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  • Research of chitosan coatings deposited by electrophoretic deposition method at various voltage and time parameters
    • Klaudia Malisz
    • Beata Świeczko-Żurek
    • Olive Jean-marc
    • Gilles Pecastaings
    • Alina Sionkowska
    • Aleksandra Laska
    • Grzegorz Gajowiec
    2024 MATERIALS CHEMISTRY AND PHYSICS

    The aim of this research is to estimate the electrophoretic deposition main parameters, such as voltage and time duration, that will provide optimal characteristics of the surface layer. Chitosan coatings were synthesized on biomedical Ti13Zr13Nb alloys at 20 V and 30 V and with deposit times of 2min, 5 min, 10 min, and 15 min. Evaluation of the coating was performed by using Scanning Electron Microscope (SEM), Energy-Dispersive Spectroscopy (EDS), Laser-Induced Breakdown Spectroscopy (LIBS), Atomic Force Microscopy (AFM), drop shape analyzer and nanoscratch tester. Homogeneous and continuous coatings are obtained for 2 min and 5 min, regardless of the voltage. Defects in form of bubbles are observed only for 20 V during 10 min, 20 V during 15 min, and 30 V during 10 min. All of the coatings show hydrophilic behavior. The critical loads for delamination range are between 100 mN and 300 mN. It is concluded, that the optimal coating for orthopedic implants is obtained at 20 V, 5 min, because of homogeneity, a contact angle supporting osseointegration and the best adhesion. The optimal one for implant in contact with blood is obtained at 20 V, 2 min, because it is homogenous and shows the lowest hydrophilicity, which should limit the thrombogenicity of the coating.

  • Research on the Flicker Effect in Modern Light Sources Powered by an Electrical Network
    • Romuald Masnicki
    • Janusz Mindykowski
    • Beata Palczynska
    • Dawid Werner
    2024 ENERGIES

    Disruptions in power quality have a negative impact on many energy consumers. These include lighting, where interference manifests itself, among others, in the form of light flickering. The article presents phenomena accompanying the operation of modern light sources against the background of exemplary results of studies on the flicker of conventional light sources, such as incandescent or fluorescent lamps. The flickering effect of light generated in modern lamps can occur under stable voltage conditions in the supply network. The main subjects of the conducted research were solid-state light sources—light-emitting diode (LED) lamps, currently available on the lighting market. To assess the effects of these phenomena, it is necessary to use measures other than those traditionally used. The method used allows for the measurement of flicker resulting from both power supply disturbances and the properties of modern light sources. Using the developed measurement system, it is possible to record temporal changes in flicker coefficients resulting from, for example, changing supply voltage conditions. Due to the possibility of flickering light from sources offered by different manufacturers, as shown by research, it is advisable to carry out measurements at the place of use of the lighting.

  • Residual current devices in electric vehicles charging installations
    • Stanisław Czapp
    2024 Pełny tekst Przegląd Elektrotechniczny

    The main requirements of national regulations and international standards regarding protection against electric shock in electric vehicle charging installations are presented. The principles of using residual current devices (RCDs) in such installations are discussed. It is pointed out that RCDs are mandatory equipment for safe charging of electric vehicles. It is noted that the standards require the use of RCDs having an appropriate type of tripping, due to the fact that in the event of an earth fault in the charging circuit, a DC component of significant value may appear in the earth fault current. A new type of residual current devices for DC installations (DC-RCD) has been indicated.

