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Gdańsk University of Technology

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Publications from the year 2024

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  • Mobilenet-V2 Enhanced Parkinson's Disease Prediction with Hybrid Data Integration
    • Sameer Ahmad Bhat
    • Piotr Szczuko
    2024 Full text

    This study investigates the role of deep learning models, particularly MobileNet-v2, in Parkinson's Disease (PD) detection through handwriting spiral analysis. Handwriting difficulties often signal early signs of PD, necessitating early detection tools due to potential impacts on patients' work capacities. The study utilizes a three-fold approach, including data augmentation, algorithm development for simulated PD image datasets, and the creation of a hybrid dataset. MobileNet-v2 is trained on these datasets, revealing higher generalization or prediction accuracy of 84% with hybrid datasets. Future research will explore the impact of high variability synthetic datasets on prediction accuracies and investigate the MobileNet-v2 architecture's memory footprint for timely inferences with low latency

  • Modal modification of structural damping applied to increase the stability and convergence of numerical integration
    • Krzysztof Lipiński
    2024

    The presented paper refers to numerical tests done on systems fused of multibody and finite-element parts. The appearance of its multibody part gives rise to significant nonlinear components, i.e., second-order nonlinear differential equations express the dynamics. We usually solve these equations by “step-by-step” integration methods. When using the currently available integration algorithms, we approximate these initial systems of equations by their associated sets of difference equations. The resulting approximated answers enclose superfluous solutions not related to the true one. Calculation that does not magnify these approximation errors is called numerically stable. The initial task is to find robust algorithms, i.e., such that do not produce extraordinarily different results for tiny changes in the initial data. We should underline that numerical instability is a phenomenon due to the employed numerical method but not due to the problem itself. We apply a modal modification of the damping matrix to eliminate these instabilities. The idea of modal modification is not a novelty. We should recall the modal reduction of system degrees of freedom as the example (suppression of its highest damped modes). With the Author's proposition, we do not eliminate these modes but reduce their damping to correlate them with the user-optimal time step. The highest damped modes of the resulting model diminish slower but still under the supposition of vanishing in a period lower than the assumed interval of the observations.

  • Model Management for Low-Computational-Budget Simulation-Based Optimization of Antenna Structures Using Nature-Inspired Algorithms
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2024 APPLIED SOFT COMPUTING

    The primary objective of this study is investigation of the possibilities of accelerating nature-inspired optimization of antenna structures using multi-fidelity EM simulation models. The primary methodology developed to achieve acceleration is a model management scheme which the level of EM simulation fidelity using two criteria: the convergence status of the optimization algorithm, and relative quality of the individual designs within the solution pool. The search process is initiated using the lowest-fidelity (therefore, the fastest) EM model. The fidelity is step-by-step increased towards the conclusion of the process. At the same time, lower-quality designs are evaluated at lower resolution level as compared to the better ones. Our technique has been extensively validated using several microstrip antennas, and particle swarm optimization (PSO) algorithm as the search engine. The obtained results demonstrate that making the EM model fidelity dependent on just the convergence status of the algorithm allows for relative savings from forty to seventy percent, depending on the algorithm setup. At the same time, managing model fidelity as a function of both convergence status and relative design quality (within the population processed by the algorithm) allows for up to 85 percent savings, as compared to high-fidelity-based algorithms. Furthermore, the achieved acceleration is not detrimental to the optimization process reliability. Apart from the computational efficiency, the attractive feature of the proposed approach is implementation simplicity and versatility: the presented management scheme can be readily incorporated into most nature-inspired routines.

  • Model oceny dojrzałości przedsiębiorstw do zastosowania zwinnych metodyk zarządzania projektami IT
    • Piotr Zejer
    2024 Full text

    Dysertacja koncentruje się na budowie modelu, który ocenia gotowość przedsiębiorstw do wdrożenia zwinnych metodyk zarządzania projektami IT. Analizuje istniejące metody oceny dojrzałości projektowej i wprowadza własny model, biorąc pod uwagę krytyczne czynniki sukcesu i skuteczność zwinnych metod. Rozprawa zawiera badania literaturowe, empiryczne studium przypadku oraz weryfikację i rekomendacje modelu, dostarczając wglądu w praktyczne zastosowanie zwinnych metod zarządzania projektami w sektorze IT. Głównym celem modelu jest wskazanie uwarunkowań i obszarów funkcjonalnych przedsiębiorstwa, które wymagają poprawy dla skutecznego stosowania tych metod. Praca dostarcza praktycznego narzędzia dla organizacji, umożliwiającego ocenę ich dojrzałości w kontekście zwinnych praktyk zarządzania projektami, co ma kluczowe znaczenie dla sukcesu projektów IT w dynamicznie zmieniającym się środowisku biznesowym.

