2020 - Repozytorium publikacji - Politechnika Gdańska

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Modeling of a Quasi-Resonant DC Link Inverter Dedicated to Common-Mode Voltage and Ground Current Reduction
- Marek Turzyński
- Michal Frivaldsky
2020 Pełny tekst ENERGIES
In this paper, the modeling methodology of the AC drive system with a Parallel Quasi-Resonant DC Link Inverter (PQRDCLI) is described. A presented modeling approach is an attractive tool used for the effective evaluation of a common-mode (CM) voltage and grounds current reduction methods. Designed models of inverter, induction machine (IM), and cable are simple, thus the methods for parameter extraction are not complicated. Verification of the proposed modeling approach was realized with the use of the the Synopsys (Mountain View, CA, USA) SABER simulator, while simulation results were experimentally verified. Operation principles of the proposed PQRDCLI converter topology are also described. Based on simulation and experimental results, it was confirmed that the proposed PQRDCLI solution represents required performance within the reduction of common-mode voltage and ground current in electric drives. Moreover, comparisons from a simulation complexity point of view have been performed to the existing methods. The evaluation is being shown at the end of the paper. It is confirmed that the presented method is simple, fast, accurate, and robust as well.
Modeling of wood frame structures with different insulation materials under damaging dynamic loading
- Marcin Szczepański
- Wojciech Migda
- Robert Jankowski
2020 AIP Conference Proceedings
Wood frame buildings are very popular in regions that are exposed to different dynamic excitations, such as damaging earthquakes. Their seismic resistance is really important in order to prevent structural damages and human losses. This paper presents the results of advanced numerical investigation carried out using the FEM. Based on the models of wall panels, the numerical model of real structure of the wood frame building has been proposed for two cases of thermal insulation (using polyurethane foam and mineral wool). Then, the modal analysis for both models has been conducted so as to compare the frequencies of natural vibrations. Finally, the linear and nonlinear dynamic analyses have been carried out so as to investigate the structural behavior under damaging earthquake excitation. The results of the numerical investigation clearly confirm the beneficial effect of using polyurethane foam as thermal insulation. This can be seen both in the results of modal analysis (higher natural frequencies of building) and seismic analyses, which resulted in a significant reduction in peak values of displacements and accelerations, as compared to the case when mineral wool is applied. Moreover, the results of investigation confirm that the use of the FEM with detailed representation of material and geometric structural properties together with the Newmark algorithm can be considered as the effective approach so as to obtain the accurate response of wood frame building under dynamic loading.
Modeling process of planning finished product sales volumes at industrial enterprises in modern economic conditions
- Kateryna Udachyna
- Larysa Savchuk
- Nina Rizun
2020 Pełny tekst Przedsiębiorstwo we współczesnej gospodarce - teoria i praktyka
This article presents improving the existing system of planning finished products sales volumes. The influencing factors of the sales volumes in modern economic conditions have been determined: falling world oil prices, the reduction of pipe consumption in the domestic market, the global pandemic. The algorithm of planning finished products sales volumes has been constructed. Calculations based on the Holt forecasting method has been done, which allows to make forecast with trend. Calculations based on real data have been conducted, the model has been adapted to modern pandemic conditions, and impact factors have been identified. The plan of finished products sales volumes with factors of influence has been made. Forecast results obtained have been corrected and presented on periods and on markets. System of planning finished product sales volumes at industrial enterprises in modern economic conditions has been improved.
Modeling, simulation, and validation of a TB41 crash test of the H2/W5/B concrete vehicle restraint system
- Łukasz Pachocki
- Dawid Bruski
2020 Pełny tekst Archives of Civil and Mechanical Engineering
The paper addresses numerical simulations of a concrete vehicle restraint system. The model is described in detail. The advanced material law of the continuous surface cap model was used to analyze the damage locations in concrete barrier segments. The results were validated against the TB41 full-scale crash test. The test was conducted in compliance with European standard EN 1317, and the validation was performed in accordance with the PD CEN/TR 16303 technical report. The force and moment envelopes of the road safety barrier during a vehicle crash are provided. The detailed concrete segment model successfully reproduced the characteristic splitting failure cracks that were found near the connection of the adjacent barrier segments in the actual structure after the full-scale crash test.
