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Publications Repository
Gdańsk University of Technology

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  • Transformator z tyrystorowym przełącznikiem zaczepów jako obiekt sterowania
    • Piotr Sępka
    • Maciej Brzycki
    • Artur Cichowski
    2022 Full text

    Artykuł jest wynikiem realizacji studenckich projektów, których obiektem badań były transformatory z tyrystorowym podobciążeniowym przełącznikiem zaczepów (PPZ), znajdujące się w Laboratorium LINTE^2. Pierwszy projekt obejmował analizę stanów przejściowych zachodzących podczas przełączania tyrystorów. W referacie przedstawiono opracowany model tyrystorowego przełącznika zaczepów wraz z przykładowymi wynikami. Drugi projekt skutkował utworzeniem translatora komunikacyjnego w oparciu o sterownik WAGO PFC200, który umożliwia reprezentację modelu danych urządzeń niezgodnych z normą IEC 61850, jako zgodne z tym standardem

  • Transmisja w kanale hydroakustycznym w warunkach NLOS
    • Agnieszka Czapiewska
    • Ryszard Studański
    • Andrzej Żak
    2022 Full text Przegląd Elektrotechniczny

    Transmisja danych w kanale hydroakustycznym w warunkach NLOS (ang. Non-Line-Of-Sight) jest szczególnie problematyczna. Dlatego podjęto próbę opracowania bezprzewodowej komunikacji podwodnej i jej przebadanie w warunkach NLOS. Zastosowano modulację MFSK (ang. Multiple Frequency-Shift Keying), przesyłając pojedynczy bit na dwóch nośnych, oraz odbiór zbiorczy. Uzyskane wyniki potwierdziły przydatność opracowanej techniki do transmisji danych w kanale hydroakustycznym w warunkach NLOS.

  • Trees as a solar control measure for southern-oriented street frontages. Analysis of a selected street model for a humid continental climate
    • Katarzyna Zielonko-Jung
    • Justyna Janiak
    2022 Full text URBAN ECOSYSTEMS

    The present study is aimed at the analysis of possibilities for shading southern frontage of street oriented along the E-W axis by the single row of trees, parallel to the southern elevations. The effectiveness of solar control shading was tested depending on the geometric relationships between trees and buildings. Numerical simulation analyses were conducted in Rhinoceros® program for the street located in humid continental climate in city Płock, Poland (52°32′50 “N 19°42’00 “E), for the day of the highest degree of total solar radiation in the year i.e. June 7th, during hours: 8.00a.m - 5.00 p.m. The analysis has proved that a row of 20–25 year old Sycamore Maple ‘Rotterdam’ in the street 30 m wide and 18 m high (H/W = 0.6), can provide solar protection for the southern frontage, especially when trees are located no more than 4 m away. Location of greenery within the range of 4 to 5 m from the buildings leads to a radical reduction in the possibility of shading the wall surfaces (at 5 m to 0%). Over 90% of the shading area of the ground floor façade walls was found when trees were within the distance 2 and 3 m away from the building.

  • Trends in the new generation of green solvents in extraction processes
    • Patrycja Janicka
    • Justyna Płotka-Wasylka
    • Natalia Jatkowska
    • Aneta Chabowska
    • Michel Y. Fares
    • Vasil Andruch
    • Massoud Kaykhaii
    • Jacek Gębicki
    2022 Full text Current Opinion in Green and Sustainable Chemistry

    Analytical chemistry, like other scientific fields, has undergone a number of changes to make it more consistent with the concept of sustainable development. Among the various steps of chemical analysis, without a doubt, sample preparation is the bottleneck in regard to following a green protocol, especially in terms of solvent consumption. Therefore, many attempts have been made to improve the environmental friendliness of this stage, mainly through the developing approaches for miniaturized sample preparation as well as application of new green solvents. This review offers a brief discussion of current trends in analytical applications that have been less studied and discussed: a new generation of green solvents, such as bio-based solvents, supercritical fluids, and liquefied. We believe that this mini review is a good starting place for readers interested in the future of green analytical chemistry.

  • Trendy w kształtowaniu nowoczesnych dzielnic badawczo-rozwojowych i przemysłowo-logistycznych
    • Karolina Krośnicka
    2022

    Tekst opisuje aktualne trendy w kształtowaniu przestrzennym nowoczesnych dzielnic badawczo-rozwojowych oraz przemysłowych i logistycznych.

  • Tribological Properties of Thermoplastic Materials Formed by 3D Printing by FDM Process
    • Jacek Łubiński
    2022 Full text

    The dataset entitled 3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 019_h_4 contains: the time base (expressed in seconds and minutes), the friction torque for sliding friction, rotational velocity of the counter – specimen (velocity of sliding), friction coefficient, load in the friction contact interface, specimen temperature. Tests were conducted in an in-house developed tribological tester, the Tribometr PT-1. The test belongs to a testing program on the influence of technological parameters in 3D printing from thermoplastic materials by FDM process on friction in sliding with a steel counter – specimen without added lubrication.

  • Tripping of F-type RCDs for sinusoidal residual current with superimposed smooth DC component
    • Stanisław Czapp
    • Hanan Tariq
    2022

    Recent trends in green energy development make that photovoltaics and electric vehicles are applied on an increasing scale. In both photovoltaic and electric vehicle charging installations, a significant value of DC component of the earth fault current may appear, which is a challenge, in particular, for commonly used residual current devices (RCDs). This paper presents results of the laboratory test on the operation of F-type RCDs – a type that is just beginning to appear in low-voltage installations. It has been checked how the tripping threshold of RCDs changes, if a smooth DC component is superimposed on the sinusoidal alternating current. It has been found that the F-type RCDs can operate very well even in the presence of a very high value of DC component.

  • Trójfazowy 4-gałęziowy falownik SiC w napędzie z wysokoobrotowym silnikiem indukcyjnym
    • Marek Adamowicz
    • Sebastian Giziewski
    • Zbigniew Krzemiński
    2022

    Zastosowanie tranzystorów SiC w falownikach napędów wysokoobrotowych powoduje nowe wyzwania, szczególnie odnośnie generowanego w falowniku napięcia common mode (CM) o wysokiej częstotliwości. Wysokoczęstotliwościowe napięcie CM wchodzi w interakcję z pojemnościami pasożytniczymi falownika, kabla i silnika wymuszając przepływ prądów CM, które są źródłem strat w filtrach pasywnych oraz powodują zakłócenia pomiarów prądów, nieakceptowalne z punktu widzenia działania przekształtnika. Ze wzrostem częstotliwości rośnie poziom emisji zaburzeń elektromagnetycznych spowodowany rezonowaniem obwodu CM, a tym samym niekorzystnie rośnie masa, gabaryt i koszt dławików CM. W referacie zaproponowano zastosowanie 4-gałęziowego falownika SiC z metodą sterowania zapewniającą eliminację napięcia CM celem poprawy właściwości napędu wysokoobrotowego.

  • Trust and Distrust in e-Democracy
    • David Duenas Cid
    • Tomasz Janowski
    • Robert Krimmer
    2022

    In the digital government research literature, the concept of trust is typically used as a precondition for the adoption of digital technology in the public sector or an outcome of a roadmap leading up to such adoption. The concept plays a central role in many decisions linked to the planning, adoption and management of the public sector technology. In contrast, the concept of distrust is almost neglected in such literature but, when approached, it appears as the opposite logical side of the trust-distrust dichotomy. However, we conjecture that the path to building trust is different than the path to building distrust and both concepts should be regarded as different theoretical constructs. The workshop aims to prove this conjecture drawing on the insights from the field of e-democracy including internet voting. Given its technical breadth, political and societal implications, and layers of complexity, e-democracy is a good benchmark for exploring this topic. The workshop will confront the main conjecture using examples, research and experiences contributed by participants, conceptual and methodological tools introduced by the organizers, and a discussion shared by everybody. The outcome – elements that help build trust or distrust in various forms of e-democracy – will have practical and theoretical implications, aiming at further research by the participants and collective publication of the results in a special issue in a top ranked journal, preferably Government Information Quarterly.