  • Model Pomorskiej Nagrody Jakości w świetle wyników badań opinii stron zainteresowanych
    • Anna Wendt
    • Piotr Grudowski
    2024 Problemy Jakości

    Cel - prezentacja oryginalnego modelu wykorzystywanego do oceny/samooceny organizacji w regionalnym konkursie o Pomorską Nagrodę Jakości na podstawie oceny dotychczasowych doświadczeń oraz badania opinii i potrzeb głównych interesariuszy tej inicjatywy. Podstawowym założeniem przy opracowaniu tego modelu jest jego dostosowanie do współczesnych trendów dotyczących doskonałości organizacyjnej oraz upowszechnienie jego stosowania jako obiektywnej podstawy ewaluacji skuteczności i efektywności organizacji prywatnych i publicznych. Projekt badania, metodyka badawcza, koncepcja - na podstawie integracyjnego przeglądu literatury określono cel opracowania. Dla osiągnięcia tego celu przeprowadzono badania empiryczne, które wykorzystują studium przypadku (case study) konkursów o Pomorską Nagrodę Jakości. W tym kontekście zastosowano metody badań jakościowych takie jak ustrukturyzowane wywiady bezpośrednie, analizę materiałów źródłowych oraz obserwacje uczestniczące. Wyniki/ wnioski - uczestnicy konkursów pozytywnie ocenili proces organizacji konkursu. Dostrzegali jednak problemy związane z wykorzystaniem arkusza samooceny. Były to m.in. zbyt duża pracochłonność związana z wypełnianiem arkusza przez uczestników konkursu oraz niezrozumienie zawartych w nim stwierdzeń i pojęć. Uwagi te potwierdzili także organizatorzy konkursu. W związku z aktualizacją Modelu EFQM, na którego założeniach i zasadach opierały się stosowane dotąd kryteria konkursowe, postanowiono uaktualnić Model Pomorskiej Nagrody Jakości. W tym celu wykorzystano Model EFQM w wersji z roku 2020, aktualną wersję modelu CAF oraz wnioski z przeprowadzonych przez autorów badań jakościowych. Opracowano nową wersję kwestionariusza samooceny oraz dostosowano skalę ocen i punktację stanowiącą podstawę określenia wyników w konkursach. Zastosowanie praktyczne - opracowany w roku 2023 model oceny w ramach Pomorskiej Nagrody Jakości może być stosowany jako podstawa rozwoju systemu zarządzania organizacją. Ankieta samooceny jest narzędziem doskonalenia obejmującym wiele obszarów działalności organizacji. Sam udział w konkursie jest poświadczeniem wysokiego poziomu świadomości projakościowej organizacji oraz sprzyjać może wymianie dobrych praktyk na szczeblu regionalnym oraz krajowym i międzynarodowym.

  • Modeling and Accuracy Assessment of Determining the Coastline Course Using Geodetic, Photogrammetric and Satellite Measurement Methods: Case Study in Gdynia Beach in Poland
    • Francesco Giuseppe Figliomeni
    • Mariusz Specht
    • Claudio Parente
    • Cezary Specht
    • Andrzej Stateczny
    2024 Full text Electronics