Modelling of Abdominal Wall Under Uncertainty of Material Properties
- Katarzyna Szepietowska
- Izabela Lubowiecka
- Benoit Magnain
- Eric Florentin
2020 Pełny tekst
The paper concerns abdominal wall modelling. The accurate prediction and simulation of abdominal wall mechanics are important in the context of optimization of ventral hernia repair. The shell Finite Element model is considered, as the one which can be used in patient-specific approach due to relatively easy geometry generation. However, there are uncertainties in this issue, e.g. related to mechanical properties since the properties may vary naturally or as an effect of identification accuracy etc. The aim of the study is to include uncertainties in the modelling and investigate their influence on the model response. The parameters of Gasser-Ogden-Holzapfel hyperelasticmaterialmodel including fibre orientation are treated here as random variables. The uncertainties are propagated with the use of regression based polynomial chaos expansion method. Sobol’ indices are used as the measures of global sensitivity analysis and they provide information about the influence of input uncertainties on the uncertainty of the model output. Uncertainty of parameter affecting stiffness of ground substance (C10) has the highest contribution to the variation of the displacement of chosen point in the center of the abdominal wall.
Modelling of dielectric properties of BiNbO4-based microwave ceramics
- Dionizy Czekaj
- Agata Lisińska-Czekaj
- Barbara Garbarz-Glos
- Wojciech Bąk
2020 Pełny tekst ARCHIVES OF METALLURGY AND MATERIALS
In the present paper results of the studies devoted to computer simulations of dielectric response of electroceramics in a frequency domain as well as analysis of the experimental data are given. As an object of investigations BiNbO4-based microwave ceramics was taken. Simulations of the hypothetical impedance response of the ceramic system were performed under assumption of the brick-layer model. A strategy for analysis and modelling of the impedance data for microwave electroceramics was discussed. On the base of the discussed strategy modelling of the dielectric response of BiNbO4 ceramics was performed with the electric equivalent circuit method. The Voigt’s and Maxwell’s circuits were taken as electric models. Parameters of the electric components of the circuits were determined and related to parameters of the ceramic object under study. It was found that fitting quality was good and changed within the range χ2 = 6.78 × 10–4 – 6.77 × 10–5 depending on the model.
Modelling of heat and mass transfer through wooden buildings
- Rachid Méchi
- Emilia Miszewska
- Khalifa Slimi
- Robert Jankowski
2020 Proceedings of the Institution of Civil Engineers-Engineering and Computational Mechanics
The aim of this review paper is to examine the most recent available studies dealing with theoretical, numerical and experimental aspects related to modelling of heat and mass transfer through wooden buildings. The main thermophysical, mechanical and hygrometric properties of wood are firstly discussed. Then, the basic governing equations of heat and mass transfer phenomena are presented. A detailed description of the physical problem is also shown. After giving the main results from the comprehensive literature review, the authors propose future possibilities of scientific research studies for a better understanding of the complexity of thermomechanical and optimal designing aspects in wood-based construction.
Modelling of heat transfer in supercritical pressure recuperators
- Dariusz Mikielewicz
- Jarosław Mikielewicz
2020 Pełny tekst ENERGY
In the paper presented is analysis of convective flow heat transfer at supercritical pressure in channels of heat exchanger working in the thermodynamic cycle. The modelling is based on the division of the flow into three regions, namely the heavy fluid, a two phase flow consisting of the heavy and light fluids and finally the light fluid flow. Modelling is concentrated on the region of simultaneous flow of two fluids divided into the zones with the light and heavy fluids. These agents are considered with averaged thermophysical properties in each region. The surface separating the two zones with respective fluids is assumed to feature the pseudocritical temperature. The problem is solved using a previously developed theoretical model based on considerations of energy dissipation in the flow. The fundamental hypothesis in the model is the fact that heat transfer is considered as being dependent on two contributions of energy dissipation, one stemming from the shearing pseudo two-phase flow of the heavy and light fluids, whereas the second contribution comes from the energy dissipation due to exchange of mass between the heavy and light fluids. The results of calculations have been compared with some experimental data from literature showing a good consistency.
