated communication. To apply the above-mentioned solutions and take full advantage of the talents of people with ASD, it is also necessary to provide tailored sensitivity and awareness training programs for their direct addressees as well as their neurotypical colleagues, including managerial staff.

  • Incorporation of nitrogen in diamond films – A new way of tuning parameters for optical passive elements
    • Monika Kosowska
    • Sandra Pawłowska
    • Kamatchi J Sankaran
    • Daria Majchrowicz
    • Ken Haenen
    • Kishan Dholakia
    • Małgorzata Szczerska
    2021 DIAMOND AND RELATED MATERIALS

    This paper investigates the impact of nitrogen incorporation in diamond films for the construction of an interferometric sensor to measure displacement. Diamond films with different nitrogen levels (0–5%) were deposited on silicon substrates by microwave plasma enhanced chemical vapor deposition. The structural characteristics of these samples are characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), confocal micro-Raman spectroscopy, and electron energy loss spectroscopy (EELS). The homogeneous and continuous surface morphology of the films is observed through SEM. In the micro-Raman and electron energy loss spectroscopy studies, it is evident that there is a formation of sp2 -bonded carbon phases due to the increase in the concentration of nitrogen. This investigation gives a strong basis for utilizing these diamond films as reflective layers in fiber-optic devices. The interferometric measurement setup is constructed as a Fabry-P´erot interferometer. The nitrogen incorporated films are proved to be useful as mirrors as they achieve a measurement signal with high contrast. The achieved visibility values for the investigated samples are higher than 94% in the range of 40–100 μm.

  • Incorporation of the complete ammonia oxidation (comammox) process for modeling nitrification in suspended growth wastewater treatment systems
    • Mohammad Javad Mehrani
    • Lu Xi
    • Przemysław Kowal
    • Dominika Sobotka
    • Jacek Mąkinia
    2021 Pełny tekst JOURNAL OF ENVIRONMENTAL MANAGEMENT

    The newly discovered process complete ammonia oxidation (comammox) has changed the traditional under-standing of nitrification. In this study, three possible concepts of comammox were developed and incorporated as part of an extended two-step nitrification model. For model calibration and validation, two series of long-term biomass washout experiments were carried out at 12 ◦C and 20 ◦C in a laboratory sequencing batch reactor. The inoculum biomass was withdrawn from a large biological nutrient removal wastewater treatment plant. The efficiency of the examined models was compared based on the behaviors of ammonia, nitrite, and nitrate in the studied reactor. Predictions of the conventional approach to comammox, assuming the direct oxidation of ammonia to nitrate, were slightly better than the two other approaches. Simulation results revealed that comammox could be responsible for the conversion of >20% of the influent ammonia load. Therefore, the role of commamox in the nitrogen mass balance in activated sludge systems should not be neglected and requires further investigation. Furthermore, sensitivity and correlation analysis revealed that the maximum growth rates (μ), oxygen half-saturation (KO), and decay rates (b) of the canonical nitrifiers and comammox were the most sen-sitive factors, and the highest correlation was found between μ and b among all considered kinetic parameters. The estimated μ values by the best model were 0.57, 0.11, and 0.15 d.

  • Independent Domination Subdivision in Graphs
    • Ammar Babikir
    • Magda Dettlaff
    • Michael A. Henning
    • Magdalena Lemańska
    2021 Pełny tekst GRAPHS AND COMBINATORICS

    A set $S$ of vertices in a graph $G$ is a dominating set if every vertex not in $S$ is adjacent to a vertex in~$S$. If, in addition, $S$ is an independent set, then $S$ is an independent dominating set. The independent domination number $i(G)$ of $G$ is the minimum cardinality of an independent dominating set in $G$. The independent domination subdivision number $\sdi(G)$ is the minimum number of edges that must be subdivided (each edge in $G$ can be subdivided at most once) in order to increase the independent domination number. We show that for every connected graph $G$ on at least three vertices, the parameter $\sdi(G)$ is well defined and differs significantly from the well-studied domination subdivision number $\sdg(G)$. For example, if $G$ is a block graph, then $\sdg(G) \le 3$, while $\sdi(G)$ can be arbitrary large. Further we show that there exist connected graph $G$ with arbitrarily large maximum degree~$\Delta(G)$ such that $\sdi(G) \ge 3 \Delta(G) - 2$, in contrast to the known result that $\sdg(G) \le 2 \Delta(G) - 1$ always holds. Among other results, we present a simple characterization of trees $T$ with $\sdi(T) = 1$.