    The coastal environment represents a resource from both a natural and economic point of view, but it is subject to continuous transformations due to climate change, human activities, and natural risks. Remote sensing techniques have enormous potential in monitoring coastal areas. However, one of the main tasks is accurately identifying the boundary between waterbodies such as oceans, seas, lakes or rivers, and the land surface. The aim of this research is to evaluate the accuracy of coastline extraction using different datasets. The images used come from UAV-RGB and the Landsat-9 and Sentinel-2 satellites. The method applied for extracting the coast feature involves a first phase of application of the Normalized DifferenceWater Index (NDWI), only for satellite data, and consequent application of the maximum likelihood classification, with automatic vectorization. To carry out a direct comparison with the extracted data, a coastline obtained through a field survey using a Global Navigation Satellite System (GNSS) device was used. The results are very satisfactory as they meet the minimum requirements specified by the International Hydrographic Organization (IHO) S-44. Both the UAV and the Sentinel-2 reach the maximum order, called the Exclusive order (Total Horizontal Uncertainty (THU) of 5 m with a confidence level of 95%), while the Landsat-9 falls into the Special order (THU of 10 m with a confidence level of 95%).

  • Modeling and Strength Calculations of Parts Made Using 3D Printing Technology and Mounted in a Custom-Made Lower Limb Exoskeleton
    • Szczepan Śpiewak
    • Wiktoria Wojnicz
    • Jan Awrejcewicz
    • Magdalena Mazur
    • Michał Ludwicki
    • Bartosz Stańczyk
    • Bartłomiej Zagrodny
    2024 Full text Materials

    This study is focused on the application of 3D-printed elements and conventional elements to create a prototype of a custom-made exoskeleton for lower limb rehabilitation. The 3D-printed elements were produced by using Fused Deposition Modeling technology and acrylonitrile butadiene styrene (ABS) material. The scope of this work involved the design and construction of an exoskeleton, experimental testing of the ABS material and numerical research by using the finite element method. On the basis of the obtained results, it was possible to deduce whether the load-bearing 3D-printed elements can be used in the proposed mechanical construction. The work contains full data of the material models used in FEM modeling, taking into account the orthotropic properties of the ABS material. Various types of finite elements were used in the presented FE models. The work is a comprehensive combination of material testing issues with the possibility of implementing the obtained results in numerical strength models of machine parts.

  • Modeling lignin extraction with ionic liquids using machine learning approach
    • Karol Baran
    • Beata Barczak
    • Adam Kloskowski
    2024 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    Lignin, next to cellulose, is the second most common natural biopolymer on Earth, containing a third of the organic carbon in the biosphere. For many years, lignin was perceived as waste when obtaining cellulose and hemicellulose and used as a biofuel for the production of bioenergy. However, recently, lignin has been considered a renewable raw material for the production of chemicals and materials to replace petrochemical resources. In this context, an increasing demand for high-quality lignin is to be expected. It is, therefore, essential to optimize the technological processes of obtaining it from natural sources, such as biomass. In this work, an investigation of the use of machine learning-based quantitative structure-property relationship (QSPR) modeling for the preliminary processing of lignin recovery from herbaceous biomass using ionic liquids (ILs) is described. Training of the models using experimental data collected from original publications on the topic is assumed, and molecular descriptors of the ionic liquids are used to represent structural information. The study explores the impact of both ILs' chemical structure and process parameters on the efficiency of lignin recovery from different bio sources. The findings give an insight into the extraction process and could serve as a foundation for further design of efficient and selective processes for lignin recovery using ionic liquids, which can have significant implications for producing biofuels, chemicals, and materials.

  • Modeling of free vibrations and resonant frequencies of simply-supported submerged horizontal plate
    • Justyna Slawinska-Budzich
    • Wojciech Sulisz
    • Jarosław Przewłócki
    2024 Full text PLOS ONE

    A theoretical approach was applied to study the vibration of simple-supported submerged horizontal plate. The derived analytical solution was used to determine natural frequencies for a horizontal plate vibrating in fluid. The investigations were conducted for a very wide range of material density and elasticity modulus covering all materials used in engineering practice. Analysis shows that plate vibration frequency decreases with increasing plate width and draft, and decreases with decreasing plate thickness. Moreover, the results show that a substantial effect on vibration of submerged plate has mass of water above plate. The results also show that plate vibration frequency decreases with increasing plate material density and decreases with decreasing elasticity modulus. The dominant factors affecting the vibration of the submerged plate are the plate width, the plate thickness, and elasticity modulus. For moderate and low values of elasticity modulus, vibration frequency is becoming lower than frequency of water waves. This is very important because wave frequencies overlap with the natural plate vibration frequencies, which may lead to resonance and failure of a structure. The problem is that the overlap of plate vibration frequencies and wave frequencies occurs for very wide range of wave and plate parameters. Laboratory experiments confirm theoretical results.

