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Gdańsk University of Technology

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Publications from the year 2020

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  • Service-based Resilience for Embedded IoT Networks
    • Doganalp Ergenc
    • Jacek Rak
    • Mathias Fischer
    2020

    Embedded IoT networks are the backbone of safety-critical systems like smart factories, autonomous vehicles, and airplanes. Therefore, resilience against failures and attacks should be a prior concern already in their design stage. In this study, we introduce a service-based network model as an MILP optimization problem for the efficient deployment of a service overlay to the embedded network by meeting QoS and resilience requirements. We show the complexity and boundaries of the problem and propose several heuristics to relax the service deployment phase and increase the fault-tolerance against node and link failures. Our results indicate that the heuristics achieve results close to the optimum for small sizes of the problem with up to 10^8 time faster solution time. We also show that the heuristics can solve larger problem sizes and can maintain the service availability for 85% of all potential single node failures.

  • SERVICE-ORIENTED CYBERSPACE FOR IMPROVING CYBERSECURITY
    • Henryk Krawczyk
    2020 Full text TASK Quarterly

    The paper presents a cyberspace model where different categories of IT services are offered and used largely. A general cybersecurity policy is considered and the corresponding cybersecurity strategies are shown. The role of such technologies as: Internet of Things, Cloud Computing and Big Data is analyzed in order to improve the cybersecurity of a cyberspace. A new kind of service oriented cyberspace is proposed and its main properties are emphasized. Two simple examples of such cyberspaces are given and briefly discussed.

  • Set of Experience and Decisional DNA: Experience-Based Knowledge Structures
    • Cesar Sanin
    • Edward Szczerbicki
    2020

    This chapter presents a description of Set of Experience Knowledge Structure (SOEKS) and Decisional DNA (DDNA), argumentation for a knowledge representation, composition, configuration and metrics. SOEKS is a combination of filtered and amalgamated information obtained from formal decision events. It facilitates effective explicit representation of decisional experience taken from different technologies. SOEKS comprises variables, functions, constraints and rules associated in a DNA shape, allowing the construction of enterprises’ fingerprints called Decisional DNA. SOEKS possesses characteristics that potentialize it as a more precise knowledge representation in a world guided by sensitive dependence and uncertainty, that is, SOEKS is a suitable representation for decisional explicit knowledge that has been gifted with capabilities to manage uncertainty, preciseness and incompleteness. Furthermore, SOEKS extends into the so-called DDNA due to the characterization and aggrupation of SOEKS into different classes termed decisional chromosomes. Such decisional chromosomes simulate specialized genes that when placed together create the decisional experience of an enterprise, the Decisional DNA.

  • SEWAGE SYSTEM CONCEPT FOR KAMIEŃ VILLAGE IN THE COMMUNE OF SZEMUD
    • Dominika Grubba
    2020

    The aim of this thesis is to solve a disturbing problem, which is illegal sewage discharge, without any previous treatment in a village Kamień, Szemud commune, Poland, by developing a multivariate sewerage system concept. The introduction submits the theory concerning the division of sewer systems as well as the wastewater treatment’s level. Moreover, there is also the problem of rural sanitation presented and main locality – Kamień description. Furthermore, two variants of the sewage network, meaning: one, that is connecting to an existing network in the village and second one, that is discharging wastewater into the local sewage treatment plant are precisely defined. Calculation part presents all necessary steps to select sewagetubes and wastewater treatment plants. Lastly, there is also a graphic summary of entire solution for the village Kamień presented in this work.

  • Shading, Dusting and Incorrect Positioning of Photovoltaic Modules as Important Factors in Performance Reduction
    • Ewa Klugmann-Radziemska
    2020 Full text ENERGIES

    The amount of solar radiation reaching the front cover of a photovoltaic module is crucial for its performance. A number of factors must be taken into account at the design stage of the solar installation, which will ensure maximum utilization of the potential arising from the location. During the operation of a photovoltaic installation, it is necessary to limit the shading of the modules caused by both dust and shadowing by trees or other objects. The article presents an analysis of the impact of the radiation reaching the surface of the radiation module on the efficiency obtained. Each of the analyzed aspects is important for obtaining the greatest amount of energy in specific geographical conditions. Modules contaminated by settling dust will be less efficient than those without deposits. The results of experimental studies of this effect are presented, depending on the amount of impurities, including their origins and morphologies. In practice, it is impossible to completely eliminate shadowing caused by trees, uneven terrain, other buildings, chimneys, or satellite dishes, and so on, which limits the energy of solar radiation reaching the modules. An analysis of partial shading for the generated power was also carried out. An important way for maximizing the incoming radiation is the correct positioning of the modules relative to the sun. It is considered optimal to position the modules relative to the light source, that is, the sun, so that the rays fall perpendicular to the surfaces of the modules. Any deviation in the direction of the rays results in a loss in the form of a decrease in the available power of the module. The most beneficial option would be to use sun-tracking systems, but they represent an additional investment cost, and their installations require additional space and maintenance. Therefore, the principle was adopted that stationary systems should be oriented to the south, using the optimal angle of inclination of the module surface appropriate for the location. This article presents the dependence of the decrease in obtained power on the angle of deviation from the optimal one.

