2022 - Repozytorium publikacji - Politechnika Gdańska

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Stirling engines - the state of technology development and computational models
- Mariusz Furmanek
- Jacek Kropiwnicki
2022 Pełny tekst Combustion Engines
Stirling engines represent a technologically important solution in combined heat and power systems. Their use enables the achievement of over 90 percent efficiency in the management of the primary energy source with a very high durability of the device, mainly due to the lack of contact of the working gas with external factors and a very small number of mechanical components. The use of a Stirling engine may be equally important when applying renewable energy sources or waste heat from other processes. The first part of the work presents an overview of available commercial Stirling engine solutions. The second part of the work presents an overview of numerical models of Stirling engine operation, which enable the correct selection of the main geometrical features of the devices and the improvement of the structure in order to maximize efficiency or power.
Stock price reactions to an arrangement approval in restructuring proceedings – the case of Poland
- Błażej Prusak
- Marcin Potrykus
2022 Pełny tekst International Journal of Management and Economics
The study aims to empirically analyze the reaction of stock prices to the information about the conclusion and acceptance of a debtor–creditor arrangement under restructuring proceedings of companies listed on the stock exchange in Poland. The following main research hypothesis was verified: public disclosure of information about an arrangement conclusion and acceptance in restructuring proceedings results in above-average rates of return due to investments in the stocks of these entities in the short term. Three events were assessed: the public disclosure of information about the conclusion of a debtor–creditor arrangement (Event 1), its approval by a court (Event 2), and the decision becoming final (Event 3). The research method applied was the event study. Event 1 and Event 3 leads to an above-average and statistically significant increase in stock prices on the day of the event. In contrast, no statistically significant above-average rates of return accompanied Event 2.
Stocznia. Człowiek. Przemysł. Miasto
- Krzysztof Wróblewski
2022
Pierwsza kompleksowa wystawa o historii państwowego przemysłu stoczniowego w Gdańsku, ponad 150 lat dziejów miasta – od połowy XIX wieku, kiedy powstała pierwsza stocznia państwa pruskiego w Gdańsku, poprzez historię dwóch wojen światowych, Stoczni Gdańskiej w czasach komunizmu do współczesności. Wystawa opowiada z perspektywy doświadczenia przemysłu stoczniowego w Gdańsku polityczną, społeczną i kulturową historię Polski i Europy. W centrum opowieści wystawy są losy ludzi, a nie statków. Eksponaty pochodzą od niemal 40 instytucji i osób prywatnych, z Polski i zagranicy. Korzystaliśmy m.in. ze zbiorów Archiwum Państwowego w Gdańsku, PAN Biblioteki Gdańskiej, Muzeum Gdańska, Muzeum Narodowego w Gdańsku, Muzeum Stutthof w Sztutowie, Muzeum Narodowego w Szczecinie, Muzeum Zamoyskich w Kozłówce. Ekspozycja będzie także pierwszą okazją do szerszego zaprezentowania związanych z tym tematem zbiorów ECS.
Stocznia i Westerplatte - szkic
- Krzysztof Wróblewski
2022
Obraz odnosi się do dwóch miejsc historycznych w Gdańsku - Stoczni Gdańskiej oraz Westerplatte
Stosowanie wyłączników różnicowoprądowych w instalacjach fotowoltaicznych
- Stanisław Czapp
2022 INPE: Informacje o Normach i Przepisach Elektrycznych
Przedstawiono postanowienia norm odnoszące się do doboru i instalowania wyłączników różnicowoprądowych w instalacjach fotowoltaicznych. Zwrócono uwagę, że w instalacjach takich nie ma obowiązku stosowania wyłączników różnicowoprądowych. Omówiono wpływ kształtu przebiegu prądu ziemnozwarciowego ze składową stałą na próg wyzwalania tych zabezpieczeń. Podano przykładowe wartości prądów upływowych w instalacjach fotowoltaicznych i zalecenia co do znamionowego prądu różnicowego zadziałania wyłączników różnicowoprądowych.
