2023 - Publications Repository - Gdańsk University of Technology

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Publications from the year 2023

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Reducing the Uncertainty of the Moving Object Location Measurement with the Method of Quasi-Multiple Measurement in GNSS Technology in Symmetrical Arrangement
- Jacek Skibicki
- Andrzej Wilk
- Władysław Koc
- Roksana Licow
- Jacek Szmagliński
- Piotr Chrostowski
- Sławomir Judek
- Krzysztof Karwowski
- Sławomir Grulkowski
2023 Full text SENSORS
The article presents a solution to the problem of limited accuracy of dynamic measurements performed with GNSS receivers. The proposed measurement method is a response to the needs related to the assessment of the measurement uncertainty of the position of the track axis of the rail transport line. However, the problem of reducing the measurement uncertainty is universal for many different situations where high accuracy of positioning of objects is required, especially in motion. The article proposes a new method to determine object’s location using geometric constraints of a number of GNSS receivers arranged in symmetric configuration. The proposed method has been verified by comparing signals recorded by up to five GNSS receivers during stationary and dynamic measurements. The dynamic measurement was made on a tram track within the framework of a cycle of studies upon effective and efficient methods to catalogue and diagnose tracks. A detailed analysis of the results obtained with the quasi-multiple measurement method confirms remarkable reduction in their uncertainty. Their synthesis shows the usability of this method in dynamic conditions. The proposed method is expected to find application in measurements requiring high accuracy, and in case of deterioration of the signal quality from satellites by one or more of GNSS receivers due to the appearance of natural obstacles.
Reduction in Errors in Roughness Evaluation with an Accurate Definition of the S-L Surface
- Przemysław Podulka
- Wojciech Macek
- Ricardo Branco
- Reza Masoudi Nejad
2023 Full text Materials
Characterization of surface topography, roughly divided into measurement and data analysis, can be valuable in the process of validation of the tribological performance of machined parts. Surface topography, especially the roughness, can respond straightly to the machining process and, in some cases, is defined as a fingerprint of the manufacturing. When considering the high precision of surface topography studies, the definition of both S-surface and L-surface can drive many errors that influence the analysis of the accuracy of the manufacturing process. Even if precise measuring equipment (device and method) is provided but received data are processed erroneously, the precision is still lost. From that matter, the precise definition of the S-L surface can be valuable in the roughness evaluation allowing a reduction in the rejection of properly made parts. In this paper, it was proposed how to select an appropriate procedure for the removal of the L- and S- components from the raw measured data. Various types of surface topographies were considered, e.g., plateau-honed (some with burnished oil pockets), turned, milled, ground, laser-textured, ceramic, composite, and, generally, isotropic. They were measured with different (stylus and optical) methods, respectively, and parameters from the ISO 25178 standard were also taken into consideration. It was found that commonly used and available commercial software methods can be valuable and especially helpful in the precise definition of the S-L surface; respectively, its usage requires an appropriate response (knowledge) from the users.
Reduction of CO2 Emissions from Offshore Combined Cycle Diesel Engine-Steam Turbine Power Plant Powered by Alternative Fuels
- Wojciech Olszewski
- Marek Dzida
- Van Giao Nguyen
- Dao Nam Cao
2023 Full text Polish Maritime Research
Diverse forms of environmental pollution arise with the introduction of materials or energy that exert adverse effects on human health, climate patterns, ecosystems, and beyond. Rigorous emission regulations for gases resulting from fuel combustion are being enforced by the European Union and the International Maritime Organization (IMO), directed at maritime sectors to mitigate emissions of SOx, NOx, and CO2. The IMO envisions the realisation of its 2050 targets through a suite of strategies encompassing deliberate reductions in vessel speed, enhanced ship operations, improved propulsion systems, and a transition towards low and zero-emission fuels such as LNG, methanol, hydrogen, and ammonia. While the majority of vessels currently depend on heavy fuel or low-sulphur fuel oil, novel designs integrating alternative fuels are gaining prominence. Technologies like exhaust gas purification systems, LNG, and methanol are being embraced to achieve minimised emissions. This study introduces the concept of a high-power combined ship system, composed of a primary main engine, a diesel engine, and a steam turbine system, harnessing the energy contained within the flue gases of the main combustion engine. Assumptions, constraints for calculations, and a thermodynamic evaluation of the combined cycle are outlined. Additionally, the study scrutinises the utilisation of alternative fuels for ship propulsion and their potential to curtail exhaust emissions, with a specific focus on reducing CO2 output
