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Gdańsk University of Technology

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  • Soft X-ray Induced Production of Neutral Fragments in High-Rydberg States at the O 1s Ionization Threshold of the Water Molecule
    • Antti Kivimaki
    • Tomasz J. Wąsowicz
    • Robert Richter
    2021 Full text JOURNAL OF PHYSICAL CHEMISTRY A

    Dissociation of water molecules after soft X-ray absorption can yield neutral fragments in high-Rydberg (HR) states. We have studied the production of such fragments by field ionization and ion time-of-flight (TOF) spectrometry. Neutral HR fragments are created at all resonances below the O 1s ionization potential (IP) and particularly within 1 eV above the O 1s IP. The latter effect is due to the recapture of the O 1s photoelectrons into HR orbitals of the molecular water ion after the emission of a fast Auger electron. H2O+(HR) fragments subsequently dissociate, yielding neutral H(HR) and O(HR) fragments, as were found by measuring the TOF spectra by pulsed field ionization. Such measurements were carried out at the O 1s → 4a1 and 2b2 resonances as well as just above the O 1s IP. The TOF spectra also reveal two series of oscillatory structures that are attributed to quantum beats involving Lyman emission in one of the series and field ionization of H(HR) fragments in the other series.

  • Software-Defined NB-IoT Uplink Framework - The Design, Implementation and Use Cases
    • Alicja Olejniczak
    • Olga Błaszkiewicz
    • Krzysztof Cwalina
    • Piotr Rajchowski
    • Jarosław Sadowski
    2021 Full text SENSORS

    In the radiocommunication area, we may observe a rapid growth of new technology, such as 5G. Moreover, all the newly introduced radio interfaces, e.g., narrowband Internet of Things (NB-IoT), are strongly dependent on the software. Hence, the radiocommunication software development and optimization, as well as the 3GPP technical specification, should be introduced at the academic level of education. In this paper, a software-defined NB-IoT uplink framework in the field of design is presented, as well as its realization and potential use cases. The framework may be used as an academic tool for developing, investigating, and optimizing the digital transmitter paths. The roposed realization is focused on the key elements in the physical layer of the NB-IoT interface used in the sensor devices. Furthermore, the paper also highlights the need of the data processing optimization to minimize the power consumption and usage of the resources of the NB-IoT node during transmitting gathered telemetric data.

  • Soiling Effect Mitigation Obtained by Applying Transparent Thin-Films on Solar Panels: Comparison of Different Types of Coatings
    • Małgorzata Rudnicka
    • Ewa Klugmann-Radziemska
    2021 Full text Materials

    Dust accumulation on the front cover of solar panels is closely linked to location and orientation of photovoltaic (PV) installation. Its build-up depends on the module tilt angle, frequency of precipitation, humidity, wind strength and velocity, as well as grain size. Additionally, soil composition is determined by solar farm surroundings such as local factories, agricultural crops, and traffic. Over time, molecules of atmospheric dust agglomerate on top of each other and cause gradual reduction in generated energy. Manual cleaning techniques are required to restore working conditions of PV installation to their original conditions; however, they are time consuming and may lead to damage of the glass coverage. Therefore, implementing a different approach by utilizing self-cleaning and anti-dust coatings on front covers of module surfaces is thought of as a competitive manner of cleansing. Based on the varying properties of such thin-films, a division was made into hydrophobic, hydrophilic, and anti-dust coatings. In this article, the authors would like to present a comprehensive review of those types of transparent films. Moreover, a few hydrophobic coatings available on the Polish market were analyzed by applying them on glass tiles and covering them with three types of dust.

  • Solubility of Carbon Dioxide in Deep Eutectic Solvents Based on 3-Amino-1-Propanol and Tetraalkylammonium Salts at Low Pressure
    • Iwona Cichowska-Kopczyńska
    • Dorota Warmińska
    • Bartosz Nowosielski
    2021 Full text Materials

    Deep eutectic solvents (DESs) became an object of a great interest as an alternative to ionic liquids (ILs) and commonly used in CO2 capture amine solutions. In the present study, five different DESs based on 3-amino-1-propanol as physical-chemical CO2 absorbents were used. The composition was chosen in order to estimate the effects of hydrogen bond acceptor:hydrogen bond donor (HBA:HBD) molar ratio, anion type and length of alkyl chain of composing salt. The Fourier Transform Infrared (FTIR) spectroscopy was used to confirm chemical reaction. The solubility of CO2 was measured at low pressures up to 170 kPa at the temperature range of 293–318 K. Viscosity, polarity and Kamlet–Taft parameters were determined in order to estimate the dependences of the parameters and the CO2 capacity. CO2 uptake was observed to improve with decreasing molar ratio of hydrogen bond donor. Comparing the CO2 capacity of [TBAC]-based DESs, at the approximate pressure of 50 kPa, it was observed that the capacity increased in the following order of molar ratios—1:8 < 1:6 < 1:4 and a decrease in molar ratio from 1:8 to 1:4 resulted in about a 100% increase of capacity. Compared to [TBAC][AP] DESs, the [TEAC][AP] 1:4 and [TBAB][AP] 1:4 exhibited higher CO2 uptake, though the best results were obtained for [TBAB][AP].

  • Solvothermal growth of {0 0 1} exposed anatase nanosheets and their ability to mineralize organic pollutants. The effect of alcohol type and content on the nucleation and growth of TiO2 nanostructures
    • Szymon Dudziak
    • Marta Kowalkińska
    • Jakub Karczewski
    • Marcin Pisarek
    • Katarzyna Siuzdak
    • Adam Kubiak
    • Katarzyna Siwińska-Ciesielczyk
    • Anna Zielińska-Jurek
    2021 Full text APPLIED SURFACE SCIENCE

    Herein, the series of {0 0 1} exposed anatase nanosheets from HF-assisted solvothermal growth synthesis were obtained. The two-dimensional TiO2 were characterized, including both bulk (XRD, DR-UV–Vis, Mott-Schottky) and surface characteristics (N2 sorption, XPS, SEM) with experimental results compiled with Density Functional Theory (DFT) calculations. The effect of alcohol amount and type was studied, demonstrating the crucial role of nucleation rate on the final material properties, which was connected with the possible ligand exchange between F− and ROH in the [TiF6]2− octahedra, leading to further TiO2 condensation through an ether elimination reaction. Highly active 2D nanoparticles were easily obtained for different reaction times when a moderate amount of n-butanol or n-hexanol was introduced to the synthesis. The photoactivity of 2D TiO2 with exposed {0 0 1} facet strongly depended on the photocatalytic available surface area with an increased amount of ortho–hydroxyphenol (catechol) formed as a by-product. Meanwhile, the rise of n-butanol or n-hexanol content during solvothermal reaction or changing it to ethanol allowed to form smaller and more crystalline anatase particles, but their activity was hindered. For these samples, the slow phenol disappearance and no catechol formation occurred due to (i) a lower amount of adsorbed fluorine, (ii) band position shifting towards lower values, and (iii) the surface presence of Ti3+, which prevented the generation of radical dotOH radicals. It was also found that changing the nucleation rate by modifying the reaction environment influences the fluorine ions distribution, determining the final properties of 2D structure photocatalyst.

