Repozytorium publikacji - Politechnika Gdańska

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Repozytorium publikacji
Politechniki Gdańskiej

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  • Rezystancja uziemienia złącza kablowego SN
    • Stanisław Czapp
    2020 INPE: Informacje o Normach i Przepisach Elektrycznych

    Udzielono odpowiedzi na pytanie czytelnika nadesłane do redakcji czasopisma INPE. Wyjaśniono zasady wyznaczania rezystancji uziemienia stacji elektroenergetycznej zawierającej transformator SN/nn. Wskazano prawidłowy tok postępowania w przypadku złącza SN zawierającego transformator SN/nn małej mocy zasilający urządzenia niskiego napięcia wyłącznie w obrębie tego złącza.

  • Rheology of liquid crystalline polymers
    • Ewa Głowińska
    • Paulina Parcheta
    • Janusz Datta
    2020

    Liquid crystallinity was invented in the 19th century. It was sometimes called the fourth state of matter because of the ability of macromolecules to generate liquid crystal phases. The main classification divided liquid crystalline polymers (LCPs) into lyotropic and thermotropic types. Interpretation of the rheological behavior of LCP is more complicated than for other polymers. Ordinary polymers are characterized by a normal stress effect in shear flow, which always has a positive sign. There is a visible impact of temperature, solvents, plasticizers, the macromolecular structure, and the average molecular weight on the rheological behavior of LCPs. This chapter approximates and describes the most characteristic rheological behaviors of LCPs.

  • Rheology of polymer blends
    • Marcin Włoch
    • Janusz Datta
    2020

    Polymer blends are physical mixtures of two or more homopolymers or copolymers. This type of materials have wide spectrum of technological applications, and their properties are influenced, e.g., by the properties of single components and morphology of final material. The rheology of polymer blends is connected with the processing of polymer blends and is influenced by thermodynamics, morphology, and their evolution during testing. This chapter provides an overview of research areas in the field of miscible and immiscible polymer blend rheology. Selected issues were discussed, e.g., application of time-temperature superposition principle in miscible polymer blends (concerning influence of intra- and intermolecular hydrogen bonding), influence of rheometer geometry on the obtained results, multiphase flow (including behavior of droplets in matrix), and flow imposed morphologies.

  • Rigorous numerics for critical orbits in the quadratic family
    • A. Golmakani
    • C. E. Koudjinan
    • S. Luzzatto
    • Paweł Pilarczyk
    2020 Pełny tekst CHAOS

    We develop algorithms and techniques to compute rigorous bounds for finite pieces of orbits of the critical points, for intervals of parameter values, in the quadratic family of one-dimensional maps fa(x)=a−x2. We illustrate the effectiveness of our approach by constructing a dynamically defined partition P of the parameter interval Ω=[1.4,2] into almost 4 million subintervals, for each of which we compute to high precision the orbits of the critical points up to some time N and other dynamically relevant quantities, several of which can vary greatly, possibly spanning several orders of magnitude. We also subdivide P into a family P+ of intervals which we call stochastic intervals and a family P− of intervals which we call regular intervals. We numerically prove that each interval ω∈P+ has an escape time, which roughly means that some iterate of the critical point taken over all the parameters in ω has considerable width in the phase space. This suggests, in turn, that most parameters belonging to the intervals in P+ are stochastic and most parameters belonging to the intervals in P− are regular, thus the names. We prove that the intervals in P+ occupy almost 90% of the total measure of Ω. The software and the data is freely available at this http URL, and a web page is provided for carrying out the calculations. The ideas and procedures can be easily generalized to apply to other parametrized families of dynamical systems.

  • Risk of power cables insulation failure due to the thermal effect of solar radiation
    • Stanisław Czapp
    • Seweryn Szultka
    • Filip Ratkowski
    • Adam Tomaszewski
    2020 Pełny tekst Eksploatacja i Niezawodność - Maintenance and Reliability

    Low-voltage, as well as high-voltage power cable lines, are usually buried in the ground. The ampacity of the power cables in the ground mainly depends on the thermal resistivity of the soil, which may vary in a wide range. A common practice in power cable systems performance is to supply them from a pole of an overhead line. If so, a section of the line is located in free air and can be directly exposed to solar radiation. In some cases, the ampacity of power cables placed in free air is lower than in the ground. Differences in ampacities can be very high if thermal resistivity of the soil is very low, and simultaneously solar irradiation of cables in air occurs. This paper presents the risk of power cables overheating and in consequence the risk of their failure, when part of the underground power cable line is placed in free air. Temperature distribution of cables in the air (with and without solar radiation) for various load currents is presented. Thermal endurance of power cables insulation, operating with the overheating, is estimated.

  • RMS-based damage identification in adhesive joint between concrete beam and steel plate using ultrasonic guided waves
    • Erwin Wojtczak
    • Magdalena Rucka
    • Magdalena Knak
    2020

    Adhesive joints have numerous applications in many branches of industry, such as civil engineering, automotive, aerospace and shipbuilding. As with most structural elements, adhesive joints can experience any damage mechanism, which induces the need for diagnostic testing. Ultrasonic waves are widely used for non-destructive inspection of many structures and their elements, including adhesive joints. Guided wave propagation method consists in excitation of wave in one point of analysed element and collection of signals in a set of points spread over this element. Further signal processing, such as calculation of root mean square values (RMS), can provide a precise damage imaging, because of a high vulnerability of wave characteristics to any discontinuity. The work is focused on identification and localisation of damaged areas in adhesive film of steelclad concrete beams. Steel-concrete composite elements, such as steel-clad concrete beams containing adhesive joints are commonly used in civil infrastructure. In the conducted research, composite specimens were prepared with the use of an epoxy-based adhesive Sikadur® 30 Normal. Artificial defects were performed by omitting adhesive film on a part of a joint. The input wave signal was provided by the arbitrary function generator. Elastic waves were excited by plate piezoelectric actuator placed on a steel plate. Signals of propagating waves were collected point by point on the surface of steel part of the joint, by means of the scanning laser vibrometer. The maps representing RMS values calculated individually for each signal proved to be an effective visualisation of the actual shape and position of damage areas.

  • Robot Eye Perspective in Perceiving Facial Expressions in Interaction with Children with Autism
    • Agnieszka Landowska
    • Ben Robins
    2020 Advances in Intelligent Systems and Computing

    The paper concerns automatic facial expression analysis applied in a study of natural “in the wild” interaction between children with autism and a social robot. The paper reports a study that analyzed the recordings captured via a camera located in the eye of a robot. Children with autism exhibit a diverse level of deficits, including ones in social interaction and emotional expression. The aim of the study was to explore the possibility of applying automatic emotion recognition in analyzing human-robot interaction. The study revealed some challenges, that might be classified as activity-based, child conditionbased and setup-based ones. Despite those, the facial expressions in children with autism were on average more positive than in a control group of typically developing children. Children with autism seemed to enjoy the interaction with the robot more. The paper might be interesting for researchers and practitioners who plan to combine social robots and emotion recognition in children with autism.

