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Politechniki Gdańskiej

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  • Comparative Analysis of Metabolic Variations, Antioxidant Profiles and Antimicrobial Activity of Salvia hispanica (Chia) Seed, Sprout, Leaf, Flower, Root and Herb Extracts
    • Sara Motyka
    • Barbara Kusznierewicz
    • Halina Ekiert
    • Izabela Korona-Głowniak
    • Agnieszka Szopa
    2023 Pełny tekst MOLECULES

    The purpose of this study was to evaluate the phytochemical profiles of the seeds, sprouts, leaves, flowers, roots and herb of Salvia hispanica and to demonstrate their significant contribution to antioxidant and antimicrobial activities. Applied methods were: HPLC-DAD coupled with post-column derivatization with ABTS reagent, untargeted metabolomics performed by LC-Q-Orbitrap HRMS, and two-fold micro-dilution broth method, which involved suspending a solution of tested compounds dissolved in DMSO in Mueller–Hinton broth for bacteria or Mueller–Hinton broth with 2% glucose for fungi. Metabolomic profiling using LC-Q-Orbitrap HRMS used in this study yielded the identification and preliminary characterization of one hundred fifteen compounds. The dominant class of compounds was terpenoids (31 compounds), followed by flavonoids (21 compounds), phenolic acids and derivatives (19 compounds), organic acids (16 compounds) and others (fatty acids, sugars and unidentified compounds). The organic and phenolic acids were the most abundant classes in terms of total peak area, with distribution depending on the plant raw materials obtained from S. hispanica. The main compound among this class for all types of extracts was rosmarinic acid which was proven to be the most abundant for antioxidant potential. All tested extracts exhibited considerable antibacterial and antifungal activity. The strongest bioactivity was found in leaf extracts, which presented bactericidal activity against Gram-positive bacteria (S. aureus, S. epidermidis, M. luteus and E. faecalis). The work represents the first compendium of knowledge comparing different S. hispanica plant raw materials in terms of the profile of biologically active metabolites and their contribution to antioxidant, antimicrobial and antifungal activity.

  • Comparative analysis of numerical with optical soliton solutions of stochastic Gross–Pitaevskii equation in dispersive media
    • Muhammad Zafarullah Baber
    • Nauman Ahmed
    • Muhammad Waqas Yasin
    • Muhammad Sajid Iqbal
    • Ali Akgül
    • Muhammad Riaz
    • Muhammad Rafiq
    • Ali Raza
    2023 Pełny tekst Results in Physics

    This article deals with the stochastic Gross–Pitaevskii equation (SGPE) perturbed with multiplicative time noise. The numerical solutions of the governing model are carried out with the proposed stochastic non-standard finite difference (SNSFD) scheme. The stability of the scheme is proved by using the Von-Neumann criteria and the consistency is shown in the mean square sense. To seek exact solutions, we applied the Sardar subequation (SSE) and modified exponential rational functional (MERF) techniques. The exact solutions are constructed in the form of exponential, hyperbolic, and trigonometric forms. Finally, the comparison of the exact solutions with numerical solutions is drawn in the 3D and line plots for the different values of parameters.

  • Comparative analysis of switched reluctance motor control algorithms
    • Galina Demidova
    • Y.d. Derbikov
    • F.s. Petrikov
    • D.v. Lukichev
    • Ryszard Strzelecki
    • A. Anuchin
    2023 Pełny tekst Scientific and Technical Journal of Information Technologies, Mechanics and Optics

    Предмет исследования. Развитие микропроцессорной техники и силовой электроники позволило создавать недорогие и эффективные системы управления различными электромеханическими объектами, которые ранее широко не использовались из-за сложности управления. К таким устройствам можно отнести вентильно-индукторные электрические машины. Данные машины широко применяются в различных практических разработках, например, в тяговом электроприводе, в электроприводе нефтегазовых буровых установок и других направлениях. Вентильно-индукторная электрическая машина, несмотря на свои явные преимущества, является существенно нелинейным объектом, методы управления которым требуют формализации и группировки. Метод.Рассмотрены конструктивные и функциональные особенности вентильно-индукторных электрических машин, а также показаны основные методы их управления. Выполнен сравнительный анализ наиболее известных способов управления. Основные результаты. Приведены основные классические методы управления вентильно-индукторной электрической машиной: применение релейного регулятора тока с ограничением, метод регулирования углов включения/выключения и управление напряжением звена постоянного тока. Продемонстрированы переходные процессы в системе электропривода при использовании рассматриваемых методов. Показано, что путем регулирования углов включения/выключения получена возможность снижения коэффициента осцилляции вращающего момента. Практическая значимость. Выявленные особенности рассмотренных методов позволяют упростить и сократить время разработки эффективной системы управления вентильно-индукторной электрической машиной, а также уменьшить пульсации вращающего момента

  • Comparative Analysis of the Cofee and Cocoa Industry By‑Products on the Performance of Polyethylene‑Based Composites
    • Aleksander Hejna
    • Mateusz Barczewski
    • Paulina Kosmela
    • Olga Mysiukiewicz
    2023 Pełny tekst Waste and Biomass Valorization

    The application of plant-based by-products from the food industry as minimally processed functional fillers for polymeric composites is an increasingly popular trend among researchers and manufacturers. While minimizing the preprocessing of lignocellulosic fillers leads to an increase in the sustainability of the overall composite and a decrease of the carbon footprint, filler modification is usually indispensable to obtaining sufficient mechanical and thermomechanical properties of a composite. The goal of the presented study was a comprehensive analysis of the structure, mechanical and thermal performance of polyethylene-based (PE) composites with spent coffee grounds (FK) and cocoa husks (KK). Differential scanning calorimetry (DSC) measurements showed the antioxidant activity of both fillers, extending the oxidation induction time by 100% (54 min) compared to pure PE (20 min). Composites with up to 5 wt% of the filler were characterized by low porosity (0.5%) and revealed tensile strength of about 20 MPa, which is comparable with the results of unmodified PE. However, the materials' ductility was affected, reducing elongation at break and tensile toughness by two orders of magnitude. In order to quantify changes in adhesion at the interface, a comprehensive analysis of thermomechanical parameters based on dynamic mechanical analysis (DMA) was carried out, including the assessment of interactions on the interface of the composite caused by the increase in free volume inside composites' structure.

  • Comparative Analysis of the Coffee and Cocoa Industry By-Products on the Performance of Polyethylene-Based Composites
    • Aleksander Hejna
    • Mateusz Barczewski
    • Paulina Kosmela
    • Olga Mysiukiewicz
    2023 Waste and Biomass Valorization

    The application of plant-based by-products from the food industry as minimally processed functional fillers for polymeric composites is an increasingly popular trend among researchers and manufacturers. While minimizing the preprocessing of lignocellulosic fillers leads to an increase in the sustainability of the overall composite and a decrease of the carbon footprint, filler modification is usually indispensable to obtaining sufficient mechanical and thermomechanical properties of a composite. The goal of the presented study was a comprehensive analysis of the structure, mechanical and thermal performance of polyethylene-based (PE) composites with spent coffee grounds (FK) and cocoa husks (KK). Differential scanning calorimetry (DSC) measurements showed the antioxidant activity of both fillers, extending the oxidation induction time by 100% (54 min) compared to pure PE (20 min). Composites with up to 5 wt% of the filler were characterized by low porosity (0.5%) and revealed tensile strength of about 20 MPa, which is comparable with the results of unmodified PE. However, the materials' ductility was affected, reducing elongation at break and tensile toughness by two orders of magnitude. In order to quantify changes in adhesion at the interface, a comprehensive analysis of thermomechanical parameters based on dynamic mechanical analysis (DMA) was carried out, including the assessment of interactions on the interface of the composite caused by the increase in free volume inside composites' structure.

