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  • Simple sufficient condition for subspace to be completely or genuinely entangled
    • Maciej Demianowicz
    • Grzegorz Rajchel-Mieldzioć
    • Remigiusz Augusiak
    2021 Pełny tekst NEW JOURNAL OF PHYSICS

    We introduce a simple sufficient criterion, which allows one to tell whether a subspace of a bipartite or multipartite Hilbert space is entangled. The main ingredient of our criterion is a bound on the minimal entanglement of a subspace in terms of entanglement of vectors spanning that subspace expressed for geometrical measures of entanglement. The criterion is applicable to both completely and genuinely entangled subspaces. We explore its usefulness in several important scenarios. Further, an entanglement criterion for mixed states following directly from the condition is stated. As an auxiliary result we provide a formula for the generalized geometric measure of entanglement of the $d$--level Dicke states.

  • Simplified approach to assess the dynamic response of a container ship subjected to bow slamming load
    • Krzysztof Wołoszyk
    • Marian Bogdaniuk
    2021 Pełny tekst

    Simplified approach to assess the dynamic response of a container ship subjected to the bow slamming load, resulting in a transient vibratory response, typically called a 'whip-ping', is presented. The accurate numerical modelling is very complex and involves cou-pling of the hydrodynamic and structural solution at every time step, leading to huge com-putational and workload cost. Thus, the one-way coupling methodology is adopted, and hydrodynamic loads are derived using linear strip theory in the first step and applied to the FE beam model. Structural response is obtained in the time domain using an explicit dy-namic solver. Extreme bending moment is derived and compared with the normative val-ues of the wave-induced bending moment. Comparing to more accurate methods, the pre-sented approach seems to overestimate the bending moment and leads to a conservative design. Thus, it may be used in the early stages of the design, where fast and reliable methods are essential.

  • Simplified Method of Modelling Behaviour of Ship in Waves with Partially Flooded Compartments
    • Peter Szulczewski
    2021 Pełny tekst Transactions on Maritime Science-ToMS

    This paper contains a description of a numerical model for calculating behaviour of ships in waves. There are many models available, but the one described here can be characterised with a set of parameters that have a decisive impact on the final values of roll motion amplitude and frequency. In this paper, it is shown how a fitting of a standard-shape hull characterised by certain readily available parameters affects the final roll and frequency of the motion. In addition, calculations for a flooded tank were made, and a range of results for the maximum dynamic heeling forces from this tank is shown. This calculation can further be verified for a range of hull dimensions and geometries to present a viable method to the industry.

  • Simulation investigation of perovskite-based solar cells
    • Maciej Łuszczek
    • Grzegorz Łuszczek
    • Dariusz Świsulski
    2021 Pełny tekst Przegląd Elektrotechniczny

    Three models of thin-layer lead-halide perovskite solar cells with different electron-transport layers (TiO2,SnO2,ZnO) were investigatedby the simulation method. The perovskite layer thickness was optimized for all the systems. The analysis of the standard photovoltaic cell performanceparameters at various operating temperatures was performed. The best performance was achieved for the system with theSnO2conductive layer.

  • Simulation of the number of storm overflows considering changes in precipitation dynamics and the urbanisation of the catchment area: a probabilistic approach
    • Bartosz Szeląg
    • Roman Suligowski
    • Jakub Drewnowski
    • Francesco De Paola
    • Francisco-Jesus Fernandez-Morales
    • Łukasz Bąk
    2021 Pełny tekst JOURNAL OF HYDROLOGY

    This paper presents a probabilistic methodology that allows the study of the interactions between changes in rainfall dynamics and impervious areas in urban catchment on a long- and short-term basis. The proposed probabilistic model predict future storm overflows while taking into account the dynamics of changes in impervious areas and rainfall. In this model, a logistic regression method was used to simulate overflow resulting from precipitation events based on average rainfall intensity and impervious area. The adopted approach is universal (as it can be used in other urban catchments) and is a significant simplification of classic solutions; a hydrodynamic model is used to analyse the operation of the overflow. For the rainfall simulations, a rainfall generator based on the Monte Carlo method was used. In this method, a modification that allows the simulation of changes taking place in rainfall dynamics, including the effects of climate change, was introduced. This method provides the opportunity to expand and modify probabilistic models in which outflow from the catchment is modelled to predict the functioning of reservoirs and to design sewer networks that have the ability to deal with future rainfall dynamics, including moderate, strong, and violent downpours according to the Sumner scale. To verify the simulation results with a probabilistic model, an innovative concept using a hydrodynamic model was considered. This verification considers the changes in the impervious area in the period covered by the simulations and is limited using standard calculation procedures. In practice, the model presented in this work creates opportunities for defining the concept of sustainable development in urban catchments while taking into account the factors mentioned above. From the perspective of landscaping, this is important because it creates the opportunity to limit the impacts of climate change and area urbanization on the receiving waters.

