Repozytorium publikacji - Politechnika Gdańska

Ustawienia strony

english
Repozytorium publikacji
Politechniki Gdańskiej

Pokaż publikacje z roku

Ostatnie pozycje

  • SiC-Based Power Electronic Traction Transformer (PETT) for 3 kV DC Rail Traction
    • Marek Adamowicz
    • Janusz Szewczyk
    2020 Pełny tekst 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 Pełny tekst 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.

  • Signature Partitioning Using Selected Population-Based Algorithms
    • Marcin Zalasiński
    • Krzysztof Cpałka
    • Tacjana Niksa-Rynkiewicz
    • Yoichi Hayashi
    2020

    Dynamic signature is a biometric attribute which is commonly used for identity verification. Artificial intelligence methods, especially population-based algorithms (PBAs), can be very useful in the dynamic signature verification process. They are able to, among others, support selection of the most characteristic descriptors of the signature or perform signature partitioning. In this paper, we focus on creating the most characteristic signature partitions using different PBAs and comparing their effectiveness. The simulations whose results are presented in this paper were performed using the BioSecure DS2 database distributed by the BioSecure Association.

  • Silica Gel Impregnated by Deep Eutectic Solvents for Adsorptive Removal of BTEX from Gas Streams
    • Patrycja Makoś
    • Edyta Słupek
    • Aleksandra Małachowska
    2020 Pełny tekst Materials

    The paper presents the preparation of new adsorbents based on silica gel (SiO2) impregnated with deep eutectic solvents (DESs) to increase benzene, toluene, ethylbenzene, and p-xylene (BTEX) adsorption efficiency from gas streams. The DESs were synthesized by means of choline chloride, tetrapropylammonium bromide, levulinic acid, lactic acid, and phenol. The physico-chemical properties of new sorbent materials, including surface morphology and structures, as well as porosity, were studied by means of thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller analysis. The effect of DESs type, flow rate, and initial concentration of BTEX were also investigated followed by regeneration and reusability of adsorbents. The results indicate that SiO2 impregnated with tetrapropylammonium bromide and lactic acid in a 1:2 molar ratio have great potential for the removal of BTEX from gas streams. Its adsorption capacity was higher than the pure SiO2 and other developed SiO2-DES adsorbents. This result can be explained by the specific interaction between DESs and BTEX, i.e., hydrogen bonds interaction.

  • Silicon Oxycarbide-Graphite Electrodes for High-Power Energy Storage Devices
    • Dominik Knozowski
    • Magdalena Graczyk-Zajac
    • Grzegorz Trykowski
    • Monika Wilamowska-Zawłocka
    2020 Pełny tekst Materials

    Herein we present a study on polymer-derived silicon oxycarbide (SiOC)/graphite composites for a potential application as an electrode in high power energy storage devices, such as Lithium-Ion Capacitor (LIC). The composites were processed using high power ultrasound-assisted sol-gel synthesis followed by pyrolysis. The intensive sonication enhances gelation and drying process, improving the homogenous distribution of the graphitic flakes in the preceramic blends. The physicochemical investigation of SiOC/graphite composites using X-ray diffraction, 29Si solid state NMR and Raman spectroscopy indicated no reaction occurring between the components. The electrochemical measurements revealed enhanced capacity (by up to 63%) at high current rates (1.86 A g−1) recorded for SiOC/graphite composite compared to the pure components. Moreover, the addition of graphite to the SiOC matrix decreased the value of delithiation potential, which is a desirable feature for anodes in LIC.

  • Simplified Approach for Broadband RF Testing of Low Loss Magneto-Dielectric Samples
    • Nilesh K. Tiwari
    • Surya P. Singh
    • Abhishek Jha
    • M. Jaleel Akhtar
    2020 IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

    In this paper, an attractive measurement techniqueis proposed to retrieve the broadband permittivity and permeabil-ity of the magneto-dielectric materials. The proposed techniqueis quite novel which mitigates the major problems associatedwith the conventional broadband RF material characterizationtechniques such as numerical instability and phase uncertaintywhen the length of the sample exceeds the integer multipleof half-wavelength. The approach adopted in this paper isquite unique as it alleviates the error normally caused by thesensitive phase measurement, since it only employs the relativeamplitude of the scattering parameters, thus minimizing themeasurement uncertainty. The proposed methodology here isbased on the development of a unified scheme for the retrieval ofdielectric and magnetic properties of magneto-dielectric samples,which is first tested for a number of reference samples usingthe numerically generated scattering coefficient data. Finally,the proposed technique is experimentally validated by measuringa number of standard samples over a broad microwave frequencyrange with the help of the coaxial line and the network analyzer.The dielectric and magnetic properties of samples retrieved usingthe proposed approach is always found to be in good agreementwith their actual values available in the literature

  • Simulating Power Generation from Photovoltaics in the Polish Power System Based on Ground Meteorological Measurements—First Tests Based on Transmission System Operator Data
    • Jakub Jurasz
    • Marcin Wdowikowski
    • Mariusz Figurski
    2020 Pełny tekst ENERGIES

    The Polish power system is undergoing a slow process of transformation from coal to one that is renewables dominated. Although coal will remain a fundamental fuel in the coming years, the recent upsurge in installed capacity of photovoltaic (PV) systems should draw significant attention. Owning to the fact that the Polish Transmission System Operator recently published the PV hourly generation time series in this article, we aim to explore how well those can be modeled based on the meteorological measurements provided by the Institute of Meteorology and Water Management. The hourly time series of PV generation on a country level and irradiation, wind speed, and temperature measurements from 23 meteorological stations covering one month are used as inputs to create an artificial neural network. The analysis indicates that available measurements combined with artificial neural networks can simulate PV generation on a national level with a mean percentage error of 3.2%.

  • Simulation of Signal Propagation Along Fractional-Order Transmission Lines
    • Tomasz Stefański
    • Damian Trofimowicz
    • Jacek Gulgowski
    2020

    In this paper, the simulation method of signal propagation along fractional-order (FO) transmission lines is presented. Initially, fractional calculus and the model of FO transmission line are introduced. Then, the algorithm allowing for simulation of the nonmonochromatic wave propagation along FO transmission lines is presented. It employs computations in the frequency domain, i.e., an analytical excitation is transformed to the frequency domain, multiplications with phase factors are executed, and finally the result is transformed back to the time domain. This algorithm involves elementary functions only and the fast Fourier transformation, hence, computations are numerically efficient and accurate. However, applicability of the method is limited by the sampling theorem. Numerical results are presented allowing for the evaluation of the method.

  • Simulation of Wave Propagation in Media Described by Fractional-Order Models
    • Tomasz Stefanski
    • Jacek Gulgowski
    2020 Pełny tekst

    In this paper, algorithms for simulation of the wave propagation in electromagnetic media described by fractional-order (FO) models (FOMs) are presented. Initially, fractional calculus and FO Maxwell's equations are introduced. The problem of the wave propagation is formulated for media described by FOMs. Then, algorithms for simulation of the non-monochromatic wave propagation are presented which employ computations in the time domain (TD) and the frequency domain (FD). In the TD algorithm, the electromagnetic field is computed as a convolution of an excitation with Green's function formulated based on an improper integral and the Mittag-Leffler function. On the other hand, the FD algorithm transforms an analytic excitation to FD, executes multiplications with phase factors, and finally transfers back result to TD. This algorithm involves elementary functions only, hence, computations are significantly faster and accurate with its use. However, applicability of the FD algorithm is limited by the sampling theorem. Numerical results and computation times obtained with the use of both algorithms are presented and discussed in detail.

