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Gdańsk University of Technology

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Publications from the year 2021

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  • Shadow Economy in Poland Recent Evidence Based on Survey Data
    • Dagmara Nikulin
    • Ewa Lechman
    2021

    The book provides an estimate of the size of the shadow economy in Poland. Using analogous data, it traces core determinants of the existence of the shadow economy in Poland. It compares results with neighbouring countries, and if possible, the remaining Central-Eastern economies. The book tells why the problem of the unreported economic activity matters; it presents the problem from different angles―economic, social and institutional. Next, it extensively reviews past research on the size and determinants of the shadow economy in Poland. It discusses available resources and empirical results showing the problem from micro-, and macroeconomic perspective. The authors present the methods used and the results of the survey, which are interpreted and discussed Finally it concludes on major drivers of shadow economy in Poland, providing recommendations and future research directions. The book is intended for practitioners and those seeking understanding of undeclared economic activities.

  • Shaft friction from the DMT and direct shear interface tests
    • Kamila Mikina
    • Jakub Konkol
    • Lech Bałachowski
    2021

    The article presents preliminary attempt to create tri-linear transfer curves for describing pile behaviour under axial loading. Transfer curves would use the parameter measured in dilatometer test, particularly a constrained modulus MDMT. The proposed method is based on concrete rough and smooth interface tests performed in a direct shear apparatus. Based on the obtained mobilization curves, relationships were created between the parameters describing the slope of individual transfer curves and the MDMT modulus. The obtained correlations were used to estimate the capacity of the concrete screw pile subjected to the static load test in tension.

  • Shape and force control of cable structures with minimal actuators and actuation
    • Najmadeen Saeed
    • Ahmed Manguri
    • Abubakr Adabar
    2021 International Journal of Space Structures

    Shape adjustment and stress control can be considered as one of the effective parameters in prestressed cable structures since such structures are widely constructed nowadays due to their characteristics. The assembly errors and applied loads hugely affect the cables’ nodal positions and stress due to their delicacy. The former could disturb the shape, which affects the appearance and the function of the structure. In contrast, the latter may increase the stress in some cables above the upper limit or induce slack in some others. Accordingly, a technique has been proposed that combined fmincon optimization that relies on four different algorithms with a controlling approach based on the force method. The presented method aims to minimize the total amount of actuation and miniaturize the number of actuators. The targets of previously confirmed techniques can be obtained with less actuation and fewer actuators by using the current technique. Based on the verified examples, the advantage of the current approach over the quoted methods is up to 55% and 37% in terms of the number of actuators and the total amount of actuation, respectively.

  • Shape Memory Materials from Rubbers
    • Arunima Reghunadhan
    • Paduvilan Jibin
    • Vayyaprontavida Kaliyathan
    • Prajitha Velayudhan
    • Michał Strankowski
    • Sabu Thomas
    2021 Full text Materials

    Smart materials are much discussed in the current research scenario. The shape memory effect is one of the most fascinating occurrences in smart materials, both in terms of the phenomenon and its applications. Many metal alloys and polymers exhibit the shape memory effect (SME). Shape memory properties of elastomers, such as rubbers, polyurethanes, and other elastomers, are discussed in depth in this paper. The theory, factors impacting, and key uses of SME elastomers are all covered in this article. SME has been observed in a variety of elastomers and composites. Shape fixity and recovery rate are normally analysed through thermomechanical cycle studies to understand the effectiveness of SMEs. Polymer properties such as chain length, and the inclusion of fillers, such as clays, nanoparticles, and second phase polymers, will have a direct influence on the shape memory effect. The article discusses these aspects in a simple and concise manner.

  • Shape-Memory Polyurethane Polymers
    • Michał Strankowski
    • Paul Anju
    • Arunima Reghunadhan
    2021 Full text ACS SYMPOSIUM SERIES

    Polyurethanes (PUs) are one of the most widely used polymers in research and industry. They can be synthesized from chemical sources and natural sources. PUs are a very useful class of polymers and exhibit many desirable properties that can be exploited in various applications. PUs are formed by the reaction between polyols and isocyanates. A wide variety of polyols and isocyanates are available for synthesis, and hence we can produce a large number of PUs. PUs show high mechanical strength, chemical resistance, flexibility, and resilience. One of the major advantages of some specially designed PUs is their ability to recover their primary shape, which is known as shape memory. The shape-memory effect (SME) of PUs makes them popular in biomedical, electronic, and thermal applications. The SME can be monitored using different measures such as shape fixity, recovery time, and recovery rate. Various stimuli are applied to shape-memory materials to induce shape memory. PU polymers can be modified with different nanofillers, and these fillers influence the shape-recovery parameters. PU composites are popular because of a good property–price relationship. This chapter discusses the various factors affecting the SME of PU composites and the effect of different types of fillers on the PU matrix.