  • Trust in Electronic Word-of-Mouth (eWOM): the concept and the most important determinants
    • Anna Drapińska
    2022

    eWOM and trust in it is now the most important factor in determining buyers' purchasing behavior. Familiarity with the determinants of trust establishes the formation of appropriate marketing activities. However, the growing number of new forms of eWOM and its increasingly complex and multidimensional nature have created a lot of confusion. The article aims to organize the concepts related to trust in eWOM, to indicate the most important known determinants and future research directions. Thanks to the analysis of the literature, it was shown that future research on trust in eWOM should take into account more advanced models that include the multidimensionality of eWOM and trust, as well as individual product categories and customer characteristics.

  • Trustworthy Applications of ML Algorithms in Medicine - Discussion and Preliminary Results for a Problem of Small Vessels Disease Diagnosis.
    • Maria Ferlin
    • Zuzanna Klawikowska
    • Julia Niemierko
    • Małgorzata Grzywińska
    • Arkadiusz Kwasigroch
    • Edyta Szurowska
    • Michał Grochowski
    2022 Full text

    ML algorithms are very effective tools for medical data analyzing, especially at image recognition. Although they cannot be considered as a stand-alone diagnostic tool, because it is a black-box, it can certainly be a medical support that minimize negative effect of human-factors. In high-risk domains, not only the correct diagnosis is important, but also the reasoning behind it. Therefore, it is important to focus on trustworthiness which is a concept that includes fairness, data security, ethics, privacy, and the ability to explain model decisions, either post-hoc or during the development. One of the interesting examples of a medical applications is automatic SVD diagnostics. A complete diagnosis of this disease requires a fusion of results for different lesions. This paper presents preliminary results related to the automatic recognition of SVD, more specifically the detection of CMB and WMH. The results achieved are presented in the context of trustworthy AI-based systems.

  • t-SNE Highlights Phylogenetic and Temporal Patterns of SARS-CoV-2 Spike and Nucleocapsid Protein Evolution
    • Gaik Tamazian
    • Andrey Komissarov
    • Dmitry Kobak
    • Dmitry Polyakov
    • Evegeny Andronov
    • Sergei Nechaev
    • Sergey Kryzhevich
    • Yuri Porozov
    • Eugene Stepanov
    2022

    We propose applying t-distributed stochastic neighbor embedding to protein sequences of SARS-CoV-2 to construct, visualize and study the evolutionary space of the coronavirus. The basic idea is to explore the COVID-19 evolution space by using modern manifold learning techniques applied to evolutionary distances between variants. Evolutionary distances have been calculated based on the structures of the nucleocapsid and spike proteins.

  • Tuning Electrochemical Performance by Microstructural Optimization of the Nanocrystalline Functional Oxygen Electrode Layer for Solid Oxide Cells
    • Bartosz Kamecki
    • Grzegorz Cempura
    • Piotr Jasiński
    • Sea-Fue Wang
    • Sebastian Molin
    2022 Full text ACS Applied Materials & Interfaces

    Further development of solid oxide fuel cell (SOFC) oxygen electrodes can be achieved through improvements in oxygen electrode design by microstructure miniaturisation alongside nanomaterials implementation. In this work, improved electrochemical performance of an La0.6Sr0.4Co0.2Fe0.8O3-d (LSCF) cathode was achieved by the controlled modification of the La0.6Sr0.4CoO3-d (LSC) nanocrystalline interlayer introduced between a porous oxygen electrode and dense electrolyte. The evaluation was carried out for various LSC layer thicknesses, annealing temperatures, oxygen partial pressures, and temperatures, as well as subjected to long-term stability tests and evaluated in typical operating conditions in an intermediate temperature SOFC. Electrochemical impedance spectroscopy (EIS) and a distribution of relaxation times analysis (DRT) were performed to reveal the rate-limiting electrochemical processes that limit the overall electrode performance. The main processes with an impact on the electrode performance were the adsorption of gaseous oxygen O2, dissociation of O2, and charge transfer-diffusion (O2-). The introduction of a nanoporous and nanocrystalline interlayer with extended electrochemically active surface area accelerates the oxygen surface exchange kinetics and oxygen ion diffusions, reducing polarisation resistances. The polarisation resistance of the reference LSCF was lowered by one order of magnitude from 0.77Ω∙cm2 to 0.076 Ω∙cm2 at 600°C by the deposition of a 400 nm LSC interlayer at the interface. The developed electrode tested in the anode-supported fuel cell configuration showed a higher cell performance by 20% compared to the cell with the reference electrode. The maximum power density at 700°C reaches 675 and 820 mW∙cm-2 for the reference cell and the cell with the LSC interlayer, respectively. Ageing tests at 700°C under a high load of 1 A∙cm2 were performed.

  • Tuning of the finesse coefficient of optoelectronic devices
    • Monika Kosowska
    2022 Full text

    Optoelectronic devices attracted considerable attention in many branches of science and technology, which can be attributed to their unique properties. Many of them use optical cavities which parameters can be adopted to specific requirements. This thesis investigates the introduction of diamond structures (nitrogen-doped diamond film, boron-doped diamond film, undoped diamond sheet) to optical cavities to tune their finesse coefficient. Moreover, their application enabled development of a system for optical monitoring of electrochemical reactions. A detailed review of the state-of-the-art presents techniques of cavities tuning in optoelectronic devices, diamond applications in optoelectronics and current solutions combining optical and electrochemical measurement techniques in one system is presented. The work includes mathematical investigation, description of the construction of cavities and measurement setup, as well as results of experimental measurements. Applications of optical cavities tuned by the use of diamond structures are presented on the example of fiber-optic sensors: for measurements of distance and liquids refractive index, and for construction of a hybrid optoelectrochemical system.

  • Tuning the Laser-Induced Processing of 3D Porous Graphenic Nanostructures by Boron-Doped Diamond Particles for Flexible Microsupercapacitors
    • Sujit Deshmukh
    • Paweł Jakóbczyk
    • Mateusz Ficek
    • Jacek Ryl
    • Dongsheng Geng
    • Robert Bogdanowicz
    2022 Full text ADVANCED FUNCTIONAL MATERIALS

    Carbon (sp3)-on-carbon (sp2) materials have the potential to revolutionize fields such as energy storage and microelectronics. However, the rational engineering and printing of carbon-on-carbon materials on flexible substrates remains a challenge in wearable electronics technology. This study demon-strates the scalable fabrication of flexible laser-induced graphene (LIG)-boron doped diamond nanowall (BDNW) hybrid nanostructures for microsuperca-pacitors. Direct laser writing on polyimide film is tuned by the presence of BDNW powder where an appreciable absorbance of the BDNWs at the CO2laser wavelength enhances the local film temperature. The thermal shock due to laser irradiation produces graphitized and amorphous carbon at the diamond grain boundaries which increases the thermal and charge transfer capacity between the LIG–diamond interfaces. The samples are further treated with O2 plasma to tune the wettability or to improve the microsu-percapacitor device performance. The outstanding electrical characteristics of graphene, exceptional electrochemical stability of diamond, and essential contributions of oxygen-containing groups result in a remarkable charge storage capacity (18 mF cm−2 @ 10 mV s−1) and cyclic stability (98% retention after 10 000 cycles) outperforming most state-of-the-art LIG-based superca-pacitors. Furthermore, despite extreme mechanical stress, these microsu-percapacitors maintain their outstanding electrochemical properties, thus holding promise for high-power, flexible/wearable electronics.