  • Simulation-Driven Antenna Modeling by Means of Response Features and Confined Domains of Reduced Dimensionality
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2020 Pełny tekst IEEE Access

    In recent years, the employment of full-wave electromagnetic (EM) simulation tools has become imperative in the antenna design mainly for reliability reasons. While the CPU cost of a single simulation is rarely an issue, the computational overhead associated with EM-driven tasks that require massive EM analyses may become a serious bottleneck. A widely used approach to lessen this cost is the employment of surrogate models, especially data-driven ones: versatile and easily accessible. Yet, one of the unresolved issues remains the curse of dimensionality. Standard modeling techniques are merely capable of rendering surrogates for low-dimensional cases within narrow parameter ranges. In pursuit to overcome these limitations, a novel technique has been recently proposed, where the overall modeling process is carried out within a confined domain, set up based on performance specifications and spectral analysis of an auxiliary set of reference designs. This work offers a further development of the aforementioned method. Instead of tackling the entire antenna responses, only the selected characteristic points (relevant to the figures of interest considered in the antenna design process) are handled. This allows for achieving excellent model accuracy at a low computational cost. The proposed approach can be an attractive modeling alternative for systems with well-structured characteristics.

  • Simulations of hydro-fracking in rock mass at meso-scale using fully coupled DEM/CFD approach
    • Marek Krzaczek
    • Michał Nitka
    • Jan Kozicki
    • Andrzej Tejchman-Konarzewski
    2020 Pełny tekst Acta Geotechnica

    The paper deals with two-dimensional (2D) numerical modelling of hydro-fracking (hydraulic fracturing) in rocks at the meso-scale. A numerical model was developed to characterize the properties of fluid-driven fractures in rocks by combining the discrete element method (DEM) with computational fluid dynamics (CFD). The mechanical behaviour of the rock matrix was simulated with DEM and the behaviour of the fracturing fluid flow in newly developed and pre- existing fractures with CFD. The changes in the void geometry in the rock matrix were taken into account. The initial 2D hydro-fracking simulation tests were carried out for a rock segment under biaxial compression with one injection slot in order to validate the numerical model. The qualitative effect of several parameters on the propagation of a hydraulic fracture was studied: initial porosity of the rock matrix, dynamic viscosity of the fracking fluid, rock strength and pre- existing fracture. The characteristic features of a fractured rock mass due to a high-pressure injection of fluid were realistically modelled by the proposed coupled approach.

  • Simultaneous optical and electrochemical label-free biosensing with ITO-coated lossy-mode resonance sensor
    • Mateusz Śmietana
    • Marcin Koba
    • Petr Sezemsky
    • Katarzyna Szot-Karpińska
    • Dariusz Burnat
    • Vitezslav Stranak
    • Joanna Niedziółka-Jönsson
    • Robert Bogdanowicz
    2020 Pełny tekst BIOSENSORS & BIOELECTRONICS

    In this work we discuss a new label-free biosensing device based on indium tin oxide (ITO) overlaid section of a multimode optical fiber fused silica core. The sensor has been used to optical measurements also simultaneously interrogated electrochemically (EC). Due to optimized thickness and optical properties of ITO film, a lossy-mode resonance (LMR) could be observed in the optical domain, where electrical properties of the film allowed for application of the sensor as a working electrode in an EC setup. It has been confirmed that the LMR response depends on optical properties of the external medium, as well as potential applied to the electrode during cyclic voltammetry. After the ITO surface functionalization with amine groups and covalently attached biotin, the device has been applied for label-free biosensing of avidin in both the domains simultaneously. On the example of biotin-avidin detection system it was demonstrated that when avidin concentration increases a decrease in current and increase in LMR wavelength shift were recorded in EC and optical domain, respectively. Both optical and EC responses follow the protein interaction process, and thus can be used as cross-verification of the readouts. Moreover, an extended information has been achieved comparing to solely EC interrogation, i.e., the grafting process of biotin and avidin was directly monitored optically displaying individual steps of an incubation procedure.

  • Simultaneous Removal of Hexane and Ethanol from Air in a Biotrickling Filter—Process Performance and Monitoring Using Electronic Nose
    • Piotr Rybarczyk
    • Bartosz Szulczyński
    • Jacek Gębicki
    2020 Pełny tekst Sustainability

    Biofiltration is a well-accepted method for the removal of malodorous compounds from air streams. Interestingly, the mechanisms underlying this process are not fully understood. The aim of this paper was to investigate the simultaneous removal of hydrophobic hexane with hydrophilic ethanol, resulting in the enhanced removal of hexane in the presence of ethanol. Investigations were performed in a peat-perlite packed biotrickling filter and the process performance was monitored using both gas chromatography and electronic nose techniques. The results indicate that the length as well as the eciency of biofiltration during the start-up period depend on the feed composition, with higher eciency obtained when hexane and ethanol were fed together from the process initiation. The experiments in the steady-state period present the biofilter performance when dierent ratios of hydrophilic to hydrophobic compounds were fed to the biofilter. The obtained results show the synergistic eects of the addition of a hydrophilic compound on the removal eciency of hydrophobic hexane. The influence of the ratio of hydrophilic to hydrophobic compounds is discussed in terms of enhancing the mass transfer phenomena for hydrophobic volatile organic compounds.

  • Simultaneous voltammetric determination of Cd2+, Pb2+, and Cu2+ ions captured by Fe3O4@SiO2 core-shell nanostructures of various outer amino chain length
    • Amanda Kulpa
    • Jacek Ryl
    • Grzegorz Schroeder
    • Adrian Koterwa
    • Jacek Sein Anand
    • Tadeusz Ossowski
    • Paweł Niedziałkowski
    2020 Pełny tekst JOURNAL OF MOLECULAR LIQUIDS

    In the present study, we examined a novel functionalised magnetic nanoparticles Fe3O4@SiO2-Nn as a nano adsorbent for binding of Cd2+, Pb2+, Cu2+ ions in an aqueous solution. First, we obtained the nanoparticles functionalised with various carbon chains containing different number of amino groups: (3-amino)propyltriethoxysilane (Fe3O4@SiO2-N1), N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (Fe3O4@SiO2-N2) and N1-(3-trimethoxysilylpropyl)diethylenetriamine (Fe3O4@SiO2-N3). In the next step, we conducted their characterisation using SEM, TEM, FT-IR, and XPS methods. The detection of Cd2+, Pb2+, Cu2+ metal ions was performed under optimised experimental conditions using DPASV and HDME techniques. Using these methods we conducted the Cd2+, Pb2+, Cu2+ binding comparison in 4.5 μM concentration with 4 mg of Fe3O4@SiO2-Nn. Obtained results show that the adsorption rate of each ion differs due to the nanoparticles modification. The highest Pb2+ binding capacity was achieved using Fe3O4@SiO2-N1 and Fe3O4@SiO2-N2. The smallest binding capacity was observed for Cd2+ ions by Fe3O4@SiO2-N2 and Fe3O4@SiO2-N1. The Cd2+ biding was not observed for both Fe3O4@SiO2-N2 and Fe3O4@SiO2-N3 nanoparticles. Additionally, Pb2+ was not bound by Fe3O4@SiO2-N3. The research results show that the Fe3O4@SiO2-N3 nanoparticles bind copper ions with high selectivity. For the first time we performed the adsorption-desorption experiments using DPASV to prove the Cu2+ binding activity of Fe3O4@SiO2-N3 nanoparticles. Obtained results indicate that examined nanoparticles show strong binding capability. Additionally, we obtained 99.9% recovery of Cu2+ ions.

