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Gdańsk University of Technology

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Publications from the year 2019

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  • On the super domination number of lexicographic product graphs
    • Magda Dettlaff
    • Magdalena Lemańska
    • Juan A. RODRíGUEZ-VELáZQUEZ
    • Rita Zuazua
    2019 Full text DISCRETE APPLIED MATHEMATICS

    The neighbourhood of a vertexvof a graphGis the setN(v) of all verticesadjacent tovinG. ForD⊆V(G) we defineD=V(G)\D. A setD⊆V(G) is called a super dominating set if for every vertexu∈D, there existsv∈Dsuch thatN(v)∩D={u}. The super domination number ofGis theminimum cardinality among all super dominating sets inG. In this article weobtain closed formulas and tight bounds for the super dominating number oflexicographic product graphs in terms of invariants of the factor graphs involvedin the product. As a consequence of the study, we show that theproblem offinding the super domination number of a graph is NP-Hard (16) (PDF) On the super domination number of lexicographic product graphs. Available from: https://www.researchgate.net/publication/315382754_On_the_super_domination_number_of_lexicographic_product_graphs [accessed Jul 28 2020].

  • On the validation of the LS-DYNA Geo Metro numerical model
    • Dawid Bruski
    • Stanisław Burzyński
    • Jacek Chróścielewski
    • Łukasz Pachocki
    • Wojciech Witkowski
    2019 Full text MATEC Web of Conferences

    The paper presents experiences gained during work with numerical model of Geo Metro vehicle used for simulations of crash tests with road safety barriers. Attention is drawn to the subject of tire/wheel breakage during collision events. Some methods for improvement of the model are presented in the paper. Several results for the normative vehicle numerical tests are introduced. Simulations were carried out using LS-DYNA finite element code with solver version R8.1

  • On Tradeoffs Between Width- and Fill-like Graph Parameters
    • Dariusz Dereniowski
    • Adam Stański
    2019 Full text THEORY OF COMPUTING SYSTEMS

    In this work we consider two two-criteria optimization problems: given an input graph, the goal is to find its interval (or chordal) supergraph that minimizes the number of edges and its clique number simultaneously. For the interval supergraph, the problem can be restated as simultaneous minimization of the path width pw(G) and the profile p(G) of the input graph G. We prove that for an arbitrary graph G and an integer t ∈ {1, … , pw(G) + 1}, there exists an interval supergraph G′ of G such that for its clique number it holds ω(G′)≤(1+2t)(pw(G)+ 1) and the number of its edges is bounded by |E(G′)| ≤ (t + 2)p(G). In other words, the pathwidth and the profile of a graph can be simultaneously minimized within the factors of 1+2t (plus a small constant) and t + 2, respectively. Note that for a fixed t, both upper bounds provide constant factor approximations. On the negative side, we show an example that proves that, for some graphs, there is no solution in which both parameters are optimal. In case of finding a chordal supergraph, the two corresponding graph parameters that reflect its clique size and number of edges are the treewidth and fill-in. We obtain that the treewidth and the fill-in problems are also ‘orthogonal’ in the sense that for some graphs, a solution that minimizes one of those parameters cannot minimize the other. As a motivating example, we recall graph searching games which illustrates a need of simultaneous minimization of these pairs of graph parameters.

  • One Year Evaluation of Material Properties Changes of Polylactide Parts in Various Hydrolytic Degradation Conditions
    • Angela Andrzejewska
    2019 Full text Polymers

