Repozytorium publikacji - Politechnika Gdańska

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Repozytorium publikacji
Politechniki Gdańskiej

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  • Ulepszanie podłoża gruntowego i podtorza z użyciem środków strzałowych
    • Eligiusz Mieloszyk
    • Anita Milewska
    • Mariusz Wyroślak
    2021

    Szybka i skuteczna metoda wzmacniania podłoża gruntowego i podtorza z wykorzystaniem środków strzałowych (zastrzeżona nazwa handlowa: metoda mikrowybuchów) pozwala projektować i budować drogi kolejowe na gruntach o obniżonej nośności (np. tereny podmokłe, bagna, odpady przemysłowe, komunalne, zdegradowane nasypy antropogeniczne). Jest przydatna i godna polecenia przy budowie nowych linii kolejowych, modernizacji istniejących oraz naprawach bieżących i głównych (często powiązanych z modernizacją). Prawidłowo wzmocnione podłoże gruntowe i podtorze jest gwarantem niezawodności danej linii kolejowej. Zwiększa żywotność trasy i bezpieczeństwo prowadzonego ruchu kolejowego.

  • Ultimate compressive strength assessment of uncleaned and cleaned corroded plates with locked crack
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    2021 Pełny tekst Polish Maritime Research

    The work presented here investigates the structural response of cleaned corroded plates, subjected to compressive load in the presence of a locked crack, where the change of mechanical properties as a result of corrosion development and the cleaning process is also accounted for. A Finite Element model for assessing the compressive strength, considering geometric and material nonlinearities, is developed, and the analysed plates are compared with the available experimental data. An experimental design plan is generated using the Design of Experiments techniques, which quantifies the influence of the governing variables and their interactions with respect to the plate's ultimate compressive strength. With a limited number of observations, the most significant effects are identified. The corrosion degradation is revealed to be the most crucial effect leading to an effective strength reduction. It was found that, in the case of a corroded plate with a locked crack subjected to a compressive load, the most severe case is when the crack is transversely oriented. The strength reduction is slightly lower than when the corrosion degradation and the presence of a crack are considered to be a simple summation of these two effects but acting separately. The outcome of the analysis is the development of several empirical formulations that allow a fast estimation of the ultimate strength of a corroded plate, subjected to compressive load in the presence of a locked crack, accounting for different cleaning.

  • Ultimate strength of stiffened plates subjected to compressive load and spatially distributed mechanical properties
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    2021

    The present study deals with the ultimate strength of stiffened plates subjected to spatially distributed mechanical properties and compressive load. Normally, mean values of mechanical properties based on tensile tests are used to validate the numerical assessment with experimental results. However, mechanical properties may vary within a single specimen. To investigate the impact of that, random fields of yield stress and Young modulus are employed together with the FE method. The variations of mechanical properties are estimated based on tensile tests. Different parameters of the random field are analysed, showing that the structural response will be different when compared with the stiffened plate with constant mechanical properties. Finally, it was revealed that the variation of yield stress has a significant impact, and Young modulus uncertainties play a secondary role. It is concluded, that the spatial variation of mechanical properties need to be considered when validating the numerical assessment with experimental measurements.

  • Ultrafiltration Process in Disinfection and Advanced Treatment of Tertiary Treated Wastewater
    • Rafał Bray
    • Katarzyna Jankowska
    • Eliza Kulbat
    • Aneta Łuczkiewicz
    • Aleksandra Sokołowska
    2021 Pełny tekst Membranes

    The paper presents the results of research on the use of ultrafiltration, using membranes of 200 and 400 kDa separation, for disinfection of municipal treated wastewater. The research was conducted on a fractional technical scale using real municipal treated wastewater from two large wastewater treatment plants treating most of the wastewater over the one-million polycentric Gdańsk agglomeration (1.2 million inhabitants). UF 200 kDa and UF 400 kDa processes enabled further improvement of the physical and chemical parameters of treated wastewater. Total phosphorus (to below 0.2 mg/L–UF 200 kDa, 0.13 mg/L–UF 400 kDa) and turbid substances (to below 0.2 mg/L, both membranes) were removed in the highest degree. COD was reduced efficiently (to below 25.6 mgO2/L–UF 200 kDa, 26.8 mgO2/L–UF 400 kDa), while total nitrogen was removed to a small extent (to 7.12 mg/L–UF 200 kDa and 5.7 mg/L–UF 400 kDa. Based on the reduction of indicator bacteria; fecal coliforms including E. coli (FC) and fecal enterococci (FE) it was found that the ultrafiltration is an effective method of disinfection. Not much indicator bacterial were observed in the permeate after processes (UF 200 kDa; FC—5 CFU/L; FE—1 CFU/L and UF 400 kDa; FC—70 CFU/L; FE—10 CFU/L. However, microscopic analysis of prokaryotic cells and virus particles showed their presence after the application of both membrane types; TCN 3.0 × 102 cells/mL–UF 200 kDa, 5.0 × 103 cells/mL–UF 400 kDa, VP 1.0 × 105/mL. The presence of potentially pathogenic, highly infectious virus particles means that ultrafiltration cannot be considered a sufficient disinfection method for treated wastewater diverted for reuse or discharged from high load wastewater treatment plants to recreational areas. For full microbiological safety it would be advisable to apply an additional disinfection method (e.g., ozonation)

  • Ultrasensitive electrochemical determination of the cancer biomarker protein sPD-L1 based on a BMS-8-modified gold electrode
    • Paweł Niedziałkowski
    • Magdalena Bojko
    • Jacek Ryl
    • Anna Wcisło
    • Marta Spodzieja
    • Katarzyna Magiera Mularz
    • Katarzyna Guzik
    • Grzegorz Dubin
    • Tad A. Holak
    • Tadeusz Ossowski
    • Sylwia Rodziewicz-Motowidło
    2021 Pełny tekst BIOELECTROCHEMISTRY

    This work describes the modification of a gold electrode with the BMS-8 compound that interacts with the Programmed Death-Ligand 1 (PD-L1), an immune checkpoint protein. The results show that we can confirm the presence of the sPD-L1 in the concentration range of 10−18 to 10−8 M using electrochemical impedance spectroscopy (EIS) with a limit of detection (LOD) of 1.87 × 10−14 M for PD-L1 (S/N = 3.3) and at a concentration of 10−14 M via cyclic voltammetry (CV). Additionally, high-resolution X-ray photoelectron spectroscopy (XPS), contact angle, and surface free energy measurements were applied to confirm the functionalization of the electrode. We investigated the selectivity of the electrode for other proteins: Programmed Death-1 (PD-1), cluster of differentiation 160 (CD160), and B- and T-lymphocyte attenuator (BTLA) at concentrations of 10−8 M. Differentiation between PD-L1 and PD-1 was achieved based on the analysis of the capacitance effect frequency dispersion at the surface of the modified Au electrode with BMS-8 after incubation at various concentrations of PD-L1 and PD-1 proteins in the range of 10−18 to 10−8 M. Significant differences were observed in the heterogeneity of PD-L1 and PD-1. The results of the quasi-capacitance studies demonstrate that BMS-8 strongly and specifically interacts with the PD-L1 protein.