Reduction of exceeding the guaranteed service time for external trucks at the DCT Gdańsk container terminal using a six sigma framework
- Karol Moszyk
- Mariusz Deja
2023 Full text International Journal of Lean Six Sigma
Purpose The purpose of this research was to investigate ways to reduce the average amount of exceeded guaranteed service time for external trucks at Deepwater Container Terminal Gdańsk Sp z o.o. (DCT Gdańsk) via dosing the gate activities, in particular IN-Gate entry process of trucks carrying import/export/transit containers. Design/methodology/approach A Six Sigma methodology with the DMAIC methods along with the SIPOC chart, cause and effect diagram, scatterplot, benchmark and brainstorming and finally multi-voting tool are used as analyses tools in this research. Findings Deepwater Container Terminal Gdańsk Sp z o.o. (DCT Gdańsk) reorganized and modernized the Gate Operations. Gate reorganization and modernization includes streaming line traffic at the gates, external parking lot optimization, implementation of dedicated supporting software and installation of dedicated CCTV cameras to provide 24h life view. During gates development, the external truck service times data were collected and analysed. The obtained materials concerned the measurement of the average truck turnaround time before and after the implementation of the improvements. Originality/value The proposed approach of reducing the average amount of exceeded guaranteed service time of external trucks at the container terminal is unique and relatively cheap mainly due to organisational changes with some widely available low-cost investments and can be applied on a different scale to other container terminals or to transport and logistics companies.
Reemission of inorganic pollution from permafrost? A freshwater hydrochemistry study in the lower Kolyma basin (North-East Siberia)
- Danuta Szumińska
- Kozioł Krystyna
- Sergey R. Chalov
- Vasilii A. Efimov
- Marcin Frankowski
- Sara Lehmann-konera
- Żaneta Polkowska
2023 LAND DEGRADATION & DEVELOPMENT
Permafrost regions are under particular pressure from climate change resulting in widespread landscape changes, which impact also freshwater chemistry. We investi- gated a snapshot of hydrochemistry in various freshwater environments in the lower Kolyma river basin (North-East Siberia, continuous permafrost zone) to explore the mobility of metals, metalloids and non-metals resulting from permafrost thaw. Partic- ular attention was focused on heavy metals as contaminants potentially released from the secondary source in the permafrozen Yedoma complex. Permafrost creeks represented the Mg-Ca-Na-HCO3-Cl-SO 4 ionic water type (with mineralisation in the range 600–800 mg L1 ), while permafrost ice and thermokarst lake waters were the HCO 3-Ca-Mg type. Multiple heavy metals (As, Cu, Co, Mn and Ni) showed much higher dissolved phase concentrations in permafrost creeks and ice than in Kolyma and its tributaries, and only in the permafrost samples and one Kolyma tributary we have detected dissolved Ti. In thermokarst lakes, several metal and metalloid dis- solved concentrations increased with water depth (Fe, Mn, Ni and Zn – in both lakes; Al, Cu, K, Sb, Sr and Pb in either lake), reaching 1370 μg L1 Cu, 4610 μg L1 Mn, and 687 μg L1 Zn in the bottom water layers. Permafrost-related waters were also enriched in dissolved phosphorus (up to 512 μg L1 in Yedoma-fed creeks). The impact of permafrost thaw on river and lake water chemistry is a complex problem which needs to be considered both in the context of legacy permafrost shrinkage and the interference of the deepening active layer with newly deposited anthropogenic contaminants.
Reinforcing and plasticizing effects of reclaimed rubber on the vulcanization and properties of natural rubber
- Teng Ren
- Pan Song
- Weihong Yang
- Krzysztof Formela
- Shifeng Wang
2023 JOURNAL OF APPLIED POLYMER SCIENCE
The production of high-added value reclaimed rubber (RR) is of great signifi-cance for the sustainability of rubber industries. To green recycle waste rub-bers and broaden the application of RR, a RR material with potentialreinforcing and plasticizing effects on nature rubber (NR) composites are pre-pared by a thermo-oxidative reclamation process. The reclamation degree ofRR is controlled by adjusting the content of soybean oil. The plasticizing effectis demonstrated by the decrease of torque during vulcanization and theenhancement of elongation at break of NR/RR composites with the increasingreclamation of RR. The tensile strength of NR/RR composites is enhanced byadding the RR, and the existence of RR also improves the thermal stability andrheological properties of NR/RR composites. The formation of new bound rub-ber in NR/RR compound indicates the reinforcing ability of RR. In addition,the average particle size of RR reaches nano-scale according to scanning elec-tron microscope photographs and its dispersion in NR/RR compounds isimproved with the increasing reclamation degree of RR as shown in Payneeffect. This work demonstrates the reinforcing and plasticizing ability of theRR, which is beneficial to improving the added value of reclaimed and broad-ening its application.