  • Rodowód Katedry Energoelektroniki i Maszyn Elektrycznych Politechniki Gdańskiej z lat 1945-1969
    • Mieczysław Ronkowski
    • Piotr Chrzan
    2020 Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    Przedstawiono sylwetki pierwszych powojennych profesorów Wydziału Elektrycznego PG, którzy tworzyli zespoły naukowe i laboratoria do prowadzenia badań i nauczania konstrukcji maszyn elektrycznych, napędów elektrycznych, techniki cyfrowej i energoelektroniki. W wyniku ich działalności oraz przemian organizacyjnych Politechniki Gdańskiej powstała na Wydziale Elektrotechniki i Automatyki, Katedra Energoelektroniki i Maszyn Elektrycznych.

  • Rola architektury w energetyce budynku
    • Katarzyna Zielonko-Jung
    2020

    celem tego rozdziału jest wyodrębnienie i usystematyzowanie środków architektonicznych, których stosowanie może pozytywnie wpłynąć na procesy energetyczne zachodzące w budynkach. nazwano je energoaktywnymi rozwiązaniami architektonicznymi. Podzielono je na pięć grup, stosownie do zagadnień, w których się mieszczą, co odpowiada kolejnym etapom projektowania. zakres opracowania został ograniczony do decyzji pozostających w wyłącznych kompetencjach architekta, pominięto elementy instalacyjne i budowlano- -materiałowe. Omawiana aktywność energetyczna dotyczy skali budynków, choć uwzględniono także ich bezpośrednie sąsiedztwo, co pozwala odnieść tę pracę także do niewielkich zespołów zabudowy.

  • Rola niskoprzetworzonych produktów (w tym soków) w diecie, a profilaktyka chorób dietozależnych
    • Edyta Malinowska-Pańczyk
    2020

    Prawidłowo zbilansowana dieta, obok aktywności fizycznej, ma zasadnicze znaczenie w zachowaniu dobrego stanu zdrowia, utrzymaniu prawidłowej masy ciała i zmniejszeniu ryzyka wystąpienia szeregu przewlekłych chorób niezakaźnych takich jak otyłość, cukrzyca i osteoporoza, choroby układu krążenia oraz niektórych rodzajów nowotworów. Obecnie powszechnie uznaje się, że panująca pandemia otyłości i związane z nią choroby są spowodowane zwiększonym spożyciem żywności wysoko przetworzonej, w tym tzw. żywności wygodnej. Uważa się, że podstawą dobrze zbilansowanej diety powinna być tzw. żywność minimalnie przetworzona. Do tej grupy należą produkty żywnościowe, otrzymane z surowców, które zostały poddane procesom niezmieniającym znacząco ich właściwości odżywczych i sensorycznych (np. czyszczenie, usuwanie części niejadalnych, porcjowanie, chłodzenie, itp.). Organizacje zajmujące się zdrowiem publicznym (WHO/FAO) zalecają, aby w codziennej diecie każdej osoby znajdowało się co najmniej 5 porcji różnorodnych owoców i warzyw (około 400 g). Jedna porcja świeżych owoców i warzyw może zostać zastąpiona porcją (200 mL) soku. Korzyści zdrowotne dostarczane przez owoce i warzywa wynikają w dużej mierze z małej gęstości energetycznej tych produktów oraz dużej zawartości w nich mikroelementów, a także związków bioaktywnych o prozdrowotnym działaniu, takich jak witamina C, karotenoidy, flawonoidy i związki fenolowe. Według Zheng i in. (2020) diety bogate w spożycie owoców i warzyw mogą pomóc w zapobieganiu rozwojowi cukrzycy typu 2. Z kolei z metaanaliz badań prospektywnych przeprowadzonych przez Aune w 2019 r. wynika, że istnieje odwrotna zależność między spożyciem owoców i warzyw a ryzykiem choroby wieńcowej, udaru mózgu i chorób układu krążenia ogółem. Najsilniejsze zmniejszenie ryzyka obserwowano u osób spożywających te produkty w ilości 800 g na dzień. Wyniki te zdecydowanie potwierdzają słuszność zaleceń dietetycznych dotyczących spożycia pokarmów roślinnych i sugerują, że optymalne spożycie warzyw i owoców, pozwalające na zapobieganie chorobom przewlekłym może wynosić więcej niż 400 g na dzień (Aune, 2019).

  • Rola wody solwatacyjnej w kształtowaniu aktywności białek z grupy krioprotektantów
    • Joanna Grabowska
    2020 Pełny tekst

    Białka przeciwdziałające zamarzaniu (AFP) posiadają zdolność do hamowania wzrostu kryształów lodu powstających w płynach ustrojowych organizmów żywych narażonych na działanie temperatur niższych od 0°C, poprzez wiązanie się z powierzchnią tych kryształów. W ramach mojej pracy, stosując metody dynamiki molekularnej, starałam się poznać szczegóły mechanizmu zachodzenia tego procesu. Aby to osiągnąć, przeprowadziłam szereg symulacji komputerowych układów o różnej budowie. W pierwszym etapie badań skupiłam się na mechanizmie procesu krzepnięcia wody na powierzchni kryształu lodu i pokazałam, że stopień wewnętrznego uporządkowania kryształu może mieć znaczący wpływ na ten proces. Następnie, przeprowadziłam analizę zmian strukturalnych zachodzących w wodzie wypełniającej obszar między powierzchnią aktywną cząsteczki białka CfAFP i lodem. Na tej podstawie stwierdziłam, że cząsteczka białka jest w stanie zdalnie oddziaływać z powierzchnią lodu, już gdy odległość między tą cząsteczką i lodem przekracza 1 nm. Jak pokazałam, efekt ten związany jest z nakładaniem się warstw solwatacyjnych cząsteczki białka i lodu, i jest przyczyną występowania preferencji względem pewnych wzajemnych odległości i orientacji cząsteczki białka i lodu. Kiedy ułożenie cząsteczki białka względem lodu nie jest optymalne, w układzie pojawia się siła – odpychająca lub przyciągająca – która koryguje jej położenie. Dzięki temu cząsteczka białka może przyjąć taką orientację, która umożliwi jej późniejsze związanie się z lodem.

  • Role of methylation in electron scattering on X(CH3)4 (X = C, Si, Ge) molecules
    • Sylwia Stefanowska-Tur
    • Czesław Szmytkowski
    • Elżbieta Ptasińska-Denga
    • Paweł Możejko
    2020 Pełny tekst Journal of Physics : Conference Series

    Total cross sections (TCS) for low-energy electron scattering from X(CH3)4 (where X = C, Si, Ge) molecules have been measured using linear transmission method. Present results and those obtained previously for XH4 molecules were used to determine how methylation of the target is reflected in TCS energy dependence.

  • Role of methylation in electron scattering on X(CH3)4 (X= C, Si, Ge) molecules (2)
    • Sylwia Stefanowska-Tur
    • Czesław Szmytkowski
    • Elżbieta Ptasińska-Denga
    • Paweł Możejko
    2020 Pełny tekst Journal of Physics : Conference Series

    To investigate how replacement of H atom with methyl group (CH3) – in tetrahedral compounds of carbon, silicon and germanium – affects electron scattering process, total cross sections (TCS) for electron scattering from C(CH3)4, Si(CH3)4 and Ge(CH3)4 molecules have been compared with data for CH4, SiH4 and GeH4 molecules. All examined data have been obtained with the same experimental setup. The shape of all discussed TCS energy dependences is very similar and is characterized by a dominant maximum peaked below 10 eV. For methylated compounds a gentle structure is also visible on high energy slope of main enhancement, between 10 – 20 eV. A simple formula for TCS evaluation for partially methylated carbon, silicon and germanium compounds is also proposed.