  • Shallow Water Equations as a Mathematical Model of Whitewater Course Hydrodynamics
    • Michał Szydłowski
    • Patrycja Mikos-Studnicka
    2020 GeoPlanet: Earth and Planetary Sciences

    Predicting the positions of local hydraulic phenomena, as well as accurately esti-mating the depth and velocity of the water flow are necessary to correctly config-ure a whitewater canoeing course. Currently, a laboratory and full 3D CFD model-ing are typically used in the design process to meet these needs. The article points to another possibility which can be useful at the preliminary stage of the design. The authors show that a mathematical model of depth-averaged free-surface flow can reliably predict the basic flow dynamics and location of some hydraulic local effects within a whitewater open channel. The results of a numerical simula-tion of the transcritical flow were compared to the flow parameters measured in a laboratory model of a constriction in an open-channel flow. A satisfactory agreement between the measurements and calculated flow parameters was ob-served along with the proper reconstruction of hydraulic local effects. It can be concluded that the proposed simplified approach to modeling is an efficient method to investigate the main hydraulic features of whitewater flow needed at the concept stage of the design process. This means that cost and time-consuming laboratory and CFD modeling is necessary only at a later stage of the design, after the initial concept of the canoe course has been completed.

  • Shallow Water Experiment of OFDM Underwater Acoustic Communications
    • Iwona Kochańska
    • Jan Schmidt
    • Jacek Marszal
    2020 Full text Archives of Acoustics

    The large variability of communication properties of underwater acoustic channels, and especially the strongly varying instantaneous conditions in shallow waters, is a challenge for the designers of underwater acoustic communication (UAC) systems. The use of phase modulated signals does not allow reliable data transmission through such a tough communication channel. However, orthogonal frequency-division multiplexing (OFDM), being a multi-carrier amplitude and phase modulation technique applied successfully in the latest standards of wireless communications, gives the chance of reliable communication with an acceptable error rate. This paper describes communication tests conducted with the use of a laboratory model of an OFDM data transmission system in a shallow water environment in Wdzydze Lake.

  • Shape memory thin films of Polyurethane: Does graphene content affect the recovery behavior of Polyurethane nanocomposites?
    • Maryam Zarghami Dehaghani
    • Babak Kaffashi
    • Józef Haponiuk
    • Łukasz Piszczyk
    2020 POLYMER COMPOSITES

    Thin nanocomposite films of polyurethane have received remarkable attention due to their shape memory properties. As most of the reports focus on the beneficial aspects of the presence of nanofillers such as graphene nanoplatelets (GNPs) introduced into shape memory polymers, some research results reveal the opposite trend. The polyether/polyester-based polyurethane was synthesized through a condensation polymerization and the nanocomposite films containing 0.1, 0.25, 0.5, and 1 wt.% of GNPs were prepared by the solvent casting method. The Fourier transformed infrared (FTIR) spectroscopy was carried out to investigate the chemical structure of nanocomposite films. The properties of nanocomposite films were verified by the differential scanning calorimetry (DSC), X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), tensile test, and the dynamic mechanical analysis (DMA). The shape memory properties were studied through various thermomechanical cycles applied by the DMA apparatus. All the nanocomposite films showed larger glassy storage moduli compared with those of the neat PU films. The nanocomposite film containing 0.25 wt.% GNPs showed the highest shape recovery ratio (92.4%) since the net-point effect of GNPs dominates its slipping effect. While for the other nanocomposite films the slippage effect overcomes the net-point effect.

