Publications Repository - Gdańsk University of Technology

Page settings

polski
Publications Repository
Gdańsk University of Technology

Show publications from the year

Recent items

  • Slowly-closing valve behaviour during steam machine accelerated start-up
    • Mateusz Bryk
    • Mariusz Banaszkiewicz
    • Tomasz Kowalczyk
    • Waldemar Dudda
    • Paweł Ziółkowski
    2022 Full text Case Studies in Thermal Engineering

    The paper discusses the state of stress in a slowly-closing valve during accelerated start-up of a steam turbine. The valve is one of the first components affected by high temperature gradients and is a key element on which the power, efficiency and safety of the steam system depend. The authors calibrated the valve model based on experimental data and then performed extended Thermal-FSI analyses relative to experiment. The issue is important as determining the possibility of accelerating the start-up of a steam turbine while not exceeding the strength limit in the design of the steam valve. The shorter the startup time, the more environmental and economic benefits. The most important results of the work include the possibility to reduce the start-up time of a steam machine without excessive strain on the valve structural components and not to exceed the stress limits. The important news for the industry is that there is no need to change the valves construction in terms of accelerated start-up of the steam engine. The results of the work confirm the belief that fast start-up of a steam turbine is possible without large capital expenditures for design changes in the components of the steam system.

  • Small Polymeric Toys Placed in Child-Dedicated Chocolate Food Products—Do They Contain Harmful Chemicals? Examination of Quality by Example of Selected VOCs and SVOCs
    • Monika Śmiełowska
    • Mariusz Marć
    • Bożena Zabiegała
    2022 Full text Exposure and Health

    This study was focused on child-dedicated chocolate food products that contain a plastic package with a small toy inside (also known as chocolate eggs). Three types of these products that are commercially available on the Polish market, with different prices, chocolate composition, and main types of polymers used in the toy manufacturing process, were investigated. The polymers were identified using Fourier-transform infrared (FT-IR) analysis and emissions of selected toxic volatile organic compounds of toy and packaging samples were identified using stationary emission micro-chamber. Total volatile organic compounds emissions were also estimated. Moreover, the content of polybrominated diphenyl ethers (PBDEs) as bioaccumulative semi-volatile organic compounds was checked in all parts of the cheapest product. The highest PBDE concentra- tions, which ranged from 5.32 ± 0.79 to 1768 ± 289 ng/g, were recorded in chocolate samples. This demonstrates the need for consumer knowledge on the safety of such products available on the Polish market to be broadened. This is one of the many examples of studies showing that products sold on the European market do not always comply with the Conformité Européenne (CE) declaration of conformity. Furthermore, the presence of phased-out PBDEs in toys may provide evidence of wrong recycling practices. Forward-looking considerations showed that, based on assessments of the hazard quotient (HQ) and cancer risk of BDE-209 and assuming each child has contact with one toy and eats one of the studied chocolate products per day, there is no high risk associated with the exposure of children to PBDEs.

  • Smart Knowledge Engineering for Cognitive Systems: A Brief Overview
    • Caterine Silva de Oliveira
    • Cesar Sanin
    • Edward Szczerbicki
    2022 Full text CYBERNETICS AND SYSTEMS

    Cognition in computer sciences refers to the ability of a system to learn at scale, reason with purpose, and naturally interact with humans and other smart systems, such as humans do. To enhance intelligence, as well as to introduce cognitive functions into machines, recent studies have brought humans into the loop, turning the system into a human–AI hybrid. To effectively integrate and manipulate hybrid knowledge, suitable technologies and guidelines are required to sustain the human–AI interface so that communication can occur. However, traditional Knowledge Management (KM) and Knowledge Engineering (KE) approaches encounter problems when dealing with cutting-edge technologies, imposing impediments for the use of traditional methods in cognitive systems (CS). This paper presents a brief overview of the Smart Knowledge Engineering for Cognitive Systems (SKECS), which is based on methods, technologies, and procedures that bring innovations to the fields of KE, KM, and CS. The goal is to bridge the gap in the hybrid cognitive interface by the combination of experience-based knowledge representation with the use of emerging technologies such as deep learning, context-aware indexing/retrieval, active learning with a human-in-the-loop, and stream reasoning. In this work Set of Experience Knowledge Structure (SOEKS) and Decision DNA (DDNA) is extended to the visual domain and utilized for knowledge capture, representation, reuse, and evolution. These technologies are examined throughout the layers of SKECS for applications in knowledge acquisition, formalization, storage/retrieval, learning, and reasoning, with the final goal of achieving knowledge augmentation (wisdom) in CS. Features of the SKECS and their practical implementation is discussed through a case study—the Cognitive Vision Platform for Hazard Control (CVP-HC)—suggesting that methods, techniques and procedures comprising the SKECS are suitable for advancing systems toward augmented cognition.

  • Smart Virtual Product Development: Manufacturing Capability Analysis and Process Planning Module
    • Muhammad Ahmed
    • Cesar Sanin
    • Edward Szczerbicki
    2022 Full text CYBERNETICS AND SYSTEMS

    Smart Virtual Product Development (SVPD) system provides effective use of information, knowledge, and experience in industry during the process of product development in Industry 4.0 scenario. This system comprises of three primary modules, each of which has been developed to cater to a need for digital knowledge capture for smart manufacturing in the areas of product design, production planning, and inspection planning. Manufacturing Capability Analysis and Process Planning (MCAPP) module is an important module of the SVPD system, and it involves the provision of manufacturing knowledge to experts working on product development at the early stages of the product lifecycle. In this research, we firstly describe the structure and working mechanism of the SVPD system’s MCAPP module. This is followed by validation of the MCAPP module’s Manufacturing Process Planning (MPP) sub-module against the key performance indicators (KPIs) by using our threading tap case study. Our results verify the feasibility of our approach and show how manufacturing knowledge relating to features and functions can be used to enhance the manufacturing process across similar products during the early stages of product development. An analysis of the basic concepts and methods of implementation show that this is an expert system capable of supporting smart manufacturing which can play a vital role in the establishment of Industry 4.0.

  • SnO2 nanoparticles embedded onto MoS2 nanoflakes - An efficient catalyst for photodegradation of methylene blue and photoreduction of hexavalent chromium
    • Mariusz Szkoda
    • Zuzanna Zarach
    • Małgorzata Nadolska
    • Grzegorz Trykowski
    • Konrad Trzciński
    2022 ELECTROCHIMICA ACTA

    In this work, a molybdenum disulfide/tin oxide (MoS2/SnO2) composite was successfully prepared via a hydrothermal method. The MoS2/SnO2 composite was used as a photocatalyst for photoreduction of hexavalent chromium and photodecomposition of methylene blue. It exhibited higher photocatalytic performance under simulated solar light irradiation than MoS2 itself. The obtained material was characterized by several spectroscopic and microscopic techniques, namely X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). TEM images of the MoS2/SnO2 revealed that SnO2 nanoparticles were embedded into MoS2. Furthermore, photodegradation mechanism and the role of adsorption were discussed. The enhanced photocatalytic performance of MoS2/SnO2 composite can be directly attributed to the presence of SnO2, which may increase the separation efficiency of the electron-hole pairs. The 99.5% of MB removal was achieved after 5 minutes of illumination. To the best of our knowledge, it is one of the most photoactive MoS2-based photocatalysts for methylene blue (MB) photodecomposition. Moreover, the obtained composite was highly active against chromium (VI) photo-reduction. This work provides evidence that the MoS2/SnO2 composite possesses enormous potential in photocatalytic applications.