  • Comparative Analysis of Unmanned Aerial Vehicles Used in Photogrammetric Surveys
    • Mariusz Specht
    • Szymon Widźgowski
    • Andrzej Stateczny
    • Cezary Specht
    • Oktawia Lewicka
    2023 Pełny tekst TransNav - The International Journal on Marine Navigation and Safety of Sea Transportation

    There are many manufacturers on the market offering various types of Unmanned Aerial Vehicles (UAV). The multitude of drones available on the market means that the choice of a UAV for a specific application appears to be a decision problem to be solved. The aim of this article is a comparative analysis of drones used in photogrammetric surveys. The criteria for evaluating the UAVs were: availability and product support, payload (min. 5 kg), price (PLN 100,000), as well as space available for measurement modules. These are the requirements that must be met for the implementation of the INNOBAT project, the aim of which is to develop an integrated system using autonomous unmanned aerial and surface vehicles, intended for bathymetric monitoring in the coastal zone. The comparative analysis of drones was based on 27 companies producing UAV. Based on the analysis, 6 drones that met the project requirements were selected. They were: Aurelia X6 Pro, Aurelia X8 Standard LE, DroneHexa AG, FOX‐C8 XT, Hercules 10 and Zoe X4. Selected UAVs differ from each other, among others, in the number of rotors, flight duration and resistance to weather conditions. Individual characteristics of drones may have a different rank depending on their application, therefore the selection of UAVs should be made after prioritisation criteria of a given project.

  • Comparative study of a combined heat and power plant retrofitted by CO2 capture during the combustion of syngas from sewage sludge gasification versus zero-emission combustion of hydrogen produced using renewables
    • Kacper Bąk
    • Paweł Ziółkowski
    • Jacek Frost
    • Marta Drosińska-Komor
    2023 Pełny tekst INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

    With ecological requirements aimed at limiting the production of CO2, it is necessary to produce all, or most of the energy from RES. During the transformation process, ecological and highly efficient combustion power plants will be needed. The classic cycle of combined heat and power (CCGT) with green improvements will continue to be one of the most suitable technologies for this task. This article presents the modernization of the CCGT power plant in Zielona Gora in terms of possible solutions to reduce CO2 emissions and cooperation with RES producing hydrogen. Two variants of retrofit were considered: CO2 capture following the combustion of syngas obtained from gasification of sewage sludge, and emission-free hydrogen combustion in a gas turbine. Calculations were made using numerical modelling and the obtained results were validated. Avoided CO2 emissions for both solutions are shown. The proposed upgrades were compared with the basic variant and other gaseous fuels.

  • Comparative Study on Assisted Solvent Extraction Techniques for the Extraction of Biologically Active Compounds from Sideritis raeseri and Sideritis scardica
    • Marika Mróz
    • Edyta Malinowska-Pańczyk
    • Agnieszka Bartoszek-Pączkowska
    • Barbara Kusznierewicz
    2023 Pełny tekst MOLECULES

    The plants in the Sideritis genus are postulated to exhibit several important medicinal properties due to their unique chemical composition. To isolate the targeted phytochemical compounds, the selection of a suitable extraction method is of primary importance. In this work, a comparative study on the phytochemical profiles of various Sideritis raeseri and Sideritis scardica extracts has been carried out. An untargeted metabolomics approach based on ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry was applied to investigate the metabolic differences between extracts obtained by conventional extraction and extractions assisted by microwaves, ultrasounds and high pressure. Additionally, the influence of extraction solvents on HPLC antioxidant profiles obtained following the derivatization of analytes with ABTS reagent was evaluated. A total of 102 metabolites have been putatively identified. The major secondary metabolites groups were classified as flavonoids, terpenoids, phenylethanoid glycosides and phenolic acids. The main antioxidants in the extracts were isoscutellarein and hypolaetin derivatives as well as verbascoside and chlorogenic acid. The results showed that 70% ethanol was the most effective extractant for different classes of phytochemicals including antioxidants. In addition, extraction supported with microwaves, ultrasounds or high pressure improved the overall recovery of metabolites by about 3 times compared to the conventional extraction method.

  • Comparative tests of the wall thickness effect of a glass-reinforced thermosetting plastic coating with a non-circular cross section in a soil-coating object for economic aspect
    • Remigiusz Gut
    • Wiktor Jasiński
    • Andrzej Duszyński
    • Aleksander Czapla
    • Mahesh Ganesapillai
    • Jakub Drewnowski
    2023 Desalination and Water Treatment

    Culvert structures made of plastics are employed extensively in the construction of new facilities as well as the renovation of existing ones. Due to the high costs of materials required for the manufacturing of these goods, the objective of this research is focused to lessen the thickness of the walls, which may, on the other hand, result in a reduction in the stiffness of the system. In the course of the testing, the structure was subjected to both vertical and horizontal displacements, and wall deformations were measured in both the central portion of the section and at the junction. The results of the tests were assessed to determine whether or not the reduction in wall thickness had an effect on the amount of deformation that occurred in the structure’s internal cross-section as well as the wall stresses. GRP pipes with reduced (optimized) wall thickness can withstand comparable loads to the ones with thicker walls, which opens up consideration about possible application of such products for sustainable development of circular economy.

  • Comparative wear test of journal sliding bearings with sintered bronze and Babbitt alloy bushes lubricated by environmentally acceptable/adapted lubricants (EAL)
    • Jacek Frost
    • Wojciech Litwin
    2023 Pełny tekst TRIBOLOGY TRANSACTIONS

    A growing awareness of the negative effects of mineral oils on the natural environment has resulted in the introduction of new regulations related to environmental protection. One of these regulations requires the use of environmentally acceptable/adapted lubricants (EAL) to lubricate marine main shaft bearings, in place of the mineral lubricating oils that have been used for decades. Classification Societies, which supervise the technical condition of ships, record a certain number of failures each year of heavy loaded stern tube bearings lubricated with modern, environmentally friendly lubricants. The reason often given for such failures is that the operating parameters of EAL lubricants are worse than those of mineral oils. The aim of the experimental research reported here was to compare the operating parameters and wear of EAL lubricated journal sliding bearings. For this purpose, two classic mineral lubricating oils and a group of four alternative lubricants from the EAL group were selected. The tests carried out for two types of bearing bushes – sintered bronze and Babbitt – did not show significant differences in terms of operating parameters or journal and bush wear for the entire group of tested lubricants.

  • Comparing Apples and Oranges: A Mobile User Experience Study of iOS and Android Consumer Devices
    • Przemysław Falkowski-Gilski
    • Tadeus Uhl
    2023

    With the rapid development of wireless networks and the spread of broadband access around the world, the number of active mobile user devices continues to grow. Each year more and more terminals are released on the market, with the smartphone being the most popular among them. They include low-end, mid-range, and of course high-end devices, with top hardware specifications. They do vary in build quality, utilized type of material, screen size and screen technology, but the biggest differentiator relates with the CPU (Central Processing Unit), GPU (Graphical Processing Unit), RAM (Random-Access Memory), as well as integrated wireless connectivity modules. Another issue is the type of installed software, particularly the OS (Operating System). Nowadays, two operating systems share approx. 90% of the mobile market, that is iOS from Apple and Android from Google. The first one is a closed environment, dedicated only to devices coming from one man ufacturer. The fragmentation and distribution of different OSs is very low. The price range of different smartphone versions is quite high for a typical user. The second one is an open environment, available on numerous devices coming from various manufacturers. Additionally, this OS may be changed or modified by any interested third-party, which would like to implement, e.g., their own GUI (Graphical User Interface), etc. The fragmentation and distribution of different OSs is very large. The price range of smartphones available on the market is vast. The question remains which option proofs better in terms of quality for the end user. One may assume that if a given solution is intended as a dedicated one, meaning that it is designed to operate on a limited number of, i.e., hardware configurations, it should prove to be more effective. The battery lifetime, stability and efficiency is expected to be high. If some solution is universal, meaning that it could operate on barely any hardware configuration, it would eventually prove to be less effective, less stable, and with a lower expected battery lifetime. This aspect would surely be an interesting hypothesis to investigate.