  • Shaping the competence of future spatial policymakers for small- and medium-sized towns
    • Piotr Lorens
    • Anna Golędzinowska
    2020 Full text World Transactions on Engineering and Technology Education

    In this article, the authors aim to present issues addressed within the framework of the architecture and spatial development courses offered by the Faculty of Architecture at Gdańsk University of Technology (FA-GUT), Gdańsk, Poland. These issues concern competence in the education of future spatial planners and their readiness to deal with the development challenges facing small- and medium-sized towns. Within the article, the similarities and differences are pointed out that relate to curriculum structure and academic outcomes that can influence the professional profile of graduates. Similarities between the two courses enable identification of the most effective model. The article includes a summary of the educational problem, an outline of design studio profiles for both courses, comparison of the results achieved and conclusions regarding future educational efforts, including relevant lessons for other planning and engineering schools. The conclusions focus on the lessons learnt and suggest improvements that can be made worldwide within educational programmes.

  • Shared processor scheduling of multiprocessor jobs
    • Dariusz Dereniowski
    • Wiesław Kubiak
    2020 EUROPEAN JOURNAL OF OPERATIONAL RESEARCH

    We study a problem of shared processor scheduling of multiprocessor weighted jobs. Each job can be executed on its private processor and simultaneously on possibly many processors shared by all jobs. This simultaneous execution reduces their completion times due to the processing time overlap. Each of the m shared processors may charge a different fee but otherwise the processors are identical. The goal is to maximize the total weighted overlap of all jobs. This is a key problem in subcontractor scheduling in extended enterprises and supply chains, and in divisible load scheduling in computing. We introduce synchronized schedules that complete each job that uses some shared processor at the same time on its private and on the shared processors. We prove that, quite surprisingly, the synchronized schedules include optimal ones. We obtain an α-approximation algorithm that runs in strongly polynomial time for the problem, where α = 1/2 + 1/(4(m+1)). This improves the 1/2-approximation reported recently in the literature to 5/8-approximation for a single shared processor problem, m=1. The computational complexity of the problem, both in case of single and multi-shared processor, remains open. We show however an LP-based optimal algorithm for antithetical instances where for any pair of jobs j and i, if the processing time of j is smaller than or equal to the processing time of i, then the weight of j is greater than or equal to the weight of i.

  • Shear Cap Size Selection Method Based on Parametric Analysis of ACI-318 Code and Eurocode 2 Standard
    • Maciej Grabski
    • Andrzej Ambroziak
    2020 Full text Materials

    The scope of the paper is to propose a method for determining the size of shear caps in a slab–column-connections-reinforced concrete structure. Usually, shear heads are used to enhance slab–column connection, especially when the transverse reinforcement does not give the required punching shear load capacity. The dimensions of the shear head should provide the punching shear resistance of the connection inside and outside the enhanced region. The process of selecting the size of the shear head is iterative. The parametric analysis of the ACI 318 code and EC2 standard has the objective of indicating which control perimeter (inside or outside the shear head) has a decisive impact on the punching shear capacity of the connection. Based on the analysis, the authors propose methods for selecting the dimensions of the shear head with practical application examples. The paper is intended to provide scientists, civil engineers, and designers with guidelines to design the process of the slab–column connections with the shear caps.

  • Shear resistance of low height precast concrete lintels
    • Andrzej Ambroziak
    • Jarosław Kondrat
    • Marek Wesołowski
    2020 Full text Archives of Civil Engineering

    The scope of the paper is to investigate analytically and determine experimentally the shear resistance of low height reinforced precast concrete lintels. The chosen procedures included in national and international standards applied for the design of structural concrete elements to an estimation of shear behaviour of reinforced concrete elements are described. The characteristic and designed shear strength of precast concrete lintels are determined and compared with experimentally obtained results. The shear resistance for precast concrete lintels was determined by laboratory tests according to a European standard. The assessment of the in-situ compressive strength of concrete in precast concrete lintel is specified. The designed compressive strength class is confirmed. The real reinforcement distribution is verified to assess the wide scatter of experimentally obtained failure forces. A short literature outlook of the papers concerning investigations on lintels and shear resistance of concrete is given also. The paper can provide scientists, engineers, and designers a theoretical and experimental basis in the field of precast concrete lintels shear resistance.

  • Short and Long Term Measurements in Assessment of FRP Composite Footbridge Behavior
    • Mikołaj Miśkiewicz
    • Łukasz Pyrzowski
    • Bartosz Sobczyk
    2020 Full text Materials

    The paper presents application of different sensors for the purpose of short and long term measurements, as well as a structural health monitoring (SHM) system to assess the behavior of a novel fiber reinforced plastics (FRP) composite footbridge. The aim is to present a thorough and concise description of these sensors networks and results gathered with their aid during in situ measurement of strains, displacements, and vibrations, as only a few works are available in this field. The bridge geometry, material solutions, and properties are described at first. Then the measurement devices composing the system and subsystems of sensors are elaborated on. Subsequently, the bridge research program is described and the results are shown and discussed. Finally, it is concluded that the use of selected sensors is helpful in assessment of the behavior of the novel structure, and moreover in validation of its numerical models. The collected data confirmed many assumptions made during the bridge design process and allowed us to accept it for exploitation.

