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Gdańsk University of Technology

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  • 5G Millimeter Wave Network Optimization: Dual Connectivity and Power Allocation Strategy
    • Abdulhalim Fayad
    • Tibor Cinkler
    • Jacek Rak
    2023 Full text IEEE Access

    The fifth generation (5G) of mobile networks utilizing millimeter Wave (mmWave) bands can be considered the leading player in meeting the continuously increasing hunger of the end user demands in the near future. However, 5G networks are characterized by high power consumption, which poses a significant challenge to the efficient management of base stations (BSs) and user association. Implementing new power consumption and user association strategies is imperative to address this issue. For that in this work, we focus on the Dual Connectivity-User and Power Allocation (DC-UPA) problem utilizing BS switching on/off along with user dual connectivity. The problem is mathematically formulated as an Integer Linear Program (ILP), and its NP-hardness is proven by showing its equivalence to a variant of the set covering problem. Moreover, we developed two heuristic algorithms: Simulated Annealing (SA) and Distance-Aware (DA) greedy, to mitigate the impact of the problem complexity and resolve the ILP scalability issue. We conducted extensive simulations to validate the effectiveness of the proposed heuristics in a two-dimensional area containing multiple BSs and users with uniform and nonuniform geographical distributions. The performance of the SA and DA algorithms was compared against the ILP approach. We evaluated the performance of the proposed solutions considering different aspects such as the number of users, the BS radius, and the traffic load changes. The numerical results show that SA outperforms the DA in both uniform and nonuniform geographical distributions of users. The SA provides a sub-optimal solution with an optimality gap of about 3.2%, while the optimality gap of the DA is 8.62% in the case of the uniform distribution. Moreover, the optimality gap in the case of nonuniform distribution is equal to about 1% and 5.2% of SA and DA, respectively. Additionally, by utilizing our solutions, the reduction of the level of power consumption up to 16.1% and 20% in the case of uniform and nonuniform distributions can be achieved. The obtained results highlight the efficiency of the proposed algorithms in addressing the DC-UPA problem, providing practical solutions for managing power consumption and maintaining continuous user connectivity in 5G mmWave networks.

  • 5G/6G optical fronthaul modeling: cost and energy consumption assessment
    • Abdulhalim Fayad
    • Tibor Cinkler
    • Jacek Rak
    2023 Full text Journal of Optical Communications and Networking

    In fifth generation (5G) and the future beyond 5G (6G) radio access networks (RANs), the cost of fronthaul deployment is a main challenge for mobile network operators. Depending on different constraints, there are various solutions to deploy an efficient fronthaul. Fiber-optic-based fronthaul offers long-term support with regard to a rapid increase in capacity demands. When fiber connections, either point-to-point (P2P) or point-to-multipoint [i.e., passive optical networks (PONs)], are not available due to economic or geographical constraints, new optical fronthaul solutions such as free space optics (FSO) can be applied. Before deploying any optical fronthaul architecture, mobile operators must assess its impact on the total cost of ownership (TCO) of the network (i.e., capital and operational expenditures). To assist operators in choosing the most cost-effective fronthaul architecture, in this paper, we show how to evaluate the TCO of 5G and beyond RANs while taking various fronthaul architectures (P2P, PON, and hybrid PON-FSO) into consideration. Furthermore, this paper answers the question of how much energy is needed to run a network using each of the considered optical fronthaul architectures. To do so, we propose a holistic framework based on an integer linear program that minimizes the TCO of the network. Furthermore, we propose a heuristic algorithm to solve large-sized problems. We run simulations to compare different fronthaul architectures for two deployment areas: dense and sparse.

  • A Bayesian regularization-backpropagation neural network model for peeling computations
    • Saipraneeth Gouravaraju
    • Jyotindra Narayan
    • Roger Sauer
    • Sachin Singh Gautam
    2023 Full text JOURNAL OF ADHESION

    A Bayesian regularization-backpropagation neural network (BRBPNN) model is employed to predict some aspects of the gecko spatula peeling, viz. the variation of the maximum normal and tangential pull-off forces and the resultant force angle at detachment with the peeling angle. K-fold cross validation is used to improve the effectiveness of the model. The input data is taken from finite element (FE) peeling results. The neural network is trained with 75% of the FE dataset. The remaining 25% are utilized to predict the peeling behavior. The training performance is evaluated for every change in the number of hidden layer neurons to determine the optimal network structure The relative error is calculated to draw a clear comparison between predicted and FE results. It is shown that the BR-BPNN model in conjunction with the k-fold technique has significant potential to estimate the peeling behavior.

  • A BODIPY‐Based Molecular Rotor in Giant Unilamellar Vesicles: A Case Study by Polarization‐Resolved Time‐Resolved Emission and Transient Absorption Spectroscopy
    • Keshav Kumar Jha
    • Amrutha Prabhakaran
    • Lukas Spantzel
    • Rengel Cane Sia
    • Iván Pérez
    • Ruben Arturo Arellano-Reyes
    • Anna Elmanova
    • Anindita Dasgupta
    • Christian Eggeling
    • Michael Börsch
    • Julien Guthmuller
    • Martin Presselt
    • Tia E. Keyes
    • Benjamin Dietzek-Ivanšić
    2023 Full text ChemPhotoChem

    BODIPY and BODIPY-derived systems are widely applied as fluorophores and as probes for viscosity detection in solvents and biological media. Their orientational and rotational dynamics in biological media are thus of vital mechanistic importance and extensively investigated. In this contribution, polarization-resolved confocal microscopy is used to determine the orientation of an amphiphilic BODIPY-cholesterol derivative in homogeneous giant unilamellar vesicles (GUV) made from 1,2- dioleoyl-sn-glycero-3-phosphocholine (DOPC). The BODIPY-moiety of the molecule is placed near the polar head groups, and the cholesterol moiety is embedded in the membrane along the acyl chain of the lipids. The rotational relaxation of fluorophore is conventionally investigated by time-resolved emission anisotropy (TEA); and this method is also used here. However, TEA depends on the emission of the fluorophore and may not be useful to probe rotational dynamics of the nonemissive triplet states. Thus, we employ femtosecond transient absorption anisotropy (TAA), that relies on the absorption of the molecule to complement the studies of the amphiphilic BODIPY in DCM and GUV. The photoinduced anisotropy of the BODIPY molecule in DCM decays tri-exponentially, the decay components (sub-5 ps, 43 ps and 440 ps) of anisotropy are associated with the non-spherical shape of the BODIPY molecule. However, the anisotropy decay in homogenous GUVs follows a biexponential decay; which arises from the wobblingin-a-cone motion of the non-spherical molecule in the high viscous lipid bilayer media. The observations for the BODIPYchol molecule in the GUV environment by TAA will extend to the investigation of non-emissive molecules in cellular environment since GUV structure and size resembles the membrane of a biological cell.

  • A brief note on entire fracture surface topography parameters for 18Ni300 maraging steel produced by LB-PBF after LCF
    • Wojciech Macek
    • Ricardo Branco
    • Przemysław Podulka
    • Mateusz Kopec
    • Shun-Peng Zhu
    • José Domingos Costa
    2023 ENGINEERING FAILURE ANALYSIS

    The concept of entire fracture surface investigation is helpful in explaining fatigue phenomena. In this paper, this method has been applied for 18Ni300 maraging steel using a 3D measurement system. Before post-mortem analysis, the specimens produced by laser beam powder bed fusion (LB-PBF) were tested under low-cycle fatigue (LCF) for eight strain amplitudes in the interval 0.3% to 1.0%. The attention was placed on the relationship between the fatigue features, represented by the strain level and the fatigue life as well as the fracture surface topography evaluated in the form of areal, volume and fractal dimension parameters. It was found that fatigue life predictions calculated using the core material volume Vmc, obtained with the entire fracture surface method were within a scatter band with factors of ±1.5. The present results can be useful for the analysis of damaged structural elements exposed to LCF, especially for materials produced by additive manufacturing (AM). The outcomes of this brief note are important for the development of other fractographic methods and validation of fatigue life evaluation procedures.