  • Ultrasonic-assisted Electrodeposition of Cu-Sn-TiO2 Nanocomposite Coatings with Enhanced Antibacterial Activity
    • Dmitry Kharitonov
    • Aliaksandr Kasach
    • Denis Sergievich
    • Angelika Wrzesińska
    • Izabela Bobowska
    • Kazimierz Darowicki
    • Artur Zieliński
    • Jacek Ryl
    • Irina Kurilo
    2021 Pełny tekst ULTRASONICS SONOCHEMISTRY

    Copper-based coatings are known for their high antibacterial activity. In this study, nanocomposite Cu–Sn–TiO2 coatings were obtained by electrodeposition from an oxalic acid bath additionally containing 4 g/dm3 TiO2 with mechanical and ultrasonic agitation. Ultrasound treatment was performed at 26 kHz frequency and 32 W/dm3 power. The influence of agitation mode and the current load on the inclusion and distribution of the TiO2 phase in the Cu–Sn metallic matrix were evaluated. Results indicated that ultrasonic agitation decreases agglomeration of TiO2 particles and allows for the deposition of dense Cu–Sn–TiO2 nanocomposites. It is shown that nanocomposite Cu–Sn–TiO2 coatings formed by ultrasonic-assisted electrodeposition exhibit excellent antimicrobial properties against E. coli bacteria.

  • Ultrasound-assisted wet-impregnation of Ag–Co nanoparticles on cellulose nanofibers: Enhanced catalytic hydrogenation of 4-nitrophenol
    • Vividha K. Landge
    • Shirish H. Sonawane
    • Sivakumar Manickam
    • G.Uday Bhaskar Babu
    • Grzegorz Boczkaj
    2021 Journal of Environmental Chemical Engineering

    In this study, a novel nanocomposite of bimetallic Ag–Co nanoparticles supported on cellulose nanofibers (CNFs) was synthesised using the ultrasound-assisted wet-impregnation method for catalytic applications. CNFs were prepared from cellulose acetate using the electrospinning technique. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the successful synthesis of CNFs. Further, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) revealed a uniform dispersion of Ag and Co metals on the CNFs. At the same time, X-Ray diffraction (XRD) spectra indicated the highly crystalline nature of the as-produced composite. The hydrogenation of 4-nitrophenol (4-NP) was used to study the efficiency of the synthesised nanocomposite. The progress of the reaction was examined via UV–visible spectroscopy. It was noted that Ag-Co nanoparticles supported on CNFs catalysed the hydrogenation of 4-NP (0.1 mM) to 4-aminophenol within just 110 s with an apparent rate constant of 0.0172 s−1. This study proved that the obtained catalysts have superior stability and reusability with about 100% conversion up to 5 cycles. The excellent activity of the as-synthesised Ag-Co/CNFs nanocomposites makes it a promising nanocatalyst for catalytic applications.

  • Understanding Knowledge-Intensive Business Services. Identification, Systematization, and Characterization of Knowledge Flows
    • Małgorzata Zięba
    2021 Pełny tekst

    This book contributes to an improved understanding of knowledge-intensive business services and knowledge management issues. It offers a complex overview of literature devoted to these topics and introduces the concept of ‘knowledge flows’, which constitutes a missing link in the previous knowledge management theories. The book provides a detailed analysis of knowledge flows, with their types, relations and factors influencing them. It offers a novel approach to understand the aspects of knowledge and its management not only inside the organization, but also outside, in its environment.

  • Understanding the capacitance of thin composite films based on conducting polymer and carbon nanostructures in aqueous electrolytes
    • Anita Cymann-Sachajdak
    • Magdalena Graczyk-Zajac
    • Grzegorz Trykowski
    • Monika Wilamowska-Zawłocka
    2021 Pełny tekst ELECTROCHIMICA ACTA

    In this work electrochemical performance of thin composite films consisted of poly(3,4-ethylenedioxythiophene) (PEDOT), graphene oxide (GOx) and oxidized multiwalled carbon nanotubes (oxMWCNTs) is investigated in various sulphates (Li2SO4, Na2SO4, K2SO4, MgSO4) and acidic (H2SO4) electrolytes. Capacitance values, rate capability and cycling stability achieved for the composite layers are correlated with the electrolytes’ properties such as the conductivity, viscosity, cation size and pH. The highest capacitance values are achieved in acidic solution (98.6 mF cm−2 at 1 mA cm−2), whereas cycling stability is better in neutral electrolytes (88.4% of initial capacitance value after 10’000 cycles recorded for symmetric supercapacitor in 0.5 M MgSO4 solution). Diffusion controlled and non-diffusion controlled capacitance contributions are calculated and the results are discussed considering various ranges of sweep rates taken into account in the linear fitting and extrapolation of parameters.

  • Understanding the interactions between protein stabilizers and the peptide bond through the analysis of the volumetric and compressibility properties for the model systems
    • Emilia Kaczkowska
    • Jarosław Wawer
    • Magdalena Tyczyńska
    • Małgorzata Jóźwiak
    • Joanna Krakowiak
    2021 Pełny tekst JOURNAL OF CHEMICAL THERMODYNAMICS

    This work confirms our earlier supposition, that volumetric and acoustic parameters for simple model proposed by us are directly related to stabilizing/destabilizing effect of osmolytes on proteins structure. The apparent molar volumes, V and the apparent molar isentropic compressions, KS,, of glycine and N,N,N –trimethylglycine (betaine) were determined from densities and speed of sound measurements in aqueous solution of N-methylacetamide (as a model of peptide bond of protein). The standard molar parameters for osmolytes were obtained from concentration dependence of the calculated quantities at NMA concentration equal 2, 4, 6 and 8 (mol/kg) and at temperature T = (288.15, 298.15 and 308.15) K. The standard values were combined with volumetric and compressibility data for amino acids in pure water to obtain transfer properties from water to aqueous N-methylacetamide solutions. The standard partial molar volume of transfer of studied osmolytes, 〖Δ_t V〗_Φ^0, seems to be related mainly to hydrophilic/hydrophobic features of molecules. The stabilizing/destabilizing effect of solute on protein structure is reflected in temperature influence on the limiting partial molar quantities.

  • Underwater acoustic communication system using broadband signal with hyperbolically modulated frequency
    • Jan Schmidt
    • Aleksander Schmidt
    2021 Pełny tekst Vibrations in Physical Systems

    The implementation of reliable acoustic underwater communication in shallow waters is a scientific and engineering challenge, mainly due to the permanent occurrence of the multipath phenomenon. The article presents the concept of a transmission system using a broadband signal with hyperbolically modulated frequency (HFM) to transmit data symbols and synchronize data frames. The simulation tests were carried out in channels with Rician fading, reflecting the short- and mediumrange shallow water channels. The simulation also took into account the presence of additive Gaussian noise in the channel on the functioning of the receiver. The obtained results prove the high reliability of the underwater communication system based on broadband HFM signals.