Rekordowe liczby pierwsze
- Marek Kubale
2023 Pismo PG
Problem liczb pierwszych ma długą historię sięgającą czasów starożytnych. W śród liczb całkowitych liczby pierwsze grają rolę analogiczną do pierwiastków w chemii.
Relationship between Chemical Structure and Biological Activity Evaluated In Vitro for Six Anthocyanidins Most Commonly Occurring in Edible Plants
- Izabela Koss-Mikołajczyk
- Agnieszka Bartoszek-Pączkowska
2023 Full text MOLECULES
Numerous studies have provided evidence that diets rich in anthocyanins show a broad spectrum of health benefits. Anthocyanins in nature are usually found in the form of glycosides. Their aglycone forms are called anthocyanidins. The chemical structure of anthocyanins is based on the flavylium cation, but they differ in the position and number of substituents. However, the bioactives and foods that contain them are frequently treated as a uniform group of compounds exhibiting the same biological activity, without paying attention to the structural differences between individual anthocyanidins. The aim of this study was to find out how structural differences impact the biological activity of the six most common dietary anthocyanidins, i.e., delphinidin (Dp), petunidin (Pt), cyanidin (Cd), malvidin (Mv), pelargonidin (Pg) and peonidin (Po). The study concentrated on redox-related phenomena and compared the following parameters: antioxidant activity (measured using various methods: spectrophotometric tests (ABTS, DPPH), ORAC assay and CAA test (cellular antioxidant activity)), the ability to inhibit growth of human colon cancer cells (HT29; determined using MTT assay), and the ability of studied compounds to protect DNA from oxidative damage (comet assay). Based on the obtained results, the relationship between the structure of studied antho- cyanidins and their biological activity was assessed. The obtained results revealed that the number and position of the hydroxyl and methoxy groups in the anthocyanidin structure strongly influenced not only the color of anthocyanidins but most of all their antioxidant and biological activities.
Release of Encapsulated Bioactive Compounds from Active Packaging/Coating Materials and Its Modeling: A Systematic Review
- Shahida Anusha Siddiqui
- Shubhra Singh
- Nur Alim Bahmid
- Taha Mehany
- Douglas J. H. Shyu
- Elham Assadpour
- Narjes Malekjani
- Roberto Castro Munoz
- Seid Mahdi Jafari
2023 Full text Colloids and Interfaces
The issue of achieving controlled or targeted release of bioactive compounds with specific functional properties is a complex task that requires addressing several factors, including the type of bioactive, the nature of the delivery system, and the environmental conditions during transportation and storage. This paper deals with extensive reporting for the identification of original articles using Scopus and Google Scholar based on active packaging as a novel packaging technology that controls the release of antimicrobial agents encapsulated into carriers in the food packaging systems. For evidence-based search, the studies were extracted from 2015 to 2020 and screened using the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Following the review and screening of publications, 32 peer-reviewed articles were subjected to systematic analysis. The preliminary search indicated that the encapsulation of bioactives enhances their bioavailability and stability. From a theoretical viewpoint, mathematical models play an important role in understanding and predicting the release behavior of bioactives during transportation and storage, thus facilitating the development of new packaging material by a systematic approach. However, only a few studies could formulate parameters for mathematical models in order to achieve the specific release mechanism regulated for the quality and safety of foods. Therefore, this paper will cover all encapsulation approaches, active packaging, and mathematical modeling in the food industry into structural form and analyze the challenges faced by the complex nature of active packaging in real food systems.