  • Simulation Studies of Control Systems for Doubly Fed Induction Generator Supplied by the Current Source Converter
    • Paweł Kroplewski
    • Marcin Morawiec
    • Andrzej Jąderko
    • Charles Odeh
    2021 Pełny tekst ENERGIES

    The control system for a Doubly Fed Induction Generator (DFIG) supplied by a grid-connected Current Source Converter (CSC) is presented in this paper. Nonlinear transformation of DFIG model to the multi-scalar form is proposed. The nonlinear control strategy of active and reactive power of DFIG is realized by feedback linearization. In the proposed control scheme, the DFIG model and CSI parameters are included. Two Proportional-Integral (PI) controllers are dedicated for the control of the respective active and reactive powers. The control variables are the dc-link input voltage vector and the angular speed of the inverter output current. The proposed control approach is characterized by satisfactional dynamics and provides enhanced quality of the power transferred to the grid. In the simulation, evaluation of the characteristic operating states of the generator system, correctness of the feedback linearization and the dynamics of active and reactive power control loops are studied. Simulation results are adequately provided.

  • Simulator for Performance Evaluation of ASON/GMPLS Network
    • Sylwester Kaczmarek
    • Magdalena Młynarczuk
    2021 Pełny tekst IEEE Access

    The hierarchical control plane network architecture of Automatically Switched Optical Network with utilization of Generalized Multi-Protocol Label Switching protocols is compliant to next generation networks requirements and can supply connections with required quality of service, even with incomplete domain information. Considering connection control, connection management and network management, the controllers of this architecture could perform the same operations on the transport plane resources and could support control functions for Software Defined Networking controllers, which are considered as the future networking solutions. Therefore, it is very important to determine factors that have an influence on service control and resource management. One of the tools for achieving this goal is computer simulation. The paper proposes a simulator for the hierarchical control plane networks in an open source OMNeT++ environment, in order to evaluate network architecture performance for different network structures and traffic parameters. To demonstrate simulator capabilities, examples of typical simulations performance results for Polish and European network structures are presented and discussed. Performance metrics which have been used to evaluate the performance of this architecture are: mean values of Call Set-up Time, Connection Set-up Time, Call Release Time, Connection Release Time, loss probability for inter-domain connection requests and loss probability for low and high priority requests. General remarks concerned with presented simulator are also provided.

  • Simultaneous opto-electrochemical monitoring of carbamazepine and its electro-oxidation by-products in wastewater
    • Mattia Pierpaoli
    • Anna Dettlaff
    • Małgorzata Szopińska
    • Katarzyna Karpienko
    • Maciej Wróbel
    • Aneta Łuczkiewicz
    • Sylwia Fudala-Książek
    • Robert Bogdanowicz
    2021 Pełny tekst JOURNAL OF HAZARDOUS MATERIALS

    The growing human impact on aquatic environments, due to the extensive use of pharmaceuticals and the release of persistent pollutants, makes it necessary to implement new widespread methods for the characterisation and quantification of such contaminants and relative degradation products. Carbamazepine, 5H-dibenzo[b,f]azepine-5-carboxamide, (CBZ) is a widely used anti-epileptic drug, characterised by its limited removal by conventional wastewater treatments and high persistency in the environment. In this work, CBZ detection and quantification was performed in phosphate buffer as well as in samples of complex matrix like landfill leachates and treated wastewater originating from a medical facility, and simultaneously by optical and electrochemical methods using a novel transparent carbon-based nanostructured electrode. Coupling electrochemical (differential pulse voltammetry) with optical (UV-visible spectroscopy) methods, it has been possible to reach a limit of detection (LOD) for CBZ detection at the level of 4.7 μM for the electrochemical method, 10.3 μM for the spectroscopic method, and 3.6 μM for the opto-electrochemical method. Raman spectroscopy and ultra-high performance liquid chromatography coupled with tandem mass spectrometry techniques were employed to support and validate the combined technique. The novel developed technique showed high selectivity to carbamazepine and its by-products, even in environmental samples. Thus, this environmentally friendly, fast and accurate detection method is believed to be successfully implemented in the investigation of other pharmaceutical and chemical contaminates of concern.