  • Unexpected Z/E isomerism of N-methyl-O-phosphothioyl benzohydroxamic acids, their oxyphilic reactivity and inertness to amines
    • Arkadiusz Majewski
    • Jarosław Chojnacki
    • Witold Przychodzeń
    2021 Pełny tekst STRUCTURAL CHEMISTRY

    Thiophosphinoylation of N-methyl p-substituted benzohydroxamic acids using disulfanes (method A) or diphenylphosphinothioyl chloride (method B) provides only one conformer of the respective O-phosphothioyl derivative (Xray and NMR analysis). Undergoing the P-transamidoxylation reaction is an evidence of the reversibility of thiophosphinoylation. Only those products containing strong EWG substituents in the aroyl residue or bulky substituents at the phosphorus atom possess E conformation. DFT calculations confirmed the energetic domination of each isomer. The Z-isomers are distorted amides having both high degree of nitrogen pyramidalization (38–55°) and amide twist (12–30°). In solution they exist in a defined conformation that is evidenced by the presence of a sharp signal of N-methyl protons at low temperature. They do not isomerize in solutions. Some of them slowly undergo the N-O bond scission above 100 °C. Both isomers are not as sensitive to neutral hydrolysis as twisted amides can be and are inert toward amines. The rate of alkaline hydrolysis can be correlated with pKa of hydroxamic acid. Because of their outstanding oxyphilicity, these compounds can be defined as nerve agent surrogates and safer alternatives of phosphorus fluorides for serine-active enzyme inhibition studies

  • Unity-Gain Zero-Offset CMOS Buffer with Improved Feedforward Path
    • Waldemar Jendernalik
    • Jacek Jakusz
    • Robert Piotr Piotrowski
    • Grzegorz Blakiewicz
    • Stanisław Szczepański
    2021 Pełny tekst Electronics

    A voltage unity-gain zero-offset CMOS amplifier with reduced gain error and increased PSRR (power supply rejection ratio) is proposed. The amplifier uses two feed mechanisms, negative feedback and supporting positive feedforward, to achieve low deviation from unit gain over the entire input range. The circuit, designed in a standard 180-nanometer 1.8-voltage CMOS process, is compared with two known buffers of similar topology, also designed in the same process. Simulations show that, with the same supply (1.8 V), power (1.2 mW), load (12 pF), bandwidth (50 MHz), and similar area (600 m2), the proposed buffer achieves the lowest gain error (0.3%) and the highest PSRR (72 dB).

  • University Students’ Research on Artificial Intelligence and Knowledge Management. A Review and Report of Multi-case Studies
    • Mieczysław Owoc
    • Paweł Weichbroth
    2021 Pełny tekst

    Leading technologies are very attractive for students preparing their theses as the completion of their studies. Such an orientation of students connected with professional experiences seems to be a crucial motivator in the research in the management and business areas where these technologies condition the development of professional activities. The goal of the paper is the analysis of students’ thesis topics defended in the last 10 years in business informatics and computer science in two selected universities in Poland. Our study relies on a detailed review and analysis of qualitative data, obtained from a literature review and multi-case-study research. In the case of the artificial intelligence domain, we have identified six areas of research, namely: general AI, machine learning (ML), natural language processing (NLP), artificial neural networks (ANNs), expert systems, and hybrids. In the case of the knowledge management domain, we have recognized eleven areas of research, regarding the following sectors: e-government, technology, space exploration, social media, manufacturing, healthcare, finance, entertainment, education, e-commerce, and business. Future research will be directed toward extending the scope by including other regions and universities as well as identifying and analyzing students’ motivational factors, associated with research projects and higher education.

  • Uniwersalny Kontroler Radiowy w systemie STRADAR
    • Sylwester Kaczmarek
    • Mariusz Miszewski
    • Marcin Wyczyński
    2021 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Opisano praktyczne rozwiązanie uniwersalnego kontrolera radiowego UKR – jednego z podstawowych elementów funkcjonalnych systemu STRADAR – który obsługuje sensory wykorzystywane na granicy morskiej państwa. Jest on także odpowiedzialny za komunikację personelu Straży Granicznej. UKR ma dwie wersje, jedną mobilną – na jednostki pływające, pojazdy lądowe i jednostki latające, drugą stacjonarną – na stałe punkty obserwacyjne rozmieszczone wzdłuż granicy. Urządzenie to uzyskało pozytywny wynik testów akceptacyjnych oraz badań certyfikacyjnych i osiągnęło IX poziom gotowości technologii.

  • Upamiętnianie w zdecentralizowanej formule
    • Agnieszka Gębczyńska-Janowicz
    2021

    Realizacje kommemoratywne tworzone obecnie w przestrzeni publicznej udowadniają, e definicja pomnika jest niejednoznaczna, wynika z różnych aspektów twórczości i dostosowuje się do kontekstu kulturowego epoki. Celem artykułu jest analiza współczenej realizacji formuły zdecentralizowanej.

  • Uptake, accumulation, and translocation of Zn, Cu, Pb, Cd, Ni, and Cr by P. australis seedlings in an urban dredged sediment mesocosm: impact of seedling origin and initial trace metal content
    • Nicole Nawrot
    • Ewa Wojciechowska
    • Ksenia Pazdro
    • Jacek Szmagliński
    • Janusz Pempkowiak
    2021 Pełny tekst SCIENCE OF THE TOTAL ENVIRONMENT

    The study presents results from 6 months of phytoremediation of sediments dredged from three urban retention tanks carried out in a mesocosm setup with the use of P. australis. Two kinds of P. australis seedlings were considered: seedlings originating from natural (uncontaminated - Suncont) and anthropogenically changed environments (contaminated – Scont); this distinction was reflected in the baseline concentrations of trace metals inside their tissues. The potentially toxic elements (PTEs) considered in this study were as follows: Zn, Cu, Cd, Ni, Cr, and Pb. The aim of the study was to compare the uptake, accumulation, and translocation properties of seedlings with different initial trace metal contents. The PTE concentrations were analyzed in sediments as well as in belowground and aboveground parts of plants in the middle (3rd month) and at the end of the investigation period using inductively coupled plasma mass spectrometry (ICP-MS), and the accumulation of PTEs in plant tissues was calculated. Phytoextraction efficiency was evaluated using the bioconcentration factor (BF) and translocation factor (TF). Plant morphology was assessed with scanning electron microscopy (SEM) to document plant stress due to PTE exposure. The results of our study indicated that P. australis seedlings originating from sites differing in the initial trace metal content exhibited different behavior when grown on sediments dredged from urban retention tanks. Suncont seedlings with low initial metal contents tended to adapt to the dredged sediments and showed phytoextraction ability, while Scont seedlings originating from sites with initial high contents of trace metals acted as phytoexcluders and tended to release PTEs from their tissues into the sediments. The morphological and structural effects caused by metal toxicity were observed in growth limitation, root tissue disturbance, root hair number decrease, and structural alterations in the epidermis and endodermis. Therefore, the Suncont seedlings presented better properties and adaptability for phytoremediation purposes.

  • Urban Lighting Research Transdisciplinary Framework—A Collaborative Process with Lighting Professionals
    • Catherine Vega, Pérez
    • Karolina Zielińska-Dąbkowska
    • Franz Hölker
    2021 Pełny tekst International Journal of Environmental Research and Public Health

    Over the past decades, lighting professionals have influenced the experience of the night by brightly illuminating streets, buildings, skylines, and landscapes 24/7. When this became the accepted norm, a dual perspective on night-time was shaped and the visual enjoyment of visitors after dusk was prioritized over natural nightscapes (nocturnal landscapes). During this time, researchers of artificial light at night (ALAN) observed and reported a gradual increase in unnatural brightness and a shift in color of the night-time environment. As a consequence, ALAN has been identified as a relevant pollutant of aquatic and terrestrial habitats, and an environmental stressor, which may adversely affect a wide range of organisms, from micro-organisms to humans. Unfortunately, lighting professionals and ALAN researchers usually attempt to solve today’s sustainable urban lighting problems distinctive to their fields of study, without a dialogue between research and practice. Therefore, in order to translate research knowledge as an applicable solution for the lighting practice and to minimize the impact on the environment, a collaborative framework involving a transdisciplinary process with lighting professionals is crucial to potentially bring the practice, research, production, decision-making, and planning closer to each other. This paper presents a framework to help reduce the existing gap of knowledge, because appropriate lighting applications depend upon it. Access to less light polluted nightscapes in urban environments is just as important as access to unpolluted water, food, and air. This call for action towards sustainable urban lighting should be included in future lighting policies to solve the urgent environmental and health challenges facing our world.