  • A CNN based coronavirus disease prediction system for chest X-rays
    • Umair Hafeez
    • Muhammad Umer
    • Ahmad Hameed
    • Hassan Mustafa
    • Ahmed Sohaib
    • Michele Nappi
    • Hamza Madni
    2023 Journal of Ambient Intelligence and Humanized Computing

    Coronavirus disease (COVID-19) proliferated globally in early 2020, causing existential dread in the whole world. Radiography is crucial in the clinical staging and diagnosis of COVID-19 and offers high potential to improve healthcare plans for tackling the pandemic. However high variations in infection characteristics and low contrast between normal and infected regions pose great challenges in preparing radiological reports. To address these challenges, this study presents CODISCCNN (CNN based Coronavirus DIsease Prediction System for Chest X-rays) that can automatically extract the features from chest X-ray images for the disease prediction. However, to get the infected region of X-ray, edges of the images are detected by applying image preprocessing. Furthermore, to attenuate the shortage of labeled datasets data augmentation has been adapted. Extensive experiments have been performed to classify X-ray images into two classes (Normal and COVID), three classes (Normal, COVID, and Virus Bacteria), and four classes (Normal, COVID, and Virus Bacteria, and Virus Pneumonia) with the accuracy of 97%, 89%, and 84% respectively. The proposed CNN-based model outperforms many cutting-edge classifcation models and boosts state-of-the-art performance.

  • A commonly-accessible toolchain for live streaming music events with higher-order ambisonic audio and 4k 360 vision
    • Bartłomiej Mróz
    • Piotr Odya
    • Przemysław Danowski
    • Marek Kabaciński
    2023 Full text

    An immersive live stream is especially interesting in the ongoing development of telepresence tools, especially in the virtual reality (VR) or mixed reality (MR) domain. This paper explores the remote and immersive way of enabling telepresence for the audience to high-fidelity music performance using freely-available and easily-accessible tools. A functional VR live-streaming toolchain, comprising 360 vision and higher-order ambisonic audio, is presented and described in detail. Two separate recordings with two different approaches are outlined. The results gathered from the audiences' impressions are discussed. Finally, possible improvements to the immersive live streaming and recording processes were discussed.

  • A Compact Self-Hexaplexing Antenna Implemented on Substrate-Integrated Rectangular Cavity for Hexa-Band Applications
    • Rusan Kumar Barik
    • Sławomir Kozieł
    2023 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS

    This brief introduces a novel architecture of a compact self-hexaplexing antenna (SHA) implemented on a substrate-integrated rectangular cavity (SIRC) for hexa-band applications. The proposed SHA is configured by using an SIRC resonator, two Pi-shaped slots (PSSs), and six 50Ω microstrip feedlines. The PSSs are connected back-to-back and loaded on top of the SIRC resonator to produce six patch radiators (PRs). The PRs are excited by 50Ω feedlines to radiate at six operating bands with self-multiplexing characteristics. The operating bands are tunable. A particular band can be adjusted independently based on the system requirement without altering the other operating bands. A comprehensive parametric study is carried out to allow a suitable band tunability, high isolation, and matching at the ports. For validation, an SIRC-based SHA radiating at 2.29, 2.96, 4.3, 5.0, 5.61, and 6.18 GHz is fabricated and experimentally demonstrated. The proposed SHA allows us to achieve a compact size of 0.173λg2, which is the smallest among the self-quadruplexing antennas and self-multiplexing antennas reported in the literature thus far. Additionally, it exhibits high isolation of 27 dB, hexa-band operation, a tunability range from 2.2 GHz to 8 GHz, along with measured gains greater than 3.73 dBi.

  • A comparative study of pentanol (C5 alcohol) and kerosene blends in terms of gas turbine engine performance and exhaust gas emission
    • Tomasz Suchocki
    • Paweł Kazimierski
    • Piotr Lampart
    • Katarzyna Januszewicz
    • T. Białecki
    • Bartosz Gawron
    • A. Janicka
    2023 FUEL

    The growing demand for sustainable and clean energy sources provides the incentive for the development of alternative fuels. Simultaneously, the development of gas turbine technologies with flexible fuel supply systems enables the use of alternative non-fossil fuels that can play key roles in contributing to global efforts in meeting emissions targets. This paper presents the current state of knowledge on the production and potential use of pentanol (C5 alcohol) in diesel engines and gas turbines. The combustion performance of a GTM-140 jet engine supplied by mixtures of pentanol with aviation kerosene is then evaluated and the results are compared with those of kerosene mixtures with other biofuels – propanol (C3 alcohol)) and butanol (C4 alcohol)). All the investigated liquid biofuel alternatives showed potential for reducing regulated emissions such as NOX (on average by 40%) and CO (on average by 25%) for C5 alcohol. The increase in the proportion of pentanol in the blends has the effect of reducing the temperature downstream of the combustion chamber on average by 5.8% for Turbine Inlet Temperature (TIT) and 6.1% for Exhaust Gas Temperature (EGT). The jet engine fuel efficiency expressed as thrust specific fuel consumption (TSFC) for all tested biofuels decreased on average by 40% for C5 alcohol. The use of alternative fuels such as bio-alcohols offers real opportunities for cleaner and more envi- ronmentally friendly gas turbine operation in aviation and power generation.

  • A comprehensive approach to SBR modelling for monitoring and control system design
    • Tomasz Ujazdowski
    • Tomasz Zubowicz
    • Robert Piotrowski
    2023 Journal of Water Process Engineering

    The aim of this research is to provide a comprehensive description of the Sequencing Batch Reactor (SBR) modelling for monitoring, control, and plant operational optimisation validation. The paper provides a detailed modelling of the SBR, its components and constituent processes. For this purpose, the mass balance principle and continuity equations were provided with a reactive term implemented using Activated Sludge Model (ASM). The spatially discretised models (along the vertical axis) are then used in numerical experiments. Simulations performed enable comparison of the impact of different models of activated sludge settling velocity, as well as two different approaches to modelling reactions in the SBR. The latter was achieved by using the ASM2d and ASM3-BioP extended with an enzyme group modelling the lag phase observed in microorganisms during a rapid change in environmental conditions. The presented results have been obtained using the model of the SBR at Swarzewo in the North of Poland.

  • A comprehensive lipidomic analysis of oilseeds using LC-Q-TOF-MS and dispersive micro-solid phase (D-μ-SPE) extraction techniques
    • Inal Bakhytkyzy
    • Weronika Hewelt-Belka
    • Agata Kot-Wasik
    2023 JOURNAL OF FOOD COMPOSITION AND ANALYSIS

    Growing public health awareness increased the demand for natural products with positive health benefits. Vegetable oils containing omega-3 fatty acids (FA) such as alpha-linolenic acid (ALA) has been proposed as a possible source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In this work, a comprehensive lipidome analysis and comparison of seven oilseeds, including flaxseed, chia, hemp, black cumin, white sesame, black sesame and poppy using dispersive micro-solid phase extraction (D-μ-SPE) coupled with liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) was performed. The detailed characterisation of oilseed lipid profiles was presented. The identified lipid classes included lysophosphatidylcholines (LPC) and lysophosphatidylethanolamine (LPE), glycerophosphatidylcholines (PC) and glycerophosphatidylethanolamines (PE), diacylglycerols (DG), and triacylglycerols (TG). Multivariate data analysis demonstrated that flax, hemp, and chia seeds were very similar in their lipid content. These seeds contained higher amounts of lipids with less saturated FA substituents, while black cumin, black and white sesame samples shared similar lipid composition with more saturated FA substituents. ALA and linoleic acid (LA) were present in all detected classes of lipids

  • A Comprehensive Review of Phytonutrients as a Dietary Therapy for Obesity
    • Shahida Anusha Siddiqui
    • Iskandar Azmy Harahap
    • Priyanka Suthar
    • Yuan Seng Wu
    • Nibedita Ghosh
    • Roberto Castro Munoz
    2023 Full text Foods

    Obesity is a complex medical condition mainly caused by eating habits, genetics, lifestyle, and medicine. The present study deals with traditional diets like the Mediterranean diet, Nordic diet, African Heritage diet, Asian diet, and DASH, as these are considered to be sustainable diets for curing obesity. However, the bioavailability of phytonutrients consumed in the diet may vary, depending on several factors such as digestion and absorption of phytonutrients, interaction with other substances, cooking processes, and individual differences. Hence, several phytochemicals, like polyphenols, alkaloids, saponins, terpenoids, etc., have been investigated to assess their efficiencies and safety in the prevention and treatment of obesity. These phytochemicals have anti-obesity effects, mediated via modulation of many pathways, such as decreased lipogenesis, lipid absorption, accelerated lipolysis, energy intake, expenditure, and preadipocyte differentiation and proliferation. Owing to these anti-obesity effects, new food formulations incorporating these phytonutrients were introduced that can be beneficial in reducing the prevalence of obesity and promoting public health.