Straightened characteristics of McKendrick-von Foerster equation
- Agnieszka Bartłomiejczyk
- Henryk Leszczyński
- Milena Matusik
2022 JOURNAL OF DIFFERENTIAL EQUATIONS
We study the McKendrick-von Foerster equation with renewal (that is the age-structured model, with total population dependent coefficient and nonlinearity). By using a change of variables, the model is then transformed to a standard age-structured model in which the total population dependent coefficient of the transport term reduces to a constant 1. We use this transformation to get existence, uniqueness of solutions of the problem in a semigroup setting. Since straight lines are more convenient in the exact and approximate solution of PDEs, we provide sufficient conditions of reducing more general equations. We give a difference scheme to find approximate solutions of the age-structured model. Finally, some numerical simulations are presented to demonstrate the convergence and stability of the difference scheme.
Strategie treningu neuronowego estymatora częstotliwości tonu krtaniowego z użyciem generatora syntetycznych samogłosek
- Marek Blok
- Jan Banaś
- Mariusz Pietrołaj
2022 Pełny tekst Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
W wielu zastosowaniach telekomunikacyjnych pojawia się problem przetwarzania lub analizy sygnału mowy, w ramach którego, często w obszarze podstawowych algorytmów, stosuje się estymator częstotliwości tonu krtaniowego. Estymator rozpatrywany w tej pracy bazuje na neuronowym klasyfikatorze podejmującym decyzje na podstawie częstotliwości oraz mocy chwilowej wyznaczanych w podpasmach analizowanego sygnału mowy. W pracy rozważamy problematykę treningu tego estymatora, gdy trening odbywa się z użyciem sygnałów generowanych syntetycznie.
Stress analysis of suspended rail vehicle bogie
- Mateusz Kuczyk
- Piotr Jędrzejewski
- Paweł Załuski
2022 Pełny tekst Pojazdy Szynowe
Niniejsza publikacja została poświęcona analizie wytrzymałościowej wybranych elementów wózka – osi zestawu kołowego i ramy. Obliczenia osi wykonano w oparciu o metodę analityczną przy rozpatrzeniu różnych materiałów jej wykonania. Do sprawdzenia wytrzymałości ramy wykorzystano metodę elementów skończonych, a obciążenie wyznaczono zgodnie z wytycznymi normy PN-EN 13749. Sam wózek jest częścią podwieszanego elektrycznego zespołu trakcyjnego zaprojektowanego w ramach pracy dyplomowej pt. „Koncepcja wagonu silnikowego kolei podwieszanej”, na wydziale Mechanicznym Politechniki Gdańskiej.
Stress Detection of Children With ASD Using Physiological Signals
- Sevgi Nur Bilgin Aktas
- Pinar Uluer
- Buket Coskun
- Elif Toprak
- Duygun Erol Barkana
- Hatice Kose
- Tatjana Zorcec
- Ben Robins
- Agnieszka Landowska
2022
This paper proposes a physiological signal-based stress detection approach for children with autism spectrum disorder (ASD) to be used in social and assistive robot inter- vention. Electrodermal activity (EDA) and blood volume pulse (BVP) signals are collected with an E4 smart wristband from children with ASD in different countries. The peak count and signal amplitude features are derived from EDA signal and used in order to detect the stress of children based on the previously provided reference baselines. Furthermore, a comparison has been made with the stress values determined using low frequency (LF) and high frequency (HF) values extracted from BVP signal.
