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Politechniki Gdańskiej

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  • Improved RSS-Based DoA Estimation Accuracy in Low-Profile ESPAR Antenna Using SVM Approach
    • Michał Tarkowski
    • Mateusz Burtowy
    • Mateusz Rzymowski
    • Krzysztof Nyka
    • Mateusz Groth
    • Łukasz Kulas
    2019 Pełny tekst

    In this paper, we have shown how the overall performance of direction-of-arrival (DoA) estimation using lowprofile electronically steerable parasitic array radiator (ESPAR) antenna, which has been proposed for Internet of Things (IoT) applications, can significantly be improved when support vector machine (SVM) approach is applied. Because the SVM-based DoA estimation method used herein relies solely on received signal strength (RSS) values recorded at the antenna output port for different directional radiation patterns produced by the antenna steering circuit, the algorithm is wellsuited for IoT nodes based on inexpensive radio transceivers. Measurement results indicate that, although the antenna can provide 8 unique main beam directions, SVM-based DoA of unknown incoming signals can successfully be estimated with good accuracy in a fast way using limited number of radiation patterns. Consequently, such an approach can be used in efficient location-based security methods in Industrial Internet of Things (IIoT) applications.

  • Improvement of ships seakeeping performance by application of the Full-scale CFD simulations – case study
    • Karol Niklas
    • Hanna Pruszko
    2019

    The ship’s fuel economy is increasingly important. The paper presents the effect of redesigning a case study ship for increasing seakeeping performance. Selected wave parameters reflects very difficult operational con-ditions existing on the North Sea and the Baltic Sea. The analyzed variants of a case study ship represent the latest developments of modern hull forms. The concepts similar to V-shaped bulbous bow, X-bow, X-aft, B-bow were adopted. Full-scale CFD simulations were performed to analyze the influence of innovative hull forms on the added resistance, heave and pitch motions for head waves and two vessel speeds. It was found that with the use of Full-scale CFD simulations it is possible to capture phenomena that cause ship’s non-linear behavior. The calculated relation between added resistance and ships’ vertical motions was opposite to linear strip theory. It proves that the results obtained by linear strip theory method and the CFD can differ signifi-cantly.

  • Improvement of the load capacity of the road overpass as a result of repairs after breakage caused by vehicle impacts
    • Mikołaj Miśkiewicz
    • Dawid Bruski
    • Jacek Chróścielewski
    • Krzysztof Wilde
    2019 Pełny tekst MATEC Web of Conferences

    Damage of spans of the overpass caused by impact of underpassing vehicles are a frequent case. Objects that use prefabricated load-bearing elements that are not designed for such impacts are particularly exposed. After impact, such parts suffer extensive damage that need repair. Taking advantages of this recovery actions it is worth to perform strengthening that will protect object against possible future impacts. In this study the influence of the structural strengthening of the damaged overpass on its strength parameters is investigated. For this purpose the advanced computational model was created. The model includes reinforcement and prestressing tendons. This model enables reliably restore damage caused due to the vehicle's impact and analysing of re-impact the strengthened structure. The damage of the concrete and deformation of the reinforcement is presented.

  • Improvements to the two-phase sandwich method for calculating the melting points of pure metals
    • Kamil Rybacki
    • Valeriy Plechystyy
    • Szymon Winczewski
    • Jarosław Rybicki
    2019 Pełny tekst Computational Methods in Science and Technology

    The thermophysical properties of metal alloys are often investigated via molecular dynamics (MD) simulations.An exact and reliable estimation of the thermophysical parameters from the MD data requires a properly and carefullyelaborated methodology. In this paper, an improved two-phase sandwich method for the determination of the metal meltingtemperature is proposed, based on the solid-liquid equilibrium theory. The new method was successfully implemented usingthe LAMMPS software and the C++11 Standard Libraries and then applied to aluminum and copper systems. The resultsshow that the proposed procedure allows more precise calculations of the melting temperature than the widely used one-phase boundary methods.