  • Solvothermal synthesis and structural characterization of three polyoxotitanium-organic acid clusters
    • Katarzyna Kazimierczuk
    • Marco Milanesio
    • Anna Dołęga
    • Luca Palin
    • Maja Walencik
    • Michał Jurkowski
    • Eleonora Conterosito
    2021 Full text RSC Advances

    Three new titanium oxo-clusters Ti4O2(OiPr)10(OOCPhMe)2 (I), Ti6O4(OEt)8(OOCPhMe)8 (II) and Ti6O6(OEt)6(OOCCHPh2)6 (III) were obtained by easy one-step solvothermal reactions of titanium(IV) isopropoxide, alcohols and carboxylic acids. The three compounds were characterized by single-crystal and powder X-ray diffraction, TGA/DSC, optical and electron microscopy, and FTIR and NMR spectroscopy. X-ray powder diffraction and spectroscopy confirmed the purity of the compounds. Structural analysis indicates that in all compounds the titanium(IV) ions are six-coordinated (distorted octahedra). (I) is a tetranuclear complex containing a Ti4(m4-O)(m2-O) core, which is linked by two (m2- OOCPhMe), four (m2-OiPr) and six OiPr ligands. (II) and (III) are hexanuclear complexes with different cores, respectively Ti6(m3-O)2(m2-O)2 and Ti6(m3-O)6. The coordination sphere of the Ti atoms is filled by eight (m2-OOCPhMe), two (m2-OEt) and six OEt in (II) and six (m2-OOCHPh2) and six OEt in (III). Different steric hindrance of substituents attached to the carboxyl group or different concentrations lead to three main different cluster geometries with two ligands. The tetranuclear and the hexanuclear clusters were obtained with the OOCPhMe ligand, while the hexagonal prism cluster was obtained with the OOCCHPh2 ligand. Hirshfeld surface calculations indicated that the packing is driven by C–O/H–C weak hydrogen bonds. The clusters can be used as molecular models of organic molecules bonded to titania surface, used in organic photovoltaic (dye sensitized solar cells) or other optoelectronic applications.

  • Some Aspects of Shear Behavior of Soft Soil–Concrete Interfaces and Its Consequences in Pile Shaft Friction Modeling
    • Jakub Konkol
    • Kamila Mikina
    2021 Full text Materials

    This paper examines the stiffness degradation and interface failure load on soft soil–concrete interface. The friction behavior and its variability is investigated. The direct shear tests under constant normal load were used to establish parameters to hyperbolic interface model which provided a good approximation of the data from instrumented piles. Four instrumented piles were used to obtain reference soil–concrete interface behavior. It was found that the variability of the friction characteristics is the highest for organic clays and the lowest for organic silts. The intact samples exhibit lower shear strength than reconstituted ones. The adhesion varies significantly depending on interface and soil type, which can result in high scatter of the skin friction prediction. The analysis of parameters variability can be used to determine the upper and lower bound of friction behavior on the interface at constant normal load condition. The backward shearing results in decrease in shear strength up to 40% of the precedent forward phase but higher initial stiffness by a factor of between 2 and 3. Presented research provides basic shear and stiffness parameters for four soft soils (organic clay, organic silt, peat, and silty loam) and gives information about variability of interface characteristics.

  • Some variants of perfect graphs related to the matching number, the vertex cover and the weakly connected domination number
    • Sergio Bermudo
    • Magda Dettlaff
    • Magdalena Lemańska
    2021 DISCRETE APPLIED MATHEMATICS

    Given two types of graph theoretical parameters ρ and σ, we say that a graph G is (σ, ρ)- perfect if σ(H) = ρ(H) for every non-trivial connected induced subgraph H of G. In this work we characterize (γw, τ )-perfect graphs, (γw, α′)-perfect graphs, and (α′, τ )-perfect graphs, where γw(G), τ (G) and α′(G) denote the weakly connected domination number, the vertex cover number and the matching number of G, respectively. Moreover, we give conditions on a graph to have equalities between these three parameters.

  • "sopockie pomieszkiwanie" [w:] Sopot oczami archiektów
    • Agnieszka Kurkowska
    2021

    udział w inicjatywie grupy ARCHART 2021 i w projekcie plenerowo-wystawienniczym "Architekci Malują Sopot"

  • Sounding rocket vibration mechanical filter and amplifier
    • Adam Dąbrowski
    • Szymon Krawczuk
    • Jacek Goczkowski
    • Karol Pelzner
    2021 Full text

    Measuring accelerations and vibrations of a sounding rocket provides both information for engineers on the launcher vehicle performance as well as environment description for future payload designers. Typically, information on the level of vibration and eigenfrequencies are required to properly design a payload. This paper presents a design of a novel mechanical filter and amplifier for mechanical vibrations. Its key feature is the possibility to tune to a specific frequency so that it acts as a bandpass filter. Its application enables widening the sensing range of a vibration sensor, such as an accelerometer, a strain gauge or a contactless sensor. The device has been successfully validated on a small sounding rocket and provided detailed description of the rocket’s dynamic behaviour. Conclusions from the flight campaign as well as possibilities for other applications are discussed. Application of the sensor can result in better insight into the launch vehicle dynamics, thus resulting in the improvement of overall sounding rocket performance.

  • Sources and composition of chemical pollution in Maritime Antarctica (King George Island), part 2: Organic and inorganic chemicals in snow cover at the Warszawa Icefield
    • Danuta Szumińska
    • Joanna Potapowicz
    • Małgorzata Szopińska
    • Czapiewski Sebastian
    • Ulrike Falk
    • Marcin Frankowski
    • Żaneta Polkowska
    2021 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    The study area is located on King George Island, where 90% of the area is permanently glaciated. This study provides a comprehensive analysis of the inorganic and organic chemistry of snow cover in the icefield and a comparison against previous results obtained in fresh water. Snow samples were collected in the summer of 2017 in the Warszawa Icefield area. Sampling points are located along two transects: between the Arctowski Polish Polar Station and the Carlini Base (N = 4), and from the forefield to the upper part of Ecology Glacier (N = 5). In the snow samples, (1) basic ions, (2) major trace metals and metalloids (and B), and (3) polycyclic aromatic hydrocarbons (PAHs) were detected and quantified. Additionally, the parameters of pH, specific electrolytic conductivity (SEC25) and total organic carbon (TOC) were determined. The results show a low concentration of inorganic elements (<30 mg/L), TOC (<1 mg/L) and PAHs (0.11–1.4 ng/L) in collected snow samples. A slight increase in PAHs and heavy-metals concentration has been observed at the marginal parts of the icefield, which suggests the impact of scientific stations. Based on this result there is a need to conduct research on pollutant levels in ice cores on King George Island to assess the risk associated with rapid glacier thawing and pollution remobilisation.

  • Space and spatial practices in times of confinement. Evidence from three European countries: Austria, France and Poland
    • Izabela Mironowicz
    • Stefan Netsch
    • Anna Geppert
    2021 Urban Design International

    In the first half of 2020, millions of people were subjected to drastic restrictions aimed at limiting the spread of the Covid-19 disease. Austria, France and Poland have implemented a lockdown to varying degrees and for varying lengths of time. This is an unprecedented situation in Europe: until now, even in times of war, curfew measures have never been applied 24 h a day. The research presented in this article was carried out in real time, in April and May 2020, with the help of urban planning students from three countries. Its objective is to observe the interaction between these measures and the urban space in two dimensions. On the one hand, we analyse the impact of these measures on the urban space and on the spatial practices of the inhabitants. On the other hand, we examine the conditions which different types of urban and rural space have provided for the inhabitants experiencing confinement. This empirical study leads to a discussion and recommendation for the town planners of the future.

  • Spatial differentiation of road safety in Europe based on NUTS-2 regions
    • Joanna Wachnicka
    • Katarzyna Palikowska
    • Wojciech Kustra
    • Kieć Mariusz
    2021 Full text ACCIDENT ANALYSIS AND PREVENTION

    Road safety varies significantly across the regions in Europe. To understand the factors behind this differentiation and the effects they have, data covering 263 NUTS-2 (Nomenclature of Territorial Units for Statistics) regions across Europe (European Union and Norway) have been analysed. The assessment was made using Geographically Weighted Regression (GWR). As a dependent variable the Road Fatality Rate (RFR – number of fatalities in a given year per one million population of the region) was used. The GWR was developed from 2014 data and took account of variables that characterise economic, infrastructural and social development. The model was validated using 2016–2018 data. The following factors were found to be statistically significant: gross domestic product per person (GDPPC), number of passenger cars per inhabitant (MRPC), share of passenger vehicles (PPC), life expectancy at birth (LIFE), as well as variables related to the border of the regions, innerborder (IB) and outerborder (OB). Results suggest that the GWR has an advantage over the global linear model which does not address regional proximity. The model allows for identification of the differences in the level of road safety in regions, estimated on the basis of the RFR and the available data in Eurostat databases. This in turn allows for indicating regions in which activities to improve road safety should have the highest priority. The model shows a large spatial diversity of factors affecting the RFR, which indicates the need to take different actions to improve road safety depending on the region. The results suggest that the GWR model can be useful for predicting and more efficient management of road safety at the regional level in Europe.