  • Role of public space in designing complex urban structures
    • Magdalena Rembeza
    2020 Pełny tekst World Transactions on Engineering and Technology Education

    The aim of this article is to present the main assumptions about design studios as held in the Faculty of Architecture at Gdańsk University of Technology (FA-GUT), Gdańsk, Poland, adapted to the development of key competencies in the urban planning of complex urban structures. One of these competencies is the design of public spaces. The main goal of the studios was to deliver knowledge of the role of public spaces in the design of complex urban structures. During the studios, students learned the need for a systematic approach with various specialists in improving the quality of urban structures. An overview is given of the findings from the urban design studios held, as well as the competencies gained by students. The major conclusion is that teaching the ability to design public spaces connecting urban structures gives students opportunities to better understand complex urban circumstances, as well as offering new challenges in urban planning

  • Role of surface recombination in perovskite solar cells at the interface of HTL/CH3NH3PbI3
    • Damian Głowienka
    • Dong Zhang
    • Francesco Di Giacomo
    • Najafi Mehrdad
    • Sjoerd Veenstra
    • Jędrzej Szmytkowski
    • Galagan Yulia
    2020 Pełny tekst Nano Energy

    In order to achieve the highest performance of organometal trihalide perovskite solar cells, it is required to recognize the dominant mechanisms which play a key role in a perovskite material. In the following studies, we have focused on the interfacial recombination between the hole transporting layer (HTL) and the perovskite CH3NH3PbI3 in solar cell devices with p–i–n architecture. It has been shown that Cu:NiOx : used as HTL drastically decreases a short–circuit photocurrent (Jsc) and an open–circuit voltage (Voc). However, we have found that an addition of PTAA thin layer improves cells quality and, as a consequence, the efficiency of such solar cells increases by 2%. Here, we explain both Jsc and Voc losses with a theory of the “dead layer” of perovskite material where a very high surface recombination occurs. We demonstrate the numerical and experimental studies by the means of series detailed analyses to get in–depth understanding of the physical processes behind it. Using a drift–diffusion model, it is shown that the presence of a parasitic recombination layer influences mostly the current distribution in the simulated samples explaining Jsc and Voc losses. The following results could be useful for improving the quality of perovskite solar cells.

  • Ropa i gaz w gospodarce Azerbejdżanu
    • Krystyna Gomółka
    2020 Pełny tekst Studia Wschodnioeuropejskie

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  • Rotational Molding of Linear Low-Density Polyethylene Composites Filled with Wheat Bran
    • Aleksander Hejna
    • Mateusz Barczewski
    • Jacek Andrzejewski
    • Paulina Kosmela
    • Adam Piasecki
    • Marek Szostak
    • Tairong Kuang
    2020 Pełny tekst Polymers

    Application of lignocellulosic fillers in the manufacturing of wood polymer composites (WPCs) is a very popular trend of research, however it is still rarely observed in the case of rotational molding. The present study aimed to analyze the impact of wheat bran content (from 2.5 wt.% to 20 wt.%) on the performance of rotationally-molded composites based on a linear low-density polyethylene (LLDPE) matrix. Microscopic structure (scanning electron microscopy), as well as physico-mechanical (density, porosity, tensile performance, hardness, rebound resilience, dynamic mechanical analysis), rheological (oscillatory rheometry) and thermo-mechanical (Vicat softening temperature) properties of composites were investigated. Incorporation of 2.5 wt.% and 5 wt.% of wheat bran did not cause significant deterioration of the mechanical performance of the material, despite the presence of ‘pin-holes’ at the surface. Values of tensile strength and rebound resilience were maintained at a very similar level, while hardness was slightly decreased, which was associated with the porosity of the structure. Higher loadings resulted in the deterioration of mechanical performance, which was also expressed by the noticeable rise of the adhesion factor. For lower loadings of filler did not affect the rheological properties. However, composites with 10wt.% and 20 wt.% also showed behavior suitable for rotational molding. The presented results indicate that the manufacturing of thin-walled products based on wood polymer composites via rotational molding should be considered a very interesting direction of research.

  • Rotational state-changing collisions of C2H− and C2N− anions with He under interstellar and cold ion trap conditions: A computational comparison
    • Jan Franz
    • Barry P. Mant
    • Lola González-Sánchez
    • Roland Wester
    • Franco A. Gianturco
    2020 Pełny tekst JOURNAL OF CHEMICAL PHYSICS

    We present an extensive range of quantum calculations for the state-changing rotational dynamics involving two simple molecular anions that are expected to play some role in the evolutionary analysis of chemical networks in the interstellar environments, C2H− (X1Σ+) and C2N− (X3Σ−), but for which inelastic rates are only known for C2H−. The same systems are also of direct interest in modeling selective photo-detachment experiments in cold ion traps where the He atoms function as the chief buffer gas at the low trap temperatures. This study employs accurate, ab initio calculations of the interaction potential energy surfaces for these anions, treated as rigid rotors, and the He atom to obtain a wide range of state-changing quantum cross sections and rates at temperatures up to about 100 K. The results are analyzed and compared for the two systems to show differences and similarities between their rates of state-changing dynamics.

  • Rozpoznawanie urządzeń i wykrywanie nieautoryzowanego poboru energii elektrycznej na podstawie pomiaru napięcia
    • Zdzisław Kowalczuk
    • Marek Grzegorek
    2020 Pełny tekst Pomiary Automatyka Robotyka

    W pracy rozpatrywany jest problem wykrywania nieautoryzowanego poboru energii z sieci elektrycznej przez identyfikację podłączonych urządzeń. Estymacja stanu sieci, rozumianej jako zbiór podpiętych układów, wraz z ustaloną listą urządzeń dopuszczonych, pozwala określić, czy w danej chwili ma miejsce pobór nieautoryzowany. W celu wykrywania urządzeń, proponuje się wykorzystać prostą metodę opartą na analizie wysokoczęstotliwościowego szumu elektromagnetycznego (EMI) indukowanego w sygnale napięcia zasilającego. Rozwiązanie to pozwala na centralny pomiar, w jednym miejscu – bez konieczności instalacji czujników w licznych punktach potencjalnego poboru prądu. Bazując na danych pomiarowych sygnału EMI, zrealizowano symulator syntezujący dane przypominające rzeczywiste spektrogramy. Dzięki zastosowaniu symulatora możliwe jest uzyskanie informacji o stanie sieci w różnych konfiguracjach w celu przeprowadzenia procedury projektowania detektora z użyciem uczenia pod nadzorem, co również jest prezentowane w pracy.