Release systems based on self-assembling RADA16-I hydrogels with a signal sequence which improves wound healing processes
- Maria Dzierżyńska
- Justyna Sawicka
- Milena Deptula
- Paweł Sosnowski
- Piotr Sass
- Barbara Peplińska
- Zuzanna Pietralik-Molińska
- Martyna Fularczyk
- Franciszek Kasprzykowski
- Jacek Zieliński
- Maciej Kozak
- Paweł Sachadyn
- Michal Pikula
- Sylwia Rodziewicz-Motowidło
2023 Full text Scientific Reports
Self-assembling peptides can be used for the regeneration of severely damaged skin. They can act as scaffolds for skin cells and as a reservoir of active compounds, to accelerate scarless wound healing. To overcome repeated administration of peptides which accelerate healing, we report development of three new peptide biomaterials based on the RADA16-I hydrogel functionalized with a sequence (AAPV) cleaved by human neutrophil elastase and short biologically active peptide motifs, namely GHK, KGHK and RDKVYR. The peptide hybrids were investigated for their structural aspects using circular dichroism, thiofavin T assay, transmission electron microscopy, and atomic force microscopy, as well as their rheological properties and stability in diferent fuids such as water or plasma, and their susceptibility to digestion by enzymes present in the wound environment. In addition, the morphology of the RADA-peptide hydrogels was examined with a unique technique called scanning electron cryomicroscopy. These experiments enabled us to verify if the designed peptides increased the bioactivity of the gel without disturbing its gelling processes. We demonstrate that the physicochemical properties of the designed hybrids were similar to those of the original RADA16-I. The materials behaved as expected, leaving the active motif free when treated with elastase. XTT and LDH tests on fibroblasts and keratinocytes were performed to assess the cytotoxicity of the RADA16-I hybrids, while the viability of cells treated with RADA16-I hybrids was evaluated in a model of human dermal fibroblasts. The hybrid peptides revealed no cytotoxicity; the cells grew and proliferated better than after treatment with RADA16-I alone. Improved wound healing following topical delivery of RADA-GHK and RADA-KGHK was demonstrated using a model of dorsal skin injury in mice and histological analyses. The presented results indicate further research is warranted into the engineered peptides as scaffolds for wound healing and tissue engineering.
Reliability Analysis of Data Storage Using Survival Signature and Logic Differential Calculus
- Patrik Rusnak
- Peter Sedlacek
- Stanisław Czapp
2023
The Data storage system is an important part of any information system. All the necessary data that must be available for the successful operation of the information system are stored here. Therefore, it is advisable to think about the reliability of such a data storage system. As part of reliability engineering, it is possible to perform a reliability analysis of any system. Therefore, the data storage system can be analyzed as well. As part of the reliability analysis, it is necessary to select the mathematical representation of the analyzed system. One such form is the structure function. A structure function is a mathematical representation of the analyzed system that maps the state of a system based on the state of its components. Main advantage is that the structure function can be used to describe a system of any complexity. However, if we have components of the same type in the system, the survival signature may be used as well. The structure function as well as the survival signature permits the use of multiple mathematical approaches such as logic differential calculus. Logic differential calculus can be used to detect situations where a change in the number of working components affects a change in the state of the system. This is useful in importance analysis, which is a part of the reliability analysis. In this paper, a reliability analysis will be performed for data storage in which multiple types of hard disk drives can be used as well as multiple methods of storing data on multiple disks using redundant array of independent disks.
Reliability estimation of underground horizontal fuel tank limit states
- Przemysław Sorn
- Mateusz Sondej
- Jarosław Górski
2023 Full text Bulletin of the Polish Academy of Sciences-Technical Sciences
Fuel tanks are designed with regard to standard loads and operating conditions. The investigations of the paper show the impact of such factors as tank corrosion and other means on the variation of stress fields and deformation of the underground horizontal tank shell. The introduction of probabilistic methods allows for structural reliability assessment. While the computational time of the entire tank FEM model is high, the preliminary analysis is restricted to the structural part only. The analysis makes it possible to optimize the structure with regard to construction costs
Reliable computationally-efficient behavioral modeling of microwave passives using deep learning surrogates in confined domains
- Sławomir Kozieł
- Nurullah Calik
- Peyman Mahouti
- Mehmet Belen
2023 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
The importance of surrogate modeling techniques has been steadily growing over the recent years in high-frequency electronics, including microwave engineering. Fast metamodels are employed to speedup design processes, especially those conducted at the level of full-wave electromagnetic (EM) simulations. The surrogates enable massive system evaluations at nearly EM accuracy and negligible costs, which is invaluable in parameter tuning, multi-objective optimization, or uncertainty quantification. Nevertheless, modeling of electrical characteristics of microwave components is impeded by nonlinearity of their electrical characteristics, the need for covering broad parameter ranges, as well as dimensionality issues. Recently, a two-stage modeling approach has been proposed, which addresses some of these issues by constraining the surrogate model domain to only include high-quality designs, thereby reducing the cardinality of the dataset required to establish an accurate metamodel. In this paper, a novel technique is proposed, which combines the two-stage modeling concept with Multi-head Deep Regression Network (MHDRN) surrogates customized to handle responses of microwave passives over wide ranges of operating frequencies and geometry parameters. Using three microstrip circuits, a superior performance of the proposed modeling framework is demonstrated with respect to multiple state-of-the-art benchmark methods. In particular, the relative RMS error is shown to reach the level of less than three percent for the datasets consisting of just a few hundred samples.
