2024 - Repozytorium publikacji - Politechnika Gdańska

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Migration of trace elements and radioisotopes to various fractions of solid wastes generated as a result of the sewage sludge incineration process
- Oskar Ronda
- Bartłomiej Cieślik
- Barbara Piotrowska
- Krzysztof Isajenko
- Satoki Okabayashi
- Koichi Chiba
- Motohiro Tsuboi
- Justyna Płotka-Wasylka
2024 Pełny tekst WASTE MANAGEMENT
The research was aimed at providing new knowledge in the field of chemical characteristics of solid waste generated in the process of combustion of sewage sludge in fluidized bed furnaces. The research material consisted of disposed fluidized beds (DFB), sewage sludge ash (SSA) and air pollution control residues (APC) from three Polish installations for the thermal treatment of sewage sludge. Natural radionuclides as well as anthropogenic isotope 137Cs were determined in the tested materials and the migration of a wide spectrum of trace elements to various waste fractions generated in the process of sewage sludge combustion was examined. It was observed that both radioisotopes and most of the trace elements determined accumulate in SSA and DFB, while the APC fraction contains a much smaller amount of them. The exceptions are mercury and selenium, whose volatile compounds migrate to the exhaust gas dedusting system and accumulate in the APC fraction (up to 40 mg/kg and 13 mg/kg, respectively). A potential threat from the 226Ra isotope in SSA is identified in the context of the management of this waste in the production of building materials because the typical activity of 226Ra in SSA collected from areas with very low Ra content in natural environment exceeds 1.5–6 times the activity of this isotope in conventional cement mixtures. When managing SSA and DFB, special attention should be paid to the content of metalloids such as As, B and Se, due to the high content of mobile forms of these elements in the mentioned materials.
Millimeter Wave Negative Refractive Index Metamaterial Antenna Array
- Rao Aziz
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2024 Pełny tekst Scientific Reports
In this paper, a novel negative refractive index metamaterial (NIM) is developed and characterized. The proposed metamaterial exhibits negative effective permittivity (εeffe) and negative effective permeability (µeffe) at millimeter wave frequency of 28GHz. This attractive feature is utilized to enhance the gain of a microstrip patch antenna (MPA). Two thin layers of 5  5 subwavelength unit cell array of NIM are placed above a single MPA to enhance the gain of the antenna. Each unit cell has an area of 3.4  3.4 mm2. A gain increase of 7.9dBi has been observed when using the proposed NIM as a superstrate. Furthermore, the NIM array is placed over a 2  2 array of MPAs with four ports to demonstrate versatility of the metamaterial. The total size of the 2  2 antenna array system with N-MTM is about 61.1  34  16mm3 (5.71λ  3.18λ  1.5λ, where λ is the free-space wavelength at 28 GHz). The measurement result indicate that the maximum gain of the antenna array is 13.5dBi. A gain enhancement of 7.55 dB in E-Plane and 7.25 dB in H-Plane at the resonant frequency of 28 GHz is obtained. The proposed antenna structure is suitable for 5G millimeter wave communications, in particular, for possible implementation in future millimeter wave access points and cellular base stations.
Miniaturization-Oriented Design of Spline-Parameterized UWB Antenna for In-Door Positioning Applications
- Adrian Bekasiewicz
- Tom Dhaene
- Ivo Couckuyt
- Jacek Litka
2024
Design of ultra-wideband antennas for in-door localization applications is a challenging task. It involves development of geometry that maintains appropriate balance between the size and performance. In this work, a topologically-flexible monopole has been generated using a stratified framework which embeds a gradient-based trust-region (TR) optimization algorithm in a meta-loop that gradually increases the structure dimensionality. The optimization has been performed using a composite objective function that maintains acceptable size/performance trade-off. The final design features a reflection below –10 dB within the UWB spectrum and a small footprint of only 182 mm2. The considered method has been benchmarked against a standard TR-based routine executed directly on a multi-dimensional electromagnetic model of the antenna.