  • Modelling and Control of a Brushless Multiphase Doubly-Fed Induction Generator in a Stand-Alone Wind Generation System
    • Krzysztof Blecharz
    • Roland Ryndzionek
    • Filip Kutt
    2024 IEEE Access

    The development of the novel multiphase brushless doubly-fed generator system and voltage controller for stand-alone mode configuration is proposed in this paper. The generator system is based on the new machine construction with multiphase control winding and traditional three-phase power winding. The dynamic model of multiphase brushless doubly-fed generator is presented, and the control strategy for voltage amplitude and frequency is developed. The simulation and experimental results are used to validate the performance of the topology of the multi-phase brushless double-fed generator and of the control system. The tests of the generator system have been carried out for the normal operating state of the system and for the case where one of the control phase is inactive. This situation is equivalent to a failure in the power path of the control winding.

  • Modelling and simulations in time-fractional electrodynamics based on control engineering methods
    • Damian Trofimowicz
    • Tomasz Stefański
    • Jacek Gulgowski
    • Tomasz Talaśka
    2024 Communications in Nonlinear Science and Numerical Simulation

    In this paper, control engineering methods are presented with regard to modelling and simulations of signal propagation in time-fractional (TF) electrodynamics. That is, signal propagation is simulated in electromagnetic media described by Maxwell’s equations with fractional-order constitutive relations in the time domain. We demonstrate that such equations in TF electrodynamics can be considered as a continuous-time system of state-space equations in control engineering. In particular, we derive continuous-time analytical solutions based on state-transition matrices for electromagnetic-wave propagation in the TF media. Then, discrete-time zero-order-hold equivalent models are developed and their analytical solutions are derived. It is demonstrated that the proposed models give the same results as other reference methods presented in the literature. However, due to the application of finite-difference scheme, they remain more flexible in terms of the number of simulation scenarios which can be tackled.

  • Modelling of heat transfer during flow condensation of natural refrigerants under conditions of increased saturation pressure
    • Stanisław Głuch
    • Dariusz Mikielewicz
    2024 Full text Archives of Thermodynamics

    The paper presents a modified in-house model for calculating heat transfer coefficients during flow condensation, which can be applied to a variety of working fluids, but natural refrigerants in particular, at full range thermodynamic parameters with a particular focus on increased saturation pressure. The modified model is based on a strong physical basis, namely the hypothesis of analogy between the heat transfer coefficient and pressure drop in two-phase flow. The model verification is based on a consolidated database that consists of 1286 data points for 7 natural refrigerants and covers the reduced pressure range (the ratio of critical pressure and saturation pressure) from 0.1 to 0.8 for different mass velocities and diameters. The new version of the in-house model, developed earlier by Mikielewicz, was compared with 4 other mathematical models widely recommended for engineering calculations and obtained the best consistency results. The value of the mean absolute percentage error was 28.13% for the modified model, the best result among the scrutinised methods.

  • Modelling tunnelling-induced deformation in stiff soils with a hyperelastic–plastic anisotropic model
    • Marcin Cudny
    • Katarzyna Lisewska
    • Manuel Winkler
    • Thomas Marcher
    2024 Acta Geotechnica

    In this paper, the tunnelling-induced deformation in anisotropic stiff soils is analysed using FE modelling. The influence of material description is investigated rather than an advanced simulation of the tunnelling method. A new hyperelastic– plastic model is proposed to describe the anisotropic mechanical behaviour of stiff highly overconsolidated soil. This model can reproduce the superposition of variable stress-induced anisotropy and constant inherent cross-anisotropy of the small strain stiffness. Additionally, a Brick-type framework accounts for the strain degradation of stiffness. Formulation of the novel model is presented. The tunnelling-induced deformation is first investigated in plane strain conditions for a simple boundary value problem of homogeneous ground. The influence of initial stress anisotropy and inherent cross- anisotropy is inspected. Later, the results of 2D simulations are compared with the analogous results of 3D simulations considering different excavated length of the tunnel sections. The tunnelling process is reproduced by introduction of a supported excavation and a lining contraction stage in undrained conditions. Finally, the tunnelling case study at St James Park is back analysed using the proposed material model in plane strain conditions. The obtained calculation results are compared with the field measurements and discussed.

