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Gdańsk University of Technology

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Publications from the year 2020

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  • Experimental and computational study on mechanical behaviour of carpentry corner log joints
    • Paweł Kłosowski
    • Anna Pestka
    • Marcin Krajewski
    • Izabela Lubowiecka
    2020 Full text ENGINEERING STRUCTURES

    This work concerns experimental and numerical research on carpentry joints used in historic wooden buildings in southeastern Poland and western Ukraine. These structures are mainly sacred buildings, and the types of corner log joints characteristic of this region are primarily saddle-notch and dovetail joints; thus, these two types of joints were analysed in this study. The modelling of historic timber structures is a complex issue, so the following steps are necessary to obtain accurate solutions: verification, validation and uncertainty quantification. The first and third steps were performed in a previous study, so the current research aimed to validate the numerical models and perform simulations of carpentry joints. Herein, the authors created finite element models of two types of joints and subsequently analysed the mechanical behaviour of these joints. Due to issues concerning model validation, the authors designed a testing stand for corner joints, which formed a part of a biaxial testing machine. The joints were subjected to horizontal loads (deformations), which may cause damage to the connection. Thus, special parts were designed for the stand, which made it possible to fix the joint and prevented eccentric forces that could possibly damage the machine during testing. The authors presented the differences and similarities in the behaviour of both types of joints, emphasizing the corresponding advantages and disadvantages. In addition, the authors determined which type of joint was the most susceptible to damage and what elements failed first. This paper also showed the complexity of modelling timber structures and the accuracy of the proposed numerical models for both types of joints through comparisons of the numerical and experimental results. This work primary addressed the problems in accurately reflecting material, load and boundary conditions in numerical modelling of tested carpentry corner log joints.

  • Experimental and DFT insights into an eco-friendly photocatalytic system toward environmental remediation and hydrogen generation based on AgInS2 quantum dots embedded on Bi2WO6
    • Patrycja Parnicka
    • Alicja Mikolajczyk
    • Henry P. Pinto
    • Wojciech Lisowski
    • Tomasz Klimczuk
    • Grzegorz Trykowski
    • Beata Bajorowicz
    • Adriana Zaleska-Medynska
    2020 APPLIED SURFACE SCIENCE

    Bismuth tungstate (Bi2WO6) can work as a photocatalyst but suffers from rapid recombination of photogenerated charge carriers. Herein, density functional theory (DFT) simulations revealed that the formation of a thermodynamically stable AgInS2(112)/Bi2WO6(010) heterojunction could promote charge separation and enhance the photoactivity of Bi2WO6. To confirm these theoretical predictions, a new type of photocatalysts in the form of Bi2WO6 flower-like microspheres decorated with different amounts of AgInS2 quantum dots (QDs) was obtained using a three-step procedure. The optimized system, obtained by embedding 1 wt% AgInS2 QDs on a Bi2WO6 matrix, possessed an enhanced photocatalytic activity for both phenol degradation and water splitting under visible light irradiation (λ > 420 nm), as well as good reusability and stability during prolonged storage. Finally, DFT calculations of the adsorption energies of reagents (O2, H2O, and H2 molecules) on Bi2WO6 and AgInS2/Bi2WO6 surfaces showed that the surface of the AgInS2(112)/Bi2WO6(010) interface was more active, allowing this system to strongly interact with surrounding species such as H2, O2, and H2O and thereby inducing photocatalytic oxidation of OH– to •OH, reduction of O2 to O2 •– or reduction of H+ to H2.

  • Experimental and Numerical Investigation of Mechanical Properties of Lightweight Concretes (LWCs) with Various Aggregates
    • Marzena Kurpińska
    • Tomasz Ferenc
    2020 Full text Materials