  • Shaping the City Responding to Climate Change – Concept of Development of the Right Bank of the Vistula River in Toruń, Poland,
    • Sylwia Sitniewska
    • Justyna Borucka
    2021

    The problems of cities of the 21st century are caused by anthropogenic oppression of the environment, through the growth of economic activity and continuous urbanisation, and taking away ecologically important open areas and biologically active areas. Increasingly frequent and sudden rains, strong winds, turbulence and rising world water levels are some of the consequences of climate change that have a direct impact on the functioning of cities. The article presents a study of a land-use plan for the right bank of the Vistula river in Toruń, Poland, in reference to ongoing climate change. The authors focus on the main assumption of this concept, which is to protect the area from increasing river floods expected due to strong climate change impact on Earth’s water cycle and temporary river water rise. The project strategy focussed on reshaping the Vistula river bank, as well as designing a solution that would allow floodwater to enter the area in a controlled manner. The newly designed area presented in the article is an attempt at conscious urban planning as well as planning activities in harmony with nature, and shows how such an approach to city planning can face the problems of climate change and could be a possible solution for future development of the city of Toruń.

  • Shear band evolution phenomena in direct shear test modelled with DEM.
    • Michał Nitka
    • Aleksander Grabowski
    2021 Full text POWDER TECHNOLOGY

    A direct shear test is widely used in the geotechnical engineering field. It is an easy and quick test to measure the shear properties of soil. This test often replaces more expensive and difficult tri-axial shear test. Despite that the direct shear test is known and used for a long time, it is still not well investigated at the grain scale. This paper deals with the micro behaviour of the cohesionless sand inside the direct shear box during a geotechnical test. Numerical calculations were performed with open-source discrete code YADE. The full 3D model was used, in order to eliminate some non-physical phenomena. The numerical stress-strain curve was directly compared with the laboratory results and good agreement was obtained. The focus was on the shape of the localized zone, the properties of this zone and its behaviour. The movement of the individual grains was studied. In our analysis, the stresses were also taken into consideration. The conclusions were validated on tests with different initial void ratio (dense or loose material) and with different vertical pressure.

  • Shear fracture of longitudinally reinforced concrete beams under bending using Digital Image Correlation and FE simulations with concrete micro-structure based on X-ray micro-computed tomography images
    • Łukasz Skarżyński
    • Ireneusz Marzec
    2021 Full text CONSTRUCTION AND BUILDING MATERIALS

    The paper presents experimental and numerical investigations of the shear fracture in rectangular concrete beams longitudinally reinforced with steel or basalt bar under quasi-static three point bending. Shear fracture process zone formation and development on the surface of beams was investigated by Digital Image Correlation (DIC) whereas thorough analyses of 3D material micro-structure, air voids, width and curvature of shear cracking were carried out by X-ray micro-computed tomography (micro-CT). Moreover, the 2D shear fracture patterns in beams were numerically simulated with the finite element method (FEM) using isotropic coupled elasto-plastic-damage constitutive model for concrete enhanced by a characteristic length of micro-structure. Concrete meso-structure was modelled as a random heterogeneous four-phase material composed of aggregate particles, cement matrix, ITZ zones and air voids on the basis of X-ray micro-CT images. Experimental and numerical results revealed a satisfactory agreement regarding to the mechanism of failure, load-bearing capacity as well as cracking pattern.

  • Short-Term Price Reaction to Filing for Bankruptcy and Restructuring Proceedings—The Case of Poland
    • Błażej Prusak
    • Marcin Potrykus
    2021 Full text Risks

    This study aims to check market reaction to filing for bankruptcy and restructuring proceedings and to verify the short-term effect of a price reversal in the Polish market in the years 2004–2019. The research was conducted by dividing the analysed companies according to the procedure (bankruptcy and restructuring) and market (the main market and the NewConnect market). The research methodology used in the study is the event analysis method (AR, CAR, AAR and CAAR rates were used in the research), with a few statistical tests (T-test, Generalized rank Z Test, Gen-eralized rank T-Test, Patell or Standardized Residual Test, Kolari and Pynnönen adjusted Patell or Standardized Residual Test). It was found that share prices in the Polish share market react quickly to public information about filing an application for bankruptcy or restructuring. For all analysed companies, the mean rate of return on the event day was equal to −14%, and on the next day, it was −3%. Regardless of the type of share market and the form of proceedings, the reversal effect was not confirmed in the short term. It was found that cumulative above-average rates of return fall more strongly for companies listed on the less liquid Newconnect market (−23.6%), and when information on the filing for bankruptcy proceedings is provided (−28.5%), as opposed to the main market (−19.1%) and restructuring proceedings (−17%). The cumulative average rate of return for all analysed companies in the research period (−2, +10 days) was equal to −20.6%.