  • Comparison of Cu1.3Mn1.7O4 spinels doped with Ni or Fe and synthesized via wet chemistry and solid-state reaction methods, designed as potential coating materials for metallic interconnects
    • Łukasz Mazur
    • Damian Koszelow
    • Marek Zajusz
    • Marcin Łapiński
    • Maciej Bik
    • Patryk Zając
    • Anna Adamczyk
    • Paweł Rutkowski
    • Sebastian Molin
    • Tomasz Brylewski
    2023 JOURNAL OF THE EUROPEAN CERAMIC SOCIETY

    The influence of the method applied to synthesize Cu-Mn-O spinel was evaluated. The methods selected for the investigation were EDTA gel processes and solid-state reaction synthesis. From the obtained powders, sinters were prepared and assessed in terms of their properties as potential coating materials. Additionally, the influence of Ni and Fe dopants was evaluated. The results show that the EDTA gel processes method seems to be more suitable for spinel synthesis. This method yields spinels that exhibit electrical conductivity above the required threshold (>50 S/cm) over a temperature range of 400-850°C, and it also ensures continuous spinel matrices and high spinel content. Spinels obtained via solid-state reactions exhibit inferior properties. A higher concentration of Ni allows electrical conductivity to be improved further, while the opposite tendency is observed for Fe. Finally, it was shown that spinels obtained via EDTA gel processes are promising protective-conducting coating materials for SOEC/SOFCs steel interconnects.

  • Comparison of Mathematical Models of Torque Transmitted by Multi-disc Wet Clutch with Experimental Results
    • Marcin Bąk
    • Piotr Patrosz
    • Paweł Śliwiński
    • Paweł Załuski
    • Mykola Karpenko
    2023

    In this article was described the methodology for the experimental study of flows in the prototype of a satellite hydraulic motor with a rotating body. The experimental tests of the motor were carried out at a low constant rotational speed in a wide range of pressure drop in this motor. The constant rotational speed of the motor was kept by a worm gear. Based on the test results, the leakage characteristics in the flat gaps of the curvature, satellites and in the commutation unit gaps were determined. The test results also allowed to evaluate the correct operation of the commutation unit and the compensation unit of axial clearances of the curvature and satellites in the working mechanism of the motor.

  • Comparison of Selected Neural Network Models Used for Automatic Liver Tumor Segmentation
    • Dominik Kwiatkowski
    • Tomasz Dziubich
    2023

    Automatic and accurate segmentation of liver tumors is crucial for the diagnosis and treatment of hepatocellular carcinoma or metastases. However, the task remains challenging due to imprecise boundaries and significant variations in the shape, size, and location of tumors. The present study focuses on tumor segmentation as a more critical aspect from a medical perspective, compared to liver parenchyma segmentation, which is the focus of most authors in publications. In this paper, four state-of-the-art models were trained and used to compare with UNet in terms of accuracy. Two of them (namely, based on polar coordinates and Visual Image Transformer (ViT)) were adopted for the specified task. Dice similarity measure is used for the comparison. A unified baseline environment and preprocessing parameters were used. Experiments on the public LiTS dataset demonstrate that the proposed ViT based network can accurately segment liver tumors from CT images in an end-to-end manner, and it outperforms many existing methods (tumour segmentation accuracy 56%, liver parenchyma 94% Dice). The average Dice similarity measure for the considered images was found to be 75%. The obtained results seem to be clinically relevant.

  • Comparison of the Ability of Neural Network Model and Humans to Detect a Cloned Voice
    • Krzysztof Milewski
    • Szymon Zaporowski
    • Andrzej Czyżewski
    2023 Pełny tekst Electronics

    The vulnerability of the speaker identity verification system to attacks using voice cloning was examined. The research project assumed creating a model for verifying the speaker’s identity based on voice biometrics and then testing its resistance to potential attacks using voice cloning. The Deep Speaker Neural Speaker Embedding System was trained, and the Real-Time Voice Cloning system was employed based on the SV2TTS, Tacotron, WaveRNN, and GE2E neural networks. The results of attacks using voice cloning were analyzed and discussed in the context of a subjective assessment of cloned voice fidelity. Subjective test results and attempts to authenticate speakers proved that the tested biometric identity verification system might resist voice cloning attacks even if humans cannot distinguish cloned samples from original ones.

  • Comparison of the Efficiency of Hetero- and Homogeneous Catalysts in Cellulose Liquefaction
    • Paulina Kosmela
    • Paweł Kazimierski
    2023 Pełny tekst Materials

    Biomass liquefaction is a well-known and extensively described process. Hydrothermal processes are well understood and can be used in the fuel industry. The use of organic solvents can result in full-fledged products for use in the synthesis of polyurethanes. The plastics industry, including polyurethanes, is targeting new, more environmentally friendly solutions. One of these is the replacement of petrochemical polyols with compounds obtained from renewable sources. It is common in biomass liquefaction to use sulfuric acid (VI) as a catalyst. The purpose of the present study was to test the effectiveness of a heterogeneous catalyst such as Nafion ion-exchange resin on the cellulose liquefaction process. The results obtained were compared with the bio-polyols obtained in a conventional way, using a homogeneous catalyst (sulfuric acid (VI)). Depending on the catalyst used and the temperature of the process, bio-polyols characterized, among other things, by a hydroxyl number in the range of 740–400 mgKOH/g were obtained. The research provides new information on the possibility of using heterogeneous catalysts in cellulose liquefaction

  • Comparison of traditional district heating with low temperature district heating systems featuring organic Rankine cycle and heat pump
    • Jaroslaw Mikielewicz
    • Dariusz Mikielewicz
    2023 ENERGY

    Paper presents a comparison between a traditional district heating system with conventional boilers as a source of heat and electricity purchases from power utilities and a low temperature DH system incorporating the CHP with organic Rankine Cycle providing electricity and local heat pump raising the temperature of the DH fluid to the required temperature in the dwelling, meaning that both heat and electricity are produced within the system. Additionally, such “island” system may feature or not the heat pump. Comparisons are made based on the results obtained using a developed simple analytical model enabling calculations of the efficiency of respective systems. The analyses have a general character and can be used in studies of complex networks however presented in the paper simple examples show merely the fundamental capabilities of the developed tool. The objective of the heat pump in the system is to increase temperature of hot water to the required level locally at the dwelling and provide the heating in such way, contrary to the traditional system, where water heating is considered by the use of electric heaters to increase parameters of water for central heating purposes and preparation of utility hot water. Presence of the heat pump in the system allows for significantly lower temperatures of distributed in the network heat carrier.

  • Comparison of various flow maldistribution quantification methods in mini heat exchangers
    • Paweł Dąbrowski
    2023 Pełny tekst Scientific Reports

    The aim of study is to compare various flow maldistribution quantification methods, using velocity, mass flow rate, pressure, and temperature. An experimentally validated numerical study has been prepared and a heat exchanger with 34 semi-circular channels with a diameter of 3.1 mm has been tested. The minichannels were heated from the bottom with a heat flux of 50, 60, 70, and 80 kW/m2. The cases for various inlet velocities of 0.1, 0.2, 0.3, and 0.4 m/s have been tested. It results in a total of 16 cases with various heat flux and various inlet velocities of the water. Then, for every 16 cases, the flow maldistribution coefficients, widely used in the literature, have been calculated based on the velocity, pressure, and temperature profiles. The study shows that every method gives other results of the same parameter that should define the flow distribution in the heat exchanger in the same way. Hence, the ambiguities of fluid distribution conclusions in heat exchangers that can be found in the literature may be caused by a different interpretation of the flow maldistribution coefficient. A normalized flow maldistribution coefficient that gives the same results for all thermohydraulic parameters used has been proposed.