    Biodegradable biocompatible materials are widely used in medical applications. Determining the possibility of using biodegradable materials depends on determining the changes in their parameters over time due to degradation. The current scientific research on biodegradable materials has presented results based on research methods characterized by the different geometry and cross-section size of the specimen, type of degradation medium, or different pH value of the medium or maximum degradation time. This paper presents the results of a one-year study on the influence of the type of degradation medium on the changes in mechanical behavior and the uptake of the degradation medium by biodegradable specimens with large cross-sections. In addition, a prototype of a test stand was created, which allowed for the specimens to be stored vertically to ensure regular medium exposure and eliminate the interaction of the surface of the tested specimens with the sides of the container. The obtained results allowed the statistical significance of differences in the mechanical parameters determined in the uniaxial tensile test after 2, 4, 6, 12, 26, 39, and 52 weeks of degradation to be indicated depending on the type of degradation medium. It was proven that the changes in mechanical behavior depend on the percentage change in the mass of the specimens during degradation. The percentage change in mass depends on the type of degradation medium. Based on the results of this research, it was noted that in long-term degradation above 12 weeks, buffered sodium chloride solution is the optimal choice for the degradation medium. However, distilled water or physiological saline solution can be used as an alternative during the degradation period for up to 12 weeks.

  • Online brand communities’ contribution to digital business models
    • Wioleta Kucharska
    2019 Full text Journal of Research in Interactive Marketing

    Abstract Purpose – There is limited research examining social drivers and mediators of online brand community identification in the context of business models development. This study aims to identify them behind the social mechanisms and present essential factors which should be applied in business models to foster value co-creation. Design/methodology/approach – Data were collected from a convenience sample of 712 cases gathered among young European Facebook users via an electronic survey and analyzed using the structural equation modeling method. Findings – Customer–other customers’ identification is a pivotal factor in influencing brand community identification. Practical implications – If companies want to implement online brand communities into business models effectively and co-create brand value, they need deliver brand content useful for customer selfexpression and social interaction to enhance consumer-brand identification and customer–customer social bonds which enable to transform the audience into a community. Focusing on the constant reinforcement of online brand community by supporting customer–customer relationships is critical for voluntary value cocreation. Originality/value – The main contribution of this study to the literature on online brand communities is the presentation and empirical verification of pivotal social mechanisms of online brand community identification considered as a starting point to potential co-creation and capturing value based on the social presence theory.

  • Online Interactivity – Shift Towards E-textbook-based Medical Education
    • Aldona Dutkiewicz
    • Barbara Kołodziejczak
    • Piotr Leszczyński
    • Iwona Mokwa-Tarnowska
    • Paweł Topol
    • Barbara Kupczyk
    • Idzi Siatkowski
    2019 Full text Studies in Logic, Grammar and Rhetoric

    Textbooks have played the leading role in academic education for centuries and their form has evolved, adapting to the needs of students, teachers and technological possibilities. Advances in technology have caused educators to look for new sources of knowledge development, which students could use inside and outside the classroom. Today’s sophisticated learning tools range from virtual environments to interactive multimedia resources, which can be called e-textbooks. Different types of new educational materials that go beyond printed books are now used to support the academic curriculum, with the most interesting ones exemplified in this article to show their value in medical and life sciences education. Certain interesting attempts by Polish publishers at applying technology to support both self-paced and tutor-paced student learning in the medical profession and related areas are presented. The data was collected through a review of literature, discussions with e-learning specialists and medical students, as well as an analysis of examples of good practices. The article also discusses the results of a countrywide survey on the use of e-textbooks to enhance medical education. The research investigates the targeted academic staff’s attitudes towards the use of e-textbooks, the limitations of their implementation, and the character of e-resources currently used by Polish higher education medical institutions.

  • On-line Search in Two-Dimensional Environment
    • Dariusz Dereniowski
    • Dorota Osula
    2019 Full text THEORY OF COMPUTING SYSTEMS