  • Improving Accuracy of Contactless Respiratory Rate Estimation by Enhancing Thermal Sequences with Deep Neural Networks
    • Alicja Kwaśniewska
    • Jacek Rumiński
    • Maciej Szankin
    2019 Pełny tekst Applied Sciences-Basel

    Estimation of vital signs using image processing techniques have already been proved to have a potential for supporting remote medical diagnostics and replacing traditional measurements that usually require special hardware and electrodes placed on a body. In this paper, we further extend studies on contactless Respiratory Rate (RR) estimation from extremely low resolution thermal imagery by enhancing acquired sequences using Deep Neural Networks (DNN). To perform extensive benchmark evaluation, we acquired two thermal datasets using FLIR® cameras with a spatial resolution of 80 × 60 and 320 × 240 from 71 volunteers in total. In-depth analysis of the proposed Convolutional-based Super Resolution model showed that for images downscaled with a factor of 2 and then super-resolved using Deep Learning (DL) can lead to better RR estimation accuracy than from original high-resolution sequences. In addition, if an estimator based on a dominating peak in the frequency domain is used, SR can outperform original data for a down-scale factor of 4 and images as small as 20 × 15 pixels. Our study also showed that RR estimation accuracy is better for super-resolved data than for images with color changes magnified using algorithms previously applied in the literature for enhancing vital signs patterns.

  • Improving SBR Performance Alongside with Cost Reduction through Optimizing Biological Processes and Dissolved Oxygen Concentration Trajectory
    • Robert Piotrowski
    • Aleksander Paul
    • Mateusz Lewandowski
    2019 Pełny tekst Applied Sciences-Basel

    Authors of this paper take under investigation the optimization of biological processes during the wastewater treatment in sequencing batch reactor (SBR) plant. A designed optimizing supervisory controller generates the dissolved oxygen (DO) trajectory for the lower level parts of the hierarchical control system. Proper adjustment of this element has an essential impact on the efficiency of the wastewater treatment process as well as on the costs generated by the plant, especially by the aeration system. The main goal of the presented solution is to reduce the plant energy consumption and to maintain the quality of effluent in compliance with the water-law permit. Since the optimization is nonlinear and includes variations of different types of variables, to solve the given problem the authors performed simulation tests and decided to implement a hybrid of two different optimization algorithms: artificial bee colony (ABC) and direct search algorithm (DSA). Simulation tests for the wastewater treatment plant case study are presented.

  • IMPROVING STUDENT SKILLS WITH ENGAGING IN HERITAGE PROTECTION PROJECTS. CASE STUDY OF ARCHITECTURAL INVENTORY WORKS AT WISŁOUJŚCIE FORTRESS, POLAND (2017)
    • Waldemar Ossowski
    • Tadeusz Widerski
    • Joanna Dąbal
    • Maciej Flis
    2019

    Today's educational offer at universities contains a lot of theoretical and general knowledge, which becomes less understandable and less suitable for students of the new generation. Student's educational needs aimed at increasing the practical experience necessary for future professional life. Heritage conservation projects are a good opportunity to implement project-based learning methods. Such projects can be scientific and technical research. In 2017, as part of the cooperation of the Gdańsk Museum, the University of Gdańsk and the Gdańsk University of Technology, pilot interdisciplinary research activities were undertaken in the Wisłoujście Fortress in Poland. The project includes an innovative educational path aimed at implementing new digital documentation methods, standard academic research of monuments and gathering archival information. The first tasks were focused on architectural inventory and archaeological research in the post-medieval area. The main purpose of these proceedings was the preliminary functional interpretation of the interiors studied. A lot of new data was collected that explained the unknown building history. Students were trained in the field of measurement systems, photogrammetric documentation and the history of building materials. In addition, students processed data by creating 3D models of documented structures. All implemented activities were aimed at involving the students of both institutions in the history of the Wisłoujście Fortress. Participation in the implementation of "real" tasks contributed to the greater involvement of participants. The works they carried out were additionally disseminated in social media, initiating an open public debate on the subject of military heritage. Implementation of the monument protection project on the example of the Wisłoujście Fortress showed that through appropriate involvement of students from various scientific units, the impact range and effectiveness of the project implementation can be improved, the methods of learning students can be improved as well as the results of the works can be disseminated more widely.