  • Rozwiązania cyfrowe służące eliminacji nieprawidłowości w przedsiębiorstwie świadczącym usługi komunalne - ocena przypadku
    • Marek Wirkus
    • Waldemar Kosiedowski
    2020

    W rozdziale niniejszym poruszono zagadnienie występowania nieprawidłowości w funkcjonowaniu przedsiębiorstwa komunalnego i możliwości ich eliminacji poprzez udoskonalenie istniejących w przedsiębiorstwie rozwiązań opartych na wykorzystaniu technologii cyfrowych. Celem badań była analiza nieprawidłowości wykazanych po okresowych audytach i kontrolach w wybranych obszarach krytycznych i określenie możliwości zabezpieczenia interesów przedsiębiorstwa komunalnego przez technologie cyfrowe, a także ocena odporności systemu obiegu informacji i archiwizacji dokumentów na potencjalne błędy lub nadużycia jego użytkowników.

  • Rozwój przestrzenny małych miast województwa pomorskiego w kontekście procesu metropolizacji
    • Hanna Obracht-Prondzyńska
    2020 Pełny tekst

    Globalizacja oraz dynamiczna urbanizacja przyczyniają się do rosnącego znaczenia procesu metropolizacji, który można uznać za jedną z ważniejszych determinant wpływających obecnie na kształtowanie i zmiany zachodzące w strukturach miejskich i regionalnej sieci osadniczej. Z tego względu coraz częściej poszukuje się narzędzi, umożliwiających stały monitoring zmian zachodzących w wyniku metropolizacji oraz sposobów na szybsze i efektywniejsze reagowanie na negatywne skutki tegoż procesu, prowadzące w rezultacie do narastających dysproporcji w sieci osadniczej regionu. Stanowiło to ważną przesłankę dla sfomułowania celu pracy jakim jest ocena wpływu procesu metropolizacji na rozwój funkcjonalno-przestrzenny miast województwa pomorskiego. Do realizacji tegoż celu posłużył wypracowany model analityczny wykorzystujący wielkie zbiory danych oraz zasoby informacji przestrzennych. Składa się on z dwóch komponentów: (1) w skali regionalnej – oceny siły oddziaływania metropolii, uwzględniając powiązania przestrzenne i funkcjonalne ośrodków miejskich z metropolią, (2) w skali lokalnej – oceny rozwoju przestrzennego i funkcjonalnego małych miast, uwzględniając przy tym zestaw wskaźników odnoszących się do czynników takich jak m.in. stopień urbanizacji, stopień atrakcyjności przestrzeni, jakości życia oraz funkcjonalności struktury urbanistycznej analizowanych ośrodków. Uzyskane wyniki posłużyły do wskazania zależności rozwoju mniejszych ośrodków miejskich od postępującego procesu metropolizacji, w rezultacie do określenia typologii małych miast, a tym samym identyfikacji czynników determinujących współczesne procesy rozwojowe.

  • Rozwój technologii cyfrowych w obszarze ZZL a sytuacja pracowników neuroróżnorodnych
    • Michał Tomczak
    2020

    Celem rozdziału jest analiza istniejących obecnie rozwiązań w obszarze technologii cyfrowych odnoszących się do zarządzania zasobami ludzkimi (ZZL) oraz ustalenie, które spośród nich wydają się szczególnie istotne w kontekście potrzeb coraz liczniejszej grupy osób neuroróżnorodnych.

  • Różne oblicza nanostruktur tlenku tytanu(IV)
    • Marta Kowalkińska
    • Anna Zielińska-Jurek
    2020 Laboratorium

    W niniejszej pracy omówiono różnorodność nanostruktur tlenku tytanu(IV) w odniesieniu do ich zastosowania w fotokatalitycznej degradacji zanieczyszczeń organicznych, szczególnie niepodatnych na rozkład biologiczny.

  • RSS-Based DoA Estimation in 802.11p Frequency Band Using ESPAR Antenna and PPCC-MCP Method
    • Damian Duraj
    • Michał Tarkowski
    • Mateusz Rzymowski
    • Łukasz Kulas
    • Krzysztof Nyka
    2020 Pełny tekst

    In this paper, the concept of direction of arrival (DoA) estimation using electronically steerable parasitic array radiator (ESPAR) antenna designed to operate in IEEE 802.11p vehicular communication standard has been investigated with respect to different possible elevation angles of a radio frequency (RF) signal impinging the antenna. To this end, two different possible sets of the 3D antenna radiation patterns have been used together with power-pattern cross-correlation (PPCC) algorithm and its extension that covers multiple calibration planes (PPCCMCP). Numerical simulations of the PPCC and PPCC-MCP angle estimation procedures at 5.89 GHz have been performed to verify the overall DoA estimation accuracies in the horizontal plane for different, and unknown at the moment of estimation, elevation angles.

  • RSS-Based DoA Estimation Using ESPAR Antenna for V2X Applications in 802.11p Frequency Band
    • Damian Duraj
    • Mateusz Rzymowski
    • Krzysztof Nyka
    • Łukasz Kulas
    2020 Pełny tekst

    In this paper, we have proposed direction-of arrival (DoA) estimation of incoming signals for V2X applications in 802. 11p frequency band, based on recording of received signal strength (RSS) at electronically steerable parasitic array radiator (ESPAR) antenna's output port. The motivation of the work was to prove that ESPAR antenna used to increase connectivity and security in V2X communication can be also used for DoA estimation. The numerical simulation results show that for every proposed radiation pattern we can obtain acceptable DoA estimation results, even with radiation pattern without strong maximum and deep minimum.

  • Rtęć w organizmach żywych – źródła i formy występowania, bioakumulacja, metody oznaczania
    • Piotr Konieczka
    • Małgorzata Rutkowska
    • Małgorzata Misztal-Szkudlińska
    • Piotr Szefer
    2020

    Rtęć (Hg) jest metalem ciężkim o znanej i szeroko badanej toksyczności. Toksyczność rtęci zależy od formy chemicznej tego pierwiastka. Metylortęć (MeHg) jest uważana za najbardziej toksyczną formę rtęci, która po spożyciu jest bioakumulowana i biomagnifikowana w organizmach znajdujących się na kolejnych, następujących po sobie, ogniwach łańcucha pokarmowego. W ekosystemach wodnych, mikroorganizmy przekształcają nieorganiczne formy rtęci w metylortęć. Ta organometaliczna forma może łatwo przenikać przez błony komórkowe i odkładać się w tkankach, wpływa na ośrodkowy układ nerwowy, blokuje również miejsca wiązania enzymów oraz utrudnia syntezę białek. W związku z tym, że rtęć stanowi poważne zagrożenie dla życia i zdrowia ludzkiego, konieczne stało się opracowanie metodyk analitycznych, które będą stanowiły narzędzia do uzyskiwania wiarygodnych informacji analitycznych. W niniejszym rozdziale zestawiono najważniejsze informacje na temat rtęci i jej chemicznych form, źródeł emisji tego pierwiastka do środowiska oraz globalnego cyklu rtęci. Dodatkowo, na podstawie wyników oznaczeń całkowitej zawartości rtęci i jej związków, scharakteryzowano pojęcia bioakumulacji i biomagnifikacji rtęci wzdłuż łańcucha pokarmowego. W rozdziale opisano również metody analityczne wykorzystywane w oznaczaniu rtęci i jej związków.