  • Simultaneous Removal of Al, Cu and Zn Ions from Aqueous Solutions Using Ion and Precipitate Flotation Methods
    • Piotr Rybarczyk
    • Bożenna Kawalec-Pietrenko
    2021 Pełny tekst Processes

    This paper presents the results of investigations concerning the simultaneous removal of Al(III), Cu(II), and Zn(II) from dilute aqueous solutions using ion and precipitate flotation methods. The effects of initial solution pH, surface active substance concentration, and the gas velocity on the flotations’ efficiency and course are studied. Experimental results are discussed in terms of physicochemical aspects related to aqueous solutions of metal salts. The results indicate that satisfying simultaneous flotations of aluminum, copper and zinc species are observed if the pH value ranges between 7.0 and 9.0. It was found that an increase in collector concentration results in a decrease in the flotation rate constants. An increase in the gas velocity results in an increase in the ion and precipitate flotation rates.

  • Skuteczność klasyfikacji gatunków muzycznych za pomocą sieci neuronowej w zależności od typu danych wejściowych
    • Maciej Blaszke
    • Damian Koszewski
    • Bożena Kostek
    2021

    Rozpoznawanie gatunku muzycznego jest jednym z podstawowych elementów inteligentnych systemów tworzenia automatycznych list muzyki. Platformy strumieniowe oferujące taką usługę wymagają rozwiązań, które umożliwią jak najdokładniej określić przynależność utworu do gatunku muzycznego. Zgodnie z aktualnym stanem wiedzy – najskuteczniejszym klasyfikatorem są sztuczne sieci neuronowe (w tym w wersji uczenia głębokiego), dla których wejście może stanowić spektrogram (postać 2D wektora wejściowego), współczynniki MFCC czy wektor parametrów. We wcześniejszych pracach autorzy opisali opracowaną przez siebie sztuczną sieć neuronową, która z 5-procentowym błędem pozwoliła wyznaczyć zestaw deskryptorów standardu MPEG-7. Mogą one zostać wykorzystane między innymi jako dane wejściowe do klasyfikatora gatunku muzycznego. W rozdziale zaprezentowano porównanie skuteczności klasyfikatora wykorzystującego architekturę głęboką w zależności od typu danych wejściowych, takich jak: sygnał w postaci czasowej, spektrogram, MFCC, wektor parametrów oraz deskryptory niskopoziomowe standardu MPEG-7 zarówno występujące w bazie danych, jak i te obliczone z wykorzystaniem sieci neuronowej.

  • SMAKI ZIEMI ZABORSKIEJ. dziedzictwo przyrodnicze i kulturowe
    • Agnieszka Kurkowska
    2021

    Seminarium naukow „Smaki ziemi zaborskiej. Dziedzictwo przyrodnicze i kulturowe” współorganizowane było przez Wydział Architektury Politechniki Gdańskiej oraz Wielewski Dom Kultury im. Hieronima Derdowskiego/ Muzeum Ziemi Zaborskiej. Partnerami były Pomorski Zespół Parków Krajobrazowych, Centrum Edukacji i Informacji Ekologicznej w Gdańsku, Zaborski Park Krajobrazowy, Zaborskie Towarzystwo Naukowe, Muzeum Historyczno-Etnograficzne im. Juliusza Rydzkowskiego w Chojnicach, Lasy Państwowe: Nadleśnictwo Czersk, Nadleśnictwo Kościerzyna. Patronatu wydarzeniu udzielili Pomorska Okręgowa Izba Architektów RP oraz Oddział Wybrzeże Stowarzyszenia Architektów Polskich. Prelegenci odnieśli się do dziedzictwa wspólnoty, historii Zaborów, haftu zaborskiego, czasoprzestrzeni Anny Łajming w literackich zaborskich wędrówkach, wysmakowanego krajobrazu przyrodniczego i kulturowego wsi zaborskiej, zióła i związanych z nimi tradycji, obrazu domu zaborskiego w literaturze, smaku tajemniczych podań zaborskich, kaszubskiego domu tradycyjnego i współczesnego, zaborskiego lasu i smaków, które stamtąd pochodzą.