Stress Detection of Children with Autism using Physiological Signals in Kaspar Robot-Based Intervention Studies
- Buket Coskun
- Pinar Uluer
- Elif Toprak
- Duygun Erol Barkana
- Hatice Kose
- Tatjana Zorcec
- Ben Robins
- Agnieszka Landowska
2022
This study aims to develop a stress detection system using the blood volume pulse (BVP) signals of children with Autism Spectrum Disorder (ASD) during robot-based interven- tion. This study presents the heart rate variability (HRV) analysis method to detect the stress, where HRV features are extracted from raw BVP signals recorded from an E4 wristband during interaction studies with the social robot Kaspar. Low frequency power (LF) and high frequency power (HF) features are analyzed, and the results are verified with facial emotion analysis of the children with ASD. 21 children from 3 countries participated in the study. The results showed that physiological signals combined with affective state labels may predict the stress of children, and the children were not stressed overall their interaction with the Kaspar robot. In specific cases, the children started their session as stressed but their stress declined by the end of the session. These findings are also supported by the results of the vision- based affective state analysis
Stress–strain model of lower corroded steel plates of normal strength for fitness-for-purpose analyses
- Krzysztof Wołoszyk
- Yordan Garbatov
- Paweł Kłosowski
2022 Pełny tekst CONSTRUCTION AND BUILDING MATERIALS
This study investigates the mechanical properties of specimens made of normal strength steel subjected to lower marine immersed corrosion degradation levels (below 25 %). The specimens were corroded in laboratory conditions, and only natural factors were controlled to raise the corrosion rate (reaching the level of 1 mm/year). Three different thicknesses of plates made of normal strength of shipbuilding steel are investigated (between 5 and 8 mm). The standard tensile tests are performed for estimating the stress–strain behaviour of corroded specimens. Non-corroded specimens were tested to establish the initial mechanical properties and uncertainty level as a reference. Further, the corroded specimens were tested too. Based on that, the changes in mechanical properties (i.e. yield stress, Young modulus, ultimate tensile stress and total elongation) were analysed. It was found, that for degradation level reaching 25%, approximately 10% reduction of yield stress was observed. A new parameter, defining the area reduction, was established as more closely related to the mechanical properties deterioration than the commonly used a mean degradation level. The bilinear stress–strain model of corroded steel plates was proposed for the fitness-for-purpose analyses in the structural integrity assessment.
Strong ellipticity within the Toupin–Mindlin first strain gradient elasticity theory
- Victor Eremeev
- Markus Lazar
2022 Pełny tekst MECHANICS RESEARCH COMMUNICATIONS
We discuss the strong ellipticity (SE) condition within the Toupin–Mindlin first strain gradient elasticity theory. SE condition is closely related to certain material instabilities and describes mathematical properties of corresponding boundary-value problems. For isotropic solids, SE condition transforms into two inequalities in terms of five gradient-elastic moduli.
Structural and electrochemical heterogeneities of boron-doped diamond surfaces
- Sandra Bogdanowicz
- Jacek Ryl
2022 Pełny tekst Current Opinion in Electrochemistry
This brief review is focussed on the recent progress in studies of the heterogeneous electrochemical behaviour of various boron-doped materials extending from zero-dimensional particles through polycrystalline or nanostructured three-dimensional surfaces. A boron-doped diamond reveals large heterogeneities induced by numerous factors, inter alia multi-faceted crystallinity, inhomogeneous boron concentration, sp2/sp3-carbon ratio, surface terminations and grain size distribution. We also present single nanodiamond particles and a nanostructured diamond, which are fabricated by either a top-down or a bottom-up procedure. Nanoarchitectured surfaces allow high areas and large aspect ratios to be achieved, exhibiting highly heterogeneous charge-transfer performance for catalytic, sensing and energy applications. We have anticipated multi-factor-originated heterogeneities of various boron-doped diamond surfaces displaying the essential fabrication and diagnostic methodologies and critically reviewing their benefits and drawbacks.
Structural properties of mixed conductor Ba1−xGd1−yLax+yCo2O6−δ
- Ragnar Strandbakke
- David S. Wragg
- Magnus Helgerud Sørby
- Matylda N. Guzik
- Anette E. Gunnæs
- Iga Szpunar
- Sebastian Wachowski
- María Balaguer
- Patricia A. Carvalho
- Aleksandra Mielewczyk-Gryń
- Jose M. Serra
- Truls Norby
2022 Pełny tekst DALTON TRANSACTIONS
Ba1−xGd1−yLax+yCo2O6−δ (BGLC) compositions with large compositional ranges of Ba, Gd, and La have been characterised with respect to phase compositions, structure, and thermal and chemical expansion. The results show a system with large compositional flexibility, enabling tuning of functional properties and thermal and chemical expansion. We show anisotropic chemical expansion and detailed refinements of emerging phases as La is substituted for Ba and Gd. The dominating phase is the double perovskite structure Pmmm, which is A-site ordered along the c-axes and with O vacancy ordering along the b-axis in the Ln-layer. Phases emerging when substituting La for Ba are orthorhombic Ba-deficient Pbnm and cubic LaCoO3-based R[3 with combining macron]c. When La is almost completely substituted for Gd, the material can be stabilised in Pmmm, or cubic Pm[3 with combining macron]m, depending on thermal and atmospheric history. We list thermal expansion coefficients for x = 0–0.3, y = 0.2.