  • Tuning the photocatalytic performance through magnetization in Co-Zn ferrite nanoparticles
    • Laura Cervera-Gabalda
    • Anna Zielińska-Jurek
    • Cristina Gómez-Polo
    2022 Full text JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

    In this work, the link between the photocatalytic performance of Co-Zn ferrite nanoparticles and the net magnetic moment is analyzed. CoxZn1-xFe2O4 nanoparticles (0 ≤ x ≤ 1) were synthesized by co-precipitation method and different physicochemical techniques were employed to characterize the samples (X-ray diffraction, Transmission Electron Microscopy (TEM), BET surface area, Diffuse Reflectance Spectroscopy (DRS), Photoluminescence spectroscopy, Z-potential, SQUID magnetometry). Enhanced photocatalytic degradation (maximum degradation ratios of two emerging pollutants, phenol and toluene) are found in those nanoparticles (0.4 ≤ x ≤ 0.6) with optimum magnetic response (i.e. superparamagnetism at room temperature and high saturation magnetization). The magnetization of the nanoparticles turns out to be the determining factor in the optimization of the photocatalytic response, since there is no clear relationship with other physicochemical parameters (i.e. specific surface area, isoelectric point, band gap energy or photoluminescence). These results support the current field of research related to photocatalytic performance enhancement through magnetic field effects.

  • Turbina wiatrowa jako element systemu radiolokalizacyjnego
    • Jacek Stefański
    • Jarosław Sadowski
    2022 Full text

    W referacie zaproponowano wykorzystanie turbiny wiatrowej do umieszczenia elementów systemu radiolokalizacyjnego do określania położenia obiektów latających. Zaproponowane rozwiązanie umożliwia osza-cowanie położenia obiektu w przestrzeni, zwłaszcza w ruchu, za pomocą sygnałów lokalizacyjnych nadawanych jednocześnie z wybranych punktów konstrukcyjnych turbiny. Przedstawiono matematyczną analizę metody oraz algorytm Chana (CA) do rozwiązywania układu nieliniowych równań pozycyjnych. W dalszej kolejności przedstawiono analizę parametru rozmycia położenia (PDoP) dla zaproponowanej metody. Na koniec zaprezentowano wyniki badań symulacyjnych dotyczących efektywności estymacji położenia obiektów dla tej metody dla wybranych parametrów systemowych.

  • Two-photon perimetry utilizing picosecond laser
    • Marcin Marzejon
    2022 Full text

    Age-related impairments are becoming more and more severe for aging societies. The sensory organ diseases are particularly troublesome as they exclude seniors from their everyday activity. Therefore, maintaining good quality eyesight is essential for normal functioning. New medical therapies help restrain age-related changes, but still, monitoring is essential to the treatment process. Humans do not have the natural ability to see infrared radiation, but they can see ultra-short nearinfrared laser pulses. The visual system reacts as if one photon of visible radiation has been absorbed, instead of two photons of infrared radiation have been absorbed in the photoreceptors. Further research on the two-photon vision assumes the development of a new diagnostic method – the two-photon perimetry. The two-photon perimetry is a new tool for the investigation of the near-infrared perception of the human eye. Before the method will be introduced to ophthalmic clinics, it is important to understand its physical and technical limitations. Therefore, the measurement setup and software have been developed, and tests on volunteers and patients have been performed. All system modalities: eye stimulation, pupil imaging, and the patient interface were made from scratch. The obtained results will help to find optimal solutions applicable to clinical practice.

  • Tworzenie wartości wspólnej w uniwersytecie. Perspektywa trójkąta wiedzy
    • Elżbieta Karwowska
    2022

    Społeczną odpowiedzialność uniwersytetu definiuje się jako dobrowolne działania uczelni, wykraczające poza obowiązek kształcenia i prowadzenia badań, których celem jest poprawa jakości życia ogółu. Mimo że trójczłonowość misji uniwersytetu może sugerować, że jest on społecznie odpowiedzialny „z natury”, wyniki badań pokazują, że społeczna odpowiedzialność nie jest fundamentem, z którego wynikają działania uniwersytetu, lecz raczej dodatkowym elementem jego działalności. USR często jest traktowana przedmiotowo i bagatelizowana, co utrudnia jej rozwój. Jednocześnie otoczenie społeczne postrzega uniwersytet jako inkubator wiedzy i technologii oraz oczekuje, że przyczynią się one do rozwiązania ważnych problemów, takich jak: globalne ocieplenie, zubożenie i rozwarstwienie społeczne, migracje, starzenie się populacji i choroby cywilizacyjne. Uczelnie powinny rozwijać swoją działalność, tak aby sprostać oczekiwaniom i potrzebom swoich interesariuszy oraz zacieśniać współpracę z coraz bardziej zróżnicowanymi grupami reprezentującymi społeczeństwo. Zaadaptowanie CSV do potrzeb i realiów funkcjonowania uniwersytetu może być kolejnym etapem ewolucji obu omawianych powyżej koncepcji. Może też stanowić odpowiedź na wyzwania, z jakimi mierzy się współczesny uniwersytet – zarówno związane z pogłębiającymi się problemami cywilizacyjnymi i środowiskowymi, zwiększającą się świadomością społeczną oraz oczekiwaniami względem zaangażowania uczelni, jak i wynikające z globalnej konkurencji o studentów i środki finansowe, niezbędne uczelni do rozwoju. Monografia składa się z sześciu rozdziałów. Trzy pierwsze poświęcono analizie literatury dotyczącej społecznej odpowiedzialności organizacji (rozdział 1), tworzenia wartości wspólnej (rozdział 2) oraz społecznej odpowiedzialności uniwersytetu (rozdział 3). Metodyka badania empirycznego została opisana w rozdziale 4, a jego wyniki omówiono w rozdziale 5. Rozdział 6 poświęcono natomiast przedstawieniu rekomendacji opracowanych na podstawie badania.

  • Two-Stage Variable-Fidelity Modeling of Antennas with Domain Confinement
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    • Łukasz Gołuński
    2022 Full text Scientific Reports

    Surrogate modeling has become the method of choice in solving an increasing number of antenna design tasks, especially those involving expensive full-wave electromagnetic (EM) simulations. Notwithstanding, the curse of dimensionality considerably affects conventional metamodeling methods, and their capability to efficiently handle nonlinear antenna characteristics over broad ranges of the system parameters is limited. Performance-driven (or constrained) modeling frameworks may be employed to mitigate these issues by considering a construction of surrogates from the standpoint of the antenna performance figures rather than directly geometry parameters. This permits a significant reduction of the model setup cost without restricting its design utility. This paper proposes a novel modeling framework, which capitalizes on the domain confinement concepts, and also incorporates variable-fidelity EM simulations, both at the surrogate domain definition stage, and when rendering the final surrogate. The latter employs co-kriging as a method of blending simulation data of different fidelities. The presented approach has been validated using three microstrip antennas, and demonstrated to yield reliable models at remarkably low CPU costs, as compared to both conventional and performance-driven modeling procedures.