  • Single and Three -Phase PWM AC/AC Converters as Semiconductor Transformers
    • Ryszard Strzelecki
    • Natalia Strzelecka
    2020 Pełny tekst

    AC voltage transformation circuits contain pure or reactance PWM AC/AC converters. These circuits can be treated as AC/AC semiconductor transformers. This paper reviews single-phase and three-phase topologies: both non-isolated and isolated, single as well as two quadrant structure. Additionally, this paper present selected examples of their applications.

  • Single crystal growth and physical properties of MCo2Al9 (M= Sr, Ba)
    • Zuzanna Ryżyńska
    • Tomasz Klimczuk
    • Michał Winiarski
    2020 Pełny tekst JOURNAL OF SOLID STATE CHEMISTRY

    Single crystals of SrCo2Al and BaCo2Al9 were grown using a self-flux method. A LeBail analysis of the powder X-ray diffraction patterns show that both compounds crystallize in a hexagonal (P6/mmm) crystal structure with lattice parameters: a ​= ​7.8995(1) Å, c ​= ​3.9159(1) Å for SrCo2Al9, and a ​= ​7.9162(2) Å, c ​= ​3.9702(1) Å for BaCo2Al9 aluminide. The low temperature analysis of the heat capacity measurements give a Sommerfeld coefficient γ ​= ​4.99(6) mJ mol−1 K−2 for SrCo2Al9 and almost twice larger γ ​= ​7.94(9) mJ mol−1 K−2 for BaCo2Al9. Resistivity measurements show metallic-like behavior, with reasonably large residual resistivity ratio RRR ​= ​6 and 10 for SrCo2Al9 and BaCo2Al9, respectively. Neither heat capacity nor resistivity measurements reveal any phase transition down to 1.8 ​K.

  • Single-step grown boron doped nanocrystalline diamond-carbon nanograss hybrid as an efficient supercapacitor electrode
    • Debosmita Banerjee
    • Kamatchi J Sankaran
    • Sujit Deshmukh
    • Mateusz Ficek
    • Chien-Jui Yeh
    • Jacek Ryl
    • I-Nan Lin
    • Robert Bogdanowicz
    • Aloke Kanjilal
    • Ken Haenen
    • Susanta Sinha Roy
    2020 NANOSCALE

    Direct synthesis of nano-structured carbon hybrid consisting of vertically aligned carbon nanograss on top of boron-doped nanocrystalline diamond is demonstrated and the carbon hybrid is further applied as an electrode material for the fabrication of supercapacitor. The hybrid film combines the dual advantages of sp2 (carbon nanograss) and sp3 (nanocrystalline diamond) bonded carbon, possessing not only the excellent electrical characteristics of sp2 carbon but also exceptional electrochemical stability of sp3 carbon. As a result, the specific capacitance of the as-prepared hybrid material reaches upto 0.4 F cm-2, one of the highest reported in diamond-based supercapacitors. The entire electrochemical results exhibit enhanced electron transfer efficiency with remarkable stability of 95% of capacitance retention even after 10000 cycles.

  • Skład chemiczny wód podziemnych dopływających z Pobrzeża Kaszubskiego do Zatoki Puckiej
    • Dawid Potrykus
    • Małgorzata Pruszkowska-Caceres
    • Beata Jaworska-Szulc
    • Anna Gumuła-Kawęcka
    • Adam Szymkiewicz
    2020 Pełny tekst Przegląd Geologiczny

    Zatoka Pucka jest płytkim akwenem morskim szczególnie wrażliwym na dopływ biogenów z otaczających obszarów lądowych. Postępujący problem eutrofizacji wód zatoki wymaga podjęcia działań badawczych i naprawczych, w tym również odpowiedzi na pytanie czy i w jaki sposób spływające do zatoki wody podziemne wpływają na zjawisko eutrofizacji. Celem przeprowadzonych badań, przedstawionych w niniejszym artykule, było określenie składu chemicznego wód podziemnych wraz z analizą ich jakości na wysoczyznowym obszarze Pobrzeża Kaszubskiego. Analizując wyniki badań można uznać, iż skład chemiczny wydzielonych poziomów wodonośnych jest zbliżony. Wykazuje jednak zmienność parametrów hydrogeochemicznych w czasie, zmienność wraz ze wzrostem głębokości występowania wód podziemnych oraz mozaikowy rozkład przestrzenny. Zanieczyszczenie wód podziemnych dotyczy przede wszystkim wód poziomu zawieszonego Qz oraz górnego poziomu wodonośnego Q1, i występuje jedynie punktowo. Zatoka Pucka jest obszarem drenażu wód podziemnych poziomów Q1 i Q2. Stwierdzono, że w wodach podziemnych dopływających do zatoki stężenia większości analizowanych parametrów hydrogeochemicznych nie przekraczają norm jakościowych dla I i II klasy (wody bardzo dobrej i dobrej jakości).

  • Skośna kryza segmentowa do pomiaru przepływającego strumienia płynu
    • Andrzej Mrowiec
    • Marcin Heronimczak
    • Anna Golijanek-Jędrzejczyk
    2020

    Przedstawiono prototypową skośną kryzę segmentową, którą cechuje to, że w zwężkowym układzie pomiaru strumienia objętości wykorzystano pochyloną płaszczyznę kryzy segmentowej. Płyn napierając na kryzę spływa po jej powierzchni. Przyjęto kąt napływu α między płaszczyzną kryzy segmentowej a kierunkiem przepływu (osią rurociągu) mniejszy od kąta prostego. Wyniki symulacji numerycznych oraz badań przepływowych przez zwężkowy przepływomierz ze skośną kryzą segmentową, przy jej pochyleniu α = 60° i przewężeniu β = 0,5, przedstawiono w postaci wykresów i map rozkładu ciśnienia statycznego.

  • Skuteczność nowoczesnych algorytmów optymalizacji czerpiących inspirację z procesów naturalnych
    • Zuzanna Klawikowska
    • Bartosz Puchalski
    2020 Pełny tekst Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    Ze względu na nieistnienie uniwersalnego algorytmu optymalizacji rozwiązującego wszystkie problemy naukowo techniczne opracowywanie nowych i wydajniejszych obliczeniowo algorytmów optymalizacyjnych wciąż jest popularnym zadaniem. Przeglądając literaturę z dziedziny optymalizacji można zauważyć trend tworzenia „wymyślnych” algorytmów opartych na procesach naturalnych. W artykule sprawdzono skuteczność nowo powstałych algorytmów meta-heurystycznych zainspirowanych życiem owadów i zwierząt – czarnych wdów (algorytm BWO) oraz szarego wilka (algorytm GWO). Skuteczność działania wybranych algorytmów porównano z klasycznym algorytmem quasi Newtonowskim BFGS oraz strategią ewolucyjną CMA-ES, które charakteryzują się solidnym uwarunkowaniem matematycznym. W celach porównawczych wykorzystano 3 wybrane funkcje testowe. W ramach badań sprawdzono również wpływ liczby zmiennych decyzyjnych na czas uzyskiwania rozwiązania.