  • SHORT REVIEW AND 3-D FEM ANALYSIS OF BASIC TYPES OF FOUNDATION FOR OFFSHORE WIND TURBINES
    • Piotr Iwicki
    • Jarosław Przewłócki
    2020 Full text Polish Maritime Research

    Some problems of the foundations of offshore wind turbines are considered in this paper. A short review is presented on the two basic types of foundations, i.e. monopiles and gravity foundations, including their basic features and applications as well as general design considerations. Also, some issues regarding analysis are discussed, including geotechnical problems and modelling techniques. A numerical model of offshores turbine and some preliminary computations are presented. Finite element analysis was carried out for wind turbines supported on both gravity and monopile foundations. The wind turbine tower, blades (simplified model), gravity foundation and part of the surrounding soil are included in the model. The turbine was loaded by wind and loads induced by waves, inertia and gravity. Both non-linear static and dynamic analysis of the wind turbine was performed. The displacements and stresses under the tower foundations were calculated and a comparison analysis carried out.

  • Short-range order structure and free volume distribution in liquid bismuth: X-ray diffraction and computer simulations studies
    • Valeriy Plechystyy
    • Ihor Shtablavyi
    • Szymon Winczewski
    • Kamil Rybacki
    • Stepan Mudry
    • Jarosław Rybicki
    2020 PHILOSOPHICAL MAGAZINE

    The structure of liquid bismuth was studied by X-ray diffraction and computer simulation methods. The contraction of the atomic structure within the first coordination sphere in the temperature interval of 575- 1225 K is reported. The temperature dependencies of the coordination numbers and of the free volume are analysed. On the basis of the temperature dependencies of the free volume, the temperature dependencies of viscosity and the self-diffusion coefficient were calculated to be in the ranges from 1.17 to 0.86 mPa s and from 2.18 × 10 −9 to 5.44 × 10 −9 m 2 /s, respectively. The free volume – extracted results are in fair agreement with the experimental data and with the results obtained in the molecular dynamics simulations

  • Short-term Price Reaction to Involuntary Bankruptcies Filed in Bad Faith: Empirical Evidence from Poland
    • Błażej Prusak
    • Marcin Potrykus
    2020 Full text European Research Studies Journal

    Purpose: Assessing the reaction of the prices of shares of companies listed in the Warsaw Stock Exchange to the public disclosure of information about the filing a bankruptcy petition in bad faith by creditors. Design/Methodology/Approach: Event study analysis. Findings: It can therefore be assumed that the filing of an unfounded bankruptcy petition does not, in the short term, have a statistically significant negative impact on the share price of the company being the subject of the petition Practical Implications: When information about the filing a bankruptcy petition appears and creditors submitted it in bad faith, it has not a negative impact on the share price in short term. It can be said that submitting such information is not an opportunity for an investor to receive an abnormal rate of return. Originality/value: Although there are many research results using event study analysis most of them are related to the US market. The originality of this paper is that this research is dedicated to petitions in bad faith for a selected developing country.

  • Shoulder ultrasound in the diagnosis of the suprascapular neuropathy in athletes
    • Barbara Igielska-Bela
    • Boguslaw Baczkowski
    • Karol Flisikowski
    2020 Full text Open Medicine

    Purpose: Shoulder pain and weakness are common symptoms in athletes who play sports connected with overhead throwing. Suprascapular neuropathy may be one of the reason of such signs.The aim of the study was to find out if ultrasound examination of the shoulder in athletes reveals signs of suprascapular neuropathy. Methods: This was a cross-sectional study in which 67 pro- fessional volleyball, handball and rugby players of polish teams without shoulder disorders, which have played sport for 10 or more years, were included. An ultrasound examination of both shoulders was performed. Exclud- ing criteria were recent shoulder and/or neck trauma and neurological disorders. Results: No ultrasound signs of suprascapular neuropathy were seen in any player. The only finding was enthesop- athy of supraspinatus muscle and this finding was con- nected with athletes’ age, type of sport and with dominant hand. It had statistical significance with p-value respec- tively 0.01 for athletes’ age, 0.0208 for sport type and 0.03 for dominant hand. Conclusions: Ultrasonography should not be used as the screening examination of shoulders in athletes, but it can sometimes be an additional tool to help to diagnose shoul- der disorders.