  • Social Capital, Human Capital, Tacit Knowledge, and Innovations: A Polish-US Cross-Country Study
    • Wioleta Kucharska
    • G. Scott Erickson
    2022 Full text

    This study measures the relationship between human and social capital (internal and external) and tacit knowledge sharing's influence on innovativeness among knowledge workers employed in Polish (n=1050) and US (n=1118) organizations. The structural equation modeling method revealed that internal social capital matters more for organizational innovativeness in the US. In Poland, both external and internal were important. Specifically, in the US, external social capital supports internal innovativeness directly and external - indirectly. On the contrary, in Poland, social capital directly influences internal and external innovativeness. These differences are partially due to country differences regarding public and private financing. Also apparent is the need for strong social bonds between employees in innovative companies. Furthermore, this study confirms that internal innovativeness is vital for external innovativeness and reveals that social capital is a structural enabler for innovativeness, given its critical role in the distribution of tacit knowledge.

  • Social learning in cluster initiatives
    • Małgorzata Rozkwitalska
    • Anna Lis
    2022 Full text Competitiveness Review

    Purpose – The purpose of the paper is to portray social learning in cluster initiatives (CIs), namely: 1) to explore, with the lens of the communities of practice (CoPs) theory, in what ways social learning occurs in CIs; 2) to discover how various CoPs emerge and evolve in CIs to facilitate a collective journey in their learning process. Subsequently, the authors address the research questions: In what ways does social learning occur in CIs? How is social learning facilitated through the emergence and evolution of various CoPs in CIs? Design/methodology/approach – The study applies the abduction approach for the interpretation of the collected data and attempts to create the best explanations for the observations on the basis of the CoP theory. The qualitative study of four CIs helped to identify various ways that social learning occurs in CIs and the role of the identified CoPs in the process. Social learning is portrayed as a collective journey within and between CoPs, where the interactions of their members deepen their level of involvement and help them to enhance learning in their CoP. Findings – The paper shows ways that social learning occurs in CIs and describes the role of CoPs. It identifies three types of CoPs in CIs: participants, cooperators and locomotives. Additionally, it documents different ways of social learning in CIs, namely one-way or two-way information transfer and raising awareness, demonstrating and inspiring, or motivating and educating. It also shows that while potentially every member of a CI has access to these practices, only a limited number of members are actually involved. Social learning in CIs is selective and some CI members accept their role as more peripheral in their CI. Originality/value – The literature on CIs, which are peculiar forms of clusters, is still underdeveloped. The research fills in the gap concerning the ways social learning occurs in CIs. It shows that selectiveness can be observed in this process, and emphasizes the role of interactions developed through CoPs and the benefits offered by them. The study applies the CoP approach. Consequently, it expands the theoretical base in view of the generally lacking studies on social learning in CIs in the literature on clustering. Since the CoP theory has rarely been applied in the management literature, it also augments this specific field.

  • Social Learning in Cluster Organizations and Accumulation of Technological Capability
    • Małgorzata Rozkwitalska
    • Anna Lis
    2022 Full text Inzinerine Ekonomika-Engineering Economics

    The purpose of the paper is to present how members of cluster organizations perceive their role in the accumulation of technological capability through social learning. The paper presents the results of a qualitative study of four cluster organizations. The theoretical foundation of the study are the communities of practice and the organizational inertia theories. The study indicates that the dynamics of technological capability of cluster organizations’ companies varies regarding three identified communities of practice, namely Participants, Cooperators and Locomotives. The so-called Dead souls (not included in any of the identified communities of practice) did not accumulate technological capability, while the companies classified as Participants increased their technological capability through social learning in cluster organizations provided that the cluster organizations offered comparatively high benefits. Those members of cluster organizations, identified as Cooperators and Locomotives, exhibited relatively high initial technological capability and increased it when the benefits received through social learning in cluster organizations were aligned with their technological trajectories. The study adds to the underdeveloped knowledge of cluster organizations by examining their role in enabling social learning that helps cluster firms accumulate technological capability.

  • Social perception of technological innovations at sports facilities: justification for financing ‘white elephants’ from public sources? The case of Euro 2012 Stadiums in Poland
    • Krystian Zawadzki
    2022 Full text Innovation-The European Journal of Social Science Research

    The main purpose of the paper is to provide a monetary valuation of social benefits in connection with the hypothetical implementation of technological innovations at four Euro 2012 stadiums in Poland. Not only the construction of the sport’s arenas, but also the ongoing maintenance drain the pockets of Polish taxpayers. At the same time Euro 2012 stadiums remain underused, which familiarize the host cities with the concept of ‘white elephants’. Due to the application of the contingent valuation method (CVM), the social effects obtained by the residents of four Polish cities were linked to proposed technological innovations, which were given appropriate monetary values. The research has proved the importance of technological innovations at the Euro 2012 stadiums in Poland. As a result, the residents of four Polish cities valued the social benefits related to the implementation of these innovations at PLN 70 million (USD 18 million).

  • Solar Photovoltaic Energy Optimization and Challenges
    • Arsalan Muhammad Soomar
    • Abdul Hakeem
    • Mustapha Messaoudi
    • Piotr Musznicki
    • Amjad Iqbal
    • Stanisław Czapp
    2022 Full text Frontiers in Energy Research

    The study paper focuses on solar energy optimization approaches, as well as the obstacles and concerns that come with them. This study discusses the most current advancements in solar power generation devices in order to provide a reference for decision-makers in the field of solar plant construction throughout the world. These technologies are divided into three groups: photovoltaic, thermal, and hybrid (thermal/photovoltaic). As a result, this article begins by outlining the approach that will be employed to undertake this research. Following that, solar energy production methods are researched and their sub-classifications are described in order to establish their resource needs and features. Following that, a detailed conversation is held. Each technology’s environmental and economic performance will be evaluated. Furthermore, a statistical analysis is conducted to emphasize the efficiency and performance of each solar technology, as well as to identify their global rankings in terms of power output. Finally, research trends in the development of solar power plants are presented. The credibility of the Photovoltaic system, types and limitations is the discussion under study system makes use of sun’s energy to generate electricity with the help of varied procedural systems; stand-alone, hybrid or grid charged. Based on this research, it is possible to infer that the primary goals of optimization approaches are to reduce investment, operation and maintenance costs, and emissions in order to improve system dependability. This paper also includes a brief overview of several solar energy optimization problems and issues.