  • Impulse Impedance Measurements of Lightning Protection Earthings
    • T. Horchue
    • W. Tangtheerajaroonwong
    • Stanisław Wojtas
    • Marek Wołoszyk
    2019

    Lightning protection earthing systems should be tested at currents with time parameters similar to those of lightnings. A method and definition of a measured value of impulse impedance are introduced. The impulse impedance was determined by a quotient of voltage drop on the tested earthing to a value of current in measure circuit. The usefulness of the impulse method for lightning protection evaluation is tested on radio base stations tower, transmission line towers, and buildings. Application of the earthing impulse meter is described in this paper.

  • In search of a common ground for the space sciences
    • Edmund Wittbrodt
    • Zdzisław Brodecki
    2019

    The paper discusses the relations between various aspects of human activities performed in space, taking into consideration the past, present and future contexts. Interdisciplinarity and integrity of technological issues combined with legal and management issues were emphasized. Consequently, it was recognized that it is necessary to build a network of universities, research-and-development companies and engineering companies. A particular attention was dedicated to the current situation in Poland and conditions necessary to achieve a European level.

  • In situ study of a composition of outlet gases from biogas fuelled Solid Oxide Fuel Cell performed by the Fourier Transform Infrared Spectroscopy
    • Mikołaj Chlipała
    • Patryk Błaszczak
    • Sea-Fue Wang
    • Piotr Jasiński
    • Beata Bochentyn
    2019 Pełny tekst INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

    The purpose of this study was to develop a method and software based on the Fourier Transform Infrared Spectroscopy for the in-situ, quantitative analysis of the composition of outlet gases from Solid Oxide Fuel Cell (SOFC). The calibration procedure performed at the beginning of the experiment indicated a polynomial dependence between the concentration of a calibrating gas (CO, CO2, CH4) and the corresponding integrated absorbance in particular wavenumber ranges. Further, it allowed determining a concentration of CO2, CO, CH4 and H2 in the outlet gas stream of the Ni-YSZ anode supported Direct Internal Reforming-SOFC fuelled by synthetic biogas (mixture of CO2 and CH4 in a volume ratio 2:3). The analysis was performed for over 90 h. Based on calculated concentration the conversion rates for both CH4 and CO2 gases were calculated, as well as the yields and selectivities of CO and H2. Also, the carbon balance was determined. In order to predict the direction of particular reforming reactions, a non-equilibrium analysis was performed. Namely, a thermodynamic probability of solid carbon formation was determined based on calculations of carbon activity coefficients. Obtained results indicated degradation of a fuel cell and corresponded well with electrical measurements where a decrease of power density in wet synthetic biogas was observed.

  • In Situ Verification of Numerical Model of Water Hammer in Slurries
    • Apoloniusz Kodura
    • Katarzyna Weinerowska-Bords
    • Wojciech Artichowicz
    • Michal Kubrak
    • Pawel Stefanek
    2019 Pełny tekst JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME

    This paper presents a numerical model of transient flow in a pressure slurry pipeline network with verification based on in situ measurements. The model, primarily verified in laboratory conditions, has been extended and applied to the case of a large and complex slurry pipeline network in Poland. In the model, the equivalent density concept was applied. In situ experiments were performed for various unsteady flow episodes, caused by different pump operation strategies in the industrial pipeline network. Based on the measurements of slurry concentration and pressure variations, the numerical model was tested and verified. A satisfactory coincidence between the calculated and the observed pressure characteristics was achieved. Additional numerical tests led to important conclusions concerning safe pump and valve operation and system security threats.

  • Incorporating Iris, Fingerprint and Face Biometric for Fraud Prevention in e-Passports Using Fuzzy Vault
    • Katarzyna Bobkowska
    • Khaled Ahmed Nagati
    • Marek Przyborski
    2019 Pełny tekst IET Image Processing

    A unified frame work which provides a higher security level to e-passports is proposed. This framework integrates face, iris and fingerprint images. It involves three layers of security: the first layer maps a biometric image to another biometric image which is called biostego image. Three mapping schemes are proposed: the first scheme maps single biometric image to single biostego image, the second scheme maps dual biometric images to single biostego image, the third scheme divides the biometric image into sections and maps each section to different biostego image. A mapping function maps the intensity value of each pixel in the biometric image to pixels with same intensity in the biostego image. A representative pixel is randomly selected from the set of pixels, its coordinates are recorded in the location map of the biometric image. In the second layer, the location map is encoded using fingerprint fuzzy vault. In the third layer, the encoded location map is hidden in the biostego image using steganography technique. The biostego image which contains the encoded location map is stored in the e-passport’s memory. Keeping the mapping scheme secret and by using the fingerprints fuzzy vault to encrypt location map the proposed approach provides higher level of protection against fraud.