  • Slurry Surfacing Mixes on the Basis of Bitumen Modified with Phenol-Cresol-Formaldehyde Resin
    • Yuriy Demchuk
    • Volodymyr Gunka
    • Serhiy Pyshyev
    • Iurii Sidun
    • Yurii Hrynchuk
    • Justyna Kucińska-Lipka
    • Michael Bratychak
    2020 Pełny tekst Chemistry & Chemical Technology

    Slow-breaking monophase cationic bitumen emulsions have been produced on the basis of bitumen modified with phenol-cresol-formaldehyde resin (PhCR-F). Bitumen emulsions were used as a binder for thin-layer coatings with slurry surfacing mixes (SSM). Physical and technical parameters of modified and unmodified emulsions were determined and analyzed. The optimal compositions of SSM were selected according to the breaking criterion. The values of SSM wet track abrasion were determined. It was found that the addition of PhCR-F allows to improve the adhesion properties of the thin-layer coatings.

  • Small Vessel with Inboard Engine Retrofitting Concepts; Real Boat Tests, Laboratory Hybrid Drive Tests and Theoretical Studies
    • Wojciech Leśniewski
    • Daniel Piątek
    • Konrad Marszałkowski
    • Wojciech Litwin
    2020 Pełny tekst ENERGIES

    The development of modern technologies and their increasing availability, as well as the falling costs of highly ecient propulsion systems and power sources, have resulted in electric or hybrid propulsions systems’ growing popularity for use on watercraft. Presented in the paper are design and lab tests of a prototype parallel hybrid propulsion system. It describes a concept of retrofitting a conventionally powered nine meter-long vessel with the system, and includes results of power and eciency measurements, as well as calculations of the vessel’s operating range under the propulsion of its electric motor. The concept of adding of a solar panels array was studied.

  • Smart acoustic band structures
    • Wiktor Waszkowiak
    • Arkadiusz Żak
    • Magdalena Palacz
    • Marek Krawczuk
    2020

    Smart acoustic band structures exhibit very interesting and non-standard physical properties due to the periodic nature of their certain characteristic on different scale levels. They manifest mostly in their frequency spectra as socalled frequency band-gaps or stop-bands, what has a great impact on the behaviour of these structures in relation to the propagation of vibro-acoustic signals that can be transmitted through the structures in some precisely defined frequency bands. Properties of acoustic band structures are directly linked to their geometry on the level of the unit cell, which parameters determine structural dynamics of such structures on the macroscopic scale. Here the piezoelectric transducers play a significant role. The combined exploitation of active properties of acoustic band structures equipped with active piezoelectric elements, in order to filter or damp transmitted vibro-acoustic signals, allows for very effective their applications. In their paper, the authors present certain results of certain computer simulations by the time-domain spectral finite element method, related to 1-D smart active and passive acoustic band structures supplemented with experimental measurements.

  • Smart Decisional DNA Technology to Enhance Industry 4.0 Environment in Conjunction with Conventional Manufacturing
    • Imran Shafiq
    • Cesar Sanin
    • Edward Szczerbicki
    2020

    Knowledge-based support has become an indispensable part not only to the traditional manufacturing set-ups but also to the new fast-emerging Industry 4.0 scenario. In this regard, successful research has been performed and extensively reported to develop Decisional DNA based knowledge representation models of engineering object and engineering process called Virtual engineering object (VEO), Virtual engineering process (VEP) and Virtual engineering factory (VEF). These models are the virtual representation of manufacturing resources, and with the help of IoT, are capable of capturing the past experience and formal decisions. In this chapter, a complete virtual manufacturing environment is summarized. Furthermore, the scope of this work is explained in the Cyber-Physical Systems (CPS) based Industry 4.0 framework. Four case studies are presented to validate the practical implementation of the proposed concept. In the first case the idea of VEO-VEP-VEF is applied to design an intelligent factory framework to achieve contextual information through real-time visualization. In the second study, the smart tool performance analysis is presented in which data of key tool parameters like tool life, surface integrity, tool forces, and chip formation can be sensed in real-time; also predictions can be made according to the specific requirements. In the third case study, the technique of Decisional DNA (DDNA) is applied to FMS to develop a generic model to achieve effective scheduling and manufacturing flexibility. In the last study, the framework to manage the storage, analysis, and processing of data, information, and knowledge of a typical CIM is presented. The benefits of this approach are manifold as it creates manufacturing DNA of a factory, felicitates in effective decision making, increases the rate of production, reduces errors and production waste, and streamlines manufacturing sub-systems. Moreover, and can be instrumental in designing Industry 4.0.

  • Smart Embedded Systems with Decisional DNA Knowledge Representation
    • Zhang Haoxi
    • Fei Li
    • Cesar Sanin
    • Edward Szczerbicki
    2020

    Embedded systems have been in use since the 1970s. For most of their history embedded systems were seen simply as small computers designed to accomplish one or a few dedicated functions; and they were usually working under limited resources i.e. limited computing power, limited memories, and limited energy sources. As such, embedded systems have not drawn much attention from researchers, especially from those in the artificial intelligence area. Thanks to the efforts of scientists over recent years, great progress has been made in both computer hardware and software, which enables us to have much more powerful computers in very small sizes and with many more functions. Consequently, new expectations and needs for embedded systems have increased considerably. Today, smart embedded systems are expected, which are supposed to have capability to learn from past task executions and evolve their performance based on learnt knowledge, and assist users to make good decisions more efficiently. Therefore, how to make embedded systems smart is becoming one of the researchers’ new challenges. In this chapter, we introduce the Experience-Oriented Smart Embedded Systems (EOSES) that is proposed as a new technological scheme providing embedded systems with capabilities for experiential knowledge capturing, storage, reuse, evolving, and sharing. In this scheme, knowledge is represented as the Set of Experience Knowledge Structure (SOEKS or shortly SOE) and organized as Decisional DNA. The scheme is mainly based on conceptual principles from embedded systems and knowledge management. The objective behind this research is to offer large-scale support for intelligent, autonomous, and coordinated knowledge management on various embedded systems. Several conceptual elements of this research have been implemented in testing prototypes, and the experimental results show that the EOSES scheme can not only provide active knowledge management to different embedded systems, it can also enable various systems to learn from their daily operations in many different fields to acquire valuable knowledge, assist decision making, reduce human workers’ workload, and improve the system’s performance. As a result, the EOSES has great potential for meeting today’s demands for embedded systems, and providing a universe knowledge management scheme for mass autonomous mechanisms.

  • Smart Innovation Engineering Using Set of Experience and Decisional DNA
    • Mohammad Waris
    • Cesar Sanin
    • Edward Szczerbicki
    2020

    Knowledge-based Engineering Systems are founded upon integration of knowledge into computer systems and are one of the core requirements for the future Industry 4.0. Since the fourth industrial revolution is passing through the developing phase, implementation of Cyber-Physical Production Systems require more realistic approach. Knowledge Management and Knowledge Engineering plays an important role in manufacturing industries facing global competition. One of the most promising areas where Knowledge Management is studied and applied is product innovation. This chapter presents the idea of Smart Innovation Engineering (SIE) System based on Set of Experience and Decisional DNA that facilitates the process of product innovation. It collects the experiential knowledge from the formal decisional event from the group of similar products having some common functions and features. The SIE system behaves like a group of experts in its domain as it collects, captures and stores the experiential knowledge and reuses this experiential knowledge as well that ultimately enhances the innovation process. The analysis of basic concepts and implementation method proves that SIE system is an advanced form of Cyber Physical Systems. It is flexible, systematic, fast, and supports customization. It can play a vital role towards Industry 4.0 development.