  • Siderofory bakteryjne – rola w patogenezie i potencjał wykorzystania w diagnostyce
    • Beata Krawczyk
    • Aleksandra Rosińska
    2021 Full text

    Do prawidłowego funkcjonowania i wzrostu organizmów żywych zarówno ludzi, jak i bakterii niezbędne jest żelazo. Mikroelement ten występuje na dwóch różnych stopniach utlenienia: jako jon żelazawy (Fe2+) rozpuszczalny w roztworach fizjolo-gicznych oraz jako jon żelazowy (Fe3+), który nie tworzy roztworów wodnych [1]. Dzięki swoim właściwościom oksydo-redukcyjnym, żelazo wpływa na poprawne funkcjonowanie bardzo licznej grupy enzymów, m.in. cytochromów, oksydoreduktaz NADH-CoQ10, oksydoreduktazy bursztynianu-CoQ10. Enzymy te biorą udział w ważnych dla życia procesach metabolicznych, w czasie których produkowane są cząsteczki ATP. Bez udziału żelaza niemożliwe jest oddychanie. Żelazo wchodzi w skład hemoglobiny – białka transportującego tlen z płuc do wszystkich komórek w ludzkim organizmie. Ponadto bierze udział w neurogenezie, różnicowaniu komórek mózgu oraz jest kofaktorem licznych enzymów uczestniczących w syntezie neuro-przekaźników. W sytuacji niedoboru żelaza odpowiedź układu odpornościowego jest bardzo osłabiona [1, 2]. W komórkach bakteryjnych rola tego pierwiastka jest równie istotna i opiera się na zdolności jonów żelaza do utleniania i redukcji. Enzymy redoks znajdują się w cytozolu lub związane są z błoną komórkową, a jednym z ważniejszych jest reduktaza rybo-nukleotydowa – kluczowy enzym w procesie syntezy DNA. Ponadto jon żelazowy często jest końcowym akceptorem elektronów w łańcuchu oddechowym bakterii beztlenowych [3]. Do prawidłowego funkcjonowania i wzrostu komórka bakteryjna wymaga 10-7 M wolnych jonów żelazowych. W organizmie żywiciela bakteria musi zmierzyć się z bardzo ograniczonym dostępem do tego kluczowego pierwiastka. Większość komórko-wego żelaza gospodarza jest związana z jego białkami, a stężenie wolnych jonów żelaza we krwi jest o wiele za niskie do swobodnej dyfuzji. Aby zaspokoić zapotrzebowanie na ten mikroelement, mikroorganizmy produkują siderofory, czyli różnorodne che-micznie cząsteczki chelatujące jony i rozpoczynają konkurencję z gospodarzem o do-stępną pulę żelaza [3].

  • Sieci neuronowe oparte na prawach fizyki
    • Marek Moszyński
    • Bartłomiej Borzyszkowski
    • Karol Damaszke
    • Jakub Romankiewicz
    • Marcin Świniarski
    2021

    Wiele fizycznie nieuzasadnionych sieci neuronowych, mimo zadowalają- cej wydajności, generuje sprzeczności z logiką i prowadzi do rozbieżno- ści wyników z rzeczywistością. Jedną z metod poprawy funkcjonowania typowego modelu typu “black-box” na etapie uczenia, jest rozszerzenie jego funkcji kosztu o zależność bezpośrednio inspirowaną wzorem fizycz- nym. Niniejszy rozdział wyjaśnia koncepcję budowy sieci neuronowych opartych na prawach fizyki, zawiera przegląd zaproponowanych rozwią- zań w tej dziedzinie oraz opisuje możliwości implementacji funkcji strat wykorzystujących wzory fizyczne. Ponadto przedstawione badania poka- zują, że przewidywania algorytmów inspirowanych przez fizykę mogą być nie tylko optymalne, ale również naukowo spójne z równaniami dziedzi- nowymi. Ostatecznie wykorzystanie wiedzy naukowej zawartej w dosto- sowanych funkcjach kosztów pokazuje, że metodyka ta gwarantuje wy- niki spójne z prawami fizyki, a także lepszą generalizację w porównaniu z klasycznymi sieciami neuronowymi.