  • RuAl6—An Endohedral Aluminide Superconductor
    • Zuzanna Ryżyńska
    • Juan Chamorro
    • Tyrel McQueen
    • Piotr Wiśniewski
    • Dariusz Kaczorowski
    • Weiwei Xie
    • Robert J. Cava
    • Tomasz Klimczuk
    • Michał Winiarski
    2020 Pełny tekst CHEMISTRY OF MATERIALS

    Superconductivity is reported in an endohedral aluminide compound, RuAl6, with Tc = 1.21 K. The normalized heat capacity jump at Tc, ΔC/γTc = 1.58, confirms bulk superconductivity. The Ginzburg–Landau parameter of κ = 9.5 shows that RuAl6 is a type-II superconductor. Electronic structure calculations for RuAl6 are explored in comparison to its structural analogue ReAl6 (Tc = 0.74 K). The stability of the phases is discussed in terms of the crystal orbital Hamilton population (−COHP) analysis. The difference in Tc in the two materials is caused by the significantly stronger electron–phonon coupling found in RuAl6, which is a result of significantly stronger antibonding interactions. The presence of superconductivity in yet another compound made of aluminum clusters possibly expands the correlation of critical temperature and the structure shown for Ga-built clusters.

  • Ruch Społeczeństwa Alternatywnego w Gdańsku (1980) 1983-2005…
    • Janusz Waluszko
    2020

    Tekst jest wspomnieniem z działalności w Ruchu Społeczeństwa Alternatywnego i próbą naukowego ujęcia tego w duchu obserwacji uczestniczącej

  • RUSSIANS ON THE POLISH LABOUR MARKET
    • Krystyna Gomółka
    2020 Pełny tekst Review of European and Comparative Law

    The article looks into the employment of Russian citizens in Poland in 2004– 2018. It presents the legal basis for Russians’ entering Poland and taking up work without having to seek a work permit, and specifies who must apply for such a permit. Russian citizens can obtain refugee status under the Geneva Convention, which grants them the right to move freely, choose their place of residence and undertake paid employment, while guaranteeing social security. On the basis of the Act on granting protection to aliens, citizens of the Russian Federation may obtain subsidiary protection if their return to their country of origin may expose them to a real risk of serious harm. A tolerated stay is granted to aliens where an alien might be expelled to a country in which their life, freedom and personal security would be jeopardised, where they could be subjected to torture, degrading treatment, humiliation, forced to work or deprived of the right to a fair trial. Training and employment can be undertaken in Poland under the bilateral agreements between Poland and Russia: the Treaty on friendly and good-neighbourly cooperation and the Cooperation Agreement in the fields of science, culture and education. In Poland, the entry and stay of foreign nationals is governed by the Act on aliens, their education by the Higher Education Act, whereas the employment of foreigners is regulated by the Act on employment promotion and labour market institutions.

  • Ruthenium(II) and Iridium(III) Complexes as Tested Materials for New Anticancer Agents
    • Joanna Masternak
    • Agnieszka Gilewska
    • Barbara Barszcz
    • Iwona Łakomska
    • Katarzyna Kazimierczuk
    • Jerzy Sitkowski
    • Joanna Wietrzyk
    • Anna Kamecka
    • Magdalena Milczarek
    2020 Pełny tekst Materials

    The oncological use of cisplatin is hindered by its severe side eects and a very important resistance problem. To overcome these problems, scientists have attempted to design new generation transition-metal anticancer complexes. In this study, we present new complexes, ruthenium(II) [(6-p-cymene)RuCl(py2CO)]PF6 (1), iridium(III) [(5-Cp)IrCl(py2CO)]PF6 (2), and NH4[IrCl4(py2CO)]H2O (3), based on di-2-pyridylketone (py2CO). The prepared complexes were characterized by FTIR, 1H, 13C, 15N NMR, UV-Vis, PL and elemental analysis techniques. The single-crystal X-ray structure analysis and comparative data revealed pseudo-octahedral half-sandwich 1 and 2 complexes and octahedral tetrachloroiridate(III) 3 with a rare chelating 2N,O coordination mode of py2CO. The compounds were tested in vitro against three cancer cell lines—colorectal adenoma (LoVo), myelomonocytic leukaemia (MV-4-11), breast adenocarcinoma (MCF-7), and normal fibroblasts (BALB/3T3). The most promising results were obtained for iridium(III) complex 3 against MV-4-11 (IC50 = 35.8 13.9 g/mL) without a toxic eect against normal BALB/3T3, which pointed towards its selectivity as a potential anticancer agent. Extensive research into their mode of binding with DNA confirmed for 1 and 2 complexes non-classical binding modes, while the 3D circular dichroism (CD) experiment (DTm) suggested that 3 induced the probable formation of covalent bonds with DNA. In addition, the obtained iridium complexes induce ROS, which, in synergy with hydrolysis promoting DNA bonding, may lead to cancer cell death.

  • Rzeczywiste charakterystyki czasowo-prądowe wyłączników różnicowoprądowych 30 mA przy prądzie sinusoidalnym
    • Stanisław Czapp
    2020 elektro.info

    Przedstawiono wymagania norm odnoszące się do charakterystyki czasowo-prądowej wyłączników różnicowoprądowych o znamionowym prądzie różnicowym zadziałania równym 30 mA. Zaprezentowano wyniki badań laboratoryjnych czasu wyłączania takich wyłączników przy sinusoidalnym prądzie różnicowym i oceniono je z punktu widzenia tych wymagań. Badania wykazały, że czasy wyłączania dwóch lub większej liczby porównywanych wyłączników różnicowoprądowych mogą się znacznie różnić. W przypadku niektórych wyłączników duże różnice w tych czasach wystąpiły dla danego wyłącznika w kolejnych próbach prądem o takich samych parametrach. Jednak jest to zjawisko normalne i nie powinno być podstawą do negatywnej oceny stanu wyłącznika różnicowoprądowego, o ile nie są przekroczone dopuszczalne czasy określone w normie.

  • Safety issues referred to induced sheath voltages in high-voltage power cables – case study
    • Stanisław Czapp
    • Krzysztof Dobrzyński
    2020 Pełny tekst Applied Sciences-Basel

    Load currents and short-circuit currents in high-voltage power cable lines are sources of the induced voltages in the power cables’ concentric metallic sheaths. When power cables operate with single-point bonding, which is the simplest bonding arrangement, these induced voltages may introduce an electric shock hazard or may lead to damage of the cables’ outer non-metallic sheaths at the unearthed end of the power cable line. To avoid these aforementioned hazards, both-ends bonding of metallic sheaths is implemented but, unfortunately, it leads to increased power losses in the power cable line, due to the currents circulating through the sheaths. A remedy for the circulating currents is cross bonding – the most advanced bonding solution. Each solution has advantages and disadvantages. In practice, the decision referred to its selection should be preceded by a wide analysis. This paper presents a case study of the induced sheath voltages in a specific 110 kV power cable line. This power cable line is a specific one, due to the relatively low level of transferred power, much lower than the one resulting from the current-carrying capacity of the cables. In such a line, the induced voltages in normal operating conditions are on a very low level. Thus, no electric shock hazard exists and for this reason, the simplest arrangement – single-point bonding – was initially recommended at the project stage. However, a more advanced computer-based investigation has shown that in the case of the short-circuit conditions, induced voltages for this arrangement are at an unacceptably high level and risk of the outer non-metallic sheaths damage occurs. Moreover, the induced voltages during short circuits are unacceptable in some sections of the cable line even for both-ends bonding and cross bonding. The computer simulations enable to propose a simple practical solution for limiting these voltages. Recommended configurations of this power cable line – from the point of view of the induced sheath voltages and power losses – are indicated.