  • Independent dynamics of low, intermediate, and high frequency spectral intracranial EEG activities during human memory formation
    • Victoria Marks
    • Krishnakant Saboo
    • Çağdaş Topçu
    • Michał Lech
    • Theodore Thayib
    • Petr Nejedly
    • Vaclav Kremen
    • Gregory A. Worrell
    • Michał Kucewicz
    2021 Pełny tekst NEUROIMAGE

    A wide spectrum of brain rhythms are engaged throughout the human cortex in cognitive functions. How the rhythms of various frequency ranges are coordinated across the space of the human cortex and time of memory processing is inconclusive. They can either be coordinated together across the frequency spectrum at the same cortical site and time or induced independently in particular bands. We used a large dataset of human intracranial electroencephalography (iEEG) to parse the spatiotemporal dynamics of spectral activities induced during formation of verbal memories. Encoding of words for subsequent free recall activated low frequency theta, intermediate frequency alpha and beta, and high frequency gamma power in a mosaic pattern of discrete cortical sites. A majority of the cortical sites recorded activity in only one of these frequencies, except for the visual cortex where spectral power was induced across multiple bands. Each frequency band showed characteristic dynamics of the induced power specific to cortical area and hemisphere. The power of the low, intermediate, and high frequency activities propagated in independent sequences across the visual, temporal and prefrontal cortical areas throughout subsequent phases of memory encoding. Our results provide a holistic, simplified model of the spectral activities engaged in the formation of human memory, suggesting an anatomically and temporally distributed mosaic of coordinated brain rhythms.

  • Indoor accelerated controlled corrosion degradation test of small- and large-scale specimens
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    • Jakub Kowalski
    2021 Pełny tekst OCEAN ENGINEERING

    The work presented here is a part of a long-term project analysing the structural behaviour of ageing marine structures. An accelerated corrosion degradation set-up was developed to reproduce corroded marine structural specimens of different degrees of degradation, controlling various natural factors, i.e., temperature, oxygen content, salinity, and flow velocity. The nine stiffened plates of 1.2 m length and 30 small scale specimens made of mild steel of three different thicknesses have been corroded. The mean corrosion depth and rate have been controlled during the degradation process for all specimens. The corrosion degradation characteristics have been measured and analysed. In the case of small-scale specimens, microscope scanning, and for the stiffened plates, ultrasonic thickness measurements were performed. The obtained corrosion surfaces are highly non-uniform. During the corrosion degradation, a number of measurements were performed to satisfy a confidence level of 95% and an error of 10%. The developed corrosion degradation is compared with a real corrosion depth measurement of ship deck plates of ballast and cargo tanks, showing a very good similarity in the trend and the corrosion acceleration, concluding that the developed corrosion degradation controlled experimental set-up is efficient in reproducing marine structural specimens of different degree of degradation for further mechanical testing.

  • Induction Assisted Hybrid Friction Stir Welding of Dissimilar Materials AA5052 Aluminium Alloy and X12Cr13 Stainless Steel
    • Dhanesh G. Mohan
    • Jacek Tomków
    • S Gopi
    2021 Pełny tekst Advances in Materials Science

    This research aimed to study the induction in-situ heated hybrid friction stir welding (IAFSW) method to join AA5052 aluminium alloy with X12Cr13 stainless steel (SS) to enhance joint strength. The potency of this method on the mechanical properties and microstructural characterizations were also investigated. The results show that the transverse tensile strength gained was 94% of the AA5052 base metal that is 229.5 MPa. This superior strength was achieved due to the annealing that happened to the AA 5052 region and elevated plastic flow in the weld zone by the in-situ induction heating, which resulted in the elongation of the weld region. The microstructure characterization indicates that a refined grain structure was gained in the nugget zone without defects.