    High requirements for the properties of construction materials and activities directed at environment protection are reasons to look for new solutions in concrete technology. This research was directed at solutions affecting the reduction of energy consumption and CO2 emissions. The use of lightweight concretes (LWCs) allows one to meet both conditions at the same time. The purpose of the research presented in this paper was to investigate the abilities of using lightweight aggregates (LWAs) of the following types: 2 and 4 mm granulated expanded glass aggregate (GEGA) as ingredients with excellent insulating properties and 8 mm granulated fly ash aggregate (GAA) as an ingredient with a relatively high resistance to crushing. The influence of the percentage participation of each aggregate in all LWCs was variable and amounted to 0%, 25%, 50%, 75%, and 100%. A series of 15 LWC mixes were prepared for various LWA participations and for a constant water–cement ratio (w/c = 0.5). Concrete tests were carried out for the following criteria: density, porosity, compressive strength, and the modulus of elasticity. In order to fully analyze fracture processes in LWCs with the participation of GEGA and GAA and to assess the correctness of the results obtained during the experiments, numerical models that corresponded to both geometrical and load diagrams of elements under research were created. The numerical analyses of the LWCs were conducted by means of the conventional finite element method (FEM).

  • Experimental and numerical investigations of ultimate strength of imperfect stiffened plates of different slenderness
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    • Jakub Kowalski
    • Leszek Samson
    2020 Full text Polish Maritime Research

    The objective of this study is to analyse the behaviour of compressed stiffened plates of different slenderness using experimental and numerical methods. The presented results are part of a long-term project to investigate the ultimate strength of geometrically imperfect structures subjected to different degradation phenomena, including corrosion degradation and locked cracks. Several specimens were subjected to a uniaxial compressive force, and the most important quantities related to the structural behaviour were captured and analysed. A finite element model, accounting for material and geometrical nonlinearities and initial geometrical imperfections, was developed using the commercial software ANSYS. The residual welding-induced stresses were measured in the middle cross-section for two specimens. The initial imperfection was identified by employing a close-range photogrammetry approach. It was concluded that the numerical analyses, based on the finite element model, predict the ultimate strength of stiffened plates accurately, although some deviations were also observed. The detailed analysis with the indication of possible uncertainty is presented, and several conclusions are derived.

  • Experimental and Numerical Study on Dynamics of Two Footbridges with Different Shapes of Girders
    • Anna Banaś
    • Robert Jankowski
    2020 Full text Applied Sciences-Basel

    The paper presents the experimental and numerical results of the dynamic system identification and verification of the behavior of two footbridges in Poland. The experimental part of the study involved vibration testing under different scenarios of human-induced load, impulse load, and excitations induced by vibration exciter. Based on the results obtained, the identification of dynamic parameters of the footbridges was performed using the peak-picking method. With the impulse load applied to both structures, determination of their natural vibration frequencies was possible. Then, based on the design drawings, detailed finite element method (FEM) models were developed, and the numerical analyses were carried out. The comparison between experimental and numerical results obtained from the modal analysis showed a good agreement. The results also indicated that both structures under investigation have the first natural bending frequency of the deck in the range of human-induced excitation. Therefore, the risk of excessive structural vibrations caused by pedestrian loading was then analysed for both structures. The vibration comfort criteria for both footbridges were checked according to Sétra guidelines. In the case of the first footbridge, the results showed that the comfort criteria are fulfilled, regardless of the type of load. For the second footbridge, it was emphasized that the structure meets the assumptions of the guidelines for vibration severability in normal use; nevertheless, it is susceptible to excitations induced by synchronized users, even in the case of a small group of pedestrians.

  • Experimental and predicted physicochemical properties of monopropanolamine-based deep eutectic solvents
    • Bartosz Nowosielski
    • Marzena Jamrógiewicz
    • Justyna Łuczak
    • Maciej Śmiechowski
    • Dorota Warmińska
    2020 Full text JOURNAL OF MOLECULAR LIQUIDS

    In this work, the novel deep eutectic solvents (DESs) based on 3-amino-1-propanol (AP) as hydrogen bond donor (HBD) and tetrabutylammonium bromide (TBAB) or tetrabutylammonium chloride (TBAC) or tetraethylammonium chloride (TEAC) as hydrogen bond acceptors (HBAs) were synthesized with different molar ratios of 1:4, 1:6 and 1:8 salt to AP. Fourier Transform Infrared Spectroscopy measurements were performed to provide an evidence of any chemical structure changes. Physical properties of the prepared DESs including densities, viscosities, refractive indices and sound velocities were measured within the temperature range of 293.15 – 333.15 K at the pressure of 0.1 MPa. They were analysed in terms of estimating the effect of HBA to HBD molar ratio, anion and length of alkyl chain in a salt, and their temperature dependences were fitted by empirical equations. Thermal expansion coefficients and activation energies for viscous flow were obtained accordingly. Moreover, experimental values of density and refractive index were compared with predicted ones. For prediction of density, Rackett equation modified by Spencer and Danner and the mass connectivity index-based method were used, while refractive index was estimated by the atomic contribution method.

