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Gdańsk University of Technology

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  • Cross-Linking, Morphology, and Physico-Mechanical Properties of GTR/SBS Blends: Dicumyl Peroxide vs. Sulfur System
    • Agata Rodak
    • Agnieszka Susik
    • Daria Kowalkowska-Zedler
    • Łukasz Zedler
    • Krzysztof Formela
    2023 Full text Materials

    In this work, ground tire rubber and styrene–butadiene block copolymer (GTR/SBS) blends at the ratio of 50/50 wt%, with the application of four different SBS copolymer grades (linear and radial) and two types of cross-linking agent (a sulfur-based system and dicumyl peroxide), were prepared by melt compounding. The rheological and cross-linking behavior, physico-mechanical parameters (i.e., tensile properties, abrasion resistance, hardness, swelling degree, and density), thermal stability, and morphology of the prepared materials were characterized. The results showed that the selected SBS copolymers improved the processability of the GTR/SBS blends without any noticeable effects on their cross-linking behavior—which, in turn, was influenced by the type of cross-linking agent used. On the other hand, it was observed that the tensile strength, elongation at break, and abrasion resistance of the GTR/SBS blends cured with the sulfur system (6.1–8.4 MPa, 184–283%, and 235–303 mm3, respectively) were better than those cross-linked by dicumyl peroxide (4.0–7.8 MPa, 80–165%, and 351–414 mm3, respectively). Furthermore, it was found that the SBS copolymers improved the thermal stability of GTR, while the increasing viscosity of the used SBS copolymer also enhanced the interfacial adhesion between the GTR and SBS copolymers, as confirmed by microstructure evaluation.

  • Crystal facet effects in photocatalytic degradation of organic pollutants over anatase TiO2
    • Szymon Dudziak
    2023 Full text

    Presented work show detailed effect of the exposed crystal facets of anatase TiO2 on the photocatalytic degradation of organic pollutants. The most important existing information about the geometry and electronic properties of the low index anatase facets are summarised. During the performed works, anatase nanoparticles with the dominant exposition of either {0 0 1}, {1 0 0} or {1 0 1} crystal facets were prepared and their photocatalytic activity was tested. A significant effect of the exposed crystal facets was observed for the degradation and mineralisation of compounds, such as phenol, toluene, ibuprofen, carbamazepine and acetaminophen. Overall results have indicated significant effect of the exposed facet, with stoichiometric {1 0 1} being the most suitable for both degradation and mineralisation of all studied compounds, with the observed degradation rate constant being approximately 2-3 higher than other nanostructures. Furthermore, after combining with the BaFe12O19 ferrite, different effects of both electronic and magnetic interactions between both phases were observed, depending on the exposed TiO2 facets. Finally, doping of the obtained structures allowed to maximise activity of the {1 0 1} facets, simultaneously showing different effect of the same dopant, depending on the surface electronic structure of the material.

  • Crystal Facet Engineering of TiO2 from Theory to Application
    • Szymon Dudziak
    • Marta Kowalkińska
    • Anna Zielińska-Jurek
    2023 Full text

    Recently, the surface structure effect on photocatalytic activity has gathered increasing attention due to its reported influence on the charge carrier trapping and separation. Detailed control over the surface structure can be achieved by exposing the specific crystal facets. As a result, the photogenerated electrons and holes can be effectively separated between the different facets of semiconductor crystals. TiO2 is the most studied photocatalyst, with the particles exposing {0 0 1}, {1 0 0}, {1 0 1}, {1 1 0}, {1 1 1}, and {1 0 5} crystal facets. The performed studies have shown that the efficiency of the photocatalytic process strongly depends on the nature of the crystal facet exposed at the photocatalyst surface. In this regard, this chapter focuses on the comparison of possible surface-related parameters and photocatalytic activity of anatase, rutile, and brookite polymorphs with exposed different crystal facets. Particularly, computational data on their different possible surface structures are summarized, focusing on the geometry, energy, and possible reconstructions. This is followed by the general description of the hypothetical Wulff constructions and existing stabilization/synthesis strategies. Such an approach could help to further design, simulate, and optimize photocatalyst surface for efficient photoreduction and photooxidation processes.

  • Crystalline Silicon (c-Si)-Based Tunnel Oxide Passivated Contact (TOPCon) Solar Cells: A Review
    • Hayat Ullah
    • Stanisław Czapp
    • Seweryn Szultka
    • Hanan Tariq
    • Usama Bin Qasim
    • Hassan Imran
    2023 Full text ENERGIES

    Contact selectivity is a key parameter for enhancing and improving the power conversion efficiency (PCE) of crystalline silicon (c-Si)-based solar cells. Carrier selective contacts (CSC) are the key technology which has the potential to achieve a higher PCE for c-Si-based solar cells closer to their theoretical efficiency limit. A recent and state-of-the-art approach in this domain is the tunnel oxide passivated contact (TOPCon) approach, which is completely different from the existing classical heterojunction solar cells. The main and core element of this contact is the tunnel oxide, and its main role is to cut back the minority carrier recombination at the interface. A state-of-the-art n-type c-Si-based TOPCon solar cell featuring a passivated rear contact was experimentally analyzed, and the highest PCE record of ~25.7% was achieved. It has a high fill factor (FF) of ~83.3%. These reported results prove that the highest efficiency potential is that of the passivated full area rear contact structures and it is more efficient than that of the partial rear contact (PRC) structures. In this paper, a review is presented which considers the key characteristics of TOPCon solar cells, i.e., minority carrier recombination, contact resistance, and surface passivation. Additionally, practical challenges and key issues related to TOPCon solar cells are also highlighted. Finally, the focus turns to the characteristics of TOPCon solar cells, which offer an improved and better understanding of doping layers and tunnel oxide along with their mutual and combined effect on the overall performance of TOPCon solar cells.

  • Cu( II ) ions removal from wastewater using starch nanoparticles ( SNPs ): An Eco‐sustainable approach
    • Vikas S. Hakke
    • Vividha K. Landge
    • Shirish H. Sonawane
    • G. Uday B. Babu
    • Sivakumar Manickam
    • Grzegorz Boczkaj
    2023 Full text CANADIAN JOURNAL OF CHEMICAL ENGINEERING

    The complex structured starch particles were reduced to the nanoscale size range through hydrolysis utilizing low concentration acid assisted with ultrasound irradiation. The synthesized starch nanoparticles (SNPs) were characterized by TEM, FTIR, and XRD techniques. The synthesized SNPs possessed surface activated entities, as many cationic functional groups were confirmed through the FTIR spectrum. Also, these SNPs were effectively utilized to separate heavy Cu metal ions from the synthetic ion solution. The SNPs were characterized using FESEM, XPS and BET for the surface modification after the adsorption process. The weak electrostatic interaction between the SNP surface and Cu ion was confirmed from the XPS spectrum and energy dispersive X-ray spectroscopy. The maximum efficiency of Cu ions removal was about 93% at an optimal pH 5 and 25 mg/mL dosage. The adsorption equilibrium was obtained in 60 min. The nitrogen isotherm BET analysis of SNPs after adsorption shows a higher specific surface area of 18.552 m2/g, attributed to the interaction and presence of Cu ions on the SNP surface. The process feasibility was validated by the Langmuir isotherm model. The process exhibits pseudo-second-order adsorption kinetics and follows the Langmuir isotherm. The RL predicted by the Langmuir isotherm mechanism is 0.017, implying favorable adsorption. The process is reproducible and allows to separate heavy metal ions from the wastewater through bio-sorption effectively.

  • Cu-HKUST-1 and Hydroxyapatite–The Interface of Two Worlds toward the Design of Functional Materials Dedicated to Bone Tissue Regeneration
    • Marzena Fandzloch
    • Weronika Bodylska
    • Joanna Trzcińska-Wencel
    • Patrycja Golińska
    • Katarzyna Roszek
    • Joanna Wiśniewska
    • Michał Bartmański
    • Agnieszka Lewińska
    • Anna Jaromin
    2023 Full text ACS Biomaterials Science & Engineering

    A novel composite based on biocompatible hydroxyapatite (HA) nanoparticles and Cu-HKUST-1 (Cu-HKUST-1@HA) has been prepared following a layer-by-layer strategy. Cu-HKUST-1 was carefully selected from a group of four Cu-based metal−organic frameworks as the material with the most promising antimicrobial activity. The formation of a colloidal Cu- HKUST-1 layer on HA nanoparticles was confirmed by various techniques, e.g., infrared spectroscopy, powder X-ray diffraction, N2 sorption, transmission electron microscopy imaging, electron paramagnetic resonance, and X-ray absorption spectroscopy. Importantly, such a Cu-HKUST-1 layer significantly improved the nanomechanical properties of the composite, with Young’s modulus equal to that of human cortical bone (13.76 GPa). At the same time, Cu-HKUST-1@HA has maintained the negative zeta potential (−16.3 mV in pH 7.4) and revealed biocompatibility toward human dermal fibroblasts up to a concentration of 1000 μg/mL, without inducing ex vivo hemolysis. Chemical stability studies of the composite over 21 days in a buffer-simulated physiological fluid allowed a detailed understanding of the transformations that the Cu-HKUST-1@HA undergoes over time. Finally, it has been confirmed that the Cu-HKUST-1 layer provides antibacterial properties to HA, and the synergism reached in this way makes it promising for bone tissue regeneration.