    We consider the following on-line pursuit-evasion problem. A team of mobile agents called searchers starts at an arbitrary node of an unknown network. Their goal is to execute a search strategy that guarantees capturing a fast and invisible intruder regardless of its movements using as few searchers as possible. We require that the strategy is connected and monotone, that is, at each point of the execution the part of the graph that is guaranteed to be free of the fugitive is connected and whenever some node gains a property that it cannot be occupied by the fugitive, the strategy must operate in such a way to keep this property till its end. As a way of modeling two-dimensional shapes, we restrict our attention to networks that are embedded into partial grids: nodes are placed on the plane at integer coordinates and only nodes at distance one can be adjacent. Agents do not have any knowledge about the graph a priori, but they recognize the direction of the incident edge (up, down, left or right). We give an on-line algorithm for the searchers that allows them to compute a connected and monotone strategy that guarantees searching any unknown partial grid with the use of (√) searchers, where n is the number of nodes in the grid. As for a lower bound, there exist partial grids that require (√) searchers. Moreover, we prove that for each on-line searching algorithm there is a partial grid that forces the algorithm to use (√) searchers but (log) searchers are sufficient in the off-line scenario. This gives a lower bound on (√/log) in terms of achievable competitive ratio of any on-line algorithm.

  • Open-Phase Fault Detection Method for Sensorless Five-Phase Induction Motor Drives with an Inverter Output Filter
    • Patrick Strankowski
    • Jarosław Guziński
    • Filip Wilczyński
    • Marcin Morawiec
    • Arkadiusz Lewicki
    2019 Full text Power Electronics and Drives

    The paper presents the sensorless five-phase induction motor drive implementation with an inverter output filter with third harmonic injection. For the sensorless operation, the required observers are presented for the first and third harmonics with consideration of the inverter output filter. Moreover, the interaction of the observers and the control system is capable to handle a deactivation of one or two phases, which improves the reliability of the complete drive system. A new idea of online openphase fault detection is presented based on the frequency analysis of the estimated observer variables. The test setup, fault operation capabilities and an experimental verification of the proposed fault detection method are presented in the paper.

  • Operational harmfulness of surface contamination with abrasive after the technological lapping process = Szkodliwość eksploatacyjna skażenia powierzchni ścierniwem po procesie docierania technologicznego.
    • Adam Barylski
    2019 Full text Autobusy. Technika, Eksploatacja, Systemy Transportowe

    Przestawiono metodykę i wyniki jakościowych i ilościowych badań skażenia powierzchni mikroziarnami ściernymi oraz wpływ warunków docierania na intensywność zjawiska. W badaniach wykorzystano mikroskopie skaningową i mikroanalizę rentgenowską.

  • Opinia techniczna dotycząca oceny kierunku dzxiałań ratunkowych w Bazylice pw. Świętego Mikołaja zlokalizowanej w Gdańsku przy ulicy Świętojańskiej 72 w aspekcie zdarzenia losowego polegającego na uszkodzeniu sklepień południowej nawy bocznej
    • Tomasz Majewski
    • Maciej Niedostatkiewicz
    • Krzysztof Wilde
    • Michał Topolnicki
    • Piotr Samól
    2019

    W opracowanej Opinii technicznej przeprwadzono Analizę poprawności działań inżynierskich prowadzonych w celu ograniczenia możliwości wystąpienia katastrofy budowlanej w obszarze Bazyliki pw. Świętego Mikołaja w Gdańsku

  • Opitmalising Human Development Index with sensitivity analysis
    • Marta Kuc-Czarnecka
    2019

    Research background: Composite indicators are commonly used not only to measure economic development, the standard of livin g, competitiveness, fairness, effectiveness but are also willingly implemented in to many different fields. How- ever, it seems that in most cases the variable weig hting procedure is avoided or erroneous since in most cases so-called “wights by belief” are applied. As re- searches show, it can be frequently observed that w eights do not equal importance in composite indicators. As a result, biased rankin gs or grouping of objects are obtained. Purpose of the article: The primary purpose of this article to optimise and im- prove the Human Development Index which is the most commonly used composite indicator to rank countries in terms of their socio -economic development. Methods: In order to achieve the purpose mentioned above, th e sensitivity analysis tools (mainly the firsts order sensitivity index) w ere used to determine the appro- priate weights in the Human Development Index. Base d on the adjusted weights, a new ranking of countries was established and compil ed with the initial ranking. Findings & Value added: It has been shown that HDI is built incorrectly by put- ting equal weights for all four components. The wei ghts proposed by the sensitivity analysis better reflect the actual contribution of individual factors to HDI variabil- ity. Improved Human Development Index constructed b ased on proposed weights allow for better differentiation of countries due t o socio-economic development