  • Compatibility of Crude Oil Blends─Processing Issues Related to Asphaltene Precipitation, Methods of Instability Prediction─A Review
    • Krzysztof Bambinek
    • Andrzej Przyjazny
    • Grzegorz Boczkaj
    2023 Pełny tekst INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH

    Processing crude oil of variable composition, especially due to the need to process crude oil blends obtained from various sources, presents a tremendous process challenge. This is mainly due to the destabilization of the colloidal system manifested mostly by the precipitation of the asphaltene fraction. The precipitation of asphaltenes from crude oil is a serious problem during extraction, transport, and processing. In the latter case, engineers and scientists have spent a lot of time determining what mechanisms are conducive to the occurrence of this phenomenon. On the one hand, there was a scientific curiosity about the principles of the nanoworld (nanoscale) of asphaltene molecules that determine their stability, and on the other hand, the willingness of process engineers in refineries to maintain the equipment in the best condition and maximize plant profits. Over the years, many methods have been developed to assess the stability of asphaltenes in crude oils and their blends, starting with methodologies based on the separation of a complex mixture into basic groups of compounds with similar properties (SARA) to sophisticated numerical models on an increasingly better understanding of interactions between molecules under changing conditions. In the former case, the basic instruments available in every laboratory are used whereas in the latter case technically advanced measurement systems capable of reproducing the real conditions of crude oil processing are employed. This paper reviews the methods of determining the stability of crude oils and their blends along with a critical assessment of their effectiveness.

  • Compatibility of Sustainable Mater-Bi/poly(ε-caprolactone)/cellulose Biocomposites as a Function of Filler Modification
    • Aleksander Hejna
    • Mateusz Barczewski
    • Paulina Kosmela
    • Olga Mysiukiewicz
    • Adam Piasecki
    • Agnieszka Tercjak
    2023 Pełny tekst Materials

    Despite their popularity and multiplicity of applications, wood–polymer composites (WPCs) still have to overcome particular issues related to their processing and properties. The main aspect is the compatibility with plant-based materials which affects the overall performance of the material. It can be enhanced by strengthening the interfacial adhesion resulting from physical and/or chemical interactions between the matrix and filler, which requires introducing a compatibilizer or a proper modification of one or both phases. Herein, the impact of cellulose filler modifications with varying contents (1–10 wt%) of hexamethylene diisocyanate (HDI) on the compatibility of Mater-Bi/poly(ε-caprolactone) (PCL)-based biocomposites was evaluated. An analysis of surface wettability revealed that the filler modification reduced the hydrophilicity gap between phases, suggesting compatibility enhancement. It was later confirmed via microscopic observation (scanning electron microscopy (SEM) and atomic force microscopy (AFM)), which pointed to the finer dispersion of modified particles and enhanced quality of the interface. The rheological analysis confirmed increased system homogeneity by the reduction in complex viscosity. In contrast, thermogravimetric analysis (TGA) indicated the efficient modification of filler and the presence of the chemical interactions at the interface by the shift of thermal decomposition onset and the changes in the degradation course.

  • Complexity Issues on of Secondary Domination Number
    • Joanna Raczek
    2023 Pełny tekst ALGORITHMICA

    In this paper we study the computational complexity issues of the problem of secondary domination (known also as (1, 2)-domination) in several graph classes. We also study the computational complexity of the problem of determining whether the domination and secondary domination numbers are equal. In particular, we study the influence of triangles and vertices of degree 1 on these numbers. Also, an optimal algorithm for finding a minimum secondary dominating set in trees is presented.

  • Computational Analysis of Transformational Organisational Change with Focus on Organisational Culture and Organisational Learning: An Adaptive Dynamical Systems Modeling Approach
    • Lars Rass
    • Jan Treur
    • Wioleta Kucharska
    • Anna Monika Wiewiora
    2023

    Transformative Organisational Change becomes more and more significant both practically and academically, especially in the context of organisational culture and learning. However computational modeling and formalization of organisational change and learning processes are still largely unexplored. This chapter aims to provide an adaptive network model of transformative organisational change and translate a selection of organisational learning and change processes into computationally modeled processes. Additionally, it sets out to connect the dynamic systems view of organisations to self-modeling network models. The creation of the model and the implemented mechanisms of organisational processes are based on extrapolations of an extensive literature study and grounded in related work in this field, and then applied to a specified hospital-related case scenario in the context of safety culture. The model was evaluated by running several simulations and variations thereof. The results of these were investigated by qualitative analysis and comparison to expected emergent behaviour based on related available academic literature. The simulations performed confirmed the occurrence of an organisational transformational change towards a constant learning culture by offering repeated and effective learning and changes to organisational processes. Observations about various interplays and effects of the mechanism have been made, and they exposed that acceptance of mistakes as a part of learning culture facilitates transformational change and may foster sustainable change in the long run.. Further, the model confirmed that the self-modeling network model approach applies to a dynamic systems view of organisations and a systems perspective of organisational change. The created model offers the basis for the further creation of self-modeling network models within the field of transformative organisational change and the translated mechanisms of this model can further be extracted and reused in a forthcoming academic exploration of this field.

  • Computational Complexity and Its Influence on Predictive Capabilities of Machine Learning Models for Concrete Mix Design
    • Patryk Ziółkowski
    2023 Pełny tekst Materials

    The design of concrete mixtures is crucial in concrete technology, aiming to produce concrete that meets specific quality and performance criteria. Modern standards require not only strength but also eco-friendliness and production efficiency. Based on the Three Equation Method, conventional mix design methods involve analytical and laboratory procedures but are insufficient for contemporary concrete technology, leading to overengineering and difficulty predicting concrete properties. Machine learning-based methods offer a solution, as they have proven effective in predicting concrete compressive strength for concrete mix design. This paper scrutinises the association between the computational complexity of machine learning models and their proficiency in predicting the compressive strength of concrete. This study evaluates five deep neural network models of varying computational complexity in three series. Each model is trained and tested in three series with a vast database of concrete mix recipes and associated destructive tests. The findings suggest a positive correlation between increased computational complexity and the model’s predictive ability. This correlation is evidenced by an increment in the coefficient of determination (R2) and a decrease in error metrics (mean squared error, Minkowski error, normalized squared error, root mean squared error, and sum squared error) as the complexity of the model increases. The research findings provide valuable insights for increasing the performance of concrete technical feature prediction models while acknowledging this study’s limitations and suggesting potential future research directions. This research paves the way for further refinement of AI-driven methods in concrete mix design, enhancing the efficiency and precision of the concrete mix design process.

  • Computational Simulation of the Effects of Different Culture Types and Leader Qualities on Mistake Handling and Organisational Learning
    • Natalie Samhan
    • Jan Treur
    • Wioleta Kucharska
    • Anna Monika Wiewiora
    2023

    This chapter investigates computationally the following research hypotheses: (1) Higher flexibility and discretion in organisational culture results in better mistake management and thus better organisational learning, (2) Effective organisational learning requires a transformational leader to have both high social and formal status and consistency, and (3) Company culture and leader’s behavior must align for the best learning effects. Computational simulations of the introduced adaptive network were analyzed in different contexts varying in organisation culture and leader characteristics. Statistical analysis results proved to be significant and supported the research hypotheses. Ultimately, this chapter provides insight into how organisations that foster a mistake-tolerant attitude in alignment with the leader can result in significantly better organisational learning on a team and individual level.