  • CuO-decorated MOF derived ZnO polyhedral nanostructures for exceptional H2S gas detection
    • Shahid Hussain
    • Jesse Nii Okai Amu-Darko
    • Mingsong Wang
    • Asma A. Alothman
    • Mohamed Ouladsmane
    • Samar A. Aldossari
    • Muhammad Khan
    • Guanjun Qiao
    • Guiwu Liu
    2023 CHEMOSPHERE

    Considering that H2S is a hazardous gas that poses a significant risk to people's lives, research into H2S gas sensors has garnered a lot of interest. This work reports a CuO/ZnO multifaceted nanostructures(NS) created by heat treating Cu2+/ZIF-8 impregnation precursors, and their microstructure and gas sensing characteristics were examined using various characterization techniques (XRD, XPS, SEM, TEM, and BET). The as-prepared hollow CuO/ZnO multifunctional nanostructures had a high gas response value (425@50 ppm H2S gas), quick response and recovery times (57/191s @20 ppm), a low limit of detection ( 1.6@500 ppb H2S), good humidity resistance and highly selective towards H2S gas. The hollow CuO/ZnO multifaceted nanostructures possessed enhanced gas sensing capabilities which may be related to their porous hollow nanostructures, the manufactured p-CuO/n-ZnO heterojunctions, and the spillover effect between CuO and H2S.

  • Cyclic behavior of FeCoCrNiMn high entropy alloy coatings produced through cold spray
    • Pasquale Cavaliere
    • Angelo Perrone
    • Alessio Silvello
    • Aleksandra Laska
    • Gianni Blasi
    • Irene G. Cano
    • Behzad Sadeghi
    • S. Nagy
    2023 JOURNAL OF ALLOYS AND COMPOUNDS

    eCoCrNiMn high entropy alloy powders were employed to produce coatings on carbon steel through high pressure cold spray (at 1100 °C and 7 MPa in temperature and pressure respectively). X-ray diffraction of the sprayed material revealed a dense coating with the retention of the original crystallographic structure. Once splatted, particles revealed high flattening ratio with consequent excellent adhesion of the coating to the substrate. Residual stresses and hardness increased through the thickness of the coating. The cyclic behavior of the coatings was evaluated through bending tests. The cyclic bending tests were performed by linearly increase the maximum deformation at a fixed number of loading cycles. Other bending tests were conducted at fixed maximum stroke at the same deformation levels indicated for the previous test up to the coating fracture. For ach 100 cycles the test was stopped in order to observe the coating surface to gain the possibility of evaluating the aspect of the superficial fracture. The fracture surface of the coatings was observed through scanning electron microscopy in order to describe the cracking features related to the different loading conditions imposed to the coatings.

  • Cyfrowy HR. Organizacja w warunkach transformacji technologicznej
    • Małgorzata Sidor-Rządkowska
    • Łukasz Sienkiewicz
    2023

    Publikacja jest pierwszą na rynku pozycją opisującą kompleksowo zagadnienia związane z cyfryzacją HR. Autorzy szczegółowo omawiają poszczególne aspekty procesu wdrażania rozwiązań cyfrowych, a także podkreślają kluczową rolę, jaką dział HR odgrywa w kształtowaniu nowej cyfrowej kultury organizacyjnej w firmie. W monografii omówiono zagadnienia takie jak m.in.: * nowe role HR w procesie digitalizacji firmy, * cyfrowe zarządzanie danymi personalnymi, * analityka predykcyjna i algorytmy w HR, * wpływ kluczowych technologii na zmiany w obszarze pracy. Autorzy poruszają także etyczny aspekt transformacji cyfrowej, wskazując przykładowe dylematy związane z ochroną i wykorzystaniem danych osobowych, przejrzystością procesów czy dobrostanem pracowników.

  • Cykl obrazów: CZŁOWIEK WOBEC| uwspólnienie udział w ogólnopolskiej wystawie zbiorowej EMOTIONAL ECOLOGY / EKOLOGIA EMOCJONALNA. Ekologia, humanizm, etyka. Świadomość historii wzornictwa i nowe ścieżki rozwojowe jako element procesu. | cykl: ‘Design w procesie’
    • Agnieszka Kurkowska
    2023

    „Zależności pomiędzy organizmami i miejscem ich przebywania, są obszarem zainteresowania kreatorek i kreatorów. Czerpią oni impuls płynący z emocji własnych i innych organizmów. W efekcie synergii emocji, powstaje perspektywa przestrzeni naturalnej. Ekologia opiera się na systemie wymiany pomiędzy miejscem przebywania a kreatorami. Relacja ta zachodzi dokładnie pomiędzy jednostką a środowiskiem społecznym i naturalnym. Człowiek współstanowi o niesamowitej relacji emocjonalnej, powstającej w pewnym splocie istnienia organizmu ludzkiego i jego otoczenia. W ten sposób kreuje się wielo-organizm. Jego funkcje, sposoby zachowania, uwarunkowania kulturowe wynikają bezpośrednio z natury, z szacunku do otaczającego świata. Nowy sposób wymiany pomiędzy człowiekiem a środowiskiem proponują twórcy kierujący się tropem emocji. Stąd nie jesteśmy ludźmi sami przez się, ale poprzez istnienie (proces życiowy) w środowisku zewnętrznym, organizowanym przez emocje.

  • Cykl rzeźb pt. 'struktury biomorficzne'
    • Agnieszka Kurkowska
    2023

    Dotykam świata formą. Tworzę ją z marzeń i obrazów przyrody. Jestem architektem, co pozwala mi dotykać wzrokiem. Rysuję, rzeźbię, sytuuję gliniane obiekty i sprawdzam, czy miejsce je akceptuje. Poszukuję odczucia zgodności. Zgodność kierunkuje podejmowane próby. Wyobraźnia pyta o mieszkańców. Formy mogą mieścić domy. Schronienia bezpiecznie osadzone w kaszubskim krajobrazie. Brzmiące lasem, pachnące tradycją. Nie znam ich dalszych losów. Zawieszam myśli pomiędzy tym co wiem, a tym czego się spodziewam. Moje doświadczenia tworzą kształty. Spokój miejsca daje siłę do pracy. Utkane z marzeń, ułożone z doświadczeń, dotykające z nadzieją, formą zapożyczoną, przemyślaną i podarowaną miejscu. Najważniejsze jest dotknięcie, rozciągłe po nieregularności obiektu. Dotknięcie podłoża i powietrza. Tła. Uwolniony zapach i przeczucie. Ulotność, która nadaje sens. „Dotykanie jest zjawiskiem dwustronnym. To świat nas dotyka, gdy my go dotykamy” * Zarys i płaszczyzna styku. Definiują przebieg relacji. Oczekuję od nich potwierdzenia celu poszukiwań. Ten etap procesu niesie obawy niepowodzeń, ale i nadzieję adaptacji. Kto powiedział, że architekt nie może w ten sposób poszukiwać formuły dla domu spasowanego z miejscem? Mniej dosłownie. Bardziej delikatnie. Przyglądając się nieuchwytności i ciesząc słońcem dotykającym gliny z odciskiem mojej skóry. „Dzięki dotykowi nasza obecność objawia się nie w przestrzeni, tylko wobec innej, bliskiej rzeczywistości” * *cytaty: Brach-Czaina Jolanta 2022. Błony umysłu. Dowody na istnienie, Warszawa

  • Cylindrical orifice testing in laminar flow with the orifice diameter ratio β = 0.5
    • Anna Golijanek-Jędrzejczyk
    • Andrzej Mrowiec
    2023 Full text Scientific Reports

    The paper presents the results of an experimental study of a cylindrical orifice with the orifice diameter ratio β = 0.5 and the flow opening length‑to‑diameter ratio L/d = 1, with hydraulic oil flowing in the DN50 measuring channel. The measurements of the values characterising the oil flow were made in the laminar flow regime, for the Reynolds numbers ranging between Re = 100 to 950. Based on the experimental tests, standard flow characteristics were created for four kinematic viscosity values in the range of 13.4–33.3 cSt, for which the average value of the discharge coefficient C in the tested flow rate range of q v < 0.5 dm 3 /s was determined.