  • Influence of alkali metal cations on the photoactivity of crystalline and exfoliated amorphous WO3 – photointercalation phenomenon
    • Mariusz Szkoda
    • Konrad Trzciński
    • Grzegorz Trykowski
    • Marcin Łapiński
    • Anna Lisowska-Oleksiak
    2021 Pełny tekst APPLIED CATALYSIS B-ENVIRONMENTAL

    In order to investigate the effect of photointercalation on photoelectrochemical properties, two types of WO3-based photoanodes, bulk and exfoliated have been prepared and investigated. An aqueous exfoliation method is introduced for the simple fabrication of amorphous and hydrated WO3 nanomaterial using commercial bulk WO3 precursor. The comparison of obtained material with bulk WO3 was performed using Raman, UV–vis, and XPS as well as scanning and transmission electron microscopies. The photoelectrochemical and photocatalytic performances of bulk and exfoliated WO3 were compared. Generally, the proposed exfoliation procedure led to the preparation of photo(electro)catalyst characterized by better performance measured as a photocurrent of water oxidation and rate of methylene blue photodecomposition. The main aim of this research was to investigate the influence of alkali metal cations (Li+,Na+,K+,Cs+) presence in electrolyte on the photocatalytic and photo(electro)catalytic activity of the samples in a form of suspended powder and thin layer on transparent-conductive substrate (FTO), respectively.

  • Influence of Annealing Atmospheres on Photoelectrochemical Activity of TiO2 Nanotubes Modified with AuCu Nanoparticles
    • Wiktoria Lipińska
    • Katarzyna Grochowska
    • Jacek Ryl
    • Jakub Karczewski
    • Siuzdak Katarzyna
    2021 ACS Applied Materials & Interfaces

    In this article, we studied the annealing process of AuCu layers deposited on TiO2 nanotubes (NTs) conducted in various atmospheres such as air, vacuum, argon, and hydrogen in order to obtain materials active in both visible and UV–vis ranges. The material fabrication route covers the electrochemical anodization of a Ti plate, followed by thin AuCu film magnetron sputtering and further thermal treatment. Scanning electron microscopy images confirmed the presence of spherical nanoparticles (NPs) formed on the external and internal walls of NTs. The optical and structural properties were characterized using UV–vis, X-ray diffraction, and X-ray photoelectron spectroscopies. It was proved that thermal processing under the argon atmosphere leads to the formation of a CuAuTi alloy in contrast to materials fabricated in air, vacuum, and hydrogen. The electrochemical measurements were carried out in NaOH using cyclic voltammetry, linear voltammetry, and chronoamperometry. The highest photoactivity was achieved for materials thermally treated in the argon atmosphere. In addition, the Mott–Schottky analysis was performed for bare TiO2 NTs and TiO2 NTs modified with gold copper NPs indicating a shift in the flatband potential. Overall, thermal processing resulted in changes in optical and structural properties as well as electrochemical and photoelectrochemical activities.

  • Influence of Bingham fluid viscosity on energy performances of a vortex chamber pump
    • Andrii Rogovyi
    • Vladimir Korohodskyi
    • Ievgen Medvediev
    2021 ENERGY

    One of the problems in the development of coal-water technologies is the use of reliable and long-lasting pumps. To date, classic pumps, due to the use of mechanical moving parts and seals, are subject to rapid abrasive wear. The solution to this problem can lie in the creation of new vortex chamber pumps developed by the authors. They are highly reliable, simple in design and have no moving parts. The object of this paper consists in determining the range of vortex chamber pump performance when pumping Bingham fluids of different rheological parameters, as well as to determine the dependence of the pump efficiency on the Bingham viscosity and the yield stress. Study of the pump performance was conducted experimentally and with CFD simulation. It was found that an increase in the liquid viscosity reduces the vacuum value near the axis. For the first time it was found that the tenfold increase in plastic viscosity reduces the pump efficiency by about 20%. This results in the fact that the supercharger cannot pump the coal-water slurry with Pa and Pa s. The findings can be extended not only to coal-water slurry, but also to all Bingham fluids.

  • Influence of drying mode and feed per tooth rate on the fine dust creation in pine and beech sawing on a mini sash gang saw
    • Tomasz Rogoziński
    • Daniel Chuchała
    • Marta Pędzik
    • Kazimierz Orłowski
    • Ladislav Dzurenda
    • Tomasz Muziński
    2021 Pełny tekst European Journal of Wood and Wood Products (HOLZ ALS ROH-UND WERKSTOFF)

    The experimental results of the study focused on the effect of drying processes of modified air drying and warm air steam mixture drying of pine and beech wood on the size of sawdust particles created in cutting using PRW-15M sash gang saw, are presented in the paper. Particle size analysis of dry sawdust was performed using two methods—sieving method and laser diffraction analysis. The results showed that the drying process did not affect the general particle size distribution of the sawdust, but the content of very fine dust particles in beech wood sawdust is many times higher when the beech wood was dried in the warm air-steam mixture drying process and sawn at a feed per tooth of 0.105 mm.