  • Computationally-Efficient Statistical Design and Yield Optimization of Resonator-Based Notch Filters Using Feature-Based Surrogates
    • Sławomir Kozieł
    • Tanveer Haq Ul
    2023 Pełny tekst Scientific Reports

    Modern microwave devices are designed to fulfill stringent requirements pertaining to electrical performance, which requires, among others, a meticulous tuning of their geometry parameters. When moving up in frequency, physical dimensions of passive microwave circuits become smaller, making the system performance increasingly susceptible to manufacturing tolerances. In particular, inherent inaccuracy of fabrication processes affect the fundamental operating parameters, such as center frequency or bandwidth, which is especially troublesome for narrow-band structures, including notch filters. The ability to quantify the effects of tolerances, and—even more—to account for these in the design process, are instrumental in making the designs more reliable, and to increase the likelihood that adequate operation is ensured despite manufacturing errors. This paper proposes a simple yet computationally efficient and reliable procedure for statistical analysis and yield optimization of resonator-based notch filters. Our methodology involves feature-based surrogate models that can be established using a handful of training data points, and employed for rapid evaluation of the circuit fabrication yield. Furthermore, a yield optimization procedure is developed, which iteratively sets up a sequence of feature-based models, constructed within local domains relocated along the optimization path, and uses them as predictors to find a robust (maximum yield) design at a low computational cost. The presented approach has been demonstrated using two complementary split ring resonator (CSRR)-based notch filters. The cost of statistical design is about a hundred of EM simulations of the respective filter, with yield evaluation reliability corroborated through EM-based Monte Carlo analysis.

  • Computer-Aided Diagnosis of COVID-19 from Chest X-ray Images Using Hybrid-Features and Random Forest Classifier
    • Kashif Shaheed
    • Piotr Szczuko
    • Qaisar Abbas
    • Ayyaz Hussain
    • Mubarak Albathan
    2023 Pełny tekst Healthcare

    In recent years, a lot of attention has been paid to using radiology imaging to automatically find COVID-19. (1) Background: There are now a number of computer-aided diagnostic schemes that help radiologists and doctors perform diagnostic COVID-19 tests quickly, accurately, and consistently. (2) Methods: Using chest X-ray images, this study proposed a cutting-edge scheme for the automatic recognition of COVID-19 and pneumonia. First, a pre-processing method based on a Gaussian filter and logarithmic operator is applied to input chest X-ray (CXR) images to improve the poorquality images by enhancing the contrast, reducing the noise, and smoothing the image. Second, robust features are extracted from each enhanced chest X-ray image using a Convolutional Neural Network (CNNs) transformer and an optimal collection of grey-level co-occurrence matrices (GLCM) that contain features such as contrast, correlation, entropy, and energy. Finally, based on extracted features from input images, a random forest machine learning classifier is used to classify images into three classes, such as COVID-19, pneumonia, or normal. The predicted output from the model is combined with Gradient-weighted Class Activation Mapping (Grad-CAM) visualisation for diagnosis. (3) Results: Our work is evaluated using public datasets with three different train–test splits (70–30%, 80–20%, and 90–10%) and achieved an average accuracy, F1 score, recall, and precision of 97%, 96%, 96%, and 96%, respectively. A comparative study shows that our proposed method outperforms existing and similar work. The proposed approach can be utilised to screen COVID-19-infected patients effectively. (4) Conclusions: A comparative study with the existing methods is also performed. For performance evaluation, metrics such as accuracy, sensitivity, and F1-measure are calculated. The performance of the proposed method is better than that of the existing methodologies, and it can thus be used for the effective diagnosis of the disease.

  • Computer-Aided Greenery Design—Prototype Green Structure Improving Human Health in Urban Ecosystem
    • Dominik Sędzicki
    • Jan Cudzik
    • Lucyna Nyka
    2023 Pełny tekst International Journal of Environmental Research and Public Health

    Increasing population and urbanization, with climate change consequences, such as rising temperatures, influence public health and well-being. The search to improve the quality of life in cities becomes one of the priority objectives. A solution can be found in the role of greenery in an urban environment and its impact on human health. This opens a path toward experimentation on microclimate green structures that can be inserted into dense urban spaces providing human and environmental benefits. The article proposes an automated greenery design method combined with rapid prototyping for such interventions. A theoretical analysis of the problem preceded the introduction of the method. The research process was developed in accordance with the main objectives of the CDIO framework (Conceive, Design, Implement, and Operate) with the SiL (Software in the Loop) and HiL (Hardware in the Loop) methods. Moreover, the applied test model allows for complex evaluation in order to ensure quality and directions for further development.

  • Concentration‐Induced Hetero‐Valent Partial‐Inverse Occupation of Infrared Phosphor
    • Dominik Kreft
    • Jia‐Yu Hsu
    • Ren-jei Chung
    • Yen‐Ling Kuo
    • Chun Che Lin
    • Natalia Majewska
    • Sebastian Mahlik
    • Mu-huai Fang
    2023 Advanced Optical Materials

    Infrared luminescent materials have evoked much attention from chemists and material scientists. Although substantial progress is made in materials design, the luminescent mechanism remains ambiguous in the complex structures, presenting major barriers to developing novel infrared luminescent materials. Herein, this study aims to deliberate a complete discussion on infrared phosphors with concentration-induced hetero-valent partial-inverse occupation. High-resolution synchrotron X-ray diffraction and Raman spectroscopy reveal the subtle structural change in LiGa5(1−x)O8:5xCr3+. Besides, Cr K-edge wavelet analysis and extended X-ray absorption fine structure illustrate the impact of Cr in the second shell of another Cr ion and the practical coordination of Ga and Cr ions. Furthermore, unexpected two-center Cr3+ emissions and the Cr–Cr pair emission are observed at high Cr concentrations. Variation between the zero-phonon line and N-line at different temperatures is demonstrated. Finally, the structural and luminescent properties are comprehensively discussed, providing the origin of the unexpected Cr2 emission. This study not only provides insight into the hetero-valent partial-inverse occupation process in inorganic materials but also sheds light on developing novel infrared luminescent materials.

  • Concept of an Innovative System for Dimensioning and Predicting Changes in the Coastal Zone Topography Using UAVs and USVs (4DBatMap System)
    • Oktawia Specht
    • Mariusz Specht
    • Andrzej Stateczny
    • Cezary Specht
    2023 Pełny tekst Electronics

    This publication is aimed at developing a concept of an innovative system for dimensioning and predicting changes in the coastal zone topography using Unmanned Aerial Vehicles (UAVs) and Unmanned Surface Vehicles (USVs). The 4DBatMap system will consist of four components: 1. Measurement data acquisition module. Bathymetric and photogrammetric measurements will be carried out with a specific frequency in the coastal zone using a UAV equipped with a Global Navigation Satellite System (GNSS)/Inertial Navigation System (INS), Light Detection And Ranging (LiDAR) and a photogrammetric camera, as well as a USV equipped with a GNSS Real Time Kinematic (RTK) receiver and a MultiBeam EchoSounder (MBES). 2. Multi-sensor geospatial data fusion module. Low-altitude aerial imagery, hydrographic and LiDAR data acquired using UAVs and USVs will be integrated into one. The result will be an accurate and fully covered with measurements terrain of the coastal zone. 3. Module for predicting changes in the coastal zone topography. As part of this module, a computer application will be created, which, based on the analysis of a time series, will determine the optimal method for describing the spatial and temporal variability (long-term trend and seasonal fluctuations) of the coastal zone terrain. 4. Module for imaging changes in the coastal zone topography. The final result of the 4DBatMap system will be a 4D bathymetric chart to illustrate how the coastal zone topography changes over time.

  • Conditions for increasing the recognition of degradation in thermal-flow diagnostics, taking into account environmental legal aspects
    • Marta Drosińska-Komor
    • Jerzy Głuch
    • Katarzyna Brzezińska-gołębiewska
    • Michał Piotrowicz
    • Paweł Ziółkowski
    2023 Pełny tekst Journal of Power Technologies

    The ever-increasing demand for electricity and the need for conventional sources to cooperate with renewable ones generates the need to increase the efficiency and safety of the generation sources. Therefore, it is necessary to find a way to operate existing facilities more efficiently with full detection of emerging faults. These are the requirements of Polish, European and International law, which demands that energy facilities operate with the highest efficiency and meet a number of restrictive requirements. In order to improve the operation of steam power plants of electric generating stations, thermal-fluid diagnostics have been traditionally used, and in this paper a three-hull steam turbine, having a high-pressure, a medium-pressure and a low-pressure part, has been selected for analysis. The turbine class is of the order of 200 MW electric. Genetic algorithms (GA) were used in the process of creating the diagnostic model. So far, they have been used for diagnostic purposes in gas turbines, and no work has been found in the literature using GA for the diagnostic process of such complex objects as steam turbines located in professional manufacturing facilities. The use of genetic algorithms allowed rapid acquisition of global extremes, that is efficiency and power of the unit. The result of the work undertaken is the possibility to carry out a full diagnostic process, meaning detection, localization and identification of single and double degradations. In this way 100 % of the main faults are found, but there are sometimes additional ones, and these are not perfectly identified especially for single time detection. Thus, the results showed that with a very high success rate the simulated damage to the geometrical elements of the steam turbine under study is found.