  • Cytokine IL6, but not IL-1β, TNF-α and NF-κB is increased in paediatric cancer patients
    • Anna Synakiewicz
    • Anna Stanisławska-Sachadyn
    • Anna Owczarzak
    • Małgorzata Skuza
    • Teresa Stachowicz-Stencel
    2023 Full text Acta Biochimica Polonica

    Cytokines are responsible for maintaining homeostasis as cell growth, differentiation, migration and apoptosis mediators. They play a pivotal role in immune responses to inflammatory reactions. In oncological diseases, the cross-talk between cells of the immunological system and cells of the tumour microenvironment is led by cytokines. Also, the overproduction of cytokines may change the tumour microenvironment and stimulate tumour development and growth. To test whether pro-inflammatory cytokines or associated with them transcription factor levels are changed in a group of 53 paediatric cancer patients, serum levels of IL-1β, IL-6, TNF-α and NF-κB were assessed and compared to measures in 25 healthy controls. Increased levels of IL-6 were found among patients in active oncological treatment (P=0.002) but not among patients whose treatment was completed. Our data suggest that IL6, but not IL-1β, TNF-α and NF-κB, is elevated as a result of the immune response in the microenvironment around the tumour and in blood cancers, among patients who were not infected at the time of blood collection. Thus, IL6 levels might serve as a potential biomarker of oncohematological diseases.

  • Czy chemia wszechświata różni się od chemii na planecie Ziemia?
    • Bartłomiej Cieślik
    2023

    Astronomowie, fizycy i chemicy od lat zadają sobie pytanie na ile nasza planeta jest wyjątkowa. Żyjemy na jednym z nielicznych ciał niebieskich, na którym występuje woda w stanie ciekłym. Na naszej planecie pojawiła się niezwykle szeroka gama prostych i wyjątkowo skomplikowanych związków organicznych. Warto jednak zadać pytanie czy faktycznie ziemia jest tak wyjątkowa pod kątem chemicznym, a jeśli tak to co na to wpływa. Współcześnie naukowcy wiedzą już o wszechświecie na tyle dużo, że można spróbować odpowiedź na to pytanie.

  • Czynniki kształtujące skuteczność outsourcingu w podmiotach leczniczych
    • Piotr Grudowski
    • Mateusz Muchlado
    2023

    Problem badawczy podjęty przez autorów tej książki można więc sformułować następująco: Jakie procesy podlegają outsourcingowi i jakie czynniki decydują o ich skuteczności w szpitalach w Polsce? W konsekwencji celem badawczym przyjętym w niniejszej pracy jest identyfikacja procesów zlecanych na zewnątrz w polskich szpitalach wraz z czynnikami warunkującymi ich skuteczność. Celem utylitarnym jest zaś opracowanie metody umożliwiającej kadrze zarządzającej polskimi szpitalami dobór dostawców oraz ocenę procesów poddanych outsourcingowi. Niniejsza monografia składa się z trzech głównych rozdziałów. W rozdziale 1 omówiono pojęcie outsourcingu oraz wykorzystanie go w zarządzaniu procesami. Opisano też czynniki sprawiające, że organizacje decydują się na zlecanie procesów na zewnątrz, jak również szanse i zagrożenia z tym związane. Przedstawiono charakterystykę podejścia procesowego, a także metody klasyfikacji procesów, których zastosowanie jest niezbędne przy wydzielaniu procesu na zewnątrz. Scharakteryzowano też najczęściej wykorzystywane w praktyce oraz sugerowane w literaturze przedmiotu metody oceny skuteczności procesów. W rozdziale 2 przedstawiono organizacje stanowiące podmiot badań oraz ich charakterystykę w świetle literatury. Zawarto tu również wnioski płynące z przeglądu literatury dotyczącej outsourcingu w podmiotach leczniczych w Polsce i za granicą, które odnoszą się do rodzaju procesów wydzielanych oraz motywów prowadzących do outsourcingu. Opisano uwarunkowania prawne i normatywne wpływające na wybór dostawcy outsourcingowego i ocenę skuteczności procesów poddanych outsourcingowi. W rozdziale 3 przedstawiono zastosowaną przez autorów metodykę badawczą. Zaprezentowano wybrane wyniki badań, które posłużyły do weryfikacji postawionych hipotez, a także do osiągnięcia celu utylitarnego, czyli opracowania metody oceny skuteczności procesów poddanych outsourcingowi. Metoda ta została omówiona w końcowej. części rozdziału. W podsumowaniu przedstawiono ujęte syntetycznie wyniki przeprowadzonych badań, wnioski i rekomendacje, w tym te związane z funkcjonowaniem placówek ochrony zdrowia w warunkach kryzysu i niepewności. Książka adresowana jest przede wszystkim do osób zajmujących się zarządzaniem w sektorze ochrony zdrowia, zarówno praktyków, jak i badaczy tej problematyki. Powinna się też spotkać z zainteresowaniem studentów kierunków związanych z zarządzaniem w usługach publicznych.

  • Data, Information, Knowledge, Wisdom Pyramid Concept Revisited in the Context of Deep Learning
    • Bożena Kostek
    2023

    In this paper, the data, information, knowledge, and wisdom (DIKW) pyramid is revisited in the context of deep learning applied to machine learningbased audio signal processing. A discussion on the DIKW schema is carried out, resulting in a proposal that may supplement the original concept. Parallels between DIWK pertaining to audio processing are presented based on examples of the case studies performed by the author and her collaborators. The studies shown refer to the challenge concerning the notion that classification performed by machine learning (ML) is/or should be better than human-based expertise. Conclusions are also delivered.

  • Data-driven, probabilistic model for attainable speed for ships approaching Gdańsk harbour
    • Jakub Montewka
    • Marcin Życzkowski
    • Filip Zarzycki
    2023

    The growing demand for maritime transportation leads to increased traffic in ports. From this arises the need to observe the consequences of the specific speed ships reach when approaching seaports. However, usually the analyzed cases refer only to the statistical evaluation of the studied phenomenon or to the empirical modelling, ignoring the mutual influence of variables such as ship type, length or weather conditions. In this paper, a different approach to the issue is proposed, which summarizes the most important factors and leads to a probabilistic speed model for manoeuvring ships in the port of Gdańsk. For this purpose, data from the Automatic Identification System were used. This resulted in a dataset with almost 2.5k traffic scenarios. To obtain results from the dataset, three different machine learning algorithms based on Bayesian networks were then applied. The developed models can be used to predict the speed as a function of the given parameters as well as to determine the values of individual parameters for a given speed. In addition, the use of the constructed models allowed the analysis of the strength of mutual influences for two connected nodes or the sensitivity of changes for individual variables. The discussion also raised questions about validation of the algorithms and measures to improve accuracy. The average predictive accuracy of the models of about 75% (depending on the learning algorithm used) achieved at this stage is promising, but further work is expected that can increase the predictive power of the models.

  • Data-Driven Surrogate-Assisted Optimization of Metamaterial-Based Filtenna Using Deep Learning
    • Peyman Mahouti
    • Aysu Belen
    • Ozlem Tari
    • Mehmet Belen
    • Serdal Karahan
    • Sławomir Kozieł
    2023 Full text Electronics

    In this work, a computationally efficient method based on data driven surrogate models is pro-posed for the design optimization procedure of a Frequency Selective Surface (FSS)-based filtering antenna (Filtenna). A Filtenna acts as a as module that simultaneously pre-filters unwanted sig-nals, and enhances the desired signals at the operating frequency. However, due to a typically large number of design variables of FSS unit elements, and their complex interrelations affecting the scattering response, FSS optimization is a challenging task. Herein, a deep-learning-based al-gorithm, Modified-Multi-Layer-Perceptron (M2LP), is developed to render an accurate behavioral model of the unit cell. Subsequently, the M2LP model is applied to optimize FSS elements being parts of the Filtenna under design. The exemplary device operates at 5 GHz to 7 GHz band. The numerical results demonstrate that the presented approach allows for almost 90% reduction of the computational cost of the optimization process as compared to direct EM-driven design. At the same time, physical measurements of the fabricated Filtenna prototype corroborate the relevance of the proposed methodology. One of the important advantages of our technique is that the unit cell model can be re-used to design FSS and Filtenna operating a various operating bands without incurring any extra computational expenses.