Minimization of a ship's magnetic signature under external field conditions using a multi-dipole model
- Mirosław Wołoszyn
- Jarosław Tarnawski
2024 Pełny tekst Scientific Reports
The paper addresses the innovative issue of minimizing the ship's magnetic signature under any external field conditions, i.e., for arbitrary values of ambient field modulus and magnetic inclination. Varying values of the external field, depending on the current geographical location, affect only the induced part of ship's magnetization. A practical problem in minimizing the ship signature is separating permanent magnetization from induced magnetization. When the ship position changes, a signature measurement has to be made under new magnetic field conditions to update the currents in the coils. This is impractical or even difficult to do (due to the need for a measuring ground), so there is a need to predict the ship's magnetization value in arbitrary geographical location conditions based on the reference signature determined on the measuring ground. In particular, the model predicting the signatures at a new geographical location must be able to separate the two types of magnetization, as permanent magnetization is independent of external conditions. In this paper, a FEM model of the vessel is first embedded in an external field and permanent magnetization is simulated using DC coils placed inside the model. Then, using the previously developed rules for data acquisition and determination of model parameters, a multi-dipole model is synthesized in which the induced and permanent parts are separated. The multi-dipole model thus developed has been successfully confronted with the initial model in FEM environment. The separation of permanent and induced magnetization allows the latter to be scaled according to new values of the external field. In the paper, the situation of determining a signature at one geographical position and its projection onto two other positions is analyzed. Having determined the signature with a high degree of accuracy anywhere in the world, it is possible to perform classical signature minimization by determining DC currents in coils placed inside the ship's hull. The paper also analyzes the effectiveness of ship's signature minimization and the influence of ship's course on the signature value. The advantage of the method presented in this paper is an integrated approach to the issue of scaling and minimization of ship magnetic signature, which has not been presented in the literature on such a scale before.
M-integral for finite anti-plane shear of a nonlinear elastic matrix with rigid inclusions
- Victor Eremeev
- Konstantin Naumenko
2024 Pełny tekst INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
The path-independent M-integral plays an important role in analysis of solids with inhomogeneities. However, the available applications are almost limited to linear-elastic or physically non-linear power law type materials under the assumption of infinitesimal strains. In this paper we formulate the M-integral for a class of hyperelastic solids undergoing finite anti-plane shear deformation. As an application we consider the problem of rigid inclusions embedded in a Mooney–Rivlin matrix material. With the derived M-integral we compute weighted averages of the shear stress acting on the inclusion surface. Furthermore, we prove that a system of rigid inclusions can be replaced by one effective inclusion.
Missing Puzzle Pieces in Dementia Research: HCN Channels and Theta Oscillations
- Paulina Kaźmierska-Grębowska
- Maciej Jankowski
- Bruce M. MacIver
2024 Pełny tekst Aging and Disease
Increasing evidence indicates a role of hyperpolarization activated cation (HCN) channels in controlling the resting membrane potential, pacemaker activity, memory formation, sleep, and arousal. Their disfunction may be associated with the development of epilepsy and age-related memory decline. Neuronal hyperexcitability involved in epileptogenesis and EEG desynchronization occur in the course of dementia in human Alzheimer’s Disease (AD) and animal models, nevertheless the underlying ionic and cellular mechanisms of these effects are not well understood. Some suggest that theta rhythms involved in memory formation could be used as a marker of memory disturbances in the course of neurogenerative diseases, including AD. This review focusses on the interplay between hyperpolarization HCN channels, theta oscillations, memory formation and their role(s) in dementias, including AD. While individually, each of these factors have been linked to each other with strong supportive evidence, we hope here to expand this linkage to a more inclusive picture. Thus, HCN channels could provide a molecular target for developing new therapeutic agents for preventing and/or treating dementia.
Mixed, quantum-classical description of electron density transfer in the collision process
- Paweł Wojda
- Marta Łabuda
- Sergey Kshevetskii
2024 MOLECULAR PHYSICS
In this work, we investigate an ion-atom model describing the time-dependent evolution of electron density during the collision. For a S3+- H system, numerical simulations are based on classical trajectory calculations, and the electron density behaviour is described with the time-dependent Schrödinger equation. We apply the finite difference method to obtain quantitative insights into the charge transfer dynamics, providing detailed information about the spatial and temporal evolution of the collision process. The results are given for representative examples of the collision, from eV to keV range of energies, in head-on collision as well as for different values of impact parameter. A validity and precision of the proposed model and interpretation of the particle collision in terms of eigenstates are also discussed.
Mixed-use buildings as the basic unit that shapes the housing environment of smart cities of the future
- Mateusz Gerigk
2024 Środowisko Mieszkaniowe
The contemporary approach to creating the residential function is confronted with the trend of increasing the volume of buildings and expectations regarding the future urban environment focused on sustainable development. This paper presents an overview of the residential structure in the context of defined thematic scopes. Namely, it is a systemic approach to the problem of designing mixed-use buildings which create a modern residential structure in developing urban centres. The creation of smart cities from existing urban areas and newly designed centres involves comprehensively defined design guidelines. The key is the integrity and interoperability of the dynamic structure which can serve as a basis for developing new systems and/or improving the existing ones. The developed model structure for creating and maintaining the system is based on a genetic algorithm and is presented in the form of a neural network that involves the use of artificial intelligence (AI). The specific structure is intended as a tool to support supervision and decision-making in the process of designing and managing contemporary mixed-use buildings in their newly planned surroundings.
Mobilenet-V2 Enhanced Parkinson's Disease Prediction with Hybrid Data Integration
- Sameer Ahmad Bhat
- Piotr Szczuko
2024
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
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 Pełny tekst
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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 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.