  • SiC-Based Power Electronic Traction Transformer (PETT) for 3 kV DC Rail Traction
    • Marek Adamowicz
    • Janusz Szewczyk
    2020 Full text ENERGIES

    The design of rolling stock plays a key role in the attractiveness of the rail transport. Train design must strictly meet the requirements of rail operators to ensure high quality and cost-eective services. Semiconductor power devices made from silicon carbide (SiC) have reached a level of technology enabling their widespread use in traction power converters. SiC transistors oering energy savings, quieter operation, improved reliability and reduced maintenance costs have become the choice for the next-generation railway power converters and are quickly replacing the IGBT technology which has been used for decades. The paper describes the design and development of a novel SiC-based DC power electronic traction transformer (PETT) intended for electric multiple units (EMUs) operated in 3 kV DC rail traction. The details related to the 0.5 MVA peak power medium voltage prototype, including the electrical design of the main building blocks are presented in the first part of the paper. The second part deals with the implementation of the developed SiC-based DC PETT into a regional train operating on a 3 kV DC traction system. The experimental results obtained during the testing are presented to demonstrate the performance of the developed 3 kV DC PETT prototype.

  • Signal propagation in electromagnetic media described by fractional-order models
    • Tomasz Stefański
    • Jacek Gulgowski
    2020 Communications in Nonlinear Science and Numerical Simulation

    In this paper, signal propagation is analysed in electromagnetic media described by fractional-order (FO) models (FOMs). Maxwell’s equations with FO constitutive relations are introduced in the time domain. Then, their phasor representation is derived for one-dimensional case of the plane wave propagation. With the use of the Fourier transformation, the algorithm for simulation of the non-monochromatic wave propagation is introduced. Its implementation in Matlab allows for generation of time-domain waveforms of signals propagating in the media described by FOMs. It is demonstrated that despite high attenuation, a small perturbation of the time-derivative orders in Maxwell’s equations allows for tuning of the time of signal arrival to the observation point. In all the cases studied, the rate of pulse advancement increases, with simultaneous decrease of the value of the time-derivative orders in FO Maxwell’s equations.

  • Signature of Oxide-Ion Conduction in Alkaline-Earth-Metal-Doped Y3GaO6
    • Pragati Singh
    • Raghvendra Pandey
    • Tadeusz Miruszewski
    • Kacper Dzierzgowski
    • Aleksandra Mielewczyk-Gryń
    • Prabhakar Singh
    2020 Full text ACS Omega

    We have studied alkaline-earth-metal-doped Y3GaO6 as a new family of oxide-ion conductor. Solid solutions of Y3GaO6 and 2% −Ca2+-, −Sr2+-, and −Ba2+-doped Y3GaO6, i.e., Y(3−0.06)M0.06GaO6−δ (M = Ca2+, Sr2+, and Ba2+), were prepared via a conventional solid-state reaction route. X-ray Rietveld refined diffractograms of all the compositions showed the formation of an orthorhombic structure having the Cmc21 space group. Scanning electron microscopy (SEM) images revealed that the substitution of alkaline-earth metal ions promotes grain growth. Aliovalent doping of Ca2+, Sr2+, and Ba2+ enhanced the conductivity by increasing the oxygen vacancy concentration. However, among all of the studied dopants, 2% Ca2+-doped Y3GaO6 was found to be more effective in increasing the ionic conductivity as ionic radii mismatch is minimum for Y3+/Ca2+. The total conductivity of 2% Ca-doped Y3GaO6 composition calculated using the complex impedance plot was found to be ∼0.14 × 10−3 S cm−1 at 700 °C, which is comparable to many other reported solid electrolytes at the same temperature, making it a potential candidate for future electrolyte material for solid oxide fuel cells (SOFCs). Total electrical conductivity measurement as a function of oxygen partial pressure suggests dominating oxide-ion conduction in a wide range of oxygen partial pressure (ca. 10−20−10−4 atm). The oxygen-ion transport is attributed to the presence of oxygen vacancies that arise from doping and conducting oxide-ion layers of one, two-, or three-dimensional channels within the crystal structure. The oxide-ion migration pathways were analyzed by the bond valence site energy (BVSE)-based approach. Photoluminescence analysis, dilatometry, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy studies were also performed to verify the experimental findings.