2022 - Repozytorium publikacji - Politechnika Gdańska

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ON DYNAMICS OF ELASTIC NETWORKS WITH RIGID JUNCTIONS WITHIN NONLINEAR MICRO-POLAR ELASTICITY
- Victor Eremeev
- Emanuele Reccia
2022 Pełny tekst International Journal for Multiscale Computational Engineering
Within the nonlinear micropolar elasticity we discuss effective dynamic (kinetic) properties of elastic networks with rigid joints. The model of a hyperelastic micropolar continuum is based on two constitutive relations, i.e., static and kinetic ones. They introduce a strain energy density and a kinetic energy density, respectively. Here we consider a three-dimensional elastic network made of three families of elastic fibers connected through massive rigid joints. Effective elastic properties are inherited from the geometry and material properties of the fibers, whereas the kinetic (inertia) properties are determined by the both fibers and joints. Formulae for microinertia tensors are given.
On Earth as in Universe
- Krzysztof Wróblewski
2022
On Earth as in Universe Ślady zostawione na podobraziu przygotowanym własnoręcznie przez Kazimierza Ostrowskiego. Kilka pociągnięć pędzlem ciemną farbą na odwrocie płótna, tu i ówdzie przyklejone włosy do powierzchni gruntu, kurz nagromadzony przez lata - słowem każdy element artefaktu, który trafił do mnie, był kapsułą czasu sprzed około pięćdziesięciu lat. Jedyne co mogłem zrobić, to wpisać drobiny obecności Kazimierza Ostrowskiego w strukturę malowanego obrazu. Odnosząc się luźno do twórczości Kacha użyłem dwóch przetworzonych wzorów opracowanych przez Rogera Penrose'a. Ich bazą są symetrie pięcioosiowe wynikające ze złotego podziału. Zarówno na Ziemi jak i w Kosmosie panuje matematyczny porządek, choć na co dzień tego nie dostrzegamy. Na początku XVII wieku mówił o tym Johanes Kepler w Harmonices Mundi twierdząc, że geometryczne obiekty są modelami całego świata. Ówczesne obserwacje i wnioski Keplera potwierdzają współczesne badania, według których gdy weźmiemy dwie planety z Układu Słonecznego, połączymy ich pozycje linią i będziemy na bieżąco monitorować ich wzajemne położenie, to naszym oczom ukażą się wzory o określonych regularnych kształtach. Na lewym marginesie obrazu umieściłem nawiązanie do symetrii występujących w różnych liściach. W górnym lewym rogu kompozycji znajduje się ponadto detal zaprzeczony z jednego obrazów Hilmy af Klint z cyklu zatytułowanego Ewolucja. Artystka była przekonana, że przemianę napędza zasada polaryzacji występująca w różnych formach, takich jak światło i ciemność, dobro i zło, mężczyzna i kobieta. Jej symboliczne, czy wręcz mistyczne malarstwo jest mi szczególnie bliskie. Znajduję też pewne konotacje pomiędzy dokonaniami Hilmy af Klint i Kazimierza Ostrowskiego - choć jego twórczość miała bardziej charakter alegoryczny. Malarstwo Kazimierza Ostrowskiego w moim przekonaniu spajało i monumentalizowało to, czego doświadczamy na Ziemi z tym co dzieje się we Wszechświecie. Nie opierało się ono wprawdzie na rygorystycznej geometrii, ale rządził nim intuicyjny zmysł porządku, wyczucie równowagi i harmonii. Kachu podobnie jak Lèger „dbał o płaszczyznę” a „kompozycja musiała mieć równowagę od brzegu do brzegu” . Krzysztof Wróblewski Gdańsk, 2022
On Improved-Reliability Design Optimization of High-Frequency Structures Using Local Search Algorithms
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
- Piotr Płotka
2022 Pełny tekst IEEE Access
The role of numerical optimization has been continuously growing in the design of high-frequency structures, including microwave and antenna components. At the same time, accurate evaluation of electrical characteristics necessitates full-wave electromagnetic (EM) analysis, which is CPU intensive, especially for complex systems. As rigorous optimization routines involve repetitive EM simulations, the associated cost may be significant. In the design practice, the most widely used EM-driven procedures are by far local (e.g., gradient-based) ones. While typically incurring acceptable expenses that range from dozens to a few hundreds of objective function evaluations, they are prone to failure whenever a decent initial design is not available. Representative scenarios include simulation-based size reduction of compact devices or re-design of structures for operating/material parameters being distant from those at the available design. A standard mitigation approach is the involvement of global search methods, which entails significantly higher computational costs. This paper reviews the recent methodologies introduced to improve the reliability of local parameter tuning algorithms without degrading their computational efficiency. We discuss frequency-based regularization, adaptively adjusted design specification approach, as well as accelerated feature-based optimization. All of these techniques incorporate mechanisms that improve the performance of the search process under challenging scenarios, primarily poor initial conditions. The outline of the mentioned methods is accompanied by illustrative examples including passive microwave circuits and microstrip antennas. Benchmarking against conventional local search is provided as well. Furthermore, the paper discusses the advantages and disadvantages of the reviewed frameworks as well as speculates about future research directions.