  • Spatial Modelling in Environmental Analysis and Civil Engineering
    • Artur Janowski
    • Jakub Szulwic
    • Paweł Tysiąc
    2021 Full text Applied Sciences-Basel

    As can be seen, Spatial Modelling in Environmental Analysis and Civil Engineering applies to a multitude of applications. In an attempt to bring the topic closer to potential readers, the special issue referred to security methods, optimization of calculations, conducting measurements and empirical tests. Each article has made an original contribution to the development of practical science that can be replicated by researchers around the world. Being aware of the multitude of technological solutions and possible applications, we want to promote this type of research.

  • Spawanie ramy motocyklowej ze stopu aluminium metodami TIG i MIG
    • Dariusz Fydrych
    • Anna Janeczek
    • Sławomir Bania
    2021 Full text Przegląd Spawalnictwa

    Naprawa uszkodzonych elementów konstrukcji technologiami spawalniczymi może pozwolić na przedłużenie ich eksploatacji przy stosunkowo niskich kosztach i krótkim czasie wyłączenia z użytkowania. W pracy porównano cztery technologie spawania ramy motocyklowej Kawasaki wykonanej ze stopu aluminium PA11 (AW 5754, Wr. nr. 3.3535, AlMg3). Spawanie przeprowadzono procesami TIG oraz MIG z wykorzystaniem materiałów dodatkowych AlSi5, AlMg5Mn i AlMg5Cr. Złącza zostały poddane wstępnym badaniom: wizualnym oraz badaniom niszczącym - statycznej próbie rozciągania i pomiarom twardości metodą Vickersa. Stwierdzono, że obydwie metody spawania są możliwym do zastosowania sposobem naprawy ramy, a materiały dodatkowe zawierające Mg pozwalają uzyskać złącze spawane o wytrzymałości na rozciąganie około 10 MPa wyższej, niż spoiwo AlSi5. Twardość spoiny wykonanej z użyciem materiału dodatkowego AlSi5 była wyższa o 14 do 22 HV10 niż twardość spoin wykonanych ze spoiwami AlMg5Mn i AlMg5Cr.

  • Special Issue "Applications of Finite Element Modeling for Mechanical and Mechatronic Systems"
    • Marek Krawczuk
    • Magadalena Palacz
    2021 Full text Applied Sciences-Basel

    Numerical modeling is very important in today's engineering because, among other things, it reduces the costs associated with prototyping or predicting the occurrence of potentially dangerous situations during operation in certain defined conditions. Different methods have so far been used to implement the real structure into the numerical version. The most popular have been variations of the finite element method (FEM). The aim of the proposed Special Issue is to familiarize the reader with the latest applications of the finite element method for the modeling and analysis of diverse mechanical problems.

  • Spectacular Oxygen Evolution Reaction Enhancement through Laser Processing of the Nickel‐Decorated Titania Nanotubes
    • Jakub Wawrzyniak
    • Jakub Karczewski
    • Emerson Coy
    • Igor Iatsunskyi
    • Jacek Ryl
    • Maria Gazda
    • Katarzyna Grochowska
    • Siuzdak Katarzyna
    2021 Advanced Materials Interfaces

    The selective, laser‐induced modification of the nickel‐decorated titania nanotubes provides remarkable enhancement toward oxygen evolution reaction. Particularly, the irradiation of the laterally spaced crystalline TiO2 nanotubes, results in the formation of the tight closure over irradiated end, preserving their hollow interior. The shape of the absorbance spectra is modulated along with applied energy, and the new absorption band appears at 500 nm, where the local minimum can be found for bare nanotubes. The high‐resolution X‐ray photoelectron spectra indicate the presence of both metallic and hydroxide forms of nickel species. The electrode material treated with 355 nm pulses at 50 mJ cm−2 shows significantly improved current densities in the anodic regime, reaching nearly 300 mA cm−2 while exposed to solar radiation, whereas the untreated sample barely comes to 1.5 mA cm−2 in the same conditions. The tailored titania photoanode also exhibits two orders of magnitude higher donor concentration in comparison to the primary substrate as verified by Mott–Schottky analysis. The electrochemical analysis confirms the key role of laser annealing in enhancing the effectiveness of light‐driven water splitting

  • Spectacular Oxygen Evolution Reaction Enhancement Through Laser Processing of the Nickel-Decorated Titania Nanotubes
    • Jakub Wawrzyniak
    • Jakub Karczewski
    • Emerson Coy
    • Igor Iatsunskyi
    • Jacek Ryl
    • Maria Gazda
    • Katarzyna Grochowska
    • Siuzdak Katarzyna
    2021 Full text Advanced Materials Interfaces

    The selective, laser-induced modification of the nickel-decorated titania nanotubes provides remarkable enhancement toward oxygen evolution reaction. Particularly, the irradiation of the laterally spaced crystalline TiO2 nanotubes, results in the formation of the tight closure over irradiated end, preserving their hollow interior. The shape of the absorbance spectra is modulated along with applied energy, and the new absorption band appears at 500 nm, where the local minimum can be found for bare nanotubes. The high-resolution X-ray photoelectron spectra indicate the presence of both metallic and hydroxide forms of nickel species. The electrode material treated with 355 nm pulses at 50 mJ cm−2 shows significantly improved current densities in the anodic regime, reaching nearly 300 mA cm−2 while exposed to solar radiation, whereas the untreated sample barely comes to 1.5 mA cm−2 in the same conditions. The tailored titania photoanode also exhibits two orders of magnitude higher donor concentration in comparison to the primary substrate as verified by Mott–Schottky analysis. The electrochemical analysis confirms the key role of laser annealing in enhancing the effectiveness of light-driven water splitting.

  • SPECTRAL RESPONSE OF STATIONARY JACK-UP PLATFORMS LOADED BY SEA WAVES AND WIND USING PERTURBATION METHOD
    • Bogdan Rozmarynowski
    • Wojciech Jesien
    2021 Full text Polish Maritime Research

    The paper addresses non-linear vibrations of offshore jack-up drilling platforms loaded by sea waves and wind in their stationary condition using the perturbation method. Non-linearity of dynamic equations of motion for fixed offshore platforms yields from two factors. The first is load excitation generating non-linear velocity coupling in a dynamic system. This coupling is inherent in the modified Morison equation, involving the excitation function in the form of the sum of the inertial and velocity forces of sea waves, taking into account relative wave–structure kinematics. Moreover, the wind acting on the exciting side causes similar effects. The second source is the subsoil‒structure interaction problem, modelled by a system of springs and dashpots that yields stochastic non-linearity of the dynamic system. The matrix equations of structural motion in FEM terms are set up. The perturbation method is adopted to determine the mechanical response of the system, making it possible to determine response spectra of the first and the second approximations for displacements and internal forces of the platform. The paper is the continuation of research detailed in the paper [1]. It is assumed, that the fluctuation parts of the dynamic loading forces are in line with the direction of sea wave propagation. Sea current and lift forces effects are neglected in this study. A numerical example refers to structural data of the Baltic drilling platform in the stationary configuration, i.e. when three legs support the deck above the seawater level.

  • Speed observer of induction machine based on backstepping and sliding mode for low‐speed operation
    • Marcin Morawiec
    • Arkadiusz Lewicki
    • Filip Wilczyński
    2021 Full text ASIAN JOURNAL OF CONTROL

    This paper presents a speed observer design based on backstepping and slidingmode approaches. The inputs to the observer are the stator current and thevoltage vector components. This observer structure is extended to the integra-tors. The observer stabilizing functions contain the appropriate sliding surfaceswhich result from the Lyapunov function. The rotor angular speed is obtainedfrom the non‐adaptive formula with a sliding mode mechanism. It allowsimprovement of the robustness of parameters uncertainties and the zero rotorspeed to work (near to the unobservable region). In the sensorless controlsystem, the classical first‐order sliding‐mode controllers are applied with thetransformation of the multi‐scalar variable. The proposed control system struc-ture can be named full‐decoupled due to multi‐scalar variables transformationand the feedback control law obtained from the Lyapunov theorem. The theo-retical derivations are verified in experimental waveforms. The sensorlesscontrol system's robustness is verified in the experimental investigations byusing the nominal machine parameters uncertainties method.

