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Repozytorium publikacji
Politechniki Gdańskiej

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  • Historia rozwoju trakcji elektrycznej i jej obecność na Politechnice Gdańskiej
    • Jacek Skibicki
    2020 Pełny tekst Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    W artykule przedstawiono zarys historii trakcji elektrycznej w świetle obecności i rozwoju tej dyscypliny na Politechnice Gdańskiej. Szczególnie skupiono się na rozwoju transportu zelektryfikowanego w rejonie Pomorza Gdańskiego z perspektywy prac wykonywanych przez pracowników Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej.

  • HISTORY OF INITIAL ENERGY AND WATER NETWORK DEVELOPMENT IN QATAR
    • Mohd Zaman
    • Marek Olesz
    2020 Pełny tekst Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    Qatar: A country which had to be associated with neighboring countries like UAE or Saudi Arabia for people to know about it, stands proud today due to the ample production and exporting of Black Gold. A country with almost no vegetation or suitable weather to harvest crops, turned from being heavily dependent on trading Pearls to exporting natural oil and gas to all over the globe. The paper outlines in details the history of the development of Energy sector in the State of Qatar. Being under British protection around the Arabian sea and Ottoman Empire from Land, there was not much of interest in this region. However, the scenario changed drastically after the discovery of Oil in 1938. Being able to produce and export the oil in huge quantity, it took Qatar less than 40 years to transform its energy sector totally. The paper describes these post oil discovery developments in the energy sector of the State of Qatar and links History to the Present.

  • Homoclinics for singular strong force Lagrangian systems
    • Marek Izydorek
    • Joanna Janczewska
    • Jean Mawhin
    2020 Pełny tekst Advances in Nonlinear Analysis

    We study the existence of homoclinic solutions for a class of generalized Lagrangian systems in the plane, with a C1-smooth potential with a single well of infinite depth at a point ξ and a unique strict global maximum 0 at the origin.Under a strong force condition around the singular point ξ, via minimization of an action integral, we will prove the existence of at least two geometrically distinct homoclinic solutions.

  • Homoleptic mono-, di-, and tetra-iron complexes featuring phosphido ligands: a synthetic, structural, and spectroscopic study
    • Kinga Kaniewska
    • Łukasz Ponikiewski
    • Natalia Szynkiewicz
    • Bartłomiej Cieślik
    • Jerzy Pikies
    • J. Krzystek
    • Alina Dragulescu-Andrasi
    • Sebastian Stoian
    • Rafał Grubba
    2020 Pełny tekst DALTON TRANSACTIONS

    We report the first series of homoleptic phosphido iron complexes synthesized by treating either the β-diketiminato complex [(Dippnacnac)FeCl2Li(dme)2] (Dippnacnac = HC[(CMe)N(C6H3-2,6-iPr2)]2) or [FeBr2(thf )2] with an excess of phosphides R2PLi (R = tBu, tBuPh, Cy, iPr). Reaction outcomes depend strongly on the bulkiness of the phosphido ligands. The use of tBu2PLi precursor led to an anionic diiron complex 1 encompassing a planar Fe2P2 core with two bridging and two terminal phosphido ligands. An analogous reaction employing less sterically demanding phosphides, tBuPhPLi and Cy2PLi yielded diiron anionic complexes 2 and 3, respectively, featuring a short Fe–Fe interaction supported by three bridging phosphido groups and one additional terminal R2P− ligand at each iron center. Further tuning of the P-substrates bulkiness gave a neutral phosphido complex 4 possessing a tetrahedral Fe4 cluster core held together by six bridging iPr2P moieties. Moreover, we also describe the first homoleptic phosphanylphosphido iron complex 5, which features an iron center with low coordination provided by three tBu2P-P(SiMe3)− ligands. The structures of compounds 1–5 were determined by single-crystal X-ray diffraction and 1–3 by 1H NMR spectroscopy. Moreover, the electronic structures of 1–3 were interrogated using zero-field Mössbauer spectroscopy and DFT methods.

  • Horyzontem II za koło polarne – arktyczna wyprawa polarna naukowców z Politechniki Gdańskiej
    • Klaudia Kosek
    • Małgorzata Szopińska
    • Joanna Potapowicz
    2020 Pełny tekst Pismo PG

    W dniach od 24 sierpnia do 17 września 2020 roku dr inż. Klaudia Kosek (WILiŚ), dr inż. Małgorzata Szopińska (WILiŚ) oraz mgr inż. Joanna Potapowicz (WCh) uczestniczyły w 43. Wyprawie Polarnej Instytutu Geofizyki PAN. Ekspedycja naukowa ujęta była w programie badawczym zawartym w projekcie grantowym Preludium (nr 2017/25/N/NZ9/01506), finansowanym przez Narodowe Centrum Nauki, pt. „Oznaczanie składników odżywczych, będących podstawowym czynnikiem umożliwiającym wzrost bakteriocenozy w zlewni rzeki arktycznej południowo-zachodniego Spitsbergenu”, którego kierownikiem jest dr inż. Klaudia Kosek.

  • How can Systems Thinking Help Us Handling the COVID-19 Crisis?
    • Krzysztof Zięba
    2020 Pełny tekst

    Purpose: COVID-19 pandemic outbreak remains one of the most influential events in the global economy over the recent years. While being primarily public health-related, it has a tremendous impact on many other aspects, such as public transport, education, and business management. Many businesses were forced to introduce rapid changes to their business models in order to survive. The aim of this paper is to show the complexity and inter-relations of changes triggered by COVID-19 outbreak. Understanding of this complexity is crucial for developing business resilience to similar events in the future. Methodology: The paper uses Systems Thinking approach to analyse influence of COVID-19 pandemic on business operations. Causal loop diagrams are used to show the complicated mechanisms behind the impact of pandemic on several aspects of business operation and management. Findings: Causal loop diagrams indicate that complicated relations between various elements may produce surprising and unexpected outcomes. The existing delays may result in actions bringing counterintuitive results. Perceptions of some variables play more important roles than actual variables and it often requires more than one actor to solve a particular problem – hence the need for organisational, as well as social learning. Adaptive business management may prove to be a particular challenge for small business owners. Research limitations: The paper is mostly of a conceptual nature. Causal loop diagrams require extensive data in order to be transformed into full Systems Thinking models. Hence this paper may serve as a basis for further development. Practical implications: The paper provides useful insights into the complex nature of contemporary business operation and management in the wake of a major epidemiological crisis. It may contribute to a better understanding of important factors that often tend to be disregarded and not paid enough attention to by business owners/managers. Originality/value: The paper links one of the major current challenges for the global economy with Systems Thinking, which offers a holistic perspective on business operation and management with emphasis on linkages and interactions between numerous stakeholders involved. It offers food for thought not only for academics, but also to business owners/managers, aware of the complexity of contemporary world

  • How does stakeholder pressure influence CSR-practices? A construction industry model based on a European sample
    • Rafał Kowalczyk
    2020 Pełny tekst

    The stakeholder pressure is one of the most vital powers which determines CSR implementation and can provide organizations with the motivation to adopt corporate social responsibility (CSR) strategy, as the stakeholder theory claims. The current investigation replications Kowalczyk’s (2019) study, who examined the same structure of relations based on the Polish sample. The essence of this replication is to find out whether CSR- practice is driven by ‘stakeholder pressure’ and ‘CSR-company culture’ vary when controlled by selected European countries or not. Namely, a 'European model of CSR-practice' is embedded in the European culture, or it does not exist (yet). Some earlier studies suggest that sociocultural context matters when it comes to CSR-practice. Therefore, this study aims to check how intensively European cultural context affects organizational cultural context and stakeholder pressure when influencing CSR-practices in the construction industry by employing a sample composed of selected European countries. Kowalczyk’s (2019) model was then replicated based on a convenience sample composed of 282 cases from five European countries. The structural equation modeling method (SEM) was applied to analyze data and verify hypotheses. The findings confirmed that stakeholder pressure is the most substantial influence of power on CSR-practices. Moreover, although the current study proves that CSR practice differs depending on its implementation, it does not present all aspects of the potential differences. Further, deeper research is required to understand it better.