Modelling study of flow boiling heat transfer of perspective fluids for refrigeration technology
- Michał Pysz
- Dariusz Mikielewicz
2020
There is a gap of knowledge on flow boiling at high saturation temperatures and higher values of reduced pressure. Thus far, the in-house developed semi-empirical model for flow boiling and flow condensation showed a satisfactory accuracy for calculations for various refrigeration fluids for a wide scope of reduced pressures. This study presents results of calculations of heat transfer coefficient of perspective refrigeration fluids, such as R152a, R32, R245fa, propane and isobutane. Computations were carried out to validate the generalized theoretical in-house model. Study was performed for both conventional and minichannel tubes for a full range of vapour quality. The vast part of the database consists of experiments carried out for low saturation temperature, however in case of R245fa the collected data includes medium and high saturation temperatures. The theoretical results shows a good agreement with experimental data especially for low saturation temperature cases. Most unfavorable outcomes were gained for R245fa. Inconsistency of these results show that more attention should be given to the influence of higher values of reduced pressure on heat transfer predictions.
Modelowanie bezpiecznika rozłącznikowego w układach formowania impulsów wielkiej mocy
- Daniel Kowalak
- Mikołaj Nowak
- Mirosław Wołoszyn
- Kazimierz Jakubiuk
2020 Pełny tekst Przegląd Elektrotechniczny
Problem modelowania bezpieczników o dużej dynamice wyłączania prądu jest zagadnieniem szeroko opisywanym w literaturze. Układy takie mogą być wykorzystane w szczególności do formowania impulsów wysokiego napięcia o wartościach rzędu setek kV, charakteryzujących się czasem trwania rzędu ułamka μs. W niniejszej pracy przedstawiono empiryczny model bezpiecznika wielotopikowego, rozszerzony w oparciu o wyniki badań eksperymentalnych.
Modelowanie losowych imperfekcji geometrycznych przestrzennych konstrukcji metalowych
- Jarosław Górski
- Tomasz Mikulski
- Magdalena Oziębło
- Przemysław Sorn
- Karol Winkelmann
2020 Inżynieria i Budownictwo
Imperfekcje geometryczne zbiorników, silosów i powłok siatkowych mogą znaczą-co wpłynąć na ich nośność, a więc powinny być one uwzględniane w obliczeniach komputerowych i w procesie projektowania. Wykazano, że przy podstawowych obcią-żeniach, działających na tego typu konstrukcje, tj. podciśnieniu oraz naporu wiatru i śniegu (w przypadku powłok siatkowych), wykazują wyraźne różnice w porównaniu z analogicznymi wynikami dla tych konstrukcji o idealnej geometrii. Wprowadzenie me-tod probabilistycznych do projektowania oraz szacowanie niezawodności konstrukcji staje się coraz bardziej dostępne i powinno być uwzględniane w projektowaniu.
Modelowanie matematyczne transportu lodu w rejonie projektowanego Stopnia Wodnego Siarzewo
- Tomasz Kolerski
- Krzystof Wrzosek
- Przemysław Sobiesak
- Krzystof Polak
2020 Gospodarka Wodna
Przedstawiono wpływ planowanego stopnia Siarzewo na Wiśle na dynamikę lodu w obszarze powyżej i poniżej stopnia. Do tego celu zaimplementowano model matematyczny i przeprowadzono symulacje numeryczne dla różnych scenariuszy. Obliczenia służyły do wyznaczeniu trasy spływu lodu przez zbiornik i poniżej zbiornika oraz sił z jakimi lód będzie oddziaływał na brzegi i dno rzeki oraz projektowane na zbiorniku wyspy. Badaniami objęto odcinek Wisły pomiędzy istniejącym stopniem wodnym Włocławek (km 674,850) a km 715.
Models of Brushless Synchronous Generator for Studying Autonomous Electrical Power System
- Filip Kutt
2020
This is a PhD dissertation. The work presented in this monograph was carried out at the Department of Power Electronics and Electrical Machines, Faculty of Electrical and Control Engineering at the Gdansk University of Technology. Developed during the research models of brushless synchronous generator ware verified using FEM based simulations and measurements conducted on the prototype generator. The main focus of the research was toward a brushless synchronous generator in variable frequency modern more electric aircraft power systems. The generator prototype was developed and its performance was analyzed with the focus on the higher rotational velocity of the prototype components and the generated power quality. For this FEM based and circuit models of the generator ware developed and the machine performance was measured and simulated. The proposed circuit model allowed for the inclusion of nonsinusoidal spatial distribution of the magnetic flux along the air gap which in turn allowed for simulation-based power quality analysis.