  • Speed Observer Structure of Induction Machine Based on Sliding Super-Twisting and Backstepping Techniques
    • Marcin Morawiec
    • Arkadiusz Lewicki
    2021 Full text IEEE Transactions on Industrial Informatics

    This paper presents an analysis of the two speed observer structures which are based on the backstepping and sliding super twisting approach. The observer stabilizing functions result from the Lyapunov theorem. To obtain the observer tuning gains the observer structure is linearized near the equilibrium point. The rotor angular speed is obtained from non-adaptive dependence. In the sensorless control system structure the classical PI controllers and transformation to the multi-scalar variables are applied. The theoretical derivations are verified in experimental waveforms. Comparison of both speed observer structures is presented for nominal speed, load torque injections while regenerating mode, very low speed range and the uncertainties of nominal parameters of induction machine.

  • Spin and Orbital Effects on Asymmetric Exchange Interaction in Polar Magnets: M(IO3)2 (M = Cu and Mn)
    • Ebube E. Oyeka
    • Michał Winiarski
    • Maurice Sorolla II
    • Keith M. Taddei
    • Allen Scheie
    • Thao Tran
    2021 INORGANIC CHEMISTRY

    Magnetic polar materials feature an astonishing range of physical properties, such as magnetoelectric coupling, chiral spin textures, and related new spin topology physics. This is primarily attributable to their lack of space inversion symmetry in conjunction with unpaired electrons, potentially facilitating an asymmetric Dzyaloshinskii–Moriya (DM) exchange interaction supported by spin–orbital and electron–lattice coupling. However, engineering the appropriate ensemble of coupled degrees of freedom necessary for enhanced DM exchange has remained elusive for polar magnets. Here, we study how spin and orbital components influence the capability of promoting the magnetic interaction by studying two magnetic polar materials, α-Cu(IO3)2 (2D) and Mn(IO3)2 (6S), and connecting their electronic and magnetic properties with their structures. The chemically controlled low-temperature synthesis of these complexes resulted in pure polycrystalline samples, providing a viable pathway to prepare bulk forms of transition-metal iodates. Rietveld refinements of the powder synchrotron X-ray diffraction data reveal that these materials exhibit different crystal structures but crystallize in the same polar and chiral P21 space group, giving rise to an electric polarization along the b-axis direction. The presence and absence of an evident phase transition to a possible topologically distinct state observed in α-Cu(IO3)2 and Mn(IO3)2, respectively, imply the important role of spin–orbit coupling. Neutron diffraction experiments reveal helpful insights into the magnetic ground state of these materials. While the long-wavelength incommensurability of α-Cu(IO3)2 is in harmony with sizable asymmetric DM interaction and low dimensionality of the electronic structure, the commensurate stripe AFM ground state of Mn(IO3)2 is attributed to negligible DM exchange and isotropic orbital overlapping. The work demonstrates connections between combined spin and orbital effects, magnetic coupling dimensionality, and DM exchange, providing a worthwhile approach for tuning asymmetric interaction, which promotes evolution of topologically distinct spin phases.

  • Spontaneous electron emission vs dissociation in internally hot silver dimer anions
    • Patryk Jasik
    • Jan Franz
    • Dariusz Kędziera
    • Tymon Kilich
    • Jan Kozicki
    • Józef Eugeniusz Sienkiewicz
    2021 Full text JOURNAL OF CHEMICAL PHYSICS

    Referring to a recent experiment, we theoretically study the process of a two-channel decay of the diatomic silver anion (Ag2-), namely the spontaneous electron ejection giving Ag2 + e- and the dissociation leading to Ag- + Ag. The ground state potential energy curves of the silver molecules of diatomic neutral and negative ion were calculated using proper pseudo-potentials and atomic basis sets. We also estimated the non-adiabatic electronic coupling between the ground state of Ag2- and the ground state of Ag2 + e-, which in turn allowed us to estimate the minimal and mean values of the electron autodetachment lifetimes. The relative energies of the rovibrational levels allow the description of the spontaneous electron emission process, while the description of the rotational dissociation is treated with the quantum dynamics method as well as time-independent methods. The results of our calculations are verified by comparison with experimental data.

  • Sprzętowa implementacja transformacji Hougha w czasie rzeczywistym
    • Paweł Kowalski
    • Robert Smyk
    2021 Full text Poznan University of Technology Academic Journals. Electrical Engineering

    W artykule przedstawiono implementację sprzętową w FPGA algorytmu do wykrywania kształtów aproksymowanych zbiorem linii prostych podczas przetwarzania obrazu cyfrowego w czasie rzeczywistym. W opracowanej strukturze sprzętowej podniesiono efektywność przetwarzania poprzez zastosowanie przetwarzania przepływowego, lookup table, wykorzystanie wyłącznie arytmetyki liczb całkowitych oraz rozproszenie pamięci głosowania. Eksperymentalnie wykorzystano przedstawioną strukturę w torze przetwarzania obrazu w czasie rzeczywistym złożonym z kamery OV7670, płyty deweloperskiej Terasic DE10-nano oraz monitora podłączonego za pomocą HDMI. Pełny tor przetwarzania został zaimplementowany w pojedynczym układzie FPGA Intel Cyclone V. Maksymalna prędkość przetwarzania obrazu z wykorzystaniem opracowanej implementacji została określona na 275 MHz.

  • SrCe0.9In0.1O3-δ-based reversible symmetrical Protonic Ceramic Cell
    • Wojciech Skubida
    • Kun Zheng
    • Anna Stępień
    • Konrad Świerczek
    • Alicja Klimkowicz
    2021 MATERIALS RESEARCH BULLETIN

    In-doped SrCe0.9In0.1O3-δ (SCI) perovskite-type oxide is utilized as the solid electrolyte, as well as a component, together with SrFe0.75Mo0.25O3-δ (SFM) compound, in the composite-type electrodes to construct symmetrical Protonic Ceramic Fuel Cells (PCFC). With good mutual stability of SCI and SFM at high temperatures in water vapor-containing reducing and oxidizing conditions, as well as sufficient ionic conductivity with high proton transference number of SrCe0.9In0.1O3-δ, and high electronic conduction of SrFe0.75Mo0.25O3-δ, effectiveness of the electrochemical reactions is ensured. It is documented that 80:20 wt.% SFM-SCI electrode performs better, comparing to the one having 50:50 wt.% ratio of both compounds, with both electrodes showing lower polarization resistance values in the reducing conditions. Symmetrical SCI-SFM|SCI|SCI-SFM cells can be operated in normal (PCFC) and reversed, Protonic Ceramic Electrolyzer Cell (PCEC) mode, showing similar shape of current density-voltage characteristics. The maximum obtained power density is 32 mW cm−2 at 800 °C.

  • S-scheme heterojunction Bi2O3-ZnO/Bentonite clay composite with enhanced photocatalytic performance
    • V. Landge
    • S.h. Sonawane
    • M. Sivakumar
    • S.s. Sonawane
    • G. U. Babu
    • Grzegorz Boczkaj
    2021 Sustainable Energy Technologies and Assessments

    The industrial waste water is always a bottleneck problem in the modern civilization of the present era. In a quest to develop effective methods for the elimination of lethal pollutants from the waste water and water remediation, this work is focused on the development of a rapid and proficient approach for preparing supported binary metal oxide catalyst for photocatalytic advance oxidation process used in waste water treatment applications. The sonochemical synthesis of novel S-scheme Bi2O3-ZnO supported on bentonite clay nanocomposite is demonstrated for the photocatalytic oxidation of Congo red (CR). The effectiveness of catalyst to degrade CR dye was determined using UV–visible spectroscopy under different experimental conditions such as catalyst loading, time of UV exposure and concentration of H2O2. The synthesized catalyst demonstrated excellent photocatalytic oxidation under UV light. The pseudo-first-order rate constant obtained for this reaction was 0.029 min−1. Nearly total degradation of CR dye was achieved in 1 h under UV light irradiation using the catalyst. This remarkable increase in the catalytic performance of Bi2O3-ZnO/bentonite clay is due to the S-scheme mechanism of charge transfer between ZnO and Bi2O3, through enhanced redox potential. Also, its efficient recoverability and reusability (5 times) establish its promising potential for catalytic applications.