  • A comprehensive review on Ginger (Zingiber officinale) as a potential source of nutraceuticals for food formulations: Towards the polishing of gingerol and other present biomolecules
    • Clarissa Garza-Cadena
    • Daniela Marian Ortega-Rivera
    • Gerson Machorro-García
    • Eloy Mauricio Gonzalez-Zermeño
    • Diego Homma-Dueñas
    • Maksymilian Plata-Gryl
    • Roberto Castro-Muñoz
    2023 Full text FOOD CHEMISTRY

    Currently, ginger is one the most consumed plants when dealing with the treatments of various illnesses. So far, it is known that various biologically active molecules, such as gingerols, shogaols and zingerone, among others, are the main responsible for specific biological activities, opening a new window for its utilization as a nutraceutical in foods. In pioneering extraction processes, solvent extraction has been initially used for these applications; however, the drawbacks of this typical extraction method compared with other emergent separation techniques make it possible for the exploration of new extraction pathways, including microwave, ultrasound, supercritical, subcritical and pressurized-assisted extraction, along with three phase partitioning, high-speed counter current chromatography and magnetic solid phase extraction. To the best of our knowledge, there is no report documenting the recent studies and cases of study in this field. Therefore, we comprehensively review the progress and the latest findings (over the last five years) on research developments, including patents and emerging extraction methods, aiming at the purification of biologically active molecules (gingerols, shogaols and zingerone) contained in ginger. Over the course of this review, particular emphasis is devoted to breakthrough strategies and meaningful outcomes in ginger components extraction. Finally, dosage and safety concerns related to ginger extracts are also documented.

  • A Computational Analysis of the Aerodynamic and Aeromechanical Behavior of a Thermo-Well for Steam Temperature Measurement in a Steam Turbine
    • Mariusz Banaszkiewicz
    • Janusz Badur
    • Sebastian Kornet
    • Daniel Sławiński
    • Bartosz Kraszewski
    • Paweł Ziółkowski
    • Anna Rehmus-Forc
    • Grzegorz Bzymek
    2023 HEAT TRANSFER ENGINEERING

    The goal of the paper is twofold: firstly, it presents computational fluid dynamics analysis for finding maximum unsteady flow forces (and their frequencies) acting on a thermo-well for measuring steam temperature in a steam turbine control stage and secondly, it presents computational solid dynamics analysis of possibility of entry into resonance of the thermowell structure. There have been analyzed two cases of flow with changing temperature, pressure, and mass flow rate in the control stage chamber of a turbine high-pressure cylinder. The problem is also described in the ASME standard PTC19.3 TW-2010 providing detailed guidelines for thermo-well calculations. The problem under consideration is only a part of whole technical analysis and obeys a primary hypothesis that a reason of the thermo-well damage was a resonance phenomenon.

  • A Concept for Safe and Less Expensive Acceleration of a Marine Steam Turbine Start-up
    • Mateusz Bryk
    • Jerzy Głuch
    2023 Journal of Marine Science and Application

    This paper analyses the issue of accelerated start-up of a marine steam turbine, which is an important problem because the start-up of a steam machine involves the combustion of fuel that is not transformed into useful energy. To find novel technologies that offer improvements in this aspect is essential due to restrictions on reducing ship emissions. Thus, the shorter the start-up time, the better for the environment and economy. High-pressure (HP) part of the turbine originally located on the Queen Elizabeth II unit was analysed. Advanced numerical calculations by thermal fluid-solid-interaction (Thermal FSI) were carried out. A series of simulations were performed for the accelerated start-up with controlled steam injection. A description of the chosen calculation methodology and the results obtained by simulation are included in this paper. The stress occurring during the accelerated start-up are approximately 40 MPa higher than those during the reference start-up. The relative elongations between the rotor and the hull during accelerated start-up reach a maximum value of 0.89 mm (0.83 mm for ultra-fast start-up). Reducing the steam turbine start-up time by 75% results in a 36.7 tons reduction in fuel consumption for start-up, resulting in an annual savings of 5 372 USD. In conclusion, the concept proposed by the authors is safe, less expensive and does not affect the life of the turbine. In addition, results and applications from Siemens prove that additional injection of cooling steam is possible.

  • A convergence result for mountain pass periodic solutions of perturbed Hamiltonian systems
    • Marek Izydorek
    • Joanna Janczewska
    • Pedro Soares
    2023 Full text COMMUNICATIONS IN CONTEMPORARY MATHEMATICS

    In this work, we study second-order Hamiltonian systems under small perturbations. We assume that the main term of the system has a mountain pass structure, but do not suppose any condition on the perturbation. We prove the existence of a periodic solution. Moreover, we show that periodic solutions of perturbed systems converge to periodic solutions of the unperturbed systems if the perturbation tends to zero. The assumption on the potential that guarantees the mountain pass geometry of the corresponding action functional is of independent interest as it is more general than those by Rabinowitz [Homoclinic orbits for a class of Hamiltonian systems, Proc. R. Soc. Edinburgh A 114 (1990) 33–38] and the authors [M. Izydorek and J. Janczewska, Homoclinic solutions for a class of the second-order Hamiltonian systems, J. Differ. Equ. 219 (2005) 375–389].

  • A critical review on electrospun membranes containing 2D materials for seawater desalination
    • Roberto Castro-Muñoz
    2023 DESALINATION

    Electrospun nanofibers are a cutting-edge class of membranes which have been applied in several molecular separations. These membranes can be well designed and tailored due to the versatility of the electrospinning process. Eminently, electrospun membranes, once implemented in membrane processes, are an alternative in removing salts and some other minerals from water, so-called desalination, for producing drinking water. Such membranes present unique properties over traditional membranes, such as outstanding performance thanks to the high porosity, adjustable pore size, and functionalized surface of the nanofibrous. Today, electrospun membranes are denominated as a “hot” topic in research for desalination purposes in which mainly polymer phases are used in membrane fabrication, however, a current trend deals with the doping of such polymer phases with two-dimensional (2D) materials, such as graphene, graphene oxide, MXene, boron and carbon nitrides, among others. Apart from their extraordinary physical and chemical properties, these latter materials exhibited unprecedented water transport rates, making them suitable for preparing more attractive membranes for desalination. Therefore, the aim of this comprehensive review is to reveal the latest advances in electrospun membranes containing 2D materials. Particular emphasis has been devoted to the reports published over the last two years, from 2020 up to now. In this review, apart from reporting the breakthroughs in membrane preparation and their desalination performance data, the main advantages and drawbacks of the developed membranes are elucidated. Finally, after analysing the recent literature, tentative research gaps and recommendations to the new researchers in the field are also stated.