  • Small Urban Hacks - Big Impact! Tackling major urban challenges through acupunctural smallness
    • Dorota Kamrowska-Załuska
    • David Calas
    • Edeltraud Haselsteiner,
    • Marielle Ferreira SILVA
    • Aránzazu Galán González
    • Emanuela Giancola
    • Mihaela Hărmănescu
    • Silvia Soutullo Castro
    2021

    Small urban hacks, acupunctural action and process-oriented planning approaches might appear to address quite a socio-romantic attitude towards our urban environments. In this chapter, our aim is to remedy such a biased view, demonstrating the impact and potential of smallness in the context of major urban challenges. Small urban hacks and their multi-faceted and creativity-driven approaches of small is beautiful are selected from all over Europe to investigate the rigidity of the existing urban fabric. Small actions are reflected in a quantitative and qualitative way, analyzing and critically dissecting their impact, civic acceptance and efforts to achieve a resilient future urban spirit. This meticulous inspection reframes the urban acupuncture standpoint, outlining the possibility for reconciliation between both former and current planning credos in view of present and upcoming urban threats.

  • Smart Approach for Glioma Segmentation in Magnetic Resonance Imaging using Modified Convolutional Network Architecture (U-NET)
    • Nosheen Sohail
    • Syed M. Anwar
    • Farhat Majeed
    • Edward Szczerbicki
    2021 Pełny tekst CYBERNETICS AND SYSTEMS

    Segmentation of a brain tumor from magnetic resonance multimodal images is a challenging task in the field of medical imaging. The vast diversity in potential target regions, appearance and multifarious intensity threshold levels of various tumor types are few of the major factors that affect segmentation results. An accurate diagnosis and its treatment demand strict delineation of the tumor affected tissues. Herein, we focus on a smart, automated, and robust segmentation approach for brain tumor using a modified 3D U-Net architecture. The pre-operative multimodal 3D-MRI scans of High-Grade Glioma (HGG) and Low-Grade Glioma (LGG) are used as data. Our proposed approach solves the problem of memory and system resource constraints by robustly applying dense network training on image patches of 3D volumes. It improves the border region artifact detection by applying convolutions at an appropriate phase in the proposed neural network. Multi-class imbalance data are handled by using Categorical Cross Entropy (CCE) loss developed by combining the Weighted Cross Entropy (WCE) with Weighted Multi-class Dice Loss (WMDL) functions, which enables the network to perform smart segmentation of the smaller tumorous regions. The proposed approach is tested and evaluated for the challenge datasets of multimodal MRI volumes of tumor patients. Experiments are performed to compute the average dice scores on BraTS-2019 and BraTS-2020 datasets for the whole tumor region.

  • Smart Asset Management for District Heating Systems in the Baltic Sea Region.
    • Anna Grzegórska
    • Piotr Rybarczyk
    • Valdas Lukoševičius
    • Joanna Sobczak
    • Andrzej Rogala
    2021 Pełny tekst ENERGIES

    The purpose of this review is to provide insight and a comparison of the current status of district heating (DH) systems for selected Baltic Sea countries (Denmark, Germany, Finland, Latvia, Lithuania, Poland, and Sweden), especially from viewpoints of application and solutions of novel smart asset management (SAM) approaches. Furthermore, this paper considers European projects ongoing from 2016, involving participants from the Baltic Sea Region, concerning various aspects of DH systems. The review presents the energy sources with particular attention to renewable energy sources (RES), district heating generations, and the exploitation problems of DH systems. The essential point is a comparison of traditional maintenance systems versus SAM solutions for optimal design, operating conditions, and controlling of the DH networks. The main conclusions regarding DH systems in Baltic Sea countries are commitment towards a transition to 4th generation DH, raising the quality and efficiency of heat supply systems, and simultaneously minimizing the costs. The overall trends show that applied technologies aim to increase the share of renewable energy sources and reduce greenhouse gas emissions. Furthermore, examples presented in this review underline the importance of the implementation of a smart asset management concept to modern DH systems.