On proper (1,2)‐dominating sets in graphs
- Adrian Michalski
- Iwona Włoch
- Magda Dettlaff
- Magdalena Lemańska
2022 MATHEMATICAL METHODS IN THE APPLIED SCIENCES
In 2008, Hedetniemi et al. introduced the concept of (1,)-domination and obtained some interesting results for (1,2) -domination. Obviously every (1,1) -dominating set of a graph (known as 2-dominating set) is (1,2) -dominating; to distinguish these concepts, we define a proper (1,2) -dominating set of a graph as follows: a subset is a proper (1,2) -dominating set of a graph if is (1,2) -dominating and it is not a (1,1) -dominating set of a graph. In particular, we introduce proper (1,2) -domination parameters and study their relations with (1,2) -domination parameters and the classical domination numbers.
On reliability assessment of ship machinery system in different autonomy degree; A Bayesian-based approach
- Ahmad BahooToroody
- Mohammad Mahdi Abaei
- Osiris Valdez Banda
- Jakub Montewka
- Pentti Kujala
2022 Pełny tekst OCEAN ENGINEERING
Analyzing the reliability of autonomous ships has recently attracted attention mainly due to epistemic uncertainty (lack of knowledge) integrated with automatic operations in the maritime sector. The advent of new random failures with unrecognized failure patterns in autonomous ship operations requires a comprehensive reliability assessment specifically aiming at estimating the time in which the ship can be trusted to be left unattended. While the reliability concept is touched upon well through the literature, the operational trustworthiness needs more elaboration to be established for system safety, especially within the maritime sector. Accordingly, in this paper, a probabilistic approach has been established to estimate the trusted operational time of the ship machinery system through different autonomy degrees. The uncertainty associated with ship operation has been quantified using Markov Chain Monte-Carlo simulation from likelihood function in Bayesian inference. To verify the developed framework, a practical example of a machinery plant used in typical short sea merchant ships is taken into account. This study can be exploited by asset managers to estimate the time in which the ship can be left unattended.
On solvability of initial boundary-value problems of micropolar elastic shells with rigid inclusions
- Victor Eremeev
- Leonid Lebedev
- Violetta Konopińska-Zmysłowska
2022 Pełny tekst MATHEMATICS AND MECHANICS OF SOLIDS
The problem of dynamics of a linear micropolar shell with a finite set of rigid inclusions is considered. The equations of motion consist of the system of partial differential equations (PDEs) describing small deformations of an elastic shell and ordinary differential equations (ODEs) describing the motions of inclusions. Few types of the contact of the shell with inclusions are considered. The weak setup of the problem is formulated and studied. It is proved a theorem of existence and uniqueness of a weak solution for the problem under consideration.
On the Bending of Multilayered Plates Considering Surface Viscoelasticity
- Victor Eremeev
- Violetta Konopińska-Zmysłowska
2022
We discuss the bending resistance of multilayered plates taking into account surface/interfacial viscoelasticity. Within the linear surface viscoelasticity we introduce the surface/interfacial stresses linearly dependent on the history of surface strains. In order to underline the surface viscoelasticity contribution to the bending response we restrict ourselves to the elastic behaviour in the bulk. Using the correspondence principle of the theory of viscoelasticity we present an effective bending relaxation function.