  • Increasing K-Means Clustering Algorithm Effectivity for Using in Source Code Plagiarism Detection
    • Patrik Hrkút
    • Michal Ďuračík
    • Miroslava Mikušová
    • Mauro Callejas-cuervo
    • Joanna Żukowska
    2019

    The problem of plagiarism is becoming increasingly more significant with the growth of Internet technologies and the availability of information resources. Many tools have been successfully developed to detect plagiarisms in textual documents, but the situation is more complicated in the field of plagiarism of source codes, where the problem is equally serious. At present, there are no complex tools available to detect plagiarism in a large number of software projects, such as student projects, which are created hundreds per year at each faculty of informatics. Our project aim is to create such a system for finding plagiarism in a large dataset of source codes. The whole system consists of several parts. A classification of source code is an essential part of the whole system because it makes it much more efficient to manipulate source code and divide data into individual clusters so that searching in large volumes of source code is as efficient as possible. The paper discusses how to optimize the implementation of clustering, so the whole system would deliver results in a reasonable time because allocating the different parts of the source code into suitable clusters will allow faster and more memory-efficient search for similar parts of the code.

  • Increasing the Seismic Resistance of Wood-frame Buildings by Applying PU Foam as Thermal Insulation
    • Wojciech Migda
    • Marcin Szczepański
    • Robert Jankowski
    2019 Pełny tekst Periodica Polytechnica-Civil Engineering

    Wood-frame buildings are very common in regions that are exposed to earthquakes. Most of residential buildings are constructed using this technology; therefore, the seismic resistance of them is really essential in order to prevent human losses and structural damage. The aim of the present article is to show the results of the detailed numerical FEM analysis focused on the seismic behaviour of the wood-frame house with different in-wall insulation materials. The results of the study clearly indicate that using polyurethane (PU) foam instead of mineral wool leads to the increase in the rigidity of the structure and, therefore, to the substantial reduction in the structural response under different seismic excitations. The results also show that, generally speaking, the level of reduction in the displacement response increases with the increase in the magnitude of the earthquake, which even furthermore benefits the application of PU foam as an insulation material. It has also been concluded that the method of using PU foam can be successfully applied not only in the newly constructed wood-frame houses but also in existing ones since replacing the mineral wool with PU foam is relatively easy and not so much expensive.

  • In-depth characterization of icosahedral ordering in liquid copper
    • Szymon Winczewski
    • Jacek Dziedzic
    • Jarosław Rybicki
    2019 Pełny tekst COMPUTATIONAL MATERIALS SCIENCE

    The presence of icosahedral ordering in liquid copper at temperatures close to the melting point is now well-established both experimentally and through computer simulation. However, a more elaborate analysis of local icosahedral and icosahedron-like structures, together with a system for classifying such structures based on some measure of "icosahedrity", has so far been conspicuously absent in the literature. Similarly, the dynamics of these structures has not yet received the attention it merits. We present a new method for structural analysis, which combines Voronoi analysis with bond-orientational order parameters, and apply it to liquid Cu configurations obtained from tight-binding molecular dynamics at a range of temperatures near the melting point. We introduce a clear system for classifying local structures according to their degree of similarity to the perfect icosahedron, and show how their energies of formation correlate with our structural descriptor. We examine the frequencies of occurrence for the classes of Voronoi polyhedra we distinguish, calculate their lifetimes, and establish the temperature dependence of these properties. We explore the dynamics of icosahedron-like structures by examining how individual classes transform between one another. Finally, we perform structural correlation analysis, demonstrating, among other things, that icosahedra and icosahedron-like structures preferentially connect and show a tendency towards clustering. We believe our approach can be readily applied in studies of icosahedral ordering in liquid metals or metallic glasses.