Structure and Stability Characterization of Natural Lake Pigments Made from Plant Extracts and Their Potential Application in Polymer Composites for Packaging Materials
- Bolesław Szadkowski
- Małgorzata Kuśmierek
- Magdalena Śliwka-Kaszyńska
- Anna Marzec
2022 Pełny tekst Materials
Natural dyes were extracted from various plant sources and converted into lake pigments based on aluminum and tin. Three different plants (weld, Persian berries, and Brazilwood) were chosen as representative sources of natural dyes. High-performance liquid chromatography (HPLC) and triple-quadrupole mass spectrometry (QqQ MS) were used to identify dyestuffs in the raw extracts. The natural dyes and lake pigments were further characterized by optical and scanning electron microscopy (SEM), UV-Vis spectrophotometry, and thermogravimetric analysis (TGA). The stabilization of the studied plant extracts onto aluminum and tin salts led to the formation of natural lake pigments characterized by different color shades. The natural lake pigments showed improved thermal and chemical stability, which was confirmed by their higher degradation temperatures and lower solubility in chemical agents compared to natural dyes extracted from plants. This improvement can be attributed to electrostatic attraction due to the process of chelation. Ethylene- norbornene (EN) composites colored with the lake pigments exhibited uniform color and improved resistance to long-term UV exposure aging. After 300 h of UV exposure, the aging factor of the neat EN copolymer reduced to 0.3, indicating an advanced aging process of polymer compared to colored samples. Prolonged UV exposure deteriorated the mechanical properties of EN by approximately 57%, compared to about 43% with the application of BW/Al lake pigment. Natural lake pigments could be used as effective substitutes for commercial colorants in plastics for packaging applications.
Structure and the Biochemical Potential of the Bacterial Community in Wastewater Treatment Plant Effluent and in Receiving Waters: Northern Poland Case Study
- Agnieszka Kalinowska
- Mattia Pierpaoli
- Krystyna Kozioł
- Katarzyna Jankowska
- Sylwia Fudala-Kaiążek
- Anna Remiszewska-Skwarek
- Aneta Łuczkiewicz
2022
Wastewater treatment processes are monitored mainly in terms of biogenic substance removal efficiency. Little is known about the treated wastewater microbiome and its influence on the recipient. In this study, a wide range of methods (cultivation, microscopic analysis, New Generation Sequencing and Real Time PCR) were employed to determine the bacterial community composition of the treated wastewater and its receiver. Preliminary results of the study show that the wastewater impact on the marine receiver is not clearly visible on the higher taxonomic level of the microbial community (phylum) or in microscopic observations. However, it can be noted in the results of cultivation methods (eg. E. coli presence) and in the lower taxonomic levels, eg. specific groups of human-related bacteria, including pathogens, as well as microorganisms involved in nutrient cycling.