  • A Diagnostic Method Based on Deflection Analysis for Monitoring Post-elastic Response of Beams
    • Adam Ścięgaj
    2023 Full text International Journal of Civil Engineering

    A non-destructive diagnostic method based on deflection analysis for monitoring the post-elastic response of beams was developed, and a diagnostic indicator was proposed. The indicator was defined as the second moment of the normalised curvature function about the mid-span, where the curvature was computed from the normalised deflection function. Elastic reference values of the indicator were computed for simply supported beams under uniformly distributed load, three-point, and four-point bending. Development of the indicator under progressive loading was examined with the help of finite element analyses. The indicator value monotonically decreased with increasing deformation provided that maximum bending moment was located between 0.41L and 0.59L, where L is the span of the beam. In this interval, the value of the indicator was unique and enabled the direct monitoring of the post-elastic stress level in the cross-section. The method was validated with the help of available experiments on simply supported beams. For beams working in the elastic range, a mean error of 2:1% was obtained between the measured and theoretical indicator values. For quasi-brittle material in the post-elastic stage, the decreasing value of the indicator signified the development of damage in accordance with experi- mental results.

  • A facile strategy for reclaiming discarded graphite and harnessing the rate capabilities of graphite anodes
    • Honghong Tian
    • Magdalena Graczyk-Zajac
    • Dario M. De Carolis
    • Chuanmu Tian
    • Emmanuel III Ricohermoso
    • Zhiwu Yang
    • Wei Li
    • Monika Wilamowska-Zawłocka
    • Jan P. Hofmann
    • Anke Weidenkaff
    • Ralf Riedel
    2023 Full text JOURNAL OF HAZARDOUS MATERIALS

    Graphite negative electrodes are unbeaten hitherto in lithium-ion batteries (LiBs) due to their unique chemical and physical properties. Thus, the increasing scarcity of graphite resources makes smart recycling or repurposing of discarded graphite particularly imperative. However, the current recycling techniques still need to be improved upon with urgency. Herein a facile and efficient hydrometallurgical process is reported to effectively regenerate aged (39.5 %, 75 % state-of-health, SOH) scrapped graphite (SG) from end-of-life lithium-ion bat- teries. Ultimately, the first cycle reversible capacity of SG1 (SOH = 39.5 %) improved from 266 mAh/g to 337 mAh/g while 330 mAh/g (98 %) remain after 100 cycles at 0.5 C. The reversible capacity for the first cycle of SG2 (SOH = 75 %) boosted from 335 mAh/g to 366 mAh/g with the capacity retention of 99.3 % after 100 cycles at 0.5 C, which is comparable with the benchmark commercial graphite. The regenerated graphites RG1 and RG2 exhibit excellent output characteristics even increasing the rate up to 4 C. This is the best rate level reported in the literature to date. Finally, the diffusion coefficient of Li ions during deintercalation and intercalation in the regenerated graphites have been measured by galvanostatic intermittent titration technique (GITT), determining values 2 orders-of-magnitude higher than that of the spent counterparts. Taking advantage of the synergistic effect of acid leaching and heat treatment, this strategy provides a simple and up-scalable method to recycle graphitic anodes.

  • A first-principles study of electronic and magnetic properties of 4d transition metals doped in Wurtzite GaN for spintronics applications
    • Omkar A. Shilkar
    • Rajendra Adhikari
    • Subrahmanyam Sappati
    • Shreya Godi
    • Ashish M. Desai
    2023 Full text JOURNAL OF MOLECULAR MODELING

    We studied the electronic and magnetic properties of wurtzite GaN (w-GaN) doped with different concentrations of the 4d transition metal ions Nb, Mo, and Ru. We incorporated spin-polarized plane-wave density functional theory within an ultrasoft pseudopotential formalism. The 4d transition metals were doped at different geometrical sites to determine the geometry with the lowest total energy and the one that induced the largest magnetization. A spin-spin interaction study was performed to determine whether the doped compound was ferromagnetic or antiferromagnetic. The origin of magnetization in the transition metal-doped w-GaN compounds is due to the p-d hybridization of the nitrogen and 4d transition metals. From the bulk modulus results, we inferred that the structural integrity is preserved under compressive loads after doping w-GaN with these 4D transition metal ions. Our results indicate that these compounds can be used in spintronic applications.

  • A Five-Leg Three-Level Dual-Output Inverter
    • Charles Odeh
    • Arkadiusz Lewicki
    • Marcin Morawiec
    • Joseph O. Ojo
    2023 Full text IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS

    Classical 3-level dual-output inverter, 3-L DOI, involves two similar 3-level inverters that provides a pair of 3-phase output voltages with same or different frequencies from common input voltage source. Flexibility of either operation of the constituting inverters is evident in this DOI; but total duplication of power switches is a major drawback. State of the art coupled 3-L DOIs reduce this drawback by providing series-shared power devices between the two different 3-phase output terminals. Compared with the classical 3-L DOI, these newly developed coupled 3-L DOIs involves a smaller number of power switches; however, independent operation of the constituting inverters is lost. In this brief, a 3-L DOI is proposed which involves lesser number of power devices and provides flexibility of either operation of the constituting inverters. The 3-L DOI feature hinges on the concept of parallel-common-inverter-leg representation. At the same or varying frequency mode operation, the proposed inverter can synthesize two 3-phase output voltages. Range and relation between the two modes of operations are defined for the DOI. The control strategy is based on the single triangular carrier sinusoidal pulse-width modulation perspective. Experimental results are presented that depict the DOI inverter performances.

  • A Formal Approach to Model the Expansion of Natural Events: The Case of Infectious Diseases
    • Maria Teresa Signes-Pont
    • Joan Boters Pitarch
    • Julian Szymański
    • Higinio Mora-Mora
    2023 Parallel Processing Letters

    A formal approach to modeling the expansion of natural events is presented in this paper. Since the mathematical, statistical or computational methods used are not relevant for development, a modular framework is carried out that guides from the external observation down to the innermost level of the variables that have to appear in the future mathematical-computational formalization. As an example we analyze the expansion of Covid-19. We perform a qualitative estimation of the impact of the causes on the delays of the spread and an analysis of the parameters.

  • A framework estimating the minimum sample size and margin of error for maritime quantitative risk analysis
    • Romanas Puisa,
    • Przemysław Krata
    • Jakub Montewka
    2023 Full text RELIABILITY ENGINEERING & SYSTEM SAFETY

    The average accident frequency is essential for quantitative risk analysis and is conventionally estimated from accident statistics. This paper has systematically synthesised the knowledge on statistical errors and offered the missing instructions, a framework, for determining the minimum sample size and the margin of error (MOE) when calculating the average accident frequency from an accident database at hand. We have applied this framework to representative accident datasets in the maritime domain and presented the revealing results that can already be used in QRAs based on these datasets. The findings are useful to both QRA analysts and policy makers. Interestingly, the framework application has revealed that the determined minimum sample sizes would exceed the datasets available in existing maritime casualty databases by decades, requiring at least 10% MOE to be factored into pertinent QRAs. By the same token, the earlier notable QRAs (developed as part of formal safety assessments in support of rule making) had to consider the MOE of over 30%, given the sample sizes used, likely shifting the conclusions they arrived at. Other findings of the application have shown that the average accident frequencies for large passenger ships have remained constant over the past 40 years.

  • A framework of open government data (OGD) e-service quality dimensions with future research agenda
    • Charalampos Harris Alexopoulos
    • Stuti Saxena
    • Nina Rizun
    • Shao Deo
    2023 Full text Records Management Journal

    Purpose This research paper aims to present a framework of open government data (OGD) relating to e-service quality dimensions. In addition, it provides a research agenda for the e-service delivery of OGD. Design/methodology/approach A literature review pertaining to e-service quality with special reference to e-government was delivered to deduce the key dimensions of e-service quality for OGD. Findings Five e-service quality dimensions of OGD are identified in the study; website design, fulfilment, service provision to the user while interfacing with the OGD Web portal, service provision to the user during and after the value-creation and innovation period and security/privacy. To further OGD re-use for value creation and innovation, it is important that the e-service quality dimensions are built into all OGD programmes by public authorities. Originality/value Hitherto, extant research has focused on the data quality dimensions of OGD, but the dimensions linked with e-service have not been explored. This study seeks to fill this gap and, in addition, suggests further research requirements in this field.