  • Residual current protective device for circuits of distorted earth fault currents – concept, construction and testing
    • Hanan Tariq
    2024 Pełny tekst

    This dissertation presents behavioral and performance verification and analysis of residual current devices (RCDs), as well as a proposal for the construction of a new RCD protection. The state of the art focuses over pre-existing design of the RCD and its behavior and response to the circuits with distorted (non-sinusoidal) earth fault currents. The study highlights the loopholes of the existing design and depicts the problem of unresponsiveness of the RCD against smooth DC, very low-frequency and very high-frequency earth fault currents. For this, most commonly used types (AC, A, B and F) of RCDs were exposed to a series of testing mechanism more extensive than required by standards. Considering the type of problem a new design has been proposed in this dissertation that can outperform the existing design and can trip at even DC and at high-frequency level (40 kHz). Again, comprehensive testing was conducted to assess the newly designed RCD’s response to such abnormal earth fault current. The test results confirms its efficiency and practicality for real world applications. Hence, the conclusion is provided that this new design is capable of performing its designated function to ensure electrical safety. This new design contributes towards an advancement in the field of low-voltage electrical safety and paves a way for more sensitive RCDs. Moreover, a patent application for this new solution has been submitted to the Polish patent office.

  • Resilient Routing in Communication Networks - A Systems Perspective
    • Jacek Rak
    2024

    This practically focused monograph addresses the latest issues of resilient routing in networked systems. It consists of three parts and offers an in-depth introduction to the resilience of networked systems (Part I), a detailed description of schemes of resilient routing (Part II), and examples of the application of resilience mechanisms in selected communication scenarios (Part III). Topics and features: presents the essentials of network resilience; highlights the main causes of network node and link failures; elaborates on the costs and benefits of investing in resilience; discusses the taxonomy of challenges, faults, attributes, and disciplines of resilience; overviews the major metrics useful in evaluating resilience; provides a detailed classification of resilient routing schemes; analyzes the features of optimization models for selected problems of resilient routing; illustrates the properties of computationally efficient methods for determining the shortest sets of disjoint communication paths; shows the practical use of resilient routing mechanisms in selected communication scenarios with a particular focus on up-to-date concepts such as network virtualization or content-centric networking.

  • Resource constrained neural network training
    • Mariusz Pietrołaj
    • Marek Blok
    2024 Pełny tekst Scientific Reports

    Modern applications of neural-network-based AI solutions tend to move from datacenter backends to low-power edge devices. Environmental, computational, and power constraints are inevitable consequences of such a shift. Limiting the bit count of neural network parameters proved to be a valid technique for speeding up and increasing efficiency of the inference process. Hence, it is understandable that a similar approach is gaining momentum in the field of neural network training. In the face of growing complexity of neural network architectures, reducing resources required for preparation of new models would not only improve cost efficiency but also enable a variety of new AI applications on modern personal devices. In this work, we present a deep refinement of neural network parameters limitation with the use of the asymmetric exponent method. In addition to the previous research, we study new techniques of floating-point variables limitation, representation, and rounding. Moreover, by leveraging exponent offset, we present floating-point precision adjustments without an increase in variables’ bit count. The proposed method allowed us to train LeNet, AlexNet and ResNet-18 convolutional neural networks with a custom 8-bit floating-point representation achieving minimal or no results degradation in comparison to baseline 32-bit floating-point variables.

  • Response Feature Technology for High-Frequency Electronics. Optimization, Modeling, and Design Automation
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2024

    This book discusses response feature technology and its applications to modeling, optimization, and computer-aided design of high-frequency structures including antenna and microwave components. By exploring the specific structure of the system outputs, feature-based approaches facilitate simulation-driven design procedures, both in terms of improving their computational efficiency and reliability. These benefits are associated with the weakly nonlinear relationship between feature point coordinates and design variables, which—in the context of optimization—leads to inherent regularization of the objective functions. The book provides an overview of the subject, a definition and extraction of characteristic points, and feature-based design problem reformulation. It also outlines a number of numerical algorithms developed to handle local, global, and multi-criterial design, surrogate modeling, as well as uncertainty quantification. The discussed frameworks are extensively illustrated using examples of real microwave and antenna structures, along with numerous design cases. Introductory material on simulation-driven design, numerical optimization, as well as behavioral and physics-based surrogate modeling is also included. The book will be useful for readers working in the area of high-frequency electronics, including microwave engineering, antenna design, microwave photonics, magnetism and especially those who utilize electromagnetic (EM) simulation models in their daily routines.