  • Stability Analysis of Shunt Active Power Filter with Predictive Closed-Loop Control of Supply Current
    • Agata Bielecka
    • Daniel Wojciechowski
    2021 Full text ENERGIES

    This paper presents a shunt active power filter connected to the grid via an LCL coupling circuit with implemented closed‐loop control. The proposed control system allows selective harmonic currents compensation up to the 50th harmonic with the utilization of a model‐based predictive current controller. As the system is fully predictive, it provides high effectiveness of the harmonic reduction, which is proved by waveforms achieved in performed tests. On the other hand, the control system is prone to loss of stability. Therefore, the paper is focused on the stability analysis of the discussed control system with the additional outer control loop of the supply current with predictive control of this current. The conducted stability analysis encompasses the assessment of system stability as a function of the coupling circuit parameter identification accuracy, whose values are implemented in the current controller, as well as parameters such as the sampling frequency and proportional–integral (PI) controller coefficients. The obtained results show that the ranges of the LCL circuit parameter identification accuracy for which the system remains stable are relatively wide. However, the most effective compensation of the supply current distortion is achieved for the parameters identified correctly, and the greatest impact on the compensation quality has the value of L1 inductance.

  • Stability analysis of single-walled carbon nanotubes embedded in winkler foundation placed in a thermal environment considering the surface effect using a new refined beam theory
    • Jena Subrat Kumar
    • S. Chakraverty
    • Mohammad Malikan
    • Francesco Tornabene
    2021 Full text MECHANICS BASED DESIGN OF STRUCTURES AND MACHINES

    This article is devoted to investigate the stability of different types of Single Walled Carbon Nanotubes (SWCNTs) such as zigzag, chiral, and armchair types which are rested in Winkler elastic foundations exposing to both the low and high temperature environments. Also, the Surface effects which include surface energy and surface residual stresses, are taken into consideration in this study. It may be noted that the surface energy aids in the increase of the flexural rigidity whereas the surface residual stresses act as distributed transverse load. Further, the proposed model is developed by considering a novel refined beam theory namely one variable first order shear deformation beam theory along with the Hamilton’s principle. Navier’s method has been implemented to find out the critical buckling loads for Hinged-Hinged (H-H) boundary condition for zigzag, chiral, and armchair types of SWCNTs. A parametric study is also conducted to report the influence of various scaling parameters like small scale parameters, change in temperature, Winkler stiffness, and length to diameter ratio on critical buckling loads. Also, the present model is validated by comparing the results with other published work.

  • Stability and phase transition investigation of olanzapine polymorphs
    • Jiequn Tang
    • Yanqiang Han
    • Imran Ali
    • Hongyuan Luo
    • Andrzej Nowak
    • Jinjin Li
    2021 CHEMICAL PHYSICS LETTERS

    We use electrical embedded-fragment QM method with both DFT/ωB97XD/6-31G* and MP2/6-31G* to investigate the phase transformations of olanzapine. Gibbs free energy calculations predict that form I is always the most stable structure and form II is the least stable one, while form IV is more stable than form III below about 200 K but less stable above this temperature, implying a polymorphic phase transformation. This may account for why form IV has only recently been discovered as crystallizing from a polymer-based molecular dispersion. The proposed methods may provide guidance for experiments and thus promote the study of phase transitions of pharmaceutical molecules.

  • Stabilizacja podtorza z wykorzystaniem georusztów heksagonalnych
    • Remigiusz Duszyński
    • Michał Gołos
    2021 Inżynier Budownictwa

    Georuszty wielokierunkowe ograniczją przemieszczenia kruszywa, redukują deformacje podsypki tłuczniowej, wydłużają okres pomiędzy zabiegami utrzymaniowymi

  • Stabilizing forces in trapezoidal sheeting used as a part of the bracing system
    • Natalia Korcz-Konkol
    • Piotr Iwicki
    2021

    In the analysis of bracing systems imperfections of the restrained elements should be considered. According to EC3 this effect can be calculated by means of the equivalent stabilizing force, which replaces (in simplified way) initial bow imperfection of the braced element. However, alternative suggestions of the equivalent stabilizing force calculations can be also found in the literature. In this paper segment of the pitched roof with truss girders, purlins and trapezoidal sheeting was analyzed in two variants: with bar bracing and with trapezoidal cladding as a part of the bracing system (resisting in-plane forces). The influence of the imperfections of the truss girder on the axial forces in the purlins in two cases of the bracing systems were observed. Geometrically nonlinear analysis using shell elements was performed in Abaqus. Initial imperfections of the truss girder were implemented in direct way (by importing imperfect geometry using LBA) and compare to the analytical result according to three selected methods. A few aspects that are omitted in analytical procedures were included in numerical analysis, e.g. the eccentricity between structural elements and the stiffness of selected connections. Results showed discrepancies between numerical and analytical outcomes.

  • Stabilizing forces in trapezoidal sheeting used as a part of the bracing system
    • Natalia Korcz-Konkol
    • Piotr Iwicki
    2021 ce/papers

    In the analysis of bracing systems imperfections of the restrained elements should be considered. According to EC3 this effect can be calculated by means of the equivalent stabilizing force, which replaces (in simplified way) initial bow imperfection of the braced element. However, alternative suggestions of the equivalent stabilizing force calculations can be also found in the literature. In this paper segment of the pitched roof with truss girders, purlins and trapezoidal sheeting was analyzed in two variants: with bar bracing and with trapezoidal cladding as a part of the bracing system (resisting in-plane forces). The influence of the imperfections of the truss girder on the axial forces in the purlins in two cases of the bracing systems were observed. Geometrically nonlinear analysis using shell elements was performed in Abaqus. Initial imperfections of the truss girder were implemented in direct way (by importing imperfect geometry using LBA) and compare to the analytical result according to three selected methods. A few aspects that are omitted in analytical procedures were included in numerical analysis, e.g. the eccentricity between structural elements and the stiffness of selected connections. Results showed discrepancies between numerical and analytical outcomes.

  • Stable Field Electron Emission and Plasma Illumination from Boron and Nitrogen Co‐Doped Edge‐Rich Diamond‐Enhanced Carbon Nanowalls
    • Mateusz Ficek
    • Bartłomiej Dec
    • Kamatchi J Sankaran
    • Krzysztof Gajewski
    • Piotr Tatarczak
    • Igor Wlasny
    • Andrzej Wysmolek
    • Ken Haenen
    • Teodor Gotszalk
    • Robert Bogdanowicz
    2021 Full text Advanced Materials Interfaces

    Superior field electron emission (FEE) characteristics are achieved in edge-rich diamond-enhanced carbon nanowalls (D-ECNWs) grown in a single-step chemical vapor deposition process co-doped with boron and nitrogen. The structure consists of sharp, highly conductive graphene edges supplied by a solid, diamond-rich bottom. The Raman and transmission electron microscopy studies reveal a hybrid nature of sp3-diamond and sp2-graphene in these nanowalls. The ab-initio calculations were carried out to support the experimental observations of diamond-graphene hybrid structure. Finally, this hybrid D-ECNWs is employed as a cathode in an FEE device resulting in a low turn-on field of 3.1 V µm−1, a large field enhancement factor, a high FEE Je of 2.6 mA cm−2, and long lifetime stability of 438 min. Such an enhancement in the FEE originates from the unique materials combination, resulting in good electron transport from the graphene phases and efficient FEE of electrons from the sharp edges on the nanowalls. The prospective application of these materials is displayed by employing these hybrids as cathodes in a microplasma device ensuing a low threshold voltage of 160 V and high plasma stability of 140 min, which confirms the role of these hybrid structured nanowalls in the enhancement of electron emission.