  • Smart Cities Concept - Readiness of City Halls as a Measure of Reaching a Smart City Perception
    • Aleksander Orłowski
    2021 CYBERNETICS AND SYSTEMS

    The article presents a proposal for a new approach to the assessment of Smart Cities: testing the readiness of city halls to a Smart City. The approach is the result of two-year studies involving ten major city halls. Readiness is compared with the previously used Smart City assessment methods: rankings or ISO standards. The relationship between readiness and organization maturity was also presented. The key role of city halls in Smart City processes is also discussed. Further, the new approach is verified by selected city halls, NGOs and IT companies.

  • Smart city and fire detection using thermal imaging
    • Magdalena Mazur-Milecka
    • Natalia Głowacka
    • Mariusz Kaczmarek
    • Adam Bujnowski
    • Miłosz Kaszyński
    • Jacek Rumiński
    2021 Pełny tekst

    In this paper, we summarize the results obtained from fire experiments. The aim of the work was to develop new methods of fire detection using IR thermal imaging cameras and dedicated image processing. We conducted 4 experiments in different configurations and with the use of different objects. The conducted experiments have shown the great usefulness of infrared cameras for detecting the seeds of a fire. Even cheap low-resolution bolometric detector modules can detect hot spots.

  • Smart platforms for collaborative urban design and peer-to-peer sharing of resources
    • Dorota Kamrowska-Załuska
    • Barry Hayes
    • Aleksandar Petrovski
    • Clarice Bleil De Souza
    • Cristina Jiménez-pulido
    2021

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  • Smart Specialization through Cluster Policy. Evidence from Poland and Germany
    • Anna Lis
    • Arkadiusz Michał Kowalski
    • Marta Mackiewicz
    2021

    The purpose of the chapter is to investigate the interlinks and commonalities between clusters and regional smart specialization strategies (through the prism of experiences of Polish and German regions). The main research strategy was international comparative analysis, and the basic technique for collecting data was document analysis. The research used the four-level procedure of selecting documents, which allowed identification of detailed information about the cluster policy in Poland and Germany, Regional Smart Specializations in all the regions in both these countries, their leading clusters, and two regions selected for in-depth research (Pomerania and Saxony). The research results show that the cluster policy can be treated as the basis for the implementation of the S3, both in Poland and Germany. This applies in particular to the leading clusters established in each of these countries, which, however, seem to be better suited to the RSS scope in Germany than in Poland. Furthermore, except cluster policy, in the process of emergence of regional smart specializations, previous experiences with regional innovation strategies turned out to be important, as can be seen in the example of German regions. The empirical findings can thus provide some practical implications—policy makers responsible for the implementation of S3 should take into account solutions previously developed both as part of cluster and innovation policy. The findings add to the state-of-the-art knowledge on the link between cluster policy and smart specialization strategy by depicting the roles of leading clusters in S3 implementation in the regional context.

  • Smartphones as tools for equitable food quality assessment
    • Kaja Kalinowska
    • Wojciech Wojnowski
    • Marek Tobiszewski
    2021 Pełny tekst TRENDS IN FOOD SCIENCE & TECHNOLOGY

    Background: The ubiquity of smartphones equipped with an array of sophisticated sensors, ample processing power, network connectivity and a convenient interface makes them a promising tool for non-invasive, portable food quality assessment. Combined with the recent developments in the areas of IoT, deep learning algorithms and cloud computing, they present an opportunity for advancing wide-spread, equitable and sustainable food analytical methods that could be used at each stage of food production and distribution. Scope and Approach: This review focuses on the use of smartphone-based methods in food quality assessment and monitoring, with particular emphasis on the ones in which smartphones are used as detectors, either on their own or in conjunction with more elaborate analytical procedures. The role of these methods in common and equitable access to information on food quality is discussed, together with a consideration of the sustainability and greenness of the smartphone-based methods and a perspective on the methodology and validation. Additionally, recent developments and future research trends are also outlined. Key findings and conclusions: Despite the persisting limitations resulting from technical difficulties and the complexity of the food sample matrix, smartphones will play an increasingly important role in popularizing the access to food analytical techniques for on-site analysis as a readily available and convenient integrated interface, connectivity and remote sensing platforms.