  • Signal Propagation in Electromagnetic Media Modelled by the Two-Sided Fractional Derivative
    • Jacek Gulgowski
    • Dariusz Kwiatkowski
    • Tomasz Stefański
    2021 Full text Fractal and Fractional

    In this paper, wave propagation is considered in a medium described by a fractional-order model, which is formulated with the use of the two-sided fractional derivative of Ortigueira and Machado. Although the relation of the derivative to causality is clearly specified in its definition, there is no obvious relation between causality of the derivative and causality of the transfer function induced by this derivative. Hence, causality of the system is investigated; its output is an electromagnetic signal propagating in media described by the time-domain two-sided fractional derivative. It is demonstrated that, for the derivative order in the range [1,+∞), the transfer function describing attenuated signal propagation is not causal for any value of the asymmetry parameter of the derivative. On the other hand, it is shown that, for derivative orders in the range (0,1), the transfer function is causal if and only if the asymmetry parameter is equal to certain specific values corresponding to the left-sided Grünwald–Letnikov derivative. The results are illustrated by numerical simulations and analyses. Some comments on the Kramers–Krönig relations for logarithm of the transfer function are presented as well.

  • Significant Production of Thermal Energy in Partially Ionized Hyperbolic Tangent Material Based on Ternary Hybrid Nanomaterials
    • Umar Nazir
    • Muhammas Sohail
    • Muhammad Bilal Hafeez
    • Marek Krawczuk
    2021 Full text ENERGIES

    Nanoparticles are frequently used to enhance the thermal performance of numerous materials. This study has many practical applications for activities that have to minimize losses of energy due to several impacts. This study investigates the inclusion of ternary hybrid nanoparticles in a partially ionized hyperbolic tangent liquid passed over a stretched melting surface. The fluid motion equation is presented by considering the rotation effect. The thermal energy expression is derived by the contribution of Joule heat and viscous dissipation. Flow equations were modeled by using the concept of boundary layer theory, which occurs in the form of a coupled system of partial differential equations (PDEs). To reduce the complexity, the derived PDEs (partial differential equations) were transformed into a set of ordinary differential equations (ODEs) by engaging in similarity transformations. Afterwards, the converted ODEs were handled via a finite element procedure. The utilization and effectiveness of the methodology are demonstrated by listing the mesh-free survey and comparative analysis. Several important graphs were prepared to show the contribution of emerging parameters on fluid velocity and temperature profile. The findings show that the finite element method is a powerful tool for handling the complex coupled ordinary differential equation system, arising in fluid mechanics and other related dissipation applications in applied science. Furthermore, enhancements in the Forchheimer parameter and the Weissenberg number are necessary to control the fluid velocity

  • Similarities and differences in the production of renewable energy in Central and Eastern Europe countries
    • Agnieszka Wałachowska
    2021

    Research background: In the era of climate change, environmental degradation, but also growing pub-lic awareness, there is a need to look for new ecological energy sources. This condition can be met by renewable energy sources (RES). The EU seeks to have a 32% share of its gross final energy consumption from renewable sources by 2030. While the EU as a whole is on course to meet its tar-gets, the question is if production of renewable energy at a given level is not a chal-lenge for selected Central and Eastern Europe countries (CEECs) trsdi-tionslly dependent on fossil fuels. In order to take steps to develop RES in the studied countries, there is a need to analyze their diversity in terms of the potential. The results of such analyses should support the implementation of adopted strate-gies. Purpose of the article: The article divides the CEECs into similar groups by the structure and volume of energy production from RES. This production was com-pared with the value of Gross Domestic Product (GDP) of each studied country, the number of in-habitants and its area. Methods: Cluster analysis. The research based on the data provided by Euro-stat. Findings & Value added: The division of the studied region into subgroups de-pends on how the RES energy production is related to the GDP value, the number of inhabitants and the area of individual country. This reference allows to reflect the specificity of individual countries in more appropriate way than just an analysis of the absolute values of this production. The applied approach allows for a broad-er look at RES production for selected countries in the region. The obtained results can be used for the development of a common energy and climate policy to create and develop their own renewable energy markets.