  • Influence of effective width of flange on calculation and reinforcement dimensioning of beam of reinforced concrete frame
    • Maciej Solarczyk
    2021 Pełny tekst Budownictwo i Architektura

    The paper analyses the influence of modelling the cross-section of a beam in two-storey reinforced concrete frame of industrial warehouse with dimensions: 18.0 m × 32.0 m using bar elements on the results of bending moments, the value of elastic deflection and the dimensioning of reinforcement due to bending. Six options were considered: a beam as a rectangular section and five T-beam variants with different definitions of effective flange width. The differences in obtained results were commented on. Conclusions useful for the designing of reinforced concrete structures were presented. The procedure for determining the effective flange width in the context of PN-EN 1992-1-1:2008 and PN-B 03264:2002 standards with a commentary on the use of effective flange width in calculations and construction of reinforcement in reinforced concrete structures were described. Brief description of determining the reinforcement due to bending according to the simplified method given in PN-EN 1992-1-1:2008 was presented. In addition, the standard formula for determining the minimum cross sectional area of reinforcement (9.1N) in PN-EN 1992-1-1:2008 with a proposal for its strict determination for the T-beam with the flange in tension was analyzed.

  • Influence of Escherichia coli on Expression of Selected Human Drug Addiction Genes
    • Roman Kotłowski
    2021 Pełny tekst Life

    The impact of enteric microflora on the expression of genes associated with cocaine and amphetamine addiction was described. Human genome-wide experiments on RNA transcripts expressed in response to three selected Escherichia coli strains allowed for significant alteration (p > 0.05) of the linear regression model between HT-29 RNA transcripts associated with the KEGG pathway:hsa05030:Cocaine addiction after 3 h stimulation with intracellular pathogenic E. coli strain UM146 versus non-pathogenic E. coli Nissle 1917. Among the features influenced by the UM146 bacterial strain were visual learning, response to the presence of morphine, response to hypoxia, behavioral fear response and cognitive functions.

  • Influence of Gaps’ Geometry Change on Leakage Flow in Axial Piston Pumps
    • Piotr Patrosz
    2021 Pełny tekst

    Axial piston pumps are the core elements of most medium and high-pressure hydraulic systems. High volumetric efficiency and high working pressures are the main advantages of this type of pumps. Therefore it is necessary to accurately calculate the leakage flow through the gaps to design efficient high-pressure pump. The main difficulty of such calculations is the fact, that the gaps change their geometry during pumping process. The change of gaps’ geometry can be caused by the motion of the pump’s elements or can be pressure-induced. Both of these factors are included in the article. The paper describes the leakage in: a gap between piston and cylinder block, gap in commutation window, gaps in hydrostatic bearings, the gap between commutation plate and cylinder block. The article includes the methodology and results of FEM and CFD simulation of flow through deformed and undeformed gaps. Basing on the CFD results the mathematical models of such gaps were prepared and added to the article.

  • Influence of Gd deposition on the oxidation behavior and electrical properties of a layered system consisting of Crofer 22 APU and MnCo2O4 spinel
    • Tomasz Brylewski
    • Sebastian Molin
    • M. Marczyński
    • Ł. Mazur
    • K. Domaradzki
    • O. Kryshtal
    • A. Gil
    2021 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

    In the study, the surface of the Crofer 22APU ferritic steel was modified with gadolinium oxide nanoparticles and a protective-conducting layer consisting of the MnCo2O4 spinel. This system was studied in the context of application in IT-SOFC interconnects. Four types of samples were studied: unmodified steel, steel coated with a manganese-cobalt spinel layer, steel modified with gadolinium oxide nanoparticles, and a system consisting of steel after both modifications. Steel samples with Gd2O3 nanoparticles were obtained via dip-coating, while the spinel coatings were deposited electrophoretically. All samples were oxidized for 1000 and 2260 h in air at 1073 K. Microstructural and oxidation kinetics studies revealed that gadolinium segregation at grain boundaries in the Cr2O3 scale between the steel and the spinel layer reduces the oxidation rate for the steel/coating system, thereby improving the adhesion of the scale to the substrate. The applied modification decreased the chromium evaporation rate and improved the electrical properties of the interconnect material.