  • A Generalized Version of the Lions-Type Lemma
    • Magdalena Chmara
    2023 Full text Annales Mathematicae Silesianae

    In this short paper, I recall the history of dealing with the lack of compactness of a sequence in the case of an unbounded domain and prove the vanishing Lions-type result for a sequence of Lebesgue-measurable functions. This lemma generalizes some results for a class of Orlicz–Sobolev spaces. What matters here is the behavior of the integral, not the space

  • A Generative Approach to Hull Design for a Small Watercraft
    • Artur Karczewski
    • Janusz Kozak
    2023 Full text Polish Maritime Research

    In the field of ocean engineering, the task of spatial hull modelling is one of the most complicated problems in ship design. This study presents a procedure applied as a generative approach to the design problems for the hull geometry of small vessels using elements of concurrent design with multi-criteria optimisation processes. Based upon widely available commercial software, an algorithm for the mathematical formulation of the boundary conditions, the data flow during processing and formulae for the optimisation processes are developed. As an example of the application of this novel approach, the results for the hull design of a sailing yacht are presented.

  • A hybrid approach to optimization of radial inflow turbine with principal component analysis
    • Łukasz Witanowski
    • Paweł Ziółkowski
    • Piotr Klonowicz
    • Piotr Lampart
    2023 ENERGY

    Energy conversion efficiency is one of the most important features of power systems as it greatly influences the economic balance. The efficiency can be increased in many ways. One of them is to optimize individual components of the power plant. In most Organic Rankine Cycle (ORC) systems the power is created in the turbine and these systems can benefit from effective turbine optimization. The paper presents the use of two kinds of hybrid stochastic/deterministic methods for 3D blade shape optimization of a 10 kW single-stage radial inflow turbine (RIT) and compares the obtained results with those received from the stochastic or deterministic methods. Eight algorithms were used altogether, including one stochastic, three deterministic and four hybrid algorithms. Principal component analysis (PCA) was used to analyze the optimization process. 3D models of selected reference and optimized geometries were created to compare the differences in the obtained flow characteristics. At least two different geometries were found for which the efficiency increased by above 2 pp. (validated on refined grids). The increased efficiency was obtained over the entire investigated range of mass flow rate, with a value of the total-to-static efficiency of 90.6% at the nominal point obtained using a hybrid method.

  • A Low-Cost System for Far-Field Non-Anechoic Measurements of Antenna Performance Figures
    • Jan Olencki
    • Vorya Waladi
    • Adrian Bekasiewicz
    • Leifur Leifsson
    2023 Full text IEEE Access

    Prototype measurements are the key step in the development of antenna structures. Typically, their far-field characteristics are validated in expensive, dedicated facilities such as open range sites, or anechoic chambers. Despite being necessary for obtaining high-precision data (e.g., for device qualification), the use of costly infrastructure might not be fully justified when the main goal of measurements includes demonstration of the methodology behind determination of the performance figures of interest (e.g., for the purpose of teaching), or rough validation of the EM simulation model correctness. From this perspective, systems for far-field measurements in non-anechoic environments represent an interesting alternative to the utilization of the state-of-the-art equipment and facilities. Despite their proven usefulness, the mentioned systems are normally constructed around the expensive, laboratory-grade equipment, which contradicts the whole concept of low-cost measurements. This paper discusses a cost-efficient, mobile system for experimental validation of antennas. Its main components include the in-house developed rotary heads, an open-hardware-based vector network analyzer, and the measurements post-processing software. The cost of the system amounts to only around 3630 USD. The capabilities of the device have been demonstrated through measurements of two antenna structures. The considered performance figures include radiation pattern and single-direction gain vs. frequency. Comparisons against the measurements performed in benchmark conditions (anechoic chamber), as well as using professional network analyzer have also been provided. Furthermore, the documentation that facilitates the construction of the system components is shared in an online repository.

  • A mechanistically approached review upon assorted cell lines stimulated by athermal electromagnetic irradiation
    • Khadijeh Askaripour
    • Arkadiusz Żak
    2023 Full text CELL CYCLE

    The probable influence of electromagnetic irradiation on cancer treatment has been deduced from the interaction of artificial electromagnetic emissions with biological organisms. Nonetheless, the suspected health effects induced by electromagnetic-based technology imply that such a treatment may contaminate the adjacent healthy cells. Thus, gaining mechanistic insights into the problem is required to avoid athermal health hazards. To tackle that, the current review, based upon in vitro studies into assorted cell lines, depicts the alterations in physiological processes triggered by electromagnetic irradiation via addressing gene regulatory cascades. Furthermore, decisive factors in the hypothesized cause-effect linkage in terms of the cell line-associated, exposure-associated, or endpoint-associated parameters are highlighted. As a result, subcellular structures such as aberrant Ca2+ channels, rich glycocalyx charge, or high water content in cancerous cells, which have attracted a great deal of attention, can explain their higher susceptibility compared with healthy cells under irradiation. Affected by cell components or geometry, the cellular biological window correlates with the metabolic or cell cycle status and determines the irradiation that causes the maximum influence. For instance, correlations between the frequency (or intensity) of irradiation and cell excitability or between the duration of irradiation and cell doubling time are observed. There are unspecified signaling pathways such as the pathway of PPAR-γ or MAPKs, and also proteins devoid of any investigation such as p14, or S phase-related and G2 phase-related proteins. Other chains, such as the cAMP connection with mitochondrial ATP or ERK signaling, the association of Hsps releases with signaling pathways of MAPKs, or the role of different ion channels in regulating various cell processes, require further investigation.

  • A Monte Carlo Strategy to simulate Positrons and Positronium in biological Materials
    • Małgorzata Franz
    • Jan Franz
    2023 Full text Bio-Algorithms and Med-Systems

    We present an algorithm for Monte Carlo simulations of positron tracks in biological materials. The algorithm takes into account the cross-section data for elastic and inelastic collisions between positrons and molecules and processes like direct annihilation, ionization and positronium formation. In the case of positronium formation, the algorithm considers the interactions of positronium with molecules. The algorithm can be used to identify the processes that are responsible to determine the lifetime of the positrons and their annihilation mechanism (direct or through positronium formation).

  • A multi‑criteria approach to investigate spatial distribution,sources, and the potential toxicological effect of polycyclic aromatic hydrocarbons (PAHs) in sediments of urban retention tanks
    • Nicole Nawrot
    • Anna Pouch
    • Karolina Matej-Łukowicz
    • Ksenia Pazdro
    • Muhammad Mohsin
    • Shahabaldin Rezania
    • Ewa Wojciechowska
    2023 Full text ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

    Bottom sediments deposited in retention tanks (RTs) located on two urban streams (Oliwski and Strzyza) in the central part of Gdansk (Poland) were analysed for polycyclic aromatic hydrocarbons’ (PAHs) content. PAHs were extracted from samples with methylene chloride, then the extracts were subjected to clean-up applying the solid phase extraction (SPE) method. Quantitative and qualitative determination of 16 PAHs was performed with the use of gas chromatography/mass spectrometry technique. A multi-dimensional approach was applied to analyse PAHs’ spatial distribution, source, and contamination status. Potential sources of PAHs were verified using isomer ratios supported by a statistical approach. The Σ16PAHs (in mg/kg d.w.) ranged from 1.95 ± 0.64 to 20.4 ± 6.8 for RTs located on the Oliwski Stream and from 0.50 ± 0.17 to 8.6 ± 2.9 for RTs located on the Strzyza Stream. PAHs detected in bottom sediments were mainly composed of 4- and 5-ring compounds. PAH isomer ratios such as Phen/Anth, Flth/Pyr, B(a)A/B(a)A + Chry, Inpy/Inpy + B(ghi)P, Flth/Flth + Pyr, Anth/Anth + Phen, and Flth/Flth + Pyr suggested delivery pathways for biomass, coal, and petroleum combustion. Petrogenic PAHs related to fuel leaks from cars were not detected. Statistical analyses confirmed traffic and heating system sources, while factor analysis (FA) pointed out the abrasion of wasting parts of vehicles. Based on threshold levels presented in sediment quality guidelines (SQGs), in most cases, PAHs were at low levels with occasional negative biological effects on organisms. Only sediments deposited in two RTs located on the Oliwski Stream presented harmful features for sediment-dwelling organisms. The risk assessment performed accordingly to the Σ16PAHs presented a moderate and high risk for biota. This study not only reflects the direct threat related to PAH content in bottom sediments, but also highlights the overall pollution of an area, considered to be a recreational part of the city (Oliwski Stream catchment). The findings of this study highlight the need to launch preventative methods to protect the area against pollution from heating system emission and traffic.