  • Solubility of Methane in Water: Some Useful Results for Hydrate Nucleation
    • Joanna Grabowska
    • Samuel Blazquez
    • Eduardo Sanz
    • Iván M. Zerón
    • Jesús Algaba
    • José Manuel Míguez
    • Felipe J. Blas
    • Carlos Vega
    2022 Full text JOURNAL OF PHYSICAL CHEMISTRY B

    In this paper, the solubility of methane in water along the 400 bar isobar is determined by computer simulations using the TIP4P/Ice force field for water and a simple LJ model for methane. In particular, the solubility of methane in water when in contact with the gas phase and the solubility of methane in water when in contact with the hydrate has been determined. The solubility of methane in a gas–liquid system decreases as temperature increases. The solubility of methane in a hydrate–liquid system increases with temperature. The two curves intersect at a certain temperature that determines the triple point T3 at a certain pressure. We also determined T3 by the three-phase direct coexistence method. The results of both methods agree, and we suggest 295(2) K as the value of T3 for this system. We also analyzed the impact of curvature on the solubility of methane in water. We found that the presence of curvature increases the solubility in both the gas–liquid and hydrate–liquid systems. The change in chemical potential for the formation of hydrate is evaluated along the isobar using two different thermodynamic routes, obtaining good agreement between them. It is shown that the driving force for hydrate nucleation under experimental conditions is higher than that for the formation of pure ice when compared at the same supercooling. We also show that supersaturation (i.e., concentrations above those of the planar interface) increases the driving force for nucleation dramatically. The effect of bubbles can be equivalent to that of an additional supercooling of about 20 K. Having highly supersaturated homogeneous solutions makes possible the spontaneous formation of the hydrate at temperatures as high as 285 K (i.e., 10K below T3). The crucial role of the concentration of methane for hydrate formation is clearly revealed. Nucleation of the hydrate can be either impossible or easy and fast depending on the concentration of methane which seems to play the leading role in the understanding of the kinetics of hydrate formation.

  • SOLUTIONS OF THE INTERMEDIATE SUPPORT STRUC- TURES OF THE NORTHERN MARMARA HIGHWAY (ISTAN- BUL’S RING ROAD) IN THE CONTEXT OF SEISMIC ACTIVITY
    • Karol Grębowski
    • Mikołaj Miśkiewicz
    • Krzysztof Wilde
    2022 Full text

    In 2014–2018, as a result of the expansion of the city of Istanbul in Turkey, a project was imple- mented consisting of building a northern ring road, called the Northern Marmara Highway. The concept of the structural design of the ring road’s intermediate supports aims at constructing sup- ports that according to the TURKISH DLH 2008 standard must comply with the design require- ments for the three calculated earthquake insensitivity levels (D1, D2, D3). The article discusses the modelling of plastic hinges in the reinforced concrete intermediate supports using finite elements methods. The Ductility Demand-Capacity method was used to determine the geometrical parame- ters of the cross-section plasticisation zones, their ability to move and rotate, and their ductility. Due to the varied geometry and stiffness of the supports and their non-linear behaviour under dynamic load, this method was concluded to be imperfect. Therefore, an improved algorithm was proposed by determining the main parameters of the plastic hinges depending on the degree of concrete deg- radation according to Lubliner’s assumptions. The new algorithm was used to design the structure of viaducts of the Istanbul Northern Marmara Highway ring road implemented by the authors. The obtained results may help to prevent failures and damage to the viaducts’ supports structure and thus ensure the safety of all users exploiting the objects. Based on the collected results, it was prov- en that the proposed concept of intermediate supports with a variable geometry and stiffness design including the plastic-damage reinforced concrete model, and on the basis of the plastic hinges con- cept, broadens and enriches the issue of analysis of bridge structures exposed to earthquakes.

  • Solvent Exchange around Aqueous Zn(II) from Ab Initio Molecular Dynamics Simulations
    • Adrian Malinowski
    • Maciej Śmiechowski
    2022 Full text Liquids

    Hydrated zinc(II) cations, due to their importance in biological systems, are the subject of ongoing research concerning their hydration shell structure and dynamics. Here, ab initio molecular dynamics (AIMD) simulations are used to study solvent exchange events around aqueous Zn2+, for which observation in detail is possible owing to the considerable length of the generated trajectory. While the hexacoordinated Zn(H2O)62+ is the dominant form of Zn(II) in an aqueous solution, there is a non-negligible contribution of the pentacoordinated Zn(H2O)52+ complex which presence is linked to the dissociative solvent exchange events around Zn2+. The pentacoordinated Zn(II) has a much tighter hydration sphere and is characterized by a trigonal bipyramidal structure, in contrast to the usual octahedral symmetry of the hexacoordinated complex. In total, two full exchange events are registered in the analyzed trajectory. AIMD simulations on an adequate length scale thus provide a direct way of studying such solvent exchange events around ions in molecular detail.

  • Some accelerationist remarks on Marcuse’s drives theory and his dialectics of civilization
    • Andrzej Karalus
    2022 Full text Analiza i Egzystencja

    Marcuse’s theory of civilization offers a promising Freud-Marx synthesis. His approach, best articulated in Eros and Civilization, aims at a thorough reformulation of the Freudian drive doctrine to render it more historical and concatenate it to the problem of structural violence and the institutionalized (and internalized) mechanism of repression. I claim that the said reformulation provides a cornerstone for Marcuse’s highly idiosyncratic variant of a critical theory, which, according to my interpretation, possesses clear proto-accelerationist undertones. The article offers a concise recapitulation of Marcuse’s “dialectics of civilization” and points at the somewhat surprising close convergences with the accelerationist version of postcapitalism in his reflection on politics, technology, and the role of arts and aesthetic imagination in challenging the affirmative (desublimating) character of culture.

  • Some new soliton solutions to the higher dimensional Burger–Huxley and Shallow water waves equation with couple of integration architectonic
    • Farrah Ashraf
    • Tehsina Javeed
    • Romana Ashraf
    • Amina Rana
    • Ali Akgül
    • Shahram Rezapour
    • Muhammad Bilal Hafeez
    • Marek Krawczuk
    2022 Full text Results in Physics

    In this paper, we retrieve some traveling wave, periodic solutions, bell shaped, rational, kink and anti-kink type and Jacobi elliptic functions of Burger’s equation and Shallow water wave equation with the aid of various integration schemes like improved -expansion scheme and Jacobi elliptic function method respectively. We also present our solutions graphically in various dimensions.

  • Sources and composition of chemical pollution in Maritime Antarctica (King George Island), part 1: Sediment and water analysis for PAH sources evaluation in the vicinity of Arctowski station
    • Joanna Potapowicz
    • Małgorzata Szopińska
    • Danuta Szumińska
    • Robert Józef Bialik
    • Żaneta Polkowska
    2022 Full text CHEMOSPHERE

    The paper presents a study regarding the identification of polycyclic aromatic hydrocarbons (PAHs) in fresh waters and surface sediments on the western shore of Admiralty Bay over four sampling seasons from 2017 to 2018. The results were compared to literature data from 2016 to provide a more comprehensive image of the environmental fate of PAHs over the years. The highest value of Σ PAHs was 82.9 ng/L and 445 ng/g dw in water and sediment samples, respectively. The analysis of PAH indicator ratio values showed that pyrogenic or mixed sources contribute to the PAH pollution in Antarctic sediments and water more than does petroleum. The main source is the combustion of biomass (e.g. as a result of fires) and coal, and PAHs are mostly associated with the activity of stations or are transported to a lesser extent by long-range atmospheric transport (LRAT) from South America. The values of the ΣLMW/ΣHMW ratio in sediments indicate that petrogenic sources contribute to PAH contamination, but among the six PAH ratios tested, petrogenic sources were identified as dominant in approximately 17–19% of cases. Lack of coherence in the obtained results confirms the mixed origin of PAHs in the studied samples. Although the differentiation of PAHs sources is still ambiguous, caution is recommended in light of the Antarctic system's evident and rapid response to global and local PAH emissions, and the dependency of accumulation and release cycle processes on weather conditions. A reduction in petrol usage in favour of renewable energy sources, and restriction of tourism are strongly recommended for better preservation of the pristine Antarctic environment.