  • Smart Services for Improving eCommerce
    • Andrzej Sobecki
    • Julian Szymański
    • Henryk Krawczyk
    • Higinio Mora-Mora
    • David Gil
    2020

    The level of customer support provided by the existing eCom-merce solutions assumes that the person using the functionality of theshop has sufficient knowledge to decide on the purchase transaction. Alow conversion rate indicates that customers are more likely to seekknowledge about the particular product than finalize the transaction.This is facilitated by the continuous development of customers’ digi-tal competencies, resulting in the increasing popularity of web servicesenabling the exchange of information, e.g. through social networks. Cur-rently the user act with eCommerce platform like a source of informa-tion. At the same time, he or she usually use more than one source ofinformation e.g., web portals, social networks, etc. The existing onlineshops seem unsuited to these trends because they remain simple tradingplatforms without integration with external web services and sources ofknowledge. New categories of smart services are suggested, enabling thenewly implemented eCommerce network platform to enhance the offeredknowledge and reduce the abandonment of the platform by the user. Ourempirical studies show an increase in the conversion rate in the case ofshops which increased the level of customer support using the proposedmodel of integration.

  • SMART SHOP SERVICES FOR BUILDING CUSTOMER-ORIENTED SCENARIOS
    • Henryk Krawczyk
    • Andrzej Sobecki
    2020 Pełny tekst TASK Quarterly

    The shops of today mostly support the customer by offering him or her products based on basic relationships between products viewed or ordered by users with similar tastes. This common approach may fail in many cases especially when the user does not have sufficient knowledge about the market, or when he or she wants to build a set of products in more than one shop. New categories of smart shop services are proposed in order to execute such customer-oriented scenarios where recommended products do meet mutual dependencies with products previously ordered by the customer. An attempt is made to collect additional information about the behavior of users (from past and current contexts) and represent it in a targeted graph called the customer-oriented scenario. Four types of such scenarios are distinguished depending on how many shops have been visited by the user before buying the expected products and how many products the user wants to buy. Moreover, the proposed scenario model provides the possibility of showing which services had been used by the user before the selection was made. Customer-oriented scenarios may be created post factum based on event data logs or before the user will use the shop, which means that it can be arranged which information, knowledge sources (internal or external), products or categories should be suggested in some context of the user’s decision. The possibility of leveraging additional smart services into a traditional trading platform may help users, especially when they want to implement a complex scenario and order many products with mutual dependencies or in a situation when the user wants to understand the market before buying something. Using internal and external services allows creating a network for distributing knowledge focused on the actual customer context in a shop.

  • Smart Virtual Product Development (SVPD): Experience Based Product Development System for Industry 4.0
    • Muhammad Bilal
    • Cesar Sanin
    • Edward Szczerbicki
    2020

    This chapter presents the concept of smart virtual product development (SVPD) system capable of supporting industrial product development. It enhances the decision making process during various activities involved in product development i.e. product design, manufacturing, and inspection planning. This is achieved by using the explicit knowledge of past formal decision events, which are captured, stored, and recalled in the form of set of experiences (SOEs). The basic description and principles of approach are introduced first, and then the prototype version of the system is developed and tested. Working of the design knowledge management module and manufacturing capability analysis and process planning module of the system are demonstrated with the case study, which verifies the feasibility of the proposed approach. The presented system successfully supports smart product design and manufacturing, and it can play a vital role in Industry 4.0.

  • Smart Virtual Product Development (SVPD) System to Support Product Inspection Planning in Industry 4.0
    • Muhammad Ahmed
    • Cesar Sanin
    • Edward Szczerbicki
    2020 Pełny tekst Procedia Computer Science

    This paper presents the idea of supporting product inspection planning process during the early stages of product life cycle for the experts working on product development. Aim of this research is to assist a collaborative product development process by using Smart Virtual Product Development (SVPD) system, which is based on Set of Experience Knowledge Structure (SOEKS) and Decisional DNA (DDNA). The proposed system is developed to support three key aspects of industrial product development i.e. design, manufacturing, and product inspection. Therefore, it comprises of three main modules; design knowledge management (DKM), manufacturing capability and process planning (MCAPP), and product inspection planning (PIP). It collects, stores, and uses experiential knowledge from formal decisional events in the form of set of experience (SOE). This research enlightens the working mechanism of the PIP module, and shows how experiential knowledge related to product inspection can be used during the early stages of product development process. This experiential knowledge is extracted and stored from similar products having some common features and functions. First, the basic description and principles of the approach are introduced, then the prototype version of the system is developed and tested for product inspection planning (PIP) module for the case study, which verifies the feasibility of the proposed approach. The presented system successfully supports smart manufacturing and can play a vital role in Industry 4.0.

  • Social benefits valuation of hosting non-mega sporting events
    • Krystian Zawadzki
    2020 Pełny tekst International Journal of Event and Festival Management

    Purpose In the study, an attempt was made to estimate the social benefits resulting from three non-mega sporting events organized in Ergo Arena located on the border of two cities in Poland. By attributing a value to intangible social benefits, the intangible effect was determined and compared to the expenditure incurred in the construction of Ergo Arena Hall. Design/methodology/approach In order to value social intangible effects of three non-mega sporting events the Contingent Valuation Method was applied. Each time, the Contingent Valuation Method study covered the area of the two cities: Gdańsk and Sopot and was conducted on a sample of 500 people – 250 per city. The mean values of Willingness-to-Pay were used in order to obtain aggregate values of intangible benefits. Finally, the aggregate results were compared to expenditure incurred in connection with the construction of Ergo Arena Hall. Findings It appeared that intangible effects were eagerly valued by the residents of Gdańsk and Sopot. The aggregated value of all three sporting events was estimated at PLN 8.8 million. The obtained results question the equal share of both cities in financing but confirm that under certain circumstances, hosting non-mega sporting events may justify the use of public funds. In the case of the two cities, the reasonable reason for the employment of public means is the size of Gdańsk compared to Sopot. Originality/value The paper fulfils the research gap which arises regarding Willingness-to-Pay in estimating the intangible social effects of non-mega sporting events and considering these effects in the net effect valuation. The findings have implications for policy makers since they show to what extent it may be justified to use public means in order to host non-mega sporting events.

  • Soft Sensor Application in Identification of the Activated Sludge Bulking Considering the Technological and Economical Aspects of Smart Systems Functioning
    • Bartosz Szeląg
    • Jakub Drewnowski
    • Grzegorz Łagód
    • Dariusz Majerek
    • Ewa Dacewicz
    • Francesco Fatone
    2020 Pełny tekst SENSORS

    The paper presented the methodology for the construction of a soft sensor used for activated sludge bulking identification. Devising such solutions fits within the current trends and development of a smart system and infrastructure within smart cities. In order to optimize the selection of the data-mining method depending on the data collected within a wastewater treatment plant (WWTP), a number of methods were considered, including: artificial neural networks, support vector machines, random forests, boosted trees, and logistic regression. The analysis conducted sought the combinations of independent variables for which the devised soft sensor is characterized with high accuracy and at a relatively low cost of determination. With the measurement results pertaining to the quantity and quality of wastewater as well as the temperature in the activated sludge chambers, a good fit can be achieved with the boosted trees method. In order to simplify the selection of an optimal method for the identification of activated sludge bulking depending on the model requirements and the data collected within the WWTP, an original system of weight estimation was proposed, enabling a reduction in the number of independent variables in a model— quantity and quality of wastewater, operational parameters, and the cost of conducting measurements.