  • Modelowanie dokładności radiolokalizowania w różnych warunkach środowiskowych przy wykorzystaniu interfejsu radiowego 5G-NR
    • Piotr Rajchowski
    • Luis M. Correia
    • Krzysztof Cwalina
    2024 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    W artykule przedstawiono wyniki eksperymentalnych badań dokładności estymacji położenia terminala użytkownika korzystającego~z interfejsu radiowego 5G-NR. W środowisku miejskim dokonano rejestracji rzeczywistych sygnałów sieci 5G, a następnie przeprowadzono badania numeryczne. Celem było zweryfikowanie różnic dokładności estymacji położenia w trzech różnych środowiskach: wewnątrz- i zewnątrzbudynkowym oraz tzw. deep-indoor.

  • Modelowanie liczby i wielkości uszkodzeń drogowych barier ochronnych na odcinkach dróg
    • Łukasz Jeliński
    2024 Full text

    W ramach rozprawy doktorskiej podjęto problem funkcjonowania barier ochronnych, ze szczególnym uwzględnieniem częstości występowania oraz wielkości uszkodzeń barier na odcinkach dróg krajowych w Polsce. Rozpoznanie tematyki funkcjonowania barier ochronnych przy drogach, oraz identyfikacja nierozwiązanych problemów, pozwoliły na sformułowanie głównego celu pracy i celów szczegółowych. Cele te obejmują opracowanie i wdrożenie do praktyki drogowej modeli matematycznych szacowania częstości występowania oraz wielkości uszkodzeń barier ochronnych, stosowanych na dwujezdniowych drogach krajowych w Polsce. Cele rozprawy osiągnięto poprzez realizację procesu badawczego, składającego się z następujących etapów: studiów literatury, opracowania programu badań, wyboru poligonów badawczych i budowy baz danych, przeprowadzenia serii badań terenowych, poligonowych i symulacyjnych, modelowania częstości zdarzeń i wielkości uszkodzeń barier ochronnych, w zależności od najistotniejszych czynników konstrukcyjnych, drogowych, ruchowych i utrzymaniowych, badania wpływu zidentyfikowanych czynników na funkcjonowanie barier oraz opracowania polskiej metody szacowania częstości i wielkości uszkodzeń barier ochronnych na odcinkach dróg. W końcowej części pracy przedstawiono wnioski z przeprowadzonych badań i analiz, wskazano rekomendacje dotyczące wykorzystania i wdrożenia wyników badań oraz zaproponowano kierunki dalszych badań.

  • Modern control strategy of bidirectional DAB converter with consideration of control nonlinearity
    • Serafin Bachman
    • Marek Turzyński
    • Marek Jasiński
    2024 Full text Przegląd Elektrotechniczny

    This paper focuses on the control strategy for modern universal bidirectional Dual Active Bridge (DAB) converters for microgrid systems. An analysis of the converter equations was carried out, and typical problems related to the influence of dead time on the system operation were discussed. A closed control loop was developed, then tested by simulation and on a laboratory stand.

  • Modern Light Sources on the Ship
    • Romuald Maśnicki
    • Janusz Mindykowski
    • Beata Pałczyńska
    • Dawid Werner
    2024

    The paper deals with studies on light flicker in selected modern light sources used on ships. The authors present and discuss the relationship between the hostile ship environment affecting the ship light systems and the extreme working conditions of the ship's crew manifested by health problems and a reduction in their manual abilities. These limitations result from the flicker phenomena provoked by both fluorescent lamps and LED technology sources. The authors showed that the traditionally used flicker analysis based on Plt and Pst indicators is not sufficient to assess the effects related to the operation of a modern lighting system, because in addition to voltage fluctuations, the properties of the source, i.e. light intensity as an input signal, must also be taken into account. This approach based on Fi and Fp coefficients was verified experimentally using the dedicated author's setup. The presented discussion of the measurement results showed that the approach used so far to assess flicker phenomena has some weaknesses and ambiguities concerning LED technology sources.