Remediation of soils on municipal rendering plant territories using Miscanthus × giganteus
- Anna Grzegórska
- Natalia Czaplicka
- Jacek Antonkiewicz
- Piotr Rybarczyk
- Agnieszka Baran
- Krzysztof Dobrzyński
- Dawid Zabrocki
- Andrzej Rogala
2023 Full text ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
Phytoremediation, as a cost-effective, highly efficient, environmentally friendly, and green approach, gained attention to the removal of metals, including heavy metals, from contaminated soils. The toxic nature of heavy metals can have an adverse effect on human health and the ecosystem, and their removal remains a worldwide problem. Therefore, in this study, a field experiment was carried out to evaluate the potential of Miscanthus × giganteus for the removal of ten microelements and heavy metals (Al, Zn, Fe, Pb, Cd, Co, Cr, Cu, Mn, Ni) from contaminated soil in the territory of a Municipal Waste Rendering Plant. Moreover, the effect of the incorporation of soil improver obtained upon composting biodegradable waste as well as the addition of highly contaminated post-industrial soil on the efficiency of phytoremediation and plant growth was described. The soil improver (SK-8) was applied to the soil at a rate of 200 Mg ha−1 and 400 Mg‧ha−1. Meanwhile, in the last object, 100 Mg‧ha−1 of highly contaminated post-industrial soil was added. Herein, the research was aimed at assessing the possibility of phytoextraction of heavy metals from soils with different physicochemical properties. The results showed that plants cultivated in soil with 400 Mg‧ha−1 of soil improver exhibited the highest yield (approximately 85% mass increase compared to the soil without additives). Furthermore, the application of a single dose of SK-8 (200 Mg ha−1) increased the uptake of Al, Fe, Co, Pb, Mn, Ni, and Cd by Miscanthus × giganteus compared to the soil without additives. Additionally, the performed biotests demonstrated no or low toxicity of the investigated soils affecting the test organisms. However, in all experiments, the phytorecovery of the elements did not exceed 1% of the amount introduced to the soil, which may result from a short cultivation period and large doses of SK-8 or highly contaminated post-industrial soil.
Removal of Arsenic from Wastewater Using Hydrochar Prepared from Red Macroalgae: Investigating Its Adsorption Efficiency and Mechanism
- Aisha Khanzada
- Muhammad Rizwan
- Hussein Al-Hazmi
- Joanna Majtacz
- Tonni Agustiono Kurniawan
- Jacek Makinia
2023 Full text Water
Arsenic (As) is a prominent carcinogen component produced via both geogenic and anthropogenic processes, posing serious risks to human health. This study aimed to investigate the potential of hydrochar prepared from red macroalgae for removing As from synthetic wastewater. The hydrochar was produced through 5 h hydrothermal carbonization (HTC) treatment at 200 °C, and then, chemically activated with ferric chloride hexahydrate (FeCl3·6H2O). SEM analysis revealed a permeable structure of hydrochar, while FTIR analysis detected the occurrence of several functional groups at the hydrochar interface. EDS analysis showed an increase in carbon concentration after FeCl3·6H2O activation. Hydrochar was then tested in batch experiments to investigate its As removal efficiency, with ICP-MS used to determine the levels of As after the adsorption process. The results showed that As removal efficiency increased with increasing initial As concentration from 50 to 250 mg/L, and the highest As removal efficiency was 84.75% at a pH of 6, initial concentration of 0.25 mg/L, and adsorbent dose of 1000 mg at 120 min. The Langmuir isotherm model supported the occurrence of homogeneous adsorption over the surface of hydrochar, while the pseudo-second-order model confirmed the chemisorptive nature of the process.