  • Experimental certification of an informationally complete quantum measurement in a device-independent protocol
    • Massimiliano Smania
    • Piotr Mironowicz
    • Mohamed Navareg
    • Marcin Pawłowski
    • Adan Cabello
    • Mohamed Bourennane
    2020 Full text Optica

    Minimal informationally complete positive operator-valued measures (MIC-POVMs) are special kinds of measurement in quantum theory in which the statistics of their d2-outcomes are enough to reconstruct any d-dimensional quantum state. For this reason, MIC-POVMs are referred to as standard measurements for quantum information.Here, we report an experiment with entangled photon pairs that certifies, for what we believe is the first time, a MIC-POVM for qubits following a device-independent protocol (i.e., modeling the state preparation and the measurement devices as black boxes, and using only the statistics of the inputs and outputs). Our certification is achieved under the assumption of freedom of choice, no communication, and fair sampling.

  • Experimental investigation of joint with positive eccentricity in CFS truss
    • Małgorzata Gordziej-Zagórowska
    • Elżbieta Urbańska-Galewska
    • Patryk Deniziak
    2020 Full text THIN-WALLED STRUCTURES

    Due to technological restrictions, in the case of trusses made of CFS open cross-sections, positive eccentricities in the truss joints have become very frequent. Therefore studies concerning the load-bearing capacity of truss joints with positive eccentricity were undertaken. It was assumed that the resistance of cold-formed steel (CFS) open cross-section truss joints located on compression chords and with positive eccentricity is greater than that which results from hitherto known methods of steel structure dimensioning. In order to confirm the hypothesis, experimental studies were conducted. A series of 5 full-scale research models was subjected to destructive tests to determine the deformation forms and strains of the hat-section walls in the area of the eccentric joint. Forms of truss chord stability loss under compression and bending were identified. The course of research and analysis of results were described in the article. Than comparative analysis of the outcomes of the experimental tests and the results of analytical calculations carried out according to Eurocode standards was done, and the obtained results confirmed the usefulness of the undertaken research. The obtained results did not allow for explicit confirmation of the research hypothesis at this stage, but constituted the basis for validation of the numerical model which has been elaborated. Currently, the authors carry out a variety of numerical analysis.

  • Experimental Investigations on the Influence of Coil Arrangement on Melting/Solidification Processes
    • Rafał Andrzejczyk
    • Przemysław Kozak
    • Tomasz Muszyński
    2020 Full text ENERGIES

    The latent heat thermal energy storage units are very popular because of their high energy density and almost close to constant temperature during the charging/discharging. In the present study has been proposed new shell-and-coil geometry with a shifted coil position to enhance the performance of phase change thermal magazine. The experimental investigations have been performed both for the melting and solidification process of coconut oil for constant wall temperature conditions. The experiments have been carried out for cylindrical as well as coil shape geometry of the TES unit. In the case of annular TES, the copper tube with outer diameter d = 10 mm and total length equal to 165 mm were used (4). In the case of shell-and-coil TES the coil has been also made of a copper tube but with an outer diameter d = 6 mm. The total length of the tube was 460 mm. However, the length of the tube element that has been used in the process of bending the coil had a total length equal to 360 mm. The rest of the tube was straight. The coil pitch was 15 mm and the outer coil diameter was 26 mm. The experiments have been conducted for the coil position at the top and the bottom of the tank. The results showed the influence of heat transfer geometry for phase change efficiency. The article presents the thermal characteristic of melting and solidification phenomena as well as their visual analysis. A significant impact of heat transfer geometry at the shape of the melting and solidification profile. The optimal performance has been achieved for shell-and-coil TES with a coil arranged at the top of the tank.