  • SAILING ROUTE PLANNING METHOD CONSIDERING VARIOUS USER CATEGORIES
    • Marcin Życzkowski
    2020 Pełny tekst Polish Maritime Research

    The article describes the methodology related to determining the multi-criteria routes for sailing ships. Details of sea area discretisation and discretisation of the description of the sailing vessel properties and manoeuvring principles are shown. User requirements were specified (for five different categories of users) and on this basis the criteria for selecting the most suitable shipping route were formulated. The presented algorithm recommends a route for a given user category by means of defined restrictions and configuration parameters. The applied multi-criteria approach proves the universality and usability of the sailing ship route planning method.

  • Salinity enhances high optically active L-lactate production from co-fermentation of food waste and waste activated sludge: Unveiling the response of microbial community shift and functional profiling
    • Xiang Li
    • Safeena Sadiq
    • Wenjuan Zhang
    • Yiren Chen
    • Xianbao Xu
    • Anees Abbas
    • Shanping Chen
    • Ruina Zhang
    • Gang Xue
    • Dominika Sobotka
    • Jacek Mąkinia
    2020 Pełny tekst BIORESOURCE TECHNOLOGY

    Lactic acid (LA), a versatile platform molecule, can be fermented from organic wastes, such as food waste and waste activated sludge. In this study, an efficient approach using salt, a component of food waste as an additive, was proposed to increase LA production. The LA productivity was increased at 10 g NaCl/L and optical pure L-lactate was obtained at 30 g NaCl/L. The enhancement of LA was in accordance with the increased solubilization and the critical hydrolase activities under saline conditions. Moreover, high salinity (30-50 g NaCl/L) changed the common conversion of LA to volatile fatty acids. In addition, the key LA bacteria genera (Bacillus, Enterococcus, Lactobacillus) were selectively enriched under saline conditions. Strong correlations between salinity and functional genes for L-LA production were also observed. This study provides a practical way for the enrichment of L-LA with high optical activity from organic wastes.

  • Scalable Route toward Superior Photoresponse of UV-Laser-Treated TiO2 Nanotubes
    • Łukasz Haryński
    • Katarzyna Grochowska
    • Jakub Karczewski
    • Jacek Ryl
    • Katarzyna Siuzdak
    2020 ACS Applied Materials & Interfaces

    Titanium dioxide nanotubes gain considerable attention as a photoactive material due to chemical stability, photocorrosion resistance, or lowcost manufacturing method. This work presents scalable pulsed laser modification of TiO2 nanotubes resulting in enhanced photoactivity in a system equipped with a motorized table, which allows for modifications of both precisely selected and any-large sample area. Images obtained from scanning electron microscopy along with Raman and UV−vis spectra of laser-treated samples in a good agreement indicate the presence of additional laser-induced shallow states within band gap via degradation of crystalline structure. However, X-ray photoelectron spectroscopy spectra revealed no change of chemical nature of the modified sample surface. Photoelectrochemical measurements demonstrate superior photoresponse of laser-treated samples up to 1.45-fold for an energy beam fluence of 40 mJ/cm2 compared to that of calcined one. According to the obtained results, optimal processing parameters were captured. Mott−Schottky analysis obtained from impedance measurements indicates an enormous (over an order of magnitude) increase of donor density along with a +0.74 V positive shift of flat band potential. Such changes in electronic structure are most likely responsible for enhanced photoactivity. Thus, the elaborated method of laser nanostructuring can be successfully employed to the large-scale modification of titania nanotubes resulting in their superior photoactivity. According to that, the results of our work provide a contribution to wider applications of materials based on titania nanotubes.

  • Scenario-planning solutions for waterfront flood-prone areas
    • Lucyna Nyka
    • Izabela Burda
    2020 Pełny tekst Global Journal of Engineering Education

    The aim of this article is to discuss the potential of applying scenario planning to achieve resilient and future-oriented solutions for flood-prone areas. The authors have proposed additions to scenario-planning processes based on the introduction of research-by-design architectural inquiries. Examined in this article is the insight into the testing of such a modified scenario-planning methodology during two courses that accompanied researcher stakeholder workshops organised within the H2020 project SOS Climate Waterfront in the Faculty of Architecture at Gdańsk University of Technology (FA-GUT), Gdańsk, Poland. The task for the students was to propose plausible future scenarios for the flood-prone area of the Polish Hook peninsula in Gdańsk. Based on this experiment, the authors have proposed using research-by-design tools in scenario-planning practices, and they discuss the benefits of research-based learning.

  • Scenariusze w kształtowaniu inteligencji strategicznej województw
    • Jacek Sołtys
    2020

    ..

  • Scientific Collaboration, Citation and Topic Analysis of International Conference on Agile Software Development Papers
    • Muhammad Ahmad
    • Päivi Raulamo-jurvanen
    2020

    The International Conference on Agile Software Development (XP) was established almost sixteen years ago. Based on data from Scopus database, a total of 789 papers have been published in between years of 2002 and 2018. We employed bibliometrics analysis and topic modeling with R/RStudio to analyze these published papers from various dimensions, including the most active authors, collaboration of authorship, most cited papers, used keywords and trends of probable topics from the titles and abstracts of those papers. The results show that the first five years of XP conference cover nearly 40% of the papers published until now and almost 62% of the XP papers have been cited at least once. Mining of XP conference paper titles and abstracts result in these hot research topics: “Coordination”, “Technical Debt”, “Teamwork”, “Startups” and “Agile Practices”, thus strongly focusing on practical issues and problems faced by the practitioners in the industry. The results highlight the most influential researchers and institutions, and the collaboration between the authors in the conference papers. The approach applied in this study can be extended to other software engineering venues and can be applied to large-scale studies.

  • Seabed Topography Changes in the Sopot Pier Zone in 2010–2018 Influenced by Tombolo Phenomenon
    • Artur Makar
    • Cezary Specht
    • Mariusz Specht
    • Paweł Dąbrowski
    • Paweł Burdziakowski
    • Oktawia Lewicka
    2020 Pełny tekst SENSORS

    Bathymetric surveys of the same body of water, performed at regular intervals, apart from updating the geospatial information used to create paper and electronic maps, allow for several additional analyses, including an evaluation of geomorphological changes occurring in the coastal zone. This research is particularly important in places where the shape of the coastal zone has been violently disturbed, including by human activity. Tombolo is such a phenomenon and it dynamically shapes the new hydrological conditions of the coastal zone. Apart from natural factors, it may be caused by the construction of hydrotechnical facilities in the littoral zone. It causes a significant disturbance in the balance of the marine environment, resulting in the bottom accretion and dynamic changes in the coastline. This has been the case since 2010 in Sopot, where the rapidly advancing tombolo is not only changing environmental relations but also threatening the health-spa character of the town by stopping the transport of sand along the coast. This paper analyses changes in seabed shape in the pier area in Sopot between 2010 and 2018. In the analysis, both archival maps and bathymetric surveys over a period of 8 years were used; based on these, numerical bottom models were developed and their geospatial changes were analyzed. The results showed that changes in the seabed in this area are progressing very quickly, despite periodic dredging actions organized by administrative bodies.