  • Spatiotemporal Assessment of Satellite Image Time Series for Land Cover Classification Using Deep Learning Techniques: A Case Study of Reunion Island, France
    • Naik Nitesh Navnath
    • Kandasamy Chandrasekaran
    • Andrzej Stateczny
    • Venkatesan Meenakshi Sundaram
    • Prabhavathy Panneer
    2022 Full text Remote Sensing

    Current Earth observation systems generate massive amounts of satellite image time series to keep track of geographical areas over time to monitor and identify environmental and climate change. Efficiently analyzing such data remains an unresolved issue in remote sensing. In classifying land cover, utilizing SITS rather than one image might benefit differentiating across classes because of their varied temporal patterns. The aim was to forecast the land cover class of a group of pixels as a multi-class single-label classification problem given their time series gathered using satellite images. In this article, we exploit SITS to assess the capability of several spatial and temporal deep learning models with the proposed architecture. The models implemented are the bidirectional gated recurrent unit (GRU), temporal convolutional neural networks (TCNN), GRU + TCNN, attention on TCNN, and attention of GRU + TCNN. The proposed architecture integrates univariate, multivariate, and pixel coordinates for the Reunion Island’s landcover classification (LCC). the evaluation of the proposed architecture with deep neural networks on the test dataset determined that blending univariate and multivariate with a recurrent neural network and pixel coordinates achieved increased accuracy with higher F1 scores for each class label. The results suggest that the models also performed exceptionally well when executed in a partitioned manner for the LCC task compared to the temporal models. This study demonstrates that using deep learning approaches paired with spatiotemporal SITS data addresses the difficult task of cost-effectively classifying land cover, contributing to a sustainable environment.

  • Sperm segmentation and abnormalities detection during the ICSI procedure using machine learning algorithms
    • Aleksandra Frączek
    • Gabriela Karwowska
    • Mateusz Miler
    • Joanna Liss
    • Anna Węsierska
    • Magdalena Mazur-Milecka
    2022

    (1) About 15-20% of couples struggle with the problem of infertility. 30 to 40% of these cases are caused by abnormalities in the structure and motility of sperm. Sometimes the only possibility for such people is to use the procedure of artificial insemination. CASA systems are used to increase the efficiency of this procedure by selecting the appropriate sperm cell. (2) This paper presents an approach to the sperm classification on the basis of its entire structure analysis, including flagella - often poorly visible and therefore ignored in the CASA systems element. The training of the Mask R-CNN architecture was performed on 2 publicly available and one specially created for this purpose sperm database. A 14-element feature vector was also proposed for the classification of 4 classes of typical head defects (amorphous, normal, tapered and pyriform) by the Support Vector Machine. (3) The sperm head (mAP 94.28%) and the whole flagellum (mAP 90.29%) were successfully detected. However, the flagella segmentation results were significantly lower (50.88%) than that the head segmentation (88.32%). Classification with SVM scored 82% accuracy. (4) Research has shown that segmentation and the use of a simple SVM classifier allow for quite good results in the classification of sperm defects. However, it is important to develop a larger whole sperm database, to improve the segmentation results.

  • Spiral Search Grasshopper Features Selection with VGG19-ResNet50 for Remote Sensing Object Detection
    • Andrzej Stateczny
    • G. Uday Kiran
    • G. Bindu
    • Kanegonda Ravi Chythanya
    • K. Ayyappa Swamy
    2022 Full text Remote Sensing

    Remote sensing object detection plays a major role in satellite imaging and is required in various scenarios such as transportation, forestry, and the ocean. Deep learning techniques provide efficient performance in remote sensing object detection. The existing techniques have the limitations of data imbalance, overfitting, and lower efficiency in detecting small objects. This research proposes the spiral search grasshopper (SSG) optimization technique to increase the exploitation in feature selection. Augmentation is applied in input images to generate more images, and this helps to train the model and reduces data imbalance problems. The VGG-19 and ResNet50 model is applied for feature extraction, and this helps to extract deep features to represent objects. The SSG feature selection technique increases the exploitation and select unique features for object detection that helps to overcome the data imbalance and overfitting problem. The SSG feature selection model helps to balance the exploration and exploitation that escape from the local optima trap. The SSG model has 82.45% mAP, the SSD model has 52.6% mAP, and the MPFP-Net model has 80.43% mAP.

  • Społeczność akademicka świętuje Tydzień Otwartego Dostępu 2022
    • Kamila Kokot-Kanikuła
    • Agnieszka Szymik
    2022 Full text Pismo PG

    W dniach 24-30 października 2022 roku odbyła się kolejna odsłona święta Otwartego Dostępu pod hasłem „Otwartość dla sprawiedliwości klimatycznej”. Jak co roku w ostatni pełny tydzień października, Biblioteka Politechniki Gdańskiej zorganizowała dla społeczności akademickiej szereg atrakcji, które miały na celu promowanie idee otwartości wśród naukowców i studentów.

  • Spurious Modes in Model Order Reduction in Variational Problems in Electromagnetics
    • Valentin De La Rubia
    • David Young
    • Grzegorz Fotyga
    • Michał Mrozowski
    2022 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES

    In this work, we address an everlasting issue in 2 model order reduction (MOR) in electromagnetics that has 3 remained unnoticed until now. Contrary to what has been 4 previously done, we identify for the very first time spurious 5 modes in MOR for time-harmonic Maxwell’s equations and 6 propose a methodology to remove their negative influence on the 7 reduced order model (ROM) response. These spurious modes 8 have nonzero resonance frequency and may have shown up 9 in the past giving rise to spikes in the frequency response, 10 in effect, deteriorating the accuracy and efficiency of the MOR 11 process. However, they were never characterized as spurious 12 mode contributions, rather they were most likely considered 13 as poor localized approximation issues in the MOR process. 14 When we try to get further physical insights from the ROM, 15 rather than simple frequency domain data, we cannot afford 16 any poorly localized approximation issue, that is, any spurious 17 mode in the band of analysis. Otherwise, these mathematical, 18 but nonphysical, modes will mislead the physical behavior of the 19 device under analysis. A computationally inexpensive variational 20 divergence condition is established to identify spurious modes in 21 the band of analysis, since any physical in-band mode must be 22 divergence-free. In addition, once a spurious mode is identified in 23 the band of analysis, its influence is removed from the ROM by 24 a physics-based coupling strategy. As a result, a robust spurious 25 mode contribution-free MOR in electromagnetics is proposed. 26 Finally, several actual microwave circuits, such as a quad-mode 27 filter and a triple-mode triple-band filter, will illustrate the 28 capabilities and efficiency of the proposed approach.