  • Use of Bi-Temporal ALS Point Clouds for Tree Removal Detection on Private Property in Racibórz, Poland
    • Patrycja Przewoźna
    • Paweł Hawryło
    • Karolina Zięba-kulawik
    • Adam Inglot
    • Krzysztof Mączka
    • Piotr Wężyk
    • Piotr Matczak
    2021 Pełny tekst Remote Sensing

    Trees growing on private property have become an essential part of urban green policies. In many places, restrictions are imposed on tree removal on private property. However, monitoring compliance of these regulations appears difficult due to a lack of reference data and public administration capacity. We assessed the impact of the temporary suspension of mandatory permits on tree removal, which was in force in 2017 in Poland, on the change in urban tree cover (UTC) in the case of the municipality of Racibórz. The bi-temporal airborne laser scanning (ALS) point clouds (2011 and 2017) and administrative records on tree removal permits were used for analyzing the changes of UTC in the period of 2011–2017. The results show increased tree removal at a time when the mandatory permit was suspended. Moreover, it appeared that most trees on private properties were removed without obtaining permission when it was obligatory. The method based on LiDAR we proposed allows for monitoring green areas, including private properties.

  • Using deep learning to increase accuracy of gaze controlled prosthetic arm
    • Tomasz Kocejko
    2021

    This paper presents how neural networks can be utilized to improve the accuracy of reach and grab functionality of hybrid prosthetic arm with eye tracing interface. The LSTM based Autoencoder was introduced to overcome the problem of lack of accuracy of the gaze tracking modality in this hybrid interface. The gaze based interaction strongly depends on the eye tracking hardware. In this paper it was presented how the overall the accuracy can be slightly improved by software solution. The cloud of points related to possible final positions of the arm was created to train Autoencoder. The trained model was next used to improve the position provided by the eye tracker. Using the LSTM based Autoencoder resulted in nearly 3% improvement of the overall accuracy.

  • Using Evidence-based Arguments to Support Dependability Assurance - Experiences and Challenges
    • Janusz Górski
    2021 ACM SIGAda Ada Letters

    The presentation introduces to the problem of evidence-based arguments and their applications. Then, based on the experiences collected during development and commercial deployment of a concrete solution to this problem (system NOR-STA) we overview selected challenges and the ways of addressing them.

  • Using FreeFEM open software for modelling the vibrations of piezoelectric devices
    • Marek Moszyński
    2021 Pełny tekst Vibrations in Physical Systems

    Modelling vibrations of piezoelectric transducers has been a topic discussed in the literature for many decades. The first models - so-called one-dimensional - describe the vibrations only near operating frequency and near its harmonics. Attempts to introduce two-dimensional models were related to the possibility of one transducer working at several frequencies, including both thickness vibrations and those resulting from the transducer horizontal dimensions. In recent decades, thanks to the use of the finite element method and its derivatives, and the progress related to the increase in processor speed and memory availability, the implementation of models based on three-dimensional modelling is possible using software on personal computers. As the implementation of finite element method algorithms is characterized by high complexity, several professional software packages have been created on the commercial market, among which only a few implement the piezoelectric equations. In this context, this article presents how to use open source software along with developed programming language for intuitive definition of piezoelectric equations and its solution.

  • Using the ultrasonic tomography method to study the condition of wooden beams from historical buildngs
    • Monika Zielińska
    • Magdalena Rucka
    2021

    The need to evaluate the integrity of wooden structural elements is constantly increasing. Non-destructive methods are becoming more popular in this field of research. One type of non-destructive testing is the ultrasonic imaging method, which allows the analysis of internal wood structures without disturbing their state and integrity. In this study, we are interested in assessing the effect of wood condition on the ultrasound time of flight (TOF). The research was carried out on wooden beams, which were obtained from a historical building. The images obtained from ultrasound tomography were compared with results of a visual inspection.Places of discontinuities, voids and cracks in wood caused a much lower velocity of wave propagation.The location of the wood core was illustrated by the places with the highest velocity. The article proved the validity of using ultrasonic tomography to assess the technical condition of historic wooden beams.

  • Ustawa a autonomia statutowa w Polsce i w Ukrainie: rozwiązania statutowe w sferze governance wybranych uczelni polskich i ukraińskich
    • Krzysztof Leja
    • Viacheslav Komarov
    • Iryna Degtyarova
    2021

    Kierując się zasadą autonomii uczelni i deregulacji prawa oraz właściwym miejscem statutu w systemie źródeł prawa, w ramach tego rozdziału postanowili-śmy poddać analizie statuty wybranych uczelni w Polsce i w Ukrainie, na tle roz-wiązań ustawowych na podstawie następujących pytań badawczych:• W jaki sposób i w jakim stopniu uczelnie korzystają z uprawnień autonomicznych (w zakresie autonomii organizacyjnej) i potencjału Ustawy w swoich statutach? • Jakie sfery reguluje ustawa, a jakie statut? Czy i w jakim zakresie istnieje do-mniemanie właściwości statutów do regulowania spraw nieobjętych regulacją ustawową?• Czy statut przedstawia bardzo szczegółowe podejście, czy tylko ramy? Czy może statut odzwierciedlać sposób i charakter uczelnianej społeczności aka-demickiej (jako „polityczne” porozumienie wszystkich grup interesów?)

  • Uszkodzenia pożarowe dachu budynku kościoła pw. Świętych Apostołów Piotra i Pawła
    • Tomasz Majewski
    • Maciej Niedostatkiewicz
    2021 Pełny tekst Przegląd Budowlany

    W artykule przedstawionopsi działń podjętych po pożarze dachu zabytkowego Kcioła pw. Świętych Apostołów Piotra i Pawła w Gdańsku

  • Utilizing pulse dynamics for non-invasive Raman spectroscopy of blood analytes
    • Maciej Wróbel
    • Jeong Hee Kim
    • Piyush Raj
    • Ishan Barman
    • Janusz Smulko
    2021 Pełny tekst BIOSENSORS & BIOELECTRONICS

    Non-invasive measurement methods offer great benefits in the field of medical diagnostics with molecular-specific techniques such as Raman spectroscopy which is increasingly being used for quantitative measurements of tissue biochemistry in vivo. However, some important challenges still remain for label-free optical spectroscopy to be incorporated into the clinical laboratory for routine testing. In particular, non-analyte-specific variations in tissue properties introduce significant variability of the spectra, thereby preventing reliable calibration. For measurements of blood analytes such as glucose, we propose to decrease the interference from individual tissue characteristics by exploiting the known dynamics of the blood-tissue matrix. We reason that by leveraging the natural blood pulse rhythm, the signals from the blood analytes can be enhanced while those from the static components can be effectively suppressed. Here, time-resolved measurements with subsequent pulse frequency estimation and phase-sensitive detection are proposed to recover the Raman spectra correlated with the dynamic changes at blood-pulse frequency. Pilot in vivo study results are presented to establish the benefits as well as outline the challenges of the proposed method in terms of instrumentation and signal processing.