On the deformation and frequency analyses of SARS-CoV-2 at nanoscale
- Shahriar Dastjerdi
- Mohammad Malikan
- Bekir Akgöz
- Ömer Civalek
- Tomasz Wiczenbach
- Victor Eremeev
2022 Pełny tekst INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
The SARS-CoV-2 virus, which has emerged as a Covid-19 pandemic, has had the most significant impact on people's health, economy, and lifestyle around the world today. In the present study, the SARS-CoV-2 virus is mechanically simulated to obtain its deformation and natural frequencies. The virus under analysis is modeled on a viscoelastic spherical structure. The theory of shell structures in mechanics is used to derive the governing equations. Whereas the virus has nanometric size, using classical theories may give incorrect results. Consequently, the nonlocal elasticity theory is used to consider the effect of interatomic forces on the results. From the mechanical point of view, if a structure vibrates with a natural frequency specific to it, the resonance phenomenon will occur in that structure, leading to the destruction of the structure. Therefore, it is possible that the protein chains of SARS-CoV-2 would be destroyed by vibrating it at natural frequencies. Since the mechanical properties of SARS-CoV-2 are not clearly known due to the new emergence of this virus, deformation and natural frequencies are obtained in a specific interval. Researchers could also use this investigation as a pioneering study to find a non-vaccine treatment solution for the SARS-CoV-2 virus and various viruses, including HIV.
On the differential effect of temperature on the Nusselt-Rayleigh relationship in free convection
- Michał Ryms
- Grzegorz J. Kwiatkowski
- Witold Lewandowski
2022 INTERNATIONAL JOURNAL OF THERMAL SCIENCES
The aim of and inspiration behind this paper was to explain the reasons, also observed by other researchers, of the discrepancy in the results of experimental free convection, which for small Rayleigh and Nusselt numbers in the initial phase of research can sometimes reach several hundred percent. These discrepancies decrease with increasing heating power and plate surface temperature, in proportion to the increase in Ra and Nu, reaching typical values for this type of research. To explain this phenomenon, a comprehensive theoretical and experimental analysis of the influence of the physical properties of a fluid (air and water) as well as primary (tw and t∞) and secondary (tav and Δt) temperatures on the Rayleigh number was carried out. The impact was found to be unequal. The plate temperature tw is of greater importance, which is much higher than the much lower and almost constant temperature t∞ of the undisturbed area, especially since it causes convective movement, generating differences in fluid density and thus driving the phenomenon. Similarly, the direct contribution of the temperature difference Δt to Ra suggests that it has a greater influence on convective heat transfer than the average temperature of the medium tav. By analysing the effect of each of these temperatures separately, it was possible to show that their mutual, compatible or opposite interaction (tw/t∞) causes a different scattering of results, or may even lead to unusual Rayleigh numbers (Ra temperature dualism). This study led not only to a better understanding of the phenomenon, but even to a prediction of its unusual behaviour, unheard of in typical experimental studies of free convection. For example, if we consider the theoretical convective heat transfer from a plate l = 0.15 m in air in the context of the interaction of tav and Δt, it turns out that for the same Δt = 40 K, the Rayleigh number may assume, depending on tav = (tw + t∞)/2, different values. So, for tw = 50 °C, t∞ = 10 °C and tav = 30 °C, Ra = 1.213.107, whereas for tw = 90 °C, t∞ = 50 °C and tav = 70 °C it is ≈ 1.7 times smaller (Ra = 0.687.107). This hypothetical phenomenon, unheard of in typical experimental studies, which could occur, and maybe even does occur in smelting, thermal energy, etc., forces us to think about the values of Nusselt numbers, heat transfer coefficients and heat fluxes for these two cases. This lies beyond the scope of the present paper, but it is a topic for possible future research.