  • Modification of gradient HPLC method for determination of small molecules' affinity to human serum albumin under column safety conditions: Robustness and chemometrics study
    • Mateusz Woziński
    • Katarzyna Greber
    • Monika Pastewska
    • Piotr Kolasiński
    • Weronika Hewelt-Belka
    • Beata Żołnowska
    • Jarosław Sławiński
    • Daniel Szulczyk
    • Wiesław Sawicki
    • Krzesimir Ciura
    2024 JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS

    In the early stages of drug discovery, beyond the biological activity screening, determining the physicochemical properties that affect the distribution of molecules in the human body is an essential step. Plasma protein binding (PPB) is one of the most important investigated endpoints. Nevertheless, the methodology for measuring %PPB is significantly less popular and standardized than other physicochemical properties, like lipophilicity. Here, we proposed how to modify protocols presented by Valko into column safety conditions and evaluated their robustness using fractional factorial design. For robustness testing, four factors were selected: column temperature, mobile phase flow rate, maximum isopropanol concentration in the mobile phase, and buffer pH. Elaborate methods have been applied for the analysis of HSA affinity for three groups of antibiotic-oriented substances that vary in chemical structure: fluoroquinolones, sulfonamides, and tetrazole derivatives. Furthermore, based on the reversed-phase chromatography the workflow of pilot studies was proposed to select molecules that have high affinity to HSA and can not be eluted from the HSA column using the concentration of organic modifier recommended by the column manufacturer

  • Modification of the Reloading Plastic Modulus in Generalized Plasticity Models for Soil by Introducing a New Equation for the Memory Parameter in Cyclic Loadings
    • Mohammad Oliaei
    • Reza Kamgar
    • Heisam Heidarzadeh
    • Robert Jankowski
    2024 Applied Sciences-Basel

    Nowadays, with the widespread supply of very powerful laboratory and computer equipment, it is expected that the analyses conducted for geotechnical problems are carried out with very high precision. Precise analyses lead to better knowledge of structures’ behavior, which, in turn, reduces the costs related to uncertainty of materials’ behavior. A precise analysis necessitates a precise knowledge and definition of the behavior of the constituent materials, which itself requires applying an appropriate constitutive model to show the behavior of materials. Constitutive models used in the generalized plasticity framework are very powerful constitutive models for the simulation of sand behavior. However, the simulation of a cyclic behavior in these models, especially the simulation of the undrained cyclic behavior, is not well-recognized. In this study, in order to eliminate the weakness of generalized constitutive models under cyclic loading, a new equation is presented to substitute the so-called coefficient of the discrete memory factor to consider the loading history in such a way that the plastic modulus is modified during reloading and, as a result, more appropriate predictions of sand behavior are obtained. The performance accuracy of the proposed coefficient was evaluated in accordance with the experimental data. Finally, the results show that after using the modification of the loading history coefficient, predictions of the constitutive model are significantly improved.

  • Modifications of silicate bioglass synthesis and composition for in vitro dissolution control: Static and dynamic assessment
    • Stefania Wolff
    • Sharafat Ali
    • Jakub Karczewski
    • Małgorzata Rutkowska
    • Hiroyo Segawa
    • Natalia Wójcik
    2024 JOURNAL OF NON-CRYSTALLINE SOLIDS

    A set of fifteen calcium-phosphate-silicate glass samples, varying in alkali, magnesium, silicon, and nitrogen content, was prepared, and their structural, thermal, and in vitro dissolution properties were analyzed. Infrared spectroscopy showed a high degree of depolymerization of the silicate network consisting mainly of Q2 and Q3 units. Thermal analysis showed that the silicon content primarily affects both the glass transition temperature and the thermal stability of the glasses. In vitro dissolution studies were conducted both in static and dynamic modes in phosphate-buffered saline. Greater weight loss was observed for materials tested in the dynamic mode than in the static mode. Ion concentration profiles determined for PBS after immersing the glasses showed the release of sodium and calcium into solutions. Subsequent studies, conducted using scanning electron microscopy, X-ray diffraction, and infrared spectroscopy showed the formation of an amorphous or crystalline layer of calcium phosphates, most likely hydroxyapatite.