  • Standard and modified falling mass impact tests on preplaced aggregatefibrous concrete and slurry infiltrated fibrous concrete
    • K. Ramakrishnan
    • S.r. Depak
    • K.r. Hariharan
    • Sallal R. Abid
    • G. Murali
    • Daiane Cecchin
    • Roman Fediuk
    • Y.h. Mugahed Amran
    • Hakim Abdelgader
    • Jamal M. Khatibi
    2021 CONSTRUCTION AND BUILDING MATERIALS

    Although several studies have been conducted to evaluate the impact response of concrete using theAmerican Concrete Institute (ACI) 544-2R falling mass impact test, the variations in test results are themain drawback of this testing method. This study aims to reduce the variations in experimental impacttest results by introducing two simple test setup modifications; (1) using coarse or fine aggregate bed-ding as an alternative to the steel base plate, (2) the use of line or cross-notched specimens with a lineor cross-load distributing steel plate. One hundred thirty-five cylindrical discs were prepared withPreplaced Aggregate Fibrous Concrete (PAFC) and Slurry Infiltrated Fibrous Concrete (SIFCON), testedin nine groups to assess the proposed modified techniques. Steel hooked-end (2.5%) and macropolypropylene (8.0%) fibers were used to develop PAFC and SIFCON, respectively. The research findingsrevealed that using aggregate bedding increased the impact resistance by 38 to 429% for no-notch spec-imens and up to 283% for notched specimens. The presence of notches reduced the total energy absorbedby the bedding material. For instance, the specimens with a line notch and sand bedding exhibited 15 to51% lower failure impact numbers than their corresponding no-notch specimens. Considering surface-notched specimens and aggregate bedding led to a lower scattering of the impact test results, whilethe line-notched specimens exhibited lower average scattering than the cross and no-notched specimens.In general, a percentage decrease in the coefficient of variation of 30 to 74% was attained for specimenswith bedding and/or surface notch compared to reference specimens.

  • Stannates, titanates and tantalates modified with carbon and graphene quantum dots for enhancement of visible-light photocatalytic activity
    • Marta Paszkiewicz-Gawron
    • Kowalska Ewa
    • Maya Endo-Kimura
    • Julia Zwara
    • Anna Pancielejko
    • Kunlei Wang
    • Wojciech Lisowski
    • Justyna Łuczak
    • Adriana Zaleska-Medynska
    • Ewelina Grabowska-Musiał
    2021 Full text APPLIED SURFACE SCIENCE

    Most efforts in heterogeneous photocatalysis are focused on development of new and stable photoactive materials efficient in degradation of various pollutants under visible-light irradiation. In this regard, the wide-bandgap perovskite semiconductors, i.e., SrTiO3 (titanate), SrSnO3 (stannate) and AgTaO3 (tantalate), were prepared by a solvothermal method, and then modified with carbon quantum dots (CQDs) or graphene quantum dots (GQDs) co-modified with erbium. The photocactivity was investigated for: (i) toluene degradation (gas phase), (ii) phenol decomposition (aqueous phase), and (iii) inactivation of Escherichia coli K12 bacteria. It has been found that the morphology of semiconductors depends on the synthesis conditions, resulting in the formation of spherical particles, rods and faceted particles for SrTiO3, SnSrO3 and AgTaO3, respectively. Additionally, deposition of CQDs and GQDs/erbium has resulted in an enhancement of light harvesting, thus improved photoactivity under visible-light irradiation. Samples modified with both erbium and GQDs revealed much higher photoactivity than corresponding pristine and CQDs-modified samples. Moreover, all photocatalyst modified with GQDs and Er exhibited a significant antibacterial properties under visible light irradiation (λ>420 nm). Accordingly, it has been proposed that obtained semiconductors modified with QDs and Er are promising candidates as sustainable, clean and cheap materials for environmental purification under solar radiation.

  • Stanowisko badawcze do automatycznej analizy jakości transmisji koncentratora KODEŚ z interfejsami LTE, NB-IoT oraz ISM
    • Olga Błaszkiewicz
    • Robert Burczyk
    • Agnieszka Czapiewska
    • Małgorzata Gajewska
    • Sławomir Gajewski
    • Andrzej Marczak
    • Mariusz Miszewski
    • Jarosław Sadowski
    • Jacek Stefański
    2021 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Zaprezentowano podstawowe właściwości projektowanego koncentratora danych elektroenergetycznych KODEŚ oraz stanowisko badawcze do automatycznych pomiarów jakości transmisji w sieci LTE (Long Term Evolution), opracowane na potrzeby projektu badawczego. Głównym elementem stanowiska jest autorskie oprogramowanie, które umożliwia konfigurowanie urządzeń pomiarowych oraz definiowanie scenariuszy pomiarowych. Dopełnieniem tego jest dodatkowe oprogramowanie zastosowane do graficznej prezentacji otrzymanych wyników badań pomiarowych. W artykule opisano również stanowisko, wykorzystujące technikę radia programowalnego i otwarte oprogramowanie, emulujące funkcje stacji bazowej oraz terminala ruchomego sieci LTE.

  • Starter for Voltage Boost Converter to Harvest Thermoelectric Energy for Body-Worn Sensors
    • Grzegorz Blakiewicz
    • Jacek Jakusz
    • Waldemar Jendernalik
    2021 Full text ENERGIES

    This paper examines the suitability of selected configurations of ultra-low voltage (ULV) oscilla-tors as starters for a voltage boost converter to harvest energy from a thermoelectric generator (TEG). Important properties of particularly promising configurations, suitable for on-chip imple-mentation are compared. On this basis, an improved oscillator with a low startup voltage and a high output voltage swing is proposed. The applicability of n-channel native MOS transistors with negative or near-zero threshold voltage in ULV oscillators is analyzed. The results demonstrate that a near-zero threshold voltage transistor operating in the weak inversion region is most ad-vantageous for the considered application. The obtained results were used as a reference for de-sign of a boost converter starter intended for integration in 180-nm CMOS X-FAB technology. In the selected technology, the most suitable transistor available with a negative threshold voltage was used. Despite using a transistor with a negative threshold voltage, a low startup voltage of 29 mV, a power consumption of 70 µW, and power conversion efficiency of about 1.5% were achieved. A great advantage of the proposed starter is that it eliminates a multistage charge pump necessary to obtain a voltage of sufficient value to supply the boost converter control circuit.

  • State of the Art in Open Platforms for Collaborative Urban Design and Sharing of Resources in Districts and Cities
    • Barry Hayes
    • Dorota Kamrowska-Załuska
    • Aleksandar Petrovski
    • Cristina Jiménez-pulido
    2021 Full text Sustainability

    This work discusses recent developments in sharing economy concepts and collaborative co-design technology platforms applied in districts and cities. These developments are being driven both by new technological advances and by increased environmental awareness. The paper begins by outlining the state of the art in smart technology platforms for collaborative urban design, highlighting a number of recent examples. The case of peer-to-peer trading platforms applied in the energy sector is then used to illustrate how sharing economy concepts and their enabling technologies can accelerate efforts towards more sustainable urban environments. It was found that smart technology platforms can encourage peer-to-peer and collaborative activity, and may have a profound influence on the future development of cities. Many of the research and development projects in this area to date have focused on demonstrations at the building, neighbourhood, and local community scales. Scaling these sharing economy platforms up to the city scale and beyond has the potential to provide a number of positive environment impacts. However, significant technical and regulatory barriers to wider implementation exist, and realising this potential will require radical new approaches to the ownership and governance of urban infrastructure. This paper provides a concise overview of the state of the art in this emerging field, with the aim of identifying the most promising areas for further research.