  • CONDITIONS OF THE GREEN TRANSFORMATION. THE CASE OF THE EUROPEAN UNION
    • Katarzyna Cheba
    • Iwona Bąk
    • Michał Pietrzak
    2023 Pełny tekst Technological and Economic Development of Economy

    The main purpose of the paper is to identify the factors that determine the course of green transformation and to assess the current stage and possible directions of change in subsequent years in EU countries. The literature lacks comprehensive studies that show the impact of diverse types of factors on the course of green transformation. For this purpose, two perspectives of the research – economic and environmental – are usually taken into account. This paper also proposes to take social factors into account. The empirical verification was conducted using green growth indicators that are published by the OECD that were compared with factors identified from the literature review. Taxonomic (synthetic) measure of development applying the Weber median and correlation coefficient were used for searching for relationships between the identified groups of indicators described both the changes in the dimension of green growth (internal factors of green transformation) and changes in the dimension of contextual indicators (so-called external factors). The proposed way of combining the results obtained from these two methods of data analysis is also new to research in this field. Its aim is an in-depth exploration of the issue, which enables a 2-step verification of the results obtained.

  • Connected early-career experiences of equality in academia during the pandemic and beyond: Our liminal journey
    • Frederike Scholz
    • Joanna Szulc
    2023 Pełny tekst Gender, Work and Organization

    In this paper, we draw on our subjective experiences as two female early-career academics during the global COVID-19 pandemic. While we acknowledge that the pandemic had negative implications for many female scholars due to compulsory telework or increased family responsibilities, we also want to shed light on the empowering experiences shaped by collegial support that became an important part of our pandemic story. We build on the theory of liminality to explain how the events triggered by the pandemic allowed us to break out of our uncomfortable occupational limbo (i.e., feeling “locked-in” to the identity of a foreign-born PhD graduate) and, through creating a kind of equality, resulted in some unique opportunities and challenges. During these difficult times, shaped by an increasing fear of us or our family catching COVID-19, we embarked on a betwixt-and-between state that allowed us to grow as academics as a part of a collective.

  • Consistency of Quantum Computation and the Equivalence Principle.
    • Marcin Nowakowski
    2023 Pełny tekst Foundations of Science

    The equivalence principle, being one of the building blocks of general relativity, seems to be crucial for analysis of quantum effects in gravity. In this paper we consider the relation between the equivalence principle and the consistency of quantum information processing in gravitational field. We propose an analysis with a looped evolution consisting of steps both in the gravitational field and in the accelerated reference frame. We show that without the equivalence principle the looped quantum evolution cannot be unitary and looses its consistency. For this reasoning the equivalence principle is formulated in terms of the gauge transformations and is analyzed for particles acquiring an appropriate phase associated with the action over the looped path. In consequence, to keep consistency of quantum operations in gravitational field, it is required to keep a quantum variant of the equivalence principle. This proves importance of the quantized version of this fundamental gravitational principle for quantum information processing.

  • Constrained aerodynamic shape optimization using neural networks and sequential sampling
    • Pavankumar Koratikere
    • Leifur Leifsson
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2023

    Aerodynamic shape optimization (ASO) involves computational fluid dynamics (CFD)-based search for an optimal aerodynamic shape such as airfoils and wings. Gradient-based optimization (GBO) with adjoints can be used efficiently to solve ASO problems with many design variables, but problems with many constraints can still be challenging. The recently created efficient global optimization algorithm with neural network (NN)-based prediction and uncertainty (EGONN) partially alleviates this challenge. A unique feature of EGONN is its ability to sequentially sample the design space and continuously update the NN prediction using an uncertainty model based on NNs. This work proposes a novel extension to EGONN that enables efficient handling of nonlinear constraints and a continuous update of the prediction and prediction uncertainty data sets. The proposed algorithm is demonstrated on constrained airfoil shape optimization in transonic flow and compared against state-of-the-art GBO with adjoints. The results show that the proposed constrained EGONN algorithm yields comparable optimal designs as GBO at a similar computational cost.

  • Construction of a simulation model of goods delivery in international road transportation taking into account the functioning efficiency of logistics supply chain
    • Ievgenii Lebid
    • Nataliia Luzhanska
    • Iryna Lebid
    • Alexander Mazurenko
    • Inesa Halona
    • Anatolii Horban
    • Iryna Mykhailenko
    • Ievgen Medvediev
    • Tetiana Sotnikova
    2023 Pełny tekst Eastern-European Journal of Enterprise Technologies [ Восточно-Европейский журнал передовых технологий ]

    The object of this study is the process of goods delivery in international road transport using various types of logistics chains. The problem being solved is due to the need to develop recommendations for exporters of goods to reformat or design new supply chains during wartime. The expediency of organizing foreign trade operations by the cargo owners' own forces or with the involvement of enterprises providing logistics consulting services is considered. A simulation model of goods delivery in international road traffic was built and implemented in the GPSS World simulation automation package. The model involves the optimization of organizational and technological processes related to the activity of both a separate link and the entire supply chain. The study takes into account the components of the time characteristics of the performance of preparatory work when establishing cooperation with institutions and organizations, as well as the direct service of the exporter. The application of the developed model in practical activities will provide an opportunity for exporters to obtain information about the duration and reliability of the stages of a foreign trade operation and the feasibility of involving consulting enterprises in cooperation. At the same time, the simulation results reflect the performance indicators of the proposed supply chains when delivering goods by road transport along various routes. The proposed simulation model will make it possible to reduce the time spent searching for links in the formation of a supply chain by 8–12 %, and the duration of a foreign trade operation by 10–14 %. Thus, the reliability of cooperation with intermediary organizations will increase by 8–11 %

  • Contemporary multifunctional buildings towards a sustainable development of the housing environment
    • Antoni Taraszkiewicz
    • Mateusz Gerigk
    2023 Pełny tekst Środowisko Mieszkaniowe

    Development of contemporary urban centers depends on the basis that buildings present more and more complex structures in terms of size and purpose. They are referred to as multifunctional buildings. This aspiration has its origins in the development of urban centers and in the desire to optimize the built-up areas. The article presents the theory of the approach to the design of multifunctional buildings with a focus on the residential function and the nature of environment that these objects shape. The optimization of the design model shows the multi-threaded nature in the pursuit of determining its functional features. This paper presents a model based approach to the design of multifunctional structures with the residential function based on theoretical considerations and practical knowledge. Examples show an upward trend in the construction of residential complexes. The presented research results show an original, systemic approach to the issue, from the urban context to the architectural environment, which aims to improve the design model constituting a part of larger functional complexes. The integration of systems theory, architectural design and spatial execution provides the methodological framework of the work.