  • Tyre/road noise measurements on ISO tracks according to the UNECE Regulation 117
    • Truls Berge
    • Piotr Mioduszewski
    2022

    Within the Polish-Norwegian research project ELANORE, a limited Round Robin Test has been performed on 3 ISO tracks in Northern Europe. The basic objective of the project is to improve the EU directive on labelling of tyres for noise and rolling resistance, and this directive is based on the measurement procedures defined in the UN ECE Reg.117. The same test car, test tyres and measurement equipment as well as personnel were used on all test tracks, to minimize the measurement uncertainties. All tracks were built according to the specification given in ISO 10844:2014. Five sets of C1 tyres were tested. They consisted of 2 sets of summer tyres, one all-season, one winter and one set of the SRTT tyres. Except for the SRTT tyres, the other 4 had labelled noise values from 67 to 74 dB. In addition to the test conditions specified in Reg.117, a modified test was also included, where the load and inflation pressure were adjusted to fit better the test vehicle specifications. Due to some adverse weather conditions at two of the test tracks, only a part of the test program was accomplished. The paper presents results from these measurements. Additional measurements are planned for 2022.

  • Tyre/road noise measurements on ISO tracks using the modified CPX method
    • Piotr Mioduszewski
    • Truls Berge
    2022

    Tyre rolling noise test method specified in the UNECE Regulation 117 is directly used in the Tyre Labelling Directive. Noise level specified on EU Tyre Label of each new tyre available on the European market was determined based on vehicle coast-by noise measurements performed on the standard reference road surface proscribed in the ISO 10844:2014. Available data from investigations by the vehicle and tyre industry and results from the STEER project show that the effect of ISO test track is significant. To estimate the noise variation on existing ISO test tracks, a small Round Robin Test was conducted on 3 of them, as a part of the joint Polish-Norwegian project ELANORE. The modified CPX method was used for this purpose. Measurements were performed for 9 selected tyres of summer, winter and all-season type, with label noise values ranging from 66 to 74 dB. Additionally, 2 standard reference tyres, P1 (SRTT) and H1 (Avon AV4), specified in the ISO 11819-3:2017 were tested. The obtained differences in noise levels for the tested tyres were up to 3.7 dB depending on test track. The ranking of tyres regarding measured noise levels didn’t correspond at all to the noise values given on tyre labels.

  • Układ sterowania 5-fazową maszyną synchroniczną z magnesami trwałymi (PMSM)
    • Krzysztof Łuksza
    • Jarosław Guziński
    • Marcin Morawiec
    • Filip Wilczyński
    2022 Automatyka Elektryka Zakłócenia

    W pracy przedstawiono nowy układ sterowania bezczujnikowego 5-fazową maszyną synchroniczną z magnesami trwałymi zagłębionymi (IPMSM) . Zaproponowany układ wykorzystuje obserwator stanu dla zmiennych w pierwszym układzie współrzędnych (1 harmoniczna), jak i drugim (3 harmoniczna), w celu zwiększenia gęstości momentu elektromagnetycznego. Zaprezentowano schemat kompletnego układu sterowania, przebiegi zmiennych w stanie ustalonym, jak również podczas stanów przejściowych, zarejestrowane podczas badań laboratoryjnych z wykorzystaniem prototypowej 5-fazowej maszyny PMSM.

  • Ultrasound-assisted deep eutectic solvent-based liquid–liquid microextraction for simultaneous determination of Ni (II) and Zn (II) in food samples
    • Fazal Elahi
    • Muhammad Balal Arain
    • Wajid Ali Khan
    • Hameed Haq
    • Asif Khan
    • Faheem Jan
    • Roberto Castro-Muñoz
    • Grzegorz Boczkaj
    2022 Full text FOOD CHEMISTRY

    A new approach was developed for the simultaneous pre-concentration and determination of Ni (II) and Zn (II) in food samples. This method is based on ultrasound-assisted liquid–liquid micro extraction using hydrophobic deep eutectic solvent (DES) and 1,10-phenanthroline as chelating agent. The effect of several parameters, such as pH, selection and volume of DES, amount of chelating agent, time of sonication and centrifugation, was studied. Under optimized conditions, the developed procedure offered exceptional sensitivity and linearity. The limit of detection was approximately 0.029 µg/Kg and 1.5 µg/Kg for Ni (II) and Zn (II), respectively. The proposed method was applied for the pre-concentration and determination of Ni (II) and Zn (II) in hydrogenated edible oils, fishes, and milk samples. The results of this study were compared with reported methods in the literature revealing its advantages.

  • Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Using Deep Eutectic Solvents (DESs) for Neutral Red Dye Spectrophotometric Determination
    • Sana Ullah
    • Hameed Haq
    • Muhammad Salman
    • Faheem Jan
    • Faisal Safi
    • Muhammad Balal Arain
    • Muhammad Khan
    • Roberto Castro-Muñoz
    • Grzegorz Boczkaj
    2022 Full text MOLECULES

    Deep eutectic solvents (DES), which have low toxicity and are low cost, biodegradable, and easily synthesized, were used for the extraction of neutral red (NR) dye before its spectrophotometric analysis. DES, containing choline chloride as a hydrogen bond acceptor and phenol as a hydrogen bond donor with a molar ratio of 1:2, was used for the extraction of NR dye from aqueous media. The possible interaction of different DESs with NR was studied using density functional theory (DFT) calculations. Experimentally, a UV-visible spectrophotometer was used for the quantitative analysis. The most important parameters affecting method performance, such as pH, extraction temperature, DES type, its volume, THF volume, sonication time, and centrifugation time, were optimized. The developed method provides exceptional sensitivity in terms of LOD and LOQ, which were 2.2 and 7.3 µg/L respectively. The relative standard deviation was 1.35–1.5% (n = 10), and the pre-concentration factor was 40. The method was found to be linear in the range of 2–300 µg/L (R2 = 0.9967). The method was successfully used for the determination of NR in wastewater samples. Finally, the DES-based method presents operational simplicity, high sensitivity, and rapid determination (<5 min) compared with other analytical procedures.

  • Uncertainty quantification of modal parameter estimates obtained from subspace identification: An experimental validation on a laboratory test of a large-scale wind turbine blade
    • Szymon Greś
    • Riccardo Riva
    • Cem Yeniceli Süleyman
    • Palle Andersen
    • Marcin Łuczak
    2022 Full text ENGINEERING STRUCTURES

    The uncertainty afflicting modal parameter estimates stems from e.g., the finite data length, unknown, or partly measured inputs and the choice of the identification algorithm. Quantification of the related errors with the statistical Delta method is a recent tool, useful in many modern modal analysis applications e.g., damage diagnosis, reliability analysis, model calibration. In this paper, the Delta method-based uncertainty quantification methodology is validated for obtaining the uncertainty of the modal parameter and the modal indicator estimates in the context of several well-known subspace identification algorithms. The focus of this study is to validate the quality of each Delta method-based approximation with respect to the experimental Monte Carlo distributions of parameter estimates using a statistical distance measure. On top of that, the accuracy in obtaining the related confidence intervals is empirically assessed. The case study is based on data obtained from an extensive experimental campaign of a large scale wind turbine blade tested in a laboratory environment. The results confirm that the Delta method is, on average, adequate to characterize the distribution of the considered estimates solely based on the quantities obtained from one data set, validating the use of this statistical framework for uncertainty quantification in practice.

  • Unconventional and user-friendly sampling techniques of semi-volatile organic compounds present in an indoor environment: An approach to human exposure assessment
    • Mariusz Marć
    • Bożena Zabiegała
    2022 Full text TRAC-TRENDS IN ANALYTICAL CHEMISTRY

    The commonly applied solutions used to assess the potential risk of human exposure to semi-volatile organic compounds (SVOCs) are based on the investigation of biological samples collected in an invasive or non-invasive manner. For SVOCs, which are typically introduced to humans through the respiratory system, dermal adsorption, or digestive system, sampling solutions generally used in the indoor environments are classified as active and passive. From the user's perspective, the most convenient method to assess the potential risk is the use of an analytical tool that combines the benefits of passive and non-invasive sampling techniques—use of an unconventional personal sampler such as a silicone wristband, brooch, dog tag, cotton gauze, or viscose wiper. Despite the advantages of this method, the aforementioned techniques require further analytical research owing to the differences in the results of human exposure assessment owing to the lack of standards and unified sampling protocols.