  • Stability investigation of the PCM nanocomposites
    • Paulina Boroń
    • Maciej Fabrykiewicz
    • Janusz Cieśliński
    2022

    In present study was showed the results of research the stability of nanoPCMs in terms of types and concentrations of surfactant used. For stearic acid has been added PVP or oleic acid in concentrations of 0%, 5% and 10%. Nanoparticles TiO2 and Al-2O3 in concentration of 1% were chosen to be researched in this test. The mixing of nanocomposites has been done in an ultrasonic scrubber in which the samples were placed for 45 mins. The stability was researched through the measurement the changing of temperature over time. The measurements have been done in controlled thermostatic conditions. The results were obtained after clotting the samples from 70°C to 20°C and melting the samples form 20°C to 70°C. The expected results was obtaining plot waveforms with reduced loading time for materials containing surfactants and nanoparticles at their core.

  • Stan przedawaryjny oraz sposób naprawy dźwigarów dachowych z drewna klejonego
    • Maciej Niedostatkiewicz
    • Tomasz Majewski
    2022 Full text

    W artykule przedstawiono opis uszkodzeń konstrukcji dachu sali sportowej, w szczególności drewnianych dźwigarów dachowych z drewna klejonego, które powstały w wyniku popełnionych błędów projektowych oraz wykonawczych. W pracy przedstawiono różne koncepcje naprawy oraz zrealizowane rozwiązanie projektowe wzmocnienia dźwigarów dachowych.

  • Stan przedawaryjny oraz sposób naprawy dźwigarów dachowych z drewna lejonego
    • Maciej Niedostatkiewicz
    • Tomasz Majewski
    2022

    W artykule przedstawiono opis uszkodzeń konstrukcji dachu sali sportowej w szczególności drewnianych dźwigarów dachowych z drewna klejonego które powstały w wyniku popełnionych błędów projektowych oraz wykonawczych. W pracy przedstawiono różne koncepcje naprawy oraz zrealizowane rozwiązanie projektowe wzmocnienia dźwigarów dachowych.

  • Stardust - Investigation of Microbes in the Stratosphere
    • Marcin Jasiukowicz
    • Bartosz Rybacki
    • Mateusz Grzybowski
    • Natalia Czortek
    • Dawid Rekowski
    • Jakub Pawłowski
    • Paulina Podpirko
    • Kacper Loret
    • Dominika Tomaszewska
    • Szymon Magrian
    • Karol Pelzner
    • Remigiusz Galikowski
    • Bartosz Rybak
    • Beata Krawczyk
    2022 Full text

    The stratospheric microbiome has been investigated several times using the methods of classical microbiology. In this experiment, we have combined them with some novel approaches including whole- metagenome amplification, Maldi TOF mass spectrometry and Sanger DNA sequencing. The results of the experiment may provide the scientists with knowledge about the mechanisms of survivability of microorganisms in stratospheric conditions such as high doses of UV and cosmic radiation, low temperature and low humidity. The preliminary results have shown that the stratosphere is very poor in microorganisms in comparison to the regular, tropospheric air. Also the investigation is very difficult due to many problems with both small amounts of biological material and the high risk of contamination. However, contamination is possible to control, and modern methods of biotechnology help in the research of low quantities of material. The experiment was launched from Esrange Space Center in September 2021, onboard BEXUS 30 balloon mission conducted within the REXUS/BEXUS programme.

  • Starodruki w cyfrowej odsłonie – Biblioteka PG zrealizowała projekt Ministerstwa Edukacji i Nauki
    • Anna Sobolewska
    • Kamila Kokot-Kanikuła
    2022 Pismo PG

    Biblioteka Politechniki Gdańskiej ukończyła właśnie realizację projektu „Społeczna Odpowiedzialność Nauki” w ramach modułu „Wsparcie dla bibliotek naukowych”. Projekt realizowany był w ramach konkursu ogłoszonego w 2019 roku przez Ministerstwo Edukacji i Nauki.

  • State tax policy and reform tools as a risk of running a business. Case study based on Polski Ład – Polish tax reform
    • Ewa Łączek-Tarazewicz
    • Jarosław Wróblewski
    • Piotr Kasprzak
    • Gabriela Golawska-Witkowska
    2022

    The aim of the article is to describe and present the Polish tax reform introduced at the beginning of 2022. Tax changes introduced in Poland had a strong impact on the risk of running a business in Poland because in their assumption they directly changed the rules of running a business. Due to the pace of the introduced changes, as well as the scope of the reform, the new tax law was subject to numerous criticisms of taxpayers in Poland (especially entrepreneurs). Although in its initial assumptions, the program of changes entitled The Polish Deal (“Polski Ład) was aimed not only at changing the tax law, but also introducing numerous investment programs as a response to the COVID-19 post-pandemic reality. The article attempts to assess the risk associated with the change of tax law from the point of view of enterprises from the SME sector, and presents the most important assumptions related to the change in the law, as well as the consequences of their introduction.

  • Statistics with R A Handbook for Statistical Analysis with R and R-Studio
    • Karol Flisikowski
    2022

    If you are to perform any kind of data (statistical) analysis and use tools in the data science ecosystem, you may have seen a variety of tutorials, handbooks online (I’m not mentioning traditional bibles of statistics). Unfortunately most of them is written intentionally for specific purposes and/or target group of people and does not include many aspects, data types, difficult aspects, usually hiding them trying to solve theoretical problems of the matter. In this handbook I am not going to omit any of them. What is more, those, which are more problematic for data analyst will be underlined, explained in details, solved with the use of the newest libraries available at the time. Users who believe Python is the best tool for statistical analyses, probably might see some R advantages in the end of the study. We will start with preparing infrastructure for the analysis. Then, the quick tour through the R programming basics. Finally, two most important chapters of this book will walk you through the descriptive and inferential statistical data analysis. Online version is interactive: it means in many places reader will have the chance to go through tutorials, answer some questions, solve some tasks to go to the next page.

  • Stirling engines - the state of technology development and computational models
    • Mariusz Furmanek
    • Jacek Kropiwnicki
    2022 Full text Combustion Engines

    Stirling engines represent a technologically important solution in combined heat and power systems. Their use enables the achievement of over 90 percent efficiency in the management of the primary energy source with a very high durability of the device, mainly due to the lack of contact of the working gas with external factors and a very small number of mechanical components. The use of a Stirling engine may be equally important when applying renewable energy sources or waste heat from other processes. The first part of the work presents an overview of available commercial Stirling engine solutions. The second part of the work presents an overview of numerical models of Stirling engine operation, which enable the correct selection of the main geometrical features of the devices and the improvement of the structure in order to maximize efficiency or power.

  • Stock price reactions to an arrangement approval in restructuring proceedings – the case of Poland
    • Błażej Prusak
    • Marcin Potrykus
    2022 Full text International Journal of Management and Economics

    The study aims to empirically analyze the reaction of stock prices to the information about the conclusion and acceptance of a debtor–creditor arrangement under restructuring proceedings of companies listed on the stock exchange in Poland. The following main research hypothesis was verified: public disclosure of information about an arrangement conclusion and acceptance in restructuring proceedings results in above-average rates of return due to investments in the stocks of these entities in the short term. Three events were assessed: the public disclosure of information about the conclusion of a debtor–creditor arrangement (Event 1), its approval by a court (Event 2), and the decision becoming final (Event 3). The research method applied was the event study. Event 1 and Event 3 leads to an above-average and statistically significant increase in stock prices on the day of the event. In contrast, no statistically significant above-average rates of return accompanied Event 2.