  • A Multifunctional Microwave Filter/Sensor Component Using a Split Ring Resonator Loaded Transmission Line
    • Zahra Shaterian
    • Michał Mrozowski
    2023 Full text IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS

    This research is focused on the design and realiza2 tion of a microwave component with multifunctional filter/sensor 3 operation using a resonator-loaded transmission line (TL). It is 4 shown that while the structure acts as a bandstop filter, the 5 phase of the reflection coefficient from the loading resonator(s) 6 on a movable layer can be used for displacement sensing, thus 7 allowing for combining filtering with sensing in one device. 8 The proposed multifunctional mechanism is validated through 9 electromagnetic (EM) simulation of the structure. The concept 10 and the performance of the proposed device are further examined 11 through the fabrication and measurement of a multifunctional 12 filter/sensor component based on a microstrip TL loaded with 13 movable split ring resonators (SRRs).

  • A multi‐industry and cross‐country comparison of technology contribution to formal and informal knowledge sharing processes for innovativeness
    • Wioleta Kucharska
    • G. Scott Erickson
    2023 Full text Knowledge and Process Management

    The study explores the impact of organizational information technology (IT) competency on knowledge sharing, both explicit and tacit, in the context of innovativeness of products and processes. Knowledge sharing is then assessed in terms of tacit-to-explicit conversion and the impact of both types of knowledge on organizational innovation. Both process (internal) and product/service (external) innovation are included. As an extension, this IT competency to innovation framework is evaluated in context, both by nation (Poland and the United States) and by industry(IT, construction, and healthcare). The results obtained through the structural equation modeling method (sample size 2168 cases in total) exposed that IT competency dimensions matter for formal and informal knowledge-sharing processes and vary across countries and industries. For instance, in the US IT industry, IT-infrastructure,IT-knowledge, and IT-operations dimensions equally support explicit (formal) and tacit (informal) knowledge sharing. On the contrary, for the same industry in Poland, all dimensions support explicit knowledge sharing but regarding tacit knowledge sharing, only IT-knowledge supports it. Summing up the general findings, this study exposes that for tacit knowledge sharing, the critical IT-competency dimension is IT-knowledge, whereas for explicit- IT operations. Next, it clarifies that tacit knowledge sharing supports the explicit, and both are needed to introduce external innovations thanks to their significant impact on internal processes improvement.

  • A multithreaded CUDA and OpenMP based power‐aware programming framework for multi‐node GPU systems
    • Paweł Czarnul
    2023 Full text CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE

    In the paper, we have proposed a framework that allows programming a parallel application for a multi-node system, with one or more GPUs per node, using an OpenMP+extended CUDA API. OpenMP is used for launching threads responsible for management of particular GPUs and extended CUDA calls allow to manage CUDA objects, data and launch kernels. The framework hides inter-node MPI communication from the programmer who can benefit from the traditional OpenMP+CUDA API in a multi-node environment. For optimization, the implementation takes advantage of the MPI THREAD MULTIPLE mode allowing: multiple threads handling distinct GPUs as well as overlapping communication and computations transparently using multiple CUDA streams. The solution allows data parallelization across available GPUs in order to minimize execution time and supports a power-aware mode in which GPUs are automatically selected for computations using a greedy approach in order not to exceed an imposed power limit. We have implemented and benchmarked three parallel applications including: finding the largest divisors; verification of the Collatz conjecture; finding patterns in vectors. These were tested on three various systems: a GPU cluster with 16 nodes, each with NVIDIA GTX 1060 GPU; a powerful 2-node system – one node with 8x NVIDIA Quadro RTX 6000 GPUs, the second with 4x NVIDIA Quadro RTX 5000 GPUs; a heterogeneous environment with one node with 2x NVIDIA RTX 2080 and 2 nodes with NVIDIA GTX 1060 GPUs. We demonstrated effectiveness of the framework through execution times versus power caps within ranges of 100-1400W, 250-3000W and 125-600W for these systems respectively as well as gains from using two versus one CUDA streams per GPU. Finally, we have shown that for the testbed applications the solution allows to obtain high speed-ups between 89.3% to 97.4% of the theoretically assessed ideal ones, for 16 nodes and 2 CUDA streams, demonstrating very good parallel efficiency.

  • A new anisotropic bending model for nonlinear shells: Comparison with existing models and isogeometric finite element implementation
    • Eshwar J. Savitha
    • Roger Sauer
    2023 Full text INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES

    A new nonlinear hyperelastic bending model for shells formulated directly in surface form is presented, and compared to four existing prominent bending models. Through an essential set of elementary nonlinear bending test cases, the membrane and bending stresses of each model are examined analytically. Only the proposed bending model passes all the test cases, while the other bending models either fail or only pass the test cases for small deformations. The proposed new bending model can handle large deformations and initially curved surfaces. It is based on the principal curvatures and their directions in the initial configuration, and it thus can have different bending moduli along those directions. These characteristics make it flexible in modeling a given material, while it does not suffer from the pathologies of existing bending models. Further, the bending models are compared computationally through four classical benchmark examples and one contact example. As the underlying shell theory is based on Kirchhoff–Love kinematics, isogeometric NURBS shape functions are used to discretize the shell surface. The linearization and efficient finite element implementation of the proposed new model are also provided.

  • A New Approach to Capacitive Sensor Measurements Based on a Microcontroller and a Three-Gate Stable RC Oscillator
    • Zbigniew Czaja
    2023 Full text IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

    A complete smart capacitive sensor solution basedA complete smart capacitive sensor solution based on a microcontroller was developed. This approach includes the development of both the hardware and software. The hardware part comprises an 8-bit microcontroller equipped with two timers/counters and a three-gate stable RC relaxation oscillator. The software part handles system configuration, measurement control, communication control, and data processing. Hence, the microcontroller acts as a frequency meter with an adaptive measuring time, and the relaxation oscillator generates a square wave with a frequency depending on the value of the capacitance of the sensor. The paper also proposes a calibration method that reduces the measurement range to 1 pF. The experimentally proven relative measurement errors of sensor capacitance are less than 0.012% for values smaller than 12 pF, and less than 0.0084% for values from 12 pF to 300 pF.

  • A new approach to cross-bonding in medium voltage cable lines
    • Jacek Klucznik
    2023 Full text Przegląd Elektrotechniczny

    The medium voltage underground cable sheaths are usually bonded and earthed in every substation on the cable route. This results in additional power losses in the sheaths. The paper presents an idea of reducing power losses caused by sheaths cross-bonding. The idea of sheaths cross-connecting only in selected MV/LV substations is given instead of a typical solution, where sheaths cross-bonding requires installing additional joints on the cable route. It leads to a significant power losses reduction while investment cost remains low. Two cases are analysed in the paper: a theoretical simple radial network and a part of a real open-loop network. A significant power losses reduction was obtained in both cases.