Modernity and postmodernity in architectural education
- Piotr Czyż
2020 Pełny tekst World Transactions on Engineering and Technology Education
The purpose of this article is to present a philosophical education strategy for architecture and interior architecture faculties. The approach is the result of trial and error in lectures and debates with students of philosophical courses in these fields. The presented article is not a result of empirical research, but rather a report on the problems encountered and proposals for their solution. The experience gained from conducting philosophical didactics in architecture faculties allowed the author to note that the main reason for the low interest in philosophical problems is the distance between classically understood philosophy or the history of philosophy and professional issues. Bridging that gap can result in increasing the graduates’ ability to solve problems and strengthen their social competencies.
Modernized cathodic protection system for legs of the production rig – Evaluation during ten years of service
- Krzysztof Żakowski
- Piotr Igliński
- Juliusz Orlikowski
- Kazimierz Darowicki
- Kinga Domańska
2020 Pełny tekst OCEAN ENGINEERING
The modernization of cathodic protection system of the Baltic Beta platform legs is described. It was that the sacrificial anodes cone-shaped groups were to be placed on the seabed at a depth of 80 m. The measurements results of cathodic protection effectiveness during its ten-years operation are presented. The effectiveness was assessed based on the potential value along the entire length of the legs from the sea surface to the seabed. The gained experience indicates that use of sacrificial anode systems mounted on the seabed can be an effective form of cathodic protection of offshore platforms legs. It is basically the only means of anticorrosion protection in case of a platform not able to leave its location for renovation works in a shipyard.
Modification of Ground Tire Rubber—Promising Approach for Development of Green Composites
- Łukasz Zedler
- Marta Przybysz-Romatowska
- Józef Haponiuk
- Shifeng Wang
- Krzysztof Formela
2020 Pełny tekst Journal of Composites Science
Ground tire rubber (GTR) was mechano-chemically modified using a road bitumen 100/150 and two types of organic peroxides: di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB) and dicumyl peroxide (DCP). The impact of used additives on reactive sintering efficiency and physico-mechanical properties of modified GTR was investigated using oscillating disc rheometer measurements, followed by tensile tests and swelling behavior studies. It was found that the application of bitumen and both used peroxides (DCP/BIB) improves processing and reactive sintering efficiency better than untreated GTR. However, the results indicate that BIB is more prone to blooming on the surface of modified GTR, thus limiting (especially at higher content) its application as a modifier and promotor of GTR reactive sintering.
Modifications at the C(5) position of pyrimidine nucleosides
- Kozak Witold
- Sebastian Demkowicz
- Mateusz Daśko
- Janusz Rachoń
- Janusz Rak
2020 Pełny tekst RUSSIAN CHEMICAL REVIEWS
This review summarizes the state of knowledge on the chemical methods of C(5)-modifications of uridine and cytidine derivatives and may serve as a useful tool for synthetic chemists to choose an appropriate reaction protocol. The synthesis of 5-substituted uracil derivatives is gaining an increasing interest because of their possible applications in medicine and pharmacy. Modifications at the C(5) position of pyrimidine nucleosides can enhance their biostability, bioavailability or(and) biological activity. Among the C(5)-modified nucleosides, 5-halopyrimidines exhibit anticancer, antiviral, radio- and photosensitizing properties. Besides 5-halo-substituted derivatives, there are other examples of nucleosides with confirmed biological activity containing a C7C bond at the C(5) position in the pyrimidine ring. In recent decades, scientists have achieved great progress in the field of cross-coupling reactions. Among them, nickel-catalyzed processes provide a broad spectrum of synthetic methods that are based on less toxic and cheaper starting materials. This review summarizes the synthetic approaches based on the coupling or halogenation reactions, which enable 5-substituted pyrimidine nucleosides to be obtained. Moreover, the importance of the systems considered for medicine and pharmacy is briefly discussed.