  • Soft-mode enhanced type-I superconductivity in LiPd2Ge
    • Karolina Górnicka
    • Gabriel Kuderowicz
    • Elizabeth M. Carnicom
    • Kamil Kutorasiński
    • Bartlomiej Wiendlocha
    • Robert J. Cava
    • Tomasz Klimczuk
    2020 Pełny tekst PHYSICAL REVIEW B

    The synthesis, crystal structure, and physical properties (magnetization, resistivity, heat capacity) in combination with theoretical calculations of the electronic structure and phonon properties are reported for intermetallic compounds LiPd2X (X = Si, Ge, and Sn). LeBail refinement of powder x-ray diffraction data confirms that all compounds belong to the Heusler family (space group Fm-3m, No. 225). The lattice parameter increases with atomic size of X, and its value varies from a = 5.9059(4) Å for LiPd2Si and a = 6.0082(3) Å for LiPd2Ge, to a = 6.2644(1) Å for LiPd2Sn. The first compound, LiPd2Si, has apparently not been previously reported. All measured quantities demonstrate that LiPd2Ge exhibits superconductivity below Tc = 1.96 K and the normal and superconducting-state data indicate that it is a weak-strength type-I superconductor (C/γ Tc = 1.38) with electron-phonon coupling constant λe−p = (0.53 − 0.56). LiPd2Si and LiPd2Sn are not superconducting above 1.68 K. The experimental observations are supported by theoretical calculations which show that LiPd2Ge has the highest computed λe−p and Tc of the group. A strong softening of the acoustic phonon mode is calculated, and in the case of X = Ge and Sn, imaginary phonon frequencies were computed. The soft mode is most pronounced in the case of LiPd2Ge, which suggests its correlation with superconductivity.

  • Solvent dependency of carbon dioxide Henry's constant in aqueous solutions of choline chloride-ethylene glycol based deep eutectic solvent
    • Ali Reza Harifi-Mood
    • Fereshteh Mohammadpour
    • Grzegorz Boczkaj
    2020 Pełny tekst JOURNAL OF MOLECULAR LIQUIDS

    The Henry's constants of carbon dioxide absorbed in aqueous solutions of ethaline (choline chloride-ethylene glycol) were determined for temperatures ranging from 303.15 to 323.15 K based on solubility measurement at CO2 pressure ranging from 0 to 6 bar (0.6 MPa). These studies revealed that the Henry's constant increased with the increase of temperature. Data indicated the highest capacity of CO2 absorption is obtained for ethaline and the lowest temperature dependency of absorption capacity is reported for aqueous solution of ethaline based deep eutectic solvent (0.3 mol fraction of water). The dependence of Henry's constant on solvent composition and solvent properties was investigated using preferential solvation model and linear free energy relationship method. Results showed that CO2 was preferentially solvated by ethaline in aqueous solution. Furthermore it revealed that solute-solvent interactions related to the scale of hydrogen bond donor ability of the solvent were the main parameter which controls the solubility of CO2 in the studied system. Presented methodology is useful for selection of best absorbent composition for systems of hot off-gases treatment. Interesting and practical results obtained in this work, indicated that precisely selected composition of the deep eutectic solvent based absorbent provide low sensitivity of the treatment performance in respect to the temperature of the treated gas.

  • Solvent Impact on the Diversity of Products in the Reaction of Lithium Diphenylphosphide and a Ti(III) Complex Supported by a tBu2P–P(SiMe3) Ligand
    • Aleksandra Ziółkowska
    • Natalia Szynkiewicz
    • Jerzy Pikies
    • Łukasz Ponikiewski
    2020 Pełny tekst INORGANIC CHEMISTRY

    We present two important trends in the reactivity ofthe titanium complex [MeNacNacTi(Cl){η2-P(SiMe3)-PtBu2}](MeNacNac− = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-iPr2Ph)with nucleophilic reagents RLi (R = Ph2P,tBuO, (Me3Si)2N, andtBu2N) depending on the reaction medium. Reaction in nonpolarsolvent (toluene) leads to three main products: via an autoredoxprocess and nucleophilic substitution at the Ti-atom to afford theTi(IV) complex [MeNacNacTi(R){η2-P-PtBu2}] (1for R = PPh2),via the elimination of Me3SiR to afford Ti(III) complex[MeNacNacTi(Cl){η2-P-PtBu2}]−[Li(12-crown-4)2]+(2), and via2e−reduction process to afford new ionic complex [{ArNC(Me)-CHC(Me)}TiNAr{η1-P(SiMe3)-PtBu2}]−[Li(12-crown-4)2]+(3). Quite differently, the complex [MeNacNacTi(Cl){η2-P(SiMe3)-PtBu2}] reacts with Ph2PLi in THF, unexpectedly yielding two new, four-coordinate Ti(IV) imido complexes4a[{ArNC(Me)CHC(H)(Me)-P(PtBu2)}TiNAr(Cl)]−[Li(12-crown-4)2]+·(toluene)2and4b[{ArNC(CH2)CHC(Me)-P(PtBu2)}TiNAr-(Cl)]−[Li(12-crown-4)2]+·(Et2O). Complex2dissolved in THF converts to4aand4b.1,2,3,4a, and4bwere characterized by X-ray diffraction.1,4a, and4bwere also fully characterized by multinuclear NMR spectroscopy.

  • Some Security Features of Selected IoT Platforms
    • Robert Kałaska
    • Paweł Czarnul
    2020 Pełny tekst TASK Quarterly

    IoT (Internet of Things) is certainly one of the leading current and future trends for processing in the current distributed world. It is changing our life and society. IoT allows new ubiquitous applications and processing, but, on the other hand, it introduces potentially serious security threats. Nowadays researchers in IoT areas should, without a doubt, consider and focus on security aspects. This paper is aimed at a high-level review of the existing IoT enabling standalone middleware solutions and frameworks in terms of potential application areas, architecture and components, communication APIs as well as support for key security features including access control, support against attacks on service, device authorization and data filtering. On the one hand, it allows the developer to choose the middleware best matching their needs. On the other hand, it can serve as a starting point for further research on middleware security features based on the provid ed security related open areas and challenges.

  • Sophistication assessment of existing FEM models of orbital blowout trauma: Is models valuation justified?
    • Marcin Zmuda Trzebiatowski
    • Andrzej Skorek
    2020 Journal of Stomatology Oral and Maxillofacial Surgery

    After a thorough study of the work entitled “Development and validation of an optimized finite element model of the human orbit”, some doubts aroused concerning the sophistication assessment of the existing finite element method (FEM) models of orbital blow-out. Although the work was unquestionably innovative, and the results were not only fascinating but also invaluable, the authors stated that their model was the most sophisticated one ever developed to their best knowledge. Hence, the purpose of this letter is to consider whether and upon what circumstances FEM models valuation may be justified.