  • Continuous blood pressure monitoring by photoplethysmography - signal preprocessing requirements based on blood flow modelling
    • Artur Poliński
    2023 Pełny tekst PHYSIOLOGICAL MEASUREMENT

    Objective. The aim of the study is to investigate the effect of the signal sampling frequency and low-pass filtering on the accuracy of the localisation of the fiducial points of the photoplethysmographic signal (PPG), and thus on the estimation of the blood pressure (i.e. the accuracy of the estimation). Approach. Statistical analysis was performed on 3,799 data samples taken from a publicly available database. Four PPGfiducial points of each sample signal were examined in the study. Main results. Simulation suggests that for noise-free data, cubic spline interpolation causes the sampling frequency (in the considered range of 62.5–500 Hz) to have only limited influence on localisation of the fiducial point. Better results were obtained for the pulse transit time (PTT)than pulse arrival time (PAT) approach. The acceptable filter band depends on the selected fiducial point and PAT or PTT approach. The best results were obtained for the tangent fiducial point. Significance. The presented results make it possible to estimate the minimum requirements for the sampling frequency and filtering of the PPG signal in order to obtain a reliable estimation of blood pressure

  • Contra Bellum: Bell's Theorem as a Confusion of Languages
    • Marek Czachor
    2023 Pełny tekst ACTA PHYSICA POLONICA A

    Bell's theorem is a conflict of mathematical predictions formulated within an infinite hierarchy of mathematical models. Inequalities formulated at level k ∈ Z are violated by probabilities at level k+1. We are inclined to think that k=0 corresponds to the classical world, while k=1 — to the quantum one. However, as the k=0 inequalities are violated by k=1 probabilities, the same relation holds between k=1 inequalities violated by k=2 probabilities, k=-1 inequalities violated by k=0 probabilities, and so forth. By accepting the logic of the Bell theorem, can we prove by induction that nothing exists?

  • Controlling crystallites orientation and facet exposure for enhanced electrochemical properties of polycrystalline MoO3 films
    • Konrad Trzciński
    • Zuzanna Zarach
    • Mariusz Szkoda
    • Andrzej Nowak
    • Katarzyna Berent
    • Mirosław Sawczak
    2023 Pełny tekst Scientific Reports

    This study focuses on the development and optimization of MoO3 films on commercially available FTO substrates using the pulsed laser deposition (PLD) technique. By carefully selecting deposition conditions and implementing post-treatment procedures, precise control over crystallite orientation relative to the substrate is achieved. Deposition at 450 °C in O2 atmosphere results in random crystallite arrangement, while introducing argon instead of oxygen to the PLD chamber during the initial stage of sputtering exposes the (102) and (011) facets. On the other hand, room temperature deposition leads to the formation of amorphous film, but after appropriate post-annealing treatment, the (00k) facets were exposed. The deposited films are studied using SEM and XRD techniques. Moreover, electrochemical properties of FTO/MoO3 electrodes immersed in 1 M AlCl3 aqueous solution are evaluated using cyclic voltammetry and electrochemical impedance spectroscopy. The results demonstrate that different electrochemical processes are promoted based on the orientation of crystallites. When the (102) and (011) facets are exposed, the Al3+ ions intercalation induced by polarization is facilitated, while the (00k) planes exposure leads to the diminished hydrogen evolution reaction overpotential.

  • Conversion of waste biomass to designed and tailored activated chars with valuable properties for adsorption and electrochemical applications
    • Katarzyna Januszewicz
    • Paweł Kazimierski
    • Anita Cymann-Sachajdak
    • Paulina Hercel
    • Beata Barczak
    • Monika Wilamowska-Zawłocka
    • Dariusz Kardas
    • Justyna Łuczak
    2023 Pełny tekst ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

    Waste biomass, a renewable energy source, is inexpensive material that has great potential in sorp-tion and electrochemical application. The selected waste materials (corncobs, coconut shells, wal-nuts, and pistachio husks) allow to close the production cycle and enable material recycling, which are important aspects in the hierarchy of waste management. The proposed methodology for pro-duction and activation of biochars can be used industrially due to highly porous structure, devel-oped surface area and sorption ability of the obtained activated carbons (AC). A significant increase (from 4 up to more than 10 times) in specific surface area (SSA) is observed for all samples after the CO2 activation process (0.5 h at 800°C) up to 725 m2⸱g-1 for corncobs, 534.9 m2⸱g-1 for pistachio husks, 523 m2⸱g-1 for coconut shells, and 393 m2⸱g-1 for walnut husks. The highest value of SSA is achieved for the AC derived from corncobs. This material is evaluated for use as an adsorbent, re-vealing 99% removal of Rhodamine B (dye/AC ratio of 0.0017) and 69% removal of chromium (dye/AC ratio of 0.0028). Based on the adsorption kinetics analysis, it is demonstrated that the Cr (VI) undergoes physical adsorption, while RhB - chemisorption. In addition, corncob-derived AC exhibits superior electrochemical performance in 6 M KOH compared to the non-activated biochar. A specific capacitance of 70 F⸱g-1 at 5 A⸱g-1 is achieved, along with outstanding rate capability (45 F⸱g-1 at 50 A⸱g-1) and cycling stability (94% at 10 A⸱g-1 after 10 000 cycles). In contrast, the non-activated sample shows only 34 F⸱g-1 at 5 A⸱g-1 and 13 F⸱g-1 at 50 A⸱g-1, with a stability of 91.4%.

  • Core loss resistance impact on sensorless speed control of an induction motor using hybrid adaptive sliding mode observer
    • Tadele Ayana
    • Lelisa Wogi
    • Marcin Morawiec
    2023 Pełny tekst Archives of Electrical Engineering

    Induction motors (IMs) experience power losses when a portion of the input power is converted to heat instead of driving the load. The combined effect of copper losses, core losses, and mechanical losses results in IM power losses. Unfortunately, the core losses in the motor, which have a considerable impact on its energy efficiency, are not taken into account by the generally employed dynamic model in the majority of the studies. Due to this, the motor rating often corresponds to the worst-case load in applications, but the motor frequently operates below rated conditions. A hybridized model reference adaptive system (MRAS) with sliding mode control (SMC) is used in this study for sensorless speed control of an induction motor with core loss, allowing the motor to operate under a variety of load conditions. As a result, the machine can run at maximum efficiency while carrying its rated load. By adjusting the -axis current in the − reference frame in vector-controlled drives, the system's performance is enhanced by running the motor at its optimum flux. Regarding the torque and speed of both induction motors with and without core loss, the Adaptive Observer Sliding Mode Control (AOSMC) has been constructed and simulated in this case. The AOSMC with core loss produced good performance when the proposed controller was tested.

  • Corporate social responsibility and forward default risk mediated by financial performance and goodwill
    • Muhammad Mushafiq
    • Błażej Prusak
    • Magdalena Markiewicz
    2023 JOURNAL OF CLEANER PRODUCTION

    In today’s business environment, corporate social responsibility (CSR) has become an increasingly significant factor for firms. This study is driven by the motivation to add to the current literature by investigating the mediating elements that explain the relationship between CSR and forward default risk. In this paper, we attempt to identify the important mediators and give a more comprehensive explanation of this connection by a thorough assessment of the available literature and empirical research. This study explored the relationship between corporate social responsibility and forward default risk through financial performance and goodwill. The study sample consisted of constituents of Standard and Poor’s (S&P) 500 index. It was found from the results of the study that corporate social responsibility has an effect on forward default risk through goodwill and financial performance. The direct and indirect effect of CSR on forward default risk is more enhanced in a 1-year period, as the effect on 3-year forward default risk is lower. Similar results are found during period of economic upswing; however, there is no mediation in CSR and 1-year forward default risk by goodwill. This study has some policy implications. Overall, the study adds to the growing body of literature (stakeholder theory and corporate finance theory) on the relationship between CSR and the financial aspect of firms and highlights the importance of considering CSR in financial decision-making and risk management.

  • Corrosion degradation impact on mechanical properties of structural steel
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    2023 Pełny tekst

    Recently, extensive research was conducted regarding the impact of corrosion degradation on the mechanical properties of structural steel. Studies show that at the material level, the microstructure is somewhat unchanged due to corrosion degradation. However, the corrosion causes pits and structural surface irregularities that consequently impact the mean stress-strain response of typical coupon specimens subjected to tensile loading. Regrettably, the current industrial standards do not account for that phenomenon and treat the impact of corrosion degradation as the uniform thinning of the structural steel. The presented work aims to acknowledge the recent studies regarding the impact of corrosion degradation on the mechanical properties of structural steel, to show future perspectives and to outline the need for more research in this field.