  • Validation of Hydraulic Mechanism during Blowout Trauma of Human Orbit Depending on the Method of Load Application
    • Marcin Zmuda Trzebiatowski
    • Paweł Kłosowski
    • Andrzej Skorek
    • Krzysztof Żerdzicki
    • Paweł Lemski
    • Mateusz Koberda
    2021 Pełny tekst Applied Bionics and Biomechanics

    The more we know about mechanisms of the human orbital blowout type of trauma, the better we will be able to prevent them in the future. As long as the buckling mechanism’s veracity is not in doubt, the hydraulic mechanism is not based on equally strong premises. To investigate the correctness of the hydraulic mechanism’s theory, two different methods of implementation of the hydraulic load to the finite element method (FEM) model of the orbit were performed. The intraorbital hydraulic pressure was introduced as a face load applied directly to the orbit in the first variant, while in the second one the load was applied to the orbit indirectly as a set of nodal forces transferred from the external surface of the eyeball via the intraorbital tissues to the orbital walls within the contact problem. Such an approach is aimed at a better understanding of the pattern for the formation of blowout fractures during the indirect load applied to the orbital bones. The nonlinear dynamic analysis of both numerical models showed that the potential fracture was observed in the second variant only, embracing a relatively large area: both medial and lower wall of the orbit. Interestingly, the pressure generated by the intraorbital entities transferred the energy of the impact to the orbital sidewalls mainly; thus, the nature of the mechanism known as the hydraulic was far from the expected hydraulic pressure. According to the eyeball’s deformation as well as the areas of the greatest Huber-Mises-Hencky (H-M-H) stress within the orbit, a new term of strut mechanism was proposed instead of the hydraulic mechanism as more realistic regarding the investigated phenomenon. The results of the current research may strongly influence the development of modern implantology as well as affect forensic medicine.

  • Validation study on a new semi-empirical method for the prediction of added resistance in waves of arbitrary heading in analyzing ship speed trial results
    • Jinbao Wang
    • Sebastian Bielicki
    • Florian Kluwe
    • Hideo Orihara
    • Gongzheng Xin
    • Kenichi Kume
    • Semyun Oh
    • Shukui Liu
    • Peiyuan Feng
    2021 OCEAN ENGINEERING

    This paper describes an open and extensive validation study carried out by the Specialist Committee on Ships in Operation at Sea (SOS) of the International Towing Tank Conference (ITTC) on the newly developed SHOPERA-NTUA-NTU-MARIC (SNNM) wave-added resistance prediction method. The SNNM method aims at a simple, fast and transparent determination of the added resistance in regular waves of arbitrary encounter directions, even when the hull geometry is not available. Prior to the validation study, a series of acceptance criteria for the new method were specified by the committee. Contributions of 1,477 added resistance experimental data samples from 8 institutions were collected, analyzed and cross-checked with satisfactory outcome, which finally led to the inclusion of the new method into the ITTC recommended sea trial procedure as an important progress. Some aspects of concerns are discussed in detail and further work in the future is recommended.

  • Valorization of waste cabbage leaves by postharvest photochemical treatments monitored with a non-destructive fluorescence-based sensor
    • Artur Kowalski
    • Giovanni Agati
    • Maria Grzegorzewska
    • Ryszard Kosson
    • Barbara Kusznierewicz
    • Tomasz Chmiel
    • Agnieszka Bartoszek-Pączkowska
    • Lorenza Tuccio
    • Daniele Grifoni
    • Ingunn M. Vagen
    • Stanislaw Kaniszewski
    2021 Pełny tekst JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY

    The biosynthesis of polyphenolic compounds in cabbage waste, outer green leaves of white head cabbage (Brassica oleracea L. var. capitata subvar. alba), was stimulated by postharvest irradiation with UVB lamps or sunlight. Both treatments boosted the content of kaempferol and quercetin glycosides, especially in the basal leaf zone, as determined by the HPLC analysis of leaf extracts and by a non-destructive optical sensor. The destructive analysis of samples irradiated by the sun for 6 days at the end of October 2015 in Skierniewice (Poland) showed an increase of leaf flavonols by 82% with respect to controls. The treatment by a broadband UVB fluorescent lamp, with irradiance of 0.38 W m−2 in the 290–315 nm range (and 0.59 W m−2 in the UVA region) for 12 h per day at 17 °C along with a white light of about 20 μmol m−2 s−1, produced a flavonols increase of 58% with respect to controls. The kinetics of flavonols accumulation in response to the photochemical treatments was monitored with the FLAV non-destructive index. The initial FLAV rate under the sun was proportional to the daily radiation doses with a better correlation for the sun global irradiance (R2 = 0.973), followed by the UVA (R2 = 0.965) and UVB (R2 = 0.899) irradiance. The sunlight turned out to be more efficient than the UVB lamp in increasing the flavonols level of waste leaves, because of a significant role played by UVA and visible solar radiation in the regulation of the flavonoid accumulation in cabbage. The FLAV index increase induced on the adaxial leaf side was accompanied by a lower but still significant FLAV increase on the unirradiated abaxial side, likely due to a systemic signaling by mean of the long-distance movement of macromolecules. Our present investigation provides useful data for the optimization of postharvest photochemical protocols of cabbage waste valorization. It can represent a novel and alternative tool of vegetable waste management for the recovery of beneficial phytochemicals.

  • Vibro piles performance prediction using result of CPT
    • Paweł Więcławski
    2021 Pełny tekst Studia Geotechnica et Mechanica

    Vibro piles belong to the group of full displacement piles with an expanded base, characterised by a very high load capacity, especially in non-cohesive soils. The problem is to adopt a reliable method for the determination of full load–settlement (Q–s) curve. A frequent difficulty is the determination of the load capacity limit based on the static load test because the course of the load–settlement curve is of a linear nature. This publication presents the empirical method. It allows direct prediction of a full axially loaded pile settlement curve based on the values of qc cone resistance obtained in cone penetration test (CPT). The advantage offered by this procedure is the accuracy of the obtained limit values in relation to the actual load-bearing capacity as compared to other methods based on soil parameters obtained in in situ testing. An additional advantage is the Q–s characteristics, which enable designing for intermediate values, allowing for the criterion of minimal or equal settlements. The shape of analytical curves was compared with static pile load test (SPLT) curves. This comparison showed large convergences between the analytical and measured curves.

  • Virulence of Clinical Candida Isolates
    • Martyna Mroczyńska
    • Anna Brillowska-Dąbrowska
    2021 Pełny tekst Pathogens

    The factors enablingCandidaspp. infections are secretion of hydrolytic enzymes, adher-ence to surfaces, biofilm formation or morphological transition, and fitness attributes. The aim of thisstudy was to investigate the correlation between known extracellular virulence factors and survivalofGalleria mellonellalarvae infected with clinicalCandida. The 25 isolates were tested and the activityof proteinases among 24/24, phospholipases among 7/22, esterases among 14/23, hemolysins among18/24, and biofilm formation ability among 18/25 isolates was confirmed. Pathogenicity investiga-tion usingG. mellonellalarvae as host model demonstrated thatC. albicansisolates andC. glabrataisolate were the most virulent andC. kruseiisolates were avirulent.C. parapsilosisvirulence wasidentified as varied,C. inconspicuawere moderately virulent, and oneC. palmioleophilaisolate was oflow virulence and the remaining isolates of this species were moderately virulent. According to ourstudy, virulence ofCandidaisolates is related to the expression of proteases, hemolysins, and esterases.