  • Experimental Research on Insufficient Water Lubrication of Marine Stern Tube Journal Bearing with Elastic Polymer Bush
    • Agnieszka Barszczewska
    2020 Full text Polish Maritime Research

    Water-lubricated bearings with polymer bushes are steadily gaining popularity due to their advantages, including environmental friendliness, relatively simple construction and long-term operation. Nevertheless, in practice instances of damage to such bearings occur due to insufficient or absent flow of the lubricating agent. In this study, experimental tests established that elastic polymer bush bearing is capable of operating without excessive wear for a period of at least 60 minutes under conditions of marginal water flow and typical loads for stern tube journal bearings of small ships.

  • Experimental Studies of Concrete-Filled Composite Tubes under Axial Short- and Long-Term Loads
    • Marcin Abramski
    • Piotr Korzeniowski
    • Krzysztof Klempka
    2020 Full text Materials

    The paper presents experimental studies on axially compressed columns made of concrete-filled glass fiber reinforced polymer (GFRP) tubes. The infill concrete was C30/37 according to Eurocode 2. The investigated composite pipes were characterized by different angles of fiber winding in relation to the longitudinal axis of the element: 20, 55 and 85 degrees. Columns of two lengths, 0.4 m and 2.0 m, were studied. The internal diameter and wall thickness of all the pipes were identical and amounted to 200 mm and 6 mm, respectively. The mean values of two mechanical properties, elasticity modulus and compression strength, were determined. These properties were determined for longitudinal compression and for circumferential tension. The graphs of longitudinal and peripheral deformations of polymer shells as a function of load level are presented both for empty tubes and for concrete-filled ones. The results of long-term investigations of three identically made 0.4 m high concrete-filled GFRP tubes are also presented.

  • Experimental Study on the Effectiveness of Polyurethane Flexible Adhesive in Reduction of Structural Vibrations
    • Natalia Lasowicz
    • Arkadiusz Kwiecień
    • Robert Jankowski
    2020 Full text Polymers

    The aim of the present study is to consider the idea of using polyurethane flexible adhesive in to reduce the vibrations in structures exposed to dynamic loads and evaluate their damping properties in relation to large deformations. Firstly, two aluminium cantilever beams, simulating structural elements (without and with polyurethane layer in the form of tape), were analysed, in order to check the damping of the unconstrained polymer layer. In the second stage of the study, a composite beam consisting of two aluminium flat beams bonded with polymer adhesive was considered, so as to check the damping of the constrained polymer layer. Dynamic parameters, such as modes of free vibrations, corresponding natural frequencies and damping ratios, were determined and compared. The third stage of the investigation was aimed at solving the problem of the additional mass of the applied polymer layer, which influences the frequencies and damping of the tested structure. A special separating procedure is proposed that makes it possible to calculate the corrected real values of the polymer layer’s damping. The results of the study clearly show that the response of the composite aluminium beam with and without polymer adhesive layer is mainly influenced by the layers’ thickness and the large strain deformation, in terms of its damping characteristics. The use of polymer adhesive layers in constrained and unconstrained conditions leads to a significant reduction in the vibrations of tested beams, while preserving their stiness at nearly the same level. The applied analysis procedure made it possible for us to separate the damping properties of the analysed polymer layers and evaluate them independently with respect to the influence of integrated structural elements on damping.

  • Experimental study on the selected aspects of bow thruster generated flow field at ship zero-speed conditions
    • Teresa Abramowicz-Gerigk
    • Mirosław Gerigk
    2020 OCEAN ENGINEERING

    The paper presents the results of experimental study on the interaction between the bow thrusters understood as the flow field changes generated by bow tunnel thruster in deep water conditions operated as a single and twin units. The research was limited to zero-speed case for the ship dead in the water. The influence of the hull form and jet spread between the neighbouring thrusters for several combinations of the applied bow thruster propeller revolutions has been discussed. The results of the flow field measurements - velocity field, volume of fluid rate, mean velocity and thrust have been compared with the measurements of hydrodynamic forces generated by the bow thrusters on the hull. Both experiments were conducted at zero-speed using the same large physical man-manned model of a car-passenger ferry in 1:16 scale.