  • Dataset Related Experimental Investigation of Chess Position Evaluation Using a Deep Neural Network
    • Dawid Wieczerzak
    • Paweł Czarnul
    2023 Full text

    The idea of training Articial Neural Networks to evaluate chess positions has been widely explored in the last ten years. In this paper we investigated dataset impact on chess position evaluation. We created two datasets with over 1.6 million unique chess positions each. In one of those we also included randomly generated positions resulting from consideration of potentially unpredictable chess moves. Each position was evaluated by the Stockfish engine. Afterwards, we created a multi class evaluation model using Multilayer Perceptron. Solution to the evaluation problem was tested with three different data labeling methods and three different board representations. We show that the accuracy for the model trained for the dataset without randomly generated positions is higher than for the model with such positions, for all data representations and 3, 5 and 11 evaluation classes.

  • Debonding of coin-shaped osseointegrated implants: Coupling of experimental and numerical approaches
    • Yoann Hériveaux
    • Sophie Le Cann
    • Katharina Immel
    • Elsa Vennat
    • Vu-Hieu Nguyen
    • Vladimir Brailovski
    • Patrick Karasinski
    • Roger Sauer
    • Guillaume Haiat
    2023 Journal of the Mechanical Behavior of Biomedical Materials

    While cementless implants are now widely used clinically, implant debonding still occur and is difficult to anticipate. Assessing the biomechanical strength of the bone–implant interface can help improving the understanding of osseointegration phenomena and thus preventing surgical failures. A dedicated and standardized implant model was considered. The samples were tested using a mode III cleavage device to assess the mechanical strength of the bone-implant interface by combining experimental and numerical approaches. Four rough (Sa = 24.5 μm) osseointegrated coin-shaped implants were left in sheep cortical bone during 15 weeks of healing time. Each sample was experimentally rotated at 0.03◦/sec until complete rupture of the interface. The maximum values of the torque were comprised between 0.48 and 0.72 Nm, while a significant increase of the normal force from 7-12 N to 31–43 N was observed during the bone-implant interface debonding, suggesting the generation of bone debris at the bone-implant interface. The experimental results were compared to an isogeometric finite element model describing the adhesion and debonding phenomena through a modified Coulomb’s law, based on a varying friction coefficient to represent the transition from an unbroken to a broken bone-implant interface. A good agreement was found between numerical and experimental torques, with numerical friction coefficients decreasing from 8.93 to 1.23 during the bone-implant interface rupture, which constitutes a validation of this model to simulate the debonding of an osseointegrated bone-implant interface subjected to torsion.

  • Decomposition of the induced magnetism degaussing problem for fast determination of currents in demagnetization coils wrapped outside an object under arbitrary external field conditions
    • Mirosław Wołoszyn
    • Jarosław Tarnawski
    • Joanna Wołoszyn
    2023 Full text JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

    Safe passage of ships in the presence of sea mines can be ensured by limiting or reducing the ship’s magnetic footprint. For vessels with plastic hulls, the main component that requires magnetic damping is the engine. Demagnetization of such an object can be achieved by wrapping it with coils and setting the direct current appropriately. For each specific geographic location, the currents in the coils can be determined iteratively from measurements of the magnetic signature in the cardinal directions. In this paper the magnetic signatures are calculated using decomposition-based approach for each coil and each component of the external field separately. Hence the overall magnetic signature of the object can be reproduced in arbitrary external magnetic field (i.e. anywhere on the Earth). Knowing the influence of each coil, it is possible to formulate the optimization task (signature minimization) and determine the currents. The presented method is verified in FEM software with the use of engine models of both symmetrical and asymmetrical shapes. Since the determination of the currents takes place as a result of solving the optimization problem, the effectiveness of obtaining the results, the speed of convergence and the dependence on initial conditions is under investigation. The effect of the model mesh size on the quality of object signature reduction is also analyzed. The developed method can be used for a real object. In that case acquiring the data then requires the measurements of the object placed inside the Helmholtz coils.

  • Deep eutectic solvents – Ideal solution for clean air or hidden danger?
    • Farooque Janjhi
    • Roberto Castro Munoz
    • Grzegorz Boczkaj
    2023 SEPARATION AND PURIFICATION TECHNOLOGY

    The industrial sector is one of the fastest-growing sources of greenhouse gases, due to its excessive energy consumption to meet the rapidly growing demand for energy-intensive products. The use of deep eutectic solvents (DESs) has been studied extensively in order to cope with these harmful gases, but their usage can be an issue in respect to ecological reasons. Do deep eutectic solvents harm the atmosphere? Yes, these solvents can be harmful if their constituents (HBA and HBD) that are volatile and toxic in nature. A number of scientific reports preset their application without care on cross-contamination of treated media. Herein, we highlight the ecotoxicity behavior of DESs as treatment materials for three major toxic gas treatment methods, including carbon dioxide (CO2) capture, biogas treatment and air purification. Special attention is given to the health consequences of HBDs due to their toxicity and emission outside of the treatment system into the environment. The physicochemical characteristics of DESs are evaluated and addressed in comparison to the benchmark solvents. Emission of DESs can be predicted based on simulation software like COSMO-RS or Molecular Dynamics (MD). Furthermore, we suggest some simple protocols to estimate this issue and thus make aware researchers to think about it when experimenting with DES for different applications.

  • Deep eutectic solvents in analytical sample preconcentration Part B: Solid-phase (micro)extraction
    • Justyna Werner
    • Agnieszka Zgoła-Grześkowiak
    • Julia Płatkiewicz
    • Justyna Płotka-Wasylka
    • Natalia Jatkowska
    • Alina Kalyniukova
    • Serhii Zaruba
    • Vasil Andruch
    2023 MICROCHEMICAL JOURNAL

    One of the key challenges of modern analytical chemistry is the monitoring of trace amounts of contaminants using sensitive and selective instrumental techniques. Due to the variety and complexity of some samples, it is often necessary to properly prepare a sample and to perform a preconcentration of trace amounts of analytes. In line with the principles of Green Analytical Chemistry (GAC), it is important for an analytical procedure to reduce labor and time consumption and to decrease the use of volatile and hazardous solvents. Therefore, solvent-free extraction techniques, such as SPE, μSPE, SPME and their various modifications, which are mainly aimed at increasing their “greenness”, have been very popular for many years. Deep eutectic solvents fit perfectly into GAC principles, which is why they have been used as extractants in liquid-phase microextraction techniques for a long time. This review is a follow-up to our recently published article on the use of deep eutectic solvents (DESs) in liquid-phase microextraction techniques and summarizes the most important applications of DES in solid-phase (micro)extraction techniques.

  • Deep Eutectic Solvents: Properties and Applications in CO2 Separation
    • Iwona Cichowska-Kopczyńska
    • Bartosz Nowosielski
    • Dorota Warmińska
    2023 Full text MOLECULES

    Nowadays, many researchers are focused on finding a solution to the problem of global warming. Carbon dioxide is considered to be responsible for the “greenhouse” effect. The largest global emission of industrial CO2 comes from fossil fuel combustion, which makes power plants the perfect point source targets for immediate CO2 emission reductions. A state-of-the-art method for capturing carbon dioxide is chemical absorption using an aqueous solution of alkanolamines, most frequently a 30% wt. solution of monoethanolamine (MEA). Unfortunately, the usage of alkanolamines has a number of drawbacks, such as the corrosive nature of the reaction environment, the loss of the solvent due to its volatility, and a high energy demand at the regeneration step. These problems have driven the search for alternatives to that method, and deep eutectic solvents (DESs) might be a very good substitute. Many types of DESs have thus far been investigated for efficient CO2 capture, and various hydrogen bond donors and acceptors have been used. Deep eutectic solvents that are capable of absorbing carbon dioxide physically and chemically have been reported. Strategies for further CO2 absorption improvement, such as the addition of water, other co-solvents, or metal salts, have been proposed. Within this review, the physical properties of DESs are presented, and their effects on CO2 absorption capacity are discussed in conjunction with the types of HBAs and HBDs and their molar ratios. The practical issues of using DESs for CO2 separation are also described.

  • Deep-Learning-Based Precise Characterization of Microwave Transistors Using Fully-Automated Regression Surrogates
    • Nurullah Calik
    • Filiz Gunes
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    • Mehmet Belen
    • Peyman Mahouti
    2023 Full text Scientific Reports

    Accurate models of scattering and noise parameters of transistors are instrumental in facilitating design procedures of microwave devices such as low-noise amplifiers. Yet, data-driven modeling of transistors is a challenging endeavor due to complex relationships between transistor characteristics and its designable parameters, biasing conditions, and frequency. Artificial neural network (ANN)-based methods, including deep learning (DL), have been found suitable for this task by capitalizing on their flexibility and generality. Yet, rendering reliable transistor surrogates is hindered by a number of issues such as the need for finding good match between the input data and the network architecture and hyperparameters (number and sizes of layers, activation functions, data pre-processing methods), possible overtraining, etc. This work proposes a novel methodology, referred to as Fully Adaptive Regression Model (FARM), where all network components and processing functions are automatically determined through Tree Parzen Estimator. Our technique is comprehensively validated using three examples of microwave transistors and demonstrated to offer a competitive edge over the state-of-the-art methods in terms of modeling accuracy and handling the aforementioned issues pertinent to standard ANN-based surrogates.