On the Role of Polarimetric Decomposition and Speckle Filtering Methods for C-Band SAR Wetland Classification Purposes
- Monika Gierszewska
- Tomasz Berezowski
2022 Pełny tekst IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Previous wetlands studies have thoroughly verified the usefulness of data from synthetic aperture radar (SAR) sensors in various acquisition modes. However, the effect of the processing parameters in wetland classification remains poorly explored. In this study, we investigated the influence of speckle filters and decomposition methods with different combinations of filter and decomposition windows sizes on classification accuracy. We used a C-band Radarsat 2 image acquired over a wetland located in northeast Poland. We processed the SAR data using various speckle filters: boxcar, intensity-driven adaptive-neighborhood (IDAN), improved Lee sigma, refined Lee (in 5×5 to 11×11 pixel window sizes), and a nonlocal NL-SAR. Next, we processed the nonfiltered and filtered data using nine polarimetric decompositions, also in 5×5 to 11×11 pixel window sizes. The extracted polarimetric features were applied as an input dataset in the random forest classification model in single- and multidecomposition scenarios. In the single-decomposition scenario, the Cloude–Pottier decomposition produced the highest (72%) and the Touzi decomposition achieved the lowest (38%) accuracy. The IDAN filter with an 11×11 filter window and a 9×9 decomposition window had the highest, and the nonfiltered data with a 5×5 decomposition window had the lowest accuracy in the multidecomposition scenario. The most important features were the alpha parameter from the Cloude–Pottier decomposition, the polarimetric contribution of the Shannon entropy, and the volume backscattering components. The results stress the importance of appropriate processing parameters in the SAR data classification workflow, and the study guides in selecting the most suitable combination of radar image processing parameters for wetland classification.
On the Use of Selected 4th Generation Nuclear Reactors in Marine Power Plants
- Marta Drosińska-Komor
- Jerzy Głuch
- Łukasz Breńkacz
- Paweł Ziółkowski
2022 Pełny tekst Polish Maritime Research
This article provides a review of the possibility of using different types of reactors to power ships. The analyses were carried out for three different large vessels: a container ship, a liquid gas carrier and a bulk carrier. A novelty of this work is the analysis of the proposal to adapt marine power plants to ecological requirements in shipping by replacing the conventional propulsion system based on internal combustion engines with nuclear propulsion. The subjects of comparison are primarily the dimensions of the most important devices of the nuclear power plant and the preliminary fitness analysis. It was assumed for this purpose that the nuclear power plant fits in the engine room compartment and uses the space left after the removal of the combustion engines. At the same time, this propulsion provides at all times sufficient energy for port, technological and shipping operations at an economically justifiable speed. For deep-sea vessels, which are supposed to reach null emissions of CO, CO2, NOx, SOx and H2O, this is one of the most reasonable solutions. Finally the paper proves that all the above-mentioned marine functions could be effectively applied in power plants equipped with 4th generation nuclear reactors.
On the use of the cumulative strain energy density for fatigue life assessment in advanced high-strength steels
- Ricardo Branco
- Rui F. Martins
- José A.F.O. Correia
- Zbigniew Marciniak
- Wojciech Macek
- J. Jesus
2022 Pełny tekst INTERNATIONAL JOURNAL OF FATIGUE
In this paper, the applicability of the cumulative strain energy density is explored as a fatigue indicator parameter for advanced high-strength steels subjected to strain-controlled conditions. Firstly, the cyclic stress-strain responses of nine steels, selected from three multiphase families, encompassing different elemental compositions and different heat treatment routes, were studied. Then, the predictive capabilities of the proposed model were compared to those of other strain-based and energy-based approaches. It was found that the cumulative strain energy density decreases as the strain amplitude rises and it can be correlated with the fatigue life via a power function. In addition, the dialectical relationship between the cumulative strain energy and the fatigue life was not significantly affected by the elemental composition or the heat treatment route. Furthermore, the fatigue lives computed through the cumulative strain energy density concept were close to those of the other models but were slightly more conservative.