  • Influence of Holes Manufacture Technology on Perforated Plate Aerodynamics
    • Joanna Grzelak
    • Ryszard Szwaba
    2021 Pełny tekst Materials

    Transpiration flow is a very important and still open subject in many technical applications. Perforated walls are useful for the purpose of “flow control”, as well as for the cooling of walls and blades (effusive cooling) in gas turbines. We are still not able to include large numbers of holes in the numerical calculations and therefore we need physical models. Problems are related also to the quality of the holes in perforated plates. The present transpiration analysis concerns with experimental investigations of the air flow through perforated plates with microholes of 125 and 300 µm diameters. A good accordance of the results with other experiments, simulations and theory was obtained. The received results very clearly show that technology manufacturing of plate holes influences on their aerodynamic characteristics. It turned out that the quality of the plate microholes using laser technology and, consequently, the shape of the hole, can affect the flow losses. Therefore, this effect was investigated and the flow characteristics in both directions were measured, i.e., for two plate settings.

  • Influence of Operation Conditions on Temperature Hazard of Lithium-Iron-Phosphate (LiFePO4) Cells
    • Wojciech Kurpiel
    • Bartosz Polnik
    • Łukasz Orzech
    • Krzysztof Lesiak
    • Bogdan Miedziński
    • Marcin Habrych
    • Grzegorz Debita
    • Monika Zamłyńska
    • Przemysław Falkowski-Gilski
    2021 Pełny tekst ENERGIES

    The article presents and discusses the results of research on hazard, especially temperature, for selected lithium-ion-phosphate cells operated in accordance with the manufacturer’s recommendations but used under onerous mining conditions. This applies to the performance of cells in battery sets without the application of any management system (BMS). On the basis of the obtained test results, first of all, the influence of the value of the charging current of cells and the ambient temperature for both free and deteriorated heat exchange, appropriate conclusions and practical recommendations were formulated. This applies especially to threats in the case of random, cyclic, minor overloading, and discharging of the cells.

  • Influence of plasmon resonance on the luminescence of titanium dioxide thin films doped with rare earth ions
    • Marcin Łapiński
    • Jakub Czubek
    • Katarzyna Drozdowska
    • Wojciech Sadowski
    • V V Kuznetsov
    • Nikolay Charykov
    • Barbara Kościelska
    2021 Pełny tekst Journal of Physics : Conference Series

    In this work the study of the optical properties of europium doped titanium dioxide thin films (TiO2:Eu) enhanced by gold plasmonic nanostructures are presented. Plasmonic platforms were manufactured by thermal annealing of thin film of Au, deposited on a Corning glass substrate. As a result of thermal treatment, gold spherical nanostructures with average dimensions of 50 nm were obtained. Luminescent TiO2:Eu film was deposited by RF magnetron sputtering method, from mosaic target. Morphology of gold nanostructures was investigated by SEM and TEM microscopes, while composition of oxides film was analysed by XPS methods. Luminescence properties were studied on the basis of excitation and emission spectra. Experiments have shown that such structures exhibit interesting luminescent properties and could be potential candidates for optoelectronics applications.

  • Influence of preprocessing techniques on pulse pressure velocity determination
    • Artur Poliński
    • Adam Bujnowski
    • Tomasz Kocejko
    • Jerzy Wtorek
    2021

    Pulse Wave Velocity (PWV) is measured and utilized in many clinical applications. Recently, a wide research has been led to develop a cuff-less and continuous blood pressure method basing on PWV. However, in this application a decision on choosing an appropriate fiducial point of pulse wave (PW) waveform is necessary and substantial. It would allow to measure time parameters necessary to determine PWV. An influence of sampling frequency and other preprocessing algorithms on an accuracy of fiducial points determination are discussed in the paper

  • Influence of Properties of Hydraulic Fluid on Pressure Peaks in Axial Piston Pumps’ Chambers
    • Piotr Patrosz
    2021 Pełny tekst ENERGIES