  • Response to David Steigmann’s discussion of our paper
    • Thang X. Duong
    • Mikhail Itskov
    • Roger Sauer
    2024 Pełny tekst MATHEMATICS AND MECHANICS OF SOLIDS

    We respond to David Steigmann's discussion of our paper "A general theory for anisotropic Kirchhoff-Love shells with in-plane bending of embedded fibers, Math. Mech. Solids, 28(5):1274-1317" (arXiv:2101.03122). His discussion allows us to clarify two misleading statements in our original paper, and confirm that its formulation is fully consistent with the formulation of Steigmann. We also demonstrate that some of our original statements criticized by Steigmann are not wrong.

  • Reverberation divergence in VR applications
    • Patryk Rolkowski
    • Piotr Odya
    • Bartłomiej Mróz
    2024 International Journal of Electronics and Telecommunications

    This project aimed to investigate the correlation between virtual reality (VR) imagery and ambisonic sound. With the increasing popularity of VR applications, understanding how sound is perceived in virtual environments is crucial for enhancing the immersiveness of the experience. In the experiment, participants were immersed in a virtual environment that replicated a concert hall. Their task was to assess the correspondence between sound scenes (which differed in reverberation times and their characteristics) and the observed invariant visual scene. The research was conducted using paired tests. Participants were asked to identify the sound scene they considered more closely matched the concert hall seen in the VR goggles for each pair. Each sound scene differed in the employed impulse response. All the impulse responses were recorded in real venues such as concert halls, auditoriums, churches, etc. To provide a realistic auditory experience, the sound scenes were processed using third-order ambisonics and decoded using binaural techniques with HRTFs. The virtual concert hall was generated using the Unreal Engine and was the same for all the tests. One of the major conclusions drawn from the conducted research was confirming the role of spatial sound in creating immersive VR experiences. The study demonstrated that appropriately matching spatial sound to the VR visual scene is essential for achieving complete immersion. Additionally, expectations and preferences regarding reverberation characteristics in different types of spaces were discovered. These findings have significant implications for the design of virtual environments, and understanding these aspects can contribute to improving VR technology and creating more immersive and realistic virtual experiences for users.

  • Review of Recent Advancement on Nature/Bio-inspired Antenna Designs
    • Farooq Azam
    • Syed Shah
    • Shahid Bashir
    • Sławomir Kozieł
    2024 Pełny tekst IEEE Access

    This article presents an extensive examination of antennas rooted in nature and biology, showcasing their remarkable performance across a wide spectrum of frequencies—from microwave to terahertz. The limitations of traditional antenna design have become increasingly evident in the face of burgeoning demands for novel communication technologies. Conventional analytical-equation-based approaches struggle to deliver the combined performance characteristics – encompassing bandwidth, gain, radiation pattern, and miniaturization – that emerging technologies necessitate. This has fueled an explosive interest in bio-inspired antenna designs, a paradigm shift drawing inspiration from the ingenious structural solutions found in the living and non-living world, from plant leaves to bird feathers. These bio-inspired designs offer distinct advantages such as broader bandwidth and reduced sizes, making them highly appealing alternatives to the limitations of conventional antenna designs. This review explores a diverse range of bio-inspired designs. Among them are fractal geometries, inspired by self-repeating patterns in nature, which achieve optimal performance. Numerous designs in this category draw inspiration from nature, incorporating patterns observed in snowflakes, tree branches, clouds, and butterflies. Furthermore, nano-antennas have attracted significant attention for their vast potential applications in microwave and optical frequencies, playing a pivotal role in high-resolution spectroscopy, biomedical diagnosis and sensing, quantum photonics, and solar cell applications. By examining design methodologies and potential benefits, this article highlights the transformative potential of nature-inspired antennas. The compelling advantages of bio-inspired approaches necessitate a thorough exploration of their potential, paving the way for the development of next-generation communication systems with unprecedented capabilities.