  • Simple 60 GHz Switched Beam Antenna for 5G Millimeter-Wave Applications
    • Kamil Trzebiatowski
    • Mateusz Rzymowski
    • Łukasz Kulas
    • Krzysztof Nyka
    2021 Full text IEEE Antennas and Wireless Propagation Letters

    A new 60 GHz band single-input switched beam antenna is proposed for the fifth-generation (5G) millimeter-wave network applications. The presented design is capable of electronically switching the main beam in two different directions via a proposed microstrip-line-to-slotline single-pole dual-throw (SPDT) switch based on commercially available p-i-n diodes. The antenna is fabricated in a low-cost printed circuit board process on a CuClad 217 substrate. Measurements were carried out in an anechoic chamber and experimental results show good agreement with numerical simulations. The antenna is capable of switching the main beam to the +45 $^\circ$ and −45 $^\circ$ directions in the horizontal plane with a gain of about 3 dBi and a beamwidth of 80 $^\circ$ in both states. The presented prototype shows several advantages over other state-of-the-art millimeter-wave reconfigurable antennas such as a simple electrical switching mechanism, low-cost manufacturing, a low profile, and a small footprint. These features make the presented antenna ideal for low-cost millimeter-wave 5G applications, particularly in end-devices working under the Internet-of-Things paradigm.

  • Simple SIR models with Markovian control
    • Krzysztof Bartoszek
    • Wojciech Bartoszek
    • Michał Krzemiński
    2021 Full text Japanese journal of statistics and data science

    We consider a random dynamical system, where the deterministic dynamics are driven by a finite-state space Markov chain. We provide a comprehensive introduction to the required mathematical apparatus and then turn to a special focus on the susceptible-infected-recovered epidemiological model with random steering. Through simulations we visualize the behaviour of the system and the effect of the high-frequency limit of the driving Markov chain. We formulate some questions and conjectures of a purely theoretical nature.

  • Simple sufficient condition for subspace to be completely or genuinely entangled
    • Maciej Demianowicz
    • Grzegorz Rajchel-Mieldzioć
    • Remigiusz Augusiak
    2021 Full text NEW JOURNAL OF PHYSICS

    We introduce a simple sufficient criterion, which allows one to tell whether a subspace of a bipartite or multipartite Hilbert space is entangled. The main ingredient of our criterion is a bound on the minimal entanglement of a subspace in terms of entanglement of vectors spanning that subspace expressed for geometrical measures of entanglement. The criterion is applicable to both completely and genuinely entangled subspaces. We explore its usefulness in several important scenarios. Further, an entanglement criterion for mixed states following directly from the condition is stated. As an auxiliary result we provide a formula for the generalized geometric measure of entanglement of the $d$--level Dicke states.

  • Simplified approach to assess the dynamic response of a container ship subjected to bow slamming load
    • Krzysztof Wołoszyk
    • Marian Bogdaniuk
    2021 Full text

    Simplified approach to assess the dynamic response of a container ship subjected to the bow slamming load, resulting in a transient vibratory response, typically called a 'whip-ping', is presented. The accurate numerical modelling is very complex and involves cou-pling of the hydrodynamic and structural solution at every time step, leading to huge com-putational and workload cost. Thus, the one-way coupling methodology is adopted, and hydrodynamic loads are derived using linear strip theory in the first step and applied to the FE beam model. Structural response is obtained in the time domain using an explicit dy-namic solver. Extreme bending moment is derived and compared with the normative val-ues of the wave-induced bending moment. Comparing to more accurate methods, the pre-sented approach seems to overestimate the bending moment and leads to a conservative design. Thus, it may be used in the early stages of the design, where fast and reliable methods are essential.

  • Simplified Method of Modelling Behaviour of Ship in Waves with Partially Flooded Compartments
    • Peter Szulczewski
    2021 Full text Transactions on Maritime Science-ToMS

    This paper contains a description of a numerical model for calculating behaviour of ships in waves. There are many models available, but the one described here can be characterised with a set of parameters that have a decisive impact on the final values of roll motion amplitude and frequency. In this paper, it is shown how a fitting of a standard-shape hull characterised by certain readily available parameters affects the final roll and frequency of the motion. In addition, calculations for a flooded tank were made, and a range of results for the maximum dynamic heeling forces from this tank is shown. This calculation can further be verified for a range of hull dimensions and geometries to present a viable method to the industry.

  • Simulation investigation of perovskite-based solar cells
    • Maciej Łuszczek
    • Grzegorz Łuszczek
    • Dariusz Świsulski
    2021 Full text Przegląd Elektrotechniczny

    Three models of thin-layer lead-halide perovskite solar cells with different electron-transport layers (TiO2,SnO2,ZnO) were investigatedby the simulation method. The perovskite layer thickness was optimized for all the systems. The analysis of the standard photovoltaic cell performanceparameters at various operating temperatures was performed. The best performance was achieved for the system with theSnO2conductive layer.