  • A new approach to designing control of dissolved oxygen and aeration system in sequencing batch reactor by applied backstepping control algorithm
    • Michał Kolankowski
    • Michał Banach
    • Robert Piotrowski
    • Tomasz Ujazdowski
    2023 Full text Acta Mechanica et Automatica

    The Wastewater Treatment Plant (WWTP) is a very complex system, due to its nonlinearity, time-variance, and multiple time scales in its dynamics among others. The most important control parameter in a WWTP is the Dissolved Oxygen (DO) concentration. The tracking problem of the DO concentration is one of the most fundamental issues in biological wastewater treatment. Proper DO concentration control is necessary to achieve adequate biological conditions for microorganisms in a WWTP. Aeration is an im-portant, but expensive activity. It is performed using an aeration system, which includes blowers, pipelines and diffusers. This pa-per presents a new approach to designing a nonlinear control system for DO concentration control using an adaptive backstepping algorithm. A model of biological processes and a model of aeration system are applied for control system design. Simulation tests of the control system are performed. Very good control results were obtained. The proposed solution has proved to be effective and computationally efficient.

  • A new approach to β-decays studies impacting nuclear physics and astrophysics: The PANDORA setup
    • David Mascali
    • Debora Santonocito
    • Maurizio Maria Busso
    • Luigi Celona
    • Alessio Galatà
    • M. La Cognata
    • Giorgio Sebastiano Mauro
    • A. Mengoni
    • Eugenia Naselli
    • F. Odorici
    • S. Palmerini
    • Angelo Pidatella
    • R. Ràcz
    • Simone Taioli
    • Giuseppe Torrisi
    2023 Full text EPJ Web of Conferences

    Theory predicts that lifetimes of β-radionuclides can change dramatically as a function of their ionization state. Experiments performed in Storage Rings on highly ionized atom have proven nuclei can change their beta decay lifetime up to several orders of magnitude. The PANDORA (Plasmas for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry) experiment is now conceived to measure, for the first time, nuclear β-decay rates using magnetized laboratory plasma that can mimic selected stellar-like conditions in terms of the temperature of the environment. The main feature of the setup which is based on a plasma trap to create and sustain the plasma, a detector array for the measurement of the gamma-rays emitted by the daughter nuclei after the decay process and the diagnostic tools developed to online monitor the plasma will be presented. A short list of the physics cases we plan to investigate together with an evaluation of their feasibility will be also discussed.

  • A new deterministic PSO algorithm for real-time systems implemented on low-power devices
    • Zofia Długosz
    • Michał Rajewski
    • Rafał Długosz
    • Tomasz Talaśka
    • Witold Pedrycz
    2023 JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS

    The paper presents a novel, deterministic particle swarm optimization (PSO) algorithm, facilitating its implementation in low-power application specific integrated circuits (ASIC) realized in CMOS technology. The PSO algorithms are commonly used in a variety of optimization problems. They allow to search for a global extreme in a selected fitness function, which is used for numerical modeling of specific optimized problems. The conventional version of the algorithm is relatively difficult to implement directly in hardware, especially when each particle is represented by a separate circuit working in parallel with other particles. In such a situation, each particle has to be equipped with its own copy of each function. One of the problems is, for example, an efficient realization of the random function block that provides for each particle some factors used in computing a cognitive and a social velocity components. In this paper we shows a novel way to work around this problem. In the proposed approach the random function does not need to be used. It has been replaced by a simple computationally deterministic mechanism, which at the level of the overall swarm allows for effective emulation of the former random mechanism. We proposed such simplifications that reduce the formulas describing the algorithm to only basic arithmetic and logic operations. Comprehensive investigations have shown that performance of the proposed approach is comparable with its original version or in may situations even better. The proposed algorithm was tested with numerous test functions (50 runs for each tested function), to verify its flexibility and adaptation abilities to different problems.

  • A new finite element with variable Young's modulus
    • Katarzyna Mazur
    • Marek Krawczuk
    • Leszek Dąbrowski
    2023 International Journal for Numerical Methods in Biomedical Engineering

    The Finite Element Method (FEM) is a numerical technique that is well-established in the field of engineering. However, in biological sciences, it is justtaking its first steps. Bone tissue is an example of biological material which isexposed to high loads in its natural environment. Practically every movementof the body results in changing stress levels in the bone. Nature copes with thisvery well but when human intervention is necessary (e.g., endoprosthesesimplants) bone strength has to be determined based on experience since bonetissue has a very heterogeneous structure. The goal of this paper is to demon-strate how standard FEM calculations may be readily modified to provide forvariable material properties of such materials as, for example, bone or wood.

  • A new index for statistical analyses and prediction of travelling ionospheric disturbances
    • Claudia Borries
    • Arthur Amaral Ferreira
    • Grzegorz Nykiel
    • Renato Alves Borges
    2023 Full text JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS

    Travelling Ionospheric Disturbances (TIDs) are signatures of atmospheric gravity waves (AGWs) observed in changes in the electron density. The analysis of TIDs is relevant for studying coupling processes in the thermosphere–ionosphere system. A new TID index is introduced, which is based on an easy extension of the commonly used approach for TID detection. This TID activity index, which can be applied for individual Global Navigation Satellite Systems (GNSS) stations and also for mapping TID activity, is capable to study both Large Scale TIDs (LSTIDs) and Medium Scale TIDs (MSTIDs). is well applicable for statistical analyses and investigations of the source mechanisms of TIDs. Correlation studies presented here reveal that LSTID magnitudes at mid-latitudes are well correlated with solar wind derived parameters, like the Kan-Lee merging electric field (), the intermediate function ( ) and the modified version of the Akasufo parameter (3). Thus, the magnitude of the global solar-wind energy input into the Earth’s magnetosphere–ionosphere–thermosphere system is most relevant for the LSTID generation. The correlation with common geomagnetic activity indices shows that also sudden changes in the magnetosphere–ionosphere–thermosphere system are relevant. Good correlation results are limited to midlatitudes. High-latitude regions are impacted by auroral processes and low-latitude regions by coupling from below and other instabilities. can be used for the modelling and prediction as demonstrated with a prediction model for storm induced LSTIDs, based on solar wind observations only. Very good performance of this LSTIDs prediction model in mid-latitudes has been proven.

  • A New, Reconfigurable Circuit Offering Functionality of AND and OR Logic Gates for Use in Algorithms Implemented in Hardware
    • Tomasz Talaśka
    • Rafał Długosz
    • Tatjana Nikolić
    • Goran Nikolić
    • Tomasz Stefański
    • Michał Długosz
    • Michał Talaśka
    2023

    The paper presents a programmable (using a 1-bit signal) digital gate that can operate in one of two OR or AND modes. A circuit of this type can also be implemented using conventional logic gates. However, in the case of the proposed circuit, compared to conventional solutions, the advantage is a much smaller number of transistors necessary for its implementation. Circuit is also much faster than its conventional counterpart. The logic gate was implemented in the 180nm CMOS technology and verified using Hspice simulations. There are many possible applications for this gate, mostly in artificial intelligence and pattern recognition algorithms implemented at the transistor level.

  • A Note on Fractional Curl Operator
    • Tomasz Stefański
    • Marek Czachor
    2023 IEEE Antennas and Wireless Propagation Letters

    In this letter, we demonstrate that the fractional curl operator, widely used in electromagnetics since 1998, is essentially a rotation operation of components of the complex Riemann–Silberstein vector representing the electromagnetic field. It occurs that after the wave decomposition into circular polarisations, the standard duality rotation with the angle depending on the fractional order is applied to the left-handed basis vector whilst the right-handed basis vector stems from the complex conjugation of the left-handed counterpart. Therefore, the fractional curl operator describes another representation of rotations of the electromagnetic field decomposed into circular polarisations. Finally, we demonstrate that this operator can describe a single-qubit phase-shift gate in quantum computing.

  • A note on simple bifurcation of equilibrium forms of an elastic rod on a deformable foundation
    • Marek Izydorek
    • Joanna Janczewska
    2023 TOPOLOGY AND ITS APPLICATIONS

    We study bifurcation of equilibrium states of an elastic rod on a two-parameter Winkler foundation. In the article "Bifurcation of equilibrium forms of an elastic rod on a two-parameter Winkler foundation" [Nonlinear Anal., Real World Appl. 39 (2018) 451-463] the existence of simple bifurcation points was proved by the use of the Crandall-Rabinowitz theorem. In this paper we want to present an alternative proof of this fact based on the Krasnosielski theorem.