  • How ethics combine with big data: a bibliometric analysis
    • Marta Kuc-Czarnecka
    • Magdalena Olczyk
    2020 Pełny tekst Humanities & Social Sciences Communications

    The term Big Data is becoming increasingly widespread throughout the world, and its use is no longer limited to the IT industry, quantitative scientific research, and entrepreneurship, but entered as well everyday media and conversations. The prevalence of Big Data is simply a result of its usefulness in searching, downloading, collecting and processing massive datasets. It is therefore not surprising that the number of scientific articles devoted to this issue is increasing. However, the vast majority of research papers deal with purely technical matters. Yet, large datasets coupled with complex analytical algorithms pose the risk of non-transparency, unfairness, e.g., racial or class bias, cherry-picking of data, or even intentional misleading of public opinion, including policymakers, for example by tampering with the electoral process in the context of ‘cyberwars’. Thus, this work implements a bibliometric analysis to investigate the development of ethical concerns in the field of Big Data. The investigation covers articles obtained from the Web of Science Core Collection Database (WoS) published between 1900 and July 2020. A sample size of 892 research papers was evaluated using HistCite and VOSviewer software. The results of this investigation shed light on the evolution of the junction of two concepts: ethics and Big Data. In particular, the study revealed the following array of findings: the topic is relatively poorly represented in the scientific literature with the relatively slow growth of interest. In addition, ethical issues in Big Data are discussed mainly in the field of health and technology.

  • How thermal stability of ionic liquids leads to more efficient TiO2-based nanophotocatalysts: Theoretical and experimental studies
    • Anna Rybińska-fryca
    • Alicja Mikoajczyk
    • Justyna Łuczak
    • Marta Paszkiewicz-Gawron
    • Monika Paszkiewicz
    • Adriana Zaleska-Medynska
    • Tomasz Puzyn
    2020 Pełny tekst JOURNAL OF COLLOID AND INTERFACE SCIENCE

    Ionic liquids (ILs) containing distinct nitrogen-bearing organic cations (pyridinium, pyrrolidinium, imidazolium, ammonium, morpholinium) were first used for the preparation of 23 IL-TiO2 types of composites by ionic liquid assisted solvothermal synthesis. These 23 optimal ILs structures (i.e. compounds exhibiting an optimal combination of specific properties, functionality, and safety) for synthesis and experimental validation were selected by computational high-throughput screening from a combinatorically created library containing 836 ILs theoretically designed and characterized candidates. Then, selected IL-TiO2 structures with potential photocatalytic activity were synthesized with the use of solvothermal reaction. Then, the decomposition level, the role of the individual IL cation structure on the morphology, thermal stability, surface and photocatalytic properties of the IL-TiO2 microparticles were determined experimentally. The chemoinformatic analysis of the relationship between the structure of the ionic liquid, its thermal stability under the conditions of synthesis and photocatalytic activity was applied for the first time. The results presented here are the first step in the development of methodology (combined experimental and theoretical) that may simplify the procedure of designing safer and more efficient TiO2-based photocatalyst. The developed computational methodology makes it possible to predict properties of newly synthesized IL-TiO2 materials before synthesis and identifies structural features of ILs that influence the efficiency of IL-TiO2 system. The presented approach reduces the number and cost of necessary experiments, as well as increases the success ratio of efficient TiO2-based photocatalyst design by a selection of optimal IL structures (i.e. ionic liquid characterized by a combination of most promising physicochemical features).

  • Human Feedback and Knowledge Discovery: Towards Cognitive Systems Optimization
    • Caterine Silva de Oliveira
    • Cesar Sanin
    • Edward Szczerbicki
    2020 Pełny tekst Procedia Computer Science

    Current computer vision systems, especially those using machine learning techniques are data-hungry and frequently only perform well when dealing with patterns they have seen before. As an alternative, cognitive systems have become a focus of attention for applications that involve complex visual scenes, and in which conditions may vary. In theory, cognitive applications uses current machine learning algorithms, such as deep learning, combined with cognitive abilities that can broadly generalize to many tasks. However, in practice, perceiving the environment and adapting to unforeseen changes remains elusive, especially for real time applications that has to deal with high-dimensional data processing with strictly low latency. The challenge is not only to extract meaningful information from this data, but to gain knowledge and also to discover insight to optimize the performance of the system. We envision to tackle these difficulties by bringing together the best of machine learning and human cognitive capabilities in a collaborative way. For that, we propose an approach based on a combination of Human-in-the-Loop and Knowledge Discovery in which feedback is used to discover knowledge by enabling users to interactively explore and identify useful information so the system can be continuously trained to gain previously unknown knowledge and also generate new insights to improve human decisions.

  • Hybrid Analysis of Structures Composed of Axially Symmetric Objects
    • Małgorzata Warecka
    • Rafał Lech
    • Piotr Kowalczyk
    2020 Pełny tekst IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES

    — A hybrid method for the scattering problems in shielded and open structures is presented. The procedure is based on the combination of body-of-revolution involving finite-element methods with impedance matrix formulation and the mode-matching technique, which can be utilized for the analysis of structures with axially symmetrical scatterers. In order to confirm the validity and efficiency of the proposed approach, a few examples of electromagnetic field scattering in open and waveguide structures are analyzed. The results cohere with those obtained by commercial software

  • Hybrid Expert System for Computer-Aided Design of Ship Thruster Subsystems
    • Andrzej Kopczyński
    2020 Pełny tekst IEEE Access

    The article presents an expert system supporting the design of ship's power subsystems, in particular the thruster subsystem. The proposed hybrid expert system uses the results of simulation tests as the additional source of knowledge. The results of system operation are collated in a report which can be used as part of ship design description. The work oriented on developing the expert system is the continuation of the research carried out in cooperation with the shipyard's design office, the main aim of which was to automate selected stages of the ship's design process. The hybrid expert system for computer-aided design of ship thruster subsystems can support designers by creating part of the technical description of the thruster subsystem, evaluation of static and dynamic properties, and by checking if design solutions have met the requirements of classification societies. Additionally, the expert system supports collecting and providing information about the elements and structures of the thruster subsystem. Finally, the system provides a document with the description of the thruster structure and elements used in it. The proposed expert system is dedicated to the initial design stages.

  • Hybrid Method Analysis of Unshielded Guiding Structures
    • Małgorzata Warecka
    • Rafał Lech
    • Piotr Kowalczyk
    2020 Pełny tekst

    A combination of mode matching, finite element methods and generalized impedance matrix is presented in a context of propagation problems for open guiding structures. The computational domain is divided into two regions: the first one is a circular cylinder containing whole guiding structure and the second one surrounds this artificial cylinder. The impedance matrix is calculated with the use of finite element method in the first region and fields outside are expressed by analytical functions. As a last step propagation coefficients are obtained with the use of global roots and poles finding algorithm. The results for simple dielectric ridge waveguides are presented and compared with alternative solutions.

  • Hybrid Modulation for Modular Voltage Source Inverters with Coupled Reactors
    • Krzysztof Szwarc
    • Paweł Szczepankowski
    • Janusz Nieznański
    • Cezary Swinarski
    • Aleksandr Usoltsev
    • Ryszard Strzelecki
    2020 Pełny tekst ENERGIES

    This paper proposes and discusses a concept of a hybrid modulation for the control of modular voltage source inverters with coupled reactors. The use of coupled reactors as the integrating elements leads to significant reduction in the size and weight of the circuit. The proposed modulation combines novel coarsely quantized pulse amplitude modulation (CQ-PAM) and innovative space-vector pulse width modulation (SVPWM). The former enjoys very low transistor switching frequency and low harmonic elimination, while the latter ensures high resolution of amplitude control. The SVPWM is based on the use of barycentric coordinates. The feasibility of the proposed solution is verified by simulations and laboratory tests of a 12-pulse modular voltage source inverters with two-level and three-level component inverters.