  • Stateczność kratownic ze sprężystymi podporami bocznymi
    • Marcin Krajewski
    2021 Full text

    W rozprawie doktorskiej podjęto temat stateczności kratownic płaskich, które często stanowią zadaszenie stalowych budynków halowych i innych obiektów budowlanych. Głównym celem pracy było badanie zależności pomiędzy sztywnością na przesuw i obrót, sprężystych podpór bocznych a obciążeniem krytycznym i granicznym kratownic. W pracy przedstawiono rezultaty analiz numerycznych stateczności i nośności rzeczywistych kratownic poddanych obciążeniu grawitacyjnemu i obciążeniu od wiatru. Obliczenia przeprowadzono dla modeli prętowych i powłokowych badanych konstrukcji, metodą elementów skończonych, wykorzystując programy Femap i Autodesk Robot Structural Analysis. Na podstawie liniowych analiz stateczności (LBA) oraz analiz statycznych geometrycznie i fizycznie nieliniowych (GMNIA) wykazano, że w każdym przypadku istniała pewna progowa (minimalna) sztywność sprężystych podpór bocznych kratownicy zapewniająca, że nośność konstrukcji wynosiła 90% lub 95% nośności uzyskanej przy sztywnych stężeniach. W pracy analizowano wpływ kształtu i amplitudy globalnych imperfekcji geometrycznych kratownic, w postaci łukowej krzywizny ściskanych pasów oraz w formie pierwszej postaci wyboczenia, na progowe sztywności stężeń. Analizie poddano również wpływ liczby i wymiarów przewiązek, stosowanych między gałęziami pasów kratownic na nośność prętów o przekrojach złożonych. Ponadto, przeprowadzono badania doświadczalne nośności modelu kratownicy (podpartej sprężyście), poddanej obciążeniu pionowemu skierowanemu ku górze i obciążeniu grawitacyjnemu.

  • Statistical evaluation of physical and index properties of Vistula Marshlands deltaic soft soils
    • Jakub Konkol
    • Lech Bałachowski
    2021 Full text IOP Conference Series: Earth and Environmental Science

    This paper provides statistical evaluation of physical and index parameters of the Vistula Marshlands deltaic soft soils using three datasets. Soft soils from the Vistula Marshlands are grouped into the four categories: (1) silty/sandy loams, (2) organic clays, (3) organic silts and (4) peats. Variability of basic and derivative physical properties as well as Atterberg's limits and plasticity index is studied. It is found that index properties for all soil groups are characterized by large scatter (COV about 50%). The most reliable parameters for silty loams, organic clays and silts are soil density (COV<10%) and specific gravity (COV about 2%). Physical/index parameters of peats are characterized by large scatter, which indicates very local properties and individual formation process. Most of the data points for physical/index quantity are within 1SD range regardless normality of data distribution. In the main body of this paper, the quantitative physical/index properties variability is evaluated and some practical design guidelines concerning variability of deltaic soil in the Vistula Marshlands are given.

  • Sterownik PLC jako urządzenie IED zgodne ze standardem IEC 61850
    • Andrzej Augusiak
    • Mateusz Breza
    • Filip Grabowski
    2021 Full text

    Wraz z rozwojem elektroenergetyki, w stacjach i sieciach elektroenerge- tycznych instalowanych jest coraz więcej cyfrowych urządzeń i układów realizujących złożone funkcje sterowni- cze, nadzorujące i zabezpieczeniowe [1] [2]. Obecnie, większość z tych urządzeń standardowo umożliwia również zdal- ne sterowanie, monitoring i akwizycję danych, wykorzystując jeden z wielu protokołów opracowanych dla prze- mysłowych sieci komunikacyjnych. Jednym z dynamicznie rozwijających się standardów w tym zakresie jest norma IEC 61850 [3], dedykowana dla systemów automatyki w stacjach elek- troenergetycznych. Standaryzuje ona struktury danych opisujących wielo- rakie funkcje w urządzeniach elektro- energetycznych, a także wprowadza jednolite protokoły komunikacji po- między tymi urządzeniami, z wykorzy- staniem przemysłowej sieci ethernet [4]. Dzięki temu możliwa jest stosun- kowo łatwa integracja cyfrowych urzą- dzeń różnych producentów w jednej sieci komunikacyjnej, bez konieczności stosowania urządzeń pośredniczących lub tłumaczących. Wśród dostępnych na rynku urządzeń wykorzystujących standard IEC 61850 (urządzeń IED) na szczególną uwagę zasługują swobodnie programowal- ne sterowniki logiczne (PLC), które umożliwiają oprogramowanie różnych, często bardzo złożonych, funkcji użyt- kowych, a jednocześnie zapewniają zgodność tych funkcji z modelami danych IEC 61850 oraz wymianę in- formacji z innymi urządzeniami i sys- temami obsługującymi komunikację w tym standardzie (w tym z systemami SCADA). Jednym z takich bardzo wszechstron- nych urządzeń IED jest sterownik lo- giczny WAGO PFC200 (750-8212/025- 001) [5], który został udostępniony Politechnice Gdańskiej przez przedsię- biorstwo WAGO ELWAG Sp. z o.o. [6] na potrzeby realizacji projektu Cyfrowego sterownika polowego przeznaczonego do stacji DC [7].

  • STORMWATER AS AN ALTERNATIVE WATER SOURCE: QUALITY CHANGES WITH RAINFALL DURATION AND IMPLICATIONS FOR TREATMENT APPROACHES
    • Aleksandra Pieniaszek
    • Ewa Wojciechowska
    • Eliza Kulbat
    • Nicole Nawrot
    • Janusz Pempkowiak
    • Hanna Obarska-Pempkowiak
    • Krzysztof Czerwionka
    2021 Full text International Journal of Conservation Science

    The pressure on the world’s water resources is rapidly increasing due to population growth and climatic changes. Valorisation of stormwater as a water resource for non-potable reuse can reduce high-quality water demands and save it for potable uses. In this context, not only roof runoff but also drained stormwater outflow, representing considerably higher pollution levels, should be considered as a potential resource. We analysed the quality of stormwater runoff from the municipal separate sewer system in a residential catchment located in a medium-sized town in Poland. The changes in concentrations of TSS, COD, BOD5, and E. coli with rainfall duration were assessed during 7 torrential rainfalls with an intensity exceeding 15 L/s·ha. The concentrations of contaminants in the “first flush” of stormwater varied from 93 to 1598 mg/L TSS, from 112 to 815 mg O2/L for COD, and from 7 to 48 mg O2/L for BOD5 and significantly dropped with rainfall duration. The number of E.coli in stormwater outflow fluctuated from 2.5·103 to 8.1·105 MPN/100 mL. Rapid filtration on sand filters was applied in laboratory-scale for the treatment of raw stormwater outflow, providing removal efficiencies of 87-88% for COD, 50-90% for TN, and 88-96% for TP. The quality of raw and treated stormwater was discussed with regard to the existing and developing European standards for water reuse. The results from our study show that treated stormwater outflows can be applied for landscape irrigation. Moreover, rapid filtration is appropriate for stormwater treatment and can be applied either with the support of pre-sedimentation or even as the only separation process.

  • Strain sequence effect on fatigue life and fracture surface topography of 7075-T651 aluminium alloy
    • Wojciech Macek
    • Ricardo Branco
    • José Domingos Costa
    • Cândida Pereira
    2021 Full text MECHANICS OF MATERIALS

    The paper studies the effect of strain-loading sequence on fatigue lifetime and fracture surface topographies in 7075-T651 aluminum alloy specimens. Fatigue tests were performed in two ways: (i) constant-amplitude loading and (ii) two series of variable amplitude loading with non-zero mean strain values. The topography of the fatigue fractures was measured over their entire surfaces with the help of an optical confocal measurement system. The results of fatigue tests in the form of equivalent strains, εaeq, such as the weighted mean of strain components, εa1, εa2, and fatigue life, Nf, were used as the sum of the partial number of cycles N1, and N2. This study indicates, inter alia, that the values of the fracture surface parameter core height Sk, found in the two-step loading pro gram, are linearly dependent on the equivalent strain, and logarithmically dependent on the fatigue life.