  • Experimental test of nonclassicality with arbitrarily low detection efficiency
    • Alley Hameedi
    • Breno Marque
    • Piotr Mironowicz
    • Debashis Saha
    • Marcin Pawłowski
    • Mohamed Bourennane
    2020 Full text PHYSICAL REVIEW A

    We theoretically introduce and experimentally demonstrate the realization of a nonclassicality test that allows for arbitrarily low detection efficiency without invoking an extra assumption of independence of the devices. Our test and its implementation is set in a prepare-and-measure scenario with an upper limit on the classical communication capacity of the channel through which the systems are communicated. The essence for our test is the use of two preparation and two measurement devices, which are randomly paired in each round. Our work opens the possibility for experimental realizations of nonclassicality tests with off-the-shelf technology.

  • Explainable AI for Inspecting Adversarial Attacks on Deep Neural Networks
    • Zuzanna Klawikowska
    • Agnieszka Mikołajczyk
    • Michał Grochowski
    2020 Full text

    Deep Neural Networks (DNN) are state of the art algorithms for image classification. Although significant achievements and perspectives, deep neural networks and accompanying learning algorithms have some important challenges to tackle. However, it appears that it is relatively easy to attack and fool with well-designed input samples called adversarial examples. Adversarial perturba-tions are unnoticeable for humans. Such attacks are a severe threat to the devel-opment of these systems in critical applications, such as medical or military sys-tems. Hence, it is necessary to develop methods of counteracting these attacks. These methods are called defense strategies and aim at increasing the neural mod-el's robustness against adversarial attacks. In this paper, we reviewed the recent findings in adversarial attacks and defense strategies. We also analyzed the ef-fects of attacks and defense strategies applied, using the local and global analyz-ing methods from the family of explainable artificial intelligence.

  • Exploratory analysis and ranking of analytical procedures for short-chain chlorinated paraffins determination in environmental solid samples
    • Mariusz Marć
    • Marta Bystrzanowska
    • Marek Tobiszewski
    2020 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    Short-chain chlorinated paraffins are ones of the most recent chemical compounds that have been classified as persistent organic pollutants. They have various applications and are emitted to the environment. Despite the fact, that the content levels of these compounds in the environmental compartments should be monitored, there is still a lack of well-defined and validated analytical procedures, proposed or suggested by the national or international environmental protection agencies. Finding an appropriate analytical procedure (sensitive and green at the same time) from many available ones is very often a difficult task. Therefore it can be supported with multicriteria decision analysis. The dataset consisting of 22 procedures was described by 7 criteria, mainly referring to procedures greenness. The data treatment with cluster analysis and principal component analysis revealed the internal structure of the dataset. Moreover, both statistical tools allowed for reduction of dataset criteria to three. This was used for applying ternary plot to show the multicriteria decision analysis results within all possible weights. With the aid of chemometric and multicriteria decision analysis tools it was easy to assess the set of analytical procedure. Depending on the applied weights to assessment criteria different analytical procedures are the most appropriate (winners).

  • Exploring application relationships within enterprise system by matching messages in enterprise log
    • Krzysztof Goczyła
    • Łukasz Korzeniowski
    2020

    With data becoming their key asset, large enterprises require data governance processes to maintain its quality. Because a large portion of business value in enterprise systems is usually delivered by legacy applications without proper documentation, there is a need for a better understanding of these applications and the data produced by them. In this paper, we present an approach to collecting insights into the data managed by enterprise systems by exploring enterprise logs in the search of messages being exchanged between applications. Our method identifies data assets from the extracted messages and finds relationships between them. Based on our professional practice, we verify the method in a generic environment that simulates an enterprise system consisting of applications that exchange XML messages.