  • Visegrád countries' scientific productivity in the European context: a 10-year perspective using Web of Science and Scopus
    • Magdalena Szuflita-Żurawska
    • Beata Basińska
    2021 Pełny tekst LEARNED PUBLISHING

    Measuring the growth of research productivity is a core element of performance in the higher education sector. This paper aims to analyse the scientific productivity of the Visegrád Group countries (2010-2019) based on data from the WoS and Scopus databases as well as data from secondary sources (demographic and socio-economic factors). Quantitatively, although Poland has the highest output, this is due to its comparative size, whereas output per researcher in Poland is lower than in other V4 countries. As regards the qualitative approach, Hungary and the Czech Republic are significantly more effective in terms of scientific collaboration and receive a greater number of European Research Council grants. Thus, bibliometric data in relation to cross-country characteristic indicators (socio-economic variables including expenditure on science and having prestigious universities) are related to the positions of the V4 countries. Practical implications suggest that university management within the Visegrád Group must develop and continue strategies to strengthen international collaboration between researchers in order to accelerate change in the dissemination of scientific output at the global level. Academic scholarly publishers may benefit from publishing research on specific issues important to different regions of the world in order to expand their audience and gain new potential resources.

  • Visible-light-driven lanthanide-organic-frameworks modified TiO2 photocatalysts utilizing up-conversion effect
    • Patrycja Parnicka
    • Wojciech Lisowski
    • Tomasz Klimczuk
    • Justyna Łuczak
    • Andrzej Żak
    • Adriana Zaleska-Medynska
    2021 Pełny tekst APPLIED CATALYSIS B-ENVIRONMENTAL

    Highly efficient and quite stable composite with core-shell-like architecture reported herein, responds to the challenge of sunlight-driven photocatalysts. The Ln(ndc)/TiO2 photocatalytic system comprises active lanthanide-carboxylate coordination networks (Nd, Er, Ho, and Tm as metal ions, and 2,6-naphthalene dicar-boxylic acid as the organic linker) and inert titanium dioxide and allow to convert incompatible visible radiation into functional ultraviolet photons. The combination of the antenna-reactor photocatalyst complex with Ln(ndc) shell layers promotes light harvesting and efficient mass transfer, resulting in additional photoexcited electrons. The Nd(ndc) metal-organic framework successfully activate TiO2 via up-conversion energy transfer. The apparent quantum efficiency, determined at wavelengths corresponding to the transitions from the Nd3+ground state, equals to 2.8% and 3.2% for 525 and 583 nm, respectively. Integration of the Nd(ndc) MOF and TiO2 results in the highest efficiency of phenol degradation, affording a value of 87.5% after 60 min of visible light (λ >420 nm) exposure.

  • Voice Multilateration System
    • Robert Burczyk
    • Krzysztof Cwalina
    • Małgorzata Gajewska
    • Jarosław Magiera
    • Piotr Rajchowski
    • Jarosław Sadowski
    • Jacek Stefański
    2021 Pełny tekst SENSORS

    This paper presents an innovative method of locating airplanes, which uses only voice communication between an air traffic controller and the pilot of an aircraft. The proposed method is described in detail along with its practical implementation in the form of a technology demonstrator (proof of concept), included in the voice communication system (VCS). A complete analysis of the performance of the developed method is presented, including the results of simulation and measurement tests in real conditions. The obtained results are very optimistic and indicate that the proposed solution may constitute an alternative method of locating aircraft in emergency conditions, i.e., a backup solution in the case of failure of other positioning systems.

  • Voltage variations and their reduction in a rural low-voltage network with PV sources of energy
    • Agata Szultka
    • Seweryn Szultka
    • Stanisław Czapp
    • Ryszard Zajczyk
    2021 Pełny tekst Electronics

    Renewable sources of energy (RES), especially photovoltaic (PV) micro-sources, are very popular in many countries. This way of clean power production is applied on a wide scale in Poland as well. The Polish legal regulations and tariffs specify that every prosumer in a low-voltage network may feed this network with a power not higher than the maximum declared consumed power. In power networks with RES, the voltage level changes significantly along the power line and depends on the actually generated as well as consumed power by particular prosumers. There are cases that prosumers connected to this line cannot produce and inject the full permissible power from PV sources due to the level of a voltage higher than the technically acceptable value. In consequence, it leads to the lack of profitability of investments in installations with PV sources. In this paper, voltage variations in a real rural low-voltage network with PV micro-sources are described. The possible two general solutions of voltage levels improvement are discussed – increase in the cross-sectional area of the bare conductors in the existing overhead line as well as the replacement of the overhead line with a cable line. The recommended solution for the analyzed network, giving the best reduction of voltage variations and acceptable cost, is underlined. Such a recommendation can also be utilized in other rural networks.

  • Volumetric and torque efficiency of pumps during start-up in low ambient temperatures
    • Ryszard Jasiński
    2021

    The volumetric, torque and total efficiency of hydraulic pumps change during start-up in low ambient temperatures, as well as in thermal shock conditions, un-til they reach the set conditions. The time to reach steady-state conditions de-pends on many parameters: ambient temperature, flow rate, fluid temperature, design of hydraulic units. The author carried out tests of hydraulic pumps in the Hydraulics Laboratory of the Faculty of Mechanical Engineering of the Gdańsk University of Technology. In the research four types of pumps were investigated: several gear pumps, two axial piston pumps of different designs and one radial piston pump. It was proved, that in thermal shock conditions some malfunctions may occur, espe-cially with large temperature difference between oil and pump. Experimental research of various hydraulic pumps operating in low ambient temperatures, undertaken by the author, allows to answer the question how the volumetric and torque efficiency changes in such conditions and what parame-ters does it depend on.

  • Warstwa odcinająca z geotekstyliów w nawierzchniach drogowych. Wymagania i zasady doboru właściwości
    • Jacek Alenowicz
    2021 Pełny tekst Magazyn Autostrady

    W artykule omówiono zagadnienia związane ze stosowaniem geotekstyliów jako warstwy odcinającej w budowie nawierzchni drogowych. Podano wymagania ogólne, jakie stawia się geotekstylion w omawianym zastosowaniu. Przedstawiono klasyfikacje wykorzystywane w wybranych krajach oraz wymagania stosowane w Polsce. Zwrócono uwagę na czynniki wpływające na prawidłowy wybór geotekstyliów do wykonania warstwy odcinającej

  • Waste materials assessment for phosphorus adsorption toward sustainable application in circular economy
    • Magda Kasprzyk
    • Krzysztof Czerwionka
    • Magdalena Gajewska
    2021 Pełny tekst RESOURCES CONSERVATION AND RECYCLING

    Phosphorus is the main determinant of nutrient enrichment in the water bodies. Many resources including nutrients may be shortly exhausted, assuming current consumption. This scenario leads to growing interest in resources recovery and/or reuse, which together with sustainable energy consumption and waste reduction are the main courses of the circular economy. Usage of coagulants in wastewater treatment plants (WWTP) does not allow phosphorus to be recovered from the sludge. An alternative method with recovery potential is the application of adsorbents. Many adsorbents have been approved for P-removal, however some of them are expensive. Response to that issue may be the application of waste materials and byproducts often intended for disposal/utilization. The main objective was to assess the P-removal efficiency of the waste materials/byproducts for application in small WWTP and eco-technologies like treatment wetlands as replacement of commercial adsorbents and alternative for conventional (chemical) treatment for potential phosphorus recovery. The materials investigated were (1) an expensive man-made product, (2) a byproduct with a high content of calcium oxide, and (3) drinking water treatment residuals (DWTRs) as beds from filters used to remove iron. Research was conducted in non-flow condition with various initial concentrations. The highest efficiency was received for fine-grained byproduct (9.58 mg/g), for commercial adsorbent LMB - 9.11 mg/g. The DWTRs adsorption was oscillated around 4.5 mg/g. These results confirmed the possibility of applying waste materials and byproducts for P-removal according to the circular economy idea. Further research should include implications of waste materials application to determine P-recovery concept.