  • Hybrid Multi-Criteria Method of Analyzing the Location of Distributed Renewable Energy Sources
    • Alicja Stoltmann
    2020 Pełny tekst ENERGIES

    This paper presents the development and the application of a hybrid multi-criteria method, the combination of the Analytic Hierarchy Process (AHP), and numerical taxonomy (NT),to support the decision making on the location of distributed renewable energy sources meetingvarious types of assessment criteria. Finding criteria weights, using the AHP method, eliminates thedisadvantage of NT—which, in current form, is defined by its extreme values. The NT method is less mathematically complicated than the AHP method, and thus, less time-consuming. The combination of methods was used to investigate: (1) Which location among these analyzed has the best chance of implementation considering the author's set of criteria to describe the proposed locations in detail; and (2) which detailed criterion has the greatest impact on achieving the main goal. The proposed universal set of criteria consists of five main criteria (technical, economic, social, environmental, and legal), under which twenty-eight detailed criteria are listed. The hybrid multicriteria methodology was used to rank the proposed set of four wind farm locations in terms of chances for investment implementation in the shortest possible time. The ranking of the location obtained with this method should be treated as an element supporting the decision-maker. The location for wind power plant with installed capacity 40 MW was found to be the most suitable, and the results showed that the main contributing factors are carbon avoidance rate and the impact of the investment on environmentally protected areas.

  • Hybrid P3HT: PCBM/GaN nanowire/Si cascade heterojunction for photovoltaic application
    • Giorgi Tchutchulashvili
    • Krzysztof P. Korona
    • Wojciech Mech
    • Sergij Chusnutdinow
    • Marta Sobanska
    • Kamil Klosek
    • Zbigniew R. Zytkiewicz
    • Wojciech Sadowski
    2020 Pełny tekst JOURNAL OF NANOPARTICLE RESEARCH

    Poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) are commonly used for the fabrication of organic photovoltaics (OPV). Efficiency limitations of OPVs could be circumvented by incorporation of inorganic nanostructures into organic blends. Again, integration of organic solar cells with well-developed silicon photovoltaic technology is ultimately desirable. In present work, GaN nanowires with diameters of 25-50 nm and two lengths (200 and 500 nm) have been grown using molecular beam epitaxy technique. Solar-grade monocrystalline silicon wafers were used as substrates for nanowire synthesis. GaN nanostructures were incorporated into P3HT:PCBM photoactive layer in order to facilitate charge transfer between P3HT:PCBM and Si. Samples with and without nanowires were compared. Addition of nanowires led to improvement in photovoltaic performance. Open circuit voltage has risen by 72% and short circuit current density – by 200%. Rs have decreased 50 times and PCE rose 20.7 times. Additional maxima could be observed in photocurrent spectrum corresponding to carriers being generated near GaN absorption edge. Moreover, External Quantum Efficiency pikes near GaN absorption edge, indicating the formation of current transfer channel via P3HT/GaN/Si cascade heterojunction. Mechanism explaining source of abovementioned improvement is proposed.

  • Hybrid Technique for the EM Scattering Analysis with the Use of Ring Domain Decomposition
    • Michał Baranowski
    • Sebastian Dziedziewicz
    • Rafał Lech
    • Piotr Kowalczyk
    2020

    A hybrid technique combining finite-element and mode-matching methods for the analysis of scattering problems in open space is presented here. The main idea is based on impedance matrix descriptions of the boundary surrounding the discrete computational domain and combine it with external field described analytically. The discrete analysis, which is the most time- and memory-consuming, is limited here only to the close proximity of the posts or fragments of post which geometry is complex. All the obtained results have been verified by comparison with simulations performed using alternative methods or commercial software.

  • Hybrid TiO2–Polyaniline Photocatalysts and their Application in Building Gypsum Plasters
    • Agnieszka Sulowska
    • Izabela Wysocka
    • Daniel Pelczarski
    • Jakub Karczewski
    • Anna Zielińska-Jurek
    2020 Pełny tekst Materials

    Hybrid materials of conjugated polymer and titanium(IV) oxide have attracted considerable attention concerning their potential benefits, including (i) ecient exploitation of visible light, (ii) a high adsorption capacity for organic contaminants, (iii) and eective charge carriers separation. The new class of the photocatalysts is promising for the removal of environmental pollutants in both aqueous and gaseous phases. For the first time, in this study, the polyaniline (PANI)–TiO2 hybrid composite was used for the degradation of phenol in water and toluene in the gas phase. Polyaniline–TiO2 was prepared by the in situ polymerization of aniline on the TiO2 surface. The obtained hybrid material was characterized by diuse reflectance spectroscopy (DR/UV-Vis), X-ray diraction (XRD), fast-Fourier transformation spectroscopy (FTIR), photoluminescence (PL) spectroscopy, microscopy analysis (SEM/TEM), and thermogravimetric analysis (TGA). An insight into the mechanism was shown based on the photodegradation analysis of charge carrier scavengers. Polyaniline is an ecient TiO2 photosensitizer for photodegradation in visible light ( > 420 nm). The trapping experiments revealed that mainly h+ and OH were the reactive oxygen species that were responsible for phenol degradation. Furthermore, the PANI–TiO2 hybrid nanocomposite was used in gypsum plaster to study the self-cleaning properties of the obtained building material. The eect of PANI–TiO2 content on the hydrophilic/hydrophobic properties and crystallographic structure of gypsum was studied. The obtained PANI–TiO2-modified gypsum plaster had improved photocatalytic activity in the reaction of toluene degradation under Vis light

  • Hybridization of valuation procedures as a medicine supporting the real estate market and sustainable land use development during the covid-19 pandemic and afterwards
    • Małgorzata Renigier-Biłozor
    • Sabina Źróbek
    • Marek Walacik
    • Artur Janowski
    2020 LAND USE POLICY

    Currently we are facing the pandemic situation that occur all over the world. Regardless the country or even the region, the negative consequences that are expected could be very big and the level of crisis is not predictable. This situation is the challenge for the real estate market as well. Due to this fact, the authors believe that there is the time when deep transformation of approaches, procedures and awareness related to valuation domain becomes. Today, due to the fact of the global COVID-19 and pandemic restrictions is the best time to implement the automated models and advanced technological solutions to the valuation world. The authors proposed the hybrid approach that is the way to reconcile the participants on the property market. Hybrid approach is understanding as the synergy in combining aspects of new (automated solutions) and traditional components that are developed in the agile mode system creation. The proposed solutions can be treated as a cure for some symptoms of the real estate market infection but also as a vaccine, which should to a large extent prevent restrictions and nuisance in real estate valuation in case of repeated infection.

  • Hybrid‐mode single‐slope ADC with improved linearity and reduced conversion time for CMOS image sensors
    • Miron Kłosowski
    2020 Pełny tekst INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS

    In the paper, a single‐slope analog‐to‐digital converter (ADC) for integrated CMOS image sensor applications with an improved technique of conversion has been proposed. The proposed hybrid‐mode ADC automatically uses one of the following conversion techniques: time based (i.e. PWM) or voltage based (i.e. single‐slope). During the ADC operation, the clock frequency and reference voltage are modified in order to reduce the conversion time and achieve the optimal linearity. Owing to this, the pixel using a photodiode working in the integration mode achieves a linear photoconversion characteristics (irradiance to digital number), and the conversion period, which is determined by the darkest parts of a scene, is reduced by an order of magnitude comparing with known ADC solutions. The proposed conversion technique has been validated with the ASIC prototype of a CMOS imager containing photosensors integrated with the ADCs. The ASIC was fabricated in standard 0.18 μm CMOS technology. A specialized measurement system has been used to optimize linearity in the hybrid‐mode conversion (integral nonlinearity below 2 LSB). The conversion period has been reduced 15 times compared with the standard technique. Measurements confirm functionality of the proposed approach, implemented within a small pixel area.