  • Stocznia. Człowiek. Przemysł. Miasto
    • Krzysztof Wróblewski
    2022

    Pierwsza kompleksowa wystawa o historii państwowego przemysłu stoczniowego w Gdańsku, ponad 150 lat dziejów miasta – od połowy XIX wieku, kiedy powstała pierwsza stocznia państwa pruskiego w Gdańsku, poprzez historię dwóch wojen światowych, Stoczni Gdańskiej w czasach komunizmu do współczesności. Wystawa opowiada z perspektywy doświadczenia przemysłu stoczniowego w Gdańsku polityczną, społeczną i kulturową historię Polski i Europy. W centrum opowieści wystawy są losy ludzi, a nie statków. Eksponaty pochodzą od niemal 40 instytucji i osób prywatnych, z Polski i zagranicy. Korzystaliśmy m.in. ze zbiorów Archiwum Państwowego w Gdańsku, PAN Biblioteki Gdańskiej, Muzeum Gdańska, Muzeum Narodowego w Gdańsku, Muzeum Stutthof w Sztutowie, Muzeum Narodowego w Szczecinie, Muzeum Zamoyskich w Kozłówce. Ekspozycja będzie także pierwszą okazją do szerszego zaprezentowania związanych z tym tematem zbiorów ECS.

  • Stocznia i Westerplatte - szkic
    • Krzysztof Wróblewski
    2022

    Obraz odnosi się do dwóch miejsc historycznych w Gdańsku - Stoczni Gdańskiej oraz Westerplatte

  • Stosowanie wyłączników różnicowoprądowych w instalacjach fotowoltaicznych
    • Stanisław Czapp
    2022 INPE: Informacje o Normach i Przepisach Elektrycznych

    Przedstawiono postanowienia norm odnoszące się do doboru i instalowania wyłączników różnicowoprądowych w instalacjach fotowoltaicznych. Zwrócono uwagę, że w instalacjach takich nie ma obowiązku stosowania wyłączników różnicowoprądowych. Omówiono wpływ kształtu przebiegu prądu ziemnozwarciowego ze składową stałą na próg wyzwalania tych zabezpieczeń. Podano przykładowe wartości prądów upływowych w instalacjach fotowoltaicznych i zalecenia co do znamionowego prądu różnicowego zadziałania wyłączników różnicowoprądowych.

  • Straightened characteristics of McKendrick-von Foerster equation
    • Agnieszka Bartłomiejczyk
    • Henryk Leszczyński
    • Milena Matusik
    2022 JOURNAL OF DIFFERENTIAL EQUATIONS

    We study the McKendrick-von Foerster equation with renewal (that is the age-structured model, with total population dependent coefficient and nonlinearity). By using a change of variables, the model is then transformed to a standard age-structured model in which the total population dependent coefficient of the transport term reduces to a constant 1. We use this transformation to get existence, uniqueness of solutions of the problem in a semigroup setting. Since straight lines are more convenient in the exact and approximate solution of PDEs, we provide sufficient conditions of reducing more general equations. We give a difference scheme to find approximate solutions of the age-structured model. Finally, some numerical simulations are presented to demonstrate the convergence and stability of the difference scheme.

  • Strategie treningu neuronowego estymatora częstotliwości tonu krtaniowego z użyciem generatora syntetycznych samogłosek
    • Marek Blok
    • Jan Banaś
    • Mariusz Pietrołaj
    2022 Full text Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    W wielu zastosowaniach telekomunikacyjnych pojawia się problem przetwarzania lub analizy sygnału mowy, w ramach którego, często w obszarze podstawowych algorytmów, stosuje się estymator częstotliwości tonu krtaniowego. Estymator rozpatrywany w tej pracy bazuje na neuronowym klasyfikatorze podejmującym decyzje na podstawie częstotliwości oraz mocy chwilowej wyznaczanych w podpasmach analizowanego sygnału mowy. W pracy rozważamy problematykę treningu tego estymatora, gdy trening odbywa się z użyciem sygnałów generowanych syntetycznie.

  • Stress analysis of suspended rail vehicle bogie
    • Mateusz Kuczyk
    • Piotr Jędrzejewski
    • Paweł Załuski
    2022 Full text Pojazdy Szynowe

    Niniejsza publikacja została poświęcona analizie wytrzymałościowej wybranych elementów wózka – osi zestawu kołowego i ramy. Obliczenia osi wykonano w oparciu o metodę analityczną przy rozpatrzeniu różnych materiałów jej wykonania. Do sprawdzenia wytrzymałości ramy wykorzystano metodę elementów skończonych, a obciążenie wyznaczono zgodnie z wytycznymi normy PN-EN 13749. Sam wózek jest częścią podwieszanego elektrycznego zespołu trakcyjnego zaprojektowanego w ramach pracy dyplomowej pt. „Koncepcja wagonu silnikowego kolei podwieszanej”, na wydziale Mechanicznym Politechniki Gdańskiej.

  • Stress Detection of Children With ASD Using Physiological Signals
    • Sevgi Nur Bilgin Aktas
    • Pinar Uluer
    • Buket Coskun
    • Elif Toprak
    • Duygun Erol Barkana
    • Hatice Kose
    • Tatjana Zorcec
    • Ben Robins
    • Agnieszka Landowska
    2022

    This paper proposes a physiological signal-based stress detection approach for children with autism spectrum disorder (ASD) to be used in social and assistive robot inter- vention. Electrodermal activity (EDA) and blood volume pulse (BVP) signals are collected with an E4 smart wristband from children with ASD in different countries. The peak count and signal amplitude features are derived from EDA signal and used in order to detect the stress of children based on the previously provided reference baselines. Furthermore, a comparison has been made with the stress values determined using low frequency (LF) and high frequency (HF) values extracted from BVP signal.

  • Stress Detection of Children with Autism using Physiological Signals in Kaspar Robot-Based Intervention Studies
    • Buket Coskun
    • Pinar Uluer
    • Elif Toprak
    • Duygun Erol Barkana
    • Hatice Kose
    • Tatjana Zorcec
    • Ben Robins
    • Agnieszka Landowska
    2022

    This study aims to develop a stress detection system using the blood volume pulse (BVP) signals of children with Autism Spectrum Disorder (ASD) during robot-based interven- tion. This study presents the heart rate variability (HRV) analysis method to detect the stress, where HRV features are extracted from raw BVP signals recorded from an E4 wristband during interaction studies with the social robot Kaspar. Low frequency power (LF) and high frequency power (HF) features are analyzed, and the results are verified with facial emotion analysis of the children with ASD. 21 children from 3 countries participated in the study. The results showed that physiological signals combined with affective state labels may predict the stress of children, and the children were not stressed overall their interaction with the Kaspar robot. In specific cases, the children started their session as stressed but their stress declined by the end of the session. These findings are also supported by the results of the vision- based affective state analysis

  • Stress–strain model of lower corroded steel plates of normal strength for fitness-for-purpose analyses
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    • Paweł Kłosowski
    2022 Full text CONSTRUCTION AND BUILDING MATERIALS

    This study investigates the mechanical properties of specimens made of normal strength steel subjected to lower marine immersed corrosion degradation levels (below 25 %). The specimens were corroded in laboratory conditions, and only natural factors were controlled to raise the corrosion rate (reaching the level of 1 mm/year). Three different thicknesses of plates made of normal strength of shipbuilding steel are investigated (between 5 and 8 mm). The standard tensile tests are performed for estimating the stress–strain behaviour of corroded specimens. Non-corroded specimens were tested to establish the initial mechanical properties and uncertainty level as a reference. Further, the corroded specimens were tested too. Based on that, the changes in mechanical properties (i.e. yield stress, Young modulus, ultimate tensile stress and total elongation) were analysed. It was found, that for degradation level reaching 25%, approximately 10% reduction of yield stress was observed. A new parameter, defining the area reduction, was established as more closely related to the mechanical properties deterioration than the commonly used a mean degradation level. The bilinear stress–strain model of corroded steel plates was proposed for the fitness-for-purpose analyses in the structural integrity assessment.