  • Uncovering the invisible barriers to women’s success
    • Agnieszka Lendzion
    2022

    In the area of science and higher education, as in business and politics, the job situation of women is improving, and the percentage of women on executive positions is increasing. However, there is still a serious underrepresentation of women in the highest decision-making bodies. Ladies also take part in the strategic institutional events less frequently. There are still serious disproportions in academic and management positions, and the research career of women in relation to men slows down and encounters various barriers. Universities and research institutions undertake various bottom-up and top-down, voluntary and forced gender equality initiatives. Nevertheless, women still face the phenomena of the glass ceiling, glass escalator, discrimination, violent behavior, income inequality and other barriers on their career paths. What makes barriers and stereotypes still present in a well-educated, aware academic and research environment? What can we do to overcome these problems? How to introduce changes effectively so that women climb (not only the scientific) career levels with a similar and the same impetus as men, so that research teams and decision-making bodies become diverse? During the discussion panel dedicated to uncover the invisible barriers to women’s success, we will try to answer these questions, share good practices and discuss potential solutions supporting women in academic environment.

  • Understanding ion–ion and ion–solvent interactions in aqueous solutions of morpholinium ionic liquids with N-acetyl-L-alaninate anion through partial molar properties and molecular dynamics simulations
    • Dorota Warmińska
    • Maciej Śmiechowski
    2022 JOURNAL OF MOLECULAR LIQUIDS

    Amino acid ionic liquids (AAILs) provide a low toxicity, biodegradable alternative to conventional ionic liquids, while also maintaining solubility in water. Densities and sound velocities of aqueous solutions of four amino acid ionic liquids (AAILs), based on the N-alkyl-N-methylmorpholinium ([Mor1,R], R = 2, 3, 6, 8) cation and N-acetyl-L-alaninate ([N-Ac-L-Ala]) anion were measured at T = (293.15–313.15) K and at atmospheric pressure. These data were used to derive the apparent molar volumes and the apparent molar compressibilities in the concentration range of (0.02–0.3) mol kg−1. Established extrapolation procedures were applied to estimate the values of the limiting apparent molar volumes and the limiting apparent molar compressibilities. The limiting apparent molar expansibility coefficients were obtained and the hydration numbers for AAILs in aqueous solution were calculated using Passynski’s method. The results indicate that ion–solvent interactions in the studied solutions are determined by the hydrophobic effect and the charge effect, which are both dependent on temperature. At low temperatures the ion–solvent interactions are determined by the hydrophobic effect which results in the decrease of the limiting apparent molar compressibilities with an elongation of the alkyl chain of the cation of AAIL. At high temperatures the charge effect is dominant due to the decreasing limiting apparent molar compressibilities. On the other hand, ion–ion interactions are dominated by the hydrophobic effect regardless of the temperature. Molecular dynamics simulations were also performed and applied in interpretation of experimental data at atomistic detail. Computed limiting apparent molar volumes correlate well with the values derived from experiment. The apparent hydration volume, obtained by subtracting the intrinsic volume contribution, is large and positive, indicating hydrophobic hydration and not electrostriction is the principal mode of ions’ influence on the solvent. Analysis of radial distribution functions confirms insignificant share of ion–ion interactions via contact ion pairing. The solvation shells signify predominantly hydrophobic hydration, with locally strongly hydrated functional groups.

  • Understanding the early-stage release of volatile organic compounds from rapeseed oil during deep-frying of tubers by targeted and omics-inspired approaches using PTR-MS and gas chromatography
    • Tomasz Majchrzak
    • Mariusz Marć
    • Andrzej Wasik
    2022 Full text FOOD RESEARCH INTERNATIONAL

    During deep-frying, a plethora of volatile products is emitted with the fumes. These compounds could act as oil quality indicators and change the indoor air composition leading to health risks for occupants. The presented experiments focus on deep-frying of different tubers in rapeseed oil at different frying temperatures. Here, two scenarios for real-time monitoring of volatile organic compounds (VOCs) using proton transfer reaction mass spectrometry (PTR-MS) were proposed. The first, targeted, involved the application of gas chromatography with a flame ionization detector (GC-FID). The second, omics-inspired, involved the use of solid-phase microextraction (SPME) along with gas chromatography-mass spectrometry (GC-MS) and molecular networking algorithm as a complementary tool to the PTR-MS analysis. In a targeted approach, it was shown that the emission profile of pentanal and hexanal depends on the frying temperature and as the temperature increases, a sudden release of these compounds can be observed in the first minutes of frying. Meanwhile, using an omics-inspired protocol enables finding the relation between 1,4-heptadienal and 2-heptanone, octanal and limonene emissions. Using both approaches it was possible to record real-time changes in emission profiles of various oils’ degradation products. It was also observed that the emission profiles of VOCs are strictly related to the frying temperature and the type of fried tuber.

  • Understanding the Electronic Structure and Optical Properties of Vacancy-Ordered Double Perovskite A2BX6 for Optoelectronic Applications
    • Muhammad Faizan
    • Xinjiang Wang
    • Shaimaa A. M. Abdelmohsen
    • K. C. Bhamu
    • Subrahmanyam Sappati
    • Amel Laref
    • Nisar Muhammad
    • Muhammad Mushtaq
    • Ashraf M. M. Abdelbacki
    • Rabah Khenata
    2022 Full text ENERGY & FUELS

    Over the past few years, metal halide perovskite solar cells have made significant advances. Currently, the single-junction perovskite solar cells reach a conversion efficiency of 25.7%. Perovskite solar cells with a wide band gap can also be used as top absorber layers in multi-junction tandem solar cells. We examined the dynamical and thermal stability, electronic structure, and optical features of In2PtX 6 (X = Cl, Br, and I) perovskites, utilizing first-principle calculations. The stability is predicted using phonon dispersion spectrum and ab initio molecular dynamics simulation and also through the convex hull approach. The lattice constants and the optimized volume show an increasing trend with changing halide ions. The band structures computed for In2 PtCl6, In 2PtBr 6, and In2 PtI6 indicate their semiconducting nature with band gap values of 2.06, 2.01, and 1.35 eV, respectively. Halogens p and Pt d orbitals, respectively, play a prominent role in the formation of states around valence band maximum and conduction band minimum. The compounds, namely, In2PtBr 6 and In2PtI 6, exhibit high dielectric constants and small carrier effective masses. Furthermore, we found that In2 PtI 6 reveals a maximum theoretical efficiency owing to its optimum band gap and high optical absorption and is comparable to MAPbI3 in the studied range. Our results suggest that In 2PtX 6 (X = Cl, Br, and I) are suitable materials for single-junction and top absorber layers in tandem solar cells.