  • Deformation of an elastic second gradient spherical body under equatorial line density of dead forces
    • Isola dell'Isola
    • Victor Eremeev
    • V Korolenko
    • Yuri Solyaev
    2023 EUROPEAN JOURNAL OF MECHANICS A-SOLIDS

    We consider deformations of an elastic body having initially a spherical shape. Assumed deformation energy depends on the first and second gradient of displacements. We apply an equatorial line density of dead loads, that are forces per unit line length directed in radial direction and applied along the equator of the sphere. We restrict ourselves our analysis to the case of linearized second strain gradient isotropic elasticity (for which the more general energy was determined by Mindlin) with only one characteristic length. Differently to what happens in first gradient continua, i.e. in classic linear elasticity, we show that for the particular class second gradient continua considered here these forces do not determine infinite displacements in the direction of applied dead line forces. Instead, using a series method for the solution of the considered boundary-value problem, we demonstrate that the displacements are finite. So in the deformed configuration there is not the formation of an edge at the material points where the forces are applied. Further investigations are therefore needed for establishing if this elastic-regime edge formation is made possible: (I) either in the case of more general linear elastic constitutive equations or (II) only when large deformations are considered or (III) if non-elastic phenomena are involved.

  • Degradation of bisphenol S – a contaminant of emerging concern - by synergistic ozone and percarbonate based AOP
    • Zahra Askarniya
    • Manoj P Rayaroth
    • Xun Sun
    • Zhaohui Wang
    • Grzegorz Boczkaj
    2023 Full text Water Resources and Industry

    Degradation of bisphenol S was studied using ozone activated by sodium percarbonate and the effectiveness of optimized process was compared with the peroxone process. The influence of several factors including sodium percarbonate concentration, ozone dose, pH, and water matrix were investigated. A synergetic coefficient of 3.84 was achieved for the combination of sodium percarbonate and ozone, confirming the effectiveness of this hybrid process. Scavenging tests revealed, that carbonate radicals, hydroxyl radicals, superoxide radicals, and singlet oxygen contributed to the degradation of bisphenol S. At the same operating condition, degradation effectiveness values of 99% and 81% were obtained by ozone combined with sodium percarbonate and hydrogen peroxide, respectively, demonstrating the superiority of sodium percarbonate over hydrogen peroxide in combination with ozone for the degradation of bisphenol S. Low concentration of inorganic anions had a negligible effect on the degradation, while carbonate ions increased the first-order degradation rate constant by 56%.

  • Degradation of cefadroxil drug by newly designed solar light responsive alcoholic template-based lanthanum ferrite nanoparticles
    • Ammara Nazir
    • Muhammad Imran
    • Farah Kanwal
    • Shoomaila Latif
    • Ayesha Javaid
    • Tak H. Kim
    • Grzegorz Boczkaj
    • Ashwag Shami
    • Hafiz M.N. Iqbal
    2023 ENVIRONMENTAL RESEARCH

    In this work, lanthanum ferrite nanoparticles were synthesized via a simple co-precipitation method. Two different templates, namely sorbitol and mannitol, were used in this synthesis to tune the optical, structural, morphological, and photocatalytic properties of lanthanum ferrite. The synthesized lanthanum ferrite-sorbitol (LFOCo-So) and lanthanum ferrite-mannitol (LFOCo-Mo) were investigated through Ultraviolet–Visible (UV–Vis), X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR), Raman, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), and photoluminescence (PL) techniques to study the effects of the templates on the tunable properties of lanthanum ferrite nanoparticles. The UV–Vis study revealed a remarkably small bandgap (2.09 eV) of LFOCo-So compared to the LFOCo-Mo having a band gap of 2.46 eV. XRD analysis revealed a single-phased structure of LFOCo-So, whereas LFOCo-Mo showed different phases. The calculated crystallite sizes of LFOCo-So and LFOCo-Mo were 22 nm and 39 nm, respectively. FTIR spectroscopy indicated the characteristics of metal-oxygen vibrations of perovskites in both lanthanum ferrite (LFO) nanoparticles, whereas a slight shifting of Raman scattering modes in LFOCo-Mo in contrast to LFOCo-So showed the octahedral distortion of the perovskite by changing the template. SEM micrographs indicated porous particles of lanthanum ferrite with LFOCo-So being more uniformly distributed, and EDX confirmed the stoichiometric ratios of the lanthanum, iron, and oxygen in the fabricated lanthanum ferrite. The high-intensity green emission in the photoluminescence spectrum of LFOCo-So indicated more prominent oxygen vacancies than LFOCo-Mo. The photocatalytic efficiency of synthesized LFOCo-So and LFOCo-Mo was investigated against cefadroxil drug under solar light irradiation. At optimized photocatalytic conditions, LFOCo-So showed higher degradation efficiency of 87% in only 20 min than LFOCo-Mo having photocatalytic activity of 81%. The excellent recyclability of the LFOCo-So reflected that it could be reused without affecting photocatalytic efficiency. These findings showed that sorbitol is a useful template for the lanthanum ferrite particles imparting outstanding features, enabling it to be used as an efficient photocatalyst for environmental remediation.

  • Degradation of Rhodamine dyes by Advanced Oxidation Processes (AOPs) – Focus on cavitation and photocatalysis - A critical review
    • Ashish V. Mohod
    • Malwina Momotko
    • Noor S. Shah
    • Mateusz Marchel
    • Mohammad Imran
    • Lingshuai Kong
    • Grzegorz Boczkaj
    2023 Full text Water Resources and Industry

    This review evaluates selected advanced oxidation processes (AOPs) - cavitation and photocatalysis - successfully used for wastewater treatment towards degradation of Rhodamine (Rh) dyes. Reactor configuration and impact of process parameters and oxidants addition (hydrogen peroxide, ozone, persulfates) on degradation effectiveness along with degradation mechanisms are discussed. Best technologies provide 100% degradation within 10–30 min. Rhodamine B is effectively degraded in highly acidic conditions (pH 2), while Rhodamine 6G requires basic conditions (pH 10). The most effective oxidants were hydrogen peroxide and ozone. Ecological Structure Activity Relationships (ECOSAR) revealed acute toxicities of the intermediates and by-products of the Rh dye.

  • Dehydrogenation in electron-induced dissociative ionization of pyridine molecule
    • Michał Jurkowski
    • Tomasz Wąsowicz
    2023 Full text Romanian Journal of Physics

    The electron-impact dissociative ionization of pyridine has been investigated using mass spectrometry. Thirty-two well-resolved mass peaks have been identified in the cation mass spectra and assigned to the most likely ionic molecular fragments. The new sixteen ionic fragments' appearance energies have been determined, and sixteen others remeasured. The total cross-section for electron-impact ionization of pyridine has been measured at 100 eV. Thorough analysis indicates that at least three peaks' groups in the mass spectra occur via the shake-off dehydrogenation mechanism, i.e., by sequential hydrogen atoms elimination from the pyridine parent cation or its fragmentation products. The nature of this process is deciphered.

  • Dekodowanie kodów iterowanych z użyciem sieci neuronowej
    • Oskar Fiedot
    • Marek Blok
    2023 Full text Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Nadmiarowe kody iterowane są jedną z prostych metod pozyskiwania długich kodów korekcyjnych zapewniających dużą ochronę przed błędami. Jednocześnie, chociaż ich podstawowy iteracyjny dekoder jest prosty koncepcyjnie oraz łatwy w implementacji, to nie jest on rozwiązaniem optymalnym. Poszukując alternatywnych rozwiązań zaproponowano, przedstawioną w pracy, strukturę dekodera tego typu kodów wspomaganą przez sieci neuronowe. Zaproponowane rozwiązanie pozwala na wykrywanie oraz korekcję błędów w odbieranych ciągach.