  • Hydration of Oxometallate Ions in Aqueous Solution
    • Maciej Śmiechowski
    • Ingmar Persson
    2020 Pełny tekst INORGANIC CHEMISTRY

    The strength of hydrogen bonding to and structure of hydrated oxometallate ions in aqueous solution have been studied by double difference infrared (DDIR) spectroscopy and large-angle X-ray scattering (LAXS), respectively. Anions are hydrated by accepting hydrogen bonds from the hydrating water molecules. The oxygen atom of the permanganate and perrhenate ions form weaker and longer hydrogen bonds to water than the hydrogen bonds in bulk water (i.e., they act as structure breakers), while the oxygen atoms of the chromate, dichromate, molybdate, tungstate, and hydrogenvanadate ions form hydrogen bonds stronger than those in bulk water (i.e., they act as structure makers). The oxometallate ions form one hydration shell distinguishable from bulk water as determined by DDIR spectroscopy and LAXS. The hydration of oxoanions results in X−O bond distances ca. 0.02 Å longer than those in unsolvated ions in the solid state not involved in strong bonding to counterions. The oxygens of oxoanions with a central atom from the second and third series in the periodic table and the hydrogenvanadate ion hydrogen bind three hydrating water molecules, while oxygens of oxoanions with a heavier central atom only form hydrogen bonds to two water molecules.

  • Hydrodynamic cavitation based advanced oxidation processes: Studies on specific effects of inorganic acids on the degradation effectiveness of organic pollutants
    • Michał Gągol
    • Elvana Cako
    • Kirill Fedorov
    • Reza Soltani
    • Andrzej Przyjazny
    • Grzegorz Boczkaj
    2020 Pełny tekst JOURNAL OF MOLECULAR LIQUIDS

    The use of cavitation in advanced oxidation processes (AOPs) to treat acidic effluents and process water has become a promising trend in the area of environmental protection. The pH value of effluents – often acidified using an inorganic acid, is one of the key parameters of optimization process. However, in the majority of cases the effect of kind of inorganic acid on the effectiveness of degradation is not studied. The present study describes the results of investigations on the use of hydrodynamic cavitation (HC) for the treatment of a model effluent containing 20 organic compounds, representing various groups of industrial pollutants. The effluent was acidified using three different mineral acids. It was demonstrated that the kind of acid used strongly affects the effectiveness of radical processes of oxidation of organic contaminants as well as formation of harmful secondary pollutants. One of important examples is a risk of formation of p-nitrotolune. Sulfuric acid was the only chemical used for acidification which caused effective treatment with lack of formation of monitored type of secondary pollutants. The best treatment effectiveness – during a 6-hour cavitation process - in most cases much above 80% along with 90% TOC removal was obtained in the case of sulfuric acid. Nitric acid provided lower effectiveness (above 60% for most of the compounds). The worst performance are reported for hydrochloric acid – below 50% of degradation for most of the compounds.

  • Hydrodynamic Model of the New Waterway through the Vistula Spit
    • Michał Szydłowski
    • Tomasz Kolerski
    2020 Pełny tekst Polish Maritime Research

    The decision to build a new waterway (strait) in the Polish part of the Vistula Spit was made in 2017. The new connection between the Gulf of Gdańsk and the Vistula Lagoon is planned as an artificial navigable channel with a lock and a small port. During storm surges and wind tides in the gulf or in the lagoon, sluicing will be re-quired for vessels to tackle the Vistula Spit. This procedure does not require significant water flow through the channel in normal conditions. However, in the case of a lock failure or in the case of controlled opening of the gate to increase water exchange in the lagoon or to reduce flood risk in the Vistula Lagoon, high flow rates may occur in the navigable channel and in the neighboring port basin. In order to investigate the hydraulic conditions in such extraordinary situations, numerical modeling of the hydrodynamics during water damming in the gulf or in the lagoon is performed. To analyse the hydrodynamics of the artificial connection between the sea and the lagoon during periods of high water stages, mathematical modeling is required. This paper presents the shallow water equations (SWE) model adapted to simulate the flow through the port basin and the navigable channel.

  • Hydrogen Embrittlement and Oxide Layer E ect in the Cathodically Charged Zircaloy-2
    • Grzegorz Gajowiec
    • Michał Bartmański
    • Beata Majkowska-Marzec
    • Andrzej Zieliński
    • Bartosz Chmiela
    • Marek Derezulko
    2020 Pełny tekst Materials

    The present paper is aimed at determining the less investigated effects of hydrogen uptake on the microstructure and the mechanical behavior of the oxidized Zircaloy-2 alloy. The specimens were oxidized and charged with hydrogen. The different oxidation temperatures and cathodic current densities were applied. The scanning electron microscopy, X-ray electron diffraction spectroscopy, hydrogen absorption assessment, tensile, and nanoindentation tests were performed. At low oxidation temperatures, an appearance of numerous hydrides and cracks, and a slight change of mechanical properties were noticed. At high-temperature oxidation, the oxide layer prevented the hydrogen deterioration of the alloy. For nonoxidized samples, charged at different current density, nanoindentation tests showed that both hardness and Young’s modulus revealed the minims at specific current value and the stepwise decrease in hardness during hydrogen desorption. The obtained results are explained by the barrier effect of the oxide layer against hydrogen uptake, softening due to the interaction of hydrogen and dislocations nucleated by indentation test, and hardening caused by the decomposition of hydrides. The last phenomena may appear together and result in hydrogen embrittlement in forms of simultaneous hydrogen-enhanced localized plasticity and delayed hydride cracking.

  • Hydrogen embrittlement of X2CrNiMoCuN25-6-3 super duplex stainless steel welded joints under cathodic protection
    • Aleksandra Świerczyńska
    • Dariusz Fydrych
    • Michał Landowski
    • Grzegorz Rogalski
    • Jerzy Łabanowski
    2020 CONSTRUCTION AND BUILDING MATERIALS

    The effect of cathodic polarization conditions on hydrogen degradation of X2CrNiMoCuN25-6-3 super duplex stainless steel welded joints, obtained using flux cored arc and submerged arc welding methods, was evaluated. Slow strain rate tensile tests of base material and welded specimens, ferrite content measurements, scanning electron microscopy observations, and statistical analysis were performed. It was found that hydrogenation of super duplex steel welded joints under the conditions of cathodic protection in artificial seawater environment leads to hydrogen embrittlement and that the weld area shows the highest degree of degradation. Welded joints made with higher heat input and under higher current density tend to cause an increase in the degradation of mechanical properties. A series of models to analyze the relationship between conditions and properties of material under extreme environmental conditions were successfully elaborated and evaluated.

  • Hydrophobic deep eutectic solvents in microextraction techniques–A review
    • Patrycja Makoś
    • Edyta Słupek
    • Jacek Gębicki
    2020 Pełny tekst MICROCHEMICAL JOURNAL

    Over the past decade, deep eutectic solvents (DES) have been widely studied and applied in sample preparation techniques. Until recently, most of the synthesized DES were hydrophilic, which prevented their use in the extraction of aqueous samples. However, after 2015 studies on the synthesis and application of hydrophobic deep eutectic solvents (HDES) has rapidly expanded. Due to unique properties of HDES i.e. density, viscosity, acidity or basicity, polarity and volatility, good extractabilities for various target analytes, which could be altered by careful selection of the hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) components, HDES are promising alternatives to the traditional organic solvents employed in sample preparation. Moreover, the possibility HDES synthesis of non-toxic ingredients, makes HDES meet all the standards of green analytical chemistry. Practical applications of HDES in sample preparation include conventional liquid-liquid extraction, and several types of liquid-phase microextraction, as well as solid phase extraction. The present review covers a comprehensive summarizing of available literature data on the most important physicochemical properties of HDES playing a key role in aqueous sample preparation methods, their limitations as well as challenges in this area, and a perspective of their future are described.