    The article concentrates on the research of the pressure peaks in a working chamber of an axial piston pump. The main focus of the article is the influence of fluid properties on the pressure peaks value. Experimental and analytical methods were used to determine the impact of the fluid density, viscosity, compressibility and aeration. The article describes the pressure peak generation process and explains the theoretical basis of this phenomenon. A model of aerated fluid compression and models of leakage were created using CFD analysis and mathematical equations. These partial models were then merged into one consistent model in Matlab Simulink. The final result was verified by comparing the results obtained from the mathematical model with the results of the experiment. After validation, the model was used to present explicitly how each of the mentioned fluid properties affects the pressure peak value. Additionally, the test stand and measurement equipment used in the experiment were presented along with a short description of the laboratory research and sample results.

  • Influence of rhamnolipids and ionic cross-linking conditions on the mechanical properties of alginate hydrogels as a model bacterial biofilm
    • Natalia Czaplicka
    • Szymon Mania
    • Donata Konopacka-Łyskawa
    2021 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    The literature indicates the existence of a relationship between rhamnolipids and bacterial biofilm, as well as the ability of selected bacteria to produce rhamnolipids and alginate. However, the influence of biosurfactant molecules on the mechanical properties of biofilms are still not fully understood. The aim of this research is to determine the effect of rhamnolipids concentration, CaCl2 concentration, and ionic cross-linking time on the mechanical properties of alginate hydrogels using a Box–Behnken design. The mechanical properties of cross-linked alginate hydrogels were characterized using a universal testing machine. It was assumed that the addition of rhamnolipids mainly affects the compression load, and the value of this parameter is lower for hydrogels produced with biosurfactant concentration below CMC than for hydrogels obtained in pure water. In contrast, the addition of rhamnolipids in an amount exceeding CMC causes an increase in compression load. In bacterial biofilms, the presence of rhamnolipid molecules does not exceed the CMC value, which may confirm the influence of this biosurfactant on the formation of the biofilm structure. Moreover, rhamnolipids interact with the hydrophobic part of the alginate copolymer chains, and then the hydrophilic groups of adsorbed biosurfactant molecules create additional calcium ion trapping sites.

  • Influence of selected CO2 absorption promoters on the characteristics of calcium carbonate particles produced by carbonation of the post-distillation liquid from the Solvay process
    • Natalia Czaplicka
    • Donata Konopacka-Łyskawa
    • Patrycja Lewandowska
    • Marcin Stanisław Łapiński
    • Rafał Tytus Bray
    2021 Pełny tekst POWDER TECHNOLOGY

    The aim of this work is to compare the effect of selected process parameters, gas flow rate, CO2 absorption promoter concentration and its pKa, on the precipitation of CaCO3 by the gas-liquid method using a model post-distillation liquid from the Solvay process. To ensure effective capture of CO2, the absorption promoters used were ammonia, triethanolamine and triethylamine. The Box-Behnken Design was applied to plan the experiments. The analysis of the influence of selected parameters on the course of the process and the characteristics of the obtained products was performed using the response surface methodology. In the studied range of variables, the type of absorption promoter characterized by its pKa has the most significant impact on the reaction time, polymorphic composition of the obtained CaCO3, particle size and their specific surface area. All precipitated CaCO3 samples were highly agglomerated mixture of vaterite and calcite.

  • INFLUENCE OF SOLID PARTICLE CONTAMINATION ON THE WEAR PROCESS IN WATER LUBRICATED MARINE STRUT BEARINGS WITH NBR AND PTFE BUSHES
    • Ewa Piątkowska
    2021 Pełny tekst Polish Maritime Research

    This paper reports on a study of the influence of solid particle contamination on the wear process in water-lubricated slide bearings (steel-acrylonitrile-butadiene rubber (NBR) and steel- polytetrafluoroethylene (PTFE)). To compare the wear of the shaft journal and bushes (NBR and PTFE) when lubricated with fresh water and contaminated water, an experiment was carried out to identify key factors that influence the state of wear of slide bearing. The amount of wear was checked by means of geometric structure measurements on the journals, namely, roughness profile measurements using both a contact profilometer and an optical microscope. The obtained results enabled correlations between the material comprising the sliding sleeve, roughness of the journals and contamination inside the water-lubricated slide bearings.