  • Spatial and vertical distribution analysis of heavy metals in urban retention tanks sediments: a case study of Strzyza Stream
    • Nicole Nawrot
    • Ewa Wojciechowska
    • Karolina Matej-Łukowicz
    • Jolanta Walkusz-miotk
    • Ksenia Pazdro
    2020 Pełny tekst ENVIRONMENTAL GEOCHEMISTRY AND HEALTH

    Concentrations of seven heavy metals (HMs): Zn, Cu, Pb, Cd, Ni, Cr, and Fe in core samples of bottom sediments from four retention tanks (RTs) located along the Strzyza Stream in northern Poland (Gdansk) were measured to obtain a general view of sediment quality. The recognition of contamination and potential environmental impacts is the main aim of this paper. A total of 96 sediment samples were collected from eight sampling sites at depths of 0–2 cm, 8–10 cm, 16–18 cm, 24–26 cm. Concentrations of Cu, Zn, Pb, Fe, Ni, and Cr were measured with AAS while Cd concentration was measured with ICP-MS. Granulometric analyses with normalized sieve apertures were carried out. Geochemical indices: enrichment factor, anthropogenic factor, and modified degree of contamination (mCd) were used to assess the contamination level. Concentrations of HMs in sediments changed in the range: Cu (3.24–119 mg/kg d.w.), Zn (12.5–584 mg/kg d.w.), Pb (4.91–309 mg/kg d.w.), Cd (0.003–0.716 mg/kg d.w.), Ni (1.57–25.8 mg/kg d.w.), Cr (2.45–74.5 mg/kg d.w.), and Fe (3993–63817 mg/kg d.w.). The sequential extraction verified the bonding of HMs with non-mobile fractions. Geochemical indices showed widespread pollution by Cu, Pb, Cd, and Zn. Cluster and factor analysis distinguished three related subgroups of HMs: Pb, Ni–Cr, and Fe–Cd–Cu–Zn, suggesting possible common source of each subgroup. Strongly contaminated sediments were distinguished in sediment cores in two middle stream RTs characterized by intense urbanization in their direct catchments.

  • Spatial Differences in the Chemical Composition of Surface Water in the Hornsund Fjord Area: A Statistical Analysis with A Focus on Local Pollution Sources
    • Krystyna Kozioł
    • Ruman Marek
    • Filip Pawlak
    • Stanisław Chmiel
    • Żaneta Polkowska
    2020 Pełny tekst Water

    Surface catchments in Svalbard are sensitive to external pollution, and yet what is frequently considered external contamination may originate from local sources and natural processes. In this work, we analyze the chemical composition of surface waters in the catchments surrounding the Polish Polar Station in Svalbard, Hornsund fjord area. We have pooled unpublished and already published data describing surface water composition in 2010, related to its pH, electrical conductivity (EC), metals and metalloids, total organic carbon (TOC) and selected organic compound concentrations, including persistent organic pollutants (POPs) and surfactants. These data were statistically analyzed for spatial differences, using Kruskal–Wallis ANOVA and principal component analysis (PCA), with distance from the station in the PCA approximating local human activity impact. The geological composition of the substratum was found to be a strong determinant of metal and metalloid concentrations, sufficient to explain significant differences between the studied water bodies, except for the concentration of Cr. The past and present human activity in the area may have contributed also to some of the polycyclic aromatic hydrocarbons (PAHs), although only in the case of naphthalene can such an effect be confirmed by an inverse correlation with distance from the station. Other likely factors contributing to the chemical concentrations in the local waters are marine influence, long-range pollution transport and release from past deposition in the environment.

  • Special Issue: “Non-Destructive Testing of Structures”
    • Magdalena Rucka
    2020 Pełny tekst Materials

    The Special Issue “Non-Destructive Testing of Structures” has been proposed to present recent developments in the field of diagnostics of structural materials and components in civil and mechanical engineering. The papers highlighted in this editorial concern various aspects of non-invasive diagnostics, including such topics as condition assessments of civil and mechanical structures and connections of structural elements, the inspection of cultural heritage monuments, the testing of structural materials, structural health monitoring systems, the integration of non-destructive testing methods, advanced signal processing for the non-destructive testing of structures (NDT), damage detection and damage imaging, as well as modeling and numerical analyses for supporting structural health monitoring (SHM) systems.

  • Special Issue: Recent Advances in Corrosion Science
    • Jacek Ryl
    2020 Pełny tekst Materials

    The dynamic development of the global industry and growing demand for new material technologies generates constantly increasing problems regarding premature material degradation and the requirement to determine corrosion mechanisms and to develop new protection/evaluation approaches. This Special Issue, “Recent Advances in Corrosion Science”, brings together fourteen articles and one review, providing a snapshot of the recent activity and development in this field.

  • Speciation of heavy metals in bottom sediments of drinking water reservoir for Gdansk, Poland – changes over the 14 years
    • Eliza Kulbat
    • Aleksandra Sokołowska
    2020 Desalination and Water Treatment

    There was conducted a comparative study of the concentrations of heavy metals (Zn, Cu, Pb, and Cd) in the surface layer of sediments collected in two investigation periods: 1999–2000 and 2013. Theresults demonstrated that the degree of metals pollution decreased over time. The contamina-tion factors (Cf) calculated for Zn, Cu, Pb, and Cd were respectively 3.63, 3.86, 3.23, and 3.25 in the first period of research and 1.35, 3.42, 1.98, and 1.43 in the second one. The metal speciation analysis indicated that Zn was mainly associated with the Fe–Mn oxides fraction and the residual fraction, and Cu – with the residual fraction and the organic fraction in both periods of investigation, while the percentage of geochemical fractions in binding of Pb and Cd changed in time. The share of fractions Fe–Mn oxides/carbonate increased in the case of Pb, and carbonate/exchangeable fractions in the case of Cd. The risk assessment code (RAC) decreased in the following order: Cd>Zn>Pb>Cu and was higher in 2013 - it achieved the very high-risk category in the case of Cd. Thus, despite the decrease of sediment pollution, RAC for Cd increased due to changed geochemical speciation.

  • Spectroscopic Optical Coherence Tomography for Thin Layer and Foil Measurements
    • Aleksandra Kamińska
    • Marcin Strąkowski
    • Jerzy Pluciński
    2020 Pełny tekst SENSORS

    The main goal of this research was to assess if it is possible to evaluate the thickness of thin layers (both thin films on the surface and thin layers below the surface of the tested object) and foils using optical coherence tomography (OCT) for thickness assessment under the resolution of the standard commercially available OCT measurement system. In the proposed solution, light backscattered from the evaluated thin layer has been expressed as a multiple beam interference. Therefore, the OCT system was modeled as a two-beam interferometer (e.g., Michelson), in which one beam propagates from the reference arm and the other comes from a Fabry–Pérot interferometer. As a consequence, the mathematical model consists of the main Michelson interferometer, in which the measuring arm represents the Fabry–Pérot interferometer. The parameters of the layer (or foil) are evaluated by analyzing the minimum value of the interference contrast. The model developed predicts the behavior of the thin layers made from different materials (with different refractive indexes) with different thickness and located at different depths. To verify the correctness of the proposed model, an experiment with a wedge cell has been carried out. The wedge cell was shifted across the scanning beam using a linear translation stage with a micrometer screw under the scanning head. The relationship between the thickness of the gap of the wedge cell and the OCT output signal is presented. For the additional verification of the proposed model, the results of the measurements of the thickness of the thin foil were compared with the theoretical results of the simulations. The film thickness was evaluated based on the calculated positions of the minimum value of interference contrast. A combination of the standard potentialities of OCT with the proposed approach to analyzing the signal produces new metrological possibilities. The method developed allows us to evaluate thickness under the resolution of the system and the location of the layer as well. This produces the possibility of measuring a layer which is covered by another layer. Moreover, it is possible to create a thickness map with high sensitivity to thickness changes. These experiments and simulations are the culmination of preliminary research for evaluating the potential of the proposed measurement method.