  • Searching for Solvents with an Increased Carbon Dioxide Solubility Using Multivariate Statistics
    • Marta Bystrzanowska
    • Marek Tobiszewski
    • Francisco Pena-Pereira
    • Vasil Simeonov
    2020 Pełny tekst MOLECULES

    Ionic liquids (ILs) are used in various fields of chemistry. One of them is CO2 capture, a process that is quite well described. The solubility of CO2 in ILs can be used as a model to investigate gas absorption processes. The aim is to find the relationships between the solubility of CO2 and other variables—physicochemical properties and parameters related to greenness. In this study, 12 variables are used to describe a dataset consisting of 26 ILs and 16 molecular solvents. We used a cluster analysis, a principal component analysis, and a K-means hierarchical clustering to find the patterns in the dataset and the discriminators between the clusters of compounds. The results showed that ILs and molecular solvents form two well-separated groups, and the variables were well separated into greenness-related and physicochemical properties. Such patterns suggest that the modeling of greenness properties and of the solubility of CO2 on physicochemical properties can be difficult.

  • Seashore sediment and water chemistry at the Admiralty Bay (King George Island, Maritime Antarctica) – geochemical analysis and correlations between the concentrations of chemical species
    • Joanna Potapowicz
    • Danuta Szumińska
    • Małgorzata Szopińska
    • Robert Józef Bialik
    • Katarzyna Machowiak
    • Stanisław Chmiel
    • Żaneta Polkowska
    2020 MARINE POLLUTION BULLETIN

    This study covers water and sediment chemical characteristics by the western shore of Admiralty Bay (King George Island, Antarctica) in 2016. Chemical processes between sediment and water have been described based on the determination of ions, metals, non-metals, and TOC concentrations. Rock weathering is an important source of Fe, Ni, Co, Al in the seashore area. The PCA shows the impact of acidification in the release metals from sediment. Our results indicate that riverine mineral fluxes need to be accounted for as the volume of melt increases in response to climate change. Based on geoaccumulation indexes (anthropogenic fingerprint), we observed an increased concentration of Pb (Igeo=1.643), in the lake near station facilities and Cd in the area of Ecology Glacier (Igeo>1.389). Taking into account climate change and the intensification of anthropopressure, our study indicates that Antarctica requires a special focus on the seasonal dynamics of mineral content and pollution assessment.

  • Seasonal contributions of nutrients from small urban and agricultural watersheds in northern Poland
    • Karolina Matej-Łukowicz
    • Ewa Wojciechowska
    • Nicole Nawrot
    • Lidia Dzierzbicka-Głowacka
    2020 Pełny tekst PeerJ

    Diffuse sources of pollution like agricultural or urban runoff are important factors in determining the quality of surface waters, although they are more difficult to monitor thanpointsources.Theobjectiveofourstudywastoverifyassumptionsthattheinflow from agricultural nutrient sources is higher than from urbanized ones. It has been done by comparing the nutrients and organic matter concentrations and loads for three small streams in northern Poland (Pomerania Region). Two streams flowing through agricultural catchments and an urban stream flowing through the city of Gdansk were analysed. Concentrations of nutrients: N-NO− 3 N-NH+ 4 , P-PO3− 4 , total phosphorus, total nitrogen and COD were measured 1–3 times per month in the periodfromJuly2017toDecember2018inagriculturalwatershedsandfromOctober 2016 to March 2018 for an urban stream. Seasonal changes in concentrations were analysed with descriptive statistics tools. Principal Component Analysis (PCA) was used to point out the most significant factors determining variations in nutrients and organic matter concentrations with respect to different seasons. The factors included a number of characteristics regarding the catchment and streams: total catchment area, stream length, watershed form ratio, stream slope, flow rate and land use with respecttopavedareas,agriculturalareasandgreenareas(parks,forests,meadowsand pastures). Although concentrations of nitrogen compounds were higher in streams flowing through agricultural areas, our study showed that total concentrations of phosphoruswerehigherintheurbanstream,especiallyinsummer.Inagriculturalareas thesummerconcentrationsofnutrientswerenothigh,whichwasprobablyduetodense vegetation.ThecorrelationbetweenP-PO3− 4 concentrationandsizeofagriculturalarea in the catchment was observed in winter when no vegetation field cover exists. Our study shows an urgent need to monitor the nutrient loads carried with urban streams especially if discharged into receivers prone to eutrophication.

  • Secured wired BPL voice transmission system
    • Grzegorz Debita
    • Przemysław Falkowski-Gilski
    • Marcin Habrych
    • Bogdan Miedziński
    • Jan Wandzio
    • Przemysław Jedlikowski
    2020 Pełny tekst Scientific Journal of the Military University of Land Forces

    Designing a secured voice transmission system is not a trivial task. Wired media, thanks to their reliability and resistance to mechanical damage, seem an ideal solution. The BPL (Broadband over Power Line) cable is resistant to electricity stoppage and partial damage of phase conductors, ensuring continuity of transmission in case of an emergency. It seems an appropriate tool for delivering critical data, mostly clear and understandable voice messages. This paper describes such a system that was designed and evaluated in real-time operating conditions. It involved a two-way transmission of speech samples in American English and Polish. The efficiency of the designed solution was evaluated in the subjective study on a group of 15 people.

  • Selected adipocytokines in patients with an incidentally discovered pheochromocytoma
    • Mariusz Kaszubowski
    • Ania Babińska
    • P. Kmieć
    • Krzysztof Sworczak
    2020 Minerva Endocrinologica

    BACKGROUND: Adipose tissue secretes many adipokines and cytokines, which may be an additional risk factor of cardiovascular and metabolic diseases in patients with an incidentally discovered pheochromocytoma (PHEO). The aim of the study was to investigate levels of selected adipocytokines in these patients. METHODS: This prospective study included 12 patients with an incidentally discovered PHEO and 18 healthy participants. In all participants plasma/serum concentrations of triglycerides, HDL and LDL cholesterol, insulin, glucose, adipocytokines (adiponectin, leptin, resistin, TNFα, IL6, and MCP1) were determined, hormonal tests were performed in patients. RESULTS: Patients and controls did not differ significantly in terms of age, sex, and body mass index. Among incidentally discovered PHEO patients, adiponectin levels were lower, while TNFα concentrations higher than in controls. Concentrations of adiponectin correlated with 24-hour urinary excretion of normetanephrine in women. Significantly higher TNFα concentrations were found in hypertensive than in normotensive PHEO patients as well as in non-diabetic PHEO patients than controls. Further, resistin concentration was higher in PHEO patients with diabetes than in non-diabetic ones (p<0.001). Incidentally discovered PHEO tumor size correlated with leptin and IL6 levels. Adiponectin levels were higher, while TNFα and resistin lower among five patients re-examined after tumor resection. CONCLUSIONS: Among patients with an incidentally discovered pheochromocytoma, lower adiponectin, and higher resistin and TNFα levels may constitute additional factors for HT and DM. In our study, for the first time, correlations between incidentally discovered PHEO tumor size and concentrations of leptin as well as IL6 were found.