  • DEM Analyses of Interface Behaviour Between Cohesionless Sand and Rigid Wall of Different Roughness
    • Aleksander Grabowski
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    2023

    Artykuł dotyczy trójwymiarowych symulacji numerycznych quasi-statycznego ścinania między niespoistym piaskiem a sztywnymi ścianami w aparacie bezpośredniego ścinania ścian. Chropowatość ścian sztywnych wahała się od gładkiej do bardzo szorstkiej. Na górną ścianę działało stałe ciśnienie normalne. Symulacje numeryczne przeprowadzono metodą elementów dyskretnych (DEM). Ziarna piasku opisywano jako kulki z momentami kontaktowymi lub jako niesymetryczne nieregularne grudki. Zbadano wpływ chropowatości powierzchni na makroskopowe krzywe siła-przemieszczenie oraz na wyniki mikroskopowe na poziomie ziarna. Dla różnych chropowatości ścian obliczono wysokość strefy zlokalizowanej ścinania, rotacje ziaren oraz stosunek między poślizgami i rotacjami ziaren. Zaproponowano dwa różne warunki brzegowe wzdłuż ściany dla kontinuów mikropolarnych, biorąc pod uwagę rotacje i poślizgi ziaren oraz znormalizowaną chropowatość granicy faz. Wyniki DEM pozwalają lepiej zrozumieć zachowanie interfejsu między ciałami ziarnistymi a sztywnymi strukturami.

  • Dependent self-employed individuals: are they different from paid employees?
    • Ondřej Dvouletý
    • Dagmara Nikulin
    2023 Full text Employee Relations

    This study focuses on dependent self-employment, which covers a situation where a person works for the same employer as a typical worker while on a self-employment contractual basis, i.e., without a traditional employment contract and without certain rights granted to "regular" employees. The research exploits the individual-level dataset of 35 European countries extracted from the 2017 edition of the European Labour Force Survey and compares the characteristics of employees and dependent self-employed individuals. Methodologically, the study relies on the estimation of a multivariate logistic regression model. The main hypothesis assuming that dependent self-employed work most often in low-skilled occupations was empirically supported. There was also a non-linear (u-shaped) relationship between the years of accumulated experience (with a turning point at 35 years) and the likelihood of being dependent self-employed. Other results showed that dependent self-employed are less likely to be women, and they are more likely born outside of the countries where they participate in the labour markets. The study contributes to the field by adopting a comparable definition of dependent self-employment and exploiting the recent theoretical support of The Work Precarity Framework. The phenomenon should still be addressed by policymakers and labour office representatives, aiming to protect, primarily, vulnerable lower-skilled workers. The ongoing research should study the longitudinal dimension of dependent self-employment with a focus on motivational aspects.

  • Depolarisation Model for a BAN Indoor Scenario
    • Manuel M. Ferreira
    • Filipe D. Cardoso
    • Sławomir Ambroziak
    • Mariella Särestöniemi
    • Kenan Turbic
    • Luis M. Correia
    2023 Full text

    In this paper, an analysis of depolarisation in Body Area Networks for Body-to-Infrastructure communications based on a measurement campaign in the 5.8 GHz band in an indoor environment is performed. Measurements were made with an offbody antenna transmitting linearly polarised signals and dualpolarised receiving antennas carried by the user on the body. A Normal Distribution with a mean of 2.0 dB and a standard deviation of 4.3 dB is found to be the best fit for modelling crosspolarisation discrimination. The average correlation between the signals received by the orthogonally polarised antennas is below 0.5, showing that polarisation diversity can be used. A model is proposed for the average value of the standard deviation of the cross-polarisation discrimination ratio as a function of the transmitted polarisation, the mobility of users and link dynamics.

  • Der Begriff des Mythos bei Cassirer: zwischen UIdealismus, Ethnologie, politischer Philosophie und allgemeine Kulturphilosophie
    • Andrzej Karalus
    2023

    Der Mythos war eines der bevorzugten Forschungsobjekte Cassirers, denen er zwei Bücher, zahlreiche Artikel und wichtige längere Aufsätze widmete. In diesem Artikel versuche ich Cassirers Mythendeutung kurz zu rekapitulieren, um ihre Position in der Gesamtheit seines philosophischen Systems festzulegen und ihr Erklärungspotenzial zu gewinnen. In erstem Teil handle ich das allgemeine Problem des mythischen Denkens hauptsächlich aufgrund des zweiten Teils der Philosophie der symbolischen Formen ab. Ich möchte hierbei aufzeigen, dass der Mythos als symbolische Form einen Versuch der Vereinheitlichung der theoretischen Impulse des Deutschen Idealismus mit Feststellungen empirisch orientierter Kulturwissenschaften repräsentiert. Im zweiten Teil bespreche ich das Problem des Mythos aus Sicht der politischen Philosophie und im Hinblick auf die Totalitarismus-Debatte. In drittem Teil bespreche ich schließlich die Vorteile und Beschränkungen der Konzeption des totalitären Staates Cassirers und versuche seine Mythenauffassung in seine allgemeine Kulturphilosophie einzupflegen. Ich schlage vor, dass der Schlüssel zur fruchtbarsten Behandlung dieser Thematik vorerst in Das mythischen Denken zu finden ist, nicht in The Myth of the State. Ich weise auch auf die potentiellen Anwendungsbereiche seiner Betrachtungen hin.

  • Design advantages and analysis of a novel five-phase doubly-fed induction generator
    • Roland Ryndzionek
    • Michał Michna
    • Filip Kutt
    • Grzegorz Kostro
    • Krzysztof Blecharz
    2023 Full text COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING

    Purpose – The purpose of this paper is to provide an analysis of the performance of a new five-phase doubly fed induction generator (DFIG). Design/methodology/approach – This paper presents the results of a research work related to fivephase DFIG framing, including the development of an analytical model, FEM analysis as well as the results of laboratory tests of the prototype. The proposed behavioral level analytical model is based on the winding function approach. The developed DFIG model was used at the design stage to simulate the generator’s no-load and load state. Then, the results of the FEM analysis were shown and compared with the results of laboratory tests of selected DFIG operating states. Findings – The paper provides the results of analytical and FEM simulation and measurement tests of the new five-phase dual-feed induction generator. The use of the MATLAB Simscape modeling language allows for easy and quick implementation of the model. Design assumptions and analytical model-based analysis have been verified using FEM analysis and measurements performed on the prototype. The results of the presented research validate the design process as well as show the fivephase winding design advantage over the three-phase solution regarding the control winding power quality. Research limitations/implications – The main disadvantage of the winding function approach-based model development is the simplification regarding omitting the tangential airgap flux density component. However, this fault only applies to large airgap machines and is insignificant in induction machines. The results of the DFIG analyses were limited to the basic operating states of the generator, i.e. the no-load state, the inductive and resistive load. Practical implications – The novel DFIG with five phase rotor control winding can operate as a regular three-phase machine in an electric power generation system and allows for improved control winding power quality of the proposed electrical energy generation system. This increase in power quality is due to the rotor control windings inverter-based PWM supply voltage, which operates with a wider per-phase supply voltage range than a three-phase system. This phenomenon was quantified using control winding current harmonic analysis.

  • Design and Evaluation of the Compact and Autonomous Energy Subsystem of a Wave Energy Converter
    • Marcin Drzewiecki
    • Jarosław Guziński
    2023 Full text ENERGIES

    This paper presents the results of the design process focused on the development of the energy subsystem (ES) of a wave energy converter (WEC). The ES is an important electrical part that significantly affects the energy reliability and energy efficiency of the entire WEC device. The designed ES was intended for compact WECs powering IoT network devices working in the distributed grid. The developed ES is an electronic circuit consisting of three cooperating subsystems used for energy conversion, energy storage, and energy management. The energy conversion subsystem was implemented as a set of single-phase bridge rectifiers. The energy storage subsystem was a battery-less implementation based on the capacitors. The energy management subsystem was implemented as a supervisory circuit and boost converter assembly. The designed ES was verified using the physical experiment method. The model experiment reflected the operation of the designed ES with a piezoelectric PZT-based WEC. The experimental results showed a 41.5% surplus of the energy supplied by ES over the energy demanded by the considered load at a duty cycle of ca. 6 min—37.2 mJ over 26.3 mJ, respectively. The obtained results have been evaluated and discussed. The results confirmed the designed ES as a convenient solution, which makes a significant contribution to the compact WECs that can be applied among others to a distributed grid of autonomous IoT network devices powered by free and renewable energy of sea waves. Finally, it will also enable sustainable development of mobile and wireless communication in those maritime areas where other forms of renewable energy may not be available.