Modified Manganese Phosphate Conversion Coating on Low-Carbon Steel
- Jakub Duszczyk
- Katarzyna Siuzdak
- Tomasz Klimczuk
- Judyta Strychalska-Nowak
- Adriana Zaleska-Medynska
2020 Pełny tekst Materials
Conversion coatings are one of the primary types of galvanic coatings used to protect steel structures against corrosion. They are created through chemical reactions between the metal surface and the environment of the phosphating. This paper investigates the impact that the addition of new metal cations to the phosphating reaction environment has on the quality of the final coating. So far, standard phosphate coatings have contained only one primary element, such as zinc in the case of zinc coatings, or two elements, such as manganese and iron in the case of manganese coatings. The structural properties have been determined using a scanning electron microscope (SEM), X-ray diraction (XRD), and electrochemical tests. New manganese coatings were produced through a reaction between the modified phosphating bath and the metal (Ba, Zn, Cd, Mo, Cu, Ce, Sr, and Ca). This change was noticeable in the structure of the produced manganese phosphate crystallites. A destructive eect of molybdenum and chromium was demonstrated. Microscopic analysis, XRD analysis and electrochemical tests suggest that the addition of new metal cations to the phosphating bath aects the corrosion resistance of the modified coating.
Moduł platformy SyMEC odpowiedzialny za współpracę serwera MEC z sieciami komórkowymi i bezprzewodowymi sieciami dostępowymi WLAN
- Michał Hoeft
- Krzysztof Gierłowski
- Józef Woźniak
- Wojciech Gumiński
- Krzysztof Nowicki
- Dariusz Więcek
- Igor Michalski
- Dariusz Wypiór
2020 Pełny tekst Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
Zaprezentowano moduł współpracy z sieciami dostępowymi, będący istotnym elementem serwera MEC (Multi-access Edge Computing), budowanego w ramach projektu SyMEC i umożliwiającego uruchamianie elementów aplikacyjnych na brzegu sieci. Przedstawiono różnice w wymaganiach dotyczących sposobu realizacji tego komponentu w przypadku sieci dostępowych standaryzowanych przez 3GPP oraz sieci WLAN. Zaproponowana została architektura umożliwiająca spełnienie powyższych wymagań i ujednolicenie dostępnej funkcjonalności, pomimo zróżnicowanych możliwości oferowanych przez wykorzystywane sieci dostępowe.
Molecular Dynamics simulations of thermal conductivity of penta-graphene
- Isyna Izzal Muna
- Szymon Winczewski
2020 Pełny tekst TASK Quarterly
The thermal conductivity of penta-graphene (PG), a new two dimensional carbon allotrope and its dependence on temperature, strain, and direction are studied in this paper. The thermal conductivity of PG is investigated using a non-equilibrium molecular dynamics simulation (NEMD) with the Two Region Method by applying the optimized Tersoff interatomic potential. Our study shows that the thermal conductivity of PG (determined for the [100] direction) at the room temperature of 300 K is about 18.7 W/(m K), which is much lower than the thermal conductivity of graphene. As the temperature increases, the thermal conductivity of PG is decreasing because, unlike graphene, PG has lower phonon group velocities and few collective phonon excitations. The obtained dependence of the thermal conductivity on the temperature can be described as ∼ −0.32. For the [110] direction the thermal conductivity at the room temperature of 300 K is very similar: about 17.8 W/(m K). In this case, the temperature dependence follows the ∼ −0.3 relation. Our investigations reveal that the thermal conductivity of PG is isotropic, meaning that heat transport behavior is independent of the heat flow direction. Our results indicate that the thermal conductivity of PG depends in an interesting way on the applied strain: nonmonotonic up-and-down behavior is observed. The thermal conductivity increases between strains from 0% up to 12.5%, and it decreases above a strain of 12.5%. Our investigation highlights the fascinating thermal transport properties of penta-graphene. The ultra-low thermal conductivity, the decreasing thermal conductivity with the increasing temperature, and the ultra-high mechanical strength of PG show that PG possesses a great potential in thermoelectric and nanomechanics applications. We hope that these findings, made by means of simulations, will become a bridge to inspire and encourage the experimental works, especially in the synthesis of PG.