  • HYGRO-MAGNETIC VIBRATION OF THE SINGLE-WALLED CARBON NANOTUBE WITH NONLINEAR TEMPERATURE DISTRIBUTION BASED ON A MODIFIED BEAM THEORY AND NONLOCAL STRAIN GRADIENT MODEL
    • Jena Subrat Kumar
    • S. Chakraverty
    • Mohammad Malikan
    • Hamid M. Sedighi
    2020 Pełny tekst International Journal of Applied Mechanics

    In this study, vibration analysis of single-walled carbon nanotube (SWCNT) has been carried out by using a refined beam theory, namely one variable shear deformation beam theory. This approach has one variable lesser than a contractual shear deformation theory such as first-order shear deformation theory (FSDT) and acts like classical beam approach but with considering shear deformations. The SWCNT has been placed in an axial or longitudinal magnetic field which is also exposed to both the hygroscopic as well as thermal environments. The thermal environment is considered as nonlinear thermal stress field based on the Murnaghan’s model whereas the hygroscopic environment is assumed as a linear stress field. The size effect of the SWCNT has been captured by both the nonlocal and gradient parameters by employing the Nonlocal Strain Gradient Theory (NSGT). Governing equation of motion of the proposed model has been developed by utilizing the extended Hamilton’s principle and the non- dimensional frequency parameters have been computed by incorporating the Navier’s approach for Hinged-Hinged (HH) boundary condition. The proposed model is validated with the existing model in special cases, by comparing the non- dimensional frequency parameters, displaying an excellent agreement. Further, a parametric study has been conducted to analyze the impact of nonlocal parameter, gradient parameter, thermal environment, hygroscopic environment, and magnetic field intensity on the non-dimensional frequency parameters. Also, results for some other theories like Classical Elasticity Theory (CET), Nonlocal Elasticity Theory (NET), and Strain Gradient Theory (SGT) have been presented along with the NSGT.

  • Hyperbolic Asynchronous Method of a Radio Navigation Technique
    • Ryszard Katulski
    • Jarosław Sadowski
    • Jacek Stefański
    • Wojciech Siwicki
    2020 Pełny tekst Applied Sciences-Basel

    Humans have always wanted to determine position in an unknown environment. At the beginning methods were simple. They were based on the observation of characteristic points, in the case of shipping additional observations of the coastline. Then came navigation based on astronomical methods (astronavigation). At the beginning of the XX-century a new way of determining the current location was developed. It has used radiowave signals. First came radio-beacons. Then ground-based systems came. Currently satellite systems are being used. At present, the most popular one is Global Positioning System (GPS). This system is fully controlled by the Department of Defense, and only the U.S. forces and their closest allies have been guaranteed accuracy offered by the system. Armies of other countries can only use the civilian version. This situation has engendered the need for an independent radiolocation system. This article describes the construction and operation of such a technology demonstrator that was developed at Gdansk University of Technology. The main advantage of the system is managing without the chain organization of the reference stations, which work now with each other asynchronously. This article demonstrates the functionality of such system. It also presents results and analysis of its effectiveness.

  • Hysteresis curves for some periodic and aperiodic perturbations in magnetosonic flow
    • Anna Perelomova
    2020 Pełny tekst PHYSICS OF PLASMAS

    A thermodynamic relation between perturbations of pressure and mass density in the magnetohydrodynamic flow is theoretically studied. Planar magnetohydrodynamic perturbations with the wave vector, which forms a constant angle with the equilibrium magnetic field, are under study. The theory considers thermal conduction of a plasma and the deviation from adiabaticity of a flow due to some kind of heating–cooling function. It also considers nonlinear distortion of a waveform and nonlinear excitation of the entropy mode in the field of intense magnetosonic perturbations. In some conditions, the total density of a plasma enlarges over a cycle of magnetosonic perturbations. These conditions depend on the type of magnetosonic waveform, heating–cooling function, thermal conduction, and equilibrium parameters of a plasma. They depend also on the angle between the wave vector and the magnetic field. The diagrams in the plane of total variation of pressure vs total variation of density indicate the nonlinear phenomena and irreversible processes in a flow. Harmonic perturbation and a bipolar impulse of pressure are considered as magnetosonic exciters of the entropy mode. Exemplary diagrams are plotted and discussed for these particular cases of exciters.

  • I, Robot: between angel and evil
    • Magdalena Popowska
    2020

    The boosting of most digital innovations within recent technology progress by artificial intelligence (AI) constitutes a growing topic of interest. Besides its technical aspects, increasing research activity may be observed in the domain of security challenges, and therefore of responsibility related to the controlled or hypothetically uncontrolled or autonomous emergence of AI solutions. Consequently, responsibility and ethics in the creation of AI-based systems, and thus also solutions (machine ethics), have been, especially recently, at the center of debates and regulatory activities. The present chapter, after a short introduction to the AI concept, next provides an overview of considerations on ethical aspects of AI’s wide deployment. It explores ethical considerations based on a literature review and provides some recommendations emanating both from regulatory effort at international level, and from the work of experts and scholars.

  • IATUL Seminar 2019 – ważne wydarzenie wpisujące się w rozwój działań Biblioteki Politechniki Gdańskiej na polu współpracy międzynarodowej.
    • Urszula Szybowska
    2020 Pełny tekst Pismo PG

    Celem IATUL Seminar 2019 (Organizing the Open Science Framework – Strategies and Legal Aspects) było podsumowanie aktualnego stanu otwartości w nauce w Polsce i na świecie. Problematyka podejmowana na konferencji skupiała się na przeglądzie polityki repozytoriów instytucjonalnych i usług związanych z zarządzaniem danymi badawczymi. Poruszano także zagadnienia dotyczące aspektów prawnych związanych ze zbieraniem, przechowywaniem i wykorzystywaniem danych badawczych. IATUL Seminar 2019 zostało zorganizowane przez Bibliotekę Politechniki Gdańskiej we współpracy z IATUL (International Association of University Libraries), międzynarodowym Stowarzyszeniem Bibliotek Uniwersyteckich.

  • ICT and social development. Conceptual considerations.
    • Ewa Lechman
    • Franciszek Kutrzeba
    • Kai Mustakoski
    2020

    This chapter is intended to provide basic ideas and concepts related to technology, technological progress and society. It explains how and why technology and society are interrelated, forming a dynamic, complex and interdependent evolutionary system. It introduces the terms Digital (ICT) Revolution and information and communication technologies (ICTs), showing elementary features of new technologies. The chapter explains why ICTs are labelled as general purpose technologies. Finally, it briefly discusses the potential channels through which information and communication technologies may affect society, emphasizing some potential benefits but also threats and challenges that society meets along with fast worldwide adoption of technologies.