  • Design and Optimization of a Compact Super-Wideband MIMO Antenna with High Isolation and Gain for 5G Applications
    • Bashar Esmail
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2023 Full text Electronics

    This paper presents a super-wideband multiple-input multiple-output (SWB MIMO) antenna with low profile, low mutual coupling, high gain and compact size for microwave and millimeter wave (mm-wave) fifth-generation (5G) applications. A single antenna is a simple elliptical-square shape with a small physical size of 20 × 20 × 0.787 mm3. The combination of both square and elliptical shapes results in an exceptionally broad impedance bandwidth spanning from 3.4 to 70 GHz. An-tenna dimensions are optimized using the trust-region algorithm to enhance its impedance band-width, and maintain the gain within a predefined limit across the entire band. For that purpose, regularized merit function is defined, which permits to control both the single antenna reflection response and gain. Subsequently, the SWB MIMO system is constructed with four radiators ar-ranged orthogonally. This arrangement results in high isolation, better than 20 dB, over a fre-quency band from 3.4 to 70 GHz band. Further, the system achieves an average gain of approxi-mately 7 dB below 45 GHz and a maximum gain equal to 12 dB for 70 GHz. The system exhibits excellent diversity performance throughout the entire bandwidth, as evidenced by the low enve-lope correlation coefficient (ECC) (<3∙10−3), total active reflection coefficient (TARC) (≤−10 dB), and channel capacity loss (CCL) (<0.3 bit/s/Hz) metrics, as well as high diversity gain (DG) of approxi-mately 10 dB. Experimental validation of the developed SWB MIMO demonstrates a good match-ing between the measurements and simulations.

  • Design and Optimization of Metamaterial-Based 5G Millimeter Wave Antenna for Gain Enhancement
    • Bashar Esmail
    • Sławomir Kozieł
    2023 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS

    In this brief, a low profile, broadband, high-gain antenna array based on optimized metamaterials (MMs) with dual-beam radiation is reported for 5G millimeters wave (mm-wave) applications. The design is a simple bow tie operating at a 5G band of 28 GHz. It consists of two bow ties with substrate integrated waveguide (SIW)-based power splitter. A broad impedance bandwidth of 26.3−29.8 GHz is obtained by appropriately combining the resonances of the bow ties and the SIW. Further, the antenna exhibits symmetrical dual-beam radiation at ±25˚ over a broad bandwidth in the end-fire direction due to the arrangement of the two radiators. A MM array has been etched in the same substrate shared with the antenna to improve the gain performance while preserving compact size. The trust-region (TR) gradient-based algorithm is used to optimize the structure dimensions and to achieve a maximum gain of 12.2 dB at 29 GHz. The developed MM-based antenna is validated experimentally with a good matching between the simulated and measured data. The system features a small size, low profile, high gain, broad bandwidth, and dual-beam in the E-plane, demonstrating its suitability for 5G mm-wave indoor scenarios.

  • Design and Preparation of Magnetically-Oriented Poly(styr-co-MMA)-3MPS Capped Fe(ZnO) Hybrid Microspheres for Ion Exchange Removal of Toxic Pollutants from Wastewater
    • Sahar Fatima
    • Muhammad Imran
    • Farah Kanwal
    • Ayesha Javaid
    • Shoomaila Latif
    • Grzegorz Boczkaj
    2023 Full text Water

    In this work, polymeric microspheres derived from polystyrene-co-methyl methacrylate embedded with magnetic ZnO nanoparticles (poly(styrene-co-MMA)-3MPS-Fe (ZnO)) were synthesized using the suspension polymerization method. The surfaces of polymeric Fe(ZnO) microspheres were improved by functionalization with amino and sulphonate groups. The physicochemical analysis indicated a large number of positively charged (anion exchange) groups (91 mmol/g) on the amine-modified polymeric microsphere (MFZPI) and a large number of negatively charged (cation exchange) groups (90 mmol/g) on the sulphonate-modified polymeric microsphere (SMFZPI)—revealing ambivalent character of obtained sorbent. The characterization of the synthesized compounds using various analytical techniques such as TGA, FTIR, XRD, SEM/EDX, UV-VIS and VSM indicated that synthesized microspheres were thermally stable, semi-crystalline in structure with hollow irregular morphology, optically active in UV region and slightly magnetic in nature. Due to the introduction of groups having ion exchange properties, these modified poly(styrene-co-MMA)-3MPS-Fe(ZnO) microspheres were used for the ion exchange sorptive removal of Cr(III) and fluorescein from aqueous matrix. The equilibrium sorption capacity of Cr(III) was 16.79 mg/g whereas of fluorescein was 12.03 mg/g under optimized conditions. Therefore, SMFZPI was found to be a promising sorbent for both cationic heavy metals and anionic dyes due to the presence of both acidic and basic groups. The mathematical modelling revealed that the sorption phenomenon followed pseudo-second-order kinetics with Freundlich equilibrium isotherm, indicating multilayer chemisorption of the pollutants on the synthesized ion exchange sorbents. This work establishes the utilization of polymeric magnetic ZnO-based ion exchange sorbents to effectively remove harmful toxins from wastewater.

  • Design and Synthesis of NTU-9/C3N4 Photocatalysts: Effects of NTU-9 Content and Composite Preparation Method
    • Damian Makowski
    • Wojciech Lisowski
    • Mateusz Baluk
    • Tomasz Klimczuk
    • Beata Bajorowicz
    • Mateusz Adam Baluk
    2023 Full text Materials

    Hybrid materials based on graphitic carbon nitride (g-C3N4) and NTU-9 metal–organic frameworks (MOF) were designed and prepared via solvothermal synthesis and calcination in air. The as-prepared photocatalysts were subsequently characterized using Brunauer–Emmett–Teller (BET) analysis, UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) emission spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The obtained NTU-9/C3N4 composites showed a greatly improved photocatalytic performance for the degradation of toluene in the gas phase under LED visible-light irradiation (max = 415 nm). The physicochemical properties and photocatalytic activities of the obtained NTU- 9/C3N4 materials were tuned by varying the NTU-9 content (5–15 wt%) and preparation method of the composite materials. For composites prepared by calcination, the photocatalytic activity increased with decreasing NTU-9 content as a result of the formation of TiO2 from the MOFs. The best photocatalytic performance (65% of toluene was photodegraded after 60 min) was achieved by the NTU-9/C3N4 sample prepared via the solvothermal method and containing 15 wt% MOF, which can be attributed to the appropriate amount and stable combination of composite components, efficient charge separation, and enhanced visible-light absorption ability. The photocatalytic mechanisms of the prepared hybrid materials depending on the preparation method are also discussed.

  • Design and synthesis of TiO2/Ti3C2 composites for highly efficient photocatalytic removal of acetaminophen: The relationships between synthesis parameters, physicochemical properties, and photocatalytic activity
    • Anna Grzegórska
    • Agnieszka Gajewicz-Skrętna
    • Grzegorz Trykowski
    • Karol Sikora
    • Anna Zielińska-Jurek
    2023 Full text CATALYSIS TODAY

    In this study, we report the potential of TiO2/Ti3C2 composite fabricated by oxidation of MXene for degradation of persistent organic pollutants. The effect of the synthesis conditions (time, temperature, and reaction environment) on the morphology, physicochemical properties, and photocatalytic activity was investigated. It was found that acetaminophen degradation was positively correlated with TiO2 content in the composite structure. Furthermore, the findings confirmed that the synthesis reaction environment strongly influenced the obtained materials photocatalytic activity. The TiO2/Ti3C2 composite obtained by solvothermal route in the presence of hydrochloric acid and ammonium fluoride exhibited the highest efficiency towards acetaminophen degradation than other composite materials, for which ACT removal reached 92 % within 60 min of irradiation under simulated solar light. The improved photocatalytic performance can be attributed to the presence of anataserutile polymorphs exposing highly active { 0 0 1} and { 1 0 1} facets coupled with MXene. Superoxide anion radicals and hydroxyl radicals played a major role in ACT degradation. Moreover, 3-hydroxyacetaminophen was detected as the first intermediate of ACT degradation, leading quickly to aromatic ring opening and production of aliphatic acids. Overall, this work provides an effective strategy for designing novel and efficient MXene-based photocatalysts for the degradation of emerging contaminants in water systems.

  • Design of an Autonomous IoT Node Powered by a Perovskite-Based Wave Energy Converter
    • Marcin Drzewiecki
    • Jarosław Guziński
    2023 Full text Polish Maritime Research

    This paper presents the results of experimental research focused on wave energy harvesting and its conversion to power Internet of Things (IoT) devices. The harvesting and conversion process was performed using a wave energy converter (WEC) consisting of a lead zirconate titanate piezoelectric ceramic perovskite material and a prototype power electronic circuit. The designed WEC was considered as a power supply for an end node device (END) of an IoT network. The END consisted of a long-range radio module and an electronic paper display. A set of physical experiments were carried out, and the results confirmed that an energy surplus was supplied by WEC compared to the energy consumed by the END. Hence, the proposed scheme was experimentally validated as a convenient solution that could enable the autonomous operation of an IoT device. The use case presented here for the proposed WEC was analysed for selected sea areas on the basis of wave statistics. The novelty of this paper arises from an investigation that confirms that WECs can significantly contribute to the development of wireless and mobile IoT communication powered by freely available sea wave energy.

