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Gdańsk University of Technology

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Publications from the year 2023

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  • 16-kanałowy moduł LED do systemu wspomagającego rozwój roślin sterowany za pomocą Raspberry PI
    • Mateusz Feldzenstajn
    • Jerzy Pluciński
    • Sebastian Siedlecki
    • Adam Mazikowski
    2023 Full text Przegląd Elektrotechniczny

    Opracowywane są nowe rozkłady widma światła, które wpływają na poprawę zarówno ilości plonów i jakości dokonywanych zbiorów. W celu uproszczenia wprowadzania zmian widma w procesach badawczych oraz w celu przyspieszenia i zrównoleglenia badań w tym zakresie został opracowany niedrogi programowalny moduł LED pozwalający sterować 16 niezależnymi stałoprądowymi kanałami. Niska cena proponowanego rozwiązania oraz jeden sterownik obsługujący do 12 modułów LED może przyczynić się do bardziej efektywnych poszukiwań optymalnego widma dla poszczególnych gatunków roślin.

  • 2-Methoxyestradiol and Hydrogen Peroxide as Promising Biomarkers in Parkinson’s Disease
    • Paulina Bastian
    • Lucyna Konieczna
    • Jarosław Dulski
    • Agnieszka Daca
    • Dagmara Jacewicz
    • Agata Płoska
    • Narcyz Knap
    • Jarosław Sławek
    • Tomasz Baczek
    • Leszek Kalinowski
    • Joanna Drzeżdżon
    • Anna Roszmann
    • Mariusz Belka
    • Magdalena Górska-Ponikowska
    2023 Full text MOLECULAR NEUROBIOLOGY

    Estrogens function in numerous physiological processes including controlling brain cell growth and differentiation. 2-Meth- oxestradiol (2-ME2), a 17β-estradiol (E2) metabolite, is known for its anticancer effects as observed both in vivo and in vitro. 2-ME2 affects all actively dividing cells, including neurons. The study aimed to determine whether 2-ME2 is a potentially cancer-protective or rather neurodegenerative agent in a specific tissue culture model as well as a clinical setup. In this study, 2-ME2 activity was determined in a Parkinson’s disease (PD) in vitro model based on the neuroblastoma SH-SY5Y cell line. The obtained results suggest that 2-ME2 generates nitro-oxidative stress and controls heat shock proteins (HSP), resulting in DNA strand breakage and apoptosis. On the one hand, it may affect intensely dividing cells preventing cancer develop- ment; however, on the other hand, this kind of activity within the central nervous system may promote neurodegenerative diseases like PD. Thus, the translational value of 2-ME2’s neurotoxic activity in a PD in vitro model was also investigated. LC–MS/MS technique was used to evaluate estrogens and their derivatives, namely, hydroxy and methoxyestrogens, in PD patients’ blood, whereas the stopped-flow method was used to assess hydrogen peroxide (H2O2) levels. Methoxyestrogens and H2O2 levels were increased in patients’ blood as compared to control subjects, but hydoxyestrogens were simultaneously decreased. From the above, we suggest that the determination of plasma levels of methoxyestrogens and H2O2 may be a novel PD biomarker. The presented research is the subject of the pending patent application “The use of hydrogen peroxide and 17β-estradiol and its metabolites as biomarkers in the diagnosis of neurodegenerative diseases,” no. P.441360.

  • 3D Metamaterial Ultra-Wideband Absorber for curved surface
    • Mahdi Norouzi
    • Saughar Jarchi
    • Mohsen Miab
    • Meisam Esfandiari
    • Ali Lalbakhsh
    • Sławomir Kozieł
    • Sam Reisenfeld
    • Gholamhosein Moloudian
    2023 Full text Scientific Reports

    This paper proposes a three-dimensional metamaterial absorber based on a resistive film patch array to develop a low-cost, lightweight absorber for curved surfaces. An excellent absorption over a large frequency band is achieved through two different yet controllable mechanisms; In the first mechanism, a considerable attenuation in the wave power is achieved via graphite resistive films. The absorption is then intensified through magnetic dipoles created by the surface currents, leading to absorption peaks. The simulation results of the absorber show that a broadband absorption greater than 85% is achieved over 35 to 400 GHz for both TE and TM polarization waves at normal incidence. The structure has more than 167% and 80% absorption bandwidth above 85% and 90%, respectively. It is shown that the proposed metamaterial absorber is independent of incident wave polarization. In addition, the structure is insensitive to incident angle up to 60˚ for TE mode and full range angle 90˚for TM mode. To describe the physical mechanism of the absorber, E-field, power loss density and surface current distributions on the structure are calculated and shown. Moreover, the oblique incidence absorption efficiency is also explained. This absorber paves the way for practical applications, such as sensing, imaging and stealth technology. In addition, the proposed structure can be extended to terahertz, infrared and optical regions.

  • 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 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.