Removal of cyclohexane vapors from air in biotrickling filters: Effects of gas mixture composition and circular economy approach
- Piotr Rybarczyk
- Bartosz Szulczyński
- Dominik Dobrzyniewski
- Karolina Kucharska
- Jacek Gębicki
2023 Full text Chemical and Process Engineering : New Frontiers
This work presents results of investigations on biotrickling filtration of air polluted with cyclohexane co-treated in binary, ternary and quaternary volatile organic compounds (VOCs) mixtures, including vapors of hexane, toluene and ethanol. The removal of cyclohexane from a gas mixture depends on the physicochemical properties of the co-treated VOCs and the lower the hydrophobicity of the VOC, the higher the removal efficiency of cyclohexane. In this work, the performance of biotrickling filters treating VOCs mixtures is discussed based on surface tension of trickling liquid for the first time. A mixed natural – synthetic packing for biotrickling filters was utilized, showing promising performance and limited maintenance requirements. Maximum elimination capacity of about 95 g/(m 3·h) of cyclohexane was reached for the total VOCs inlet loading of about 450 g/(m 3·h). This work presents also a novel approach of combining biological air treatment with management of a spent trickling liquid in the perspective of circular economy assumptions. The waste liquid phase was applied to the plant cultivation, showing a potential for e.g. enhanced production of energetic biomass or polluted soil phytoremediation.
Renovation works in buildings in the area of former defensive fortifications
- Maciej Niedostatkiewicz
- Tomasz Majewski
- Adam Baryłka
2023 Full text Inżynieria Bezpieczeństwa Obiektów Antropogenicznych
he paperpresents the Complex of Buildings which was created in Gdańsk as a result of the reconstruction and development of the remains of the defensive fortifications of Redita Napoleońska. Some of the buildings of the Building Complex, after many years of operation, were in an emergency condition and required urgent renovation and repair work. The papercontains a detailed analysis of the technicalcondition of individual buildings of the Building Complex and analyzes the impact of the current use and the lack of regular periodic repairs on the technical efficiency of these facilities. Conceptual solutions in the field of renovation and repair workswere also presented, the purpose of which was to bring the objects in question to the proper technical condition.
Representativity of ISO test track surface based on controlled pass-by measurements
- Truls Berge
- Piotr Mioduszewski
2023
Within the Polish-Norwegian research project ELANORE, a limited Round Robin Test has been performed on four ISO tracks in Northern Europe. The basic objective of the project is to improve the EU directive on labelling of tyres for noise and rolling resistance. This directive is based on the measurement procedures proscribed in the UNECE Reg.117. Measurements on 3 ISO tracks were performed in 2021 and presented at InterNoise 2022. This paper adds results from tests conducted on a fourth ISO track as well as on trafficked roads with different conventional pavements: 2 in Norway (MA11 and SMA16) and 3 in Poland (SMA8, SMA11 and EACC). On all ISO test tracks and road test sites the same car, test tyres and test equipment as well as the same personnel were used to minimize the measurement uncertainties. Measurements were done using the controlled pass-by (CPB) method for vehicle test speeds between 40 and 90 km/h, with 2 test conditions: according to Reg.117 and with so-called "light test conditions". The main conclusion is that the noise ranking of the tyres on both, the ISO tracks and conventional pavements do not correspond to the ranking based on the label values given by tyre manufacturers.
Requirements for Residual Current Devices Intended for Electric Vehicle Charging Systems
- Stanisław Czapp
2023 Automatyka Elektryka Zakłócenia
The properties of residual current devices have been presented from the point of view of their ability to detect a specific shape of the residual current waveform. Moreover, the standard requirements relating to residual current protection used in electric vehicle charging installations have been pointed out. The operating characteristics of the IC-CPD and RDC-DD protections, which are intended for charging electric vehicles in mode 2 and mode 3, respectively, have been also discussed.
RESEARCH ON HYDRODYNAMIC PEEK JOURNAL BEARINGS LUBRICATED WITH WATER AND OIL
- Tomasz Żochowski
- Artur Olszewski
- Michał Wasilczuk
2023 Full text TRIBOLOGIA
The main purpose of the research was to determine the possibilities and experimentally test the benefits of replacing conventional oil lubrication with ecological water lubrication. Tests were carried out on a test rig for hydrodynamic radial bearings under conditions representative of the expected applications for the bearing in water turbines. Bearings made from the polymer material PEEK (polyether ether ketone) were tested under static loads. The tests were carried out for two types of lubrication: pure water and oil, with a viscosity of ISO VG 46. A comparison of friction coefficients and load-carrying capacity for both lubricants was made. During the tests, an interesting phenomenon of polymer material running in was observed for relatively high pressures when lubricated with a very low-viscosity lubricating medium, i.e., water (pressures in the bearing over 2 MPa).