  • Review of Segmentation Methods for Coastline Detection in SAR Images
    • Marcin Ciecholewski
    2024 Pełny tekst ARCHIVES OF COMPUTATIONAL METHODS IN ENGINEERING

    Synthetic aperture radar (SAR) images acquired by airborne sensors or remote sensing satellites contain the necessary information that can be used to investigate various objects of interest on the surface of the Earth, including coastlines. The coastal zone is of great economic importance and is also very densely populated. The intensive and increasing use of coasts and changes of coastlines motivate researchers to try to assess the pace of these changes. As remote sensing develops, coastlines are detected using various image processing and analysis methods, including segmentation methods. Segmentation is to allow separating water and land areas in order to obtain contours representing the shorelines of coasts. Its result has direct impact on the accuracy of the obtained contours and is one of the most important steps in image processing. This article presents an overview of state-of-the-art segmentation methods used for detecting and extracting coastlines from SAR images, taking into account the evaluation metrics used in them. Segmentation methods can be divided into three main groups: thresholding methods, active contours, and machine learning approaches. This article presents the theoretical and practical properties of individual groups of segmentation methods, their advantages and disadvantages, and also promising research directions. This article is intended to give researchers insight into existing approaches and to help them propose new, better solutions

  • Review—Advances in Rechargeable Lithium-Ion Batteries Utilizing Polyoxometalate-Functionalized Nanocarbon Materials
    • Samaneh Shahsavarifar
    • Morteza Rezapour
    • Mehdi Mehrpooya
    • Teofil Jesionowski
    • Rafael Luque
    2024 JOURNAL OF THE ELECTROCHEMICAL SOCIETY

    Polyoxometalates (POMs) are inorganic nanoclusters that consist of oxygen and transition metals. These nanoclusters serve as excellent precursors for creating electrode materials that contain transition metals. Additionally, the interaction between POMs and carbon substrates produces positive synergistic effects. There has been considerable attention on employing POMs and carbon nanostructures (for example carbon nanotubes, graphene, and mesoporous carbon) in composite materials for diverse purposes including catalysis, transformation, storage of energy, molecular detection, and electrical detection. By combining the reactive nature of POMs with the exceptional electrical properties of carbon nanostructures, highly desirable composite features can be achieved. This review delves into the extensive use of POM/nanocarbon materials for constructing rechargeable lithium-ion batteries, providing an in-depth analysis of the characteristics of POMs and the techniques employed for binding carbon.

  • Revision of architectural design education in terms of sustainability, creativity and digitalisation
    • Karolina Życzkowska
    • Špela Hudnik
    2024 Pełny tekst Global Journal of Engineering Education

    The article explores different educational strategies in relation to architectural design courses, focusing on sustainability, creativity and digitalisation. The starting point for this research was a t-survey (t-teachers) among 40 teachers of architectural design from eight European universities, to examine different programme frames and the teachers’ attitude versus the design process. The survey findings facilitated the identification of two fundamentally contrasting programme models, one at Gdańsk University of Technology (Gdańsk Tech), Poland, and the other at Ljubljana University, Slovenia. These models were subjected to detailed comparison, along with the corresponding teaching methods, based on a proposed universal model of the design process. Finally, a fusion of approaches was proposed and implemented in an intensive workshop, called There is no Planet B, conducted at Gdańsk Tech in 2022. Results of the workshop were verified through an s-survey (s-students) conducted among 20 participants of the course, pointing to the value of performance in the development of creative skills and participatory design, and the potential of the video format for public debate on sustainability.