  • Selected issues of women's participation in labour market and on boards of family entreprises
    • Anita Richert-Kaźmierska
    2020

    The chapter presents cultural determinants of roles attributed to women, as well as their situation in the labour market and in family businesses. The main aim of the study is to trace the changes in the social image of women’s roles in the labour market. The observations made are based on the changes in the value of the economic activity rate among women in the Baltic Sea Region (BSR) countries, as well as on the feminisation rate among managers, employees and successors of family businesses.

  • Selected local stability problems of channel section flanges made of aluminium alloys
    • Marcin Kujawa
    2020 Pełny tekst CONTINUUM MECHANICS AND THERMODYNAMICS

    The paper addresses the issue of local buckling of compressed flanges of cold-formed thin-walled channel columns and beams with nonstandard flanges composed of aluminium alloys. The material behaviour follows the Ramberg–Osgood law. It should be noted that the proposed solution may be also applied for other materials, for example: stainless steel, carbon steel. The paper is motivated by an increasing interest in nonstandard cold-formed section shaping in local buckling analysis problems. Furthermore, attention is paid to the impact of material characteristics on buckling stresses in a nonlinear domain. The objective of the paper is to propose a finite element method (FEM) model and a relevant numerical procedure in ABAQUS, complemented by an analytical one. It should be noted that the proposed FEM energetic technique makes it possible to compute accurately the critical buckling stresses. The suggested numerical method is intended to accurately follow the entire structural equilibrium path under an active load in elastic and inelastic ranges. The paper is also focused on correct modelling of interactions between sheets of cross section of a possible contact during buckling analysis. Furthermore, the FEM results are compared with the analytical solution. Numerical examples confirm the validity of the proposed FEM procedures and the closed-form analytical solutions. Finally, a brief research summary is presented and the results are discussed further on.

  • Selection of C-Type Filters for Reactive Power Compensation and Filtration of Higher Harmonics Injected into the Transmission System by Arc Furnaces
    • Andrzej, Grzegorz Lange
    • Grzegorz Redlarski
    2020 Pełny tekst ENERGIES

    This article presents a method for selecting the elements of a C-type filter working with a conventional LC-type filter for compensating reactive power and filtering out higher harmonics generated by arc furnaces and ladle furnaces. The study was conducted in a steel mill supplied by a 110 kV transmission system, where higher harmonic currents and nonlinear loads were measured. A series of computer simulations were performed under various operating conditions, and an algorithm for selecting the parameters of a third-order C-type filter (for suppressing the second harmonic) and two second-order LC-type filters (for suppressing the third harmonic) was proposed. The filtering system was tested in an arc furnace with the highest rated power, and harmonics in the current spectrum were evaluated. The results of the measurements were used to analyze the effectiveness of the compensation system comprising two passive C-type and LC-type filters at different system configurations. C-type filters significantly influenced current harmonics. The influence of the changes in the number of arc furnace transformers on the true Root Mean Square (RMS) of the currents injected into the 110 kV transmission system and on the voltages of the 110 kV busbars was discussed.

  • Self-standing Nanoarchitectures
    • Siuzdak Katarzyna
    • Łukasz Haryński
    • Jakub Wawrzyniak
    • Piotr Kupracz
    • Katarzyna Grochowska
    2020 Pełny tekst

    Despite there are structures invisible for the human eye, they mastered the world of advanced electronic devices, sensors, novel cosmetics or drugs. When the dimensions of the materials go down to the nanometres scale, their properties change dramatically comparing to the observable objects. Because of their tiny size, they gained the name of nanomaterials but simultaneously their importance has significantly grown up. Nanomaterials exhibit superb features such as a distinctive catalytic activity, hydrophobicity, photoconversion activity and biological affinity. Following that, even a small amount of nanomaterials is sufficient to provide unusual properties to the final products such as coatings, active layers in solar cells, clothes, electrodes and electrolytes used for energy storage devices. Owing to the rapid development in the synthesis methods and characterization techniques, especially those used for morphology inspection, we can investigate them in details on the molecular scale and describe the mechanism that stays behind improved antimicrobiological activity, hydrophobicity, capacitance or catalytic properties. Despite the number of usable elements is limited, the diversity of morphologies, namely rods, particles, tubes, planes and the possibility of heterostructures formation, provides researchers the wide room for maneuverer. Sometimes, only small change in the material geometry, structure or a little amount of introduced dopant atoms is enough to obtain completely new nanomaterial that has not been known so far. Therefore, we should not be surprised how fast surrounding environment is changing and our everyday life is supported by the novelties from the nano world. The aim of this chapter is to present the diversity of nanomaterials taking into account their dimensions, shape and composition. Herein, particles, tubes, wires, pores, walls, exhibiting at least one dimension within the nanoscale will be evoked. Moreover, the nanostructures that morphology reminds well known objects from nature are discussed. The description of some interesting examples is supported by the extraordinary SEM images illustrating the beauty unavailable for naked eye.

  • Self-Supervised Learning to Increase the Performance of Skin Lesion Classification
    • Arkadiusz Kwasigroch
    • Michał Grochowski
    • Agnieszka Mikołajczyk
    2020 Pełny tekst Electronics

    To successfully train a deep neural network, a large amount of human-labeled data is required. Unfortunately, in many areas, collecting and labeling data is a difficult and tedious task. Several ways have been developed to mitigate the problem associated with the shortage of data, the most common of which is transfer learning. However, in many cases, the use of transfer learning as the only remedy is insufficient. In this study, we improve deep neural models training and increase the classification accuracy under a scarcity of data by the use of the self-supervised learning technique. Self-supervised learning allows an unlabeled dataset to be used for pretraining the network, as opposed to transfer learning that requires labeled datasets. The pretrained network can be then fine-tuned using the annotated data. Moreover, we investigated the effect of combining the self-supervised learning approach with transfer learning. It is shown that this strategy outperforms network training from scratch or with transfer learning. The tests were conducted on a very important and sensitive application (skin lesion classification), but the presented approach can be applied to a broader family of applications, especially in the medical domain where the scarcity of data is a real problem.

  • Sensor Position Estimation Method for IoT Using Mobile Reference Node
    • Jacek Stefański
    • Jarosław Sadowski
    2020 Pełny tekst IEEE Access

    The paper proposes an innovative method of locating objects for the Internet of Things (IoT). The proposed method allows the position of a fixed measuring sensor (MS) to be estimated using one mobile base station with a known position moving around the MS. The mathematical analysis of the method, and three algorithms — Newton’s (NA), gradient descent (GD) and genetic (GA) — for solving the system of non-linear positional equations are presented. Next, the analysis of the position dilution of precision (PDoP) parameter for the proposed method, and the Cramér-Rao lower bound (CRLB), limiting the accuracy of the method, are presented. Finally, the results of complex simulation studies on the efficiency of the proposed method for various selected system parameters of the sensor network and convergence of the algorithms used to solve the system of non-linear equations are described.