  • Opowieść o "Żelaznej France", czyli jak Gdynią zarzadzano
    • Marta Szeluga-Romańska
    2019

    Artykuł przestawia postać byłej prezydent Gdyni - Franciszki Cegielskiej, ze szczególnym uwzględnieniem jej charakterystycznego sposobu zarządzania

  • Opracowanie dogodnej metody tworzenia wiązań S-C o hybrydyzacji atomu węgla sp oraz sp2
    • Justyna Doroszuk
    2019 Full text

    Badania przeprowadzone w Katedrze Chemii Organicznej Wydziału Chemicznego Politechniki Gdańskiej na przestrzeni ostatnich kilku lat, pokazały wszechstronność pochodnych kwasu neopentylidenofosforoditiowego. Dotychczasowe wyniki badań doprowadziły mnie do opracowania nowych strategii syntetycznych, umożliwiających otrzymywanie związków zawierających wiązanie C-S o hybrydyzacji atomu węgla sp oraz sp2. Analizując wyniki badań opracowałam trzy metody syntezy sulfidów S-alkinylowych. Były to reakcje acetylenków miedzi(I) z symetrycznym disulfidem kwasu neopentylidenofosforoditiowego, reakcje acetylenków litu z niesymetrycznymi pochodnymi kwasu fosforoditiowego oraz reakcje acetylenków litu z tiosulfonianami. Ponadto, ze względu na rosnące zainteresowanie związkami zawierającymi ugrupowanie -S-CH=CH2- opracowałam diastereoselektywną redukcję otrzymanych sulfidów S-alkinylowych do (Z)-sulfidów winylowych. Ponadto, opracowałam oraz zoptymalizowałam warunki reakcji sulfenylowania indoli w pozycję C2. Opracowane metody syntezy wiązania S-C o hybrydyzacji atomu węgla sp oraz sp2 charakteryzują się wysokimi wydajnościami otrzymanych produktów, ponadto łagodne warunki reakcji tolerują zastosowanie szerokiej gamy grup funkcyjnych.

  • Opracowanie ekspertyzy dotyczącej przyczyn pękania łopatek wirnika SP turbiny PG1 typu 13UP55
    • Wojciech Kiełczyński
    • Jerzy Łabanowski
    • Maria Głowacka
    • Grzegorz Gajowiec
    • Lech Nadolny
    2019

    Zakres badań i analiz dotyczył ustalenia przyczyn pękania elementów łopatek wirnika SPA5 turbiny TG1 typu 13UP55 obejmował: 1. wykonanie badań składu chemicznego stali, z której wykonano łopatki dostarczone przez Zleceniodawcę dwoma metodami, 2. badania mikroobszarów zniszczenia łopatek na mikroskopie elektronowym skaningowym z mikroanalizatorem EDS, 3. badania metalograficzne makroskopowe i mikroskopowe fragmentów łopatek w obszarze zniszczenia i pomiary rozkładu twardości łopatek w tych obszarach. Zawartość pierwiastków w stali określono niszczącą metodą instrumentalną z zastosowaniem zautomatyzowanego analizatora Leco w odniesieniu do zawartości węgla i siarki oraz metodą spektrometryczną dla określenia pozostałych składników stali. W metodzie z zastosowaniem analizatora Leco próbki stali są spalane w strumieniu czystego tlenu, a produkty spalania, w postaci CO2 i SO2 następnie podlegają analizie w komorze promieniowania podczerwonego. 1. Przyczyną zniszczenia badanych łopatek było wystąpienie bardzo twardych i kruchych struktur hartowania w obszarze nita łopatki. Martenzyt hartowania powstał podczas procesu napawania łopatki stopem niklu, w celu odbudowy jej geometrii w miejscu połączenia z bandażem. Przyczyny powstania takiej struktury w tym obszarze były dwie. Pierwsza, to decyzja o naprawie uszkodzeń za pomocą napawania, bez skutecznej kontroli spawalności materiału rodzimego, druga - stworzenie warunków cieplnych przed, w trakcie i po spawaniu nieadekwatnych dla składu chemicznego materiału łopatek z punktu widzenia warunków cieplnych spawania. Zastosowana w łopatkach stal gat. 2H13, jest bowiem samohartowna i usunięcie skutków przemiany martenzytycznej, objawiającej się wysoką twardością i towarzyszących procesowi spawania wysokiego poziomu naprężeń residualnych (pospawalniczych), wymaga wysokiego odpuszczania.