  • Revisiting serotonin’s role in spatial memory: A call for sensitive analytical approaches
    • Paulina Kaźmierska-Grębowska
    • Witold Żakowski
    • Dorota Myślińska
    • Ravindra Sahu
    • Maciej Jankowski
    2024 Pełny tekst INTERNATIONAL JOURNAL OF BIOCHEMISTRY & CELL BIOLOGY

    The serotonergic system is involved in various psychiatric and neurological conditions, with serotonergic drugs often used in treatment. These conditions frequently affect spatial memory, which can serve as a model of declarative memory due to well-known cellular components and advanced methods that track neural activity and behavior with high temporal resolution. However, most findings on serotonin's effects on spatial learning and memory come from studies lacking refined analytical techniques and modern approaches needed to uncover the underlying neuronal mechanisms. This In Focus review critically investigates available studies to identify areas for further exploration. It finds that well-established behavioral models could yield more insights with modern tracking and data analysis approaches, while the cellular aspects of spatial memory remain underexplored. The review highlights the complex role of serotonin in spatial memory, which holds the potential for better understanding and treating memory-related disorders.

  • Revisiting Supervision for Continual Representation Learning
    • Daniel Marczak
    • Sebastian Cygert
    • Tomasz Trzciński
    • Bartłomiej Twardowski
    2024

    "In the field of continual learning, models are designed to learn tasks one after the other. While most research has centered on supervised continual learning, there is a growing interest in unsupervised continual learning, which makes use of the vast amounts of unlabeled data. Recent studies have highlighted the strengths of unsupervised methods, particularly self-supervised learning, in providing robust representations. The improved transferability of those representations built with self-supervised methods is often associated with the role played by the multi-layer perceptron projector. In this work, we depart from this observation and reexamine the role of supervision in continual representation learning. We reckon that additional information, such as human annotations, should not deteriorate the quality of representations. Our findings show that supervised models when enhanced with a multi-layer perceptron head, can outperform self-supervised models in continual representation learning. This highlights the importance of the multi-layer perceptron projector in shaping feature transferability across a sequence of tasks in continual learning. The code is available on github."

  • RF Input-Quasi-Reflectionless Dispersive-Delay Structures Based on Complementary-Diplexer Circuits
    • Maciej Jasiński
    • Adam Lamęcki
    • Roberto Gómez-García
    • Michał Mrozowski
    2024

    A class of RF dispersive-delay structures (DDSs) with input-quasi-reflectionless behavior is reported. It is based on the exploitation of complementary-diplexer circuit networks, in which the out-of-band RF-input-power echoes reflected by the main bandpass-filter-(BPF)-type channel are dissipated by the resistively-terminated auxiliary bandstop-filter-(BSF)-type channel. Specifically, it is shown that the influence of the absorptive auxiliary channel over the in-band transmission-phase response of the main channel can be compensated to obtain the desired transmission-phase profile in the overall RF device. Thus, a multi-functional RF component with co-integrated DDS, BPF, and low-RF-input-reflection capabilities can be designed. Optimization-based synthesis examples at the coupling-routing-diagram level of third-and fifth-order input-quasi-reflectionless BPF-based DDSs, for which the in-band group-delay pattern increases linearly with frequency, are presented. Moreover, for practical-validation purposes, a 2-GHz microstrip prototype is built and measured.

  • Rhodotorulic Acid and its Derivatives: Synthesis, Properties, and Applications
    • Joanna Stefaniak-Skorupa
    • Michał Nowak
    • Andrzej Skwarecki
    2024 CURRENT MEDICINAL CHEMISTRY

    Siderophores are low molecular weight compounds produced by microorganisms to scavenge iron in iron-deficient environments. Rhodotorulic acid (RA), a natural hydroxamate siderophore, plays a vital role in iron acquisition for fungi and bacteria. As the simplest natural hydroxamate siderophore, RA exhibits a high affinity for ferric ions, enabling it to form stable complexes that facilitate iron uptake and transport within microorganisms. Insights into RA derivatives reveal distinct biological effects and applications, with potential in various fields, from antioxidants to antifungals. Rhodotorulic acid and its derivatives show promise for novel therapies, plant protection strategies, and iron supplementation in agriculture. Understanding their properties could advance science and medicine with sustainable practices.