  • Wastes from Agricultural Silage Film Recycling Line as a Potential Polymer Materials
    • Jerzy Korol
    • Aleksander Hejna
    • Klaudiusz Wypiór
    • Krzysztof Mijalski
    • Ewelina Chmielnicka
    2021 Pełny tekst Polymers

    The recycling of plastics is currently one of the most significant industrial challenges. Due to the enormous amounts of plastic wastes generated by various industry branches, it is essential to look for potential methods for their utilization. In the presented work, we investigated the recycling potential of wastes originated from the agricultural films recycling line. Their structure and properties were analyzed, and they were modified with 2.5 wt % of commercially available compatibilizers. The mechanical and thermal performance of modified wastes were evaluated by tensile tests, thermogravimetric analysis, and differential scanning calorimetry. It was found that incorporation of such a small amount of modifiers may overcome the drawbacks caused by the presence of impurities. The incorporation of maleic anhydride-grafted compounds enhanced the tensile strength of wastes by 13–25%. The use of more ductile compatibilizers—ethylene-vinyl acetate and paraffin increased the elongation at break by 55–64%. The presence of compatibilizers also reduced the stiffness of materials resulting from the presence of solid particles. It was particularly emphasized for styrene-ethylene-butadiene-styrene and ethylene-vinyl acetate copolymers, which caused up to a 20% drop of Young’s modulus. Such effects may facilitate the further applications of analyzed wastes, e.g., in polymer film production. Thermal performance was only slightly affected by compatibilization. It caused a slight reduction in polyethylene melting temperatures (up to 2.8 °C) and crystallinity degree (up to 16%). For more contaminated materials, the addition of compatibilizers caused a minor reduction in the decomposition onset (up to 6 °C). At the same time, for the waste after three washing cycles, thermal stability was improved. Moreover, depending on the desired properties and application, materials do not have to go through the whole recycling line, simplifying the process, reducing energy and water consumption. The presented results indicate that it is possible to efficiently use the materials, which do not have to undergo the whole recycling process. Despite the presence of impurities, they could be applied in the manufacturing of products which do not require exceptional mechanical performance.

  • Water Behavior Near the Lipid Bilayer
    • Natalia Kruszewska
    • Krzysztof Domino
    • Piotr Weber
    2021

    In this chapter, we focus on the dynamics of water molecules situated in the vicinity of a phospholipid bilayer. Using a molecular dynamics simulation method, we studied interactions between water and the bilayer and tracked trajectories of the water molecules. Based on the hypothesis that molecules trapped inside the bilayer make different motions than the ones which are either attached to the surface or move freely in the water bulk, we divided the water molecules into three groups – the ones that exhibited subdiffusion (confined) motion, the ones that move diffusionally in the bulk and the ones that move superdiffusively due to interactions with the moving bilayer. In detail, the water behavior near the bilayer has been analyzed by mean squared displacement and entropy computed separately for the above mentioned three groups of molecules. To explain the subdiffusion motion of the water molecules, the number and the duration of hydrogen bonds created between water molecules and the bilayer have been investigated. In addition, we examined the mechanism of water molecule self-diffusion, by means of statistical tests. Our studies aim to present insight into the understanding of the lipid’s role in water self-diffusion, which can be responsible for triggering different tribological responses of the system.

  • Water-lubricated stern tube bearing - experimental and theoretical investigations of thermal effects
    • Michał Wodtke
    • Wojciech Litwin
    2021 Pełny tekst TRIBOLOGY INTERNATIONAL

    The paper presents research results of thermal phenomena accompanying operation of a water-lubricated stern tube bearing with axial grooves. Experimental tests revealed, that intensity of forced axial flow has strong influence on bush temperature. Numerical simulations focused on investigation of the thermal phenomena under operation of water-lubricated journal bearing showed, that restricted axial flow promotes backflow of the water from bearing’s side zones through the grooves. The backflow temperature is higher than the supply temperature since under the conditions of restricted forced axial flow, it is impacted mainly by the temperature of the water outflow from the gap, which is higher due to the shearing of lubricating film. This effect causes rise in the temperature of the bearing bush.

  • W-dominance: Tradeoff-inspired dominance relation for preference-based evolutionary multi-objective optimization
    • Rafał Szłapczyński
    • Joanna Szłapczyńska
    2021 Pełny tekst Swarm and Evolutionary Computation

    The paper presents a method of incorporating decision maker preferences into multi-objective meta-heuristics. It is based on tradeoffcoefficients and extends their applicability from bi-objective to multi-objective. The method assumes that a decision maker specifies a priori each objective’s importance as a weight interval. Based on this, w-dominance relation is introduced, which extends Pareto dominance. By replacing reference points with weight intervals the method eliminates the need for any knowledge concerning expected solutions. Instead, decision maker reflects his context-independent policy regarding objectives. The proposed w-dominance was incorpo- rated into selected multi-objective metaheuristics. Following this, three new metrics were designed. The metrics include prescreening true Pareto Front and final population according to w-dominance relation. Based on pre- liminary tests, Vector Angle Evolutionary Algorithm (VaEA) was selected as the best match for w-dominance. W-dominance-extended VAEA (wVAEA) was compared in a series of simulations with four state-of-the-art refer- ence point-based multi-objective algorithms. The results show that wVaEA outperforms the four representative algorithms for selected benchmark problems.

  • Weakly-Supervised Word-Level Pronunciation Error Detection in Non-Native English Speech
    • Daniel Korzekwa
    • Jaime Lorenzo-trueba
    • Thomas Drugman
    • Shira Calamaro
    • Bożena Kostek
    2021 Pełny tekst

    We propose a weakly-supervised model for word-level mispronunciation detection in non-native (L2) English speech. To train this model, phonetically transcribed L2 speech is not required and we only need to mark mispronounced words. The lack of phonetic transcriptions for L2 speech means that the model has to learn only from a weak signal of word-level mispronunciations. Because of that and due to the limited amount of mispronounced L2 speech, the model is more likely to overfit. To limit this risk, we train it in a multi-task setup. In the first task, we estimate the probabilities of word-level mispronunciation. For the second task, we use a phoneme recognizer trained on phonetically transcribed L1 speech that is easily accessible and can be automatically annotated. Compared to state-of-the-art approaches, we improve the accuracy of detecting word-level pronunciation errors in AUC metric by 30% on the GUT Isle Corpus of L2 Polish speakers, and by 21.5% on the Isle Corpus of L2 German and Italian speakers

  • Weldability of Underwater Wet-Welded HSLA Steel: Effects of Electrode Hydrophobic Coatings
    • Jacek Tomków
    2021 Pełny tekst Materials

    The paper presents the effects of waterproof coatings use to cover electrodes on the weldability of high-strength, low-alloy (HSLA) steel in water. With the aim of improving the weldability of S460N HSLA steel in water, modifications of welding filler material were chosen. The surfaces of electrodes were covered by different hydrophobic substances. The aim of the controlled thermal severity (CTS) test was to check the influence of these substances on the HSLA steel weldability in the wet welding conditions. The visual test, metallographic tests, and hardness Vickers HV10 measurements were performed during investigations. The results proved that hydrophobic coatings can reduce the hardness of welded joints in the heat-affected zone by 40–50 HV10. Additionally, the number of cold cracks can be significantly reduced by application of waterproof coatings on the filler material. The obtained results showed that electrode hydrophobic coatings can be used to improve the weldability of HSLA steel in underwater conditions.