  • Strong ellipticity within the Toupin–Mindlin first strain gradient elasticity theory
    • Victor Eremeev
    • Markus Lazar
    2022 Full text MECHANICS RESEARCH COMMUNICATIONS

    We discuss the strong ellipticity (SE) condition within the Toupin–Mindlin first strain gradient elasticity theory. SE condition is closely related to certain material instabilities and describes mathematical properties of corresponding boundary-value problems. For isotropic solids, SE condition transforms into two inequalities in terms of five gradient-elastic moduli.

  • Structural and electrochemical heterogeneities of boron-doped diamond surfaces
    • Sandra Bogdanowicz
    • Jacek Ryl
    2022 Full text Current Opinion in Electrochemistry

    This brief review is focussed on the recent progress in studies of the heterogeneous electrochemical behaviour of various boron-doped materials extending from zero-dimensional particles through polycrystalline or nanostructured three-dimensional surfaces. A boron-doped diamond reveals large heterogeneities induced by numerous factors, inter alia multi-faceted crystallinity, inhomogeneous boron concentration, sp2/sp3-carbon ratio, surface terminations and grain size distribution. We also present single nanodiamond particles and a nanostructured diamond, which are fabricated by either a top-down or a bottom-up procedure. Nanoarchitectured surfaces allow high areas and large aspect ratios to be achieved, exhibiting highly heterogeneous charge-transfer performance for catalytic, sensing and energy applications. We have anticipated multi-factor-originated heterogeneities of various boron-doped diamond surfaces displaying the essential fabrication and diagnostic methodologies and critically reviewing their benefits and drawbacks.

  • Structural properties of mixed conductor Ba1−xGd1−yLax+yCo2O6−δ
    • Ragnar Strandbakke
    • David S. Wragg
    • Magnus Helgerud Sørby
    • Matylda N. Guzik
    • Anette E. Gunnæs
    • Iga Szpunar
    • Sebastian Wachowski
    • María Balaguer
    • Patricia A. Carvalho
    • Aleksandra Mielewczyk-Gryń
    • Jose M. Serra
    • Truls Norby
    2022 Full text DALTON TRANSACTIONS

    Ba1−xGd1−yLax+yCo2O6−δ (BGLC) compositions with large compositional ranges of Ba, Gd, and La have been characterised with respect to phase compositions, structure, and thermal and chemical expansion. The results show a system with large compositional flexibility, enabling tuning of functional properties and thermal and chemical expansion. We show anisotropic chemical expansion and detailed refinements of emerging phases as La is substituted for Ba and Gd. The dominating phase is the double perovskite structure Pmmm, which is A-site ordered along the c-axes and with O vacancy ordering along the b-axis in the Ln-layer. Phases emerging when substituting La for Ba are orthorhombic Ba-deficient Pbnm and cubic LaCoO3-based R[3 with combining macron]c. When La is almost completely substituted for Gd, the material can be stabilised in Pmmm, or cubic Pm[3 with combining macron]m, depending on thermal and atmospheric history. We list thermal expansion coefficients for x = 0–0.3, y = 0.2.

  • Structure and Stability Characterization of Natural Lake Pigments Made from Plant Extracts and Their Potential Application in Polymer Composites for Packaging Materials
    • Bolesław Szadkowski
    • Małgorzata Kuśmierek
    • Magdalena Śliwka-Kaszyńska
    • Anna Marzec
    2022 Full text Materials

    Natural dyes were extracted from various plant sources and converted into lake pigments based on aluminum and tin. Three different plants (weld, Persian berries, and Brazilwood) were chosen as representative sources of natural dyes. High-performance liquid chromatography (HPLC) and triple-quadrupole mass spectrometry (QqQ MS) were used to identify dyestuffs in the raw extracts. The natural dyes and lake pigments were further characterized by optical and scanning electron microscopy (SEM), UV-Vis spectrophotometry, and thermogravimetric analysis (TGA). The stabilization of the studied plant extracts onto aluminum and tin salts led to the formation of natural lake pigments characterized by different color shades. The natural lake pigments showed improved thermal and chemical stability, which was confirmed by their higher degradation temperatures and lower solubility in chemical agents compared to natural dyes extracted from plants. This improvement can be attributed to electrostatic attraction due to the process of chelation. Ethylene- norbornene (EN) composites colored with the lake pigments exhibited uniform color and improved resistance to long-term UV exposure aging. After 300 h of UV exposure, the aging factor of the neat EN copolymer reduced to 0.3, indicating an advanced aging process of polymer compared to colored samples. Prolonged UV exposure deteriorated the mechanical properties of EN by approximately 57%, compared to about 43% with the application of BW/Al lake pigment. Natural lake pigments could be used as effective substitutes for commercial colorants in plastics for packaging applications.

  • Structure and the Biochemical Potential of the Bacterial Community in Wastewater Treatment Plant Effluent and in Receiving Waters: Northern Poland Case Study
    • Agnieszka Kalinowska
    • Mattia Pierpaoli
    • Krystyna Kozioł
    • Katarzyna Jankowska
    • Sylwia Fudala-Kaiążek
    • Anna Remiszewska-Skwarek
    • Aneta Łuczkiewicz
    2022

    Wastewater treatment processes are monitored mainly in terms of biogenic substance removal efficiency. Little is known about the treated wastewater microbiome and its influence on the recipient. In this study, a wide range of methods (cultivation, microscopic analysis, New Generation Sequencing and Real Time PCR) were employed to determine the bacterial community composition of the treated wastewater and its receiver. Preliminary results of the study show that the wastewater impact on the marine receiver is not clearly visible on the higher taxonomic level of the microbial community (phylum) or in microscopic observations. However, it can be noted in the results of cultivation methods (eg. E. coli presence) and in the lower taxonomic levels, eg. specific groups of human-related bacteria, including pathogens, as well as microorganisms involved in nutrient cycling.