  • A novel approach in wood waste utilization for manufacturing of catalyst-free polyurethane-wood composites (PU-WC)
    • Adam Olszewski
    • Paulina Kosmela
    • Łukasz Piszczyk
    2023 Full text Sustainable Materials and Technologies

    In recent decades, due to the increase in environmental awareness and noticeable environmental degradation, the area of wood waste management has attracted increasing attention. The purpose of this study is to develop a new type of highly filled polyurethane wood-composite (PU-WC) by the utilization of large amount of wood wastes without addition of a catalyst. Although wood-plastic composites (WPCs) are widely known, there is still a lack of knowledge about WPCs with a polyurethane matrix. Obtained results showed that composites with a wood content of up to 80% show mechanical properties to commonly used MDF boards. This may be caused proper adhesion between polyurethane matrix and the wooden filler which was confirmed by scanning electron microscopy. The flexural strength of the manufactured composites varied between 19.25 and 25.11 MPa, while the flexural modulus varied between 966 and 1255 MPa. Dynamic mechanical analysis (DMA) of the composites showed a shift of Tgβ (from −70.3 to −52.3 °C) and Tgα (from 94.9 to 117.8 °C) to higher temperatures with increasing filler amount. The observed shift could be interpreted as a reduction of polymer chain mobility and an increase in cross-linking density of composites with a higher amount of wood. This is caused by chemical reactions between isocyanates and reactive hydroxyl groups on the wood surface. Thermogravimetric analysis has shown that PU-WC degrades in one step with Tmax at around 360 °C and T2% significantly reduce with greater addition of wood. Water absorption tests that water absorption strongly depends on wood content and varies between 13 and 80%. Moreover, cyclic water absorption tests showed no considerable difference between the water adsorption of samples after each cycle. Our work suggests that PU-WC can be used successfully as a potential substitute for wood or different types of wood-plastic composites (WPC).

  • A Novel Approach to Fully Nonlinear Mathematical Modeling of ‎Tectonic Plates
    • Shahriar Dastjerdi
    • Mohammad Malikan
    • Bekir Akgöz
    • Ömer Civalek
    • Victor Eremeev
    2023 Full text Journal of Applied and Computational Mechanics

    The motion of the Earth's layers due to internal pressures is simulated in this research with an efficient mathematical model. The Earth, which revolves around its axis of rotation and is under internal pressure, will change the shape and displacement of the internal layers and tectonic plates. Applied mathematical models are based on a new approach to shell theory involving both two and three-dimensional approaches. It is the first time studying all necessary measures that increase the accuracy of the obtained results. These parameters are essential to perform a completely nonlinear analysis and consider the effects of the Earth’s rotation around its axis. Unlike most modeling of nonlinear partial differential equations in applied mechanics that only considers nonlinear effects in a particular direction, the general nonlinear terms are considered in the present study, which increases the accuracy of the amount of displacement of the Earth's inner layers. Also, the fully nonlinear and dynamic differential equations are solved by a semi-analytical polynomial method which is an innovative and efficient method. Determining the amount of critical pressure at the fault location that will cause phenomena such as earthquakes is one of the useful results that can be obtained from the mathematical modeling in this research.

  • A novel concept of enhanced direct-contact condensation of vapour- inert gas mixture in a spray ejector condenser
    • Dariusz Mikielewicz
    • Milad Amiri
    • Michał Klugmann
    • Jaroslaw Mikielewicz
    2023 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER

    An analytical model of direct steam condensation (DCC) in the novel idea of spray ejector condenser (SEC) in the presence of inert gas has been developed. It is based on continuity, momentum and energy equations for the steam-carbon dioxide mixture and direct contact condensation mechanisms due to heat transfer and concentration. Crucial in the process of DCC is atomisation of the motive fluid in the ejector. The effect of atomised droplet size is exhibiting a significant amplification influence with increasing size of the droplet. Motive fluid is driving the secondary fluid-mixture of steam and inert gas in the Venturi nozzle and is cold enough to cause direct condensation. The intensity of heat transfer process from steam to water when the phases are in direct contact is much higher than the heat transfer intensity in surface heat exchangers. The analytical model pertains to a subcritical flow of a mixture of steam and gas in SEC. The model exhibits satisfactory agreement with experimental data. The model of DCC predicts higher values of temperature drop between inlet and outlet from the mixing section for the case of smaller steam-CO2 flow rates. Increasing the flow rate of steam mixture from 1.2 g/s to 3.6 g/s results in a reduction of steam mixture temperature from 25 ◦C to 14 ◦C respectively, at CO2 flow rate of 6.8 m3 /h. Condensation without presence of CO2 in the same range of steam flow rate, i.e. from 1.2 g/s to 3.6 g/s results in reduction of steam mixture temperature from 56 ◦C to 25 ◦C respectively, confirming in such way the effect of CO2 presence on the efficiency of DCC. Such model allow for discussion of parameters affecting process of condensation in SEC and ability of application such condenser in power plants.

  • A novel DEM-based pore-scale thermal-hydro-mechanical model for fractured non-saturated porous materials
    • Marek Krzaczek
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    2023 Full text Acta Geotechnica

    Do propagacji pęknięć wykorzystano nowy oparty na DEM, termiczno-hydromechaniczny model dwufazowego przepływu płynu w skali porów rozszerzony o wymianę ciepła w nienasyconych materiałach porowatych o małej porowatości. Wykonano obliczenia numeryczne dla kohezyjnych próbek ziarnistych przy użyciu DEM w pełni sprzężonego z CFD (opartego na sieci przepływu płynu) i wymianą ciepła, który zintegrował mechanikę dyskretną z mechaniką płynów i wymianą ciepła w mezoskali. Zarówno płyn (dyfuzja i adwekcja) i kohezyjne cząstki (przewodnictwo) brały udział w przenoszeniu ciepła. Wyniki stosując sprzężony model termo-hydro-mechaniczny (THM) zostały najpierw porównane z rozwiązaniem analitycznym klasycznego jednowymiarowego transportu ciepła. Wyniki liczbowe i analityczne były w pełni zgodne. Wpływ adwekcji na ochłodzenie na zespół kohezyjnych cząstek został następnie zademonstrowany numerycznie dla niskich i wysokich liczb Pecleta. Wreszcie użyteczność modelu THM została udowodniona w teście skurczu termicznego, w którym zastosowano próbkę złożoną z kohezyjnych cząstek był poddany chłodzeniu, w wyniku czego powstało makropęknięcie. Zbadano wpływ makropęknięcia na rozkład ciśnienia płynu, gęstości, prędkości i temperatury.

  • A novel hardware implemented programmable controller adapted to cooperate with AI tuning algorithms in real time systems
    • Tomasz Talaśka
    • Zofia Długosz
    • Rafał Długosz
    2023 JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS

    A novel, transistor level PID (proportional–integrating–derivative) controller is proposed that may be easily coupled with various AI algorithms responsible for adjusting its main factors. In our work we focus on a discrete-time digital approach, as it facilities realization a flexible and programmable structure that can be quickly re-configured depending on varying environment conditions. One of the novelties of the proposed solution is its parallel and asynchronous structure that requires only simple 2-phases clock. Each of the P, I and D blocks is realized as a separate channel with its own multi-bit multiplier, a summing circuit and a short delay line (in case of I and D blocks). The circuit features small chip area. For the input signals, and the coefficients of the controller being encoded as 8-bit signals the number of transistors does not exceed 13,000, which translates into the chip area not exceeding 0.1 mm in the CMOS 130 nm technology. Data rate of the controller can achieve 200–330 MSamples/s, with power dissipation not exceeding 1 mW. The proposed solution is suitable for miniaturized microsystems, for example high performance MEMS devices, in which small sizes and high data rate become very important features.