  • Idea urbanistyczna Juliana Rummla i jej wpływ na międzywojenne plany Gdyni = The Urban Idea of Jukiab Rummel and Its Influence on the Interwar Plans of Gdynia
    • Maria Sołtysik
    2020

    Julian Rummel nie był ani architektem ani urbanistą. Był inżynierem budowy okrętów, działaczem gospodarczym, jednym w wielkich orędowników budowy portu i miasta Gdyni oraz współtwórcą polskiej polityki morskiej II Rzeczypospolitej. W połowie 1924 roku, kiedy rozpoczęto w Gdyni przebudowę otwartego zaledwie rok wcześniej Portu Tymczasowego na wielki, uniwersalny port stały, Julian Rummel był pierwszym którzy zwracali uwagę na pilną potrzebę budowy miasta przy powstającym porcie. W artykule napisanym w grudniu 1924 roku zaprezentował swoją wizję urbanistyczną nowego miasta i pomimo że koncepcja ta została zaprezentowana jedynie w formie opisowej, przedstawiała bardzo nowoczesne podejście do problematyki przestrzennej. Artykuł ten został zatytułowany Miasto Gdynia. Przyczynek do opracowania planu miasta. Autor odnosi się w nim do jednej z najważniejszych teorii urbanistycznych początków XX stulecia – do idei miasta-ogrodu, proponując zastosowanie jej do konstruowania planu ogólnego całego zespołu miejskiego Gdyni. Poza tym, Rummel w sposób bardzo sugestywny zarysował w tym artykule przyszły kształt Dzielnicy Reprezentacyjnej miasta, z dużym placem nadmorskim, Bazyliką Morską i ratuszem. Trzeba przy tym zaznaczyć, że naszkicowana przez niego w 1924 roku wizja została opublikowana półtora roku przed sporządzeniem pierwszych planów urbanistycznych Gdyni. W rezultacie też, okazała się ona stanowić inspirację dla wielu architektów-urbanistów projektujących miasto w okresie międzywojennym, a zwłaszcza dla projektantów planów z lat 1926 i 1938. W ich właśnie projektach znaleźć możemy w sposób najpełniejszy realizację wizji urbanistycznej Gdyni, przedstawionej przez Juliana Rummla już w pierwszej połowie lat dwudziestych.

  • Identification of Parameters Influencing the Accuracy of the Solution of the Nonlinear Muskingum Equation
    • Dariusz Gąsiorowski
    • Romuald Szymkiewicz
    2020 Pełny tekst WATER RESOURCES MANAGEMENT

    Two nonlinear versions of the Muskingum equation are considered. The difference between both equations relates to the exponent parameter. In the first version, commonly used in hydrology, this parameter is considered as free, while in the second version, it takes a value resulting from the kinematic wave theory. Consequently, the first version of the equation is dimensionally inconsistent, whereas the proposed second one is consistent. It is shown that the difference between the results provided by both versions of the nonlinear Muskingum equation depends on the longitudinal bed slope of a channel. For an increasing slope, when a propagating wave becomes more kinematic, the value of the exponent considered as the free parameter tends to its value resulting from the kinematic wave theory. Consequently, when the character of an open channel flow tends to a kinematic one, the dimensionally inconsistent version of the nonlinear Muskingum equation becomes a consistent one. The results of the numerical analysis suggest that apart from the parameters involved in the Muskingum equation, usually considered as free, the parameters of the numerical method of the solution (the number of reservoirs and the time step) should be considered also as free parameters. This conclusion results from the fundamental property of the Muskingum equation, relating to the numerical roots of the wave attenuation process. All numerical examples and tests relate to the solutions of the system of Saint Venant equations, considered as the benchmark.

  • Identification of Substrates of Cytoplasmic Peptidyl-Prolyl Cis/Trans Isomerases and Their Collective Essentiality in Escherichia Coli
    • Gracjana Klein-Raina
    • Paweł Wojtkiewicz
    • Daria Biernacka
    • Anna Stupak
    • Patrycja Gorzelak
    • Satish Raina
    2020 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Protein folding often requires molecular chaperones and folding catalysts, such as peptidyl-prolyl cis/trans isomerases (PPIs). The Escherichia coli cytoplasm contains six well-known PPIs, although a requirement of their PPIase activity, the identity of their substrates and relative enzymatic contribution is unknown. Thus, strains lacking all periplasmic and one of the cytoplasmic PPIs were constructed. Measurement of their PPIase activity revealed that PpiB is the major source of PPIase activity in the cytoplasm. Furthermore, viable Δ6ppi strains could be constructed only on minimal medium in the temperature range of 30–37 °C, but not on rich medium. To address the molecular basis of essentiality of PPIs, proteins that aggregate in their absence were identified. Next, wild-type and putative active site variants of FkpB, FklB, PpiB and PpiC were purified and in pull-down experiments substrates specific to each of these PPIs identified, revealing an overlap of some substrates. Substrates of PpiC were validated by immunoprecipitations using extracts from wild-type and PpiC-H81A strains carrying a 3xFLAG-tag appended to the C-terminal end of the ppiC gene on the chromosome. Using isothermal titration calorimetry, RpoE, RseA, S2, and AhpC were established as FkpB substrates and PpiC’s PPIase activity was shown to be required for interaction with AhpC.

  • Identification of the Agile Mindset and Its Comparison to the Competencies of Selected Agile Roles
    • Jakub Miler
    • Paulina Gaida
    2020

    In this paper we present the results of the identification and evalua-tion of the elements of an agile mindset as well as its comparison to the compe-tence models for the roles of Scrum Master, Product Owner and agile analyst. We have identified 70 unique agile mindset elements from literature and 5 in-terviews with experts. Based on an opinion survey among 52 agile practitioners we evaluated the importance of 26 selected elements of the agile mindset to the effectiveness of an agile team. The competence models contain 29 competen-cies of a Scrum Master, 16 competencies of a Product Owner and 40 competen-cies of an agile analyst, divided into behavioral, technical and contextual ones. We discuss which agile mindset elements are important to each agile role. This paper is an extended version of the paper titled “On the Agile Mindset of an Ef-fective Team – An Industrial Opinion Survey” presented at the 3nd International Conference on Lean and Agile Software Development LASD 2019 [28]

  • Il"valore aggiunto" delle biografie imprenditoriali
    • Luciano Segreto
    2020

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  • Image Representation for Cognitive Systems Using SOEKS and DDNA: A Case Study for PPE Compliance
    • Caterine Silva de Oliveira
    • Cesar Sanin
    • Edward Szczerbicki
    2020 Pełny tekst

    Cognitive Vision Systems have gained significant interest from academia and industry during the past few decade, and one of the main reasons behind this is the potential of such technologies to revolutionize human life as they intend to work under complex visual scenes, adapting to a comprehensive range of unforeseen changes, and exhibiting prospective behavior. The combination of these properties aims to mimic the human capabilities and create more intelligent and efficient environments. Nevertheless, preserving the environment such as humans do still remains a challenge in cognitive systems applications due to the complexity of such process. Experts believe the starting point towards real cognitive vision systems is to establish a representation which could integrate image/video modularization and virtualization, together with information from other sources (wearable sensors, machine signals, context, etc.) and capture its knowledge. In this paper we show through a case study how Decisional DNA (DDNA), a multi-domain knowledge structure that has the Set of Experience Knowledge Structure (SOEKS) as its basis can be utilized as a comprehensive embedded knowledge representation in a Cognitive Vision System for Hazard Control (CVP-HC). The proposed application aims to ensure that workers remain safe and compliant with Health and Safety policy for use of Personal Protective Equipment (PPE) and serves as a showcase to demonstrate the representation of visual and non-visual content together as an experiential knowledge in one single structure.

  • Immittance Studies of Bi6Fe2Ti3O18 Ceramics
    • Agata Lisińska-Czekaj
    • Dionizy Czekaj
    • Barbara Garbarz-Glos
    • Wojciech Bąk
    2020 Pełny tekst Materials

    Results of studies focusing on the electric behavior of Bi6Fe2Ti3O18 (BFTO) ceramics are reported. BFTO ceramics were fabricated by solid state reaction methods. The simple oxides Bi2O3, TiO2, and Fe2O3 were used as starting materials. Immittance spectroscopy was chosen as a method to characterize electric and dielectric properties of polycrystalline ceramics. The experimental data were measured in the frequency range D = (101–107) Hz and the temperature range DT = (120–200) C. Analysis of immittance data was performed in terms of complex impedance, electric modulus function, and conductivity. The activation energy corresponding to a non-Debye type of relaxation was found to be EA = 0.573 eV, whereas the activation energy of conductivity relaxation frequency was found to be EA = 0.570 eV. An assumption of a hopping conductivity mechanism for BFTO ceramics was studied by ‘universal’ Jonscher’s law. A value of the exponents was found to be within the “Jonscher’s range” (0.54 n 0.72). The dc-conductivity was extracted from the measurements. Activation energy for dc-conductivity was calculated to be EDC = 0.78 eV, whereas the dc hopping activation energy was found to be EH = 0.63 eV. The obtained results were discussed in terms of the jump relaxation model.