  • Exploring Impact of Requirements Engineering on Other IT Project Areas – Case Study
    • Aleksander Jarzębowicz
    • Katarzyna Poniatowska
    2020 Full text Computer Science

    Requirements Engineering (RE) is recognized as one of the most important (yet difficult) areas of software engineering that has a significant impact on other areas of IT projects and their final outcomes. Empirical studies investigating this impact are hard to conduct, mainly due to the great effort required. It is thus difficult for both researchers and industry practitioners to make evidence-based evaluations about how decisions about RE practices translate into requirement quality and influence other project areas. We propose an idea of a lightweight approach utilizing widely-used tools to enable such an evaluation without extensive effort. This is illustrated with a pilot study where the data from six industrial projects from a single organization were analyzed and three metrics regarding the requirement quality, rework effort, and testing were used to demonstrate the impact of different RE techniques. We also discuss the factors that are important for enabling the broader adoption of the proposed approach.

  • Exploring the Role of Social Media Use Motives, Psychological Well-Being, Self-Esteem, and Affect in Problematic Social Media Use
    • Bruno Schivinski
    • Magdalena Brzozowska-Woś
    • Ellena Stansbury
    • Jason Satel
    • Christian Montag
    • Halley M. Pontes
    2020 Full text Frontiers in Psychology

    Given recent advances in technology, connectivity, and the popularity of social media platforms, recent literature has devoted great attention to problematic Facebook use. However, exploring the potential predictors of problematic social media use beyond Facebook use has become paramount given the increasing popularity of multiple alternative platforms. In this study, a sample of 584 social media users (Mage = 32.28 years; 67.81% female) was recruited to complete an online survey assessing sociodemographic characteristics, patterns, and preferences of social media use, problematic social media use (PSMU), social media use motives, psychological well-being, self-esteem, and positive and negative affect. Results indicated that 6.68% (n = 39) of all respondents could be potentially classed as problematic users. Moreover, further analysis indicated that intrapersonal motive (β = 0.38), negative affect (β = 0.22), daily social media use (β = 0.18), surveillance motive (β = 0.12), and positive affect (β = −0.09) each predicted PSMU. These variables accounted for about 37% of the total variance in PSMU, with intrapersonal motive driving the greatest predictive contribution, over and above the effects of patterns of social media use and sociodemographic variables. These findings contribute to the increasing literature on PSMU. The results of this study are discussed in light of the existing literature on PSMU.

  • Exploring thiophene-2-acetate and thiophene-3-acetate binding modes towards the molecular and supramolecular structures and photoluminescence properties of Pb(ii) polymers
    • Mateusz Kowalik
    • Joanna Masternak
    • Katarzyna Kazimierczuk
    • Bogumiła Kupcewicz
    • Oleksiy Khavryuchenko
    • Barbara Barszcz
    2020 CRYSTENGCOMM

    To evaluate the impact of the flexible positional isomeric ligands thiophene-2-acetate (2tpacCOO) andthiophene-3-acetate (3tpacCOO) on the construction and self-assembly process of Pb(II) polymers, twonovel compounds, [Pb(2tpacCOO)2(H2O)]n(1) and [Pb(3tpacCOO)2]n(2), were preparedviaanonhydro-thermal method with respect to green chemistry rules. The obtained polymers were fully characterized byelemental analysis, TG/DTG and PXRD, FT-IR, solid-state photoluminescence, DFT calculations and single-crystal X-ray diffraction. Each Pb(II)centreof1is 7-coordinated as a {PbO7} chromophore while the Pb(II)centre of2is 6-coordinated as a {PbO6} structure. The coordination polyhedron of1is best described as adistorted monocapped pentagonal pyramid, and2has a distorted trigonal prismatic shape. The crystallo-graphic analysis and DFT calculations indicated the stereoactivity of the lone electron pair, which contrib-uted to the hemidirected geometry of the Pb(II) environment. Due to the versatile binding modes of the li-gands, complex1forms 1D stair-like chains with an SP 1-periodic net (4,4)(2,0) topology, and theunderlying net of2is determined to have a 1D 2,4C4 topology. It is worth noting that the crystal structuresof the obtained polymers are stabilized mainly by many hydrogen bonds as well as Pb⋯SandPb⋯πtetrelinteractions. Moreover, the PL data demonstrate the different influences of the isomers of linkers onphotoluminescence properties. Polymer1might be a good candidate for obtaining solid-state photo-luminescent materials.