  • Corrosion mechanisms in columns for atmospheric distillation of crude oil
    • Juliusz Orlikowski
    • Radosław Gospoś
    • Tomasz Olczak
    • Kazimierz Darowicki
    2023 Ochrona przed Korozją

    The paper presents the most common corrosion processes occurring in the columns for atmospheric distillation of crude oil. It describes the mechanisms leading to formation of the chemical compounds, which contribute to corrosion phenomena. The main technological factors influencing corrosion processes have been indicated. The paper also presents the interactions between particular corrosion mechanisms resulting in acceleration or inhibition of corrosion rate.

  • Corrosion Properties of Dissimilar AA6082/AA6060 Friction Stir Welded Butt Joints in Different NaCl Concentrations
    • Aleksandra Laska
    • Marek Szkodo
    • Łukasz Pawłowski
    • Grzegorz Gajowiec
    2023 Pełny tekst International Journal of Precision Engineering and Manufacturing-Green Technology

    A solid-state friction stir welding method which is increasingly used in the marine and shipbuilding industry, has been developed to produce welds with high mechanical properties. In seawater, the oxide layer of aluminium is attacked by Cl− ions resulting in its disruption and formation of pitting corrosion. It is particularly important to determine the electrochemical properties of the produced welds and to evaluate the efect of welding parameters on these properties. The following paper presents a study on the corrosion properties of welds of dissimilar aluminium alloys, AA6082 and AA6060, produced for two diferent tool traverse speeds of 160 and 200 mm/min, with consideration of the size of crystallites and residual stresses in the samples, determined by Williamson-Hall analysis and micro-indentation tests. The results revealed that the size of the crystallites in the welds was larger compared to the base materials and the friction mstir welding process generated residual compressive stresses. Furthermore, the welds exhibited higher corrosion resistance compared to the parent materials. Scanning electron microscope observations indicated that the preferred locations of corrosion propagation for welds are the edges on the joint line formed by the combination of rotational and linear motion of the tool.

  • Cosmic-Time Quantum Mechanics and the Passage-of-Time Problem
    • Marek Czachor
    2023 Pełny tekst Universe

    A new dynamical paradigm merging quantum dynamics with cosmology is discussed.

  • Cost-Efficient Two-Level Modeling of Microwave Passives Using Feature-Based Surrogates and Domain Confinement
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    • Qi-Jun Zhang
    2023 Pełny tekst Electronics

    A variety of surrogate modelling techniques has been utilized in high-frequency design over the last two decades. Yet, the curse of dimensionality still poses a serious challenge in setting up re-liable design-ready surrogates of modern microwave components. The difficulty of the model-ing task is only aggravated by nonlinearity of circuit responses. Consequently, constructing a practically usable surrogate model, valid across extended ranges of material, geometry, and op-erational parameters, is far from easy. As a matter of fact, conventional modeling techniques are merely capable of building models for microwave structures featuring a relatively small num-ber of designable parameters within reduced ranges thereof. One of possible ways of mitigating these obstacles may be the employment of the recently proposed two-stage performance-driven modeling approach. Therein, the surrogate model domain is narrowed-down to the section of the space where the vectors of adequate quality are located, thereby permitting to significantly reduce the cost of acquiring the training data. Seeking even further cost reduction, this work in-troduces a novel modeling framework, which exploits problem-specific knowledge extracted from the circuit responses to achieve substantial cost-savings of training data acquisition. In our methodology, the modeling procedure targets response features instead of the complete re-sponses. The response features are the characteristic locations of the circuit response, such as relevant minima or maxima over selected frequency bands. The dependency of the coordinates of the said features on circuit dimensions is considerably less non-linear than it is observed for the complete characteristics, which enables sizable reduction of the data acquisition cost. Nu-merical validation of our procedure involving three microwave structures corroborates its re-markable efficiency, which allows for setting design-ready surrogates using only a handful of samples.

  • Crack Resistance of Asphalt Concrete Subjected to Environmental Factors
    • Cezary Szydłowski
    • Marcin Stienss
    2023 Pełny tekst NanoWorld Journal

    The paper presents an analysis of the influence of environmental factors on the cracking susceptibility of asphalt concrete resulting in a change in the durability of asphalt pavement. In order to assess the phenomenon, laboratory tests were carried out taking into account the destructive effects of moisture, freeze-thaw cycle and long-term ageing. The influence of both factors occurring simultaneously was also verified. Due to the different methods of assessing resistance to water and frost, the tests were carried out according to four variants of conditioning the samples: Polish Technical Requirements WT:2-2010 and WT:2-2014, AASTHO (American Association of State Highway and Transportation Officials) T 273, AASHTO TP 140 (MIST). Long-term aging was conducted according to AASHTO R 30 for 120 h and also in extended time to 216 h. Finally, ten variants of conditioning samples were tested. Asphalt concrete for wearing course was investigated. Parameters of mixtures with neat (50/70) and SBS-modified (45/80-55) binders were compared. The evaluation of changes in fracture toughness was carried out based on the results of testing SCB (Semicircular bending) specimens with a 10 mm notch depth at a temperature of +10 °C, at a loading rate of 1 mm/min. Fracture toughness, fracture energy and Flexibility Index were assessed. A group of 40 results for each of the mixtures was obtained, taking into account both the dispersion due to material heterogeneity (four samples for each of the conditioning variants) and variation in material properties caused by environmental factors (10 conditioning variants). The influence of water and frost action causes a decrease in fracture toughness and a reduction in fracture energy. Long-term ageing increases the stiffness of the mixture, thus increasing the fracture toughness. A significant increase in the brittleness of the material is observed, which reduces the deformation at fracture and thus the fracture energy. On the basis of the obtained results, it can be concluded that the destructive effect of environmental factors is clearly more visible in the case of a mixture with a neat binder. The comprehensive laboratory test results allowed for probabilistic analysis and reliability estimation related to the assessment of the durability of asphalt mixtures. It could be concluded that asphalt pavements made with the use of modified bitumen are characterized by significantly higher durability.

  • Credit default swaps and banks
    • Muhammad Mushafiq
    2023

    This chapter aims to explore the evolving role of credit default swaps (CDS) in managing and transferring default risk from the perspective of banks from a holistic perspective. This chapter examines credit default swaps (CDSs) as derivative financial instruments that transfer credit risk on debt securities. While CDSs offer benefits such as risk management and risk trading, they also introduce potential systemic risks, as evidenced by their role in the 2008 financial crisis. The collapse of American International Group (AIG) serves as a case study, highlighting the complex interactions between banks, CDSs, and the broader financial system. AIG’s exposure to mortgage-backed securities through CDSs led to significant losses and threatened the stability of the financial system.

  • Cross-Lingual Knowledge Distillation via Flow-Based Voice Conversion for Robust Polyglot Text-to-Speech
    • Dariusz Piotrowski
    • Renard Korzeniowski
    • Alessio Falai
    • Sebastian Cygert
    • Kamil Pokora
    • Georgi Tinchev
    • Ziyao Zhang
    • Kayoko Yanagisawa
    2023

    In this work, we introduce a framework for cross-lingual speech synthesis, which involves an upstream Voice Conversion (VC) model and a downstream Text-To-Speech (TTS) model. The proposed framework consists of 4 stages. In the first two stages, we use a VC model to convert utterances in the target locale to the voice of the target speaker. In the third stage, the converted data is combined with the linguistic features and durations from recordings in the target language, which are then used to train a single-speaker acoustic model. Finally, the last stage entails the training of a locale-independent vocoder. Our evaluations show that the proposed paradigm outperforms state-of-the-art approaches which are based on training a large multilingual TTS model. In addition, our experiments demonstrate the robustness of our approach with different model architectures, languages, speakers and amounts of data. Moreover, our solution is especially beneficial in low-resource settings.