  • Smooth Orthogonal Projections on Riemannian Manifold
    • Marcin Bownik
    • Karol Dziedziul
    • Anna Kamont
    2021 Pełny tekst POTENTIAL ANALYSIS

    We construct a decomposition of the identity operator on a Riemannian manifold M as a sum of smooth orthogonal projections subordinate to an open cover of M. This extends a decomposition on the real line by smooth orthogonal projection due to Coifman and Meyer (C. R. Acad. Sci. Paris, S´er. I Math., 312(3), 259–261 1991) and Auscher, Weiss, Wickerhauser (1992), and a similar decomposition when M is the sphere by Bownik and Dziedziul (Const. Approx., 41, 23–48 2015).

  • Socioemotional Wealth (SEW) of Family Firms and CEO Behavioral Biases in the Implementation of Sustainable Development Goals (SDGs)
    • Elżbieta Bukalska
    • Marek Zinecker
    • Michał Pietrzak
    2021 Pełny tekst ENERGIES

    Agreed upon by the UN member states, Agenda 2030 assumes joint action for long- term sustainable development. These actions are focused on the implementation of 17 Sustainable Development Goals (SDGs), where actions are assumed to lead to the suppression of negative externalities of human activity. It is stressed that the objectives of sustainable development can only be achieved through deep institutional changes in most dimensions of the economy, including the entrepreneurship dimension. Entrepreneurship plays a pivotal role in the sustainable transformation of the community, as the related activities of companies are the source of the desired structural changes. Entrepreneurial projects make the biggest contribution to the objectives of sustainable development through research and development, investment in new technologies, and innovation. The biggest threat to sustainable entrepreneurship is firms’ aggressive corporate financial strategy, which most often results from CEO overconfidence and aggressive financial behavior. The aim of the article is to indicate differences in corporate financial strategies regarding the status of the company (family or non-family) and CEO characteristics (overconfident or non-overconfident). The fulfilment of this aim by analyzing a selected EU member country (Poland) found more aggressive behavior of overconfident CEOs in non-family firms. It was also found that family firms are a fairly coherent group of companies that implement a more conservative corporate financial strategy regardless of CEO characteristics. We can state that family power can curb CEO overconfidence and its impact on aggressive financial strategy. This means that family firms are much more able to create sustainable entrepreneurship and contribute to Sustainable Development Goals (SDGs) within a market framework.

  • Sodium nitrite as a corrosion inhibitor of copper in simulated cooling water
    • Marziya Rizvi
    • Husnu Gerengi
    • Savas Kaya
    • Ilyas Uygur
    • Mesut Yıldız
    • Ibrahim Sarıoglu
    • Zafer Cingiz
    • Michał Mielniczek
    • Brahim El Ibrahimi
    2021 Pełny tekst Scientific Reports

    The corrosion inhibition behavior of sodium nitrite (NaNO2) towards pure copper (99.95%) in simulated cooling water (SCW) was investigated by means of electrochemical impedance spectroscopy (EIS) and dynamic electrochemical impedance spectroscopy (DEIS). NaNO2 interferes with metal dissolution and reduce the corrosion rate through the formation or maintenance of inhibitive film on the metal surface. Surface morphologies illustrated that the surface homogeneity increased on adding sodium nitrite. Sodium nitrite’s adsorption on copper surface followed the modified form of Langmuir, Freundlich and Frumkin isotherms. Physiosorption mode was involved in the corrosion protection. Electrochemical results revealed an corrosion resistance of copper increases on increasing the inhibitor concentration. The DEIS results indicated that copper corrosion mechanism could be hindered by 50% even after interval of 24 h by optimum concentration of sodium nitrite. The maximum inhibition was achieved with 2000 ppm of NaNO2. With this concentration, inhibition efficiency of up to 61.8% was achievable.

  • 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst

    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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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.