  • STRAJK!
    • Krzysztof Wróblewski
    2021

    Strajk – według „Słownika wyrazów obcych" (PWN, Warszawa 1999) – to: zbiorowe, dobrowolne zaprzestanie na pewien okres pracy przez pracowników jednego lub wielu zakładów, będące formą walki o zrealizowanie ich żądań ekonomicznych lub politycznych. Lata 70. ubiegłego wieku – dziesięciolecie rządów Gierka i jego ekipy – kończył głęboki kryzys struktur władzy i gospodarki, społeczne rozgoryczenie i brak perspektyw na godne życie. Brakowało żywności, mieszkań, przysłowiowego „papieru toaletowego i sznurka do snopowiązałek". Wszystkiego. (...) 14 sierpnia 1980 roku rozpoczął się strajk w Stoczni Gdańskiej im. Lenina, który błyskawicznie podjęto w stoczniach i fabrykach Gdyni, Szczecina, Elbląga, Słupska, a następnie i innych miejscach w kraju. Oprócz żądań ekonomicznych, związanych z poprawą warunków życia, domagano się wolnych związków zawodowych. Toczyła się znacząca, rozważna gra o przyszłość kraju. Gra, którą wygrali robotnicy. Powstał niezależny, samorządny związek zawodowy SOLIDARNOŚĆ, narodził się spontaniczny ruch społeczny, który doprowadził do zmian ustrojowych i demokratyzacji życia publicznego. Strajki latem 1980 roku zmieniły bieg dziejów Polski. Istotą działań artystycznych tamtego czasu było komentowanie robotniczych i rolniczych strajków i protestów, interpretowanie istniejących w przestrzeni społecznej ograniczeń, zła, niesprawiedliwości, prześladowań. Sztuka odzwierciedlała znaczenie sprzeciwu wobec panującego reżimu, występujących wynaturzeń, rozbudowanych ograniczeń wolności i niezależności. Pomagała w zrozumieniu zachodzących zmian, inspirowała do kolejnych przemian, uświadamiała, że o wolność i dobro trzeba walczyć każdego dnia. Artyści zwracali uwagę na społeczne problemy, niepokoje i rozterki, polityczną rzeczywistość; dokumentowali polską drogę do wolności, podkreślali znaczenie i konieczność dialogu. Wystawa STRAJK! przypomina, że narodziny „Solidarności" poprzedzały Czerwiec '56, Marzec '68, Grudzień '70, Czerwiec '76, które wywołały nie tylko procesy przeobrażeń ustrojowych i społecznych, ale również przeobraziły warunki życia Polek i Polaków; spowodowały, że ludzkie działania ponownie stały się odzwierciedleniem myśli, emocji, marzeń i przekonań.

  • Strategie kontroli biokorozji
    • Edyta Malinowska-Pańczyk
    2021

    W rozdziale omówiono sposoby ograniczania destrukcyjnej działalności mikroorganizmów powodujących biokorozję.

  • Strength analysis of container ship subjected to torsional loading
    • Krzysztof Wołoszyk
    • Mateusz Jabłoński
    • Marian Bogdaniuk
    2021

    The objective of this work is to investigate the torsional response of a container ship, with particular consideration of the warping effect. Two different models are investigated. In the first case, the full length model of a ship is analyzed and a distributed load is applied with the use of a novel approach. The model is supported in the torsional centre of the cross-section, which is derived analytically. In the second case, the three cargo hold model is analyzed, where the influence of fore and aft parts of the ship is simulated by ‘end-constraint beams’. A constant, concentrated torsional moment is applied in the shear centre of the fore and aft end cross-section. The structural responses of these two models are obtained and distributions of normal stress across the critical cross-sections are derived. The studies revealed that three cargo hold model subjected to torsional moment underestimates the level of normal stresses caused by the warping effect when compared to the full-length ship model subjected to a distributed load.

  • Strong ellipticity conditions and infinitesimal stability within nonlinear strain gradient elasticity
    • Victor Eremeev
    2021 Full text MECHANICS RESEARCH COMMUNICATIONS

    We discuss connections between the strong ellipticity condition and the infinitesimal instability within the nonlinear strain gradient elasticity. The strong ellipticity (SE) condition describes the property of equations of statics whereas the infinitesimal stability is introduced as the positive definiteness of the second variation of an energy functional. Here we establish few implications which simplify the further analysis of stability using formulated SE conditions. The results could be useful for the analysis of solutions of homogenized models of beam-lattice materials at different scales.

  • Strong-coupling superconductivity of SrIr2 and SrRh2 : Phonon engineering of metallic Ir and Rh
    • Sylwia Gutowska
    • Karolina Górnicka
    • Paweł Wójcik
    • Tomasz Klimczuk
    • Bartlomiej Wiendlocha
    2021 Full text PHYSICAL REVIEW B

    Experimental and theoretical studies on superconductivity in SrIr2 and SrRh2 Laves phases are presented. The measured resistivity, heat capacity, and magnetic susceptibility confirm the superconductivity of these compounds with Tc = 6.07 and 5.41 K, respectively. Electronic structure calculations show that the Fermi surface is mostly contributed by 5d (4d) electrons of Ir (Rh), with Sr atoms playing the role of electron donors. The effect of the spin-orbit coupling is analyzed and found to be important in both materials. Lattice dynamics and electron-phonon coupling (EPC) are studied and the strong electron-phonon interaction is found, contributed mostly by the low-frequency Ir and Rh vibrations. The enhancement of EPC, when compared to weakly coupled metallic Ir and Rh, is explained by the strong modifications in the propagation of phonons in the network of Ir (Rh) tetrahedrons, which are the building blocks of the Laves phase, and originate from the metallic fcc structures of elemental iridium and rhodium.

  • Structural Adaptive, Self-Separating Material for Removing Ibuprofen from Waters and Sewage
    • Anna Skwierawska
    • Dominika Nowacka
    • Paulina Nowicka
    • Sandra Rosa
    • Katarzyna Kozłowska-Tylingo
    2021 Full text Materials

    -cyclodextrin nanosponge (CDM) was used for the adsorption of ibuprofen (IBU) from water and sewage. The obtained material was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), Barrett– Joyner–Halenda (BJH), Harkins and Jura t-Plot, zeta potential, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elementary analysis (EA). Batch adsorption experiments were employed to investigate the effects of the adsorbent dose, initial IBU concentration, contact time, electrolyte ions and humic acids, and sewage over adsorption efficiency. The experimental isotherms were show off using Langmuir, Freundlich, Hill, Halsey and Sips isotherm models and thermodynamic analysis. The fits of the results were estimated according to the Sips isotherm, with a maximum adsorption capacity of 86.21 mg g1. The experimental kinetics were studied by pseudofirst- order, pseudo-second-order, Elovich, modified Freundlich, Weber Morris, Bangham’s pore diffusion, and liquid film diffusion models. The performed experiments revealed that the adsorption process fits perfectly to the pseudo-second-order model. The Elovich and Freundlich models indicate chemisorption, and the kinetic adsorption model itself is complex. The data obtained throughout the study prove that this nanosponge (NS) is extremely stable, self-separating, and adjusting to the guest structure. It also represents a potential biodegradable adsorbent for the removal IBU from wastewaters.

  • Structural analysis as a supporting method for the research of the medieval brick architecture
    • Piotr Samól
    • Piotr Iwicki
    • Jarosław Przewłócki
    2021

    Chronology of brick historical buildings might be established much more precisely than the chronology of stone ones due to the architectural and metrical analysis of bricks, mortars and brickworks. Comparison of historical sources allows to reconstruct the previous stages of constructing monuments. Causations between transformations and developments of monuments are usually interpreted as the results of artistic or ideological influence rather than pragmatic decisions. Such explanations neglect, however, the impact of structural disasters and imperfections. Experience, delivered by the previous erroneous solutions or failures, undoubtedly influenced the further development of architecture. In this paper the authors present how numerical modelling and structural analysis of complex historical brick buildings and different stages of their alterations might be used as a supporting method for the research of their history. Consequently, modern numerical tools for structural analysis can also be useful in investigating of the process of creating architectural solutions [1]. Because more accurate historical analyses belong to the qualitative research, it is not possible to examine very wide group of different monuments. Therefore the authors chose for that purpose the homogeneous group of the mendicant orders’ medieval churches in the former State of Teutonic Order in Prussia, which have been the subject of authors’ in situ research since 2009 [2]. This group is thought to be representative for the medieval techniques of the brick architecture in northern Europe and Baltic Sea Region. The aim of this research is to find out whether structural analysis might be carried out in a historical building in which consecutive transformations partially erased its original form (reconstructed on the base of the architectural and archaeological research)? A positive answer to that question allows to put another one – about whether the numerical modelling of the structure of monument might give some additional information on its history? The results of described research might give a new tool for conservators, architects, archaeologists and engineers in their research and other conducting works.