  • Immunosuppressive properties of amino acid and peptide derivatives of mycophenolic acid
    • Agnieszka Siebert
    • Grzegorz Cholewiński
    • Piotr Trzonkowski
    • Janusz Rachoń
    2020 Pełny tekst EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY

    Mycophenolic acid (MPA) was coupled with amino acids and biologically active peptides including derivatives of tuftsin to modify its immunosuppressive properties. Both amino acid unit in the case of simple MPA amides and modifications within peptide moiety of MPA - tuftsin conjugates influenced the observed activity. Antiproliferative potential of the obtained conjugates was investigated in vitro and MPA amides with threonine methyl ester and conjugate of MPA with retro-tuftisin occurred to be more selective against PBMC in comparison to parent MPA. Both amino acid and peptide derivatives of MPA acted as inosine-5'-monophosphate dehydrogenase (IMPDH) inhibitors.

  • Impact of Spatial Noise Correlation on Bearing Accuracy in DIFAR Systems
    • Mariusz Rudnicki
    • Jacek Marszal
    • Roman Salamon
    2020 Pełny tekst Archives of Acoustics

    DIFAR type underwater passive systems are one of the more commonly used tools for detecting submarines. At the design stage, which usually uses computer simulations, it is necessary to generate acoustic noise of the sea. It has been shown that correlating noise significantly reduces these errors compared to the assumption that noise is uncorrelated. In addition, bearing errors have been shown to be the same in systems with a commonly used antenna containing five hydrophones, as in a system without a central hydrophone, which may be useful in some DIFAR system design solutions.

  • Impact of the anion and chalcogen on the crystal structure and properties of 4,6-dimethyl-2-pyrimido(thio)nium halides
    • Andrzej Okuniewski
    • Damian Rosiak
    • Jarosław Chojnacki
    2020 Pełny tekst Acta Crystallographica Section C-Structural Chemistry

    By the reaction of urea or thiourea, acetylacetone and hydrogen halide (HF, HBr or HI), we have obtained seven new 4,6-dimethyl-2-pyrimido(thio)nium salts, which were characterized by single-crystal X-ray diffraction, namely, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium bifluoride, C₆H₉N₂O⁺·HF₂⁻ or (dmpH)F₂H, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium bromide, C₆H₉N₂O⁺·Br⁻ or (dmpH)Br, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium iodide, C₆H₉N₂O⁺·I⁻ or (dmpH)I, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium iodide–urea (1/1), C₆H₉N₂O⁺·I⁻·CH₄N₂O or (dmpH)I·ur, 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium bifluoride–thiourea (1/1), C₆H₉N₂S⁺·HF₂⁻·CH₄N₂S or (dmptH)F₂H·tu, 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium bromide, C₆H₉N₂S⁺·Br⁻ or (dmptH)Br, and 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium iodide, C₆H₉N₂S⁺·I⁻ or (dmptH)I. Three HCl derivatives were described previously in the literature, namely, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium chloride, (dmpH)Cl, 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium chloride monohydrate, (dmptH)Cl·H₂O, and 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium chloride–thiourea (1/1), (dmptH)Cl·tu. Structural analysis shows that in 9 out of 10 of these compounds, the ions form one-dimensional chains or ribbons stabilized by hydrogen bonds. Only in one compound are parallel planes present. In all the structures, there are charge-assisted N⁺—H∙∙∙X⁻ hydrogen bonds, as well as weaker Cₐᵣ⁺—H∙∙∙X⁻ and π⁺∙∙∙X⁻ interactions. The structures can be divided into five types according to their hydrogen-bond patterns. All the compounds undergo thermal decomposition at relatively high temperatures (150–300°C) without melting. Four oxopyrimidinium salts containing a π⁺∙∙∙X⁻∙∙∙π⁺ sandwich-like structural motif exhibit luminescent properties.

  • Impact of the trap–assisted recombination in the perovskite solar cells
    • Damian Głowienka
    • Dong Zhang
    • Mehrdad Najafi
    • Francesco Di Giacomo
    • Jędrzej Szmytkowski
    • Yulia Galagan
    2020 Pełny tekst

    To achieve the highest performance using perovskite solar cells it is necessary to understand all the dominant mechanisms which affect the operation of solar cell. Here, we have investigated the bulk and interface trap–assisted recombination processes in the solar cells with p–i–n architecture. These studies are based on the numerical and experimental methods to get better understanding of these physical processes. The following results are useful for optimization of the performance of perovskite solar cells.

  • Impact performance of novel multi-layered prepacked aggregate fibrous composites under compression and bending
    • G. Murali
    • Sallal R. Abid
    • Y.H. Mugahed Amran
    • Hakim Abdelgader
    • Roman Fediuk
    • Arikatla Susrutha
    • K. Poonguzhali
    2020 Structures

    Multi-layered Prepacked aggregate fibrous composite (MLPAFC) is a new type of concrete, which is prepared in two subsequent stages of aggregate-fibre skeleton prepacking and cementitious grouting. In this study, ten MLPAFC mixtures were prepared in three subsequent layers incorporating different contents of four different types of steel fibres. Long and short hooked-end and crimped steel fibers were adopted with 3.0 and 1.5% dosages for the outer and interior layers, respectively. In-between the three MLPAFC layers, two layers of Glass Fiber Mesh (GFM) were inserted in five of the ten mixtures. The impact response of the MLPAFC mixtures was evaluated using two test methods. In the first, the ACI 544-2R repeated free-falling weight test was followed using disk specimens, while flexural free-falling weight on prism specimens was the second adopted impact test. Moreover, Weibull distribution was used to statistically analyse the discrepancies of the obtained experimental impact records. The impact tests results revealed that MLPAFC can absorb significantly high energy under falling weight impact due to its structure and the dual crack arresting activity of both steel fibers and GFM. The cracking number of impacts of MLPAFC cylindrical specimens without GFM was increased by approximately 530–870% compared reference specimens, while increment percentages reaching 1350% were recorded at failure stage. The impact resistance of MLPAFC prisms under flexural impact was noticeably improved, yet with lower percentages than cylindrical specimens. The insertion of intermediate GFMs let to additional developments in the impact strength of both cylindrical and prism specimens.

  • Impact response of two-layered grouted aggregate fibrous concretecomposite under falling mass impact
    • M. K. Haridharan
    • S. Matheswarana
    • G. Murali
    • Sallal R. Abid
    • Roman Fediuk
    • Y.h. Mugahed Amran
    • Hakim Abdelgader
    2020 CONSTRUCTION AND BUILDING MATERIALS

    Two-layered Grouted Aggregates Fibrous Concrete Composite (TGAFCC) is a new category concrete which became popular recently and attracted the attention of researchers globally. Recent studies indicated that TGAFCC has notable improvement in mechanical properties, which has been sufficiently documented. However, the impact behaviour of TGAFCC when combined with Glass Fibre Mesh (GFM) and Textile Fibre Mesh (TFM) is still unexplored. The research objective is to study the effect of GFM and TFM insertion in TGAFCC against the drop hammer impact. Twenty one TGAFCC mixtures were prepared and divided into two series; non-fibrous concrete and fibrous concrete. The combined action of GFM and TFM of various diameters were inserted between the two layers and tested experimentally against drop mass impact. Additionally, all fibrous specimens were reinforced with a constant 3% dosage of 5D hooked end fibre. All specimens were tested under repeated drop mass impact as per ACI Committee 544. The impacts number or number of blows till the first visible crack and failure, impact energy at the first visible crack and failure, impact ductility index and cracking configuration were examined. Besides, Weibull distribution was used to examine the variations in the test results, where impact numbers were presented using the reliability function. The research findings indicate that inserting GFM and TFM between the two layers combined with 5D hooked end steel fibres, provided high impact resistance, higher absorbed energy and prolonged failure duration. Increasing the diameters of the GFM and TFM insertions, in both non-fibrous and fibrous concrete resulted in increasing the impact numbers till the first visible crack and failure. The experimental findings confirm that the major contribution of impact resistance comes from the 5D hooked end steel fibres, while the share of the intermediate meshes was significantly lower.