  • Risk Assessment at Unsignalized Intersections Based on Human-Road-Environment-Vehicle System Applying Fuzzy Logic
    • Ievgen Medvediev
    • Dmitriy Muzylyov
    • Vitalii Ivanov
    • Jakub Montewka
    • Justyna Trojanowska
    2024

    The constant increase in motorization level and traffic density increases risks due to dangerous situations for road participants. Therefore, assessing the accident level of road network elements has been an urgent task over the past decades. However, existing approaches mainly rely on traffic flow parameters and account for dynamic vehicle characteristics. The research aims to design a model accounting for uncertain factors (weather conditions and pedestrian wear color) that directly impact the accident rate. For this, the mathematical toolkit of fuzzy logic is used. The study presented in this paper has yielded a model for assessing accident risk at unsignalized intersections. This model, known as the Fuzzy Model, considers various factors such as human behavior, road conditions, environmental factors, and vehicle characteristics. The model proposes accounting for the factors included in the four subsystems (Human-Road-Environment-Vehicle) that determine the transport mega system. Fuzzy Logic MATLAB Toolbox was used for modeling, and the model was assembled using Simulink Environment tools. The simulation used a full-factor experiment 34 for four factors at three variation levels for each parameter. A set of accident risk factors was obtained for 81 conducted tests. Based on the modeling, a 3-level table of accident risk measurement was formed at unsignalized intersections depending on the pedestrian's clothing color, intersection equipment level (illumination), weather conditions, and vehicle speed. The study results are due to a novel accident risk system that can be used for operational measures to increase safety levels at an unsignalized intersection.

  • Risk Assessment Due To Customs Delays In Supply Chains By Fuzzy Logic
    • Ievgen Medvediev
    • Dmitriy Muzylyov
    • Jakub Montewka
    2024

    Due to violations of existing trade relations, cargo flows between the European Union and Ukraine have been redistributed. As a result, new supply chains have been created that have increased the tension on ground transport, including road and rail. Unfortunately, this has caused significant delays when crossing the border, which has led to a greater increase in the total delivery time of goods. Therefore, to plan for effective delivery, it is important to consider risks associated with increased border passing time. A detailed study of the challenge revealed that these risks are caused by various hazards, which are often fuzzy. To address these risks, a modern mathematical approach is required. Fuzzy logic has proven to be successful in dealing with such research questions. According to the above, this study aims to design a fuzzy model that proactively assesses the risks of customs delays caused by operational, technical, human, and political hazards when crossing borders. The study identified four categories of hazards that can lead to delays or refusals in customs operations, resulting in increased border crossing times. These hazards are technical failures of the control system, border blocking due to human factors, formation of a queue for technological failures, and political influence. The proposed approach can take into account both quantitative and non-quantitative threats arising at the border. The study resulted in a decision support system that allows carriers to calculate possible risks and select the best alternative border crossing point in advance, reducing the risk of supply chain disruptions due to customs waivers.

  • Risk factor assessment in agricultural supply chain by fuzzy logic
    • Dmitriy Muzylyov
    • Ievgen Medvediev
    • Olexiy Pavlenko
    2024

    Significant uncertainty characterizes the harvest period. This aspect is due to various risks impacting agrifood supply chains. The occurrence of risks is due to hazards: technological failures, technical breakdowns, or adverse weather conditions. Hence, the operational time of the agricultural supply chain during the harvest period increases due to such risk factors. In essence, some hazards are fuzzy, and the nature of most threats is characterized by significant uncertainty. Classical risk assessment methods do not allow assessing simultaneously the impact of various risks, especially those expressed fuzzy (weather conditions). Therefore, the study objective is to design a fuzzy model assessing risk factors that impact the increase in the operating time of the agrifood supply chain during the harvest period. As initial parameters in the indistinct model, three groups of risk factors were accepted: weather conditions, technological failures and technical malfunctions. The MATLAB Fuzzy Toolbox is used to design the fuzzy model, and the model architecture is implemented in Simulink. The modelling results can be used to create the necessary reserves of the harvesting and transport complex to ensure timely harvesting and reduce the negative impact of hazards on the agricultural supply chain operating.