  • Optical activity and electro-optic effect of l-arginine doped KDP single crystals
    • Mykola Shopa
    • Yaroslav Shopa
    • E. Kostenyukova
    • I. Pritula
    • O. Bezkrovnaya
    2019 Full text OPTICS AND LASER TECHNOLOGY

    We have used the modified polarimetric methods to study optical activity (OA) in the potassium dihydrogenphosphate (KDP) crystals doped with 0.7, 1.4 and 3.8 wt% L-arginine (L-arg) amino acid. Crystals were grown by the temperature reduction method. Small changes of the absolute eigen waves ellipticity and OA values in doped crystals were noted. We have experimentally determined the signs of OA in the [1 00] and [01 0] directions in KDP type crystals. The electro-optical parameters (half-wave voltage and electro-optical coefficients r63) in L-arg doped crystals for fixed wavelengths of 633, 532 and 405 nm remain unchanged in comparison with the pure KDP.

  • Optical and photocatalytic properties of rare earth metal-modified ZnO quantum dots
    • Jakub Sowik
    • Magdalena Miodyńska
    • Beata Bajorowicz
    • Alicja Mikolajczyk
    • Wojciech Lisowski
    • Tomasz Klimczuk
    • Daniel Kaczor
    • Adriana Zaleska-Medynska
    • Anna Malankowska
    2019 APPLIED SURFACE SCIENCE

    A series of novel ZnO quantum dots modified with rare earth metals was successfully prepared by a simple sol-gel approach. The effects of types (Eu, Er, Tb, Yb, Ho, La) and amounts (from 0.09 to 0.45 mmol) of lanthanides on the optical properties, structural characterization and photocatalytic activity of ZnO/RE QDs were systematically investigated. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) with energy dispersive X-ray analysis (EDX) and UV–Vis diffuse reflectance spectroscopy were used to characterize surface properties, while photoluminescence (PL) emission spectroscopy and UV–Vis-driven degradation of phenol in aqueous phase were applied to understand optical and photocatalytic properties. The experiments demonstrated that generally modification of ZnO QDs by lanthanides resulted in increase of photoactivity while photoluminesce decrease at the same moment. The highest photocatalytic activity among all obtained nanomaterials and the lowest photoluminescence quantum yield among ZnO/Er photocatalysts were observed for ZnO QDs modified with 0.09 mmol of erbium. Increased photocatalytic activity has been shown in successive samples: ZnO/0.09_Er > ZnO/0.18_Eu > ZnO/0.09_La > ZnO/0.27_Er > ZnO/0.18_Tb > pristine ZnO QDs. The experimental results were supported by calculations based on density functional theory (DFT) which revealed atomic and electronic structure of Er/La modified ZnO QDs.