  • Implant system for treatment of the orbital floor defects of blowout fractures in the maxillofacial region using polypropylene yarn and bioactive bone cement
    • Marcin Wekwejt
    • Damroka Etmańska
    • Aleksandra Halman
    • Anna Pałubicka
    • Beata Świeczko-Żurek
    • Grzegorz Gajowiec
    2020 Pełny tekst JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS

    Fractures in the craniofacial region are a serious problem in terms of treatment. The most reasonable solution is the use of individual implants dedicated to a specific patient. The aim of this study was to develop the implant system specifically for treatment of the orbital floor defects of blowout fractures of maxillofacial region, using polypropylene yarn and bone cement. Three types of bone cement were used to fix the polypropylene yarn: unmodified, antibiotic‐loaded, and modified with nanometals. The following research was carried out: selection of cement production parameters, assessment of the curing time, measurement of polymerization temperature, an analysis of microstructure and surface topography, evaluation of wettability, measurement of microhardness, and studies of bactericidal effectiveness. The research confirms the possibility of using bone cement and polypropylene yarn for an individual implant, dedicated to the fractures treatment in the maxillofacial region. Moreover, the bactericidal properties of the proposed modifications for bone cement have been verified; hence, bioactive cements are recommended for use in the case of infectious complications.

  • Implementation of advanced micropollutants removal technologies in wastewater treatment plants (WWTPs) - Examples and challenges based on selected EU countries
    • Klaudia Kosek
    • Aneta Łuczkiewicz
    • Sylwia Fudala-Książek
    • Katarzyna Jankowska
    • Małgorzata Szopińska
    • Ola Svahn
    • Jens Tränckner
    • Alena Kaiser
    • Valdas Langas
    • Erland Björklund
    2020 Pełny tekst ENVIRONMENTAL SCIENCE & POLICY

    The accumulation of micropollutants (MPs) and their increasing concentration in the aquatic environment are an emerging issue for water quality in the world. The complex web of exposure pathways, as well as the variety in the chemical structure and potency of MPs, represents enormous challenges for researchers and policy initiatives. In order to manage MPs, it has to be decided which of them have to be reduced and to what extent, where in the water cycle this would be the most efficient and which technical means that should be applied to be sustainable. All of these aspects require a knowledge of MPs abundance, properties, fate and impact in the environment, which is essentially determined by two related features: the sources and the physico-chemical characteristics of MPs. Micropollutants including pharmaceuticals, antibiotics and hormones can enter the aquatic environment through both diffuse and point sources, but in urbanised regions wastewater treatment plants (WWTPs) play a crucial role in their dissemination. Conventional WWTPs are effective in removal of macropollutants (e.g. nutrients, suspended solids and some trace elements), while MPs may go through the treatment unchanged or be removed at different rates. Most of the EU countries are convinced that the presence of MPs in the environment poses a serious problem, particularly in highly populated regions where surface water resources serve as a source of potable water. Presently, various technical solutions are available and have been proven possible to integrate with existing treatment processes in an expedient manner. The solutions that have been evaluated are mainly based on ozonation and/or activated carbon treatment technologies which may definitely be considered the most effective compared to the costs incurred.

  • Implementation of Hermite-Ritz method and Navier’s Technique for Vibration of Functionally Graded Porous Nanobeam Embedded in Winkler-Pasternak Elastic Foundation Using bi-Helmholtz type of nonlocal elasticity
    • Subrat Kumar Jena
    • S. Chakraverty
    • Mohammad Malikan
    • Hamid M. Sedighi
    2020 Pełny tekst Journal of Mechanics of Materials and Structures

    Present study is devoted to investigating the vibration characteristics of Functionally Graded (FG) porous nanobeam embedded in an elastic substrate of Winkler-Pasternak type. Classical beam theory (CBT) or Euler-Bernoulli beam theory (EBT) has been incorporated to address the displacement of the FG nanobeam. Bi-Helmholtz type of nonlocal elasticity is being used to capture the small scale effect of the FG nanobeam. Further, the nanobeam is assumed to have porosity, distributed evenly along the thickness throughout the cross-section. Young’s modulus and mass density of the nanobeam are considered to vary along the thickness from ceramic to metal constituents in accordance with power-law exponent model. A numerically efficient method, namely the Hermite-Ritz method, is incorporated to compute the natural frequencies of Hinged-Hinged (HH), Clamped-Hinged (CH), and Clamped-Clamped (CC) boundary conditions. A closed-form solution is also obtained for Hinged-Hinged (HH) boundary condition by employing Navier’s technique. The advantages of using Hermite polynomials as shape functions are orthogonality, a large domain that makes the method more computationally efficient and avoids ill-conditioning for higher values of polynomials. Additionally, the present results are validated with other existing results in special cases demonstrating excellent agreement. A comprehensive study has been carried out to justify the effectiveness or convergence of the present model or method. Likewise, impacts of various scaling parameters such as Helmholtz and bi-Helmholtz types of nonlocal elasticity, porosity volume fraction index, power-law exponent, and elastic foundation on frequency parameters have been investigated.

  • Implementation of spatial/polarization diversity for improved-performance circularly polarized multiple-input-multiple-output ultra-wideband antenna
    • Ubaid Ullah
    • Ismail Mabrouk
    • Sławomir Kozieł
    • Muath Al-hasan
    2020 Pełny tekst IEEE Access

    In this paper, spatial and polarization diversities are simultaneously implemented in an ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna to reduce the correlation between the parallel-placed radiators. The keystone of the antenna is systematically modified coplanar ground planes that enable excitation of circular polarization (CP). To realize one sense of circular polarization as well as ultra-wideband operation, an extended rectangular slot is etched on the left-hand-side of the coplanar waveguide (CPW) feed. This is combined with the asymmetrical ground plane geometry on the right-hand-side of the feeding line. The current flowing on the slotted ground plane forms a quasi-loop and generates CP, whereas the combination of the vertical current on the feedline and the horizontal current on the asymmetric ground plane adds to the axial ratio (AR) bandwidth. To implement the MIMO design with polarization and spatial diversity, the position of the coplanar ground planes is switched with respect to the feedline, and placed in a parallel formation with the edge-to-edge distance of 0.29λ0 . All geometrical parameters are optimized at the full-wave level of description before prototyping and experimental characterization. Simulation and measured results indicate that the proposed MIMO antenna features approximately 82% impedance bandwidth from 2.9 GHz to 7.1 GHz and 68.5% (3.1 GHz- 6.35 GHz) AR bandwidth. Moreover, the peak envelop correlation coefficient (ECC) is below 0.003, which corresponds to almost no correlation between the radiators. The antenna can be operated with either bidirectional or unidirectional characteristics, covering multiple commercial application bands including WLAN and WiMax.

  • Implementation Of The Innovative Radiolocalization System VCS-MLAT (Voice Communication System Multilateration)
    • Szymon Wiszniewski
    • Olga Błaszkiewicz
    • Alicja Olejniczak
    • Jarosław Sadowski
    • Jacek Stefański
    2020

    In the article the concept of the radiolocalization subsystem of the VHF communication for aviation VCS-MLAT (Voice Communication System – Multilateration) is presented. The distributed localization system can estimate the position of the aircraft using the audio signals from aircraft transmitters in the VHF band (118-136 MHz). This paper shows initial verification of the possibility to use voice airband communication to estimate the position of the aircraft. Main assumptions of the project and the structure of the localization modules (ground receiver stations) are also presented.