  • Underwater Processing of Materials
    • Dariusz Fydrych
    • Jacek Tomków
    2022 Full text Materials

    Editorial do SI

  • Underwater wet welding of S1300 ultra-high strength steel
    • Jacek Tomków
    • Michał Landowski
    • Dariusz Fydrych
    • Grzegorz Rogalski
    2022 Full text MARINE STRUCTURES

    Marine Structures Volume 81, January 2022, 103120 Underwater wet welding of S1300 ultra-high strength steel Author links open overlay panelJacekTomkówGrzegorzRogalski https://doi.org/10.1016/j.marstruc.2021.103120 Get rights and content Under a Creative Commons licenseopen access Highlights • Technological method of S1300 steel underwater weldability improving was proposed. • Number of cracks and hardness of welded joints was reduced by Temper Bead Welding (TBW). • Thickness of the base metal does not affect the effectiveness of the TBW technique. • The highest TBW effectiveness was found for 50% beads overlap. Abstract An expected tendency in marine and offshore structures is an increasing share of steels with high mechanical properties. The necessity to perform the welding work under water leads to a decreasing of the weldability of the steel. It results from the increased susceptibility to form cold cracks, especially in welded structures made of high-strength steel. A potential method, which may improve the problem of limited weldability of steel under water is the use of temper bead welding (TBW) technique. In this paper, the possibility of underwater wet welding by covered electrode S1300 ultra-high strength steel of different thickness (4 mm and 10 mm) has been investigated. The visual, metallographic macro- and microscopic tests, and Vickers HV10 measurements of samples with two nonparallel beads were performed. On the basis of the performed tests, the effectiveness of TBW technique was quantitatively verified. It was proved that TBW leads to positive microstructural changes and reduces the number of cracks in different regions of welded joints. Moreover, it was found that the proposed technique allows to decrease the hardness of S1300 steel joint by 30–80 HV10 in the weld metal and 40–100 HV10 in heat-affected zone. Finally, it was stated that the thickness of the base material does not affect the effectiveness of the TBW technique.

  • Universal construction of genuinely entangled subspaces of any size
    • Maciej Demianowicz
    2022 Full text Quantum Journal

    We put forward a simple construction of genuinely entangled subspaces – subspaces supporting only genuinely multipartite entangled states – of any permissible dimensionality for any number of parties and local dimensions. The method uses nonorthogonal product bases, which are built from totally nonsingular matrices with a certain structure. We give an explicit basis for the constructed subspaces. An immediate consequence of our result is the possibility of constructing in the general multiparty scenario genuinely multiparty entangled mixed states with ranks up to the maximal dimension of a genuinely entangled subspace.

  • Unusual divergence of magnetoacoustic beams
    • Anna Perelomova
    2022 Full text PHYSICS OF PLASMAS

    Two-dimensional magnetosonic beams directed along a line forming a constant angle h with the equilibrium straight magnetic field are considered. Perturbations in a plasma are described by the system of ideal magnetohydrodynamic equations. The dynamics of perturbations in a beam are different in the cases of fast and slow modes, and it is determined by h and equilibrium parameters of a plasma. In particular, a beam divergence may be unusual in the case of parallel propagation (h ¼ 0). Diffraction is more pronounced in the case of parallel propagation as compared to a flow without magnetic field, and less manifested in the case of perpendicular propagation. The beams propagating oblique to the magnetic field do not reveal diffraction. The dynamics of perturbations in a beam are analytically described in the cases of weak and strong nonlinearity compared to diffraction. Small magnitude perturbations at the axis of a beam in unusual cases propagate slower than that in the plane wave. Involving of thermal conduction leads to the coupling equations describing thermal self-action of a beam, which behaves differently in the ordinary and unusual cases. Self-focusing may occur in the presence of a magnetic field instead of conventional defocusing in gases

  • Up-to-date strategies and future trends towards the extraction and purification of Capsaicin: A comprehensive review
    • Roberto Castro-Muñoz
    • Emilia Gontarek-Castro
    • Seid Mahdi Jafari
    2022 Full text TRENDS IN FOOD SCIENCE & TECHNOLOGY

    Background According to the current need of manufacturing healthier products, food companies are seeking specific biomolecules that may offer additional added value (i.e., biological activities) to the new food formulations. Capsaicin, as the pungent ingredient of chili peppers, has become so far one of the target biomolecules explored since the 1950s. There is evidence demonstrating that capsaicin exhibits important biological properties in human health including inhibits acid secretion, stimulates alkali and mucus secretion and particularly gastric mucosal blood flow contributing to the prevention and healing of gastric ulcers, thermoregulation, among many other reported bioactivities. Scope and approach However, one of the main bottlenecks deals with the proper protocol of extraction and purification of this compound since most of the conventional methods based on solvent extraction do not provide efficient yield, along with diminished bioactivity of the compounds. Therefore, this review comprehensively elucidates the current strategies proposed by researchers towards the sustainable extraction and purification of capsaicin from its natural source, and comparison over traditional extraction methods. Particular emphasis has been focused on the innovative extraction techniques and the relevant insights over the last five years. Key findings and conclusion A detailed discussion is provided on the advantages and drawbacks of the novel techniques, key interactions with target molecules and their effect on the bioactivity of capsaicin. To finalize, according to the findings of this review, the future trends, perspectives, and research gaps are also given.

  • Urinary Tract Infections Caused by K. pneumoniae in Kidney Transplant Recipients – Epidemiology, Virulence and Antibiotic Resistance
    • Beata Krawczyk
    • Magdalena Wysocka
    • Michał Michalik
    • Justyna Gołębiewska
    2022 Full text FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY

    Urinary tract infections are the most common complication in kidney transplant recipients, possibly resulting in the deterioration of a long-term kidney allograft function and an increased risk of recipient’s death. K. pneumoniae has emerged as one of the most prevalent etiologic agents in the context of recurrent urinary tract infections, especially with multidrug resistant strains. This paper discusses the epidemiology and risk factors associated with urinary tract infections in kidney transplant recipients, multi-drug resistance of K. pneumoniae (ESBL, KPC, NDM), treatment and pathogenesis of K. pneumoniae infections, and possible causes of recurrent UTIs. It also addresses the issue of colonization/becoming a carrier of K. pneumoniae in the gastrointestinal tract and asymptomatic bacteriuria in relation to a symptomatic UTI development and epidemiology.

  • Use of a wastewater recovery product (struvite) to enhance subtropical seagrass restoration
    • Conor Macdonnell
    • Franciszek Bydałek
    • T. Z. Osborne
    • A. Beard
    • S. Barbour
    • D. Leonard
    • Jacek Mąkinia
    • P.w. Inglett
    2022 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    Seagrasses are in decline worldwide, and their restoration is relatively expensive and unsuccessful compared to other coastal systems. Fertilization can improve seagrass growth in restoration but can also release nutrients and pollute the surrounding ecosystem. A slow-release fertilizer may reduce excessive nutrient discharge while still providing resources to the seagrass's rhizosphere. In this study, struvite (magnesium ammonium phosphate), a relatively insoluble, sustainable compound harvested in wastewater treatment plants, was compared to Osmocote™ (14:14:14 Nitrogen: Phosphorus: Potassium, N:P:K), a popular polymer coated controlled release fertilizer commonly used in seagrass restoration. Two experiments compared the effectiveness of both fertilizers in a subtropical flow-through mesocosm setup. In the first experiment, single 0.5 mg of P per g dry weight (DW) doses of Osmocote™ and struvite fertilizers were added to seagrass plots. Seagrass shoot counts were significantly higher in plots fertilized with struvite than both the Osmocote™ and unfertilized controls (p < 0.0001). A significant difference in total P concentrations was observed in porewater samples of Osmocote™ vs struvite and controls (p < 0.0001), with struvite fertilized plots emitting more than controls (p ≤ 0.0001), but less than 2% of the total dissolved P (TDP) of Osmocote™ fertilized plots (100+ mg/L versus x > 5 mg/L). A subsequent experiment, using smaller doses (0.01 and 0.025 mg of P per gram DW added), also found that the struvite treatments performed better than Osmocote™, with 16–114% more aboveground biomass (10–60% higher total biomass) while releasing less N and P. These results indicate the relatively rapid dissolution of Osmocote™ may pose problems to restoration efforts, especially in concentrated doses and possibly leading to seagrass stress. In contrast, struvite may function as a slow-release fertilizer applicable in seagrass and other coastal restoration efforts.