  • Optical investigations of electrochemical processes using a long-period fiber grating functionalized by indium tin oxide
    • Marta Janczuk-Richter
    • Monika Piestrzyńska
    • Dariusz Burnat
    • Petr Sezemsky
    • Vitezslav Stranak
    • Wojtek J. Bock
    • Robert Bogdanowicz
    • Joanna Niedziółka-Jönsson
    • Mateusz Śmietana
    2019 SENSORS AND ACTUATORS B-CHEMICAL

    he growing needs for fast and reliable sensing devices stimulate development of new technological solutions. In this work a new multi-domain sensing method is demonstrated where optical sensing device has been applied to enhance amount of data received during electrochemical analysis. Thin, optically transparent, high-refractive-index, and electrically conductive indium tin oxide (ITO) film was deposited using magnetron sputtering on the surface of the long-period gratings (LPG) induced in optical fiber. ITO serves as working electrode in electrochemical setup and as a coating that enhances sensitivity of a LPG to changes of external refractive index. All the measurements were conducted in a combined optical and electrochemical setup. Obtained results show capability of this approach for optical monitoring of both electrochemical processes and changes in optical properties at the ITO surface. The optical response of the sensor was strongly dependent on the voltage applied to the ITO-LPG working electrode and on composition of the electrolyte. Changes observed in optical spectra may be attributed to the alterations in optical properties of both ITO layer (refractive index changes) and electrolyte in the vicinity of electrode (double layer formation). The developed structures can be further used as a fiber-based sensors and biosensors with integrated opto-electrochemical readout.

  • Optical Magnetometry Based on Nanodiamonds with Nitrogen-Vacancy Color Centers
    • Adam M. Wojciechowski
    • Paulina Nakonieczna
    • Mariusz Mrózek
    • Krystian Sycz
    • Andrzej Kruk
    • Mateusz Ficek
    • Maciej Jerzy Głowacki
    • Robert Bogdanowicz
    • Wojciech Gawlik
    2019 Full text Materials

    Nitrogen-vacancy color centers in diamond are a very promising medium for many sensing applications such as magnetometry and thermometry. In this work, we study nanodiamonds deposited from a suspension onto glass substrates. Fluorescence and optically detected magnetic resonance spectra recorded with the dried-out nanodiamond ensembles are presented and a suitable scheme for tracking the magnetic-field value using a continuous poly-crystalline spectrum is introduced. Lastly, we demonstrate a remote-sensing capability of the high-numerical-aperture imaging fiber bundle with nanodiamonds deposited on its end facet.

  • Optical properties of daylight curable resin doped with nanodiamond powder
    • Krzysztof Królewski
    • Aleksandra Wieloszyńska
    • Aleksandra MARIA Kamińska
    • Katarzyna Kardacz
    2019 Full text Photonics Letters of Poland

    In this paper a new material for 3D printing was elaborated on. Since diamond has very good optical properties, an idea occurred to us to apply it in 3D printing process. A mixture of nanodiamond powder and a standard 3D printing resin was created and several printouts have been completed. They have been tested for their abilities to transmit and absorb light in a wide spectrum of wavelengths. It turned out that the nanopowder doped resin in comparison to standard one has worst optical properties. However, it shows that mixture of resin and nanopowder can control optical properties of printouts.

  • Optimal ECG lead for deriving respiratory signal
    • Piotr Przystup
    • Artur Poliński
    • Adam Bujnowski
    • Tomasz Kocejko
    • Jerzy Wtorek
    2019

    EDR is an interesting measuring technique that allows an indirect assessment of respiratory activity. This is an alternative solution to direct methods that are based on the measurement of air flow, which require a specialized sensor or even a system. However, due to inter-personal anatomical differences, the optimal ECG lead (placement of the electrodes) ensuring the best EDR signal quality is not fixed. An influence of ECG lead geometrical relation to the heart axis on the EDR signal quality has been examined in the paper. It was found that optimal electrodes position strongly differs between individuals. For each person there were at least few leads with high correlation with reference signal (over 0.8). They allowed for respiration frequency estimation with almost 100% accuracy