  • What do hashtags afford in digital fashion communication? An exploratory study on Gucci-related hashtags on Twitter and Instagram.
    • Olga Karamalak
    • Nadzeya Kalbaska
    • Lorenzo Cantoni
    2021 Semiotica : Journal of the International Association for Semiotic Studies

    Being enmeshed in a digital environment, we daily produce internet-mediated texts – encompassing several different semiotic codes – accessible on a global scale. Posts on different networks usually contain hashtags, which can be understood as affordances or behavior opportunities. These affordances allow specific actions both from the part of the writer and the reader. They can also be “behavior triggers,” which invite certain behavior online (e.g., to like, share, comment) or offline (e.g., to buy items of a specific brand). Digital fashion communication experts should take into consideration these affordances to pursue their goals in the activities related to marketing, promoting, creating engagement and communicating either about a brand or a brand item. While there is general research on reasons to hashtag and on the functions they perform, there is a gap in what hashtags “mean” and “do” in the fashion domain. The objectives of this paper are threefold: 1) to give an overview of the history of hashtags; 2) to present the affordances of hashtags, while creating a general table of affordances from the addresser’s perspective, based on the literature overview; 3) to perform a qualitative analysis of hashtags on Gucci official Twitter and Instagram accounts during a given time span and on other Gucci-related hashtags posted by common users. The choice of the brand is due to Gucci’s focus on active digital communication practices. Results can be valuable for both researchers and industry professionals involved in digital fashion communication.

  • What matters most to patients? On the Core Determinants of Patient Experience from Free Text Feedback
    • Adegboyega Ojo
    • Nina Rizun
    2021 Pełny tekst

    Free-text feedback from patients is increasingly used for improving the quality of healthcare services and systems. A major reason for the growing interest in harnessing free-text feedback is the belief that it provides richer information about what patients want and care about. The use of computational approaches such as structural topic modelling for analysing large unstructured textual data such as free-text feedback from patients has also been gain traction lately. However, its use for generating insights is constrained by the apparent lack of statistical rigour and explanatory capability required for credible evidence in decision making. From the theoretical perspective, theory-building from unstructured textual data is also currently problematic in IS and health service research. This study presents an approach to address this challenge by integrating text analytics, predictive and quantitative models as part of a computational grounded theory approach to determine factors that significantly determine overall patient experience.

  • Where Did Knowledge Management Go?: A Comprehensive Survey
    • Rodrigo Oliveira de Castro
    • Cesar Sanin
    • Edward Szczerbicki
    • Andrew Levula
    2021 Pełny tekst CYBERNETICS AND SYSTEMS

    Knowledge Management (KM) research outputs have been expanding exponentially in the past years, generating diversified topics, which lack integration and classification. It has been challenging for experts to classify KM because of its versatile open fields, and in our view, it contributes to the technocratic approach remaining behind the organizational approach. This paper highlights a way to classify KM publications through a pattern that will support technocratic developments representing knowledge in a more explicit form. This study uses a classification method thatuses a template in a taxonomy shape, executing some procedures and allowingan accurate identification and organizationof KM research outputs. The proposed taxonomy method is proven on a set of 150 different KM publications from the last 15 years. This scheme is grouped into two main categories: Conceptual and Empirical which could enable academics and practitioners alike to better understand the current gaps that are prevalent in KM.

  • Wideband Modeling of DC-DC Buck Converter with GaN Transistors
    • Piotr Musznicki
    • Pawel B. Derkacz
    • Piotr Chrzan
    2021 Pełny tekst ENERGIES

    The general wideband modeling method of the power converter is presented on the example of DC-DC buck converter with GaN High Electron Mobility Transistors (HEMT). The models of all basic and parasitic components are briefly described. The two methods of Printed Circuit Board (PCB) layout parameter extraction are presented. The results of simulation in Saber@Sketch simulation software and measurements are compared. Next, the model of the converter is reduced to obtain one lumped inductance of the input filter PCB for the analytical prediction of transistor turn-off ringing frequency and overvoltage. The practical use of the model is presented for sizing optimal capacitance of snubber.

  • Wind Conditions at Pedestrian Level in Different Types of Residential Urban Development for a High Degree of Land Use Efficiency
    • Katarzyna Zielonko-Jung
    • Marta Poćwierz
    • Robert Idem
    2021 Pełny tekst Sustainability

    The paper concerns wind conditions around urban building development at the pedestrian level. The article aims to identify aerodynamic phenomena around three types of multi-family housing developmentswith different forms and the same urban parameters of building development intensity (high intensity was taken into account). The aim of the research was mainly to achieve qualitative results that would lead to understanding fundamental processes and phenomena. Experimental studies in the wind tunnel were conductedon physical models at a scale of 1: 400 using visualization and erosion methods. These experiments yielded data regarding the arrangement of airflow directions and changes in airflow velocity, expressed as the amplification coefficient (α), the occurrence of which was caused by the presence of buildings. An analysis was conducted concerning wind conditions that constitute pedestrian comfort and influence the possibility for ventilation of spaces between buildings for the three selected models. The research results were compared, and an attempt was made to assess the most beneficial and the least favorable building development typesseem in this respect.

  • Wisdom from Experience Paradox: Organizational Learning, Mistakes, Hierarchy and Maturity Issues
    • Wioleta Kucharska
    2021 Pełny tekst Electronic Journal of Knowledge Management

    Organizations often perceive mistakes as negligence and low-performance indicators, yet they can be a precious learning resource. However, organizations cannot learn from mistakes if they have not accepted them. This study aimed to explore how organizational hierarchy and maturity levels influence the relationship between mistakes acceptance and the ability to change. A sample composed of 380 Polish employees working in knowledge-driven organizations across various industries examined this phenomenon. Data collection occurred from November to December 2019. Data were analyzed through OLS regression, using PROCESS software. The findings revealed that the acceptance of mistakes positively influences adaptability to change. Moreover, because of mistakes acceptance, knowledge workers in organizations with a low-level hierarchy adapt to changes more effectively than those who work in strongly (or high-level) hierarchical companies. Additionally, higher hierarchy levels result in lower adaptability to change, which is particularly visible in mature organizations. The study's essence is the empirical proof that a high level of organizational maturity and hierarchy can block the adaptability to change if the organization stays on the single-loop of learning (does perfectly what it used to do). Mistakes acceptance and thanks to this, also learning from mistakes, support organizational change adaptability. Change adaptability is vital for double-loop learning (organizational actions re-framing). Moreover, this study has exposed the paradox of ‘wisdom from experience’ empirically. Namely, it is expected that experience and maturity result in positive outcomes and increased organizational leverage. Whereas more prominent, experienced, and mature organizations face serious difficulties when changing their routines and behaviors.