  • Use of structural equation modeling in quantitative research in the field of management and economics: A bibliometric analysis in the systematic literature review
    • Agnieszka Zakrzewska-Bielawska
    • Anna Lis
    • Anna Ujwary-Gil
    2022 Full text Journal of Entrepreneurship, Management and Innovation

    PURPOSE: This paper aims to provide a comprehensive review of scholarly research focusing on using quantitative methods and particularly structural equation modeling (SEM) in management and economics studies, as well as provide a bibliometric agenda including the time horizon of individual publications, the highest citation rate, geographic and industry areas, methodological context, and keywords. METHODOLOGY: A systematic literature review (SLR) was undertaken using the Web of Science and Scopus databases. We limited our search to the last five years to identify the newest research publications, and we used keywords related to quantitative research while excluding qualitative research. Then we analyzed papers related to SEM and those published in English. FINDINGS: Our results confirmed that quantitative methods are used both in management and economics research, and showed a growing trend in the number of publications in the last five years. However, there are many more publications on management than on economics as well as there are more papers published in the Scopus database than Web of Science. Taking into account structural equation modeling, this method is used primarily in management research. In terms of industry, publications using SEM considered both single- and multi-industry including, first, all Asian countries and then African ones. Publications, especially in the management field, are descriptive in nature and based on primary data collected using a survey questionnaire. Papers are published in various journals and the most cited are those published in journals with wider subject areas. IMPLICATIONS: The systematic literature review is a fundamental necessity in any field of knowledge, benefiting both academia and learners. Our results may be useful for future researchers planning research using quantitative methods, especially SEM, in the business or economic field, by indicating the most cited papers and journals as well as industry and country areas. ORIGINALITY AND VALUE: This paper represents a systematic attempt to link quantitative methods, with a particular emphasis on SEM, with research interests on managerial and economic subjects and papers published in the Web of Science and Scopus databases. Employing the bibliometric analysis within the systematic literature review, the paper shows interest and the current state of research using quantitative methods which proves its value and originality.

  • User Mobility’s Influence on System Loss in Off-Body BAN Scenarios
    • Manuel M. Ferreira
    • Filipe D. Cardoso
    • Luis M. Correia
    • Sławomir Ambroziak
    • Kenan Turbić
    2022

    In this paper, a measurement campaign for off-body communications in an indoor environment is investigated for a set of on-body antennas. The channel impulse response was measured with the user approaching and departing from an off-body fixed antenna using two user dynamics: standing at fixed positions and walking. The processing of the measurement data allowed to evaluate system loss statistics. Different antenna configurations are classified in terms of mobility and visibility depending on on-body antenna placements. A dependence on distance is found for the antennas with the lowest mobility (chest and head), while no significant dependence is found for the antennas with highest mobility (arm and leg). Regarding the standard deviation for system loss, higher values are found in the walking scenarios (above 2.6 dB) compared to the standing ones (below 0.6 dB). Standard deviation also shows a clear dependence on mobility: 1.6 dB for walking and 0.5 dB for standing scenarios.

  • User-assisted methodology targeted for building structure interpretable QSPR models for boosting CO2 capture with ionic liquids
    • Joachim Eichenlaub
    • Paulina Rakowska
    • Adam Kloskowski
    2022 JOURNAL OF MOLECULAR LIQUIDS

    Task-specific ionic liquid (IL) is an emerging class of compounds that may be environmentally friendly. Properly selected, these compounds may be green alternative to amine solutions and can replace them in post-combustion carbon dioxide (CO2) capture processes on an industrial scale. However, owing to the vast diversity of ions and their possible combinations, laboratory research is time consuming and expensive. Therefore, computational methods are preferred for assessing their potential applications. In this study, three quantitative structure–property relationship models based on six distinct descriptors were created to predict Henry’s law constant (HLC) of CO2 in 62 ILs. The statistical parameters of multiple linear regression, logistic regression, and partial least squares models were satisfactory. In all cases, the coefficients of determination (R2) exceeded 0,90, and both external and internal validation proved them to be reliable and predictive with Q2 and Rpred2 values exceeding 0,90 and 0,87, respectively. Three of the descriptors were attributed to cations, and three were attributed to anions. In contrast to many other models, the descriptors were chosen in a manner that ensured their interpretability. Each of the six descriptors was analyzed for its influence on HLC. On this basis, guidelines for designing the structure of ionic liquids with increased CO2 absorption capacity were developed.

  • Using Convolutional Neural Networks for Corneal Arcus Detection Towards Familial Hypercholesterolemia Screening
    • Tomasz Kocejko
    • Jacek Rumiński
    • Magdalena Mazur-Milecka
    • Marzena Romanowska-Kocejko
    • Krzysztof Chlebus
    • Jo Kang-Hyun
    2022 Full text Journal of King Saud University-Computer and Information Sciences

    Familial hypercholesterolemia (FH) is a highly undiagnosed disease. Among FH patients, the onset of premature coronary artery disease is 13 times higher than in the general population. Early diagnosis and treatment is essential to prevent cardiovascular diseases and their complications, and to prolong life. One of the clinical criteria of FH is the occurrence of a corneal arcus (CA) among patients, especially those under 45 years old. Therefore, by detecting a CA, it might be possible to reduce the number of undiagnosed FH cases. In this paper, we propose using convolutional neural networks (CNN) for automatic recognition of the presence of a corneal arcus. To achieve this goal, we created a dataset of images of irises containing different stages of CA as well as irises without a CA. The core of the dataset consists of images acquired from patients with a corneal arcus, enroled in the National Centre of Familial Hypercholesterolemia in Gdansk. To increase the number of images, the dataset was complemented with images downloaded from the Internet. This dataset created for training and testing the model consisted of nearly 4000 images. To detect a CA in photographic images, we tested neural network models based on the VGG16, ResNet and Inception architectures. Finally, the performance of the models was evaluated on a set of images acquired from volunteers with a custom mobile application. The accuracy of CA detection in a real life scenario was 88% and the F1 score was 86%

  • Using differential pressure sensor to measure nitrous oxide level in a tank
    • Mateusz Czapski
    • Wiktor Lachowski
    • Natalia Balogh
    • Wojciech Deszczyński
    • Krzysztof Hucik
    • Wiktor Sieklicki
    2022 Full text

    A method for measuring the level of liquid nitrous oxide oxidizer in a hybrid rocket motor oxidizer tank is proposed. Presented approach is more accurate than the most commonly used method of this measurement, which employs weighting of the whole sounding rocket or an oxidizer tank. In our solution we use a differential pressure sensor to measure the change of pressure at the bottom of an oxidizer tank in comparison to the pressure of the gas phase above the liquid. Due to usage of a relatively short oxidizer tank, with height of 900 mm, and density of nitrous oxide being smaller than water, at 786.6 kg m3 , measured pressure differences are small, which requires high resolution of the sensor. Our system was prepared to work in a hybrid rocket motor of SimLE student organisation from Gdansk University of Technology (Gdansk, Poland). Developed propulsion system is designed to allow a sounding rocket with 4 kg of payload to accurately reach a flight altitude of 3000 m. The reason for accurate calculation of oxidizer amount in a tank is precise altitude planning for a sounding rocket launch which does not employ any active aerobraking system. For this flight strategy, accurate measurement of engine parameters is crucial. The described system is theoretically able to measure liquid level with a 5 mm resolution, which corresponds to roughly 50 g of nitrous oxide in the tank. Other approach, using a load cell, showed measurement resolution of 100 g of weight difference. This method was susceptible to hysteresis due to friction and other external conditions on a launch rail. Preliminary results from hybrid rocket engine tests are presented along with perspective for further method improvement.