  • Struktury oraz mapy przepływu R1233zd w okrągłym minikanale przy średnich i wysokich wartościach ciśnienia zredukowanego [w:] Postępy w badaniach wymiany ciepła i masy
    • Stanisław Głuch
    • Michał Pysz
    • Dariusz Mikielewicz
    2022 Full text

    W wiedzy dotyczącej struktur przepływu niskowrzących czynników roboczych w zakresie wysokich temperatur nasycenia (powyżej 120°C) oraz średnich i wysokich wartościach ciśnienia zredukowanego (0.5-0.9) występuje luka. W literaturze obecne są dane dotyczące podobnych wartości ciśnień zredukowanych, ale dla niższych wartości temperatury nasycenia (głównie z zakresu -20°C do 40°C). Wynika to z dotychczasowych zastosowań chłodniczych tych czynników. Stosuje się je oprócz chłodnictwa w energetyce. Przy wysokich wartościach ciśnienia zredukowanego gęstość fazy gazowej jest stosunkowo wysoka, a gęstość fazy ciekłej niska. Pomiędzy fazą ciekłą i gazową występuje niska różnica objętości właściwej. Faza ciekła ma niską wartość napięcia powierzchniowego. Faza gazowa charakteryzuje się stosunkowo wysoką lepkością, a faza ciekła ma obniżoną lepkość. Te zmiany parametrów czynników chłodniczych powoduje znaczne różnice w strukturach przepływu. Przy niskiej wartości ciśnienia zredukowanego, 0,2, zaobserwowano wystąpienie przepływu pierścieniowego już przy stopniu suchości 0,07 dla prędkości masowej G=355 [kg/(m^2*s)], natomiast dla ciśnienia zredukowanego o wartości 0,6 przepływ pierścieniowy występuje dużo później, przy stopniu suchości 0,4 dla tej samej prędkości masowej. Zaprezentowano mapy przepływu prędkości masowej w funkcji stopnia suchości dla stałych wartości ciśnienia zredukowano oraz mapy przepływu dla ciśnienia zredukowanego w funkcji stopnia suchości przy stałej prędkości masowej.

  • Students and Young Professionals of the IEEE IES in the Time of Information, Automation, and Energy Transformation [Students and Young Professionals News]
    • Wenbin Dai
    • Kim Fung Tsang
    • Lucia Lo Bello
    • Yousef Ibrahim
    • Frivaldsky Michal
    • Marek Turzyński
    • Ludwig S. Sahesch-Pur
    • Regina Roos
    • Auday Al-Dulaimy
    • Moris Behnam
    • Marek Jasinski
    2022 Full text IEEE Industrial Electronics Magazine

    Reports on IEEE IES Society student activities in year 2021.

  • Study of the anticancer potential of Cd complexes of selenazoyl-hydrazones and their sulfur isosters
    • Sanja B. Marković
    • Natalia Maciejewska
    • Mateusz Olszewski
    • Aleksandar Višnjevac
    • Adrián Puerta
    • José M. Padrón
    • Irena Novaković
    • Snežana Kojić
    • Henrique S. Fernandes
    • Sérgio F. Sousa
    • Sandra Ramotowska
    • Agnieszka Chylewska
    • Mariusz Makowski
    • Tamara R. Todorović
    • Nenad R. Filipovići
    2022 EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY

    The biological activity of Cd compounds has been investigated scarce since Cd has been recognized as a human carcinogen. However, the toxicity of cadmium is comparable to the toxicity of noble metals such as Pt and Pd. The paradigm of metal toxicity has been challenged suggesting that metal toxicity is not a constant property, yet it depends on many factors like the presence of appropriate ligands. Studies on anticancer activity of cadmium complexes showed that the complexation of various ligands resulted in complexes that showed better activities than approved drugs. In the present study, cadmium complexes with biologically potent thiazolyl/selenazoyl-hydrazone ligands have been prepared, and tested for their activity against different types of tumor cell models. The complexation of ligands with Cd(II) resulted in a synergistic effect. The antiproliferative activity study revealed that all complexes are more active compared to 5-fluorouracil and cisplatin. The mechanism of tumor cell growth inhibition reveal that selenium-based compounds induce cell death in T-47D (gland carcinoma) cells through apoptosis via caspase-3/7 activation. Additionally, their pro-apoptotic effect was stronger compared to etoposide and cisplatin. Nuclease activity, detected by gel electrophoresis, may be the possible mechanism of anticancer action of investigated complexes.

  • Study of the Effectiveness of Model Order Reduction Algorithms in the Finite Element Method Analysis of Multi-port Microwave Structures
    • Grzegorz Fotyga
    2022

    The purpose of this paper is to investigate the effectiveness of model order reduction algorithms in finite element method analysis of multi-port microwave structures. Consideration is given to state of the art algorithms, i.e. compact reduced-basis method (CRBM), second-order Arnoldi method for passive-order reduction (SAPOR), reduced-basis methods (RBM) and subspace-splitting moment-matching MOR (SSMM-MOR)

  • Study of the Layer-Type BST Thin Film with X-ray Diffraction and X-ray Photoelectron Spectroscopy
    • Agata Lisińska-Czekaj
    • Dionizy Czekaj
    2022 Full text Materials

    In the present paper, results of X-ray photoelectron studies of electroceramic thin films of barium strontium titanate, Ba1xSrxTiO3 (BST), composition deposited on stainless-steel substrates are presented. The thin films were prepared by the sol-gel method. A spin-coating deposition of BST layers with different chemical compositions was utilized so the layer-type structure of (0-2) connectivity was formed. After the deposition, the thin-film samples were heated in air atmosphere at temperature T = 700 C for 1 h. The surfaces of BST thin films subjected to thermal treatment were studied by X-ray diffraction. X-ray diffraction measurements confirmed the perovskite-type phase for all grown thin-film samples. The oxidation states of the elements were examined by the X-ray photoelectron spectroscopy method. X-ray photoelectron spectroscopy survey spectra as well as high-resolution spectra (photo-peaks) of the main metallic elements, such as Ti, Ba, and Sr, were compared for the layer-type structures, differing in the deposition sequence of the barium strontium titanate layers constituting the BST thin film.

  • Study of the Resistance to Influence of Aggressive Liquids on Concrete with Lightweight Aggregate
    • Marzena Kurpińska
    • Elżbieta Haustein
    • Filip Kurpiński
    2022 Full text

    The corrosion of the structure of concrete caused by the aggressive external environment is one of the main problems that can reduce the durability of buildings. The paper analyzes the influence of the type of component on selected properties of lightweight concrete (LWC) exposed to aggressive liquids. When lightweight concrete containing porous aggregates is used, the influence of an aggressive environment may be of particular importance. The monograph presents the results of tests of four light concretes with different water-cement ratios and different compositions, which were exposed to aggressive liquids. The concrete mixes were prepared with a granulated expanded glass aggregate (GEGA) and granulated sintered ash aggregate (GAA) with a mineral additive silica fly ash. LWC specimens were curing in laboratory for one year and then subjected to aggressive liquids for 60 days. The types of environments were: strong acid—HCl, 1% and 2% concentration, weak acid—CH3COOH, 1% and 2% concentration, and an aqueous salt solution of Na2SO4, 1% and 2% concentration. Then, the structure was analyzed and the influence of aggressive liquids on the compressive strength of the LWC was examined. Moreover, the change in weight of lightweight concrete samples after corrosion was determined. The obtained test results indicate that the test method can be used for the accelerated estimation of the influence of aggressive liquids on the LWC. LWC with GEGA and GAA aggregates show high resistance to aggressive liquids. Moreover, the research results indicate that the most aggressive solution was HCl solution, while Na2SO4 turned out to be the least aggressive. The higher the concentration of the destructive factor, the faster the corrosion progressed. Concretes containing aggregates made of foamed glass and sintered fly ash are suitable for use both in traditional construction and in facilities exposed to an aggressive environment.