  • Design of compact self-quintuplexing antenna with high-isolation for penta-band applications
    • Rusan Kumar Barik
    • Sławomir Kozieł
    2023 Full text IEEE Access

    This article presents a novel compact self-quintuplexing antenna architecture based on a substrate-integrated rectangular cavity (SIRC) for pentaband applications. The proposed self-quintuplexing antenna is constructed by employing an SIRC, one Pi-shaped slot (PSS), one T-shaped slot (TSS), and five 50Ω microstrip feedlines. The PSS and TSS are engraved on the top of the SIRC to create five radiating patches, which are excited by five 50Ω feedlines to achieve pentaband operation with self-quintuplexing characteristics. The resonating frequencies can be tuned independently based on the dimension of the radiator without disturbing other bands. A detailed parametric analysis is carried out to provide a suitable frequency tunable range and high isolation. In addition, an equivalent lumped circuit is developed to analyze the proposed self-quintuplexing antenna. To validate the proposed antenna architecture, an SIRC-based self-quintuplexing antenna operating at 2.29, 2.98, 3.65, 4.37, and 5.08 GHz is fabricated and demonstrated. The fabricated antenna offers competitive performance with a compact size of 0.173λ2, pentaband operation, high isolation of 29.31 dB, and a wide frequency tunability range from 2.29 GHz to 6.03 GHz. Furthermore, the fabricated self-quintuplexing antenna exhibits the measured realized gain of 3.59, 4.55, 3.91, 5.70, and 4.92dBi at 2.29, 2.98, 3.64, 4.37, and 5.08 GHz, respectively.

  • Design of Frequency-Reconfigurable Branch-Line Crossover Using Rectangular Dielectric Channels
    • Rusan Kumar Barik
    • Sławomir Kozieł
    • Eirikur Bernhardsson
    2023 Full text IEEE Access

    This paper presents an efficient yet straightforward passive reconfiguration technique to tune the operating frequency of a branch-line crossover (BLCO). The underlying principle is to fill rectangular dielectric channels (RDCs) prepared beforehand with either air or materials of different relative permittivity. Two configurations (one RDC and three RDCs in each arm) of the branch-line crossover are employed to estimate the tunability range of the operating frequency. The introduction of RDCs packed with different materials in the branch lines modifies the effective permittivity of the dielectric medium, resulting in an alteration of the operating frequency. The size and the positions of the RDCs are optimized using full-wave electromagnetic simulations to achieve maximum tunability range while ensuring reasonable bandwidth. A lumped circuit model (LCM) is developed to analyze the working principle of the proposed technique. To validate computational models, two prototypes of the branch-line crossover are realized, fabricated, and experimentally demonstrated. The first BLCO packed with seven RDCs exhibits a frequency tuning range of 15.8%, whereas the second prototype filled with twenty-one RDCs features a tuning range of 36.9%.

  • Design of metamaterials: Preface
    • Anil Misra
    • François Hild
    • Victor Eremeev
    2023 Full text MECHANICS RESEARCH COMMUNICATIONS

    This special issue “Design of metamaterials” collects several papers that have presented theoretical, numerical, and experimental studies of metamaterials.

  • Design of novel highly sensitive sensors for crack detection in metal surfaces: theoretical foundation and experimental validation
    • Zahra Shaterian
    • Ali Karami Horestani
    • Ferran Martin
    • Michał Mrozowski
    2023 Full text Scientific Reports

    The application of different types of microwave resonators for sensing cracks in metallic structures has been subject of many studies. While most studies have been focused on improving the sensitivity of planar crack sensors, the theoretical foundation of the topic has not been treated in much detail. The major objective of this study is to perform an exhaustive study of the principles and theoretical foundations for crack sensing based on planar microwave resonators, especially defective ground structures (DGS) including complementary split ring resonators (CSRRs). The analysis is carried out from the equivalent circuit model as well as the electromagnetic (EM) field perspectives, and guidelines for the design of crack sensors with high sensitivity are developed. Numerical and experimental validation of the provided theoretical analysis is another aim of this article. With this aim, the developed guidelines are used to design a crack sensor based on a single-ring CSRR. It is shown that the sensitivity of the proposed sensor is almost three times higher than the sensitivity of a conventional double-ring CSRR. Moreover, it is demonstrated that folded dumbbell-shape DGS resonators can be used to achieve even higher sensitivities. The CSRR-based crack sensors presented in this study and other studies available in the literature are only sensitive to cracks with a specific orientation. To address this limitation, a modified version of the DGS is proposed to sense cracks with arbitrary orientations at the cost of lower sensitivity. The performance of all the presented sensors is validated through EM simulation, equivalent circuit model extraction, and measurement of the fabricated prototypes.

  • Designing efficient A-D-A1-D-A type fullerene free acceptor molecules with enhanced power conversion efficiency for solar cell applications
    • Malik Muhammad Iqbal Asif
    • Muhammad Arshad
    • Muhammad Yasir Mehboob
    • Muhammad Khan
    • Sanwal Piracha
    2023 SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

    The achievement of highly efficient power conversion efficiency (PCE) is a big concern for non-fullerene organic solar cells (NF-OSCs) because PCE can depend on numerous variables. Here, new five novel acceptor molecules without fullerenes were developed and investigated using DFT (density functional theory) and TD-DFT (time dependent-density functional theory). Compared to the recently synthesized molecule (PZ-dIDTC6), the developed molecules display a narrow optical band gap, exhibiting a red shift in the absorption spectrum. The developed molecules (YM1-YM5) express high mobility of electrons and holes in the active layer of OSCs (organic solar cells). In addition, high open-circuit voltage (Voc) values with maximum charge density shifting are noted in designed molecules. YM1-YM5 is also associated with low binding energy and excitation energy. This work proves that noncovalent conformational locking is favourable for improving PCE devices.

  • Detecting Lombard Speech Using Deep Learning Approach
    • Krzysztof Kąkol
    • Grazina Korvel
    • Gintautas Tamulevicius
    • Bożena Kostek
    2023 Full text SENSORS

    Robust Lombard speech-in-noise detecting is challenging. This study proposes a strategy to detect Lombard speech using a machine learning approach for applications such as public address systems that work in near real time. The paper starts with the background concerning the Lombard effect. Then, assumptions of the work performed for Lombard speech detection are outlined. The framework proposed combines convolutional neural networks (CNNs) and various two-dimensional (2D) speech signal representations. To reduce the computational cost and not resign from the 2D representation-based approach, a strategy for threshold-based averaging of the Lombard effect detection results is introduced. The pseudocode of the averaging process is also included. A series of experiments are performed to determine the most effective network structure and the 2D speech signal representation. Investigations are carried out on German and Polish recordings containing Lombard speech. All 2D signal speech representations are tested with and without augmentation. Augmentation means using the alpha channel to store additional data: gender of the speaker, F0 frequency, and first two MFCCs. The experimental results show that Lombard and neutral speech recordings can clearly be discerned, which is done with high detection accuracy. It is also demonstrated that the proposed speech detection process is capable of working in near real-time. These are the key contributions of this work.

  • Detecting type of hearing loss with different AI classification methods: a performance review
    • Michał Kassjański
    • Marcin Kulawiak
    • Tomasz Przewoźny
    • Dmitry Tretiakow
    • Jagoda Kuryłowicz
    • Andrzej Molisz
    • Krzysztof Koźmiński
    • Aleksandra Kwaśniewska
    • Paulina Mierzwińska-Dolny
    • Miłosz Grono
    2023

    Hearing is one of the most crucial senses for all humans. It allows people to hear and connect with the environment, the people they can meet and the knowledge they need to live their lives to the fullest. Hearing loss can have a detrimental impact on a person's quality of life in a variety of ways, ranging from fewer educational and job opportunities due to impaired communication to social withdrawal in severe situations. Early diagnosis and treatment can prevent most hearing loss. Pure tone audiometry, which measures air and bone conduction hearing thresholds at various frequencies, is widely used to assess hearing loss. A shortage of audiologists might delay diagnosis since they must analyze an audiogram, a graphic representation of pure tone audiometry test results, to determine hearing loss type and treatment. In the presented work, several AI-based models were used to classify audiograms into three types of hearing loss: mixed, conductive, and sensorineural. These models included Logistic Regression, Support Vector Machines, Stochastic Gradient Descent, Decision Trees, RandomForest, Feedforward Neural Network (FNN), Convolutional Neural Network (CNN), Graph Neural Network (GNN), and Recurrent Neural Network (RNN). The models were trained using 4007 audiograms classified by experienced audiologists. The RNN architecture achieved the best classification performance, with an out-of-training accuracy of 94.46\%. Further research will focus on increasing the dataset and enhancing the accuracy of RNN models.