On weak solutions of the boundary value problem within linear dilatational strain gradient elasticity for polyhedral Lipschitz domains
- Victor Eremeev
- Francesco dell'Isola
2022 Pełny tekst MATHEMATICS AND MECHANICS OF SOLIDS
We provide the proof of an existence and uniqueness theorem for weak solutions of the equilibrium problem in linear dilatational strain gradient elasticity for bodies occupying, in the reference configuration, Lipschitz domains with edges. The considered elastic model belongs to the class of so-called incomplete strain gradient continua whose potential energy density depends quadratically on linear strains and on the gradient of dilatation only. Such a model has many applications, e.g., to describe phenomena of interest in poroelasticity or in some situations where media with scalar microstructure are necessary. We present an extension of the previous results by Eremeyev et al. (2020 Z angew Math Phys 71(6): 1–16) to the case of domains with edges and when external line forces are applied. Let us note that the interest paid to Lipschitz polyhedra-type domains is at least twofold. First, it is known that geometrical singularity of the boundary may essentially influence singularity of solutions. On the other hand, the analysis of weak solutions in polyhedral domains is of great significance for design of optimal computations using a finite-element method and for the analysis of convergence of numerical solutions.
On zero-error codes produced by greedy algorithms
- Marcin Jurkiewicz
2022 Pełny tekst JOURNAL OF COMBINATORIAL OPTIMIZATION
We present two greedy algorithms that determine zero-error codes and lower bounds on the zero-error capacity. These algorithms have many advantages, e.g., they do not store a whole product graph in a computer memory and they use the so-called distributions in all dimensions to get better approximations of the zero-error capacity. We also show an additional application of our algorithms.
Online Volatile Compound Emissions Analysis Using a Microchamber/Thermal Extractor Coupled to Proton Transfer Reaction-Mass Spectrometry
- Y Lan Pham
- Wojciech Wojnowski
- Jonathan Beauchamp
2022 Pełny tekst ANALYTICAL CHEMISTRY
Indoor air is a complex and dynamic mixture comprising manifold volatile organic compounds (VOCs) that may cause physiological and/or psychological discomfort, depending on the nature of exposure. This technical note presents a novel approach to analyze VOC emissions by coupling a microchamber/thermal extractor (μ-CTE) system to a proton transfer reaction-mass spectrometer (PTR-MS). This configuration provides an alternative to conventional emissions testing of small objects. The dynamic emission profiles of VOCs from a representative 3D-printed model are presented as a proof-of-concept analysis. Emission profiles are related to the target compound volatility, whereby 2-propanol and acetaldehyde exhibited the highest emissions and most rapid changes compared to the less volatile vinyl crotonate, 2-hydroxymethyl methacrylate, and mesitaldehyde, which were present at lower concentrations and showed different dynamics. Comparative measurements of the emission profiles of these compounds either with or without prior static equilibration yielded stark differences in their dynamics, albeit converging to similar values after 15 min of sampling time. Further, the utility of this system to determine the time required to capture a specific proportion of volatile emissions over the sampling period was demonstrated, with a mean duration of 8.4 ± 0.3 min to sample 50% of emissions across all compounds. This novel configuration provides a means to characterize the dynamic nature of VOC emissions from small objects and is especially suited to measuring highly volatile compounds, which can present a challenge for conventional sampling and analysis approaches. Further, it represents an opportunity for rapid, targeted emissions analyses of products to screen for potentially harmful volatiles.
Open-Set Speaker Identification Using Closed-Set Pretrained Embeddings
- Michał Affek
- Marek Tatara
2022 Pełny tekst
The paper proposes an approach for extending deep neural networks-based solutions to closed-set speaker identification toward the open-set problem. The idea is built on the characteristics of deep neural networks trained for the classification tasks, where there is a layer consisting of a set of deep features extracted from the analyzed inputs. By extracting this vector and performing anomaly detection against the set of known speakers, new speakers can be detected and modeled for further re-identification. The approach is tested on the basis of NeMo toolkit with SpeakerNet architecture. The algorithm is shown to be working with multiple new speakers introduced.