  • Influence of the femoral offset on the muscles passive resistance in total hip arthroplasty
    • Stanisław Burzyński
    • Agnieszka Sabik
    • Wojciech Witkowski
    • Piotr Łuczkiewicz
    2021 Pełny tekst PLOS ONE

    Background Soft tissue tension is treated as a crucial factor influencing the post-THA dislocation. The femoral offset is regarded as one of the major parameters responsible for the stabilization of the prosthesis. It is unclear which soft tissue is mostly affected by the offset changes. Methods A finite element model of the hip was created. The model comprised muscles, bones, a stem, the acetabular component and a liner. The muscles were modelled as a Hill-type musculo-tendon nonlinear springs. Nonlinear analyses of the hip flexion and internal rotation were performed for the two values of the femoral stem offset. Results We observed that the quadratus femoris and gluteus medius produce the largest resisting moment opposing the external load excreted by the surgeon during the intraoperative hip dislocation test. Conclusions An increased femoral offset increases the stretching of the quadratus femoris muscle significantly and provides the growth of its initial passive force. This muscle serves as a stiff band, providing stabilisation of the hip prosthesis, measured during the simulated intraoperative test.

  • Influence of the fragment size on the recycling process of thin-film modules based on CdTe
    • Anna Kuczyńska-Łażewska
    • Ewa Klugmann-Radziemska
    2021 Pełny tekst Journal of International Scientific Publications

    For several years, the production of second generation cells (the so-called thin film), produced from amorphous silicon, cadmium telluride (CdTe) or copper indium (gallium) diselenide (CI(G)S), has been increasing. The total number of end-of-life panels by 2050 is expected to reach 9.57 million tonnes. They contain heavy metals that can be leached into the environment at the land field. The EU directive on waste electrical and electronic equipment WEEE2, introduced in 2012 obligated producers of photovoltaic panels to be responsible for the waste generated, and also for their disposal. Metal recovery would not only reduce the cost of cell production, but also reduce the consumption of raw materials. Therefore, the development of recycling technology for used and damaged modules of newer generations is important for environmental reasons. The aim of the research is to develop a recycling technology for second generation photovoltaic modules. The work is focused mainly on cells made of CdTe. The developed method can be applied after prior thermal delamination. The efficiency rate of cadmium leaching form the different sized samples depending on different leaching solutions was tested. The next stage will be to develop a technology for the recovery of individual metals from the leaching solution.

  • INFLUENCE OF THE HULL SHAPE ON THE ENERGY DEMAND OF A SMALL INLAND VESSEL WITH HYBRID PROPULSION
    • Artur Karczewski
    • Magdalena Kunicka
    2021 Pełny tekst Polish Maritime Research

    Recently, there has been a significant development of ecological propulsion systems, which is in line with the general trend of environmentally friendly “green shipping”. The main aim is to build a safe, low-energy passenger ship with a highly efficient, emission-free propulsion system. This can be achieved in a variety of ways. The article presents the main problems encountered by designers and constructors already at the stage of designing the unit. The research conducted made it possible to create a design with an effective shape of the hull, with the prospect of an energy-efficient and safe propulsion system with good manoeuvrability. The scope of the research included towing tank tests, recalculation of the results in full-scale objects and a prediction of the energy demand of the propulsion system. The results obtained were compared to indicate power supply variants depending on the hull shape.

  • Influence of the Widespread Use of Corten Plate on the Acoustics of the European Solidarity Centre Building in Gdansk
    • Wojciech Targowski
    • Andrzej Kulowski
    2021 Pełny tekst Buildings

    This paper describes the relationship between a strong architectural vision that is difficult to balance, and user expectations in terms of acoustics. The focus is on the use of corten steel as the dominant finishing material on façades and interiors to achieve an expressive, symbolic message through program-based design. The architectural premises justifying the adopted solutions are presented, especially the universality and homogeneity of the material. Against this background, the influence of corten steel on the acoustics of the two largest rooms of the European Solidarity Center, which are the winter garden and the multi-purpose hall, was discussed. Remedial steps have been taken to reduce the greatest acoustic inconveniences resulting from the widespread use of metal sheet as a finishing material in rooms, i.e., excessive reverberation and a low degree of sound dispersion. A positive result for the acoustic conditions achieved in the winter garden was the presentation of a large body of classical music in the building.