Struktury oraz mapy przepływu R1233zd w okrągłym minikanale przy średnich i wysokich wartościach ciśnienia zredukowanego [w:] Postępy w badaniach wymiany ciepła i masy
- Stanisław Głuch
- Michał Pysz
- Dariusz Mikielewicz
2022 Pełny tekst
W wiedzy dotyczącej struktur przepływu niskowrzących czynników roboczych w zakresie wysokich temperatur nasycenia (powyżej 120°C) oraz średnich i wysokich wartościach ciśnienia zredukowanego (0.5-0.9) występuje luka. W literaturze obecne są dane dotyczące podobnych wartości ciśnień zredukowanych, ale dla niższych wartości temperatury nasycenia (głównie z zakresu -20°C do 40°C). Wynika to z dotychczasowych zastosowań chłodniczych tych czynników. Stosuje się je oprócz chłodnictwa w energetyce. Przy wysokich wartościach ciśnienia zredukowanego gęstość fazy gazowej jest stosunkowo wysoka, a gęstość fazy ciekłej niska. Pomiędzy fazą ciekłą i gazową występuje niska różnica objętości właściwej. Faza ciekła ma niską wartość napięcia powierzchniowego. Faza gazowa charakteryzuje się stosunkowo wysoką lepkością, a faza ciekła ma obniżoną lepkość. Te zmiany parametrów czynników chłodniczych powoduje znaczne różnice w strukturach przepływu. Przy niskiej wartości ciśnienia zredukowanego, 0,2, zaobserwowano wystąpienie przepływu pierścieniowego już przy stopniu suchości 0,07 dla prędkości masowej G=355 [kg/(m^2*s)], natomiast dla ciśnienia zredukowanego o wartości 0,6 przepływ pierścieniowy występuje dużo później, przy stopniu suchości 0,4 dla tej samej prędkości masowej. Zaprezentowano mapy przepływu prędkości masowej w funkcji stopnia suchości dla stałych wartości ciśnienia zredukowano oraz mapy przepływu dla ciśnienia zredukowanego w funkcji stopnia suchości przy stałej prędkości masowej.
Students and Young Professionals of the IEEE IES in the Time of Information, Automation, and Energy Transformation [Students and Young Professionals News]
- Wenbin Dai
- Kim Fung Tsang
- Lucia Lo Bello
- Yousef Ibrahim
- Frivaldsky Michal
- Marek Turzyński
- Ludwig S. Sahesch-Pur
- Regina Roos
- Auday Al-Dulaimy
- Moris Behnam
- Marek Jasinski
2022 Pełny tekst IEEE Industrial Electronics Magazine
Reports on IEEE IES Society student activities in year 2021.
Study of the anticancer potential of Cd complexes of selenazoyl-hydrazones and their sulfur isosters
- Sanja B. Marković
- Natalia Maciejewska
- Mateusz Olszewski
- Aleksandar Višnjevac
- Adrián Puerta
- José M. Padrón
- Irena Novaković
- Snežana Kojić
- Henrique S. Fernandes
- Sérgio F. Sousa
- Sandra Ramotowska
- Agnieszka Chylewska
- Mariusz Makowski
- Tamara R. Todorović
- Nenad R. Filipovići
2022 EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY
The biological activity of Cd compounds has been investigated scarce since Cd has been recognized as a human carcinogen. However, the toxicity of cadmium is comparable to the toxicity of noble metals such as Pt and Pd. The paradigm of metal toxicity has been challenged suggesting that metal toxicity is not a constant property, yet it depends on many factors like the presence of appropriate ligands. Studies on anticancer activity of cadmium complexes showed that the complexation of various ligands resulted in complexes that showed better activities than approved drugs. In the present study, cadmium complexes with biologically potent thiazolyl/selenazoyl-hydrazone ligands have been prepared, and tested for their activity against different types of tumor cell models. The complexation of ligands with Cd(II) resulted in a synergistic effect. The antiproliferative activity study revealed that all complexes are more active compared to 5-fluorouracil and cisplatin. The mechanism of tumor cell growth inhibition reveal that selenium-based compounds induce cell death in T-47D (gland carcinoma) cells through apoptosis via caspase-3/7 activation. Additionally, their pro-apoptotic effect was stronger compared to etoposide and cisplatin. Nuclease activity, detected by gel electrophoresis, may be the possible mechanism of anticancer action of investigated complexes.
Study of the Effectiveness of Model Order Reduction Algorithms in the Finite Element Method Analysis of Multi-port Microwave Structures
- Grzegorz Fotyga
2022
The purpose of this paper is to investigate the effectiveness of model order reduction algorithms in finite element method analysis of multi-port microwave structures. Consideration is given to state of the art algorithms, i.e. compact reduced-basis method (CRBM), second-order Arnoldi method for passive-order reduction (SAPOR), reduced-basis methods (RBM) and subspace-splitting moment-matching MOR (SSMM-MOR)