  • Using Disparity Map for Moving Object Position Estimation in Pan Tilt Camera Images
    • Tomasz Kocejko
    • Jacek Rumiński
    • Jo Kang-Hyun
    2022

    In this paper we present the algorithm for rapid moving object position estimation in an images acquired from pan tilt camera. Detection of a moving object in a image acquired from a moving camera might be quite challenging. Standard methods that relay on analyzing two consecutive frames are not applicable due to the changing background. To overtake this problem we decided to evaluate the possibility of calculating a disparity map based on this consecutive images. As a result we were able to obtain approximate position of moving object in real time. Using cpu the average detection time was below 0.17 second.

  • Using Long-Short term Memory networks with Genetic Algorithm to predict engine condition
    • Semra Erpolat Tasabat
    • Olgun Aydin
    2022 Gazi University Journal of Science

    Predictive maintenance (PdM) is a type of approach for maintenance processes, allowing maintenance actions to be managed depending on the machine's current condition. Maintenance is therefore carried out before failures occur. The approach doesn’t only help avoid abrupt failures but also helps lower maintenance cost and provides possibilities to manufacturers to manage maintenance budgets in a more efficient way. A new deep neural network (DNN) architecture proposed in this study intends to bring a different approach to the predictive maintenance domain. There is an input layer in this architecture, a Long-Short term memory (LSTM) layer, a dropout layer (DO) followed by an LSTM layer, a hidden layer, and an output layer. The number of epochs used in the architecture and the batch size was determined using the Genetic Algorithm (GA). The activation function used after the output layer, DO ratio, and optimization algorithm optimizes loss function determined by using grid search (GS). This approach brings a different perspective to the literature for finding optimum parameters of LSTM. The neural network and hyperparameter optimization approach proposed in this study performs much better than existent studies regarding LSTM network usage for predictive maintenance purposes

  • Using Minimum Actuators to Control Shape and Stress of a Double Layer Spherical Model Under Gravity and Lateral Loadings
    • Najmadeen Saeed
    • Javad Katebi
    • Ahmed Manguri
    • Aram Mahmood
    • Marcin Szczepanski
    • Robert Jankowski
    2022 Full text Advances in Science and Technology Research Journal

    Spherical domes are picturesque structures built in developed countries to attract tourists. Due to horizontal and vertical overloading, the structures’ attractive shapes may be disturbed, and some members' stress may exceed the elastic level. In this paper, the shape and stress of a deformed double-layer spherical numerical model due to simultaneous lateral and vertical loadings are controlled, meanwhile, the number of actuators to alter the length of active members is minimized. The nodal displacements of the outer shape of the numerical model of the double-layer spherical structure are nullified. In addition, the stress of the members of the structure was monitored to stay within the elastic level. Moreover, the number of used actuators was minimized. These objectives are done by subjecting controlling formulations to a function that finds the minimum of constrained nonlinear multivariable which is called fmincon. The defined function in MATLAB uses one of the optimization algorithms (sequential quadratic programming, interior point, trust-region reflective, and active set). The algorithms search for active members that have a significant influence in controlling the targeted joints and members. Furthermore, the algorithms exclude the inactive actuators in several loops. The results obtained from MATLAB program are validated by SAP2000 software.

  • Using Synchronously Registered Biosignals Dataset for Teaching Basics of Medical Data Analysis – Case Study
    • Tomasz Kocejko
    2022 Full text

    Medical data analysis and processing strongly relies on the data quality itself. The correct data registration allows many unnecessary steps in data processing to be avoided. Moreover, it takes a certain amount of experience to acquire data that can produce replicable results. Because consistency is crucial in the teaching process, students have access to pre-recorded real data without the necessity of using additional equipment for data acquisition. The analyzed sample dataset consists of raw signals of ECG, Body Impedance and Body temperature recorded synchronously in laboratory conditions. The data are sampled with 250Hz sampling frequency and are framed in blocks. Students gain a chance to acquire, exchange and process the medical data in simulated conditions. Pre-recording data provides the opportunity to teach certain techniques that can be used in real life scenarios but in a control replicable environment.

  • Validated GC–MS method for determination of bisphenol a and its five analogues in dietary and nutritional supplements
    • Katarzyna Owczarek
    • Emilia Waraksa
    • Ewa Kłodzińska
    • Yaroslav Zrobok
    • Mariusz Ozimek
    • Dominik Rachoń
    • Błażej Kudłak
    • Andrzej Wasik
    • Zofia Mazerska
    2022 MICROCHEMICAL JOURNAL

    Bisphenol A (BPA) and its analogues showing structural and functional similarity to BPA are commonly applied in various industrial applications and thus are becoming ubiquitous in the environment. At the same time there is increasing scientific evidence that exposure to these chemicals may lead to adverse health effects in human and wildlife. In recent years dietary and nutritional supplements dedicated for athletes have become more popular and are widely used even by people who are not professionals. This study presents the development, optimization and validation of an analytical procedure for determination of six bisphenol analogues in dietary supplements using gas chromatography – mass spectrometry technique. All validation parameters met the established acceptance criteria in accordance with international guidelines.

  • Validating the Rules of Government Automation
    • Elsa Estevez
    • Tomasz Janowski
    • David Benjamin Roseth
    2022

    There is growing evidence on the benefits and risks of government automation, and how should government organizations proceed with automation when the benefits outweigh the risks. This evidence was recently consolidated into the "rules of government automation", part of the project funded by the Inter-American Development Bank. The project uncovered that the combined nature of government work and its transformation into digital government create many opportunities for automation. However, such opportunities can be only realized when the right automation technology becomes available and when government organizations are willing, capable, and authorized to introduce it, considering the impact on the organization and its stakeholders and the balance of benefits and risks brought about by this impact. The aim of the workshop is to validate the above “rules of government automation”. To this end, the participants will bring to the workshop their own government automation cases, from practice or research, establish thorough inspection and guided reasoning whether the rules hold for their cases, refine them otherwise, and iteratively agree on the refined rules across all cases. The workshop will also initiate the planning of a special issue of Government Information Quarterly to advance the theory and practice of government automation.

  • VALUATION OF EMBEDDED OPTIONS IN NON-MARKETABLE CALLABLE BONDS: A NEW NUMERICAL APPROACH
    • Roman Skalický
    • Marek Zinecker
    • Adam P. Balcerzak
    • Michał Pietrzak
    • Elżbieta Rogalska
    2022 Full text Technological and Economic Development of Economy

    The issue of how to price options embedded in callable bonds has attracted a lot of interest over the years. The usual bond valuation methods rely on yield curves, risk premium, and other parameters to estimate interest rates used in discounted cash flow calculations. The option to retire the bond is, however, neglected in the standard pricing models, causing a systematic overvaluation of callable bonds. In the event of a decline in interest rates, investors are exposed to the risk of a lower return on investment than indicated by the yield to maturity. We propose a novel approach to valuing the risk that the issuer will use the right to buy back the bond at a specific call price. While prior models are focused on valuing marketable callable bonds, we deliver a unique approach to valuing bonds with an embedded European option (or a multiple option) that are traded solely through private transactions. These can typically be characterized by the lack of historical records on transaction prices. The modular character of calculation we propose allows us to take into account additional information, such as probable behaviour of the issuer, available opportunities for achieving alternative earnings or different estimates in terms of interest rate development.