  • Spectroscopic studies of Nb-doped tricalcium phosphate glass-ceramics prepared by sol-gel method
    • Wojciech Korzeniewski
    • Agnieszka Witkowska
    • Maciej Manecki
    2020 Synchrotron Radiation in Natural Science

    Calcium-phosphate based glasses and glass-ceramics play a crucial role in the tissue engineering development. Apart from their high biocompatibility and excellent ability to undergo varying degrees of resorbability1, they exhibit relatively high bioactivity and due to that they are commonly used as bone and dental implants. A substantial research effort is devoted to improve calcium-phosphate materials physico-chemical properties by tuning their degree of crystallinity and doping them with metal ions is one of the mostly researched strategies. The results found in the literature show that synthesized CaOP2O5-Nb2O5 compounds exhibit a good biocompatibility, very low cytotoxicity in respect to calciumphosphate doped with other metals and additionally can enhance human osteoblast function2,3. As of today structure of these materials is not thoroughly described. Therefore, the detailed structural investigation by means of spectroscopic studies, i.e. FTIR spectroscopy, Raman spectroscopy, XAFS spectroscopy, XPS and EDX, together with SEM imaging, XRD and BET surface area measurements, was realized to shed light on the relationship between materials structure and the presence of dopant. In this work, we show the results obtained for bioactive glass-ceramics, prepared via simple sol-gel method, with Ca/(P+Nb) molar ratio equal to 1.5 and with relative Nb contents of 0 mol% and 10 mol% of P. XRD patterns analysis shows that samples consist of tricalcium phosphate and hydroxyapatite phase. Raman spectra analysis confirms the incorporation of Nb into the material structure. Moreover, niobium doping leads to an increase in degree of crystallinity and crystallite size of the sample. Stoichiometry of the ceramics is as intended. Additionally, there is a greater proportion of carbonate groups in the doped material than in the undoped one (FTIR, Raman spectroscopy), and all samples exhibit calcium deficiency on the surface (XPS). XAFS analysis shows presence of octahedral coordination of niobium ions, with average oxidation state around +4.5 and XPS analysis indicates that on the sample surface the contribution of Nb+5 ions is greater than Nb+4 ions. Additionally it can be concluded, that Nb accumulates on materials surface.

  • Spinon excitations in the quasi-one-dimensional S=12 chain compound Cs4CuSb2Cl12
    • Thao Tran
    • Chris A. Pocs
    • Yubo Zhang
    • Michał Winiarski
    • Jianwei Sun
    • Minhyea Lee
    • Tyrel McQueen
    2020 Pełny tekst PHYSICAL REVIEW B

    The spin−1/2 Heisenberg antiferromagnetic chain is ideal for realizing one of the simplest gapless quantum spin liquids (QSLs), supporting a many-body ground state whose elementary excitations are fractional fermionic excitations called spinons. Here we report the discovery of such a one-dimensional (1D) QSL in Cs4CuSb2Cl12. Compared to previously reported S=1/2 1D chains, this material possesses a wider temperature range over which the QSL state is stabilized. We identify spinon excitations extending at T>0.8K, with a large T-linear contribution to the specific heat, γ=31.5(2)mJmol−1K−2, which contribute itinerantly to thermal transport up to temperatures as high as T=35K. At T=0.7K, we find a second-order phase transition that is unchanged by a μ0H=5T magnetic field. Cs4CuSb2Cl12 reveals new phenomenology deep in the 1D QSL regime, supporting a gapped QSL phase over a wide temperature range compared to many other experimental realizations.

  • Spirala 2 (wg Ulama) z cyklu No Quick Response
    • Krzysztof Wróblewski
    2020

    Spirala 2 (wg Stanisława Ulama) Obraz odnosi się do modelu matematycznego nazywanego Spiralą Ulama, który polega na okrężnym zapisie w polu kwadratu liczb naturalnych od 1 do nieskończoności. Taki zapis uwidacznia szczególne wzory, które powstają z położenia liczb pierwszych (niepodzielnych). Liczby pierwsze tworzą ciągi mniej lub bardziej regularne w układzie diagonalnym, poziomym i pionowym. W obrazie Spirala 2 wykorzystany został zestaw liczb od 1 do 1600. Położenia liczb pierwszych są malowane czernią i bielą, natomiast położenie pozostałych liczb kolorami podstawowymi i pochodnymi w różnej tonacji. Kolory "wędrują" progresywnie za liczbami po kształcie spirali. Sekwencyjny rytm przerywany jest położeniem liczby pierwszej. W wyniku tego zabiegu samorzutnie powstają grupy różnych form i kolorów, przy czym żadna z nich nie jest dominująca w całości układu. Poszczególne kształty są tylko cząstkami większej całości. W spirali Ulama podobnie jak w ciągu Fibonacciego występuje rodzaj harmonijnej jedności. Krzysztof Wróblewski

  • Społeczna odpowiedzialność biznesu w branży odzieżowej - perspektywa polskiego konsumenta
    • Ewa Marjańska
    • Piotr Grudowski
    • Anna Wendt
    • Mateusz Muchlado
    2020 Problemy Jakości

    Przesunięcie produkcji do krajów dotkniętych ubóstwem towarzyszy podejściu kładącemu nacisk na szybkie odpowiedzialność i tanie udostępnianie trendów modowych konsumentom oraz systemowi wytwarzania opartemu na popycie biznesu, w przemyśle odzieżowym. W artykule zwrócono uwagę na: świadomość, postawy, zachowania etyczne oraz zrównoważony sposób postrzegania jakości produktów „fast fashion” w perspektywie społecznej odpowiedzialności. Na rozwój, podstawie metody CAWI i PAPI przeprowadzono badanie polskich konsumentów deklarujących zachowania przemysł odzieżowy, nabywcze związane z „fast fashion”. Badania wykazały, że działania związane ze społeczną odpowiedzialnością fast fashion biznesu w branży odzieżowej są istotne dla klientów, jednak cena jest najważniejszym czynnikiem przy podejmowaniu decyzji o zakupie. Ocena świadomości konsumentów w zakresie CSR może posłużyć do ukierunkowania przyszłych działań edukacyjnych w tym obszarze, zwłaszcza w dobie przyspieszonej konsumpcji i celów zrównoważonego rozwoju. Wyniki badań mogą też być przesłanką do określenia kierunku działań związanych z CSR dla sprzedawców „fast fashion”.

  • Społeczna odpowiedzialność biznesu w kontekście strategii wybranych spółek posiadających istotne znaczenie dla gospodarki
    • Sebastian Skuza
    • Anna Modzelewska
    • Malwina Popiołek
    • Marta Szeluga-Romańska
    2020

    Przedmiotem badań jest analiza sposobów realizacji strategii społecznej odpowiedzialności biznesu przez przez wybrane spółki z udziałem Skarbu Państwa.

  • Stability analysis of interconnected discrete-time fractional-order LTI state-space systems
    • Łukasz Grzymkowski
    • Damian Trofimowicz
    • Tomasz Stefański
    2020 Pełny tekst International Journal of Applied Mathematics and Computer Science

    In this paper, a stability analysis of interconnected discrete-time fractional-order (FO) linear time-invariant (LTI) state-space systems is presented. A new system is formed by interconnecting given FO systems using cascade, feedback, parallel interconnections. The stability requirement for such a system is that all zeros of a non-polynomial characteristic equation must be within the unit circle on the complex z-plane. The obtained theoretical results lead to a numerical test for stability evaluation of interconnected FO systems. It is based on modern root-finding techniques on the complex plane employing triangulation of the unit circle and Cauchy’s argument principle. The developed numerical test is simple, intuitive and can be applied to a variety of systems. Furthermore, because it evaluates the function related to the characteristic equation on the complex plane, it does not require computation of state-matrix eigenvalues. The obtained numerical results confirm the efficiency of the developed test for the stability analysis of interconnected discrete-time FO LTI state-space systems.