Opracowanie deskryptora nawierzchni drogowej do oceny oporu toczenia opon samochodowych
- Sławomir Sommer
2022 Pełny tekst
Na początku niniejszej pracy pt. „Opracowanie deskryptora nawierzchni drogowej do oceny oporu toczenia opon samochodowych” przedstawiono zagadnienia dotyczące oporów ruchu pojazdu. Omówiono metody zarówno drogowe, jak i laboratoryjne badań oporu toczenia opon samochodowych. Zaprezentowano przykładowe wartości współczynników oporu toczenia opon na różnych rodzajach nawierzchni. Kolejno omówiono metody pomiaru tekstury nawierzchni. W dalszej części przedstawiono obowiązującą procedurę określania średniej głębokości profilu (Mean Profile Depth- MPD) wykonywaną zgodnie z normą ISO 13473-1. Przedstawiono wpływ tekstury nawierzchni na opór toczenia opon samochodowych. W pracy doktorskiej wykazano, że parametr MPD źle koreluje się ze współczynnikiem oporu toczenia opon. W celu przeprowadzenia analiz tekstur nawierzchni opracowano autorskie stanowiska badawcze: do pomiaru profilu tekstur nawierzchni oraz wykonanych na nich odcisków opon, a także do pomiaru sztywności dynamicznej bieżnika opony w warunkach penetracji przez elementy tekstury nawierzchni. Przeanalizowano szereg parametrów geometrycznych związanych z teksturą nawierzchni w aspekcie oporu toczenia. W efekcie opracowano parametr Descriptor of Pavament Texture (DPT50), który lepiej niż MPD koreluje się z oporem toczenia. W dalszej części przedstawiono model matematyczny opisujący ten parametr. W wyniku przeprowadzonych analiz opracowano wzorcową nawierzchnię, która ma posłużyć do prowadzenia normatywnych badań opon w warunkach laboratoryjnych. Na zakończenie pracy przedstawiono autorską technologię wytwarzania replik nawierzchni rzeczywistych, jak i wzorcowych przeznaczonych do pokrywania stalowych bębnów maszyn bieżnych.
Opracowanie technologii naprawy nieciągłości metalicznych w połączeniach spawanych, w konstrukcji podpór przednich pras filtracyjnych położonych na terenie Grupowej Oczyszczalni Ścieków Dębogórze
- Wojciech Kiełczyński
- Kamil Wilk
- Maciej Kiełczyński
2022
Celem niniejszej pracy jest opracowanie wytycznych technologicznych, których wdrożenie pozwoli na usunięcie istniejących pęknięć, co przyczyni się do stabilizacji wymiarowej podpór oraz całej konstrukcji pras. Osiągniecie tego celu wymaga podjęcia następujących działań: - ocenę stanu technicznego naprawianego komponentu- podpór przednich trzech pras filtracyjnych, - określenie własności spawalniczych materiału naprawianego, - określenie warunków eksploatacji i wymogów dotyczących spawania, - zdeterminowanie norm i przepisów dedykowanych naprawianej konstrukcji, - opracowania zaleceń i wytycznych do opisu procedur spawalniczych, - kwalifikacji procedur – czyli oceny jakości spoin próbnych, - opracowanie procedur kontroli jakości na poszczególnych etapach realizacji naprawy, - sporządzenie dokumentacji końcowej.
Optimal placement of IMU sensor for the detection of children activity
- Magdalena Madej
- Jacek Rumiński
2022
In this paper an investigation to determine the optimal placement of IMU sensors for the purpose of children characteristic activity detection is presented. The article compares four different placement of two IMU sensors on human body. Ten healthy volunteers participated within the study. Data were collected firstly from two wireless 9-axial IMU sensors placed at the left and right wrists, then sensors were placed at lower back and hip (dominant hand side). Activities included jumping, rotating, walking, walking on tiptoe, running, clapping hands, standing still, sitting still and dancing. Several parameters such as mean, standard deviation, skewness, kurtosis, energy, correlations, Hjorth parameters (activity, mobility and complexity) and spectra purity index, were calculated from measured data. Data from all locations provided similar levels of accuracy in differentiate analyzed activities.
Optimal reshaping and stress controlling of double-layer spherical structures under vertical loadings
- Ahmed Manguri
- Najmadeen Saeed
- Aram Mahmood
- Javad Katebi
- Robert Jankowski
2022 Pełny tekst Archives of Civil Engineering
Optimal reshaping and stress controlling of double-layer spherical structures under vertical loadings