  • Induction of chirality in 4,4'-azopyridine by halogen-bonding interaction with optically active ditopic donors
    • Jan Alfuth
    • Jarosław Chojnacki
    • Tadeusz Połoński
    • Teresa Olszewska
    2019 NEW JOURNAL OF CHEMISTRY

    Optically active ditopic halogen bond donors bearing two 4-iodotetrafluorophenyl groups were obtained by reaction of chiral diols with iodopentafluorobenzene. Co-crystallization of these donors with anti-4,4′-azopyridine afforded binary complexes containing infinite chains of the alternating component molecules connected by halogen bonds. The solid state CD measurements confirmed that complexation induces optical activity of the azo chromophore due to the twisting of the aryl-N=N system or external chiral perturbation exerted by host molecules.

  • Indywidualna wystawa "Lubię wracać tam, gdzie byłem", Galeria Żak
    • Patryk Różycki
    2019

  • Influence of artificial thermal ageing on polyester-reinforced and polyvinyl chloride coated AF9032 technical fabric
    • Paweł Kłosowski
    • Krzysztof Żerdzicki
    • Krzysztof Woznica
    2019 TEXTILE RESEARCH JOURNAL

    The presented work deals with the thermal ageing evaluation for polyester-reinforced and polyvinyl chloride coated fabrics. The architectural fabric AF9032 was exposed to artificial thermal ageing by subjecting the material samples to temperature levels of 80℃ and 90℃ for up to 12 weeks. The mechanical properties of the aged fabric have been separately described by the identified linear piecewise model (with assumption of the elastic behavior) and by the Bodner–Partom model (with assumption of the viscoplastic behavior). The evolution of the obtained parameter values for various ageing temperatures and over ageing periods have been approximated by linear functions achieving a good convergence. The simplified methodology of Arrhenius has been incorporated for the extrapolation of functions obtained for 90℃ and consequently used for ageing analysis. For the fill direction, the lines describing evolution of the mechanical parameters over ageing time coincide fully with the ultimate tensile strength and elongation at break and are parallel for the Bodner–Partom model parameters (R0,R1,m1,D1,m2,n) when comparing results for 80° and 90℃. For the warp direction, the obtained lines concerning mechanical properties and Bodner–Partom parameters exhibit different tendencies (increasing or decreasing) for both temperatures. Thus, the ageing evaluation according to the Arrhenius law has been confirmed by the obtained results only for the fill direction.

  • Influence of cooling rate and additives on low-temperature properties of asphalt mixtures in the TSRST
    • Marek Pszczoła
    • Cezary Szydłowski
    • Mariusz Jaczewski
    2019 Pełny tekst CONSTRUCTION AND BUILDING MATERIALS

    The paper presents the results and analysis of low-temperature properties of asphalt mixtures according to Thermal Stress Restrained Specimen Test (TSRST) and Indirect Tensile Test methods. Different groups of bitumen were investigated: neat, SBS-modified and highly SBS-modified. Influence of cooling rates (1 C/h, 3 C/h, 5 C/h and 10 C/h) and additives (aramid fibres and crumb rubber) was identified as well. Moreover, for each factor stiffness moduli were back-calculated from the TSRST results and analysed. The greatest impact on the TSRST results had type of bitumen, followed by the cooling rate and additives. Application of longer fibres improved low-temperature properties of the asphalt mixtures.

  • Influence of Different Biofuels on the Efficiency of Gas Turbine Cycles for Prosumer and Distributed Energy Power Plants
    • Dariusz Mikielewicz
    • Krzysztof Kosowski
    • Karol Tucki
    • Marian Piwowarski
    • Robert Stępień
    • Olga Orynycz
    • Wojciech Włodarski
    2019 Pełny tekst ENERGIES

    The efficiency of a gas turbine can be affected by the use of different biofuels usually with a relatively Lower Heating Value (LHV). The paper evaluates the impact of calorific value of fuel on turbine performance and analyzes the possibilities of optimizing turbine construction from the point of view of maximum efficiency for a particular fuel. The several variants of design of small power microturbines dedicated to various biofuels are analyzed. The calculations were carried out for: gas from biomass gasification (LHV = 4.4 MJ/kg), biogas (LHV = 17.5 MJ/kg) and methane (LHV = 50 MJ/kg). It is demonstrated that analyzed solution enables construction of several kW power microturbines that might be used on a local scale. Careful design of such devices allows for achieving high efficiency with appropriate choice of the turbine construction for specific fuel locally available. Such individually created generation systems might be applied in distributed generation systems assuring environmental profits.